CE: A.B.; SCS-17-0545; Total nos of Pages: 5; SCS-17-0545 BRIEF CLINICAL STUDIES Corticotomy With a Palatal Bone-Borne Retractor for Correcting Severe Bimaxillary Protrusion Min-Ki Noh, PhD, Young-Jun Kim, PhD,y Kyu-Rhim Chung, PhD, Seong-Hun Kim, PhD, and Gerald Nelson, DDSz Background: This article presents an alternate surgical treatment method to correct a severe anterior protrusion in the adult patient with an extremely thin alveolus. Methods: In the maxilla, a wide linear corticotomy was performed under local anesthesia. Cortical alveolar bone of the upper first bicuspids area was widely removed. Orthopedic force for bony block movement was applied by a palatal bone-borne type retractor supported by skeletal anchorage. Residual extraction space closure was performed by biocreative orthodontics strategy (BOS). In the mandible, an anterior segmental osteotomy (ASO) and extraction of 1st premolars were performed under local anesthesia. Results: In the maxilla, bony block movement followed by the wide linear corticotomy with a palatal bone-borne type retractor was implemented without complications. Remaining extraction space after the bony block movement was closed effectively by BOS. In the mandible, anterior segmental retraction was achieved effectively by ASO. Conclusions: Wide linear corticotomy with a palatal bone-borne type retractor and ASO under local anesthesia can be an effective alternative to orthognathic surgery in adults with protrusion and an extremely thin alveolus. The biocreative strategy also provides a simple and effective method to retract the 6 anterior teeth. movement is heavier than the optimal orthodontic force.6 In previous studies, skeletal anchorage devices such as the C-palatal plate and C-tube performed the role of a reliable and rigid skeletal anchorage for orthopedic force.7– 9 The treatment method is substantial just as much as anchorage requires. In the patient with either thin alveolus or upright position of incisors in maxilla, it is restricted with conventional treatment due to retraction forces directly to the teeth. To overcome this limitation, contractor was established as a reverse concept to distractor by applying backward forces in place of forward forces (Fig. 1). This protocol provides independent en-masse retraction of the anterior teeth without requiring orthodontic appliances on the posterior segments during the retraction. The purpose of this report is to suggest that the bone-borne type retractor after a wide linear corticotomy and a mandibular ASO are an effective treatment option for the severe bimaxillary protrusion with a thin alveolus. METHODS Under the local anesthesia, 1st premolar extraction on both arches and particularly a wide linear corticotomy in the maxilla combine with ASO in the mandible were performed.10 The cortical alveolar bone around the upper first bicuspids was removed linearly as wide as possible within the limit not to damage adjacent roots (Fig. 2A). A palatal bone-borne type retractor was designed to move anterior bony block segment in a posterior direction. This retractor consists of 4 parts: palatal C-implants, expansion screws (Forestadent Co, Pforzheim, Germany), an acrylic body (Forestacryl, Forestadent Co), and a guiding plate. The acrylic resin body consists of an anterior and a posterior part to hold an anterior and a posterior bony segment, respectively. These separated bodies are connected with expansion screws. A palatal bone-borne type retractor was stabilized when the expansion screws were fully opened in order to make Key Words: Anterior segmental osteotomy, biocreative orthodontics strategy, C-implant, palatal bone-borne type retractor, thin alveolus, wide linear corticotomy T o overcome periodontal and skeletal limitations in adult bimaxillary protrusion patients, various surgical techniques such as anterior segmental osteotomy (ASO)1,2 and corticotomy3 have been developed. Chung et al introduced a new type of corticotomyassisted orthodontic treatment called speedy surgical orthodontics, which allows movement of dental segments over a shorter time by using a corticotomy and an orthopedic force for treating severe anterior protrusion in adults.4,5 Orthopedic force for bony block From the Department of Orthodontics, Graduate School, Kyung Hee University, Seoul; yPrivate Practice, Bucheon, Korea; and zDivision of Orthodontics, Department of Orofacial Science, University of California San Francisco, San Francisco, CA. Received March 25, 2017. Accepted for publication August 2, 2017. Address correspondence and reprint requests to Seong-Hun Kim, PhD, Department of Orthodontics, Graduate School, Kyung Hee University, 1 Hoegi-dong, Dongdaemun-gu, Seoul 130-701, Korea; E-mail: firstname.lastname@example.org The authors report no conflicts of interest. Copyright # 2017 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0000000000004057 The Journal of Craniofacial Surgery FIGURE 1. (A) Study model before setup. (B) Study model after setup. After 1st premolars are extracted, anterior segment is retracted to the posterior part. (C, D) Palatal bone-borne type retractor on set-up model. Red-dotted line means wide linear corticotomy line. (E, F) Retractor on the palatal side with guiding plate. Volume 00, Number 00, Month 2017 1 Copyright © 2017 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited. CE: A.B.; SCS-17-0545; Total nos of Pages: 5; SCS-17-0545 Brief Clinical Studies The Journal of Craniofacial Surgery Volume 00, Number 00, Month 2017 year. After anterior bone segment retraction and complementary space closure anchored by C-implant, the finishing stage was performed with full fixed appliances. This treatment mechanics is called biocreative orthodontics strategy (BOS).11 CLINICAL REPORT FIGURE 2. Wide linear corticotomy and palatal bone-borne type retractor application. (A, B) Intraoral photographs of after wide linear corticotomy and 1st bicuspid extraction on maxilla. (C) Removal of guiding plate. (D) Intraoral photograph of after removing both guiding plates. (E, F) Right before screw activation. (G, H) Five days after screw activation: 5 mm closure. it function reversely. A guiding plate was used to lead correct positioning of the retractor during delivery (Fig. 1D-F). An acrylic resin body and a guiding plate were fabricated on the cast model along the surface of in order the palate and 1st, 2nd premolars with 1st molar. After delivery of the retractor, guiding plates that connected with acrylic resin by stainless steel wire were removed (Fig. 2C-D). The retractor is supported by 4 mini-implants bilaterally: 2 on the anterior acrylic pad between the lateral incisors and canines, and the other 2 on posterior pad between the first molars and the second molars. Six partial osseointegration-based C-implants (sand-blasted, large-grit, acid-etched mini-implant; Dentium Co., Seoul, Korea) with a 0.8-mm tube hole were placed palatally, 2 for anterior segment, 1 for posterior segment per side. The next appointment of insertion, they were bonded to the acrylic body with acrylic resin. The retractor was activated by turning an expansion screw in the reverse (closing) direction. Five days later, brackets were placed on the anterior dentition for accomplishment of space closure. In this study, C-implants were used as the only source of anchorage for enmasse retraction of the 6 maxillary anterior teeth.11 Four C-implants were placed bilaterally between the 2nd premolars and the 1st molars in both arches to achieve maximum anchorage for retraction. No brackets or bands were placed on the posterior dentition for 1 2 A 25-year-old woman complained of anterior protrusion. Her protruded lip profile was affected by flat mentolabial sulcus and mentalis hyperactivity. The intraoral examination showed Class III molar and canine relationships on the left and Class I molar and canine relationships on the right, with an anterior openbite and dental midline deviation (Fig. 3A-C). The initial lateral cephalometric analysis showed a skeletal Class II relationship (A point, nasion, B point angle, 5.58) with deficient mandibular length (Fig. 6A). Sagittal images of cone beam computed tomography of incisors demonstrated an extremely thin alveolus around the anteriors. Patients refused the orthognathic surgery, which needs to be under general anesthesia. Thereby surgical approaches under local anesthesia were applied alternatively. ASO and 1st premolars extraction in the mandible, and a wide linear corticotomy around 1st bicuspids area in the maxilla were performed under local anesthesia. A palatal bone-borne type retractor was applied for bony block movement. The patient was instructed to activate both screws 4 quarter turns a day which produces 0.25 mm of bony block movement (Fig. 2E-F). Five days later, activation of expansion screws was suspended (Fig. 2 G-H). Minimally remained extraction space was closed by BOS, which allows independent en-masse retraction of the anterior teeth without brackets or bands on the posterior teeth. C-implants were used as the only source of anchorage (Fig. 4A-I), and terminally finishing stage was performed with full-fixed appliances (Fig. 4J-L). Treatment duration was 2 years. Proper overbite and overjet were obtained (Fig. 5A-C). The result was stable without any periodontal complications. Better facial appearance was obtained. Remarkable retraction of lip posture was achieved. Hyperactivity of mentalis muscle was so relieved that a natural mentolabial fold appeared. The patient’s palatal plane to upper incisor angle was changed from 1108 to 958 during treatment and incisor mandibular plane angle was changed to 38 (pretreatment 1088, post-treatment 1058) (Fig. 6). Post-treatment sagittal images of the cone beam computed tomography were reviewed (Fig. 6D-G). There was no significant negative change in the dentoalveolar status or root length of anterior teeth. Ten years after the completion of treatment, the patient had a stable occlusion and esthetic profile (Figs. 5G-L, 6H-K). DISCUSSION To overcome periodontal and alveolar housing limitations, and extend the achievable range of tooth movement, surgical-assisted tooth movement is needed.6,12 Anterior segmental osteotomy and corticotomy are less invasive techniques than orthognathic surgery, and can be performed under local anesthesia, which reduces the fear of the patient and leads to fewer surgical complications or side effects.3,13 Anterior segmental osteotomy can provide a significant enhancement of the lateral soft tissue profile in bimaxillary protrusive patients who want immediate esthetic improvement.14 Corticotomy can reduce treatment time via the bony block movement and regional accelerating phenomenon.15,16 Corticotomy facilitated segmental movement of alveolar block is possible due to removal of the cortical resistance.3,6 If more segment mobilization was attained by corticotomy, more bony block movement effect could occur.17 In this patient, the corticotomy line was wider than the typical corticotomy line, so bony resistance was sufficiently reduced to facilitate retraction of the bony block. Orthopedic force for bony block movement needs to be heavier than the optimum orthodontic force.6 In this patient, a palatal bone-borne type retractor was used # 2017 Mutaz B. Habal, MD Copyright © 2017 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited. CE: A.B.; SCS-17-0545; Total nos of Pages: 5; SCS-17-0545 The Journal of Craniofacial Surgery Volume 00, Number 00, Month 2017 Brief Clinical Studies FIGURE 3. (A-C) Pretreatment intraoral photographs (age, 25 years 11 months) show anterior openbite, moderate crowding on maxilla and mandible. Set-up models before retraction of anterior part on maxilla and ASO on mandible (D-F) and after retraction of anterior part on maxilla and ASO on mandible (G-I). ASO, anterior segmental osteotomy. to generate the orthopedic force. The heavy force of the expansion screws was transmitted to the perisegmental corticotomy site through anterior and posterior parts of retractor. Because this is not tooth-borne anchorage system, there is no possibility of unwanted tooth movement out of the alveolar bone housing. This type of appliance also has an esthetic advantage during retraction, since it is not visible to the patient’s public. The palatal bone-borne type retractor was supported by 3 palatal mini-implants bilaterally (Fig. 2). There was not sufficient room for placing 1 more mini-implants in the posterior segment. But 1.8 mm-in diameter 9.5 mm sand blasted large grit and acid etched surface-treated C-implants successfully resisted the traction force. These implants were enough to support the orthopedic force in this adult patient. # 2017 Mutaz B. Habal, MD FIGURE 4. Treatment progress intraoral photographs (biocreative orthodontics strategy). (A-C) Beginning of En-masse retraction, 0.016 0.022-in stainless steel utility archwire on both dentitions and 0.25-in, 3.5-oz elastics between hooks and C-implant. (D-F) En-masse retraction, 0.25-in, 3.5-oz elastics, and elastomeric chains between hooks and C-implant. (G-I) Completion of En-masse retraction. (J-L) Finishing stage. After the bony block movement by the retractor, BOS was applied to complete the space closure. It has advantage of not disturbing the posterior teeth.9,18 Retraction time is shortened, since no preliminary alignment of posterior teeth is necessary. The Cimplant holes substitute for multiple posterior fixed appliances. This concept was developed because partially osseointegrated miniimplants (C-implant) can endure multidirectional heavy forces and support orthodontic archwires.11,19,20 3 Copyright © 2017 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited. CE: A.B.; SCS-17-0545; Total nos of Pages: 5; SCS-17-0545 The Journal of Craniofacial Surgery Brief Clinical Studies Volume 00, Number 00, Month 2017 FIGURE 6. Lateral cephalograms. (A) Pretreatment. (B) Right after anterior segmental osteotomy on mandible. (C) Post-treatment. (D-G) Sagittal images of cone beam computed tomography of incisors before treatment show extremely thin alveolus. (H-K) Sagittal images of cone beam computed tomography of incisors 10 years after treatment. There were no significant differences in dentoalveolar changes and root length of anterior teeth. ACKNOWLEDGMENTS The authors thank to Won Lee, Professor and Chair of Department of Dentistry, the Catholic University of Korea Uijungbu St Mary’s Hospital for surgical assistance and Dr Nur Serife Iskenderoglu, Department of Orthodontics, Graduate School, Kyung Hee University for manuscript editing. REFERENCES FIGURE 5. Post-treatment intraoral photographs and panoramic radiograph (age, 28 years, A-F). (G-L) Ten years after treatment. 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Effects of surface treatment on the osseointegration potential of orthodontic mini-implant. Korean J Orthod 2008;38:328–336 5 Copyright © 2017 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.