A novel method for periapical microsurgery with the aid of 3D technology: a case report

A novel method for periapical microsurgery with the aid of 3D technology: a case report Background: Three-dimensional (3D) technology has gained wide acceptance in dentistry. It has been used for treatment planning and surgical guidance. This case report presented a novel treatment approach to remove cortical bone and root-end during periapical surgery with the help of Cone-Beam Computed Tomography (CBCT), Computer Aided Design (CAD) and three-dimensional (3D) printing technology. Case presentation: A 37-year-old female patient presented with a large periapical lesion of left maxillary lateral incisor and canine was referred for microsurgical endodontic surgery. The data acquired from a preoperative diagnostic CBCT scan and an intra-oral scan was uploaded into surgical planning software and matched. A template that could be used to locate root-ends and lesion areas was virtually designed based on the data and was fabricated using a 3D printer. With the guidance of the template, the overlying cortical bone and root-end were precisely removed by utilizing a trephine with an external diameter of 4.0 mm. The patient was clinically asymptomatic at a six-month follow-up review. One year after the surgery, the lesion was healing well and no periapical radiolucency was observed on radiographic examination. Conclusions: The digitally designed directional template worked in all aspects to facilitate the periapical surgery as anticipated. The root-ends were accurately located and resected. The surgical procedure was simplified, and the treatment efficiency was improved. This technique minimized the damage and reduced iatrogenic injury. Keywords: 3D printing technology, Endodontic microsurgery, Guided periapical surgery, Root-end resection Background radiographs [3]. The method of locating the root apex is When a radiotransparent periapical lesion measures over to first locate the body of the root substantially coronal to 8to 10 mm in diameter [1] and it is a suspected periapical the apex, where the bone covering the root is thinner. cyst, endodontic surgery is required to remove the cyst Once the root has been located and identified, the bone and a biopsy is needed to confirm histologic diagnosis of covering the root is slowly and carefully removed, working the lesion [2]. in an apical direction until the root apex is identified [5]. A most commonly performed endodontic surgery usually The limitations and disadvantages of the classical surgical involves exposure of the periapical lesion through an oste- method have become apparent due to the rapid advance of otomy, surgical removal of the lesion, removal of part of technology. Firstly, searching for root apex from the the root-end tip [3]. However, the root-end surface some- coronal direction of root end inevitably increases damage times can be difficult to distinguish from the surrounding and risk to non-pathological osseous tissues [4]. Secondly, osseous tissues [4]. conventional radiography shows only two-dimensional In such cases, conventionally, the approximate location images, which does not represent the lesion area accurately of the root-end may be estimated using preoperative and distinctly. Thirdly, it is not easy for inexperienced end- odontic surgeons to balance between limiting damage to * Correspondence: xyang.gmu@gmail.com osseous tissues and gaining enough visual and operative Shangzhu Ye and Shiyong Zhao contributed equally to this work. 1 access for root-end resection and root-end filling [4]. Based Department of Digital Dental Center, Key Laboratory of Oral Medicine, Guangzhou Institute of Oral Disease, Stomatology Hospital of Guangzhou on CBCT, CAD and 3D printing technology, however, Medical University, 59 Huangsha Road, Guangzhou 510140, Guangdong these problems can be solved. Province, China Full list of author information is available at the end of the article © The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Ye et al. BMC Oral Health (2018) 18:85 Page 2 of 7 Rapid prototyping technology, better known as 3D remove the root-ends at the same time to eliminate con- printing, has provided new possibilities for diagnosis, tamination. No contraindications were found. The pa- surgical planning, prosthesis design, and student educa- tient had no significant medical history and was in good tion in medicine. In dentistry, 3D printing technology medical status. has been used for treatment planning, surgical guidance, After obtaining the patient’s informed consent about the and the fabrication of dental models for appliances in surgery procedure and the possible prognosis of the out- orthognathic surgery, implant surgery, oral and maxillo- come, a small volume CBCT scan (iCAT 17–19, Imaging facial surgery, orthodontics, and prosthodontics [6–10]. Sciences International, Hatfield, PA, USA) was taken to The high accuracy of 3D printing and extended flexibil- obtain a more detailed view of the periapical area, to de- ity render this technology very promising [11–15]. In termine the accurate size of the lesion and the exact loca- endodontics, 3D printing has also gained wide applica- tion of root apices, to evaluate the proximity of adjacent tion. Kim et al. [16] fabricated a 3D printed physical anatomical structures and to design a template. A well- tooth model to aid the endodontic treatment of an defined radiolucent lesion with an approximate size of anomalous anterior tooth; a 3D printed template was 13 mm*9 mm*9 mm at the apices of the upper left lateral used in root canal treatment for teeth with pulp canal incisor and canine was observed on CBCT (Fig. 1). An calcification [17], and its accuracy was proven [11]; Shi endodontic specialist treated her with an appropriate root X et al. [18] described the application of a 3D printed canal therapy before the surgery. template for the predictable navigation of obliterated The acquired Digital Imaging and Communications in canal systems during root canal treatment to avoid iatro- Medicine (DICOM) files from the CBCT images were genic damage of the root [18]; In endodontic surgery, a uploaded into a software (Simplant, Leuven Belgium) for 3D printed retractor was invented and fabricated for soft virtual surgical planning. A digital impression was ac- tissue retraction [8]. quired with an intra-oral scanner (3Shape, Denmark) This case report describes a novel method for guided and uploaded into the same software. Both the CBCT periapical surgery, which removed overlying cortical and the surface scan were matched based on radiograph- bone and root-end precisely with the aid of a 3D-printed ically visible teeth. A template was virtually designed to surgical template. locate the lesion area and the root apex of the teeth pre- cisely (Fig. 2a and b). The thickness of labial cortical Case Presentation bone was gauged using a virtual measure tool provided A 37-year-old female patient presented with discomfort by the software and recorded as working depth I. The in the left maxillary lateral incisor. Clinical examination straight distance from the surface of the labial cortical revealed that the left maxillary lateral incisor and canine bone to the palatal side of the root-end requiring resec- were slightly tender to percussion. Pulp vitality test tion was also gauged and recorded as working depth II. showed a negative response to temperature for both The distance from the palatal side of the root-end to the teeth. Radiograph showed a large periapical radiolucency labial side of the palatal alveolar bone was also gauged around both teeth. The patient was clinically diagnosed and recorded as safe depth to prevent the trephine from with chronic periapical periodontitis. Considering the entering too deeply into the bone and causing unneces- large size of the periapical lesion and it was a suspected sary damage to the palatal alveolar bone (Fig. 2c and d). periapical cyst, we decided to treat the patient with a During the surgery, the thickness of the template (2.0 mm) microsurgical endodontic surgery for biopsy and to and the space reserved for soft tissue (0.5 mm) was added Fig. 1 a, b Sagittal CBCT images of the left maxillary lateral incisor and canine showed lesions in periradicular regions. c An oblique coronal CBCT image revealed that the teeth shared one elliptic lesion with an approximate size of 13 mm*9 mm*9 mm. The red arrow indicates the location of the lesion Ye et al. BMC Oral Health (2018) 18:85 Page 3 of 7 Fig. 2 a A 3 mm root-end for resection was marked by a simulated virtual trephine with a diameter of 4 mm on an oblique coronal section of the left maxillary lateral incisor and canine. The root-ends of the left maxillary central incisor and first premolar were safe from accidental damage. b A horizontal section indicated the location of root-ends for both teeth and the root-ends were marked by the simulated virtual trephine. c Based on a sagittal section of the left maxillary lateral incisor, we learned that a working depth of 4.57 mm would be sufficient for the trephine to remove the root-end completely. This depth was still 2.69 mm away from the palatal cortical bone, which we regarded as a safe depth. d For the left maxillary canine, the working depth was 4.87 mm, and the safe depth was 2.19 mm. All lengths were measured using a tool provided by the software. e Three-dimensional reconstruction of the scans obtained from CBCT and surface scans were matched to reconstruct the operating site. f The locations of the root-ends of the left maxillary lateral incisor and canine were marked out on the reconstruction image. g The template was designed to be supported by teeth from the left maxillary central incisor to the left maxillary first premolar. The lesion area was located, and the outline was confirmed. h The template was designed to be 2 mm thick after considering the flexural strength of the resin composite. A 0.5 mm space from the labial cortical plate to the template was preserved to accommodate soft tissues to the working depth I and II to obtain total working depth Iand II. To guide and accommodate a trephine (Meisinger, Germany) with an external diameter of 4.0 mm, the round hollow part aimed to locate the root-end was designed with a diameter of 4.2 mm, which was enough to hold the trephine but not so large as to destroy accur- acy. To preserve more root length and avoid exposing more dentinal tubules, the track guiding the trephine was designed to be perpendicular to the long axis of the root. The other hollow part lying in the middle followed the outline of the lesion, locating the whole part of the lesion precisely (Fig. 2e, f, g and h). The virtual template was exported as a stereolithography (STL) file and was fabricated using a 3D printer (3510SD, 3D system Corporation, Rock Hills, SC, USA) (Fig. 3a). After fabrication, the template was positioned on the patient’s plaster cast, and its correct and reproducible fitting was checked. It was then detached and soaked in disinfectant for use. Another fitness check was per- formed on the real teeth of the patient before surgery (Fig. 3b). After disinfection of the skin and mucosa, primacaine Fig. 3 a The template was fabricated exactly as designed with an was delivered into the loose connective tissue of the equivalent thickness. b The disinfected template was positioned on the alveolar mucosa near the root apices for local anaesthe- real teeth and checked. c A full-thickness marginal flap was prepared sia. A rectangular, full-thickness flap design was chosen with a primary incision in the gingival sulcus and the relieving incision as in this case (Fig. 3c). The mucoperiosteum was reflected, vertical as possible to avoid severing supra-periosteal vessels and collagen fibres. d The reflection of the flap and the exposure of the and the labial alveolar plate was exposed where a semi- lesion. e Sling suture to the buccal mucosa. f The template was placed lunar perforation was observed (Fig. 3d). We sutured the in position and checked flap to the labial mucosa (Fig. 3e). Ye et al. BMC Oral Health (2018) 18:85 Page 4 of 7 Fig. 4 a The trephine was positioned. b After the trephine reached total working depth I and was removed, the annular notches were observed. c The template was removed and the operating site was inspected. d The pathological tissues were removed for biopsy The template was positioned on the teeth and was (Fig. 5f). Pressure was applied for ten minutes after checked again for stability, a clear operating vision and a suturing. Biopsy findings were periapical granuloma straight access to the cortical bone (Fig. 3f). The tre- (Fig. 6a and b). phine was laid inside the pre-designed track and was The patient was reviewed 7 days later to remove slowly and carefully pushed in with the guidance of the stitches. The operating site was healing well, and no template with constant sterile saline flushing (Fig. 4a). unusual symptoms or postoperative discomforts were The trephine was removed when it reached total work- reported by the patient (Fig. 7a and b). ing depth I which was pre-gauged on the CBCT images, leaving an annular notch (Fig. 4b). The template was de- tached to inspect the operating site (Fig. 4c). The annu- lar cortical bone was gently removed to expose the pathological tissues. The left maxillary lateral incisor and canine were both operated on in the same way, but the total working depth was different in each case. Other soft pathological tissues between the two root-ends were easily removed with suitable sizes of sharp surgical bone curettes (Fig. 4d). The removed pathological tissues were sent for histopathological examination. The template was positioned again after the removal of pathological tissues. The trephine was laid inside and when it reached total working depth II, a sense of dropping was felt through the trephine just as the root-end was separated entirely from the tooth, forming a cutting bevel at the resected root-end perpendicular to the long axis of the canal. Root-end cavity preparation was carried out using an angled micro-surgical ultrasonic tip under a microscope. The root-end cavity was prepared, cleaned and dried. Mineral trioxide aggregate (MTA) was filled into the cavity (Fig. 5a and b). Considering the large size of the Fig. 5 a, b Micro-surgical mirror was used to examine the cut root lesion (Fig. 5c), a guided tissue regeneration (GTR) pro- surface after the MTA was delivered into the root-end. Completed cedure was adopted for better healing. It was carried out MTA root-end filling was obtained. c After removal and cleaning of soft pathological tissue, the lesion size was large and required a GTR using xenogeneic bone (Geistlich Bio-Oss, Switzerland) procedure for better prognosis. d, e Bio-Oss and Bio-Guide were and collagen membrane (Geistlich Bio-Gide, Switzerland; used in this case. f The flap was sutured back Fig. 5d and e). The flap was gently eased back and sutured Ye et al. BMC Oral Health (2018) 18:85 Page 5 of 7 Fig. 6 Histopathologic examination revealed the presence of (a) eosinophils (red arrows), foam cells (black arrows) and areas of hemosiderin pigmentation (green arrows; H&E, 40×); b plasma cell (red arrow) and many lymphocytes (black arrows; H&E, 40×). The features were consistent with periapical granuloma A six-month review showed evidence of bony healing obtained from CBCT and digital surface scans could be and both teeth were symptom-free (Fig. 7c, d and e). integrated into a physical template. One year after the surgery, the patient was asymptom- In a conventional periapical surgical process, searching atic clinically and showed complete bony healing. No for root-end and the need for adequate operative visual periapical radiolucency was observed on radiographic field usually leave a large bone defect which seems examination (Fig. 7f). unnecessary now [19]. With the aid of the 3D printed template, the diameter of the lesion caused by surgery could be restricted to 3–4 mm, only slightly larger than Discussion and conclusions the length of resection (3 mm). This minimal invasive Endodontic surgery is needed for the treatment of a surgical procedure maximally limits injury to osseous large, cyst-like periapical lesion [1, 2]. Sometimes it is tissues. Less damage to osseous tissues results in less challenging to locate root-end for resection [4]. The haemorrhage during surgery, less postoperative compli- length of resection of root-end (3 mm) is not easy to cations, shorter healing time and better prognosis. control for inexperienced surgeons. Here, a novel The template served as a carrier, carrying the informa- method was used to solve these problems with the guide tion of the location of the root-end and the size of the of a 3D-printed template. This template was fabricated periapical lesion, the orientation and angle of the root following data acquisition, image processing and manu- and its apex, and the thickness of the cortical bone into facturing, through which the combined information the surgical procedure. With the aid of the template, the Fig. 7 a A 7-day review to remove the sutures. b The mucosa at the operating site was healing well. c The incisions healed well at a six-month review. d A sagittal section from a six-month review CBCT showed evidence of bony healing of the left maxillary lateral incisor. e The same was true of the left maxillary canine. f One-year follow up radiographic examination showed complete healing of the periapical lesion of both teeth and no periapical radiolucency was observed. The red arrow indicates the surgical site Ye et al. BMC Oral Health (2018) 18:85 Page 6 of 7 trephine was navigated into the exact location, and the Acknowledgements The design and fabrication of the template were supported by Technician surgeons did not have to mentally transfer the informa- Mr. Zeng Huajiang. tion to the clinical situation. This procedure enabled the surgeons to precisely remove the overlying bone and the Funding This work was supported by a grant from the Science and Technology root-end using the trephine. This method not only Planning Project of Liwan District of Guangzhou City, China (No. simplified the surgical procedure but also considerably 20151217075) and a special fund for International Cooperation from the improved the treatment efficiency. More time was Science and Technology Planning Project, Guangdong Province, China (No. 2017A050501054). The funding body aided us financially in designing and needed preoperatively to virtually design the template. fabricating the template, purchasing materials used in the case, publishing However, the time will surely be reduced in the future the paper. once a workflow is established. Availability of data and materials Adjacent teeth and bone were saved from accidental The complete data and materials described in the case report are freely damage with the restriction of the template. This pro- available from the corresponding author on reasonable request. cedure eliminated the unpredictability of osteotomy and root end resection, rendering a challenging clinical pro- Authors’ contributions The roles of the authors were: SZY, SYZ analyzed the patient’s CBCT images cedure relatively simple to manage. The 3D technology and surface scan images, designed a template, and were major contributors described has the potential to substitute for the special- in writing the manuscript. WDW, QZJ performed the biopsy examination of ized training and/or clinical experience necessary to the pathological tissues. XCY treated the patient with a microsurgical endodontic surgery. All the authors have read and approved the final treat these difficult cases, which would enable many manuscript. dentists to achieve predictable results without needing extensive surgical skills. Ethics approval and consent to participate All the treatment protocols of the case report were approved by the Ethics A slight mismatch between planning and execution Committee of Stomatology Hospital, Guangzhou Medical University, (KY-2017-012). may be expected if we consider the accuracy of this 3D planning technology. Further studies need to be Consent for publication carried out to confirm the accuracy of the 3D-printed Written informed consent for publication of clinical details and clinical images was obtained from the patient. A copy of the consent form is template-aided periapical surgery procedure. The uni- available for review by the Editor of this journal. formity can be checked by comparing pre and post- operative virtual images. Competing interests The authors declare that they have no competing interests. This procedure still has some limitations. When the lesion is in a posterior region, the template can still be Publisher’sNote fabricated and positioned, but insufficient space will be Springer Nature remains neutral with regard to jurisdictional claims in available for the trephine. The costs of such 3D planning published maps and institutional affiliations. and the production of the directional template are con- Author details sidered high; however, such costs will be reduced in the Department of Digital Dental Center, Key Laboratory of Oral Medicine, future given the fast-paced development of digital tech- Guangzhou Institute of Oral Disease, Stomatology Hospital of Guangzhou nology in dentistry. There is a promising chance that a Medical University, 59 Huangsha Road, Guangzhou 510140, Guangdong Province, China. Department of Endodontics, Key Laboratory of Oral reasonable therapy workflow will be established and this Medicine, Guangzhou Institute of Oral Disease, Stomatology Hospital of treatment approach will be applied in daily routine prac- Guangzhou Medical University, 39 Huangsha Road, Guangzhou, Guangdong tice, benefiting more patients. Province, China. The digitally designed directional template fabri- Received: 29 December 2017 Accepted: 27 April 2018 cated using CBCT, CAD and 3D printing technology worked in all aspects to facilitate the periapical surgery as anticipated. The root-ends were accurately References 1. Peñarrocha M, Martí E, García B, Gay C. Relationship of periapical lesion located using the template and resected with the tre- radiologicsize, apical resection, and retrograde filling with the prognosis of phine. The surgical procedure was simplified, and periapical surgery. J Oral Maxillofac Surg. 2007;65(8):1526–9. the treatment efficiency was improved. This tech- 2. Shekhar V, Shashikala K. Cone beam computed tomography evaluation of the diagnosis, treatment planning, and long-term followup of large nique minimized the damage to soft and hard tissues periapical lesions treated by endodontic surgery: two case reports. Case Rep and reduced iatrogenic injury. Dent. 2013;2013(1):564392. 3. Fabbro MD, Corbella S, Sequeira-Byron P, Tsesis I, Rosen E, Lolato A, et al. Endodontic procedures for retreatment of periapical lesions. Cochrane Database Syst Rev. 2016;10:CD005511. 4. Morrow SG, Rubinstein RA. Endodontic surgery. JI Ingle and LK Bakland Abbreviations (eds). Endodontics. 2002:690–692. 3D: three-dimensional; CAD: Computer aided design; CBCT: Cone-beam 5. Pop I. Oral surgery: part 2. Endodontic surgery. Br Dent J. 2013;215:279–86. computed tomography; DICOM: Digital imaging and communications in 6. Sun J, Zhang FQ. The application of rapid prototyping in prosthodontics. J medicine; GTR: Guided tissue regeneration; MTA: Mineral trioxide aggregate; Prosthodont. 2012;21(8):641–4. STL: Stereolithography 7. Hems E, Knott NJ. 3D printing in prosthodontics. FDJ. 2014;5(4):152–7. Ye et al. BMC Oral Health (2018) 18:85 Page 7 of 7 8. Patel S, Aldowaisan A, Dawood A. A novel method for soft tissue retraction during periapical surgery using 3D technology: a case report. Int Endod J. 2017;50(8):813–22. 9. Liu A, Xue G, Sun M, Shao H, Ma C, Gao Q, et al. 3D printing surgical implants at the clinic: a experimental study on anterior cruciate ligament reconstruction. Sci Rep. 2016;6(57):84–7. 10. Shaheen E, Sun Y, Jacobs R, Politis C. Three-dimensional printed final occlusal splint for orthognathic surgery: design and validation. Int J Oral Maxillofac Surg. 2016;46(1):67–71. 11. Zehnder MS, Connert T, Weiger R, Krastl G, Kühl S. Guided endodontics: accuracy of a novel method for guided access cavity preparation and root canal location. Int Endod J. 2016;49(10):966–72. 12. Kernen F, Benic GI, Payer M, Filippi A. Accuracy of three-dimensional printed templates for guided implant placement based on matching a surface scan with CBCT. Clin Implant Dent Relat Res. 2016;18(4):762–8. 13. Yamashita M, Matsumoto N, Cho B, Komune N, Onogi S, Lee J, et al. Registration using 3D-printed rigid templates outperforms manually scanned surface matching in image-guided temporal bone surgery. Int J Comput Assist Radiol Surg. 2016;11(11):2119–27. 14. Zhang N, Liu S, Hu Z, Hu J, Zhu S, Li Y. Accuracy of virtual surgical planning in two-jaw orthognathic surgery: comparison of planned and actual results. Oral Surg Oral Med Oral Pathol Oral Radiol. 2016;122(2):143–51. 15. Heike R, Harald S, Matthias M, Katharina K, Viktor S, Bernd W, et al. Accuracy of intraoral and extraoral digital data acquisition for dental restorations. J Appl Oral Sci. 2016;24(1):85–94. 16. Byun C, Kim C, Cho S, Baek SH, Kim G, Kim SG, et al. Endodontic treatment of an anomalous anterior tooth with the aid of a 3-dimensional printed physical tooth model. J Endod. 2015;41(6):961–5. 17. Krastl G, Zehnder MS, Connert T, Weiger R, Kühl S. Guided endodontics: a novel treatment approach for teeth with pulp canal calcification and apical pathology. Dent Traumatol. 2016;32(3):240–6. 18. Shi X, Zhao S, Wang W, Jiang Q, Yang X. Novel navigation technique for the endodontic treatment of a molar with pulp canal calcification and apical pathology. Aust Endod J. 2017;44:66–70. 19. Lin L, Chen MY, Ricucci D, Rosenberg PA. Guided tissue regeneration in periapical surgery. J Endod. 2010;36(4):618–25. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png BMC Oral Health Springer Journals

A novel method for periapical microsurgery with the aid of 3D technology: a case report

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Abstract

Background: Three-dimensional (3D) technology has gained wide acceptance in dentistry. It has been used for treatment planning and surgical guidance. This case report presented a novel treatment approach to remove cortical bone and root-end during periapical surgery with the help of Cone-Beam Computed Tomography (CBCT), Computer Aided Design (CAD) and three-dimensional (3D) printing technology. Case presentation: A 37-year-old female patient presented with a large periapical lesion of left maxillary lateral incisor and canine was referred for microsurgical endodontic surgery. The data acquired from a preoperative diagnostic CBCT scan and an intra-oral scan was uploaded into surgical planning software and matched. A template that could be used to locate root-ends and lesion areas was virtually designed based on the data and was fabricated using a 3D printer. With the guidance of the template, the overlying cortical bone and root-end were precisely removed by utilizing a trephine with an external diameter of 4.0 mm. The patient was clinically asymptomatic at a six-month follow-up review. One year after the surgery, the lesion was healing well and no periapical radiolucency was observed on radiographic examination. Conclusions: The digitally designed directional template worked in all aspects to facilitate the periapical surgery as anticipated. The root-ends were accurately located and resected. The surgical procedure was simplified, and the treatment efficiency was improved. This technique minimized the damage and reduced iatrogenic injury. Keywords: 3D printing technology, Endodontic microsurgery, Guided periapical surgery, Root-end resection Background radiographs [3]. The method of locating the root apex is When a radiotransparent periapical lesion measures over to first locate the body of the root substantially coronal to 8to 10 mm in diameter [1] and it is a suspected periapical the apex, where the bone covering the root is thinner. cyst, endodontic surgery is required to remove the cyst Once the root has been located and identified, the bone and a biopsy is needed to confirm histologic diagnosis of covering the root is slowly and carefully removed, working the lesion [2]. in an apical direction until the root apex is identified [5]. A most commonly performed endodontic surgery usually The limitations and disadvantages of the classical surgical involves exposure of the periapical lesion through an oste- method have become apparent due to the rapid advance of otomy, surgical removal of the lesion, removal of part of technology. Firstly, searching for root apex from the the root-end tip [3]. However, the root-end surface some- coronal direction of root end inevitably increases damage times can be difficult to distinguish from the surrounding and risk to non-pathological osseous tissues [4]. Secondly, osseous tissues [4]. conventional radiography shows only two-dimensional In such cases, conventionally, the approximate location images, which does not represent the lesion area accurately of the root-end may be estimated using preoperative and distinctly. Thirdly, it is not easy for inexperienced end- odontic surgeons to balance between limiting damage to * Correspondence: xyang.gmu@gmail.com osseous tissues and gaining enough visual and operative Shangzhu Ye and Shiyong Zhao contributed equally to this work. 1 access for root-end resection and root-end filling [4]. Based Department of Digital Dental Center, Key Laboratory of Oral Medicine, Guangzhou Institute of Oral Disease, Stomatology Hospital of Guangzhou on CBCT, CAD and 3D printing technology, however, Medical University, 59 Huangsha Road, Guangzhou 510140, Guangdong these problems can be solved. Province, China Full list of author information is available at the end of the article © The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Ye et al. BMC Oral Health (2018) 18:85 Page 2 of 7 Rapid prototyping technology, better known as 3D remove the root-ends at the same time to eliminate con- printing, has provided new possibilities for diagnosis, tamination. No contraindications were found. The pa- surgical planning, prosthesis design, and student educa- tient had no significant medical history and was in good tion in medicine. In dentistry, 3D printing technology medical status. has been used for treatment planning, surgical guidance, After obtaining the patient’s informed consent about the and the fabrication of dental models for appliances in surgery procedure and the possible prognosis of the out- orthognathic surgery, implant surgery, oral and maxillo- come, a small volume CBCT scan (iCAT 17–19, Imaging facial surgery, orthodontics, and prosthodontics [6–10]. Sciences International, Hatfield, PA, USA) was taken to The high accuracy of 3D printing and extended flexibil- obtain a more detailed view of the periapical area, to de- ity render this technology very promising [11–15]. In termine the accurate size of the lesion and the exact loca- endodontics, 3D printing has also gained wide applica- tion of root apices, to evaluate the proximity of adjacent tion. Kim et al. [16] fabricated a 3D printed physical anatomical structures and to design a template. A well- tooth model to aid the endodontic treatment of an defined radiolucent lesion with an approximate size of anomalous anterior tooth; a 3D printed template was 13 mm*9 mm*9 mm at the apices of the upper left lateral used in root canal treatment for teeth with pulp canal incisor and canine was observed on CBCT (Fig. 1). An calcification [17], and its accuracy was proven [11]; Shi endodontic specialist treated her with an appropriate root X et al. [18] described the application of a 3D printed canal therapy before the surgery. template for the predictable navigation of obliterated The acquired Digital Imaging and Communications in canal systems during root canal treatment to avoid iatro- Medicine (DICOM) files from the CBCT images were genic damage of the root [18]; In endodontic surgery, a uploaded into a software (Simplant, Leuven Belgium) for 3D printed retractor was invented and fabricated for soft virtual surgical planning. A digital impression was ac- tissue retraction [8]. quired with an intra-oral scanner (3Shape, Denmark) This case report describes a novel method for guided and uploaded into the same software. Both the CBCT periapical surgery, which removed overlying cortical and the surface scan were matched based on radiograph- bone and root-end precisely with the aid of a 3D-printed ically visible teeth. A template was virtually designed to surgical template. locate the lesion area and the root apex of the teeth pre- cisely (Fig. 2a and b). The thickness of labial cortical Case Presentation bone was gauged using a virtual measure tool provided A 37-year-old female patient presented with discomfort by the software and recorded as working depth I. The in the left maxillary lateral incisor. Clinical examination straight distance from the surface of the labial cortical revealed that the left maxillary lateral incisor and canine bone to the palatal side of the root-end requiring resec- were slightly tender to percussion. Pulp vitality test tion was also gauged and recorded as working depth II. showed a negative response to temperature for both The distance from the palatal side of the root-end to the teeth. Radiograph showed a large periapical radiolucency labial side of the palatal alveolar bone was also gauged around both teeth. The patient was clinically diagnosed and recorded as safe depth to prevent the trephine from with chronic periapical periodontitis. Considering the entering too deeply into the bone and causing unneces- large size of the periapical lesion and it was a suspected sary damage to the palatal alveolar bone (Fig. 2c and d). periapical cyst, we decided to treat the patient with a During the surgery, the thickness of the template (2.0 mm) microsurgical endodontic surgery for biopsy and to and the space reserved for soft tissue (0.5 mm) was added Fig. 1 a, b Sagittal CBCT images of the left maxillary lateral incisor and canine showed lesions in periradicular regions. c An oblique coronal CBCT image revealed that the teeth shared one elliptic lesion with an approximate size of 13 mm*9 mm*9 mm. The red arrow indicates the location of the lesion Ye et al. BMC Oral Health (2018) 18:85 Page 3 of 7 Fig. 2 a A 3 mm root-end for resection was marked by a simulated virtual trephine with a diameter of 4 mm on an oblique coronal section of the left maxillary lateral incisor and canine. The root-ends of the left maxillary central incisor and first premolar were safe from accidental damage. b A horizontal section indicated the location of root-ends for both teeth and the root-ends were marked by the simulated virtual trephine. c Based on a sagittal section of the left maxillary lateral incisor, we learned that a working depth of 4.57 mm would be sufficient for the trephine to remove the root-end completely. This depth was still 2.69 mm away from the palatal cortical bone, which we regarded as a safe depth. d For the left maxillary canine, the working depth was 4.87 mm, and the safe depth was 2.19 mm. All lengths were measured using a tool provided by the software. e Three-dimensional reconstruction of the scans obtained from CBCT and surface scans were matched to reconstruct the operating site. f The locations of the root-ends of the left maxillary lateral incisor and canine were marked out on the reconstruction image. g The template was designed to be supported by teeth from the left maxillary central incisor to the left maxillary first premolar. The lesion area was located, and the outline was confirmed. h The template was designed to be 2 mm thick after considering the flexural strength of the resin composite. A 0.5 mm space from the labial cortical plate to the template was preserved to accommodate soft tissues to the working depth I and II to obtain total working depth Iand II. To guide and accommodate a trephine (Meisinger, Germany) with an external diameter of 4.0 mm, the round hollow part aimed to locate the root-end was designed with a diameter of 4.2 mm, which was enough to hold the trephine but not so large as to destroy accur- acy. To preserve more root length and avoid exposing more dentinal tubules, the track guiding the trephine was designed to be perpendicular to the long axis of the root. The other hollow part lying in the middle followed the outline of the lesion, locating the whole part of the lesion precisely (Fig. 2e, f, g and h). The virtual template was exported as a stereolithography (STL) file and was fabricated using a 3D printer (3510SD, 3D system Corporation, Rock Hills, SC, USA) (Fig. 3a). After fabrication, the template was positioned on the patient’s plaster cast, and its correct and reproducible fitting was checked. It was then detached and soaked in disinfectant for use. Another fitness check was per- formed on the real teeth of the patient before surgery (Fig. 3b). After disinfection of the skin and mucosa, primacaine Fig. 3 a The template was fabricated exactly as designed with an was delivered into the loose connective tissue of the equivalent thickness. b The disinfected template was positioned on the alveolar mucosa near the root apices for local anaesthe- real teeth and checked. c A full-thickness marginal flap was prepared sia. A rectangular, full-thickness flap design was chosen with a primary incision in the gingival sulcus and the relieving incision as in this case (Fig. 3c). The mucoperiosteum was reflected, vertical as possible to avoid severing supra-periosteal vessels and collagen fibres. d The reflection of the flap and the exposure of the and the labial alveolar plate was exposed where a semi- lesion. e Sling suture to the buccal mucosa. f The template was placed lunar perforation was observed (Fig. 3d). We sutured the in position and checked flap to the labial mucosa (Fig. 3e). Ye et al. BMC Oral Health (2018) 18:85 Page 4 of 7 Fig. 4 a The trephine was positioned. b After the trephine reached total working depth I and was removed, the annular notches were observed. c The template was removed and the operating site was inspected. d The pathological tissues were removed for biopsy The template was positioned on the teeth and was (Fig. 5f). Pressure was applied for ten minutes after checked again for stability, a clear operating vision and a suturing. Biopsy findings were periapical granuloma straight access to the cortical bone (Fig. 3f). The tre- (Fig. 6a and b). phine was laid inside the pre-designed track and was The patient was reviewed 7 days later to remove slowly and carefully pushed in with the guidance of the stitches. The operating site was healing well, and no template with constant sterile saline flushing (Fig. 4a). unusual symptoms or postoperative discomforts were The trephine was removed when it reached total work- reported by the patient (Fig. 7a and b). ing depth I which was pre-gauged on the CBCT images, leaving an annular notch (Fig. 4b). The template was de- tached to inspect the operating site (Fig. 4c). The annu- lar cortical bone was gently removed to expose the pathological tissues. The left maxillary lateral incisor and canine were both operated on in the same way, but the total working depth was different in each case. Other soft pathological tissues between the two root-ends were easily removed with suitable sizes of sharp surgical bone curettes (Fig. 4d). The removed pathological tissues were sent for histopathological examination. The template was positioned again after the removal of pathological tissues. The trephine was laid inside and when it reached total working depth II, a sense of dropping was felt through the trephine just as the root-end was separated entirely from the tooth, forming a cutting bevel at the resected root-end perpendicular to the long axis of the canal. Root-end cavity preparation was carried out using an angled micro-surgical ultrasonic tip under a microscope. The root-end cavity was prepared, cleaned and dried. Mineral trioxide aggregate (MTA) was filled into the cavity (Fig. 5a and b). Considering the large size of the Fig. 5 a, b Micro-surgical mirror was used to examine the cut root lesion (Fig. 5c), a guided tissue regeneration (GTR) pro- surface after the MTA was delivered into the root-end. Completed cedure was adopted for better healing. It was carried out MTA root-end filling was obtained. c After removal and cleaning of soft pathological tissue, the lesion size was large and required a GTR using xenogeneic bone (Geistlich Bio-Oss, Switzerland) procedure for better prognosis. d, e Bio-Oss and Bio-Guide were and collagen membrane (Geistlich Bio-Gide, Switzerland; used in this case. f The flap was sutured back Fig. 5d and e). The flap was gently eased back and sutured Ye et al. BMC Oral Health (2018) 18:85 Page 5 of 7 Fig. 6 Histopathologic examination revealed the presence of (a) eosinophils (red arrows), foam cells (black arrows) and areas of hemosiderin pigmentation (green arrows; H&E, 40×); b plasma cell (red arrow) and many lymphocytes (black arrows; H&E, 40×). The features were consistent with periapical granuloma A six-month review showed evidence of bony healing obtained from CBCT and digital surface scans could be and both teeth were symptom-free (Fig. 7c, d and e). integrated into a physical template. One year after the surgery, the patient was asymptom- In a conventional periapical surgical process, searching atic clinically and showed complete bony healing. No for root-end and the need for adequate operative visual periapical radiolucency was observed on radiographic field usually leave a large bone defect which seems examination (Fig. 7f). unnecessary now [19]. With the aid of the 3D printed template, the diameter of the lesion caused by surgery could be restricted to 3–4 mm, only slightly larger than Discussion and conclusions the length of resection (3 mm). This minimal invasive Endodontic surgery is needed for the treatment of a surgical procedure maximally limits injury to osseous large, cyst-like periapical lesion [1, 2]. Sometimes it is tissues. Less damage to osseous tissues results in less challenging to locate root-end for resection [4]. The haemorrhage during surgery, less postoperative compli- length of resection of root-end (3 mm) is not easy to cations, shorter healing time and better prognosis. control for inexperienced surgeons. Here, a novel The template served as a carrier, carrying the informa- method was used to solve these problems with the guide tion of the location of the root-end and the size of the of a 3D-printed template. This template was fabricated periapical lesion, the orientation and angle of the root following data acquisition, image processing and manu- and its apex, and the thickness of the cortical bone into facturing, through which the combined information the surgical procedure. With the aid of the template, the Fig. 7 a A 7-day review to remove the sutures. b The mucosa at the operating site was healing well. c The incisions healed well at a six-month review. d A sagittal section from a six-month review CBCT showed evidence of bony healing of the left maxillary lateral incisor. e The same was true of the left maxillary canine. f One-year follow up radiographic examination showed complete healing of the periapical lesion of both teeth and no periapical radiolucency was observed. The red arrow indicates the surgical site Ye et al. BMC Oral Health (2018) 18:85 Page 6 of 7 trephine was navigated into the exact location, and the Acknowledgements The design and fabrication of the template were supported by Technician surgeons did not have to mentally transfer the informa- Mr. Zeng Huajiang. tion to the clinical situation. This procedure enabled the surgeons to precisely remove the overlying bone and the Funding This work was supported by a grant from the Science and Technology root-end using the trephine. This method not only Planning Project of Liwan District of Guangzhou City, China (No. simplified the surgical procedure but also considerably 20151217075) and a special fund for International Cooperation from the improved the treatment efficiency. More time was Science and Technology Planning Project, Guangdong Province, China (No. 2017A050501054). The funding body aided us financially in designing and needed preoperatively to virtually design the template. fabricating the template, purchasing materials used in the case, publishing However, the time will surely be reduced in the future the paper. once a workflow is established. Availability of data and materials Adjacent teeth and bone were saved from accidental The complete data and materials described in the case report are freely damage with the restriction of the template. This pro- available from the corresponding author on reasonable request. cedure eliminated the unpredictability of osteotomy and root end resection, rendering a challenging clinical pro- Authors’ contributions The roles of the authors were: SZY, SYZ analyzed the patient’s CBCT images cedure relatively simple to manage. The 3D technology and surface scan images, designed a template, and were major contributors described has the potential to substitute for the special- in writing the manuscript. WDW, QZJ performed the biopsy examination of ized training and/or clinical experience necessary to the pathological tissues. XCY treated the patient with a microsurgical endodontic surgery. All the authors have read and approved the final treat these difficult cases, which would enable many manuscript. dentists to achieve predictable results without needing extensive surgical skills. Ethics approval and consent to participate All the treatment protocols of the case report were approved by the Ethics A slight mismatch between planning and execution Committee of Stomatology Hospital, Guangzhou Medical University, (KY-2017-012). may be expected if we consider the accuracy of this 3D planning technology. Further studies need to be Consent for publication carried out to confirm the accuracy of the 3D-printed Written informed consent for publication of clinical details and clinical images was obtained from the patient. A copy of the consent form is template-aided periapical surgery procedure. The uni- available for review by the Editor of this journal. formity can be checked by comparing pre and post- operative virtual images. Competing interests The authors declare that they have no competing interests. This procedure still has some limitations. When the lesion is in a posterior region, the template can still be Publisher’sNote fabricated and positioned, but insufficient space will be Springer Nature remains neutral with regard to jurisdictional claims in available for the trephine. The costs of such 3D planning published maps and institutional affiliations. and the production of the directional template are con- Author details sidered high; however, such costs will be reduced in the Department of Digital Dental Center, Key Laboratory of Oral Medicine, future given the fast-paced development of digital tech- Guangzhou Institute of Oral Disease, Stomatology Hospital of Guangzhou nology in dentistry. There is a promising chance that a Medical University, 59 Huangsha Road, Guangzhou 510140, Guangdong Province, China. Department of Endodontics, Key Laboratory of Oral reasonable therapy workflow will be established and this Medicine, Guangzhou Institute of Oral Disease, Stomatology Hospital of treatment approach will be applied in daily routine prac- Guangzhou Medical University, 39 Huangsha Road, Guangzhou, Guangdong tice, benefiting more patients. Province, China. The digitally designed directional template fabri- Received: 29 December 2017 Accepted: 27 April 2018 cated using CBCT, CAD and 3D printing technology worked in all aspects to facilitate the periapical surgery as anticipated. The root-ends were accurately References 1. Peñarrocha M, Martí E, García B, Gay C. Relationship of periapical lesion located using the template and resected with the tre- radiologicsize, apical resection, and retrograde filling with the prognosis of phine. The surgical procedure was simplified, and periapical surgery. J Oral Maxillofac Surg. 2007;65(8):1526–9. the treatment efficiency was improved. This tech- 2. Shekhar V, Shashikala K. Cone beam computed tomography evaluation of the diagnosis, treatment planning, and long-term followup of large nique minimized the damage to soft and hard tissues periapical lesions treated by endodontic surgery: two case reports. Case Rep and reduced iatrogenic injury. Dent. 2013;2013(1):564392. 3. Fabbro MD, Corbella S, Sequeira-Byron P, Tsesis I, Rosen E, Lolato A, et al. Endodontic procedures for retreatment of periapical lesions. Cochrane Database Syst Rev. 2016;10:CD005511. 4. Morrow SG, Rubinstein RA. Endodontic surgery. JI Ingle and LK Bakland Abbreviations (eds). Endodontics. 2002:690–692. 3D: three-dimensional; CAD: Computer aided design; CBCT: Cone-beam 5. Pop I. Oral surgery: part 2. Endodontic surgery. Br Dent J. 2013;215:279–86. computed tomography; DICOM: Digital imaging and communications in 6. Sun J, Zhang FQ. The application of rapid prototyping in prosthodontics. J medicine; GTR: Guided tissue regeneration; MTA: Mineral trioxide aggregate; Prosthodont. 2012;21(8):641–4. STL: Stereolithography 7. Hems E, Knott NJ. 3D printing in prosthodontics. FDJ. 2014;5(4):152–7. Ye et al. BMC Oral Health (2018) 18:85 Page 7 of 7 8. Patel S, Aldowaisan A, Dawood A. A novel method for soft tissue retraction during periapical surgery using 3D technology: a case report. Int Endod J. 2017;50(8):813–22. 9. Liu A, Xue G, Sun M, Shao H, Ma C, Gao Q, et al. 3D printing surgical implants at the clinic: a experimental study on anterior cruciate ligament reconstruction. Sci Rep. 2016;6(57):84–7. 10. Shaheen E, Sun Y, Jacobs R, Politis C. Three-dimensional printed final occlusal splint for orthognathic surgery: design and validation. Int J Oral Maxillofac Surg. 2016;46(1):67–71. 11. Zehnder MS, Connert T, Weiger R, Krastl G, Kühl S. Guided endodontics: accuracy of a novel method for guided access cavity preparation and root canal location. Int Endod J. 2016;49(10):966–72. 12. Kernen F, Benic GI, Payer M, Filippi A. Accuracy of three-dimensional printed templates for guided implant placement based on matching a surface scan with CBCT. Clin Implant Dent Relat Res. 2016;18(4):762–8. 13. Yamashita M, Matsumoto N, Cho B, Komune N, Onogi S, Lee J, et al. Registration using 3D-printed rigid templates outperforms manually scanned surface matching in image-guided temporal bone surgery. Int J Comput Assist Radiol Surg. 2016;11(11):2119–27. 14. Zhang N, Liu S, Hu Z, Hu J, Zhu S, Li Y. Accuracy of virtual surgical planning in two-jaw orthognathic surgery: comparison of planned and actual results. Oral Surg Oral Med Oral Pathol Oral Radiol. 2016;122(2):143–51. 15. Heike R, Harald S, Matthias M, Katharina K, Viktor S, Bernd W, et al. Accuracy of intraoral and extraoral digital data acquisition for dental restorations. J Appl Oral Sci. 2016;24(1):85–94. 16. Byun C, Kim C, Cho S, Baek SH, Kim G, Kim SG, et al. Endodontic treatment of an anomalous anterior tooth with the aid of a 3-dimensional printed physical tooth model. J Endod. 2015;41(6):961–5. 17. Krastl G, Zehnder MS, Connert T, Weiger R, Kühl S. Guided endodontics: a novel treatment approach for teeth with pulp canal calcification and apical pathology. Dent Traumatol. 2016;32(3):240–6. 18. Shi X, Zhao S, Wang W, Jiang Q, Yang X. Novel navigation technique for the endodontic treatment of a molar with pulp canal calcification and apical pathology. Aust Endod J. 2017;44:66–70. 19. Lin L, Chen MY, Ricucci D, Rosenberg PA. Guided tissue regeneration in periapical surgery. J Endod. 2010;36(4):618–25.

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BMC Oral HealthSpringer Journals

Published: May 10, 2018

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