Fábio Ricardo Loureiro Sato

Comparative Biomechanical and Photoelastic Evaluation of Different Fixation Techniques of Sagittal Split Ramus Osteotomy in Mandibular Advancement

PURPOSE The aim of the present study was to comparatively evaluate the resistance and tension areas created after load incidence in different varieties of sagittal split ramus osteotomy fixation techniques. MATERIALS AND METHODS Fifty synthetic polyurethane hemimandible replicas were subjected to linear loading tests to evaluate 4 fixation techniques of the sagittal split ramus osteotomy using 2-mm system plates and screws. The hemimandibles were fixed with three 90 degrees linear screws, three 60 degrees linear screws, 3 screws in a reversed L arrangement, and one titanium miniplate. Each group was subjected to linear loading using an Instron 4411 servohydraulic mechanical testing unit. The load peak value and peak displacement were measured. Another 4 hemimandible replicas were made of photoelastic resin and subjected to photoelastic analysis after linear loading with a 3-mm displacement. RESULTS The results of the mechanical tests showed statistically significant differences between the fixation groups. The linear 90 degrees fixation and the reversed L arrangement presented with greater loading resistance, followed by the linear 60 degrees fixation and miniplates. In relation to the stress distribution in the photoelastic analysis, the fringes were concentrated near the osteotomy and to the lower part of the mandible in the linear 90 degrees -screw system and reversed L arrangement. In the case of the linear 60 degrees screws, most fringes were located around and between the screws. In the case of the miniplates, the fringes were concentrated around the screws near the osteotomy and more distally. CONCLUSION Under the conditions tested, the linear 90 degrees and reversed L arrangements provided the most favorable behavior.

Short-Term Outcome of Postoperative Patient Recovery Perception After Surgical Removal of Third Molars

PURPOSE The aim of this study was to depict surgical difficulties related to third molar removal with symptoms and signs presented by postoperative patients, identifying the most frequent occurrences and postoperative complications to prevent them or lessen their intensity. PATIENTS AND METHODS Data were acquired from questionnaires answered by patients and surgeons after surgery. A total of 128 patients participated in this study, answering questionnaires regarding postoperative signs/symptoms on a daily basis for a period of 7 days. Surgeons answered a questionnaire about the surgical procedure. RESULTS Main patient complaints were related to swelling and bad taste/breath, considering that the former was more intense during the first days after operation, and the latter lingered during the 7-day postoperative period of research. Pain was reportedly more intense during the first day after operation and presented continuous reduction throughout the recovery period. Mouth opening (trismus) and eating were the main activities affected by third molar extraction. A positive and significant relevance was only detected regarding surgical duration and difficulties encountered by the surgeon. There was no significant relation between the above-mentioned variables and average and peak pain during the postoperative period. CONCLUSION Results show that during the first postoperative week some patients nay experience quality reduction in their daily activities. Considering that objective (ie, surgery duration) and subjective (ie, difficulties during surgery) indicators were not related to postoperative pain, it was concluded that all patients are entitled to knowing that their lifestyles may be negatively affected by the after-effects, contributing to a better professional-patient relationship.

A comparative evaluation of the hybrid technique for fixation of the sagittal split ramus osteotomy in mandibular advancement by mechanical, photoelastic, and finite element analysis

OBJECTIVE This study evaluated the mechanical characteristics and stress distribution of the hybrid technique fixation of the sagittal split ramus osteotomy. STUDY DESIGN In the mechanical test, 10 polyurethane replicas of human hemimandibles of each group were submitted to linear loading test. For the photoelastic evaluation, 3 hemimandible replicas of photoelastic resin were subjected to photoelastic analysis. In the finite element analysis, 3 computer models simulated the displacement and the results of maximum principal stress were analyzed. RESULTS The results of this study demonstrated that the fixation technique with 3 bicortical screws presented better mechanical resistance and stress distribution pattern when compared with the hybrid technique that, on the other hand, presents better results in comparison with a miniplate and monocortical screws. CONCLUSIONS The results suggest that the hybrid technique increased the resistance and improved stress distribution of miniplate/monocortical screw fixation, maintaining most of the advantages of this technique.

Comparison of five different fixation techniques of sagittal split ramus osteotomy using three-dimensional finite elements analysis.

The aim of this study was to compare the mechanical stress over hemimandible substrate and hardware after sagittal split ramus osteotomy (SSRO) fixed with five different techniques using three-dimensional (3D) finite element analysis. A 3D finite element model of a hemimandible was created and a 5mm advancement SSRO was simulated on a computer model. The model was fixed with five different techniques: 3 linear 60° screw arrangement; 3 linear 90° screw arrangement; 3 inverted L screw arrangement; 1 conventional miniplate; and 1 locking miniplate with four monocortical screws. Load was applied until 3mm displacement was reached and the results were compared with previous mechanical and photoelastic tests, thus analysing the mechanical stresses developed in the proximity of miniplates and screws and within the fixation system itself. The maximum principal stress values demonstrate a lower mechanical stress rate in bone and in the fixation system with the inverted L arrangement, followed by the linear 90° and linear 60° arrangements. The locking miniplate/screw system presented lower maximum principal stress and better stress distribution compared with the conventional system. Under the conditions tested, the reversed L arrangement provided the most favourable stress dissipation behaviour.

Distraction osteogenesis of iliac bone graft as a reconstruction after central giant cell granuloma curettage.

This case report describes a successful aesthetic and functional reconstruction of a patient who had severe maxilla bony deficiency as a result of excision of central giant cell granuloma. Initially, the lesion was curetted plus peripheral ostectomy. The defect was reconstructed with iliac bone graft in a second step, with both surgeries performed under general anesthesia. Six months after second step, later vertical distraction osteogenesis was performed on the grafted maxilla to obtain a satisfactory bony height. Distraction osteogenesis can be a good alternative for the reconstruction of bone deficiencies associated to bone graft; however, it should be not done as first treatment in the severe pathologic jaw defects.

Estudio Radiográfico Prospectivo de la Reparación Ósea en Sínfisis Mandibular Posterior a la Remoción Ósea de Mentón

El retiro de hueso de sinfisis mandibular ha sido utilizado ampliamente para diferentes procedimientos reconstructivos maxilofaciales. El objetivo de esta investigacion fue establecer la existencia de la reparacion osea en el defecto creado en sinfisis debido al retiro de hueso. Treinta pacientes (22 mujeres, 8 hombres) de entre 21 y 65 anos fueron operados para retirar hueso de menton que fue posteriormente aplicado en reconstruccion osea alveolar; las cirugias fueron realizadas por dos cirujanos maxilofaciales y los pacientes fueron evaluados con telerradiografias en la etapa preoperatoria, postoperatoria inmediata (PIn) y postoperatoria tardia (PTar), donde se realizaron medidas horizontales y verticales del defecto oseo; los valores fueron estudiados con la prueba t de Student con valor de p<0,05. Luego del retiro oseo se observo un defecto vertical promedio de 12,80±1,99 y horizontal de 8,33±1,77; luego de un ano, se obtuvo una disminucion de 32,8% en el sentido vertical y 50,3% horizontal, presentando significancia estadistica en relacion al PIn. Se concluye que existe reparacion osea del defecto originado en sinfisis siendo proximo al 30%-50% en la evaluacion de un ano posterior a la cirugia.

Sequência de Pierre Robin – Etiopatogenia, Características Clínicas e Formas de Tratamento☆

Resumo Recem-nascidos com Sequencia de Robin frequentemente apresentam serias obstrucoes respiratorias que podem representar riscos a vida resultante de malformacoes anatomicas (micrognatia, glossoptose e potenciais fendas palatinas). Esses pacientes precisam de medidas terapeuticas imediatas e efectivas. Dessa forma, o objectivo desse trabalho foi fazer uma revisao de literatura sobre a etiopatogenia, principais caracteristicas e as actuais formas de tratamento empregadas para os portadores dessas alteracoes estruturais.

Biomechanical analysis on different fixation techniques for treatment of mandibular body fractures

Aim: To biomechanically analyze two fixation techniques in polyurethane hemi-mandibular bodyfractures, using a universal testing machine. Methods: The study employed 10 polyurethanehemi-mandible replicas, which simulated simple fractures of the mandibular body, divided into twogroups: one group comprised 5 hemi-mandibles with two 2.0 mm system plates in the tension andcompression zones, while the other group contained 5 hemi-mandibles with an Erich bar and a2.0 mm system plate in the tension and neutral zones, respectively. Data were analyzed statisticallyby the Student’s t-test (α=0.05) Results: The test results indicated that the fixation using 2.0 mmsystem plates offered significantly more resistance to the loads and presented significantly largerdisplacement compared to the fixation using just one 2.0 mm system plate and the Erich bar.Conclusions: It may be concluded that the use of two plates in the 2.0 mm system had greatermechanical strength than a single 2.0 mm plate combined with an Erich bar. Clinically, it is knownthat both techniques can provide good results, but patients receiving the combination of Erich barand one plate are required to be more cooperative during the postoperative period, especiallywith respect to the prescribed diet in order to avoid failures in this system. (AU)

TMJ Total Joint Prosthesis for Condylar Fracture Malunion

In the international literatura exist some information related to temporomandibular joint (TMJ) involvement in condylar fracture malunion; the treatment is variated being executed with a bone reconstruction, ramus vertical osteotomy or condilar plate. This case demonstrates that TMJ replacement with prosthetic joint is technically possible and appropriate in the case of malunion of condylar fracture.

Evaluation of two palatoplasty techniques in patients with cleft palate

Introduction: The aim of this study was to make a comparative evaluation between two palatoplasty techniques Von Langenbeck and Veau-Wardill-Kilner by evaluating if such techniques succeed in closing the palatine fissure and correcting hypernasality. Methods: Patients undergoing palatoplasty surgery in the period from 2011 to 2014 by means of the Oral and Maxillofacial Surgery Department of the Hospital of Face Defects were selected and requested to undergo a new evaluation. The medical records of patients who attended the new evaluation were assessed as to the number of surgeries performed and patients undergoing physical examination to check for the presence of fistulas, and they were asked about the improvement in hypernasality. Results: 10 out of the total number of operated patients attended for evaluation, and none of them had an oronasal fistula. The Von Langenbeck technique proved to be effective in 67% of the cases in closing the gap in the first surgery, whereas the Veau-Wardill-Kilner technique was effective in 50% of the cases. Concerning the correction of hypernasality, Von Langenbeck was effective in 67% of the case, and Veau-Wardill-Kilner, in 75%. Conclusion: The Von Langenbeck technique was more effective in closing the Cleft Palate and Cleft Lip, while Veau-Wardill-Kilner technique was effective in correcting hypernasality. Correspondence to: Dr. Fábio Ricardo Loureiro Sato, Oral and Maxillofacial Surgery Area, State University of São Paulo – UNESP, College of Dentistry – São José dos Campos, Av. Eng. Francisco José Longo, 777 – 12245-000 São José dos Campos – SP – Brazil; Phone/Fax: +55 12 3947-9000; E-mail: fabio.sato@ict.unesp.br