Outcome quality and long-term (≥15 years) stability after Class II:2 Herbst-multibracket appliance treatment in comparison to untreated Class I controls

Outcome quality and long-term (≥15 years) stability after Class II:2 Herbst-multibracket... Summary Aim To investigate the outcome quality and the long-term (≥15 years) post-treatment (Tx) changes after Class II:2 Herbst-multibracket appliance (MBA) Tx. Subjects and Methods In this longitudinal observational study, a recall of Class II:2 patients who had been treated by a Herbst-MBA during adolescence was conducted. Study models from before and after active Tx, after retention and after recall were assessed using standard occlusal variables and the peer assessment rating index (PAR). These data were compared to historical untreated Class I controls. Results Twenty out of 33 patients (61%) could be located and participated at age 33.9 ± 2.7 years. When comparing their data to the 13 patients who did not participate, the pre- and post-Tx occlusal findings did not differ systematically; however, the PAR scores of the non-participants were by 3.3–8.2 points higher at all times and the non-participants were 2.1–2.5 years older. Pre-Tx at age 14.4 ± 2.7 years, the participants showed the following mean values: PAR = 15.0 ± 7.0, Class II molar relationship (MR) = 0.8 ± 0.3 cusp widths (cw), overbite = 5.3 ± 1.3 mm. After Tx, a PAR score of 2.9 ± 1.3 and a super Class I MR (−0.1 ± 0.1 cw) with normal overbite (1.2 ± 0.8 mm) existed. At recall, a PAR score increase to 5.9 ± 3.6 points had occurred, mainly caused by an increase of overbite to 2.5 ± 1.5 mm. The average MR remained Class I (0.0 ± 0.2 cw). For all variables, the untreated controls exhibited similar findings. Conclusion The occlusal outcome of Class II:2 Herbst-MBA Tx exhibited very good long-term stability. While mild post-Tx changes occurred, the long-term findings are similar to untreated Class I controls. Introduction Class II:2 malocclusions are said to be difficult to treat and to have a high risk for relapse (1, 2). For children in European populations, prevalences of up to 10% have been reported for this malocclusion (3, 4). Although a systematic review concluded that only highly biased evidence existed with regard to the effectiveness of Class II:2 therapy and the stability of the respective treatment (Tx) results (5), several retrospective investigations have shown Herbst-multibracket appliance (MBA) Tx to be most effective in terms of Class II:2 correction (6–9). Furthermore, the occlusal correction achieved by Herbst-MBA Tx was found to be relatively stable 2 years post-treatment (10). However, to date no evidence is available in terms of long-term stability (11), which is also true for most other Tx approaches used for Class II:2 correction. The only existing long-term data (≥15 years) deal with a sample of 18 patients after early Tx with activators (12) on the one hand, and a sample of 62 patients after fixed appliance Tx on the other hand (13). Additional publications (n = 66 and n = 44) report data from 5 years out of retention after fixed appliance Tx (14, 15). The degree of stability reported in these papers ranges between remarkably and moderately stable and shows large variability. No comparison to an untreated sample was made in any of the above mentioned papers Due to the specific aetiology and controversial stability reputation of Class II:2 malocclusions, it seems to be of particular interest to determine additional data and eventually reveal a Tx approach enabling successful and long-term stable correction of this type of malocclusion. Therefore, the aim of the present investigation was to assess the outcome quality and the long-term (≥15 years) post-Tx changes after Class II:2 Herbst-MBA Tx compared to untreated controls. Subjects and methods After obtaining ethical approval (Nr. 146/13) and study registration (WHO: ID DRKS00006354), the archive of the Department of Orthodontics at the University of Giessen, Germany was searched for all Class II:2 patients (irrespective of Tx outcome) who had been treated with a Herbst-MBA and whose active Tx was finished at least 15 years ago. A total of 33 patients with a mean age of 14.4 years at the start of Tx were determined. All these patients had a Class II occlusal relationship (mean: 0.8 cusp widths) with the mandibular dentition being positioned posteriorly compared to the ‘normal’ Class I relationship. In addition, at least two maxillary incisors were retroclined and exhibited an anterior deep overbite (mean: 5.3 mm). Tx was carried out using a Herbst appliance Type I (Dentaurum®) as well as different types of labial straight-wire MBAs. In 14 of the 20 patients, the Tx protocol had started with 8.6 ± 5.6 months of fixed appliance Tx for upper incisor proclination to enable Herbst appliance insertion and adjustment in an incisal edge-to-edge relationship. In the remaining six patients, Tx could be started directly with the insertion of the Herbst appliance. The Herbst appliance was removed after 7.7 ± 1.7 months and replaced by a full arch MBA in both jaws in order to obtain proper occlusal settling and finishing. The total Tx duration amounted to 24.9 ± 6.9 months. All patients were treated non-extraction. Patient location and contact was attempted using the information in the patients’ records as well as the internet (search engines, online phone directories) as sources. While 27 of the potential 33 patients could be located and were asked to participate in the current investigation, 20 finally agreed and took part at age 33.9 ± 2.7 years. An informed consent was acquired from all participants before starting the examination. Impressions of the upper and lower arch as well as a wax bite were taken of all participants. In addition, study models in centric occlusion from before and after Tx as well as after retention were assessed and compared to the current findings in order to evaluate the changes that had occurred since the end of active Tx. The sagittal molar and canine relationships (right, left) as well as the overjet and the overbite were assessed for all occasions (T0: before Tx, T1: after Tx, T2: after retention, T3: recall). Visual ratings of the molar relationship were performed to the nearest 0.25 cusp widths (cw) and classified as Classes I, II, or III, while a manual calliper was used to accomplish linear measurements to the nearest 0.5 mm. In addition, the peer assessment rating index (PAR) (16) was utilised. A PAR-certified operator (N.B.) performed the respective ratings according to the respective guidelines (16) using an original PAR ruler. At recall (T3), no retainers at all were worn by 11 of the 20 participants; 4 of them had already been without retention at T2. Of the remaining nine participants, eight wore a lower bonded canine-to-canine retainer (seven bonded on the canines only, one bonded on all six teeth) while one participant had an upper bonded retainer only. Control group A ‘double negative, normal’ historical control group was used for comparison of the post-Tx changes. It was generated from a longitudinal study on growth changes in the dental arches in Finland which had followed the patients from age 7 years (17). The records obtained at age 12/13 years (T0), age 15 years (T1), and age 33 years (T3) were considered to correspond best to the current Herbst-MBA sample regarding age (Table 2). From all original Class I participants (17) with no orthodontic Tx need (n = 33), those who still exhibited a bilateral Class I relationship at the age of 15 years (which is more or less in concordance with the treated Class II:2 sample; Table 2) formed the untreated control group (n = 31) for the current investigation. Study models from both relevant time points T1 (age 15.4 ± 0.4 years) and T3 (age 32.9 ± 1.2 years) were available from all these untreated subjects (n = 31). Table 2. Comparison of the Class II:2 and the controls: the mean value (Mean), standard deviation (SD), and P value (P) of the respective group difference are given for age and the duration of the observation periods. Class II:2 Controls P (12♀:8♂) (17♀:14♂) Mean ± SD Mean ± SD Age T0 years 13.5 ± 1.95 13.0 ± 0.42 0.549 T1 15.7 ± 1.88 15.4 ± 0.36 0.787 T2 17.6 ± 2.24 — — T3 33.9 ± 2.67 32.9 ± 1.22 0.089 Observation period T1–T0 months 24.9 ± 6.91 29.3 ± 3.61 0.004 (Treatment) T2–T1 25.9 ± 10.81 — — (Retention) T3–T1 years 18.3 ± 2.44 17.5 ± 1.19 0.475 (Long-term) Class II:2 Controls P (12♀:8♂) (17♀:14♂) Mean ± SD Mean ± SD Age T0 years 13.5 ± 1.95 13.0 ± 0.42 0.549 T1 15.7 ± 1.88 15.4 ± 0.36 0.787 T2 17.6 ± 2.24 — — T3 33.9 ± 2.67 32.9 ± 1.22 0.089 Observation period T1–T0 months 24.9 ± 6.91 29.3 ± 3.61 0.004 (Treatment) T2–T1 25.9 ± 10.81 — — (Retention) T3–T1 years 18.3 ± 2.44 17.5 ± 1.19 0.475 (Long-term) —, data not available. View Large Table 2. Comparison of the Class II:2 and the controls: the mean value (Mean), standard deviation (SD), and P value (P) of the respective group difference are given for age and the duration of the observation periods. Class II:2 Controls P (12♀:8♂) (17♀:14♂) Mean ± SD Mean ± SD Age T0 years 13.5 ± 1.95 13.0 ± 0.42 0.549 T1 15.7 ± 1.88 15.4 ± 0.36 0.787 T2 17.6 ± 2.24 — — T3 33.9 ± 2.67 32.9 ± 1.22 0.089 Observation period T1–T0 months 24.9 ± 6.91 29.3 ± 3.61 0.004 (Treatment) T2–T1 25.9 ± 10.81 — — (Retention) T3–T1 years 18.3 ± 2.44 17.5 ± 1.19 0.475 (Long-term) Class II:2 Controls P (12♀:8♂) (17♀:14♂) Mean ± SD Mean ± SD Age T0 years 13.5 ± 1.95 13.0 ± 0.42 0.549 T1 15.7 ± 1.88 15.4 ± 0.36 0.787 T2 17.6 ± 2.24 — — T3 33.9 ± 2.67 32.9 ± 1.22 0.089 Observation period T1–T0 months 24.9 ± 6.91 29.3 ± 3.61 0.004 (Treatment) T2–T1 25.9 ± 10.81 — — (Retention) T3–T1 years 18.3 ± 2.44 17.5 ± 1.19 0.475 (Long-term) —, data not available. View Large Statistics In order to minimize the error of the method, all measurements and ratings were performed twice (N.B.) with a time interval of 2–4 weeks in between, and the mean value of both was utilised for further calculations. A non-normal distribution according to Shapiro–Wilk and Kolmogorov–Smirnov tests was seen for the majority of the data. Nevertheless, for the sake of comparison with other published data, the mean value and standard deviation are used throughout the text of the manuscript. However, in order to allow detailed interpretation, the median, minimum and maximum values are given in all respective tables. After performing a descriptive statistical analysis, the Mann–Whitney U test was applied for most group comparisons due to the non-normal distribution of the data. When comparing more than two groups, the Kruskal–Wallis test was used. Although the study followed an explorative design, a variety of inferential methods have been used to fully utilize the information in the data. The number of conducted tests adds up to a multiple testing situation (which leads to an accumulation of false positive results); being aware of this limitation, it was decided to regard P-values of up to 0.15 as hints of possible effects. This procedure was chosen as explorative data analysis does not use a fixed threshold value of probability to search for ‘patterns’ or ‘structure’ in experimental data although robust inferential statistical procedures are utilised (18). The 0.1–0.15 threshold was heuristically adapted from a selection process commonly used to screen for relevant factors in logistic regression and similar analytical procedures. Based on the properties of the measured parameters, the Intraclass Correlation Coefficient (ICC) was chosen to assess observer reliability for most variables. The ICC allows for examination of reliability of repeated measurements based on the exact agreement of the measurements. In contrast, for the ratings of all PAR index components, the consistency of measurements was assessed (Kendall’s Tau-b). While the ICC values were rather high for all measurements (mean: 0.9; standard deviation: 0.1; median: 0.9), the consistency values were slightly lower for the PAR components (mean: 0.7; standard deviation: 0.2; median: 0.7). Results Participants versus non-participants (Table 1, Figure 1, Supplementary Tables 1 and 2) As 20 of the 33 potential patients agreed to participate, the participation rate was 61% (with respect to the number of locatable patients). Nevertheless, 13 patients were not available for participation due to lack of interest or other reasons (Figure 1). Table 1. Comparison of the Class II:2 participants’ and non-participants’ data: the mean value (mean), standard deviation (SD) and P-value (P) of the respective group difference are given for age, duration of the observation periods, overbite, sagittal molar relationship, and PAR score. Participants Non-participants P (12♀:8♂) (5♀:8♂) Mean ± SD Mean ± SD Age T0 Years 13.5 ± 1.95 15.8 ± 3.04 0.013 T1 15.7 ± 1.88 17.8 ± 3.42 0.031 T2 17.6 ± 2.24 20.1 ± 4.04 0.057 Observation periods T1–T0 Months 24.9 ± 6.91 24.0 ± 7.95 0.738 (Treatment) T2–T1 25.9 ± 10.81 28.5 ± 12.01 0.184 (Retention) Molar relationship T0 cw 0.8 ± 0.31 0.8 ± 0.16 0.784 T1 −0.1 ± 0.12 0.0 ± 0.13 0.332 T2 0.0 ± 0.13 0.0 ± 0.15 0.187 Overbite T0 mm 5.3 ± 1.32 5.7 ± 2.14 0.519 T1 1.2 ± 0.77 1.4 ± 0.59 0.319 T2 2.3 ± 1.21 2.7 ± 1.06 0.309 PAR T0 Total score 15.0 ± 6.95 23.2 ± 7.29 0.019 T1 2.9 ± 1.33 6.2 ± 2.79 0.002 T2 3.1 ± 2.00 6.6 ± 2.53 0.001 Participants Non-participants P (12♀:8♂) (5♀:8♂) Mean ± SD Mean ± SD Age T0 Years 13.5 ± 1.95 15.8 ± 3.04 0.013 T1 15.7 ± 1.88 17.8 ± 3.42 0.031 T2 17.6 ± 2.24 20.1 ± 4.04 0.057 Observation periods T1–T0 Months 24.9 ± 6.91 24.0 ± 7.95 0.738 (Treatment) T2–T1 25.9 ± 10.81 28.5 ± 12.01 0.184 (Retention) Molar relationship T0 cw 0.8 ± 0.31 0.8 ± 0.16 0.784 T1 −0.1 ± 0.12 0.0 ± 0.13 0.332 T2 0.0 ± 0.13 0.0 ± 0.15 0.187 Overbite T0 mm 5.3 ± 1.32 5.7 ± 2.14 0.519 T1 1.2 ± 0.77 1.4 ± 0.59 0.319 T2 2.3 ± 1.21 2.7 ± 1.06 0.309 PAR T0 Total score 15.0 ± 6.95 23.2 ± 7.29 0.019 T1 2.9 ± 1.33 6.2 ± 2.79 0.002 T2 3.1 ± 2.00 6.6 ± 2.53 0.001 cw, cusp widths. View Large Table 1. Comparison of the Class II:2 participants’ and non-participants’ data: the mean value (mean), standard deviation (SD) and P-value (P) of the respective group difference are given for age, duration of the observation periods, overbite, sagittal molar relationship, and PAR score. Participants Non-participants P (12♀:8♂) (5♀:8♂) Mean ± SD Mean ± SD Age T0 Years 13.5 ± 1.95 15.8 ± 3.04 0.013 T1 15.7 ± 1.88 17.8 ± 3.42 0.031 T2 17.6 ± 2.24 20.1 ± 4.04 0.057 Observation periods T1–T0 Months 24.9 ± 6.91 24.0 ± 7.95 0.738 (Treatment) T2–T1 25.9 ± 10.81 28.5 ± 12.01 0.184 (Retention) Molar relationship T0 cw 0.8 ± 0.31 0.8 ± 0.16 0.784 T1 −0.1 ± 0.12 0.0 ± 0.13 0.332 T2 0.0 ± 0.13 0.0 ± 0.15 0.187 Overbite T0 mm 5.3 ± 1.32 5.7 ± 2.14 0.519 T1 1.2 ± 0.77 1.4 ± 0.59 0.319 T2 2.3 ± 1.21 2.7 ± 1.06 0.309 PAR T0 Total score 15.0 ± 6.95 23.2 ± 7.29 0.019 T1 2.9 ± 1.33 6.2 ± 2.79 0.002 T2 3.1 ± 2.00 6.6 ± 2.53 0.001 Participants Non-participants P (12♀:8♂) (5♀:8♂) Mean ± SD Mean ± SD Age T0 Years 13.5 ± 1.95 15.8 ± 3.04 0.013 T1 15.7 ± 1.88 17.8 ± 3.42 0.031 T2 17.6 ± 2.24 20.1 ± 4.04 0.057 Observation periods T1–T0 Months 24.9 ± 6.91 24.0 ± 7.95 0.738 (Treatment) T2–T1 25.9 ± 10.81 28.5 ± 12.01 0.184 (Retention) Molar relationship T0 cw 0.8 ± 0.31 0.8 ± 0.16 0.784 T1 −0.1 ± 0.12 0.0 ± 0.13 0.332 T2 0.0 ± 0.13 0.0 ± 0.15 0.187 Overbite T0 mm 5.3 ± 1.32 5.7 ± 2.14 0.519 T1 1.2 ± 0.77 1.4 ± 0.59 0.319 T2 2.3 ± 1.21 2.7 ± 1.06 0.309 PAR T0 Total score 15.0 ± 6.95 23.2 ± 7.29 0.019 T1 2.9 ± 1.33 6.2 ± 2.79 0.002 T2 3.1 ± 2.00 6.6 ± 2.53 0.001 cw, cusp widths. View Large Figure 1. View largeDownload slide Flow chart of the study participants/non-participants of the Class II:2 sample. The numbers of total Herbst-MBA patients (active Tx completed by January, 1st 2015) as well as potential participants and the results of the recruitment process are given. Figure 1. View largeDownload slide Flow chart of the study participants/non-participants of the Class II:2 sample. The numbers of total Herbst-MBA patients (active Tx completed by January, 1st 2015) as well as potential participants and the results of the recruitment process are given. Without any known reason, the 20 participants and the 13 non-participants of the Class II:2 sample differed by about 2 years in terms of age before Tx, after Tx, and after retention (P = 0.013–0.057). However, the duration of both the treatment (T1–T0) and retention periods was similar (P = 0.184–0.738). Although the classical Class II:2 malocclusion characteristics (Class II molar relationship, overbite) did not differ systematically at any time the mean PAR score values were by 3.3–8.2 points lower in the participants at all three examination time points (P = 0.001–0.019). Participants versus controls (Table 2) The only notable difference between the Class II:2 participants and the controls was the length of the observation period (T1–T0), which was by 5 months longer in the controls (24.9 versus 29.3 months, P = 0.004). Tx and long-term post-Tx changes (Table 3, Supplementary Tables 1–5, Figure 2, Supplementary Figure 1) As anticipated, at T0 marked differences existed between the Class II:2 participants and the untreated Class I controls for molar and canine relationships as well as for overbite and PAR score (Table 3, Supplementary Table 4, Figure 2). Table 3. Sagittal molar and canine relationships (mean left/right) as well as overbite, overjet, and the total PAR score in the Class II:2 and the controls at T0, T1, and T3. T0 T1 T3 Mean SD Min Max Med P Mean SD Min Max Med P Mean SD Min Max Med P Molar relationship cw Class II:2 0.8 0.31 0.3 1.3 0.8 0.000 −0.1 0.12 −0.3 0.2 −0.1 0.891 0.0 0.15 −0.3 0.4 0.0 0.101 Controls 0.0 0.16 −0.3 0.4 0.0 −0.1 0.15 −0.3 0.3 −0.1 −0.1 0.12 −0.3 0.3 −0.1 Canine relationship cw Class II:2 0.6 0.14 0.4 0.8 0.7 0.000 0.2 0.09 0.0 0.3 0.2 0.188 0.2 0.12 −0.1 0.3 0.2 0.875 Controls 0.3 0.12 0.0 0.5 0.3 0.2 0.10 0.0 0.5 0.3 0.2 0.12 0.0 0.4 0.1 Overbite mm Class II:2 5.3 1.32 3.5 9.0 5.0 0.000 1.2 0.77 0.3 2.5 1.0 0.000 2.5 1.49 0.0 5.3 2.1 0.885 Controls 2.7 0.88 1.3 4.0 2.8 2.7 0.96 1.0 4.8 2.5 2.4 1.21 0.5 4.5 2.3 Overjet mm Class II:2 4.1 1.70 1.8 7.0 3.8 0.422 1.8 0.61 0.5 2.8 1.8 0.000 2.2 0.85 0.0 3.8 2.3 0.001 Controls 3.6 0.83 1.5 4.8 3.5 3.2 0.74 1.5 4.8 3.3 3.2 0.81 1.8 4.8 3.3 Total PAR score Class II:2 15.0 6.95 6.0 27.5 15.0 0.019 2.9 1.33 1.5 5.5 2.5 0.000 5.9 3.62 2.0 16.5 5.5 0.002 Controls 10.5 4.24 3.5 17.0 10.5 8.8 3.71 2.5 15.0 8.5 8.9 3.34 2.5 18.0 9.0 T0 T1 T3 Mean SD Min Max Med P Mean SD Min Max Med P Mean SD Min Max Med P Molar relationship cw Class II:2 0.8 0.31 0.3 1.3 0.8 0.000 −0.1 0.12 −0.3 0.2 −0.1 0.891 0.0 0.15 −0.3 0.4 0.0 0.101 Controls 0.0 0.16 −0.3 0.4 0.0 −0.1 0.15 −0.3 0.3 −0.1 −0.1 0.12 −0.3 0.3 −0.1 Canine relationship cw Class II:2 0.6 0.14 0.4 0.8 0.7 0.000 0.2 0.09 0.0 0.3 0.2 0.188 0.2 0.12 −0.1 0.3 0.2 0.875 Controls 0.3 0.12 0.0 0.5 0.3 0.2 0.10 0.0 0.5 0.3 0.2 0.12 0.0 0.4 0.1 Overbite mm Class II:2 5.3 1.32 3.5 9.0 5.0 0.000 1.2 0.77 0.3 2.5 1.0 0.000 2.5 1.49 0.0 5.3 2.1 0.885 Controls 2.7 0.88 1.3 4.0 2.8 2.7 0.96 1.0 4.8 2.5 2.4 1.21 0.5 4.5 2.3 Overjet mm Class II:2 4.1 1.70 1.8 7.0 3.8 0.422 1.8 0.61 0.5 2.8 1.8 0.000 2.2 0.85 0.0 3.8 2.3 0.001 Controls 3.6 0.83 1.5 4.8 3.5 3.2 0.74 1.5 4.8 3.3 3.2 0.81 1.8 4.8 3.3 Total PAR score Class II:2 15.0 6.95 6.0 27.5 15.0 0.019 2.9 1.33 1.5 5.5 2.5 0.000 5.9 3.62 2.0 16.5 5.5 0.002 Controls 10.5 4.24 3.5 17.0 10.5 8.8 3.71 2.5 15.0 8.5 8.9 3.34 2.5 18.0 9.0 For each variable, the mean value (Mean), standard deviation (SD), minimum (Min), maximum (Max), and median value (Med) as well as the P value (P) of the respective group difference are given. cw, cusp widths. View Large Table 3. Sagittal molar and canine relationships (mean left/right) as well as overbite, overjet, and the total PAR score in the Class II:2 and the controls at T0, T1, and T3. T0 T1 T3 Mean SD Min Max Med P Mean SD Min Max Med P Mean SD Min Max Med P Molar relationship cw Class II:2 0.8 0.31 0.3 1.3 0.8 0.000 −0.1 0.12 −0.3 0.2 −0.1 0.891 0.0 0.15 −0.3 0.4 0.0 0.101 Controls 0.0 0.16 −0.3 0.4 0.0 −0.1 0.15 −0.3 0.3 −0.1 −0.1 0.12 −0.3 0.3 −0.1 Canine relationship cw Class II:2 0.6 0.14 0.4 0.8 0.7 0.000 0.2 0.09 0.0 0.3 0.2 0.188 0.2 0.12 −0.1 0.3 0.2 0.875 Controls 0.3 0.12 0.0 0.5 0.3 0.2 0.10 0.0 0.5 0.3 0.2 0.12 0.0 0.4 0.1 Overbite mm Class II:2 5.3 1.32 3.5 9.0 5.0 0.000 1.2 0.77 0.3 2.5 1.0 0.000 2.5 1.49 0.0 5.3 2.1 0.885 Controls 2.7 0.88 1.3 4.0 2.8 2.7 0.96 1.0 4.8 2.5 2.4 1.21 0.5 4.5 2.3 Overjet mm Class II:2 4.1 1.70 1.8 7.0 3.8 0.422 1.8 0.61 0.5 2.8 1.8 0.000 2.2 0.85 0.0 3.8 2.3 0.001 Controls 3.6 0.83 1.5 4.8 3.5 3.2 0.74 1.5 4.8 3.3 3.2 0.81 1.8 4.8 3.3 Total PAR score Class II:2 15.0 6.95 6.0 27.5 15.0 0.019 2.9 1.33 1.5 5.5 2.5 0.000 5.9 3.62 2.0 16.5 5.5 0.002 Controls 10.5 4.24 3.5 17.0 10.5 8.8 3.71 2.5 15.0 8.5 8.9 3.34 2.5 18.0 9.0 T0 T1 T3 Mean SD Min Max Med P Mean SD Min Max Med P Mean SD Min Max Med P Molar relationship cw Class II:2 0.8 0.31 0.3 1.3 0.8 0.000 −0.1 0.12 −0.3 0.2 −0.1 0.891 0.0 0.15 −0.3 0.4 0.0 0.101 Controls 0.0 0.16 −0.3 0.4 0.0 −0.1 0.15 −0.3 0.3 −0.1 −0.1 0.12 −0.3 0.3 −0.1 Canine relationship cw Class II:2 0.6 0.14 0.4 0.8 0.7 0.000 0.2 0.09 0.0 0.3 0.2 0.188 0.2 0.12 −0.1 0.3 0.2 0.875 Controls 0.3 0.12 0.0 0.5 0.3 0.2 0.10 0.0 0.5 0.3 0.2 0.12 0.0 0.4 0.1 Overbite mm Class II:2 5.3 1.32 3.5 9.0 5.0 0.000 1.2 0.77 0.3 2.5 1.0 0.000 2.5 1.49 0.0 5.3 2.1 0.885 Controls 2.7 0.88 1.3 4.0 2.8 2.7 0.96 1.0 4.8 2.5 2.4 1.21 0.5 4.5 2.3 Overjet mm Class II:2 4.1 1.70 1.8 7.0 3.8 0.422 1.8 0.61 0.5 2.8 1.8 0.000 2.2 0.85 0.0 3.8 2.3 0.001 Controls 3.6 0.83 1.5 4.8 3.5 3.2 0.74 1.5 4.8 3.3 3.2 0.81 1.8 4.8 3.3 Total PAR score Class II:2 15.0 6.95 6.0 27.5 15.0 0.019 2.9 1.33 1.5 5.5 2.5 0.000 5.9 3.62 2.0 16.5 5.5 0.002 Controls 10.5 4.24 3.5 17.0 10.5 8.8 3.71 2.5 15.0 8.5 8.9 3.34 2.5 18.0 9.0 For each variable, the mean value (Mean), standard deviation (SD), minimum (Min), maximum (Max), and median value (Med) as well as the P value (P) of the respective group difference are given. cw, cusp widths. View Large Figure 2. View largeDownload slide Development of molar relationship, overbite, overjet, and total PAR score from T0 until T3 in the treated Class II:2 (Tx) and the controls. While the dotted lines suggest certain changes, it is unknown what exactly happened between the respective time points. Figure 2. View largeDownload slide Development of molar relationship, overbite, overjet, and total PAR score from T0 until T3 in the treated Class II:2 (Tx) and the controls. While the dotted lines suggest certain changes, it is unknown what exactly happened between the respective time points. The detailed values for overjet, overbite as well as molar and canine relationships at T0, T1, and T3 are given in Table 3 (T2 in Supplementary Table 1). The respective changes during the observation periods T1–T0 and T3–T1 are shown in Supplementary Table 3 as well as Figure 2. After Tx, the mean molar relationship was −0.1 cw at T1 and 0.0 cw at T3 in the Class II:2, while it was −0.1 cw (T1 and T3) in the controls (P = 0.101–0.891). The canine relationship showed a mean value of 0.2 cw at both occasions and in both groups (P = 0.188–0.875). The mean overbite was by 1.5 mm smaller in the Class II:2 sample than in the controls (P = 0.000) after Tx, while it was almost identical after the long-term observation (2.5 versus 2.4 mm; P = 0.885). For overjet, the values were by 1.0–1.4 mm smaller in the Class II:2 sample at both occasions (P = 0.000–0.001). The detailed scores for the PAR index (total score as well as contributing components) at T0, T1, and T3 are given in Supplementary Table 4 (T2 in Supplementary Table 2). The respective changes during the observation periods T1–T0 and T3–T1 are shown in Supplementary Table 5. Immediately after Tx (T1), the mean total PAR score was distinctly lower by 5.9 points (P = 0.000) in the Class II:2 when compared with the controls (Table 3). At T3 a difference of 3.0 points (P = 0.002) prevailed, which was mainly due to the differences for the maxillary and mandibular anterior segments exhibiting lower values (=better alignment) in the Class II:2 than in the controls: 0.8 versus 2.0 and 1.1 versus 2.5 points (P = 0.000; Supplementary Table 4). Looking at the percentage of patients exhibiting ‘perfect’ PAR component scores (=0), it is most stunning to see that a perfect score for ‘occlusion’ is completely absent in both groups at all occasions (Supplementary Figure 1). Generally, the lowest percentages existed at T0 (both groups), while at T1 most components in the Class II:2 exhibited a major improvement. After long-term observation (T3), the Class II:2 group presented a perfect overbite slightly less frequent than the controls (45% versus 61%) while similar prevalences were only seen for perfect centrelines (95% versus 90%). Notably more perfect scores were found in the Class II:2 participants when compared with the controls for overjet (95%/71%) and maxillary/mandibular anterior segments (45%/45% versus 6%/3%). Influence of bonded retainers (Table 4) As 8 of the 20 participants still wore a lower canine-to-canine retainer at T3, a separate comparison of these two subgroups and the controls was performed for the long-term changes (T3–T1) of the total PAR score as well as the components ‘ mandibular anterior’, overjet and overbite. A distinct group difference (P = 0.002) was seen for the total PAR score. The retainer group exhibited an increase by 1.6 ± 2.0 points, while the group without retainers showed an increase by 4.0 ± 3.5 points; in the controls, the total PAR score increased by 0.1 ± 2.9 points. Similar, but less pronounced differences (P = 0.009–0.313) were seen for the components “mandibular anterior” and overbite (Table 4). Table 4. Changes of the total PAR score as well as the (weighted) components mandibular anterior, overjet, and overbite during long-term observation (T3–T1) in the Class II:2 with no retainer in the lower jaw at T3 (n = 12), the Class II:2 wearing a bonded lower canine-to-canine retainer at T3 (n = 8) and the controls. Class II:2 Controls (n = 31) P No retainer at T3 (n = 12) Bonded lower retainer at T3 (n = 8) Mean SD Min Max Med Mean SD Min Max Med Mean SD Min Max Med Total PAR score changes 4.0 3.55 0.0 12.0 3.3 1.6 1.99 −0.5 5.0 1.3 0.1 3.09 −5.5 8.0 −0.5 0.002 PAR component changes Mandibular anterior 1.4 1.24 0.0 3.5 1.0 0.0 0.00 0.0 0.0 0.0 0.9 1.17 −1.0 3.5 0.5 0.009 Overjet 0.3 1.54 −3.0 3.0 0.0 0.4 1.06 0.0 3.0 0.0 −0.3 2.49 −6.0 6.0 0.0 0.662 Overbite 1.3 1.30 0.0 4.0 2.0 0.8 0.89 0.0 2.0 0.5 −0.1 1.29 −2.0 1.0 0.0 0.313 Class II:2 Controls (n = 31) P No retainer at T3 (n = 12) Bonded lower retainer at T3 (n = 8) Mean SD Min Max Med Mean SD Min Max Med Mean SD Min Max Med Total PAR score changes 4.0 3.55 0.0 12.0 3.3 1.6 1.99 −0.5 5.0 1.3 0.1 3.09 −5.5 8.0 −0.5 0.002 PAR component changes Mandibular anterior 1.4 1.24 0.0 3.5 1.0 0.0 0.00 0.0 0.0 0.0 0.9 1.17 −1.0 3.5 0.5 0.009 Overjet 0.3 1.54 −3.0 3.0 0.0 0.4 1.06 0.0 3.0 0.0 −0.3 2.49 −6.0 6.0 0.0 0.662 Overbite 1.3 1.30 0.0 4.0 2.0 0.8 0.89 0.0 2.0 0.5 −0.1 1.29 −2.0 1.0 0.0 0.313 View Large Table 4. Changes of the total PAR score as well as the (weighted) components mandibular anterior, overjet, and overbite during long-term observation (T3–T1) in the Class II:2 with no retainer in the lower jaw at T3 (n = 12), the Class II:2 wearing a bonded lower canine-to-canine retainer at T3 (n = 8) and the controls. Class II:2 Controls (n = 31) P No retainer at T3 (n = 12) Bonded lower retainer at T3 (n = 8) Mean SD Min Max Med Mean SD Min Max Med Mean SD Min Max Med Total PAR score changes 4.0 3.55 0.0 12.0 3.3 1.6 1.99 −0.5 5.0 1.3 0.1 3.09 −5.5 8.0 −0.5 0.002 PAR component changes Mandibular anterior 1.4 1.24 0.0 3.5 1.0 0.0 0.00 0.0 0.0 0.0 0.9 1.17 −1.0 3.5 0.5 0.009 Overjet 0.3 1.54 −3.0 3.0 0.0 0.4 1.06 0.0 3.0 0.0 −0.3 2.49 −6.0 6.0 0.0 0.662 Overbite 1.3 1.30 0.0 4.0 2.0 0.8 0.89 0.0 2.0 0.5 −0.1 1.29 −2.0 1.0 0.0 0.313 Class II:2 Controls (n = 31) P No retainer at T3 (n = 12) Bonded lower retainer at T3 (n = 8) Mean SD Min Max Med Mean SD Min Max Med Mean SD Min Max Med Total PAR score changes 4.0 3.55 0.0 12.0 3.3 1.6 1.99 −0.5 5.0 1.3 0.1 3.09 −5.5 8.0 −0.5 0.002 PAR component changes Mandibular anterior 1.4 1.24 0.0 3.5 1.0 0.0 0.00 0.0 0.0 0.0 0.9 1.17 −1.0 3.5 0.5 0.009 Overjet 0.3 1.54 −3.0 3.0 0.0 0.4 1.06 0.0 3.0 0.0 −0.3 2.49 −6.0 6.0 0.0 0.662 Overbite 1.3 1.30 0.0 4.0 2.0 0.8 0.89 0.0 2.0 0.5 −0.1 1.29 −2.0 1.0 0.0 0.313 View Large Discussion The present investigation is the first to evaluate the outcome quality and the long-term post-Tx changes after Class II:2 Tx in comparison to untreated controls. As the mechanism of Class II:2 correction using a Herbst-MBA as well as the nature (dental/skeletal) of relapse are well known and have been published before (6, 8, 9), an analysis of the effects emerging during each the Herbst and the subsequent MBA phase separately was considered unnecessary for the current investigation. Therefore, it was predetermined to concentrate on the post-Tx effects and the occlusal stability. Subjects: participants versus non-participants A recall of all eligible Class II:2 patients who had received active Tx at the study centre during the period 1986–2000 was performed. Despite this long-term period, a standardized Tx approach had been pursued in all these patients, even if several practitioners conditionally under supervision of two senior orthodontists were involved. Only one investigator undertook all investigation-relevant study model assessments. In contrast to the treated Class II:2 participants, the non-participants were on average 2.1–2.5 years older (P < 0.06) and exhibited by 3.3–8.2 points higher PAR scores (P < 0.02) at T0, T1, and T2. While this difference probably influences the external validity of the present results, uniform data was seen for Tx duration (T1–T0), length of the retention period (T2–T1), molar relationship, and overbite (T0, T1, T2). Therefore, it can be hypothesized that no relevant selection bias prevailed. Subjects: untreated controls The untreated Class I control group was quite uniform in terms of age at both T0 (13.0 ± 0.4 years) and T1 (15.4 ± 0.4 years), as the sample comprised of participants of a longitudinal study on growth changes in the dental arches (17). No orthodontic Tx need existed when they were enrolled in this original study at age 7 years; however, at age 15 years (T1 in the present investigation) some participants had developed minor crowding. After long-term observation, the variation in age had slightly increased until T3 (32.9 ± 1.2 years). Nevertheless, the total PAR score had been quite stable during the whole observation period (T0: 10.5 ± 4.2; T1: 8.8 ± 3.7; T3: 8.9 ± 3.3) The decrease during T1–T0 was mainly a result of overjet reduction (Supplementary Tables 3 and 5), which can be attributed to natural mandibular growth changes during this period (age 13–15) which includes the peak of the pubertal growth spurt. Validity of the control group Using an untreated Class I sample as control for treated Class II:2 patients might be questionable. However, a Class I sample without orthodontic Tx need at adolescence and no history of orthodontic Tx can be regarded as a ‘natural’ gold standard for occlusal development and therefore represent a more realistic control group than a sample exhibiting an ideal occlusion (PAR score 0). Such a group, in contrast, would neither correspond to nor reflect the natural aging processes of the human dentition (17, 19). Furthermore, it should be considered that the treated Class II:2 patients were Class I after Tx, and therefore shared the same long-term occlusal predispositions as the untreated Class I control group. Method To assess the outcome quality objectively and gain long-term stability data, the PAR index was used. The PAR index has been shown to be a reliable and valid assessment method (20, 21). However, as there has also been criticism for the weighting system (22) and problems regarding the interpretation (23), the investigational plan of the present investigation comprised additional occlusal variables. Due to the rather small sample size, no further subgroup analyses were performed. Improvement of occlusal parameters during active Tx As expected, the Class II:2 sample showed notably higher values for both the occlusal variables as well as the total PAR index when compared to the untreated Class I controls at T0. However, the average total PAR score (Table 3) was as low as 15.0 ± 7.0 in the Class II:2 before Tx (T0), which means that the majority of patients were not eligible to be categorized as ‘greatly improved’ in terms of PAR score reduction, no matter how excellent the final Tx outcome was. This is another PAR index feature which might be criticised. However, looking at the changes during active Tx (T1–T0; Supplementary Tables 3 and 5), notable differences (P < 0.01) can be seen for the occlusal variables as well as the total PAR score between the treated Class II:2 sample and the Class I controls. So, obviously due to orthodontic Tx, the situation had reversed by T1, as identical to lower values were seen for the occlusal variables as well as the PAR index in the treated Class II:2 sample (P = 0.000–0.891) when compared to the untreated Class I controls (Table 3). Long-term post-Tx changes Rating the changes which occurred during the post-Tx observation period (T3–T1), however, the findings at T1 and T3 should be considered. While the treated Class II:2 patients exhibited slightly overcompensated and more ‘perfect’ values regarding overbite, overjet and alignment at T1 when compared with the untreated controls, the condition at T3 was more ‘normal’ and comparable to the controls. Statistically notable (P < 0.01) but most likely clinically irrelevant differences between the treated Class II:2 sample and the untreated Class I controls existed for overjet (2.2 versus 3.2 mm; Table 3) and total PAR score (5.9 points versus 8.9 points; Table 3). While the changes during the long-term observation period T3–T1 correspond to minor relapse in the treated Class II:2 sample and exceed those of the controls, the findings at T3 are still similar or slightly better than in the untreated Class I sample. However, rating these changes, it has to be taken into account that 8 of the 20 participants still wore fixed lower canine-to-canine retainers at T3. In order to compare the present findings to changes in other populations, the literature was searched for respective data from long-term observations; however, as almost no Class II:2 specific data exist, Class I and unspecified Class II samples were used for comparison. Regarding sagittal occlusal relationship, an increase of 1.5 mm towards Class II was reported after a recall of Class II:2 patients 20 years after Tx with activators (12). Changes of 0.1–1.1 mm were seen in 72 Classes I and II recall patients 12–35 years after fixed appliance Tx with/without extractions (24), while a Class I molar relationship with proper cusp-to-groove interdigitation was determined to be stable in all of 69 untreated subjects (25). The current findings are alike (treated Class II:2 sample: mean 0.1 ± 0.2 cw, controls: 0.0 ± 0.1 cw). After fixed appliance Tx, Class II:2 patients exhibited mean overbite increases of 1.2–1.4 mm 15 years after Tx (13) and 5 years after the end of retention (15), respectively. The mean long-term post-Tx increases (≥12 years) reported in the literature for Class I and unspecified Class II samples range between 0.5 and 1.6 mm (24, 26–30). So, the values in the literature are similar to the present findings (1.3 mm), which is also true for the untreated controls: −0.3 mm (present investigation) versus −0.1 to −0.3 mm (26, 31). In terms of overjet, a mean increase of 0.3 mm was seen in Class II:2 patients 15 years after fixed appliance Tx (13) and 5 years after the end of retention 15), respectively. These data correspond well with the average overjet increase of 0.5 mm (Class II:2) and 0.0 mm (controls), respectively, determined in the present investigation as well as in corresponding untreated populations (−0.2 to 0.1 mm; 26, 31). Only few data regarding long-term PAR score changes are available in the literature. For Class II:2 patients, an increase by 3.3 points with a final value of 6.7 points was reported 20 years after Tx with activators (12). Several unspecified patient samples (mixed Class I and II as well as Tx procedures with and without extractions) exhibited mean post-Tx increases of 5.1–7.6 points between age ~15 and 10–16 years later (32–34). The present results show slightly more favourable values but it has to be taken into account that 8 of the 20 study participants (=40%) still wore bonded lower canine-to-canine retainers at T3. The long-term wear of bonded retainers was found to result in approximately 5 points lower total PAR scores in the respective patients when compared to those not wearing retainers (33, 34). In the present investigation, the difference was slightly lower (2.4 points; Table 4). However, evaluating these data, it should be kept in mind that the respective subgroups were rather small (8 vs. 12 patients). For untreated Class I controls, the literature reports a PAR score increase from 11.9 points at age 12–12.9 points at age 22 (34). In the present investigation slightly lower values were seen (8.8 at age 15 and 8.9 at age 33) even if the determined long-term increase is comparable. So, in summary, long-term Class II:2 stability in the present Herbst-MBA sample was remarkably good. Thus, Class II:2 stability seems to be far better than its reputation. Strengths and limitations The present investigation adds to the, so far limited, data on long-term changes after Class II:2 Tx. The outcome quality was assessed in a patient sample which had been treated by a standardized Tx approach using both objective and subjective variables and comparing the respective data to untreated Class I controls. The Class II:2 sample, however, bears some limitations. The participants were neither treated at exactly the same age or skeletal maturity nor at the same time period. In addition, the retention protocol and retainer wear until study participation was not equal. However, a narrow age range prevails and the participants can be considered alike. The participation rate was only 61% but this seems to be adequate due to the long-term design. No untreated or comparable treated Class II:2 sample with similar long-term data was available and unfortunately the assessed untreated Class I control sample was generated at a different site in Europe; nevertheless, the complete sample was of Caucasian descent as the Class II:2 sample. Of course it would have been favourable to assess the long-term post-Tx changes more intensively by evaluating additional study models from further in-between examinations. This is also true for lateral cephalograms, which, however, did not exist. Regarding the assessment method, no blinding was undertaken as the study models of the two samples were generated at different sites and time periods making them clearly distinguishable. Conclusion A very good long-term stability was seen for the occlusal outcome of Class II:2 Herbst-MBA Tx. On average mild changes had occurred during the post-Tx observation period and the long-term findings were similar as in untreated Class I controls. Supplementary material Supplementary material is available at European Journal of Orthodontics online. Funding The study was financially supported by the German Society of Dentistry and Oral Medicine (DGZMK); this comprised fees for insurances, participants’ compensation and travel expenses as well as consumables. DR was supported by the Research Foundation of Helsinki University Hospital and Academy of Finland grant 257472. Conflict of interest The authors declare no conflict of interest. Notes Editors’ comment: As is the case with all submissions to the EJO, this manuscript went through a double blinded submission and review process. This meant that the reviewers were blinded from the authors’ identity and the authors were blinded from the submission process including reviewers’ identity. As a co-author of this publication this blinding also applied to David Rice Editor of the EJO. References 1. Canut , J.A. and Arias , S . ( 1999 ) A long-term evaluation of treated Class II division 2 malocclusions: a retrospective study model analysis . European Journal of Orthodontics , 21 , 377 – 386 . Google Scholar CrossRef Search ADS PubMed 2. Selwyn-Barnett , B.J . ( 1991 ) Rationale of treatment for Class II division 2 malocclusion . British Journal of Orthodontics , 18 , 173 – 181 . Google Scholar CrossRef Search ADS PubMed 3. Ingervall , B. , Seemann , L. and Thilander , B . ( 1972 ) Frequency of malocclusion and need of orthodontic treatment in 10-year-old children in Gothenburg . Svensk Tandläkare-Tidskrift , 65 , 7 – 21 . 4. Mierut , L.L . ( 2000 ) Class II division 2 malocclusions: frequency and upper incisor aspects [abstract] . European Journal of Orthodontics , 22 , 602 . 5. Millett , D.T. , Cunningham , S.J. , O’Brien , K.D. , Benson , P.E. and de Oliveira , C.M . ( 2012 ) Treatment and stability of Class II division 2 malocclusion in children and adolescents: a systematic review . American Journal of Orthodontics and Dentofacial Orthopedics , 142 , 159 – 169 . Google Scholar CrossRef Search ADS PubMed 6. Bock , N.C. and Ruf , S . ( 2013 ) Class II division 2 treatment--does skeletal maturity influence success and stability ? Journal of Orofacial Orthopedics , 74 , 187 – 4204 . Google Scholar CrossRef Search ADS PubMed 7. Eberhard , H. and Hirschfelder , U . ( 1998 ) Treatment of Class II division 2 in the late growth period . Fortschritte der Kieferorthopädie , 59 , 352 – 361 . Google Scholar CrossRef Search ADS PubMed 8. Marku , K . ( 2006 ) Die Klasse II/2 Behandlung bei Postadoleszenten und jungen Erwachsenen mit der Herbst-/Multibracket-Apparatur . Thesis, University of Giessen , Germany . 9. Obijou , C. and Pancherz , H . ( 1997 ) Herbst appliance treatment of Class II division 2 malocclusions . American Journal of Orthodontics and Dentofacial Orthopedics , 112 , 287 – 291 . Google Scholar CrossRef Search ADS PubMed 10. Bock , N. and Ruf , S . ( 2008 ) Post-treatment occlusal changes in Class II division 2 subjects treated with the Herbst appliance . European Journal of Orthodontics , 30 , 606 – 613 . Google Scholar CrossRef Search ADS PubMed 11. Bock , N.C. , von Bremen , J. and Ruf , S . ( 2016 ) Stability of Class II fixed functional appliance therapy–a systematic review and meta-analysis . European Journal of Orthodontics , 38 , 129 – 139 . Google Scholar CrossRef Search ADS PubMed 12. Ferrazzini G . ( 2008 ) Class II/2 malocclusion: Early treatment with removable appliances and stability after 20 years . Schweiz Monatsschrift fuer Zahnmedizin , 118 , 814 – 819 . 13. Kim , T.W. and Little , R.M . ( 1999 ) Postretention assessment of deep overbite correction in Class II Division 2 malocclusion . The Angle Orthodontist , 69 , 175 – 186 . Google Scholar PubMed 14. Al Yami E.A . ( 1997 ) Orthodontics: treatment need and treatment outcome . Dissertation, University of Nijmegen , Netherlands . 15. Binda , S.K. , Kuijpers-Jagtman , A.M. , Maertens , J.K. and van ‘t Hof , M.A . ( 1994 ) A long-term cephalometric evaluation of treated Class II division 2 malocclusions . European Journal of Orthodontics , 16 , 301 – 308 . Google Scholar CrossRef Search ADS PubMed 16. Richmond , S. , Shaw , W.C. , Roberts , C.T. and Andrews , M . ( 1992 ) The PAR Index (Peer Assessment Rating): methods to determine outcome of orthodontic treatment in terms of improvement and standards . European Journal of Orthodontics , 14 , 180 – 187 . Google Scholar CrossRef Search ADS PubMed 17. Heikinheimo , K. , Nyström , M. , Heikinheimo , T. , Pirttiniemi , P. and Pirinen , S . ( 2012 ) Dental arch width, overbite, and overjet in a Finnish population with normal occlusion between the ages of 7 and 32 years . European Journal of Orthodontics , 34 , 418 – 426 . Google Scholar CrossRef Search ADS PubMed 18. Tukey J.W . ( 1977 ) Exploratory Data Analysis . Addison-Wesley Publishing Company , Reading, PA . 19. Henrikson , J. , Persson , M. and Thilander , B . ( 2001 ) Long-term stability of dental arch form in normal occlusion from 13 to 31 years of age . European Journal of Orthodontics , 23 , 51 – 61 . Google Scholar CrossRef Search ADS PubMed 20. Buchanan , I.B. , Shaw , W.C. , Richmond , S. , O’Brien , K.D. and Andrews , M . ( 1993 ) A comparison of the reliability and validity of the PAR Index and Summers’ Occlusal Index . European Journal of Orthodontics , 15 , 27 – 31 . Google Scholar CrossRef Search ADS PubMed 21. Deguchi T. , Honjo T. , Fukunaga T. , Miyawaki S. , Roberts W.E. and Takano-Yamamoto T . ( 2005 ) Clinical assessment of orthodontic outcomes with the peer assessment rating, discrepancy index, objective grading system, and comprehensive clinical assessment . American Journal of Orthodontics and Dentofacial Orthopedics , 127 , 434 – 443 . Google Scholar CrossRef Search ADS PubMed 22. Hamdan , A.M. and Rock , W.P . ( 1999 ) An appraisal of the Peer Assessment Rating (PAR) Index and a suggested new weighting system . European Journal of Orthodontics , 21 , 181 – 192 . Google Scholar CrossRef Search ADS PubMed 23. Buchanan , I.B. , Russell , J.I. and Clark , J.D . ( 1996 ) Practical application of the PAR index: an illustrative comparison of the outcome of treatment using two fixed appliance techniques . British Journal of Orthodontics , 23 , 351 – 357 . Google Scholar CrossRef Search ADS PubMed 24. Uhde , M.D. , Sadowsky , C. and BeGole , E.A . ( 1983 ) Long-term stability of dental relationships after orthodontic treatment . The Angle Orthodontist , 53 , 240 – 252 . Google Scholar PubMed 25. Harris , E.F. and Behrents , R.G . ( 1988 ) The intrinsic stability of Class I molar relationship: A longitudinal study of untreated cases . American Journal of Orthodontics and Dentofacial Orthopedics , 94 , 63 – 67 . Google Scholar CrossRef Search ADS PubMed 26. Driscoll-Gilliland , J. , Buschang , P.H. and Behrents , R.G . ( 2001 ) An evaluation of growth and stability in untreated and treated subjects . American Journal of Orthodontics and Dentofacial Orthopedics , 120 , 588 – 597 . Google Scholar CrossRef Search ADS PubMed 27. Dyer , K.C. , Vaden , J.L. and Harris , E.F . ( 2012 ) Relapse revisited–again . American Journal of Orthodontics and Dentofacial Orthopedics , 142 , 221 – 227 . Google Scholar CrossRef Search ADS PubMed 28. Haruki , T. and Little , R.M . ( 1998 ) Early versus late treatment of crowded first premolar extraction cases: postretention evaluation of stability and relapse . The Angle Orthodontist , 68 , 61 – 68 . Google Scholar PubMed 29. Myser , S.A. , Campbell , P.M. , Boley , M. and Buschang , P.H . ( 2013 ) Long-term stability: Postretention changes of the mandibular anterior teeth . American Journal of Orthodontics and Dentofacial Orthopedics , 144 , 420 – 429 . Google Scholar CrossRef Search ADS PubMed 30. Schütz-Fransson , U. , Lindsten , R. , Bjerklin , K. and Bondemark , L . ( 2017 ) Twelve-year follow-up of mandibular incisor stability: Comparison between two bonded lingual orthodontic retainers . The Angle Orthodontist , 87 , 200 – 208 . Google Scholar CrossRef Search ADS PubMed 31. Thilander , B . ( 2009 ) Dentoalveolar development in subjects with normal occlusion. A longitudinal study between the ages of 5 and 31 years . European Journal of Orthodontics , 31 , 109 – 120 . Google Scholar CrossRef Search ADS PubMed 32. Zinad , K. , Schols , A.M. and Schols , J.G . ( 2016 ) Another way of looking at treatment stability . The Angle Orthodontist , 86 , 721 – 726 . Google Scholar CrossRef Search ADS PubMed 33. Lagerström , L. , Fornell , A.C. and Stenvik , A . ( 2011 ) Outcome of a scheme for specialist orthodontic care, a follow-up study in 31-year-olds . Swedish Dental Journal , 35 , 41 – 47 . Google Scholar PubMed 34. Al Yami , E.A. , Kuijpers-Jagtman , A.M. and van’t Hof , M.A . ( 1999 ) Stability of orthodontic treatment outcome: Follow-up until 10 years postretention . American Journal of Orthodontics and Dentofacial Orthopedics , 115 , 300 – 304 . Google Scholar CrossRef Search ADS PubMed © The Author(s) 2017. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The European Journal of Orthodontics Oxford University Press

Outcome quality and long-term (≥15 years) stability after Class II:2 Herbst-multibracket appliance treatment in comparison to untreated Class I controls

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© The Author(s) 2017. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com
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Abstract

Summary Aim To investigate the outcome quality and the long-term (≥15 years) post-treatment (Tx) changes after Class II:2 Herbst-multibracket appliance (MBA) Tx. Subjects and Methods In this longitudinal observational study, a recall of Class II:2 patients who had been treated by a Herbst-MBA during adolescence was conducted. Study models from before and after active Tx, after retention and after recall were assessed using standard occlusal variables and the peer assessment rating index (PAR). These data were compared to historical untreated Class I controls. Results Twenty out of 33 patients (61%) could be located and participated at age 33.9 ± 2.7 years. When comparing their data to the 13 patients who did not participate, the pre- and post-Tx occlusal findings did not differ systematically; however, the PAR scores of the non-participants were by 3.3–8.2 points higher at all times and the non-participants were 2.1–2.5 years older. Pre-Tx at age 14.4 ± 2.7 years, the participants showed the following mean values: PAR = 15.0 ± 7.0, Class II molar relationship (MR) = 0.8 ± 0.3 cusp widths (cw), overbite = 5.3 ± 1.3 mm. After Tx, a PAR score of 2.9 ± 1.3 and a super Class I MR (−0.1 ± 0.1 cw) with normal overbite (1.2 ± 0.8 mm) existed. At recall, a PAR score increase to 5.9 ± 3.6 points had occurred, mainly caused by an increase of overbite to 2.5 ± 1.5 mm. The average MR remained Class I (0.0 ± 0.2 cw). For all variables, the untreated controls exhibited similar findings. Conclusion The occlusal outcome of Class II:2 Herbst-MBA Tx exhibited very good long-term stability. While mild post-Tx changes occurred, the long-term findings are similar to untreated Class I controls. Introduction Class II:2 malocclusions are said to be difficult to treat and to have a high risk for relapse (1, 2). For children in European populations, prevalences of up to 10% have been reported for this malocclusion (3, 4). Although a systematic review concluded that only highly biased evidence existed with regard to the effectiveness of Class II:2 therapy and the stability of the respective treatment (Tx) results (5), several retrospective investigations have shown Herbst-multibracket appliance (MBA) Tx to be most effective in terms of Class II:2 correction (6–9). Furthermore, the occlusal correction achieved by Herbst-MBA Tx was found to be relatively stable 2 years post-treatment (10). However, to date no evidence is available in terms of long-term stability (11), which is also true for most other Tx approaches used for Class II:2 correction. The only existing long-term data (≥15 years) deal with a sample of 18 patients after early Tx with activators (12) on the one hand, and a sample of 62 patients after fixed appliance Tx on the other hand (13). Additional publications (n = 66 and n = 44) report data from 5 years out of retention after fixed appliance Tx (14, 15). The degree of stability reported in these papers ranges between remarkably and moderately stable and shows large variability. No comparison to an untreated sample was made in any of the above mentioned papers Due to the specific aetiology and controversial stability reputation of Class II:2 malocclusions, it seems to be of particular interest to determine additional data and eventually reveal a Tx approach enabling successful and long-term stable correction of this type of malocclusion. Therefore, the aim of the present investigation was to assess the outcome quality and the long-term (≥15 years) post-Tx changes after Class II:2 Herbst-MBA Tx compared to untreated controls. Subjects and methods After obtaining ethical approval (Nr. 146/13) and study registration (WHO: ID DRKS00006354), the archive of the Department of Orthodontics at the University of Giessen, Germany was searched for all Class II:2 patients (irrespective of Tx outcome) who had been treated with a Herbst-MBA and whose active Tx was finished at least 15 years ago. A total of 33 patients with a mean age of 14.4 years at the start of Tx were determined. All these patients had a Class II occlusal relationship (mean: 0.8 cusp widths) with the mandibular dentition being positioned posteriorly compared to the ‘normal’ Class I relationship. In addition, at least two maxillary incisors were retroclined and exhibited an anterior deep overbite (mean: 5.3 mm). Tx was carried out using a Herbst appliance Type I (Dentaurum®) as well as different types of labial straight-wire MBAs. In 14 of the 20 patients, the Tx protocol had started with 8.6 ± 5.6 months of fixed appliance Tx for upper incisor proclination to enable Herbst appliance insertion and adjustment in an incisal edge-to-edge relationship. In the remaining six patients, Tx could be started directly with the insertion of the Herbst appliance. The Herbst appliance was removed after 7.7 ± 1.7 months and replaced by a full arch MBA in both jaws in order to obtain proper occlusal settling and finishing. The total Tx duration amounted to 24.9 ± 6.9 months. All patients were treated non-extraction. Patient location and contact was attempted using the information in the patients’ records as well as the internet (search engines, online phone directories) as sources. While 27 of the potential 33 patients could be located and were asked to participate in the current investigation, 20 finally agreed and took part at age 33.9 ± 2.7 years. An informed consent was acquired from all participants before starting the examination. Impressions of the upper and lower arch as well as a wax bite were taken of all participants. In addition, study models in centric occlusion from before and after Tx as well as after retention were assessed and compared to the current findings in order to evaluate the changes that had occurred since the end of active Tx. The sagittal molar and canine relationships (right, left) as well as the overjet and the overbite were assessed for all occasions (T0: before Tx, T1: after Tx, T2: after retention, T3: recall). Visual ratings of the molar relationship were performed to the nearest 0.25 cusp widths (cw) and classified as Classes I, II, or III, while a manual calliper was used to accomplish linear measurements to the nearest 0.5 mm. In addition, the peer assessment rating index (PAR) (16) was utilised. A PAR-certified operator (N.B.) performed the respective ratings according to the respective guidelines (16) using an original PAR ruler. At recall (T3), no retainers at all were worn by 11 of the 20 participants; 4 of them had already been without retention at T2. Of the remaining nine participants, eight wore a lower bonded canine-to-canine retainer (seven bonded on the canines only, one bonded on all six teeth) while one participant had an upper bonded retainer only. Control group A ‘double negative, normal’ historical control group was used for comparison of the post-Tx changes. It was generated from a longitudinal study on growth changes in the dental arches in Finland which had followed the patients from age 7 years (17). The records obtained at age 12/13 years (T0), age 15 years (T1), and age 33 years (T3) were considered to correspond best to the current Herbst-MBA sample regarding age (Table 2). From all original Class I participants (17) with no orthodontic Tx need (n = 33), those who still exhibited a bilateral Class I relationship at the age of 15 years (which is more or less in concordance with the treated Class II:2 sample; Table 2) formed the untreated control group (n = 31) for the current investigation. Study models from both relevant time points T1 (age 15.4 ± 0.4 years) and T3 (age 32.9 ± 1.2 years) were available from all these untreated subjects (n = 31). Table 2. Comparison of the Class II:2 and the controls: the mean value (Mean), standard deviation (SD), and P value (P) of the respective group difference are given for age and the duration of the observation periods. Class II:2 Controls P (12♀:8♂) (17♀:14♂) Mean ± SD Mean ± SD Age T0 years 13.5 ± 1.95 13.0 ± 0.42 0.549 T1 15.7 ± 1.88 15.4 ± 0.36 0.787 T2 17.6 ± 2.24 — — T3 33.9 ± 2.67 32.9 ± 1.22 0.089 Observation period T1–T0 months 24.9 ± 6.91 29.3 ± 3.61 0.004 (Treatment) T2–T1 25.9 ± 10.81 — — (Retention) T3–T1 years 18.3 ± 2.44 17.5 ± 1.19 0.475 (Long-term) Class II:2 Controls P (12♀:8♂) (17♀:14♂) Mean ± SD Mean ± SD Age T0 years 13.5 ± 1.95 13.0 ± 0.42 0.549 T1 15.7 ± 1.88 15.4 ± 0.36 0.787 T2 17.6 ± 2.24 — — T3 33.9 ± 2.67 32.9 ± 1.22 0.089 Observation period T1–T0 months 24.9 ± 6.91 29.3 ± 3.61 0.004 (Treatment) T2–T1 25.9 ± 10.81 — — (Retention) T3–T1 years 18.3 ± 2.44 17.5 ± 1.19 0.475 (Long-term) —, data not available. View Large Table 2. Comparison of the Class II:2 and the controls: the mean value (Mean), standard deviation (SD), and P value (P) of the respective group difference are given for age and the duration of the observation periods. Class II:2 Controls P (12♀:8♂) (17♀:14♂) Mean ± SD Mean ± SD Age T0 years 13.5 ± 1.95 13.0 ± 0.42 0.549 T1 15.7 ± 1.88 15.4 ± 0.36 0.787 T2 17.6 ± 2.24 — — T3 33.9 ± 2.67 32.9 ± 1.22 0.089 Observation period T1–T0 months 24.9 ± 6.91 29.3 ± 3.61 0.004 (Treatment) T2–T1 25.9 ± 10.81 — — (Retention) T3–T1 years 18.3 ± 2.44 17.5 ± 1.19 0.475 (Long-term) Class II:2 Controls P (12♀:8♂) (17♀:14♂) Mean ± SD Mean ± SD Age T0 years 13.5 ± 1.95 13.0 ± 0.42 0.549 T1 15.7 ± 1.88 15.4 ± 0.36 0.787 T2 17.6 ± 2.24 — — T3 33.9 ± 2.67 32.9 ± 1.22 0.089 Observation period T1–T0 months 24.9 ± 6.91 29.3 ± 3.61 0.004 (Treatment) T2–T1 25.9 ± 10.81 — — (Retention) T3–T1 years 18.3 ± 2.44 17.5 ± 1.19 0.475 (Long-term) —, data not available. View Large Statistics In order to minimize the error of the method, all measurements and ratings were performed twice (N.B.) with a time interval of 2–4 weeks in between, and the mean value of both was utilised for further calculations. A non-normal distribution according to Shapiro–Wilk and Kolmogorov–Smirnov tests was seen for the majority of the data. Nevertheless, for the sake of comparison with other published data, the mean value and standard deviation are used throughout the text of the manuscript. However, in order to allow detailed interpretation, the median, minimum and maximum values are given in all respective tables. After performing a descriptive statistical analysis, the Mann–Whitney U test was applied for most group comparisons due to the non-normal distribution of the data. When comparing more than two groups, the Kruskal–Wallis test was used. Although the study followed an explorative design, a variety of inferential methods have been used to fully utilize the information in the data. The number of conducted tests adds up to a multiple testing situation (which leads to an accumulation of false positive results); being aware of this limitation, it was decided to regard P-values of up to 0.15 as hints of possible effects. This procedure was chosen as explorative data analysis does not use a fixed threshold value of probability to search for ‘patterns’ or ‘structure’ in experimental data although robust inferential statistical procedures are utilised (18). The 0.1–0.15 threshold was heuristically adapted from a selection process commonly used to screen for relevant factors in logistic regression and similar analytical procedures. Based on the properties of the measured parameters, the Intraclass Correlation Coefficient (ICC) was chosen to assess observer reliability for most variables. The ICC allows for examination of reliability of repeated measurements based on the exact agreement of the measurements. In contrast, for the ratings of all PAR index components, the consistency of measurements was assessed (Kendall’s Tau-b). While the ICC values were rather high for all measurements (mean: 0.9; standard deviation: 0.1; median: 0.9), the consistency values were slightly lower for the PAR components (mean: 0.7; standard deviation: 0.2; median: 0.7). Results Participants versus non-participants (Table 1, Figure 1, Supplementary Tables 1 and 2) As 20 of the 33 potential patients agreed to participate, the participation rate was 61% (with respect to the number of locatable patients). Nevertheless, 13 patients were not available for participation due to lack of interest or other reasons (Figure 1). Table 1. Comparison of the Class II:2 participants’ and non-participants’ data: the mean value (mean), standard deviation (SD) and P-value (P) of the respective group difference are given for age, duration of the observation periods, overbite, sagittal molar relationship, and PAR score. Participants Non-participants P (12♀:8♂) (5♀:8♂) Mean ± SD Mean ± SD Age T0 Years 13.5 ± 1.95 15.8 ± 3.04 0.013 T1 15.7 ± 1.88 17.8 ± 3.42 0.031 T2 17.6 ± 2.24 20.1 ± 4.04 0.057 Observation periods T1–T0 Months 24.9 ± 6.91 24.0 ± 7.95 0.738 (Treatment) T2–T1 25.9 ± 10.81 28.5 ± 12.01 0.184 (Retention) Molar relationship T0 cw 0.8 ± 0.31 0.8 ± 0.16 0.784 T1 −0.1 ± 0.12 0.0 ± 0.13 0.332 T2 0.0 ± 0.13 0.0 ± 0.15 0.187 Overbite T0 mm 5.3 ± 1.32 5.7 ± 2.14 0.519 T1 1.2 ± 0.77 1.4 ± 0.59 0.319 T2 2.3 ± 1.21 2.7 ± 1.06 0.309 PAR T0 Total score 15.0 ± 6.95 23.2 ± 7.29 0.019 T1 2.9 ± 1.33 6.2 ± 2.79 0.002 T2 3.1 ± 2.00 6.6 ± 2.53 0.001 Participants Non-participants P (12♀:8♂) (5♀:8♂) Mean ± SD Mean ± SD Age T0 Years 13.5 ± 1.95 15.8 ± 3.04 0.013 T1 15.7 ± 1.88 17.8 ± 3.42 0.031 T2 17.6 ± 2.24 20.1 ± 4.04 0.057 Observation periods T1–T0 Months 24.9 ± 6.91 24.0 ± 7.95 0.738 (Treatment) T2–T1 25.9 ± 10.81 28.5 ± 12.01 0.184 (Retention) Molar relationship T0 cw 0.8 ± 0.31 0.8 ± 0.16 0.784 T1 −0.1 ± 0.12 0.0 ± 0.13 0.332 T2 0.0 ± 0.13 0.0 ± 0.15 0.187 Overbite T0 mm 5.3 ± 1.32 5.7 ± 2.14 0.519 T1 1.2 ± 0.77 1.4 ± 0.59 0.319 T2 2.3 ± 1.21 2.7 ± 1.06 0.309 PAR T0 Total score 15.0 ± 6.95 23.2 ± 7.29 0.019 T1 2.9 ± 1.33 6.2 ± 2.79 0.002 T2 3.1 ± 2.00 6.6 ± 2.53 0.001 cw, cusp widths. View Large Table 1. Comparison of the Class II:2 participants’ and non-participants’ data: the mean value (mean), standard deviation (SD) and P-value (P) of the respective group difference are given for age, duration of the observation periods, overbite, sagittal molar relationship, and PAR score. Participants Non-participants P (12♀:8♂) (5♀:8♂) Mean ± SD Mean ± SD Age T0 Years 13.5 ± 1.95 15.8 ± 3.04 0.013 T1 15.7 ± 1.88 17.8 ± 3.42 0.031 T2 17.6 ± 2.24 20.1 ± 4.04 0.057 Observation periods T1–T0 Months 24.9 ± 6.91 24.0 ± 7.95 0.738 (Treatment) T2–T1 25.9 ± 10.81 28.5 ± 12.01 0.184 (Retention) Molar relationship T0 cw 0.8 ± 0.31 0.8 ± 0.16 0.784 T1 −0.1 ± 0.12 0.0 ± 0.13 0.332 T2 0.0 ± 0.13 0.0 ± 0.15 0.187 Overbite T0 mm 5.3 ± 1.32 5.7 ± 2.14 0.519 T1 1.2 ± 0.77 1.4 ± 0.59 0.319 T2 2.3 ± 1.21 2.7 ± 1.06 0.309 PAR T0 Total score 15.0 ± 6.95 23.2 ± 7.29 0.019 T1 2.9 ± 1.33 6.2 ± 2.79 0.002 T2 3.1 ± 2.00 6.6 ± 2.53 0.001 Participants Non-participants P (12♀:8♂) (5♀:8♂) Mean ± SD Mean ± SD Age T0 Years 13.5 ± 1.95 15.8 ± 3.04 0.013 T1 15.7 ± 1.88 17.8 ± 3.42 0.031 T2 17.6 ± 2.24 20.1 ± 4.04 0.057 Observation periods T1–T0 Months 24.9 ± 6.91 24.0 ± 7.95 0.738 (Treatment) T2–T1 25.9 ± 10.81 28.5 ± 12.01 0.184 (Retention) Molar relationship T0 cw 0.8 ± 0.31 0.8 ± 0.16 0.784 T1 −0.1 ± 0.12 0.0 ± 0.13 0.332 T2 0.0 ± 0.13 0.0 ± 0.15 0.187 Overbite T0 mm 5.3 ± 1.32 5.7 ± 2.14 0.519 T1 1.2 ± 0.77 1.4 ± 0.59 0.319 T2 2.3 ± 1.21 2.7 ± 1.06 0.309 PAR T0 Total score 15.0 ± 6.95 23.2 ± 7.29 0.019 T1 2.9 ± 1.33 6.2 ± 2.79 0.002 T2 3.1 ± 2.00 6.6 ± 2.53 0.001 cw, cusp widths. View Large Figure 1. View largeDownload slide Flow chart of the study participants/non-participants of the Class II:2 sample. The numbers of total Herbst-MBA patients (active Tx completed by January, 1st 2015) as well as potential participants and the results of the recruitment process are given. Figure 1. View largeDownload slide Flow chart of the study participants/non-participants of the Class II:2 sample. The numbers of total Herbst-MBA patients (active Tx completed by January, 1st 2015) as well as potential participants and the results of the recruitment process are given. Without any known reason, the 20 participants and the 13 non-participants of the Class II:2 sample differed by about 2 years in terms of age before Tx, after Tx, and after retention (P = 0.013–0.057). However, the duration of both the treatment (T1–T0) and retention periods was similar (P = 0.184–0.738). Although the classical Class II:2 malocclusion characteristics (Class II molar relationship, overbite) did not differ systematically at any time the mean PAR score values were by 3.3–8.2 points lower in the participants at all three examination time points (P = 0.001–0.019). Participants versus controls (Table 2) The only notable difference between the Class II:2 participants and the controls was the length of the observation period (T1–T0), which was by 5 months longer in the controls (24.9 versus 29.3 months, P = 0.004). Tx and long-term post-Tx changes (Table 3, Supplementary Tables 1–5, Figure 2, Supplementary Figure 1) As anticipated, at T0 marked differences existed between the Class II:2 participants and the untreated Class I controls for molar and canine relationships as well as for overbite and PAR score (Table 3, Supplementary Table 4, Figure 2). Table 3. Sagittal molar and canine relationships (mean left/right) as well as overbite, overjet, and the total PAR score in the Class II:2 and the controls at T0, T1, and T3. T0 T1 T3 Mean SD Min Max Med P Mean SD Min Max Med P Mean SD Min Max Med P Molar relationship cw Class II:2 0.8 0.31 0.3 1.3 0.8 0.000 −0.1 0.12 −0.3 0.2 −0.1 0.891 0.0 0.15 −0.3 0.4 0.0 0.101 Controls 0.0 0.16 −0.3 0.4 0.0 −0.1 0.15 −0.3 0.3 −0.1 −0.1 0.12 −0.3 0.3 −0.1 Canine relationship cw Class II:2 0.6 0.14 0.4 0.8 0.7 0.000 0.2 0.09 0.0 0.3 0.2 0.188 0.2 0.12 −0.1 0.3 0.2 0.875 Controls 0.3 0.12 0.0 0.5 0.3 0.2 0.10 0.0 0.5 0.3 0.2 0.12 0.0 0.4 0.1 Overbite mm Class II:2 5.3 1.32 3.5 9.0 5.0 0.000 1.2 0.77 0.3 2.5 1.0 0.000 2.5 1.49 0.0 5.3 2.1 0.885 Controls 2.7 0.88 1.3 4.0 2.8 2.7 0.96 1.0 4.8 2.5 2.4 1.21 0.5 4.5 2.3 Overjet mm Class II:2 4.1 1.70 1.8 7.0 3.8 0.422 1.8 0.61 0.5 2.8 1.8 0.000 2.2 0.85 0.0 3.8 2.3 0.001 Controls 3.6 0.83 1.5 4.8 3.5 3.2 0.74 1.5 4.8 3.3 3.2 0.81 1.8 4.8 3.3 Total PAR score Class II:2 15.0 6.95 6.0 27.5 15.0 0.019 2.9 1.33 1.5 5.5 2.5 0.000 5.9 3.62 2.0 16.5 5.5 0.002 Controls 10.5 4.24 3.5 17.0 10.5 8.8 3.71 2.5 15.0 8.5 8.9 3.34 2.5 18.0 9.0 T0 T1 T3 Mean SD Min Max Med P Mean SD Min Max Med P Mean SD Min Max Med P Molar relationship cw Class II:2 0.8 0.31 0.3 1.3 0.8 0.000 −0.1 0.12 −0.3 0.2 −0.1 0.891 0.0 0.15 −0.3 0.4 0.0 0.101 Controls 0.0 0.16 −0.3 0.4 0.0 −0.1 0.15 −0.3 0.3 −0.1 −0.1 0.12 −0.3 0.3 −0.1 Canine relationship cw Class II:2 0.6 0.14 0.4 0.8 0.7 0.000 0.2 0.09 0.0 0.3 0.2 0.188 0.2 0.12 −0.1 0.3 0.2 0.875 Controls 0.3 0.12 0.0 0.5 0.3 0.2 0.10 0.0 0.5 0.3 0.2 0.12 0.0 0.4 0.1 Overbite mm Class II:2 5.3 1.32 3.5 9.0 5.0 0.000 1.2 0.77 0.3 2.5 1.0 0.000 2.5 1.49 0.0 5.3 2.1 0.885 Controls 2.7 0.88 1.3 4.0 2.8 2.7 0.96 1.0 4.8 2.5 2.4 1.21 0.5 4.5 2.3 Overjet mm Class II:2 4.1 1.70 1.8 7.0 3.8 0.422 1.8 0.61 0.5 2.8 1.8 0.000 2.2 0.85 0.0 3.8 2.3 0.001 Controls 3.6 0.83 1.5 4.8 3.5 3.2 0.74 1.5 4.8 3.3 3.2 0.81 1.8 4.8 3.3 Total PAR score Class II:2 15.0 6.95 6.0 27.5 15.0 0.019 2.9 1.33 1.5 5.5 2.5 0.000 5.9 3.62 2.0 16.5 5.5 0.002 Controls 10.5 4.24 3.5 17.0 10.5 8.8 3.71 2.5 15.0 8.5 8.9 3.34 2.5 18.0 9.0 For each variable, the mean value (Mean), standard deviation (SD), minimum (Min), maximum (Max), and median value (Med) as well as the P value (P) of the respective group difference are given. cw, cusp widths. View Large Table 3. Sagittal molar and canine relationships (mean left/right) as well as overbite, overjet, and the total PAR score in the Class II:2 and the controls at T0, T1, and T3. T0 T1 T3 Mean SD Min Max Med P Mean SD Min Max Med P Mean SD Min Max Med P Molar relationship cw Class II:2 0.8 0.31 0.3 1.3 0.8 0.000 −0.1 0.12 −0.3 0.2 −0.1 0.891 0.0 0.15 −0.3 0.4 0.0 0.101 Controls 0.0 0.16 −0.3 0.4 0.0 −0.1 0.15 −0.3 0.3 −0.1 −0.1 0.12 −0.3 0.3 −0.1 Canine relationship cw Class II:2 0.6 0.14 0.4 0.8 0.7 0.000 0.2 0.09 0.0 0.3 0.2 0.188 0.2 0.12 −0.1 0.3 0.2 0.875 Controls 0.3 0.12 0.0 0.5 0.3 0.2 0.10 0.0 0.5 0.3 0.2 0.12 0.0 0.4 0.1 Overbite mm Class II:2 5.3 1.32 3.5 9.0 5.0 0.000 1.2 0.77 0.3 2.5 1.0 0.000 2.5 1.49 0.0 5.3 2.1 0.885 Controls 2.7 0.88 1.3 4.0 2.8 2.7 0.96 1.0 4.8 2.5 2.4 1.21 0.5 4.5 2.3 Overjet mm Class II:2 4.1 1.70 1.8 7.0 3.8 0.422 1.8 0.61 0.5 2.8 1.8 0.000 2.2 0.85 0.0 3.8 2.3 0.001 Controls 3.6 0.83 1.5 4.8 3.5 3.2 0.74 1.5 4.8 3.3 3.2 0.81 1.8 4.8 3.3 Total PAR score Class II:2 15.0 6.95 6.0 27.5 15.0 0.019 2.9 1.33 1.5 5.5 2.5 0.000 5.9 3.62 2.0 16.5 5.5 0.002 Controls 10.5 4.24 3.5 17.0 10.5 8.8 3.71 2.5 15.0 8.5 8.9 3.34 2.5 18.0 9.0 T0 T1 T3 Mean SD Min Max Med P Mean SD Min Max Med P Mean SD Min Max Med P Molar relationship cw Class II:2 0.8 0.31 0.3 1.3 0.8 0.000 −0.1 0.12 −0.3 0.2 −0.1 0.891 0.0 0.15 −0.3 0.4 0.0 0.101 Controls 0.0 0.16 −0.3 0.4 0.0 −0.1 0.15 −0.3 0.3 −0.1 −0.1 0.12 −0.3 0.3 −0.1 Canine relationship cw Class II:2 0.6 0.14 0.4 0.8 0.7 0.000 0.2 0.09 0.0 0.3 0.2 0.188 0.2 0.12 −0.1 0.3 0.2 0.875 Controls 0.3 0.12 0.0 0.5 0.3 0.2 0.10 0.0 0.5 0.3 0.2 0.12 0.0 0.4 0.1 Overbite mm Class II:2 5.3 1.32 3.5 9.0 5.0 0.000 1.2 0.77 0.3 2.5 1.0 0.000 2.5 1.49 0.0 5.3 2.1 0.885 Controls 2.7 0.88 1.3 4.0 2.8 2.7 0.96 1.0 4.8 2.5 2.4 1.21 0.5 4.5 2.3 Overjet mm Class II:2 4.1 1.70 1.8 7.0 3.8 0.422 1.8 0.61 0.5 2.8 1.8 0.000 2.2 0.85 0.0 3.8 2.3 0.001 Controls 3.6 0.83 1.5 4.8 3.5 3.2 0.74 1.5 4.8 3.3 3.2 0.81 1.8 4.8 3.3 Total PAR score Class II:2 15.0 6.95 6.0 27.5 15.0 0.019 2.9 1.33 1.5 5.5 2.5 0.000 5.9 3.62 2.0 16.5 5.5 0.002 Controls 10.5 4.24 3.5 17.0 10.5 8.8 3.71 2.5 15.0 8.5 8.9 3.34 2.5 18.0 9.0 For each variable, the mean value (Mean), standard deviation (SD), minimum (Min), maximum (Max), and median value (Med) as well as the P value (P) of the respective group difference are given. cw, cusp widths. View Large Figure 2. View largeDownload slide Development of molar relationship, overbite, overjet, and total PAR score from T0 until T3 in the treated Class II:2 (Tx) and the controls. While the dotted lines suggest certain changes, it is unknown what exactly happened between the respective time points. Figure 2. View largeDownload slide Development of molar relationship, overbite, overjet, and total PAR score from T0 until T3 in the treated Class II:2 (Tx) and the controls. While the dotted lines suggest certain changes, it is unknown what exactly happened between the respective time points. The detailed values for overjet, overbite as well as molar and canine relationships at T0, T1, and T3 are given in Table 3 (T2 in Supplementary Table 1). The respective changes during the observation periods T1–T0 and T3–T1 are shown in Supplementary Table 3 as well as Figure 2. After Tx, the mean molar relationship was −0.1 cw at T1 and 0.0 cw at T3 in the Class II:2, while it was −0.1 cw (T1 and T3) in the controls (P = 0.101–0.891). The canine relationship showed a mean value of 0.2 cw at both occasions and in both groups (P = 0.188–0.875). The mean overbite was by 1.5 mm smaller in the Class II:2 sample than in the controls (P = 0.000) after Tx, while it was almost identical after the long-term observation (2.5 versus 2.4 mm; P = 0.885). For overjet, the values were by 1.0–1.4 mm smaller in the Class II:2 sample at both occasions (P = 0.000–0.001). The detailed scores for the PAR index (total score as well as contributing components) at T0, T1, and T3 are given in Supplementary Table 4 (T2 in Supplementary Table 2). The respective changes during the observation periods T1–T0 and T3–T1 are shown in Supplementary Table 5. Immediately after Tx (T1), the mean total PAR score was distinctly lower by 5.9 points (P = 0.000) in the Class II:2 when compared with the controls (Table 3). At T3 a difference of 3.0 points (P = 0.002) prevailed, which was mainly due to the differences for the maxillary and mandibular anterior segments exhibiting lower values (=better alignment) in the Class II:2 than in the controls: 0.8 versus 2.0 and 1.1 versus 2.5 points (P = 0.000; Supplementary Table 4). Looking at the percentage of patients exhibiting ‘perfect’ PAR component scores (=0), it is most stunning to see that a perfect score for ‘occlusion’ is completely absent in both groups at all occasions (Supplementary Figure 1). Generally, the lowest percentages existed at T0 (both groups), while at T1 most components in the Class II:2 exhibited a major improvement. After long-term observation (T3), the Class II:2 group presented a perfect overbite slightly less frequent than the controls (45% versus 61%) while similar prevalences were only seen for perfect centrelines (95% versus 90%). Notably more perfect scores were found in the Class II:2 participants when compared with the controls for overjet (95%/71%) and maxillary/mandibular anterior segments (45%/45% versus 6%/3%). Influence of bonded retainers (Table 4) As 8 of the 20 participants still wore a lower canine-to-canine retainer at T3, a separate comparison of these two subgroups and the controls was performed for the long-term changes (T3–T1) of the total PAR score as well as the components ‘ mandibular anterior’, overjet and overbite. A distinct group difference (P = 0.002) was seen for the total PAR score. The retainer group exhibited an increase by 1.6 ± 2.0 points, while the group without retainers showed an increase by 4.0 ± 3.5 points; in the controls, the total PAR score increased by 0.1 ± 2.9 points. Similar, but less pronounced differences (P = 0.009–0.313) were seen for the components “mandibular anterior” and overbite (Table 4). Table 4. Changes of the total PAR score as well as the (weighted) components mandibular anterior, overjet, and overbite during long-term observation (T3–T1) in the Class II:2 with no retainer in the lower jaw at T3 (n = 12), the Class II:2 wearing a bonded lower canine-to-canine retainer at T3 (n = 8) and the controls. Class II:2 Controls (n = 31) P No retainer at T3 (n = 12) Bonded lower retainer at T3 (n = 8) Mean SD Min Max Med Mean SD Min Max Med Mean SD Min Max Med Total PAR score changes 4.0 3.55 0.0 12.0 3.3 1.6 1.99 −0.5 5.0 1.3 0.1 3.09 −5.5 8.0 −0.5 0.002 PAR component changes Mandibular anterior 1.4 1.24 0.0 3.5 1.0 0.0 0.00 0.0 0.0 0.0 0.9 1.17 −1.0 3.5 0.5 0.009 Overjet 0.3 1.54 −3.0 3.0 0.0 0.4 1.06 0.0 3.0 0.0 −0.3 2.49 −6.0 6.0 0.0 0.662 Overbite 1.3 1.30 0.0 4.0 2.0 0.8 0.89 0.0 2.0 0.5 −0.1 1.29 −2.0 1.0 0.0 0.313 Class II:2 Controls (n = 31) P No retainer at T3 (n = 12) Bonded lower retainer at T3 (n = 8) Mean SD Min Max Med Mean SD Min Max Med Mean SD Min Max Med Total PAR score changes 4.0 3.55 0.0 12.0 3.3 1.6 1.99 −0.5 5.0 1.3 0.1 3.09 −5.5 8.0 −0.5 0.002 PAR component changes Mandibular anterior 1.4 1.24 0.0 3.5 1.0 0.0 0.00 0.0 0.0 0.0 0.9 1.17 −1.0 3.5 0.5 0.009 Overjet 0.3 1.54 −3.0 3.0 0.0 0.4 1.06 0.0 3.0 0.0 −0.3 2.49 −6.0 6.0 0.0 0.662 Overbite 1.3 1.30 0.0 4.0 2.0 0.8 0.89 0.0 2.0 0.5 −0.1 1.29 −2.0 1.0 0.0 0.313 View Large Table 4. Changes of the total PAR score as well as the (weighted) components mandibular anterior, overjet, and overbite during long-term observation (T3–T1) in the Class II:2 with no retainer in the lower jaw at T3 (n = 12), the Class II:2 wearing a bonded lower canine-to-canine retainer at T3 (n = 8) and the controls. Class II:2 Controls (n = 31) P No retainer at T3 (n = 12) Bonded lower retainer at T3 (n = 8) Mean SD Min Max Med Mean SD Min Max Med Mean SD Min Max Med Total PAR score changes 4.0 3.55 0.0 12.0 3.3 1.6 1.99 −0.5 5.0 1.3 0.1 3.09 −5.5 8.0 −0.5 0.002 PAR component changes Mandibular anterior 1.4 1.24 0.0 3.5 1.0 0.0 0.00 0.0 0.0 0.0 0.9 1.17 −1.0 3.5 0.5 0.009 Overjet 0.3 1.54 −3.0 3.0 0.0 0.4 1.06 0.0 3.0 0.0 −0.3 2.49 −6.0 6.0 0.0 0.662 Overbite 1.3 1.30 0.0 4.0 2.0 0.8 0.89 0.0 2.0 0.5 −0.1 1.29 −2.0 1.0 0.0 0.313 Class II:2 Controls (n = 31) P No retainer at T3 (n = 12) Bonded lower retainer at T3 (n = 8) Mean SD Min Max Med Mean SD Min Max Med Mean SD Min Max Med Total PAR score changes 4.0 3.55 0.0 12.0 3.3 1.6 1.99 −0.5 5.0 1.3 0.1 3.09 −5.5 8.0 −0.5 0.002 PAR component changes Mandibular anterior 1.4 1.24 0.0 3.5 1.0 0.0 0.00 0.0 0.0 0.0 0.9 1.17 −1.0 3.5 0.5 0.009 Overjet 0.3 1.54 −3.0 3.0 0.0 0.4 1.06 0.0 3.0 0.0 −0.3 2.49 −6.0 6.0 0.0 0.662 Overbite 1.3 1.30 0.0 4.0 2.0 0.8 0.89 0.0 2.0 0.5 −0.1 1.29 −2.0 1.0 0.0 0.313 View Large Discussion The present investigation is the first to evaluate the outcome quality and the long-term post-Tx changes after Class II:2 Tx in comparison to untreated controls. As the mechanism of Class II:2 correction using a Herbst-MBA as well as the nature (dental/skeletal) of relapse are well known and have been published before (6, 8, 9), an analysis of the effects emerging during each the Herbst and the subsequent MBA phase separately was considered unnecessary for the current investigation. Therefore, it was predetermined to concentrate on the post-Tx effects and the occlusal stability. Subjects: participants versus non-participants A recall of all eligible Class II:2 patients who had received active Tx at the study centre during the period 1986–2000 was performed. Despite this long-term period, a standardized Tx approach had been pursued in all these patients, even if several practitioners conditionally under supervision of two senior orthodontists were involved. Only one investigator undertook all investigation-relevant study model assessments. In contrast to the treated Class II:2 participants, the non-participants were on average 2.1–2.5 years older (P < 0.06) and exhibited by 3.3–8.2 points higher PAR scores (P < 0.02) at T0, T1, and T2. While this difference probably influences the external validity of the present results, uniform data was seen for Tx duration (T1–T0), length of the retention period (T2–T1), molar relationship, and overbite (T0, T1, T2). Therefore, it can be hypothesized that no relevant selection bias prevailed. Subjects: untreated controls The untreated Class I control group was quite uniform in terms of age at both T0 (13.0 ± 0.4 years) and T1 (15.4 ± 0.4 years), as the sample comprised of participants of a longitudinal study on growth changes in the dental arches (17). No orthodontic Tx need existed when they were enrolled in this original study at age 7 years; however, at age 15 years (T1 in the present investigation) some participants had developed minor crowding. After long-term observation, the variation in age had slightly increased until T3 (32.9 ± 1.2 years). Nevertheless, the total PAR score had been quite stable during the whole observation period (T0: 10.5 ± 4.2; T1: 8.8 ± 3.7; T3: 8.9 ± 3.3) The decrease during T1–T0 was mainly a result of overjet reduction (Supplementary Tables 3 and 5), which can be attributed to natural mandibular growth changes during this period (age 13–15) which includes the peak of the pubertal growth spurt. Validity of the control group Using an untreated Class I sample as control for treated Class II:2 patients might be questionable. However, a Class I sample without orthodontic Tx need at adolescence and no history of orthodontic Tx can be regarded as a ‘natural’ gold standard for occlusal development and therefore represent a more realistic control group than a sample exhibiting an ideal occlusion (PAR score 0). Such a group, in contrast, would neither correspond to nor reflect the natural aging processes of the human dentition (17, 19). Furthermore, it should be considered that the treated Class II:2 patients were Class I after Tx, and therefore shared the same long-term occlusal predispositions as the untreated Class I control group. Method To assess the outcome quality objectively and gain long-term stability data, the PAR index was used. The PAR index has been shown to be a reliable and valid assessment method (20, 21). However, as there has also been criticism for the weighting system (22) and problems regarding the interpretation (23), the investigational plan of the present investigation comprised additional occlusal variables. Due to the rather small sample size, no further subgroup analyses were performed. Improvement of occlusal parameters during active Tx As expected, the Class II:2 sample showed notably higher values for both the occlusal variables as well as the total PAR index when compared to the untreated Class I controls at T0. However, the average total PAR score (Table 3) was as low as 15.0 ± 7.0 in the Class II:2 before Tx (T0), which means that the majority of patients were not eligible to be categorized as ‘greatly improved’ in terms of PAR score reduction, no matter how excellent the final Tx outcome was. This is another PAR index feature which might be criticised. However, looking at the changes during active Tx (T1–T0; Supplementary Tables 3 and 5), notable differences (P < 0.01) can be seen for the occlusal variables as well as the total PAR score between the treated Class II:2 sample and the Class I controls. So, obviously due to orthodontic Tx, the situation had reversed by T1, as identical to lower values were seen for the occlusal variables as well as the PAR index in the treated Class II:2 sample (P = 0.000–0.891) when compared to the untreated Class I controls (Table 3). Long-term post-Tx changes Rating the changes which occurred during the post-Tx observation period (T3–T1), however, the findings at T1 and T3 should be considered. While the treated Class II:2 patients exhibited slightly overcompensated and more ‘perfect’ values regarding overbite, overjet and alignment at T1 when compared with the untreated controls, the condition at T3 was more ‘normal’ and comparable to the controls. Statistically notable (P < 0.01) but most likely clinically irrelevant differences between the treated Class II:2 sample and the untreated Class I controls existed for overjet (2.2 versus 3.2 mm; Table 3) and total PAR score (5.9 points versus 8.9 points; Table 3). While the changes during the long-term observation period T3–T1 correspond to minor relapse in the treated Class II:2 sample and exceed those of the controls, the findings at T3 are still similar or slightly better than in the untreated Class I sample. However, rating these changes, it has to be taken into account that 8 of the 20 participants still wore fixed lower canine-to-canine retainers at T3. In order to compare the present findings to changes in other populations, the literature was searched for respective data from long-term observations; however, as almost no Class II:2 specific data exist, Class I and unspecified Class II samples were used for comparison. Regarding sagittal occlusal relationship, an increase of 1.5 mm towards Class II was reported after a recall of Class II:2 patients 20 years after Tx with activators (12). Changes of 0.1–1.1 mm were seen in 72 Classes I and II recall patients 12–35 years after fixed appliance Tx with/without extractions (24), while a Class I molar relationship with proper cusp-to-groove interdigitation was determined to be stable in all of 69 untreated subjects (25). The current findings are alike (treated Class II:2 sample: mean 0.1 ± 0.2 cw, controls: 0.0 ± 0.1 cw). After fixed appliance Tx, Class II:2 patients exhibited mean overbite increases of 1.2–1.4 mm 15 years after Tx (13) and 5 years after the end of retention (15), respectively. The mean long-term post-Tx increases (≥12 years) reported in the literature for Class I and unspecified Class II samples range between 0.5 and 1.6 mm (24, 26–30). So, the values in the literature are similar to the present findings (1.3 mm), which is also true for the untreated controls: −0.3 mm (present investigation) versus −0.1 to −0.3 mm (26, 31). In terms of overjet, a mean increase of 0.3 mm was seen in Class II:2 patients 15 years after fixed appliance Tx (13) and 5 years after the end of retention 15), respectively. These data correspond well with the average overjet increase of 0.5 mm (Class II:2) and 0.0 mm (controls), respectively, determined in the present investigation as well as in corresponding untreated populations (−0.2 to 0.1 mm; 26, 31). Only few data regarding long-term PAR score changes are available in the literature. For Class II:2 patients, an increase by 3.3 points with a final value of 6.7 points was reported 20 years after Tx with activators (12). Several unspecified patient samples (mixed Class I and II as well as Tx procedures with and without extractions) exhibited mean post-Tx increases of 5.1–7.6 points between age ~15 and 10–16 years later (32–34). The present results show slightly more favourable values but it has to be taken into account that 8 of the 20 study participants (=40%) still wore bonded lower canine-to-canine retainers at T3. The long-term wear of bonded retainers was found to result in approximately 5 points lower total PAR scores in the respective patients when compared to those not wearing retainers (33, 34). In the present investigation, the difference was slightly lower (2.4 points; Table 4). However, evaluating these data, it should be kept in mind that the respective subgroups were rather small (8 vs. 12 patients). For untreated Class I controls, the literature reports a PAR score increase from 11.9 points at age 12–12.9 points at age 22 (34). In the present investigation slightly lower values were seen (8.8 at age 15 and 8.9 at age 33) even if the determined long-term increase is comparable. So, in summary, long-term Class II:2 stability in the present Herbst-MBA sample was remarkably good. Thus, Class II:2 stability seems to be far better than its reputation. Strengths and limitations The present investigation adds to the, so far limited, data on long-term changes after Class II:2 Tx. The outcome quality was assessed in a patient sample which had been treated by a standardized Tx approach using both objective and subjective variables and comparing the respective data to untreated Class I controls. The Class II:2 sample, however, bears some limitations. The participants were neither treated at exactly the same age or skeletal maturity nor at the same time period. In addition, the retention protocol and retainer wear until study participation was not equal. However, a narrow age range prevails and the participants can be considered alike. The participation rate was only 61% but this seems to be adequate due to the long-term design. No untreated or comparable treated Class II:2 sample with similar long-term data was available and unfortunately the assessed untreated Class I control sample was generated at a different site in Europe; nevertheless, the complete sample was of Caucasian descent as the Class II:2 sample. Of course it would have been favourable to assess the long-term post-Tx changes more intensively by evaluating additional study models from further in-between examinations. This is also true for lateral cephalograms, which, however, did not exist. Regarding the assessment method, no blinding was undertaken as the study models of the two samples were generated at different sites and time periods making them clearly distinguishable. Conclusion A very good long-term stability was seen for the occlusal outcome of Class II:2 Herbst-MBA Tx. On average mild changes had occurred during the post-Tx observation period and the long-term findings were similar as in untreated Class I controls. Supplementary material Supplementary material is available at European Journal of Orthodontics online. Funding The study was financially supported by the German Society of Dentistry and Oral Medicine (DGZMK); this comprised fees for insurances, participants’ compensation and travel expenses as well as consumables. DR was supported by the Research Foundation of Helsinki University Hospital and Academy of Finland grant 257472. Conflict of interest The authors declare no conflict of interest. Notes Editors’ comment: As is the case with all submissions to the EJO, this manuscript went through a double blinded submission and review process. This meant that the reviewers were blinded from the authors’ identity and the authors were blinded from the submission process including reviewers’ identity. As a co-author of this publication this blinding also applied to David Rice Editor of the EJO. References 1. Canut , J.A. and Arias , S . ( 1999 ) A long-term evaluation of treated Class II division 2 malocclusions: a retrospective study model analysis . European Journal of Orthodontics , 21 , 377 – 386 . Google Scholar CrossRef Search ADS PubMed 2. Selwyn-Barnett , B.J . ( 1991 ) Rationale of treatment for Class II division 2 malocclusion . British Journal of Orthodontics , 18 , 173 – 181 . Google Scholar CrossRef Search ADS PubMed 3. Ingervall , B. , Seemann , L. and Thilander , B . ( 1972 ) Frequency of malocclusion and need of orthodontic treatment in 10-year-old children in Gothenburg . Svensk Tandläkare-Tidskrift , 65 , 7 – 21 . 4. Mierut , L.L . ( 2000 ) Class II division 2 malocclusions: frequency and upper incisor aspects [abstract] . European Journal of Orthodontics , 22 , 602 . 5. Millett , D.T. , Cunningham , S.J. , O’Brien , K.D. , Benson , P.E. and de Oliveira , C.M . ( 2012 ) Treatment and stability of Class II division 2 malocclusion in children and adolescents: a systematic review . American Journal of Orthodontics and Dentofacial Orthopedics , 142 , 159 – 169 . Google Scholar CrossRef Search ADS PubMed 6. Bock , N.C. and Ruf , S . ( 2013 ) Class II division 2 treatment--does skeletal maturity influence success and stability ? Journal of Orofacial Orthopedics , 74 , 187 – 4204 . Google Scholar CrossRef Search ADS PubMed 7. Eberhard , H. and Hirschfelder , U . ( 1998 ) Treatment of Class II division 2 in the late growth period . Fortschritte der Kieferorthopädie , 59 , 352 – 361 . Google Scholar CrossRef Search ADS PubMed 8. Marku , K . ( 2006 ) Die Klasse II/2 Behandlung bei Postadoleszenten und jungen Erwachsenen mit der Herbst-/Multibracket-Apparatur . Thesis, University of Giessen , Germany . 9. Obijou , C. and Pancherz , H . ( 1997 ) Herbst appliance treatment of Class II division 2 malocclusions . American Journal of Orthodontics and Dentofacial Orthopedics , 112 , 287 – 291 . Google Scholar CrossRef Search ADS PubMed 10. Bock , N. and Ruf , S . ( 2008 ) Post-treatment occlusal changes in Class II division 2 subjects treated with the Herbst appliance . European Journal of Orthodontics , 30 , 606 – 613 . Google Scholar CrossRef Search ADS PubMed 11. Bock , N.C. , von Bremen , J. and Ruf , S . ( 2016 ) Stability of Class II fixed functional appliance therapy–a systematic review and meta-analysis . European Journal of Orthodontics , 38 , 129 – 139 . Google Scholar CrossRef Search ADS PubMed 12. Ferrazzini G . ( 2008 ) Class II/2 malocclusion: Early treatment with removable appliances and stability after 20 years . Schweiz Monatsschrift fuer Zahnmedizin , 118 , 814 – 819 . 13. Kim , T.W. and Little , R.M . ( 1999 ) Postretention assessment of deep overbite correction in Class II Division 2 malocclusion . The Angle Orthodontist , 69 , 175 – 186 . Google Scholar PubMed 14. Al Yami E.A . ( 1997 ) Orthodontics: treatment need and treatment outcome . Dissertation, University of Nijmegen , Netherlands . 15. Binda , S.K. , Kuijpers-Jagtman , A.M. , Maertens , J.K. and van ‘t Hof , M.A . ( 1994 ) A long-term cephalometric evaluation of treated Class II division 2 malocclusions . European Journal of Orthodontics , 16 , 301 – 308 . Google Scholar CrossRef Search ADS PubMed 16. Richmond , S. , Shaw , W.C. , Roberts , C.T. and Andrews , M . ( 1992 ) The PAR Index (Peer Assessment Rating): methods to determine outcome of orthodontic treatment in terms of improvement and standards . European Journal of Orthodontics , 14 , 180 – 187 . Google Scholar CrossRef Search ADS PubMed 17. Heikinheimo , K. , Nyström , M. , Heikinheimo , T. , Pirttiniemi , P. and Pirinen , S . ( 2012 ) Dental arch width, overbite, and overjet in a Finnish population with normal occlusion between the ages of 7 and 32 years . European Journal of Orthodontics , 34 , 418 – 426 . Google Scholar CrossRef Search ADS PubMed 18. Tukey J.W . ( 1977 ) Exploratory Data Analysis . Addison-Wesley Publishing Company , Reading, PA . 19. Henrikson , J. , Persson , M. and Thilander , B . ( 2001 ) Long-term stability of dental arch form in normal occlusion from 13 to 31 years of age . European Journal of Orthodontics , 23 , 51 – 61 . Google Scholar CrossRef Search ADS PubMed 20. Buchanan , I.B. , Shaw , W.C. , Richmond , S. , O’Brien , K.D. and Andrews , M . ( 1993 ) A comparison of the reliability and validity of the PAR Index and Summers’ Occlusal Index . European Journal of Orthodontics , 15 , 27 – 31 . Google Scholar CrossRef Search ADS PubMed 21. Deguchi T. , Honjo T. , Fukunaga T. , Miyawaki S. , Roberts W.E. and Takano-Yamamoto T . ( 2005 ) Clinical assessment of orthodontic outcomes with the peer assessment rating, discrepancy index, objective grading system, and comprehensive clinical assessment . American Journal of Orthodontics and Dentofacial Orthopedics , 127 , 434 – 443 . Google Scholar CrossRef Search ADS PubMed 22. Hamdan , A.M. and Rock , W.P . ( 1999 ) An appraisal of the Peer Assessment Rating (PAR) Index and a suggested new weighting system . European Journal of Orthodontics , 21 , 181 – 192 . Google Scholar CrossRef Search ADS PubMed 23. Buchanan , I.B. , Russell , J.I. and Clark , J.D . ( 1996 ) Practical application of the PAR index: an illustrative comparison of the outcome of treatment using two fixed appliance techniques . British Journal of Orthodontics , 23 , 351 – 357 . Google Scholar CrossRef Search ADS PubMed 24. Uhde , M.D. , Sadowsky , C. and BeGole , E.A . ( 1983 ) Long-term stability of dental relationships after orthodontic treatment . The Angle Orthodontist , 53 , 240 – 252 . Google Scholar PubMed 25. Harris , E.F. and Behrents , R.G . ( 1988 ) The intrinsic stability of Class I molar relationship: A longitudinal study of untreated cases . American Journal of Orthodontics and Dentofacial Orthopedics , 94 , 63 – 67 . Google Scholar CrossRef Search ADS PubMed 26. Driscoll-Gilliland , J. , Buschang , P.H. and Behrents , R.G . ( 2001 ) An evaluation of growth and stability in untreated and treated subjects . American Journal of Orthodontics and Dentofacial Orthopedics , 120 , 588 – 597 . Google Scholar CrossRef Search ADS PubMed 27. Dyer , K.C. , Vaden , J.L. and Harris , E.F . ( 2012 ) Relapse revisited–again . American Journal of Orthodontics and Dentofacial Orthopedics , 142 , 221 – 227 . Google Scholar CrossRef Search ADS PubMed 28. Haruki , T. and Little , R.M . ( 1998 ) Early versus late treatment of crowded first premolar extraction cases: postretention evaluation of stability and relapse . The Angle Orthodontist , 68 , 61 – 68 . Google Scholar PubMed 29. Myser , S.A. , Campbell , P.M. , Boley , M. and Buschang , P.H . ( 2013 ) Long-term stability: Postretention changes of the mandibular anterior teeth . American Journal of Orthodontics and Dentofacial Orthopedics , 144 , 420 – 429 . Google Scholar CrossRef Search ADS PubMed 30. Schütz-Fransson , U. , Lindsten , R. , Bjerklin , K. and Bondemark , L . ( 2017 ) Twelve-year follow-up of mandibular incisor stability: Comparison between two bonded lingual orthodontic retainers . The Angle Orthodontist , 87 , 200 – 208 . Google Scholar CrossRef Search ADS PubMed 31. Thilander , B . ( 2009 ) Dentoalveolar development in subjects with normal occlusion. A longitudinal study between the ages of 5 and 31 years . European Journal of Orthodontics , 31 , 109 – 120 . Google Scholar CrossRef Search ADS PubMed 32. Zinad , K. , Schols , A.M. and Schols , J.G . ( 2016 ) Another way of looking at treatment stability . The Angle Orthodontist , 86 , 721 – 726 . Google Scholar CrossRef Search ADS PubMed 33. Lagerström , L. , Fornell , A.C. and Stenvik , A . ( 2011 ) Outcome of a scheme for specialist orthodontic care, a follow-up study in 31-year-olds . Swedish Dental Journal , 35 , 41 – 47 . Google Scholar PubMed 34. Al Yami , E.A. , Kuijpers-Jagtman , A.M. and van’t Hof , M.A . ( 1999 ) Stability of orthodontic treatment outcome: Follow-up until 10 years postretention . American Journal of Orthodontics and Dentofacial Orthopedics , 115 , 300 – 304 . Google Scholar CrossRef Search ADS PubMed © The Author(s) 2017. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com

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The European Journal of OrthodonticsOxford University Press

Published: Dec 9, 2017

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