Magister Chirurgiae Dentium - MChD / Aim: The aim of the study was to investigate whether a correlation exists between the intra- operative position of the Inferior Alveolar Nerve (IAN) and the nerve position as noted on a pre-operative Cone Beam Computer Tomography (CBCT) scan in patients requiring Bilateral Sagittal Split Osteotomy (BSSO) of the mandible. Introduction: The BSSO of the mandible is of fundamental importance in the correction of dental facial deformities. The main post-operative complication of a BSSO of the mandible is Neurosensory Impairment (NSI). To avoid possible NSI it is important to have as much pre- operative information as possible. In this regard, pre-operative CBCT scans can provide the surgeon with an important assessment of the mandibular canal. This information on the buccolingual, superior and inferior position of the canal, especially in the region of the planned osteotomy, could help the surgical team to avoid IAN injury. Materials and Methods: This study correlates the pre-operative position of the IAN as indicated on a CBCT scan with the intra-operative IAN position in patients requiring BSSO of the mandible. Ten standardised cases were included in a prospective case series where twenty mandibular sides were assessed. Results: The variables assessed in this study were location of the nerve, age, sex, type of movement and side of mandible operated on. It was found that only the distance between the Inferior Alveolar Canal (IAC) and the lower border of the mandible are predictive of whether the IAN will be attached to - or free from - the proximal segment of the mandible. Conclusion: From the study it can be concluded that a CBCT scan is a useful and reliable modality in the pre-operative evaluation of patients undergoing BSSO especially with regard to the assessment and mapping of the mandibular canal.

Problem: Third molar removal in sagittal split osteotomies(SSOs) is recommended by some authors at least 6 months preoperatively to prevent unfavorable fractures. Others authors suggest concomitant removal. The purpose of this study was to investigate the effect of third molars during SSOs. Methods: A prospective study of 677 SSOs was conducted. GroupI consisted of 331 SSOs and third molar removal. GroupII consisted of 346 SSOs without third molar. Intraoperative and postoperative evaluations were recorded. Results: The overall rate of unfavorable fractures was 3.1%, with incidences of 2.4% in GroupI, compared to 3.8% in GroupII(P=0.3). The rate of IAN entrapment was lower in GroupI(37.2%) than in GroupII(46.5%;P=0.01). Third molars increased procedural time by 1.7 minutes. Neurosensory deficits were higher in GroupII. Conclusion: Removal of third molars during SSOs is not associated with increased incidence of unfavorable fractures. Their presence decreases IAN entrapment, improve neurosensory recovery, but slightly increases operating time.

Orientador: Marisa Aparecida Cabrini Gabrielli / Resumo: Este estudo avaliou o padrão da separação da osteotomia sagital do ramo mandibular, sob o aspecto lingual e a influência da espessura óssea correlacionando a esse padrão. Para tanto, foram selecionadas tomografias pré e pós-operatórias de 31 pacientes com deformidade dento-esquelética facial que haviam sido submetidos a tratamento ortodôntico-cirúrgico para correção de deformidade facial dento-esquelética. As tomografias foram analisadas utilizando o software Dolphin 3D 11.8. Foram avaliadas 62 osteotomias sagitais do ramo mandibular (OSRM). Nos exames tomográficos pré-operatórios foram consideradas 4 medidas de espessura no sentido vestíbulo lingual, em áreas pré determinadas da osteotomia: Região A - 1,5mm acima da língula mandibular, Região B - 1mm distante da borda anterior de ramo (Região A e B na altura da osteotomia medial), Região C - 5mm distalmente ao segundo molar e 5mm a partir da borda superior (região retromolar) Região D - região de entre as raízes distal e mesial do 1º e 2º molares inferiores, distando 5 mm da base inferior da mandíbula. Nos exames pós-operatórios, foi analisado o padrão de fratura gerada, classificado em padrão I, II, III ou IV, conforme classificação de Plooij et al. Os dados coletados foram analisados pelo teste estatístico de Kruskal-Wallis seguido do pós-teste de Dunn. Foram encontradas 35 fraturas com padrão tipo I; 01 fratura padrão tipo II; 19 do padrão tipo III e 07 fraturas de padrão tipo IV. O padrão I obteve as maiores médias de es... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This study evaluates the split pattern after sagittal split ramus osteotomy and its correlation with the bone thickness. Pre and postoperative computed tomographies of 31 patients submitted to orthognathic surgery for corrections of dentofacial deformities were used in the study. Dicom images were analyzed using the software Dolphin 3D 11.8. In the preoperative tomographies 4 thickness measurements were considered: A - 1.5 mm above the lingula. B - 1mm from the anterior border of the ramus (A and B points at the height of the medial osteotomy cut). C - 5mm distally to the second molar and 5mm from the upper border of the mandible (retromolar region) D - In the region between the mesial and distal roots of the first and second mandibular molars. In the postoperative tomographies the exams were analyzed and classified according to the fracture pattern described in the literature, where I (true Hunsuk), II (posterior cortical of the branch), III (through the mandibular canal) and IV (bad split). The data were analyzed by the Kruskal-Wallis test followed by the Dunn post-test. Results showed 35 type I fractures, 01 type II fracture, 19 type III fractures and 07 type IV fractures. Type I presented the highest thickness average values for the four considered measurements, whereas type IV presented the lowest values for all measurements. The variable bone thickness was statistically significant only for point A, when the types I and IV were compared. Results allowed to conclude that... (Complete abstract click electronic access below) / Mestre

Orientador: Marisa Aparecida Cabrini Gabrielli / Resumo: Considerando a variável anatomia como um possível fator de risco para o desenvolvimento de fraturas indesejadas após a osteotomia sagital do ramo mandibular (OSRM), este estudo avaliou a influência da espessura óssea sob o padrão de fratura entre os seguimentos proximal (contendo o côndilo) e distal (contendo o processo alveolar) após a OSRM. Para tanto, foram selecionadas tomografias pré e pós-operatórias de 31 pacientes (62 OSRM) com deformidade dento-esquelética-facial com tratamento ortodôntico-cirúrgico prévio. As tomografias foram analisadas utilizando o software Dolphin 3D 11.8. Nos exames pré-operatórios considerou-se 4 medidas da espessura óssea no sentido vestíbulo-lingual, em áreas pré determinadas da OSRM: Região A - 1,5 milímetros (mm) acima da língula mandibular, Região B - 1mm distante da borda anterior de ramo (Região A e B na altura da osteotomia medial), Região C - 5mm distalmente ao segundo molar e 5mm a partir da borda superior (região retromolar) Região D - região de entre as raízes distal e mesial do 1º e 2º molares inferiores, distando 6 mm da base inferior da mandíbula. Nos exames pós-operatórios, analisou-se o padrão de fratura gerado, classificando-o em I (Hunsuck verdadeiro), II (cortical posterior), III (através do canal mandibular) ou IV(fratura indesejada), conforme classificação de Plooij et al. Após teste de normalidade, os dados foram analisados pelo teste estatístico não paramétrico de Kruskal-Wallis seguido do pós-teste de Dunn. Encontrou-se... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Considering the variable anatomy as a possible risk factor for the development of undesirable fractures after bilateral sagittal split osteotomy (BSSO). This study evaluates the split pattern after BSSO and its correlation with the bone thickness. Pre and postoperative computed tomographies of 31 patients (62 BSSO) submitted to orthognathic surgery for corrections of dentofacial deformities were used in the study. Dicom images were analyzed using the software Dolphin 3D 11.8. In the preoperative tomographies 4 thickness measurements were considered: A - 1.5 milimeter (mm) above the lingula. B - 1mm from the anterior border of the ramus (A and B points at the height of the medial osteotomy cut). C - 5mm distally to the second molar and 5mm from the upper border of the mandible (retromolar region) D - In the region between the mesial and distal roots of the first and second mandibular molars. In the postoperative tomographies the exams were analyzed and classified according to the fracture pattern described in the literature, where I (true Hunsuk), II (posterior cortical of the branch), III (through the mandibular canal) and IV (bad split). The data were analyzed by the Kruskal-Wallis test followed by the Dunn post-test. Results showed 35 type I fractures, 01 type II fracture, 19 type III fractures and 07 type IV fractures. Type I presented the highest thickness average values for the four considered measurements, whereas type IV presented the lowest values for all measurements... (Complete abstract click electronic access below) / Mestre

Orthognatic surgery deals with congenital and acquired dentoalveolar or skeletal deformities of the face. An unfavourable downward rotation of a mandible and posterior vertical maxillary excess cause an anterior open bite, which is characterized by excessive anterior facial height in the lower third, a gap between the incisors in maximal occlusion and a large mandibular angle. Osteotomy (mainly Le Fort I osteotomy or bilateral sagittal split osteotomy of the mandibular ramus - BSSO), ostectomy or distraction osteogenesis are performed to correct the orthognatic deformities. Osteosynthetic materials based on titanium or bioresorbable materials are used in the form of miniplates with monocortical screws, or bicortical screws are utilized to fix the bony fragments. Stability of the new jaws position is the main criterion for success. Relapse causes a loss of occlusion and consequently functional and aesthetic disorders. Relapse consists of skeletal and dental factors. Skeletal relapse is usually divided into early and long-term relapse. BSSO with counter-clockwise (CCW) rotation of the occlusal plane alone was traditionally considered to be the least stable treatment method. Some authors suggest the use of two miniplates on each side of the osteotomy, but we have not found scientific proof of the...

Orthognatic surgery deals with congenital and acquired dentoalveolar or skeletal deformities of the face. An unfavourable downward rotation of a mandible and posterior vertical maxillary excess cause an anterior open bite, which is characterized by excessive anterior facial height in the lower third, a gap between the incisors in maximal occlusion and a large mandibular angle. Osteotomy (mainly Le Fort I osteotomy or bilateral sagittal split osteotomy of the mandibular ramus - BSSO), ostectomy or distraction osteogenesis are performed to correct the orthognatic deformities. Osteosynthetic materials based on titanium or bioresorbable materials are used in the form of miniplates with monocortical screws, or bicortical screws are utilized to fix the bony fragments. Stability of the new jaws position is the main criterion for success. Relapse causes a loss of occlusion and consequently functional and aesthetic disorders. Relapse consists of skeletal and dental factors. Skeletal relapse is usually divided into early and long-term relapse. BSSO with counter-clockwise (CCW) rotation of the occlusal plane alone was traditionally considered to be the least stable treatment method. Some authors suggest the use of two miniplates on each side of the osteotomy, but we have not found scientific proof of the...