Mechanical Evaluation of Different Stable Internal Fixation Techniques of Sagittal Osteotomy in Mandibular Advance / Evaluación Mecánica de Diferentes Técnicas de Fijación Interna Estable de Osteotomía Sagital en Avance Mandibular

The mandibular advancements performed in orthognathic surgeries can be stabilized with several techniques when using stable internal fixation. This study aims to comparatively evaluate, in vitro, the mechanical strength in a polyurethane mandibular model for four fixation techniques for sagittal split ramus osteotomy mandibular. 60 samples were divided into 4 groups, with 15 units for each group: group A, group B, group C and group D. Advances of 5 mm were made for each subgroup and fixed with 2.0 mm system plates and monocortical screws in the replicas of human hemimandibles in polyurethane resin. The samples were submitted to mechanical tests of linear loading, being evaluated the peak load and peak deformation. Technique B presented higher peak load (Kgf) and techniques A and B presented higher peak strain (p<0.05). Technique D presented lower peak load and lower peak strain (p<0.05). It is concluded that the study based on the development of new techniques for fixation for sagittal osteotomy of the mandibular ramus is of great importance for the advancement of orthognathic surgery, provided by the technical innovation of more favorable plate models.

Los avances mandibulares realizados en cirugías ortognáticas pueden estabilizarse con varias técnicas cuando se utiliza fijación interna estable. Este estudio tuvo como objetivo evaluar comparativamente, in vitro, la resistencia mecánica en un modelo mandibular de poliuretano para cuatro técnicas de fijación para la osteotomía sagital de la rama mandibular. Se dividieron 60 muestras en 4 grupos, con 15 unidades para cada grupo: grupo A, grupo B, grupo C y grupo D. Se realizaron avances de 5 mm para cada subgrupo y se fijaron con placas de sistema de 2,0 mm y tornillos monocorticales en las réplicas de hemimandíbulas humanas en resina de poliuretano. Las muestras fueron sometidas a pruebas mecánicas de carga lineal, siendo evaluadas la carga máxima y la deformación máxima. La técnica B presentó mayor pico de carga (Kgf) y las técnicas A y B presentaron mayor pico de deformación (p<0,05). La técnica D presentó menor carga máxima y menor tensión máxima (p<0,05). Se concluye que el estudio basado en el desarrollo de nuevas técnicas de fijación para la osteotomía sagital de la rama mandibular es de gran importancia para el avance de la cirugía ortognática, proporcionada por la innovación técnica de modelos de placas más favorables.

Comparação da fragilidade gerada por 3 diferentes osteotomias sagitais de mandíbula: estudo in vitro / Comparison of fragility generated by 3 different sagittal mandible osteotomies: in vitro study / Comparación de la fragilidad generada por 3 osteotomías mandibulares sagitales diferentes: estudio in vitro

A osteotomia sagital bilateral de mandíbula (OSBM) foi publicada por Trauner e Obwegeser em 1957, desde então sofreu várias modificações a fim de diminuir as complicações e tornar o procedimento mais simples e previsível. Sendo assim objetivo do presente trabalho foi avaliar e comparar a fragilidade causada na mandíbula por 3 tipos de OSBM. Para isso, foram realizadas as osteotomias propostas por Trauner e Obwegeser modificada por Hunsuck e Epker (I), a de Sant'Ana (II) e de Wolford (III), em 24 hemimandibulas de poliuretano e foi realizado o ensaio mecânico para gerar a fratura sagital. Os dados foram coletados e tabulados, e obteve como resultado que, a maior quantidade de força máxima aplicada foi observada no grupo III, e a menor quantidade no grupo II; com relação à deflexão, apresentou significância estatística entre o grupo II e grupo III; com relação à rigidez, a maior média, foi encontrada no grupo I. Sendo assim, foi possível concluir que dentro deste modelo de estudo a osteotomia II foi capaz de gerar maior fragilidade à hemimandibula de poliuretano com menor quantidade de força. As OBMD dos grupos I e a III também apresentaram ótimos resultados, entretanto necessitaram mais força para alcançar a fratura... (AU)

The bilateral sagittal split osteotomy of the mandible (BSSO) was published by Trauner and Obwegeser in 1957, since then it has undergone several modifications in order to reduce complications and make the procedure simpler and more predictable. Therefore, the objective of this study was to evaluate and compare the fragility caused in the mandible by 3 types of BSSO. For this, the osteotomies proposed by Trauner and Obwegeser modified by Hunsuck and Epker (I), Sant'Ana (II) and Wolford (III) were performed on 24 polyuretha ne hemimandibles, a mechanical test to generate the sagittal fracture. Data were collected and tabulated, and the result was that, the highest amount of maximum force applied was observed in group III, and the lowest amount in group II; with regard to deflection, it was statistically significant between group II and group III; with regard to stiffness, the highest average was found in group I. Therefore, it was possible to conclude that within this study model, osteotomy II was able to generate greater fragility to the polyurethane hemimandible with less force. The BSSO of the groups I and III also showed excelent results, however they required more force to reach the fracture... (AU)

La osteotomía sagital bilateral de la mandíbula (OSBM) fue publicada por Trauner y Obwegeser en 1957, desde entonces ha sufrido varias modificaciones con el fin de reducir las complicaciones y hacer el procedimiento más simple y predecible. Por lo tanto, el objetivo de este estudio fue evaluar y comparar la fragilidad causada en la mandíbula por 3 tipos de OSBM. Para eso, se realizaron las osteotomías propuestas por Trauner y Obwegeser modificadas por Hunsuck y Epker (I), Sant'Ana (II) y Wolford (III) en 24 hemimandíbulas de poliuretano y se realizó un ensayo mecánico para generar la fractura sagital. Los datos fueron recolectados y tabulados, obteniendo como resultado que, la mayor cantidad de fuerza máxima aplicada se observó en el grupo III, y la menor cantidad en el grupo II; en cuanto a la deflexión, fue estadísticamente significativa entre el grupo II y el grupo III; en cuanto a la rigidez, la media más alta se encontró en el grupo I. Por lo tanto, se pudo concluir que, dentro de este modelo de estudio, la osteotomía II logró generar mayor fragilidad a la hemimandíbula de poliuretano con menor fuerza. El OSBM de los grupos I y III también mostró excelentes resultados, pero requirieron mayor fuerza para llegar a la fractura... (AU)

Application and development of orthognathic surgery in treatment of syndromic craniosynostosis / 中国修复重建外科杂志

OBJECTIVE@#To summarize the application and recent development of orthognathic surgery in treating syndromic craniosynostosis.@*METHODS@#The related literature at home and abroad in recent years was extensively reviewed, and the indications, routine procedures, and protocols of orthognathic surgery in the treatment of syndromic craniosynostosis were summarized and analyzed.@*RESULTS@#Craniosynostosis is a common congenital craniofacial malformation. Syndromic craniosynostosis usually involves premature fusion of multiple cranial sutures and is associated with other deformities. Orthognathic surgery is the necessary and effective means to improve the midfacial hypoplasia and malocclusion. Le Fort I osteotomy combined with sagittal split ramus osteotomy are the common surgical options. Orthognathic surgery should combine with craniofacial surgery and neurosurgery, and a comprehensive long-term evaluation should be conducted to determine the best treatment plan.@*CONCLUSION@#Orthognathic surgery plays an important role in the comprehensive diagnosis and treatment of syndromic craniosynostosis. The development of digital technology will further promote the application and development of orthognathic surgery in the treatment of syndromic craniosynostosis.

Establishment of a three-dimensional coordinate system for measuring the recurrence rate after orthognathic surgery and evaluation and analysis of the degree of recurrence / 口腔疾病防治

Objective@# To establish a three-dimensional coordinate system that can accurately measure the recurrence rate after orthognathic surgery, and evaluate and analyze the degree of recurrence.@*Methods @#Data from patients who underwent orthognathic surgery in a hospital were selected to reconstruct three-dimensional images with spiral CT. The two researchers used the multiplane assisted positioning method to fix the points three times and screened them using intra-andintreclass correlation coefficients (ICC). Reproducible and accurate landmark points were drawn to establish different coordinate systems and calculate the facial asymmetry index (AI) to determine the coordinate system with the best mid-sagittal plane symmetry. This coordinate system and lateral radiographs were used to separately measure the recurrence rate, and evaluate and analyze the three-dimensional recurrence degree of orthognathic surgery.@*Results @#Ten landmark points that may be repeatedly fixed were obtained, including N (nasion), K (K point), ANS(anterior nasal spine), PNS (posterior nasal spine), Ptm(pterygomaxillary fissure), Gn (gnathion), IZ(IZ point), MZ (MZ point), Ms (mastoideale), Cor (coronion) and and Go (gonion). Three coordinate systems were established, and the most suitable coordinate system was the upper edge point of the left infraorbital foramen. The inner upper edge of the right infraorbital foramen and both sides of the midpoint of the ear points constituted the horizontal plane (HP), which passed through the outermost point of the left zygomatic frontal suture and the outermost point of the right zygomatic frontal suture and was perpendicular to the horizontal plane to constitute the coronal plane (CP). It was perpendicular to the two planes to form a sagittal plane (SP). Two-dimensional and three-dimensional measurements of recurrence were performed on 112 patients, and new three-dimensional recurrence evaluation results were obtained. Less than 40% had low recurrence, 40% to 61% had moderate recurrence, and greater than 61% had high recurrence.@*Conclusion@#This study established a three-dimensional coordinate system suitable for measuring the recurrence rate after orthognathic surgery, obtained a new three-dimensional recurrence evaluation result, and provided a clinical experimental basis for evaluating the effect of orthognathic surgery and improving stability.

Estabilidad del tratamiento ortodóncico-quirúrgico de avance mandibular mediante osteotomía sagital bilateral de rama mandibular en pacientes clase II. Revisión narrativa / Stability of the orthodontic-surgical treatment of mandibular advancement through bilateral sagittal split osteotomy in class II patients. Narrative review

RESUMEN: Introducción: La anomalía esqueletal clase II posee un 16 a 22,5% de prevalencia mundial. Cuando estos pacientes se someten al avance mandibular mediante osteotomía sagital de rama mandibular pueden presentar un grado de inestabilidad postoperatoria evidenciándose como recidiva de éste. Objetivo: Describir la estabilidad del avance mandibular mediante osteotomía sagital bilateral de rama mandibular en pacientes clase II esqueletal. Material y método: Se realizó una búsqueda electrónica en las bases de datos PubMed, EBSCO, The Cochrane Library, Tripdatabase y Scopus mediante las palabras clave "mandibular stability", "skeletal stability", "mandibular advancement", "sagittal split osteotomy", "sagittal split ramus osteotomy", "class II", "class III" y "distraction osteogenesis", relacionadas entre sí con los términos booleanos AND, OR y NOT. También se incluyeron los términos MeSH "mandibular advancement" y "Sagittal Split Ramus Osteotomy". Paralelamente se realizó una búsqueda manual en las revistas AJODO, BJOMS, JOMS y EJO. Resultados y discusión: Se seleccionaron 29 artículos: 24 estudios observacionales analíticos, 2 revisiones sistemáticas y 3 ensayos clínicos aleatorizados. El avance mandibular mediante osteotomía sagital de rama mandibular es estable. No obstante, se debe tener en cuenta la existencia de múltiples factores pre e intraquirúrgicos que podrían generar recidiva del tratamiento.

ABSTRACT: Introduction: The class II skeletal anomaly has a 16-22,5% prevalence worldwide. When class II patients undergo mandibular advancement through Bilateral Sagittal Split Osteotomy (BSSO), they can present a postoperative instability, evidenced as a relapse. Objective: To describe the stability of mandibular advancement through BSSO in skeletal class II patients. Materials and method: An electronic search was performed in the databases PubMed, EBSCO, The Cochrane Library, Tripdatabase and Scopus using the keywords "mandibular stability", "skeletal stability", "mandibular advancement", "sagittal split osteotomy", "sagittal split ramus osteotomy", "class II", "class III" and "distraction osteogenesis", related to each other with the Boolean terms AND, OR and NOT. Also "mandibular advancement" and "Sagittal Split Ramus Osteotomy" MeSH terms were included. In parallel, a manual search in the journals AJODO, BJOMS, JOMS and EJO was performed. Results and discussion: 29 articles were selected: 24 analytic observational studies, 2 systematic reviews and 3 randomized clinical trials. Mandibular advancement through BSSO is stable. However, multiple pre and intraoperative factors that could cause a treatment relapse must be taken into account.

Evaluation of the Different Methods for Fixation of Sagittal Ramus Split Osteotomy of the Mandibular Ramus in Relation to Stability for Mandibular Advancement: A Systematic Review

Aims: The purpose of this study was to perform a systematic review of the literature on the different fixation methods available for sagittal ramus split osteotomyassociated with mandibular advancement testedin vitroto evaluate stability of each method.Study Design:Systematic review.Methodology:Following the PRISMA model for systematic reviews, a query was made in the PubMed, Bireme and Cochrane Library databases, identifying articles that reported the different fixation methods for sagittal ramus split osteotomyfor mandibular advancement. Results:A total of 352 articles were identified, 11 papers of which, after evaluation in relation to the inclusion and exclusion criteria, were systematically reviewed.

Three-dimensional changes in condylar position in skeletal class Ⅲ patients with mandibular deviation after bilateral sagittal split ramus osteotomy / 中华口腔医学杂志

Objective@#To investigage the three-dimensional changes in condylar position after bilateral sagittal split ramus osteotomy (BSSRO) in skeletal class Ⅲpatients with mandibular deviation using cone-beam CT (CBCT).@*Methods@#Twenty-five skeletal class Ⅲ patients with mandibular deviation were included. The patients (12 males and 13 females, aged 19-25 years, average age 22.4 years) were treated in the Department of Orthodontics, Affiliated Stomatological Hospital, Nanchang University from October 2013 to March 2017. The patients were divided into T1, T2 and T3 groups (T1 group: CBCT taken within 1 week before operation; T2 group: CBCT taken within 1 week after operation; T3 group: CBCT taken 6-8 months after surgery). Three sets of image data of condyles on both sides (deviation side and contralateral side) were obtained. After the DICOM data collection, the software of Mimics 17.0 was used to perform three-dimensional reconstruction and condylar position measurements: the distance from the condylar top (CoT) to the standard horizontal plane (SHP), the middle sagittal plane (MSP) and the sella coronal plane (SCP) (CoT-SHP, CoT-MSP, CoT-SCP); the distance from the condylar center (CoC) to SHP, MSP and SCP (CoC-SHP, CoC-MSP, CoC-SCP); the angle from the condyle cella plane (CCP) to SHP, MSP and SCP (CCP-SHP, CCP-MSP, CCP-SCP); the angle from the condyle sagittal plane (CSP) to SHP, MSP and SCP (CSP-SHP, CSP-MSP, CSP-SCP) and the distance of the anterior, superior, posterior, medial, central and lateral joint space. One-way ANOVA and LSD-t test were used to compare the changes in condylar position at different periods (T1, T2, and T3).@*Results@#Within 1 week before operation on the deviation side, CoT-SHP [(2.5±1.3) mm], CSP-MSP (41.2°±8.4°) and the posterior joint space [(2.0±0.6) mm] were obviously increased (P<0.05), and CoT-SCP [(9.1±3.3) mm], CCP-MSP (78.2°±5.2°) were decreased significantly (P<0.05); on the contralateral side, CoT-MSP [(50.4±3.1) mm], CCP-MSP (80.6°±6.0°), the anterior joint space [(2.2±0.6) mm] and the medial joint space [(2.6±0.6) mm] were obviously increased (P<0.05), and CCP-SCP (11.4°±8.8°) were decreased significantly (P<0.05). Six to eight months after surgery, CoT-SHP [(2.2±1.0) mm] and the posterior joint space [(1.9±0.5) mm] on deviation side and CoT-SCP [(8.4±2.8) mm] on the contralateral side were increased significantly (P<0.05). No significant difference was found in other measurements (P>0.05).@*Conclusions@#The condylar position in skeletal class Ⅲ patients with mandibular deviation was asymmetrical. Within 1 week after the operation of BSSRO, the condyle on the deviation side was moved forward, downward and inward. Meanwhile, the condyle on the contralateral side was moved backward and outward. Six to eight months after surgery, the condylar position on both sides was gradually restored to the pre-operative condylar position.

Concepts, protocol, variations and current trends in surgery first orthognathic approach: a literature review

ABSTRACT In the current era of expedited orthodontics, among many clinicians, tertiary care hospitals and patients, surgery first orthognathic approach (SFOA) has gained popularity. The advantages of SFOA (face first approach) are the reduced overall treatment duration and the early improvement in facial esthetics. In SFOA, the absence of a presurgical phase allows surgery to be performed first, followed by comprehensive orthodontic treatment to achieve the desired occlusion. The basic concepts of surgery early, surgery last, SFOA and Sendai SFOA technique along with its variations are reviewed in the present article. The recent advancement in SFOA in the context of preoperative preparation, surgical procedures and post-surgical orthodontics with pertinent literature survey are also discussed.

RESUMO Na presente era da Ortodontia de resultados acelerados, a cirurgia ortognática com benefício antecipado (COBA) ganhou popularidade entre muitos clínicos, hospitais terciários e pacientes. A vantagem da COBA é a redução da duração total do tratamento, juntamente com a melhora precoce da estética facial. Na COBA, a ausência de uma fase pré-cirúrgica permite que a cirurgia seja realizada antes e, só então, venha o tratamento ortodôntico abrangente para se alcançar a oclusão desejada. Os conceitos básicos de cirurgia primeiro, cirurgia por último, COBA e a técnica COBA de Sendai, bem como suas variações, são aqui revistos. Também são discutidos no presente artigo, junto com a revisão da literatura pertinente, os recentes avanços da COBA no contexto do preparo pré-cirúrgico, dos procedimentos cirúrgicos e da Ortodontia pós-cirúrgica.

The effect of botulinum toxin-A injection into the masseter muscles on prevention of plate fracture and post-operative relapse in patients receiving orthognathic surgery / 대한악안면성형재건외과학회지

BACKGROUND: Botulinum toxin-A (BTX-A) injection into muscle reduces muscular power and may prevent post-operative complication after orthognathic surgery. The purpose of this study was (1) to evaluate BTX-A injection into the masseter muscle on the prevention of plate fracture and (2) to compare post-operative relapse between the BTX-A injection group and the no injection group. METHODS: Sixteen patients were included in this study. Eight patients received BTX-A injection bilaterally, and eight patients served as control. All patients received bilateral sagittal split ramus osteotomy for the mandibular setback and additional surgery, such as LeFort I osteotomy or genioplasty. Post-operative plate fracture was recorded. SNB angle, mandibular plane angle, and gonial angle were used for post-operative relapse. RESULTS: Total number of fractured plates in patients was 2 out of 16 plates in the BTX-A injection group and that was 8 out of 16 plates in the no treatment group (P = 0.031). However, there were no significant differences in post-operative changes in SNB angle, mandibular plane angle, and gonial angle between groups (P > 0.05). CONCLUSIONS: BTX-A injection into the masseter muscle could reduce the incidence of plate fracture.

Surgery-first approach for Angle class Ⅲ malocclusion: clinical retrospective analysis of 185 cases / 中华整形外科杂志

Objective@#The purpose of this study was to explore the surgery-first approach in sequential combined orthodontic-orthognathic treatment to shorten total treatment duration and improve the clinical outcome.@*Methods@#This study included 185 patients with Angle classⅢ malocclusion. The patients were divided into 3 different types according to cephalometry analyses and facial features. ①Type Ⅰ: mandibular prognathism or asymmetry mandibular prognathism; ②Type Ⅱ: mandibular prognathism and maxillary retrusion; ③ Type Ⅲ: mild Angle′s Class Ⅲ malocclusion, cross bite in anterior teeth, or normal overlap and overbite relation with midfacial hypoplasia. All of patients received surgery first approach therapy. The surgical procedures were chosen according to different malformation types. Type Ⅰ was treated with the sagittal split ramus osteotomy (SSRO). Type Ⅱ was treated by Le Fort Ⅰmaxillary osteotomy combined with SSRO. Type Ⅲ underwent anterior subapical osteotomy combined pyriform aperture augmentation with biomaterials as well as maxillary anterior orthodontics. All patients received postoperative rapid orthodontic treatment for 6-12 month after 2 weeks of operation. Using the straight arch wire techniques and the class Ⅲ intermaxillary traction, we removed the overcrowding upper and lower teeth, the compensatory axial tilt of teeth, and the deviation of the dental arch and maintained the neutral relationship of the molar. The mandible Hawley retaining devices were used during the maintaining stage.@*Results@#The cases in study acquired satisfactory clinical outcome, which included the shortened overall treatment duration, the significantly improved facial features, the corrected occlusion relationship, and the restored function of mastication and temporomandibular joint. There were some complications as follows: intraoperative fracture (6 cases, 3.24%), the inferior alveolar nerve bundle injury (2 cases, 1.1%), and temporary open-bite that diminished by inter-maxillary elastic distraction one month after operation (19 cases, 10%). All cases in this study accepted postoperative orthodontic treatment. Follow-up time ranged from 6 months to 5 years. The cephalometric analysis results of 126 cases who had complete image data and over 6 months of follow-up showed that hard and soft tissue indexes were restored to normal range after combined orthognathic-orthodontic treatment. The stability of the maxillary and occlusive relationship of SFA(surgery-first approach) was similar to that of the COS(conventional orthodontics-first system) [relapse ratio=(T2-T1)/(T1-T0)×100%]. Over six months of follow-up , SNB and ANB showed that the average relapse ratio were 22% and 19.8%, whereas the relapse angle are less than 2°.@*Conclusions@#The Surgery-first approach could be used to treat most patients with Angle skeletal Class Ⅲ malocclusion, but the indications and the surgical procedures should be noticed and chosen.

Anatomical position of the mandibular canal in relation to the buccal cortical bone: relevance to sagittal split osteotomy

OBJECTIVES: Classification of the degree of postoperative nerve damage according to contact with the mandibular canal and buccal cortical bone has been studied, but there is a lack of research on the difference in postoperative courses according to contact with buccal cortical bone. In this study, we divided patients into groups according to contact between the mandibular canal and the buccal cortical bone, and we compared the position of the mandibular canal in the second and first molar areas. MATERIALS AND METHODS: Class III patients who visited the Dankook University Dental Hospital were included in this study. The following measurements were made at the second and first molar positions: (1) length between the outer margin of the mandibular canal and the buccal cortical margin (a); (2) mandibular thickness at the same level (b); (3) Buccolingual ratio=(a)/(b)×100; and (4) length between the inferior margin of the mandibular canal and the inferior cortical margin. RESULTS: The distances from the canal to the buccal bone and from the canal to the inferior bone and mandibular thickness were significantly larger in Group II than in Group I. The buccolingual ratio of the canal was larger in Group II in the second molar region. CONCLUSION: If mandibular canal is in contact with the buccal cortical bone, the canal will run closer to the buccal bone and the inferior border of the mandible in the second and first molar regions.

New Treatment in Facial Nerve Palsy Caused by Sagittal Split Ramus Osteotomy of Mandible

A 25-years-old woman with mandibular prognathism underwent a mandibular setback by way of mandibular sagittal split ramus osteotomy (MSSRO). After 2 days of operation, she developed difficulty of closing her right eye. The blink reflex test and motor nerve conduction study of the right orbicularis oris muscle were revealed right facial neuropathy of unknown origin and House-Brackmann facial nerve grading system (HBFNGS) grade V. For treatment, we initially prescribed oral prednisolone and nimodipine including physical therapy. The samples consisted of 11 facial nerve palsy patients caused by MSSRO and were analysed about onset of facial nerve palsy, postoperative HBFNGS, final HBFNGS, treatment method and recovery time. At 10 weeks of treatment of nimodipine, she had completely regained normal function (HBFNGS grade I) of the right facial nerve. The clinical results lead to assume a fast recovery of facial nerve function by the nimodipine medication, whereas average time of recovery is 16.32 weeks in references. Despite of the limited one patient treated, the result was very promising with respect to a faster recovery of the facial nerve function. Considering the use of nimodipine treatment for peripheral facial nerve palsy following a surgical approach with an anatomically preserved nerve can be recommended.

Mechanical evaluation of the use of conventional and locking miniplate/screw systems used in sagittal split ramus osteotomy

OBJECTIVES: The aim of this study was to compare the mechanical resistance of four different osteosyntheses modeled in two different sagittal split ramus osteotomy (SSRO) designs and to determine the linear loading in a universal testing machine. MATERIALS AND METHODS: An in vitro experiment was conducted with 40 polyurethane hemimandibles. The samples were divided into two groups based on osteotomy design; Group I, right angles between osteotomies and Group II, no right angles between osteotomies. In each group, the hemimandibles were distributed into four subgroups according to the osteosynthesis method, using one 4-hole 2.0 mm conventional or locking plate, with or without one bicortical screw with a length of 12.0 mm (hybrid technique). Each subgroup contained five samples and was subjected to a linear loading test in a universal testing machine. RESULTS: The peak load and peak displacement were compared for statistical significance using PASW Statistics 18.0 (IBM Co., USA). In general, there was no difference between the peak load and peak displacement related to osteotomy design. However, when the subgroups were compared, the osteotomy without right angles offered higher mechanical resistance when one conventional or locking 2.0 mm plate was used. One locking plate with one bicortical screw showed higher mechanical resistance (162.72±42.55 N), and these results were statistically significantly compared to one conventional plate with monocortical screws (P=0.016) and one locking plate with monocortical screws (P=0.012). The difference in peak displacement was not statistically significant based on osteotomy design or internal fixation system configuration. CONCLUSION: The placement of one bicortical screw in the distal region promoted better stabilization of SSRO. The osteotomy design did not influence the mechanical behavior of SSRO when the hybrid technique was applied.

The Effect of a Condylar Repositioning Plate on Condylar Position and Relapse in Two-Jaw Surgery

BACKGROUND: Numerous condylar repositioning methods have been reported. However, most of them are 2-dimensional or are complex procedures that require a longer operation time and a highly trained surgeon. This study aims to introduce a new technique using a condylar repositioning plate and a centric relation splint to achieve a centric relationship. METHODS: We evaluated 387 patients who had undergone surgery for skeletal jaw deformities. During the operation, a centric relation splint, intermediate splint, final centric occlusion splint, and condylar repositioning plate along with an L-type mini-plate for LeFort I osteotomy or a bicortical screw for bilateral sagittal split ramus osteotomy were utilized for rigid fixation. The evaluation included: a physical examination to detect preoperative and postoperative temporomandibular joint dysfunction, 3-dimensional computed tomography and oblique transcranial temporomandibular joint radiography to measure 3-dimensional condylar head movement, and posteroanterior and lateral cephalometric radiography to measure the preoperative and postoperative movement of the bony segment and relapse rate. RESULTS: A 0.3% relapse rate was observed in the coronal plane, and a 2.8% relapse rate in the sagittal plane, which is indistinguishable from the dental relapse rate in orthodontic treatment. The condylar repositioning plate could not fully prevent movement of the condylar head, but the relapse rate was minimal, implying that the movement of the condylar head was within tolerable limits. CONCLUSIONS: Our condylar repositioning method using a centric relation splint and mini-plate in orthognathic surgery was found to be simple and effective for patients suffering from skeletal jaw deformities.

Enucleation of large keratocystic odontogenic tumor at mandible via unilateral sagittal split osteotomy: a report of three cases

Keratocystic odontogenic tumor (KCOT) is a common benign tumor of osseous lesions in dental and maxillofacial practice. We describe three cases of large KCOT located in the posterior part of the mandible extending to the angle and ramus region, which were enucleated via sagittal split osteotomy (SSO) of the mandible. There are cases in which a conventional enucleation procedure does not ensure complete excision of the entire lesion without damage to vital structures like the inferior alveolar nerve. In such cases, a SSO approach could be a better choice than conventional methods. The purpose of this article is to describe our experience using unilateral mandibular SSO for removal of a KCOT from the mandible.

Treatment of osteomyelitis in the rear area of the lingula of the mandible using sagittal split ramus osteotomy: a case report

Osteomyelitis is classified into three groups according to its origin: osteomyelitis that originates from the blood supply, osteomyelitis related to bone disease or vascular disease, and osteomyelitis related to a local infection of dental or non-dental origin. The present case involved osteomyelitis related to a local infection of dental origin and was located in the rear area of the lingula of the mandible. We decided to use sagittal split ramus osteotomy to access the osteomyelitis area. Under general anesthesia, we successfully performed surgical sequestrectomy and curettage via sagittal split ramus osteotomy.

Unilateral intraoral vertical ramus osteotomy and sagittal split ramus osteotomy for the treatment of asymmetric mandibles

In surgery for facial asymmetry, mandibles can be classified into two types, rotational and translational, according to the required mandibular movements for surgery. During surgery for rotational mandibular asymmetry, a bilateral sagittal split ramus osteotomy (BSSRO) may cause a large bone gap between the proximal and distal segments as well as condylar displacement, resulting in a relapse of the temporomandibular joint disorder, especially in severe cases. The intraoral vertical ramus osteotomy has an advantage, in this respect, because it causes less rotational displacement of the proximal segment on the deviated side and even displaced or rotated condylar segments may return to their original physiologic position. Unilateral intraoral vertical ramus osteotomy (UIVRO) on the short side combined with contralateral SSRO was devised as an alternative technique to resolve the spatial problems caused by conventional SSRO in cases of severe rotational asymmetry. A series of three cases were treated with the previously suggested protocol and the follow-up period was analyzed. In serial cases, UIVRO combined with contralateral SSRO may avoid mediolateral flaring of the bone segments and condylar dislocation, and result in improved condition of the temporomandibular joint. UIVRO combined with contralateral SSRO is expected to be a useful technique for the treatment of rotational mandibular asymmetry.

Bone and Soft Tissue Changes after Two-Jaw Surgery in Cleft Patients

BACKGROUND: Orthognathic surgery is required in 25% to 35% of patients with a cleft lip and palate, for whom functional recovery and aesthetic improvement after surgery are important. The aim of this study was to examine maxillary and mandibular changes, along with concomitant soft tissue changes, in cleft patients who underwent LeFort I osteotomy and sagittal split ramus osteotomy (two-jaw surgery). METHODS: Twenty-eight cleft patients who underwent two-jaw surgery between August 2008 and November 2013 were included. Cephalometric analysis was conducted before and after surgery. Preoperative and postoperative measurements of the bone and soft tissue were compared. RESULTS: The mean horizontal advancement of the maxilla (point A) was 6.12 mm, while that of the mandible (point B) was -5.19 mm. The mean point A-nasion-point B angle was -4.1degrees before surgery, and increased to 2.5degrees after surgery. The mean nasolabial angle was 72.7degrees before surgery, and increased to 88.7degrees after surgery. The mean minimal distance between Rickett's E-line and the upper lip was 6.52 mm before surgery and 1.81 mm after surgery. The ratio of soft tissue change to bone change was 0.55 between point A and point A' and 0.93 between point B and point B'. CONCLUSIONS: Patients with cleft lip and palate who underwent two-jaw surgery showed optimal soft tissue changes. The position of the soft tissue (point A') was shifted by a distance equal to 55% of the change in the maxillary bone. Therefore, bone surgery without soft tissue correction can achieve good aesthetic results.

Stability of unilateral sagittal split ramus osteotomy for correction of facial asymmetry: long-term case series and literature review

Bilateral sagittal split ramus osteotomy is considered a standard technique in mandibular orthognathic surgeries to reduce unexpected bilateral stress in the temporomandibular joints. Unilateral sagittal split ramus osteotomy (USSO) was recently introduced to correct facial asymmetry caused by asymmetric mandibular prognathism and has shown favorable outcomes. If unilateral surgery could guarantee long-term postoperative stability as well as favorable results, operation time and the incidence of postoperative complications could be reduced compared to those in bilateral surgery. This report highlights three consecutive cases with long-term follow-up in which USSO was used to correct asymmetric mandibular prognathism. Long-term postoperative changes in the condylar contour and ramus and condylar head length were analyzed using routine radiography and computed tomography. In addition, prior USSO studies were reviewed to outline clear criteria for applying this technique. In conclusion, patients showing functional-type asymmetry with predicted unilateral mandibular movement of less than 7 mm can be considered suitable candidates for USSO-based correction of asymmetric mandibular prognathism with or without maxillary arch surgeries.

An in vitro comparison between two different designs of sagittal split ramus osteotomy

OBJECTIVES: To evaluate the influence of the type of osteotomy in the inferior aspect of the mandible on the mechanical performance. MATERIALS AND METHODS: The study was performed on 20 polyurethane hemimandibles. A sagittal split ramus osteotomy (SSRO) was designed in 10 hemimandibles (group 1) with a vertical osteotomy in the buccal side (second molar level) and final osteotomy was performed horizontally on the lingual aspect, while the mandible body osteotomy was finalized as a straight osteotomy in the basilar area, perpendicular to the body. For group 2, the same osteotomy technique was used, but an oblique osteotomy was done in the basilar aspect of the mandibular body, forming continuity with the sagittal cut in the basilar area. Using a surgical guide, osteosynthesis was performed with bicortical screws using an inverted L scheme. In both groups vertical compression tests were performed with a linear load of 1 mm/min on the central fossa of the first molar and tests were done with models made from photoelastic resin. Data were analyzed using Student's t-test, establishing a statistical significance when P <0.05. RESULTS: A statistical difference was not observed in the maximum displacements obtained in the two osteotomies (P <0.05). In the extensiometric analysis, statistically significant differences were identified only in the middle screw of the fixation. The photoelastic resin models showed force dissipation towards the inferior aspect of the mandible in both SSRO models. CONCLUSION: We found that osteotomy of the inferior aspect did not influence the mechanical performance for osteosynthesis with an inverted L system.