Marginal quality of ceramic inlays after three different instrumental cavity preparation methods of the proximal boxes

Marginal quality of ceramic inlays after three different instrumental cavity preparation methods... Objectives The marginal quality of ceramic inlays was evaluated after the use of three different instrumental finishing methods in mesio-occluso-distal (mod) cavity boxes in vitro after hydrothermal loading (HTL). Materials and methods Caries-free human molars were divided into three groups. Mod-cavities were conventionally prepared. Box finishing was performed in every group with rotating (RI), sonic (SI), or ultrasonic (USI) instruments. Surface roughness was examined. Twelve mod-cavities remained untreated. Continuous margin quality was evaluated with scanning electron microscopy (SEM). Ceramic inlays were cemented into cavities. After HTL microleakage, marginal and absolute marginal gaps were examined. All data were analyzed statistically. Results Significant differences were found, between cavity surface roughness of RI and SI groups, the RI and USI groups, but not between microleakage, marginal, absolute marginal gaps after HTL and in proximal marginal quality. No correlations between microleakage and marginal gaps nor between microleakage and surface roughness were found. Conclusion Mod-cavity proximal box finishing with SI or USI resulted in a higher surface roughness than the use of RI. The type of the finishing method did not influence the marginal quality of ceramic inlays. For the mod-cavity finishing, the use of SI and USI could be an alternative instrumental method to conventional RI methods with a lower risk of iatrogenic damage of the adjacent teeth. Clinical relevance This study allows the practitioner to better determine the proper indications and limitations of the sonic and ultrasonic instruments for mod-cavity proximal box finishing. . . . . . . Keywords Surface roughness Microleakage Marginal gap Margin quality Ceramic inlays Finishing methods Hydrothermal wear Introduction dentistry, the long-term success is an actual problem [7]. Accordingly, information and discussion about the applica- Qualitative cavity preparation without discomfort is very im- tions and effects of the different instrumental methods of cav- portant in restorative dentistry [1]. The restoration geometry, ity preparation [1, 9], technical requirements, and the effective design considerations, preparation methods, and loading con- preparation of dental tissues [7] are in demand. ditions are key factors for the long-term success of dental According to the concept of Bminimally hazardous restorations [2–8]. For tooth-colored ceramic inlays in esthetic dentistry^ [7, 10], technical details about the application of different instruments for cavity preparation are clinically rele- vant because side effects, such as border defects and very irreg- * Ella A. Naumova ular surfaces, especially in proximal box cavities [9]; cracks, ella.naumova@uni-wh.de especially in the enamel [1]; and iatrogenic damage to adjacent teeth [11–13], may occur. This mechanical damage may result Department of Biological and Material Sciences in Dentistry, School in possible biological complications, such as tooth sensitivity of Dentistry, Faculty of Health, Witten/Herdecke University, and bacterial leakage [7]. Different types of instrumental Alfred-Herrhausen-Strasse 44, 58455 Witten, Germany methods for dental cavity preparation are currently in use: Department of Prosthodontics, School of Dentistry, Faculty of conventional-rotating [9], laser [1, 14, 15], sonic [9], or ultra- Health, Witten/Herdecke University, Alfred-Herrhausen-Strasse 44, sonic preparation [16, 17]. Mechanical damage of the teeth is 58455 Witten, Germany Clin Oral Invest more likely to occur with the use of rotating instruments [9]. Ultrasonic instruments are widely used in dentistry because of better efficiency, visualization, operative convenience, precise cutting ability [17], and success in accessing difficult areas on the preparation margin [16]. Molar esthetic restoration is in demand [18]. Ceramic in- lays are indicated for tooth restoration in extended mod- cavities with a loss of proximal contacts [19]. The marginal quality of ceramic inlays, especially the quality of the proxi- mal margins, is very important for providing highly esthetic, long-lasting, plaque-resistant restorations [2, 20, 21]. The presence of surface irregularities in the inlay proximal area can increase plaque formation, gingival irritation, recurrent caries, abrasiveness, wear kinetics, staining, and tactile per- ception by the patient [20, 22–24]. Marginal quality is of clin- ical importance for the process of bacterial retention [22, 25]. Therefore, the possible influence of different types of dental restorations on microleakage and marginal adaptation should be demonstrated with the use of different methods for cavity preparation [1, 2]. However, only limited information is avail- able about the proximal margin quality of the ceramic inlays in molar teeth after mesio-occluso-distal cavity proximal box finishing with sonic and ultrasonic instruments after hydro- thermal loading (HTL) in vitro [9, 21]. The marginal quality of the ceramic inlay approximal area is of clinical importance because the ceramic inlay approximal Fig. 1 Set-up of the present study area is located in the interdental space, and tooth brushing in this area is restricted [16, 26]. The aim of this in vitro study is to evaluate the influence of Cavity preparation different alternative methods of shaping and finishing mod- cavity proximal boxes on the adaptation of ceramic inlays to For the realistic simulation of tooth preparation, a specially the tooth morphology and bonding quality. designed original lower jaw model was constructed for precise The null hypothesis for the present study was that three positioning and stable fixation of the experimental teeth different finishing methods of mod-cavities in human molars (Fig. 2). Initially, the roots of the experimental teeth were would not differ in their effects on the surface roughness and coated with condensation-K-Silikon (HLW Dental, border quality of the proximal boxes, microleakage, and mar- Wernberg-Köblitz, Germany). Then, the experimental teeth ginal gap of the ceramic inlays within the enamel. were placed in the U-profile (the row) of the lower jaw be- tween teeth 45 and 47 (Frasaco GmbH, Tettnang, Germany) and aligned along the occlusion. Then, teeth 45 and 47 were Materials and methods moved until the proximal contacts from both sides of the ex- perimental tooth were reached. Thereafter, the original lower Tooth collection jaw model with the experimental tooth was placed and fixed in the head model (Frasaco GmbH, Tettnang, Germany) with the Tooth collection was approved by the ethical committee of face mask P-6 GM (Frasaco GmbH, Tettnang, Germany) and Witten/Herdecke University (permission 116/2013). For this the opposing upper jaw ANKA-4 (Frasaco GmbH, Tettnang, study, a total of 60 extracted human molar teeth were collect- Germany). ed. They were caries-free, lacked dental calculus, and had All specimen preparations were performed by the same completed root growth, comparable sizes, and absolute integ- operator and calibrated prior to the study by one of the authors rity. Immediately after extraction, the teeth were stored in to avoid inter-examiner differences. 0.9% NaCl containing 0.1% thymol at room temperature For the preparation, the AG ceramics guidelines of Ahlers (maximum 1–3 months) until use. Tissue remnants on the et al. 2009 [27] for a ceramic inlay with a mod-cavity were teeth surface were removed with a universal scaler. The teeth followed. The following geometrical parameters for the mod- were randomly distributed into three groups (Fig. 1). cavity were kept: a diverging angle of approximately 6°, a Clin Oral Invest Fig. 2 The specially constructed original lower jaw model: a without the experimental teeth, b with the experimental teeth with the prepared mod-cavity for the full ceramic inlay minimal depth of the occlusal box in the deepest area of the Proximal box finishing was performed with three different fissure of approximately 1.5 mm, a minimal width of the isth- methods and instruments in the three groups. mus of approximately 1.5 mm, a cavity surface angle of ap- proximately 90°, and a planar occlusal and proximal cavity Proximal box finishing in group 1 floor. The cervical margin preparation was located in enamel with a maximum dimension of 1.5 mm above the enamel- Proximal box finishing in group 1 was performed with the red cementum junction. high-speed angle Synea Vision WK-99 LT handpiece (W & H The dimensions of the mod-cavities were maintained with Germany GmbH, Laufen, Germany) under 10–20% power the preparation instruments with defined conicity and laser (ratio 1:5, engine speed 4000–8.000 rpm, speed of the instru- depth markings and were finally controlled with the CP-15 ment 20,000–40,000 rpm) and the rotating red-ringed conical UNC periodontometer (Hu-Friedy Mfg. Co., LLC, diamond instrument 8847KR 314 016 (Komet, Lemgo, Tuttlingen, Germany). The transitions within the mod-cavity Germany) (grain size ca. 30–45 μm, conicity ca. 2°); the were rounded off, and the proximal contacts to the adjacent neighboring teeth were protected by steel-band matrices. tooth were completely separated. The mod-cavity preparation was performed in three steps: Proximal box finishing in group 2 (1) initial whole mod-cavity shaping in all groups (n =60), (2) mod-cavity proximal box finishing within every three groups Proximal box finishing in group 2 was performed with the (n = 20), and (3) rounding and smoothing all sharp edges in- SF1LM sonic handpiece (Komet, Lemgo, Germany) and with side of the mod-cavity in all groups (n = 60). Initial whole SFD7 000 1 (distal) and SFM7 000 1 (mesial) sonic tips cavity shaping for 60 teeth was performed in all groups using (Komet, Lemgo, Germany) (grain size ca. 60 μm, conicity the same method with the Synea Vision WK-99 LT handpiece ca. 8°) on power setting 3 for shaping (amplitude of the free (W & H Germany GmbH, Laufen, Germany) under ca. 80% axial oscillation: 180–200 μm) and on power setting 1 for power (ratio 1:5, engine speed 32,000 rpm, speed of the in- finishing (amplitude of the free axial oscillation: 100– strument 160,000 rpm) and diamond instruments. Then, a 140 μm). purely occlusal limited cavity along the main fissure was pro- duced with the 959KRD 314,018 non-ringed diamond conical grinder (Komet, Lemgo, Germany) (grain size ca. 100 μm, Proximal box finishing in group 3 laser marking at 2 and 4 mm, conicity ca. 2°). After this, the proximal box to the dissolution of the basal contact point was Proximal box finishing in group 3 was performed with the created with a 6847KRD 314 016 green ringed conical dia- ultrasonic Sirona Perioscan drive (Sirona Dental GmbH, mond grinder (Komet, Lemgo, Germany) (grain size ca. Wals, Austria), the ultrasound Periosonic handpiece (Sirona 125 μm, laser marking at 2 and 4 mm, conicity ca. 2°). This Dental GmbH, Wals, Austria), and the SFD7 000 1 (distal) was done with the protection of the adjacent tooth with steel- and SFM7 000 1 (mesial) sonic tips (Komet, Lemgo, band matrices, which were fixed with a wooden wedge. The Germany) (grain size ca. 60 μm, conicity ca. 8°) at 100% occlusal box was smoothed with the red-ringed conical dia- power (32 kHz oscillation frequency). mond instrument 8959KR 314 018 (Komet, Lemgo, Because the sonic tips on the tooth-facing surface are grain- Germany) (grain size ca. 30–45 μm, conicity ca. 2°). After less, the protection of adjacent teeth with the steel band in the initial whole mod-cavity shaping of five teeth, the used groups 2 and 3 was not necessary. instruments were replaced with new ones. This rule was also In all groups, all sharp edges present inside the cavity were applied to subsequent proximal box finishing within groups. rounded and smoothed with the 8862 314 010 red-ringed Clin Oral Invest diamond flame (Komet, Lemgo, Germany) (grain size ca. 30– Artificial aging of the ceramic inlays 45 μm). Immediately after cementation, the teeth (n =16 from every Inlay production group) were subjected to thermocycling in the Thermocycler THE1000 (SD Mechatronics, Feldkirchen-Westerham, The prepared teeth were imprinted with Impregum Penta H Germany) with 5000 cycles in water baths at 5 and 55 °C Duosoft and Impregum Garant L Duosoft (3M, Seefeld, (resistance time 30 s, dripping time 15 s) to simulate hydro- Germany) using a double mixing technique at room thermal stress for the subsequent microleakage and marginal temperature. gap examination. Then, the ceramic inlays were conventionally modeled, pressed, adjusted, and completed according to standard labo- Silver nitrate (AgNO ) penetration ratory procedures. After removal from the thermocycler, the teeth were rinsed Quality control of the ceramic inlays with distilled water and dried with a paper towel. The dry teeth were sealed with two layers of Pattex Mini Trio superglue Prior to cementing, two independent examiners visually (Henkel AG & Co. KGaA, Dusseldorf, Germany). The basal inspected the ceramic inlays under a magnifying glass (× proximal preparation margin and 0.5 mm circular remained 2.5). The entire restoration margin was explicitly controlled unsealed. After drying for 30 min, the teeth were immersed in in the mesial and distal proximal range. Only clinically accept- AgNO (56.62 g/1 L H O) for 6 h. Subsequently, the teeth 3 2 able inlays were added to the study. Clinically unacceptable were exposed to four illuminants of 100 W for 4 h. After inlays were newly manufactured and controlled again. exposure, AgNO was developed in liquid Periomat Intra de- veloper (Dürr Dental, Bietigheim-Bissingen, Germany). The Cementation of the ceramic inlays depth of silver precipitation was measured in the sections (Fig. 3). The basal surface of the ceramic inlay was etched for 20 s with ceramic etching gel that contained 5% hydrofluoric acid IPS Preparation of sections (Ivoclar Vivadent AG, Schaan, Liechtenstein), then rinsed for 20 s with the multifunctional syringe, dried and covered for All specimens were embedded in Technovit 9100 (Heraeus 60 s with the single-component adhesion primer Monobond Kulzer, Werheim, Germany). Then, the specimens were cut Plus (Ivoclar Vivadent AG, Schaan, Liechtenstein). Enamel in the middle of the sagittal plane through the ceramic inlay and dentine in the mod-cavity were etched for 30 and 15 s, with a Leica SP1600 Saw Microtome (Leica Biosystems respectively, with 37% phosphoric acid (Ivoclar Vivadent AG, GmbH, Wetzlar, Germany). Schaan, Liechtenstein), then rinsed for 30 s with the multi- functional syringe, dried and covered for 20 s with Universal Assessment of surface roughness of the proximal box floor Adhesive (Ivoclar Vivadent AG, Schaan, Liechtenstein). Adhesive was blown into a uniformly thin film and cured After preparation and before taking an impression, the surface for 10 s with the Satelec Mini Led SP dental curing light roughness of each proximal box floor was determined with an (Acteon Germany GmbH, Mettmann, Germany) at a distance Alicona Infinite Focus optical measuring system and Alicona of approximately 1 mm. Then, the basal surface of the inlay IFM 3.2 computer software (Alicona Imaging GmbH, Raaba/ was covered with the dual-curing luting composite Variolink Graz, Austria). In three areas of each proximal box floor, five esthetic DC (Ivoclar Vivadent AG, Schaan, Liechtenstein) and measurements were taken, and the mean roughness (Ra) was inserted into the mod-cavity with uniform pressure. The ex- determined. cess composite was removed with a foam pellet. Then, the ceramic inlay was kept in the correct position with a Assessment of marginal gap Heidemann-spatula under gentle pressure. The inlay was cured for 10 s with the Satelec Mini Led SP dental curing light The measurement of the marginal gap as defined by (Acteon Germany GmbH, Mettmann, Germany) from the Holmes et al. (1989) of the individual specimens was car- occlusal-mesial and occlusal-distal sides at an angle of ap- ried out with a scanning electron microscope (Sigma VP, proximately 45° to the occlusal plane, at a distance of approx- Carl Zeiss AG, Oberkochen, Germany) in low vacuum imately 1 mm from the tooth. To avoid an oxygen-inhibiting mode (VP) at 20 Pa at 20 kV and 500-fold magnification. layer, the gap between the inlay and the tooth-hard substance The marginal gap was measured with the Bpoint-to-point- before polymerization was covered with a glyceringel liquid measure^ function of the SmartSEM computer software strip (Ivoclar Vivadent AG, Schaan, Liechtenstein). (Carl Zeiss AG, Oberkochen, Germany). The mesial and Clin Oral Invest Fig. 3 Measurement of the microleakage. The depth of the silver precipitation is marked with an empty arrow, luting composite with a full arrow distal proximal areas of inlays were investigated with re- 75) with the Bpoint-to-point-measure^ function of the spect to the marginal gap and the absolute marginal dis- SmartSEM computer software (Carl Zeiss AG, Oberkochen, crepancy (aMOP gap) [28]. Since the inlay is suitably Germany). contoured, the marginal gap and the absolute marginal dis- crepancy (MOP gap) are equal—in this case, 98.37 μm (Fig. 4). Statistics Prior to statistical calculations, the normality of the data Assessment of microleakage was checked using the Kolmogorov-Smirnov test. As the data were not normally distributed, non-parametric tests For the measurement of AgNO penetration, photographs of were applied. For the comparison of group differences, the cut samples were taken with a Leica Wild 3ZM stereomi- the Mann-Whitney U test was applied. As multiple com- croscope (Leica Camera AG, Wetzlar, Germany). For the parisons were calculated, the Bonferroni correction of the computer-assisted measurement of AgNO penetration, the alpha error resulted in a p value of 0.016. Correlations were images were examined with AutoCAD 2011 computer soft- calculated with the non-parametric Spearman-Rho test. ware (Autodesk GmbH, Munich, Germany). The distance be- The Statistical Package for Social Sciences program tween the extreme point of the preparation edge and the cen- (SPSS, IBM, Amronk, NJ, USA) Vers. 23 was used. tral point of AgNO penetration was measured. These mea- surements were repeated by an additional independent examiner. Results Assessment of the ceramic inlay proximal box margin quality Comparison of the proximal box floor surface For the evaluation of the ceramic inlay proximal box margin roughness after using different proximal box quality, the tooth crowns with the ceramic inlays (n = 4 from finishing methods every group) were cut into two halves in the bucco-oral direction with a diamond disk, sputtered from the proximal Microscopically qualitative differences in the surface tex- side with gold-palladium and investigated with a scanning ture were found after preparation with the different instru- electron microscope (Sigma VP, Carl Zeiss AG, mental methods (Fig. 5). A significant increase in the sur- Oberkochen, Germany) in high vacuum mode at 20-kVaccel- face roughness of the proximal box floor was found in eration voltage and the secondary electron detector (SE) at 75- samples that underwent rotating preparation and sonic fold magnification. Then, the quality of proximal box margin preparation and ultrasonic preparation (p < 0.001). No sig- preparation was visually defined, as seen in Table 1 [9, 29]. nificant differences were found in the surface roughness of Finally, the length of the ceramic inlay proximal box margin samples subjected to sonic and ultrasonic preparation (p = sections with the different qualities was measured via SEM (× 0.016) (Fig. 6). Clin Oral Invest Fig. 4 Measurements of the marginal gap (MOP) and absolute marginal gap (aMOP) Comparison of the ceramic inlay proximal Quality of the ceramic inlay proximal margin microleakage after using the different proximal box after using different proximal box finishing methods finishing methods The distribution of the defined qualities at the ceramic inlay No statistically significant differences were found between proximal margin was similar in all three groups. Qualities A1 any of the groups regarding the ceramic inlay proximal and A2 were most common, and qualities A3 and B were the microleakage (Fig. 7). least common (Fig. 10). Comparison of the ceramic inlay proximal marginal Discussion gap after using different proximal box finishing methods The strategies for prolonging the clinical lifetime of esthetic tooth-colored ceramic restorations are timely [21]. A simple, No statistically significant differences were found between convenient, and safe way to achieve adjacent tooth prepara- any of the groups regarding proximal marginal gap tion (finishing) is a major point of interest for clinicians. (Fig. 8). Different instruments must be used to stabilize and improve the adhesive interface and the overall dental restoration quality [7]. However, their effects on the dentin and enamel surfaces Comparison of the ceramic inlay proximal absolute are contradictory [16]. It is known that rotating instruments, marginal gaps after using different proximal box compared to sonic and ultrasonic instruments, result in more finishing methods mod-cavity proximal box border defects, very irregular sur- faces [9], and iatrogenic damage to adjacent teeth. Clinically, No statistically significant differences were found between changes in the marginal quality of ceramic inlays are any of the groups regarding absolute marginal gap (Fig. 9). Table 1 Definition of the proximal box margin quality Quality range Definition Correlation between microleakage, marginal, and absolute marginal gaps Clinically acceptable Quality A1 Margin with regular even course Quality A2 Margin with waved course No statistically significant correlations were found between Quality A3 Margin irregular, microleakage and marginal gap (r = − 0.103; p =0.704), with zig zag course microleakage and absolute marginal gap (r = − 0.024; p = Clinically Quality B Margin cannot be defined 0.931), or microleakage and roughness (r = − 0.103; p = unacceptable 0.704) in all three groups. Clin Oral Invest Fig. 5 The different patterns of proximal box floor surface roughness after the use of the proximal box finishing methods with three different instruments: a rotating, b sonic, and c ultrasonic important because aging (wear) may influence bacterial restauration [30]. Differences in the quality of dentin surface plaque retention. and the bond strength after preparation with different kinds of Thus, the aim of this in vitro study was to evaluate the ultrasonic preparation tips have also been reported [16]. marginal quality of the ceramic inlays in human molars after The data of this study also clearly demonstrated that the use of three different instrumental finishing methods. microleakage, marginal, absolute marginal gaps after HTL Rotating, sonic, and ultrasonic instruments were used for and proximal marginal quality were not significantly different mod-cavity proximal box finishing in vitro, and their effects (p > 0.05) among the three different instrumental finishing on the proximal box floor surface roughness, percentage of methods. No correlations between microleakage, marginal continuous margin quality (% of total proximal margin and absolute marginal gaps or between microleakage and sur- length), microleakage, marginal and absolute marginal gaps face roughness were found. This is in accordance with the after hydrothermal loading (HTL) were assessed. The samples results of Ellis et al. (2012) that the use of ultrasonic instru- were analyzed via scanning electron microscopy (SEM) and ments for dentin preparation resulted in bond strengths that surface roughness analysis. were comparable to those obtained with the use of diamond The data in this study showed a significant increase (p < burs [16, 28]. Zaruba et al. (2014) concluded that the prepa- 0.001) in the surface roughness of the proximal box floor after ration design of mod-cavities for ceramic inlays does not in- finishing with the sonic and ultrasonic instruments compared fluence marginal adaption [31]. Hopp et al. (2013) summa- to finishing with the rotating instrument. The quality of the rized in their review that the preparation design consider- dentin surface has influenced the bond strength of the ations, fabrication methods, and material choice of ceramic Fig. 6 Boxplot of the data distribution of the surface roughness measurements after different preparation methods. The pound symbol indicates the comparisons among data Clin Oral Invest Fig. 7 Boxplot of the data distribution of the ceramic inlay proximal microleakage measurements. The pound symbol indicates the comparisons among data inlays do not influence tooth wear [32]. During the analysis of evaluation was not compared with the evaluation of another the finishing protocols, some peculiarities for different instru- investigator. mental methods were determined. The finishing procedure Proximal box finishing of mod-cavities in human molars with the sonic and ultrasonic instruments was more simple with SI or USI resulted in a higher value of surface roughness and convenient for the operator because finishing was per- than with RI as a result of the coarser grid of the SI and USI. formed without the help of the steel-band matrices and was The type of finishing method did not significantly influence safe for the adjustment of teeth because of the grainless tips. microleakage, marginal or absolute marginal gaps, or proxi- The limitations of this study are that artificial aging was mal box marginal quality. performed only with HTL, the qualitative lower proximal The data showed that SI and USI increased the surface marginal gap was only evaluated by one investigator, and this roughness of the proximal boxes and did not increase Fig. 8 Boxplot of the data distribution of the ceramic inlay proximal marginal gap measurements after using different proximal box finishing methods. The pound symbol indicates the comparisons among data Clin Oral Invest Fig. 9 Boxplot graphics of the data distribution of the ceramic inlay proximal absolute marginal gap measurements after using different proximal box finishing methods. The pound symbol indicates the comparisons among data microleakage or marginal discrepancy of the ceramic inlays. will not differ in their influence on the surface roughness and Therefore, the inlay internal fit, and the proximal marginal border quality of the proximal boxes, microleakage, and mar- quality after the proximal box finishing with SI and USI ginal gap of the ceramic inlays within enamel, was partly corresponded to the proximal marginal quality after finishing confirmed. with RI. For the proximal box mod-cavity finishing, the use of SI The null hypothesis for the present study, that three differ- and USI could be an alternative instrumental method to con- ent finishing methods of the mod-cavities in human molars ventional RI methods, with a lower risk of iatrogenic damage Fig. 10 Different ceramic inlay approximal margin qualities after the use of three different finishing methods for the mod-cavity proximal boxes Clin Oral Invest of the adjacent teeth. Clinical research is needed to confirm References these findings. 1. Bader C, Krejci I (2006) Indications and limitations of Er:YAG laser applications in dentistry. Am J Dent 19(3):178–186 2. Stappert CF, Ozden U, Att W, Gerds T, Strub JR (2007) Marginal Conclusion accuracy of press-ceramic veneers influenced by preparation design and fatigue. Am J Dent 20(6):380–384 Ceramic inlays inserted in mod-cavities with proximal 3. 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Marginal quality of ceramic inlays after three different instrumental cavity preparation methods of the proximal boxes

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Dentistry; Dentistry
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1432-6981
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10.1007/s00784-018-2492-0
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Abstract

Objectives The marginal quality of ceramic inlays was evaluated after the use of three different instrumental finishing methods in mesio-occluso-distal (mod) cavity boxes in vitro after hydrothermal loading (HTL). Materials and methods Caries-free human molars were divided into three groups. Mod-cavities were conventionally prepared. Box finishing was performed in every group with rotating (RI), sonic (SI), or ultrasonic (USI) instruments. Surface roughness was examined. Twelve mod-cavities remained untreated. Continuous margin quality was evaluated with scanning electron microscopy (SEM). Ceramic inlays were cemented into cavities. After HTL microleakage, marginal and absolute marginal gaps were examined. All data were analyzed statistically. Results Significant differences were found, between cavity surface roughness of RI and SI groups, the RI and USI groups, but not between microleakage, marginal, absolute marginal gaps after HTL and in proximal marginal quality. No correlations between microleakage and marginal gaps nor between microleakage and surface roughness were found. Conclusion Mod-cavity proximal box finishing with SI or USI resulted in a higher surface roughness than the use of RI. The type of the finishing method did not influence the marginal quality of ceramic inlays. For the mod-cavity finishing, the use of SI and USI could be an alternative instrumental method to conventional RI methods with a lower risk of iatrogenic damage of the adjacent teeth. Clinical relevance This study allows the practitioner to better determine the proper indications and limitations of the sonic and ultrasonic instruments for mod-cavity proximal box finishing. . . . . . . Keywords Surface roughness Microleakage Marginal gap Margin quality Ceramic inlays Finishing methods Hydrothermal wear Introduction dentistry, the long-term success is an actual problem [7]. Accordingly, information and discussion about the applica- Qualitative cavity preparation without discomfort is very im- tions and effects of the different instrumental methods of cav- portant in restorative dentistry [1]. The restoration geometry, ity preparation [1, 9], technical requirements, and the effective design considerations, preparation methods, and loading con- preparation of dental tissues [7] are in demand. ditions are key factors for the long-term success of dental According to the concept of Bminimally hazardous restorations [2–8]. For tooth-colored ceramic inlays in esthetic dentistry^ [7, 10], technical details about the application of different instruments for cavity preparation are clinically rele- vant because side effects, such as border defects and very irreg- * Ella A. Naumova ular surfaces, especially in proximal box cavities [9]; cracks, ella.naumova@uni-wh.de especially in the enamel [1]; and iatrogenic damage to adjacent teeth [11–13], may occur. This mechanical damage may result Department of Biological and Material Sciences in Dentistry, School in possible biological complications, such as tooth sensitivity of Dentistry, Faculty of Health, Witten/Herdecke University, and bacterial leakage [7]. Different types of instrumental Alfred-Herrhausen-Strasse 44, 58455 Witten, Germany methods for dental cavity preparation are currently in use: Department of Prosthodontics, School of Dentistry, Faculty of conventional-rotating [9], laser [1, 14, 15], sonic [9], or ultra- Health, Witten/Herdecke University, Alfred-Herrhausen-Strasse 44, sonic preparation [16, 17]. Mechanical damage of the teeth is 58455 Witten, Germany Clin Oral Invest more likely to occur with the use of rotating instruments [9]. Ultrasonic instruments are widely used in dentistry because of better efficiency, visualization, operative convenience, precise cutting ability [17], and success in accessing difficult areas on the preparation margin [16]. Molar esthetic restoration is in demand [18]. Ceramic in- lays are indicated for tooth restoration in extended mod- cavities with a loss of proximal contacts [19]. The marginal quality of ceramic inlays, especially the quality of the proxi- mal margins, is very important for providing highly esthetic, long-lasting, plaque-resistant restorations [2, 20, 21]. The presence of surface irregularities in the inlay proximal area can increase plaque formation, gingival irritation, recurrent caries, abrasiveness, wear kinetics, staining, and tactile per- ception by the patient [20, 22–24]. Marginal quality is of clin- ical importance for the process of bacterial retention [22, 25]. Therefore, the possible influence of different types of dental restorations on microleakage and marginal adaptation should be demonstrated with the use of different methods for cavity preparation [1, 2]. However, only limited information is avail- able about the proximal margin quality of the ceramic inlays in molar teeth after mesio-occluso-distal cavity proximal box finishing with sonic and ultrasonic instruments after hydro- thermal loading (HTL) in vitro [9, 21]. The marginal quality of the ceramic inlay approximal area is of clinical importance because the ceramic inlay approximal Fig. 1 Set-up of the present study area is located in the interdental space, and tooth brushing in this area is restricted [16, 26]. The aim of this in vitro study is to evaluate the influence of Cavity preparation different alternative methods of shaping and finishing mod- cavity proximal boxes on the adaptation of ceramic inlays to For the realistic simulation of tooth preparation, a specially the tooth morphology and bonding quality. designed original lower jaw model was constructed for precise The null hypothesis for the present study was that three positioning and stable fixation of the experimental teeth different finishing methods of mod-cavities in human molars (Fig. 2). Initially, the roots of the experimental teeth were would not differ in their effects on the surface roughness and coated with condensation-K-Silikon (HLW Dental, border quality of the proximal boxes, microleakage, and mar- Wernberg-Köblitz, Germany). Then, the experimental teeth ginal gap of the ceramic inlays within the enamel. were placed in the U-profile (the row) of the lower jaw be- tween teeth 45 and 47 (Frasaco GmbH, Tettnang, Germany) and aligned along the occlusion. Then, teeth 45 and 47 were Materials and methods moved until the proximal contacts from both sides of the ex- perimental tooth were reached. Thereafter, the original lower Tooth collection jaw model with the experimental tooth was placed and fixed in the head model (Frasaco GmbH, Tettnang, Germany) with the Tooth collection was approved by the ethical committee of face mask P-6 GM (Frasaco GmbH, Tettnang, Germany) and Witten/Herdecke University (permission 116/2013). For this the opposing upper jaw ANKA-4 (Frasaco GmbH, Tettnang, study, a total of 60 extracted human molar teeth were collect- Germany). ed. They were caries-free, lacked dental calculus, and had All specimen preparations were performed by the same completed root growth, comparable sizes, and absolute integ- operator and calibrated prior to the study by one of the authors rity. Immediately after extraction, the teeth were stored in to avoid inter-examiner differences. 0.9% NaCl containing 0.1% thymol at room temperature For the preparation, the AG ceramics guidelines of Ahlers (maximum 1–3 months) until use. Tissue remnants on the et al. 2009 [27] for a ceramic inlay with a mod-cavity were teeth surface were removed with a universal scaler. The teeth followed. The following geometrical parameters for the mod- were randomly distributed into three groups (Fig. 1). cavity were kept: a diverging angle of approximately 6°, a Clin Oral Invest Fig. 2 The specially constructed original lower jaw model: a without the experimental teeth, b with the experimental teeth with the prepared mod-cavity for the full ceramic inlay minimal depth of the occlusal box in the deepest area of the Proximal box finishing was performed with three different fissure of approximately 1.5 mm, a minimal width of the isth- methods and instruments in the three groups. mus of approximately 1.5 mm, a cavity surface angle of ap- proximately 90°, and a planar occlusal and proximal cavity Proximal box finishing in group 1 floor. The cervical margin preparation was located in enamel with a maximum dimension of 1.5 mm above the enamel- Proximal box finishing in group 1 was performed with the red cementum junction. high-speed angle Synea Vision WK-99 LT handpiece (W & H The dimensions of the mod-cavities were maintained with Germany GmbH, Laufen, Germany) under 10–20% power the preparation instruments with defined conicity and laser (ratio 1:5, engine speed 4000–8.000 rpm, speed of the instru- depth markings and were finally controlled with the CP-15 ment 20,000–40,000 rpm) and the rotating red-ringed conical UNC periodontometer (Hu-Friedy Mfg. Co., LLC, diamond instrument 8847KR 314 016 (Komet, Lemgo, Tuttlingen, Germany). The transitions within the mod-cavity Germany) (grain size ca. 30–45 μm, conicity ca. 2°); the were rounded off, and the proximal contacts to the adjacent neighboring teeth were protected by steel-band matrices. tooth were completely separated. The mod-cavity preparation was performed in three steps: Proximal box finishing in group 2 (1) initial whole mod-cavity shaping in all groups (n =60), (2) mod-cavity proximal box finishing within every three groups Proximal box finishing in group 2 was performed with the (n = 20), and (3) rounding and smoothing all sharp edges in- SF1LM sonic handpiece (Komet, Lemgo, Germany) and with side of the mod-cavity in all groups (n = 60). Initial whole SFD7 000 1 (distal) and SFM7 000 1 (mesial) sonic tips cavity shaping for 60 teeth was performed in all groups using (Komet, Lemgo, Germany) (grain size ca. 60 μm, conicity the same method with the Synea Vision WK-99 LT handpiece ca. 8°) on power setting 3 for shaping (amplitude of the free (W & H Germany GmbH, Laufen, Germany) under ca. 80% axial oscillation: 180–200 μm) and on power setting 1 for power (ratio 1:5, engine speed 32,000 rpm, speed of the in- finishing (amplitude of the free axial oscillation: 100– strument 160,000 rpm) and diamond instruments. Then, a 140 μm). purely occlusal limited cavity along the main fissure was pro- duced with the 959KRD 314,018 non-ringed diamond conical grinder (Komet, Lemgo, Germany) (grain size ca. 100 μm, Proximal box finishing in group 3 laser marking at 2 and 4 mm, conicity ca. 2°). After this, the proximal box to the dissolution of the basal contact point was Proximal box finishing in group 3 was performed with the created with a 6847KRD 314 016 green ringed conical dia- ultrasonic Sirona Perioscan drive (Sirona Dental GmbH, mond grinder (Komet, Lemgo, Germany) (grain size ca. Wals, Austria), the ultrasound Periosonic handpiece (Sirona 125 μm, laser marking at 2 and 4 mm, conicity ca. 2°). This Dental GmbH, Wals, Austria), and the SFD7 000 1 (distal) was done with the protection of the adjacent tooth with steel- and SFM7 000 1 (mesial) sonic tips (Komet, Lemgo, band matrices, which were fixed with a wooden wedge. The Germany) (grain size ca. 60 μm, conicity ca. 8°) at 100% occlusal box was smoothed with the red-ringed conical dia- power (32 kHz oscillation frequency). mond instrument 8959KR 314 018 (Komet, Lemgo, Because the sonic tips on the tooth-facing surface are grain- Germany) (grain size ca. 30–45 μm, conicity ca. 2°). After less, the protection of adjacent teeth with the steel band in the initial whole mod-cavity shaping of five teeth, the used groups 2 and 3 was not necessary. instruments were replaced with new ones. This rule was also In all groups, all sharp edges present inside the cavity were applied to subsequent proximal box finishing within groups. rounded and smoothed with the 8862 314 010 red-ringed Clin Oral Invest diamond flame (Komet, Lemgo, Germany) (grain size ca. 30– Artificial aging of the ceramic inlays 45 μm). Immediately after cementation, the teeth (n =16 from every Inlay production group) were subjected to thermocycling in the Thermocycler THE1000 (SD Mechatronics, Feldkirchen-Westerham, The prepared teeth were imprinted with Impregum Penta H Germany) with 5000 cycles in water baths at 5 and 55 °C Duosoft and Impregum Garant L Duosoft (3M, Seefeld, (resistance time 30 s, dripping time 15 s) to simulate hydro- Germany) using a double mixing technique at room thermal stress for the subsequent microleakage and marginal temperature. gap examination. Then, the ceramic inlays were conventionally modeled, pressed, adjusted, and completed according to standard labo- Silver nitrate (AgNO ) penetration ratory procedures. After removal from the thermocycler, the teeth were rinsed Quality control of the ceramic inlays with distilled water and dried with a paper towel. The dry teeth were sealed with two layers of Pattex Mini Trio superglue Prior to cementing, two independent examiners visually (Henkel AG & Co. KGaA, Dusseldorf, Germany). The basal inspected the ceramic inlays under a magnifying glass (× proximal preparation margin and 0.5 mm circular remained 2.5). The entire restoration margin was explicitly controlled unsealed. After drying for 30 min, the teeth were immersed in in the mesial and distal proximal range. Only clinically accept- AgNO (56.62 g/1 L H O) for 6 h. Subsequently, the teeth 3 2 able inlays were added to the study. Clinically unacceptable were exposed to four illuminants of 100 W for 4 h. After inlays were newly manufactured and controlled again. exposure, AgNO was developed in liquid Periomat Intra de- veloper (Dürr Dental, Bietigheim-Bissingen, Germany). The Cementation of the ceramic inlays depth of silver precipitation was measured in the sections (Fig. 3). The basal surface of the ceramic inlay was etched for 20 s with ceramic etching gel that contained 5% hydrofluoric acid IPS Preparation of sections (Ivoclar Vivadent AG, Schaan, Liechtenstein), then rinsed for 20 s with the multifunctional syringe, dried and covered for All specimens were embedded in Technovit 9100 (Heraeus 60 s with the single-component adhesion primer Monobond Kulzer, Werheim, Germany). Then, the specimens were cut Plus (Ivoclar Vivadent AG, Schaan, Liechtenstein). Enamel in the middle of the sagittal plane through the ceramic inlay and dentine in the mod-cavity were etched for 30 and 15 s, with a Leica SP1600 Saw Microtome (Leica Biosystems respectively, with 37% phosphoric acid (Ivoclar Vivadent AG, GmbH, Wetzlar, Germany). Schaan, Liechtenstein), then rinsed for 30 s with the multi- functional syringe, dried and covered for 20 s with Universal Assessment of surface roughness of the proximal box floor Adhesive (Ivoclar Vivadent AG, Schaan, Liechtenstein). Adhesive was blown into a uniformly thin film and cured After preparation and before taking an impression, the surface for 10 s with the Satelec Mini Led SP dental curing light roughness of each proximal box floor was determined with an (Acteon Germany GmbH, Mettmann, Germany) at a distance Alicona Infinite Focus optical measuring system and Alicona of approximately 1 mm. Then, the basal surface of the inlay IFM 3.2 computer software (Alicona Imaging GmbH, Raaba/ was covered with the dual-curing luting composite Variolink Graz, Austria). In three areas of each proximal box floor, five esthetic DC (Ivoclar Vivadent AG, Schaan, Liechtenstein) and measurements were taken, and the mean roughness (Ra) was inserted into the mod-cavity with uniform pressure. The ex- determined. cess composite was removed with a foam pellet. Then, the ceramic inlay was kept in the correct position with a Assessment of marginal gap Heidemann-spatula under gentle pressure. The inlay was cured for 10 s with the Satelec Mini Led SP dental curing light The measurement of the marginal gap as defined by (Acteon Germany GmbH, Mettmann, Germany) from the Holmes et al. (1989) of the individual specimens was car- occlusal-mesial and occlusal-distal sides at an angle of ap- ried out with a scanning electron microscope (Sigma VP, proximately 45° to the occlusal plane, at a distance of approx- Carl Zeiss AG, Oberkochen, Germany) in low vacuum imately 1 mm from the tooth. To avoid an oxygen-inhibiting mode (VP) at 20 Pa at 20 kV and 500-fold magnification. layer, the gap between the inlay and the tooth-hard substance The marginal gap was measured with the Bpoint-to-point- before polymerization was covered with a glyceringel liquid measure^ function of the SmartSEM computer software strip (Ivoclar Vivadent AG, Schaan, Liechtenstein). (Carl Zeiss AG, Oberkochen, Germany). The mesial and Clin Oral Invest Fig. 3 Measurement of the microleakage. The depth of the silver precipitation is marked with an empty arrow, luting composite with a full arrow distal proximal areas of inlays were investigated with re- 75) with the Bpoint-to-point-measure^ function of the spect to the marginal gap and the absolute marginal dis- SmartSEM computer software (Carl Zeiss AG, Oberkochen, crepancy (aMOP gap) [28]. Since the inlay is suitably Germany). contoured, the marginal gap and the absolute marginal dis- crepancy (MOP gap) are equal—in this case, 98.37 μm (Fig. 4). Statistics Prior to statistical calculations, the normality of the data Assessment of microleakage was checked using the Kolmogorov-Smirnov test. As the data were not normally distributed, non-parametric tests For the measurement of AgNO penetration, photographs of were applied. For the comparison of group differences, the cut samples were taken with a Leica Wild 3ZM stereomi- the Mann-Whitney U test was applied. As multiple com- croscope (Leica Camera AG, Wetzlar, Germany). For the parisons were calculated, the Bonferroni correction of the computer-assisted measurement of AgNO penetration, the alpha error resulted in a p value of 0.016. Correlations were images were examined with AutoCAD 2011 computer soft- calculated with the non-parametric Spearman-Rho test. ware (Autodesk GmbH, Munich, Germany). The distance be- The Statistical Package for Social Sciences program tween the extreme point of the preparation edge and the cen- (SPSS, IBM, Amronk, NJ, USA) Vers. 23 was used. tral point of AgNO penetration was measured. These mea- surements were repeated by an additional independent examiner. Results Assessment of the ceramic inlay proximal box margin quality Comparison of the proximal box floor surface For the evaluation of the ceramic inlay proximal box margin roughness after using different proximal box quality, the tooth crowns with the ceramic inlays (n = 4 from finishing methods every group) were cut into two halves in the bucco-oral direction with a diamond disk, sputtered from the proximal Microscopically qualitative differences in the surface tex- side with gold-palladium and investigated with a scanning ture were found after preparation with the different instru- electron microscope (Sigma VP, Carl Zeiss AG, mental methods (Fig. 5). A significant increase in the sur- Oberkochen, Germany) in high vacuum mode at 20-kVaccel- face roughness of the proximal box floor was found in eration voltage and the secondary electron detector (SE) at 75- samples that underwent rotating preparation and sonic fold magnification. Then, the quality of proximal box margin preparation and ultrasonic preparation (p < 0.001). No sig- preparation was visually defined, as seen in Table 1 [9, 29]. nificant differences were found in the surface roughness of Finally, the length of the ceramic inlay proximal box margin samples subjected to sonic and ultrasonic preparation (p = sections with the different qualities was measured via SEM (× 0.016) (Fig. 6). Clin Oral Invest Fig. 4 Measurements of the marginal gap (MOP) and absolute marginal gap (aMOP) Comparison of the ceramic inlay proximal Quality of the ceramic inlay proximal margin microleakage after using the different proximal box after using different proximal box finishing methods finishing methods The distribution of the defined qualities at the ceramic inlay No statistically significant differences were found between proximal margin was similar in all three groups. Qualities A1 any of the groups regarding the ceramic inlay proximal and A2 were most common, and qualities A3 and B were the microleakage (Fig. 7). least common (Fig. 10). Comparison of the ceramic inlay proximal marginal Discussion gap after using different proximal box finishing methods The strategies for prolonging the clinical lifetime of esthetic tooth-colored ceramic restorations are timely [21]. A simple, No statistically significant differences were found between convenient, and safe way to achieve adjacent tooth prepara- any of the groups regarding proximal marginal gap tion (finishing) is a major point of interest for clinicians. (Fig. 8). Different instruments must be used to stabilize and improve the adhesive interface and the overall dental restoration quality [7]. However, their effects on the dentin and enamel surfaces Comparison of the ceramic inlay proximal absolute are contradictory [16]. It is known that rotating instruments, marginal gaps after using different proximal box compared to sonic and ultrasonic instruments, result in more finishing methods mod-cavity proximal box border defects, very irregular sur- faces [9], and iatrogenic damage to adjacent teeth. Clinically, No statistically significant differences were found between changes in the marginal quality of ceramic inlays are any of the groups regarding absolute marginal gap (Fig. 9). Table 1 Definition of the proximal box margin quality Quality range Definition Correlation between microleakage, marginal, and absolute marginal gaps Clinically acceptable Quality A1 Margin with regular even course Quality A2 Margin with waved course No statistically significant correlations were found between Quality A3 Margin irregular, microleakage and marginal gap (r = − 0.103; p =0.704), with zig zag course microleakage and absolute marginal gap (r = − 0.024; p = Clinically Quality B Margin cannot be defined 0.931), or microleakage and roughness (r = − 0.103; p = unacceptable 0.704) in all three groups. Clin Oral Invest Fig. 5 The different patterns of proximal box floor surface roughness after the use of the proximal box finishing methods with three different instruments: a rotating, b sonic, and c ultrasonic important because aging (wear) may influence bacterial restauration [30]. Differences in the quality of dentin surface plaque retention. and the bond strength after preparation with different kinds of Thus, the aim of this in vitro study was to evaluate the ultrasonic preparation tips have also been reported [16]. marginal quality of the ceramic inlays in human molars after The data of this study also clearly demonstrated that the use of three different instrumental finishing methods. microleakage, marginal, absolute marginal gaps after HTL Rotating, sonic, and ultrasonic instruments were used for and proximal marginal quality were not significantly different mod-cavity proximal box finishing in vitro, and their effects (p > 0.05) among the three different instrumental finishing on the proximal box floor surface roughness, percentage of methods. No correlations between microleakage, marginal continuous margin quality (% of total proximal margin and absolute marginal gaps or between microleakage and sur- length), microleakage, marginal and absolute marginal gaps face roughness were found. This is in accordance with the after hydrothermal loading (HTL) were assessed. The samples results of Ellis et al. (2012) that the use of ultrasonic instru- were analyzed via scanning electron microscopy (SEM) and ments for dentin preparation resulted in bond strengths that surface roughness analysis. were comparable to those obtained with the use of diamond The data in this study showed a significant increase (p < burs [16, 28]. Zaruba et al. (2014) concluded that the prepa- 0.001) in the surface roughness of the proximal box floor after ration design of mod-cavities for ceramic inlays does not in- finishing with the sonic and ultrasonic instruments compared fluence marginal adaption [31]. Hopp et al. (2013) summa- to finishing with the rotating instrument. The quality of the rized in their review that the preparation design consider- dentin surface has influenced the bond strength of the ations, fabrication methods, and material choice of ceramic Fig. 6 Boxplot of the data distribution of the surface roughness measurements after different preparation methods. The pound symbol indicates the comparisons among data Clin Oral Invest Fig. 7 Boxplot of the data distribution of the ceramic inlay proximal microleakage measurements. The pound symbol indicates the comparisons among data inlays do not influence tooth wear [32]. During the analysis of evaluation was not compared with the evaluation of another the finishing protocols, some peculiarities for different instru- investigator. mental methods were determined. The finishing procedure Proximal box finishing of mod-cavities in human molars with the sonic and ultrasonic instruments was more simple with SI or USI resulted in a higher value of surface roughness and convenient for the operator because finishing was per- than with RI as a result of the coarser grid of the SI and USI. formed without the help of the steel-band matrices and was The type of finishing method did not significantly influence safe for the adjustment of teeth because of the grainless tips. microleakage, marginal or absolute marginal gaps, or proxi- The limitations of this study are that artificial aging was mal box marginal quality. performed only with HTL, the qualitative lower proximal The data showed that SI and USI increased the surface marginal gap was only evaluated by one investigator, and this roughness of the proximal boxes and did not increase Fig. 8 Boxplot of the data distribution of the ceramic inlay proximal marginal gap measurements after using different proximal box finishing methods. The pound symbol indicates the comparisons among data Clin Oral Invest Fig. 9 Boxplot graphics of the data distribution of the ceramic inlay proximal absolute marginal gap measurements after using different proximal box finishing methods. The pound symbol indicates the comparisons among data microleakage or marginal discrepancy of the ceramic inlays. will not differ in their influence on the surface roughness and Therefore, the inlay internal fit, and the proximal marginal border quality of the proximal boxes, microleakage, and mar- quality after the proximal box finishing with SI and USI ginal gap of the ceramic inlays within enamel, was partly corresponded to the proximal marginal quality after finishing confirmed. with RI. 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Schweiz Monatsschr Funding The materials for this study were provided by Ivoclar Vivadent Zahnmed 105(10):1259–1264 AG, Schaan, Liechtenstein and Komet Dental, Lemgo, Germany. 12. Opdam NJ, Roeters JJ, van Berghem E, Eijsvogels E, Bronkhorst E (2002) Microleakage and damage to adjacent teeth when finishing Compliance with ethical standards class II adhesive preparations using either a sonic device or bur. Am J Dent 15(5):317–320 13. Lenters M, van Amerongen WE, Mandari GJ (2006) Iatrogenic Conflict of interests Ella A. Naumova declares that she has no conflict damage to the adjacent surfaces of primary molars, in three different of interest. ways of cavity preparation. Eur Arch Paediatr Dent 7(1):6–10 Fabian Schiml declares that he has no conflict of interest. Wolfgang. H. Arnold declares that he has no conflict of interest. 14. De Moor RJ, Delme KI (2009) Laser-assisted cavity preparation Andree Piwowarczyk declares that he has no conflict of interest. and adhesion to erbium-lased tooth structure: part 1. Laser- assisted cavity preparation. J Adhes Dent 11(6):427–438 15. De Moor RJ, Delme KI (2010) Laser-assisted cavity preparation Ethical approval This article does not contain any studies with human and adhesion to erbium-lased tooth structure: part 2. Present-day participants or animals performed by any of the authors. All procedures adhesion to erbium-lased tooth structure in permanent teeth. J performed in studies involving human participants were in accordance Adhes Dent 12(2):91–102 with the ethical standards of the institutional and/or national research 16. 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Mehl A, Kunzelmann KH, Folwaczny M, Hickel R (2004) distribution, and reproduction in any medium, provided you give appro- Stabilization effects of CAD/CAM ceramic restorations in extend- priate credit to the original author(s) and the source, provide a link to the ed MOD cavities. J Adhes Dent 6(3):239–245 Creative Commons license, and indicate if changes were made. Clin Oral Invest 20. LeSage B (2011) Finishing and polishing criteria for minimally 27. Ahlers MO, Mörig G, Blunck U, Hajtó J, Pröbster L, Frankenberger R (2009) Guidelines for the preparation of CAD/CAM ceramic invasive composite restorations. Gen Dent 59(6):422–428 quiz 429-30 inlays and partial crowns. Int J Comput Dent 12(4):309–325 21. Muller V, Friedl KH, Friedl K, Hahnel S, Handel G, Lang R (2017) 28. Holmes JR, Bayne SC, Holland GA, Sulik WD (1989) Influence of proximal box elevation technique on marginal integrity Considerations in measurement of marginal fit. J Prosthet Dent of adhesively luted Cerec inlays. Clin Oral Investig 21(2):607–612 62(4):405–408 22. Bollen CM, Lambrechts P, Quirynen M (1997) Comparison of sur- 29. Roulet JF, Reich T, Blunck U, Noack M (1989) Quantitative margin face roughness of oral hard materials to the threshold surface rough- analysis in the scanning electron microscope. Scanning Microsc ness for bacterial plaque retention: a review of the literature. Dent 3(1):147–158 discussion 158-9 Mater 13(4):258–269 30. Van Meerbeek B, De Munck J, Mattar D, Van Landuyt K, 23. Senawongse P, Pongprueksa P (2007) Surface roughness of nanofill Lambrechts P (2003) Microtensile bond strengths of an etch&rinse and nanohybrid resin composites after polishing and brushing. J and self-etch adhesive to enamel and dentin as a function of surface Esthet Restor Dent 19(5):265–273 discussion 274-5 treatment. Oper Dent 28(5):647–660 24. Bashetty K, Joshi S (2010) The effect of one-step and multi-step 31. 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Journal

Clinical Oral InvestigationsSpringer Journals

Published: Jun 4, 2018

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