Volumetric study of sphenoid sinuses: anatomical analysis in helical computed tomography.

PURPOSE: The sphenoid sinus is the most inaccessible part of the face, being inside the sphenoid bone and closely related to numerous vital neural and vascular structures. The objective of this study was to analyze and evaluate the variation of anatomy and the volume of the sphenoid sinus using helical computed tomography and medical imaging software. MATERIALS AND METHODS: A total of 47 helical CT scans of sinuses of male and female individuals aged 18-86 years were selected. The images were formatted using ITK-SNAP software, consisting of three steps: (1) segmentation; (2) volumetric analysis and (3) 3D reconstruction. The sphenoid sinuses were also classified according to Hammer, i.e., in conchal, pre-sellar, sellar and post-sellar types. A single investigator, who is specialist in dental radiology and was trained and calibrated, performed the volume and image analysis. After 15 days, the segmentations were repeated. RESULTS: The Dunn's multiple comparison test revealed significant differences in the volume rankings between the right and left sides (P = 0.0002), with the post-sellar type presenting the greatest volume on the right side compared to pre-sellar and sellar types. In the left sphenoid sinuses, the post-sellar type showed the greatest volume. The Lin's correlation coefficient showed excellent reproducibility values. CONCLUSIONS: According to the applied methodology, it was found that the volume of the sphenoid sinus was influenced by neither age nor gender (P > 0.005). There was difference in the volumes of sphenoid sinus on the right and left sides and in the anatomical classification.

Avaliação da resistência ao cisalhamento de braquetes da técnica lingual colados sobre superfície cerâmica / Evaluation of shear strength of lingual brackets bonded to ceramic surfaces

OBJETIVO: avaliar a resistência ao cisalhamento de braquetes metálicos (American Orthodontics) utilizados na técnica lingual, colados em facetas de cerâmica. MÉTODOS: foram utilizados 40 corpos de prova divididos em quatro grupos de 10, de acordo com o material de colagem e do preparo da porcelana: Grupo I -resina Sondhi Rapid-Set e ácido fluorídrico; Grupo II -resina Sondhi Rapid-Set e óxido de alumínio; Grupo III -resina Transbond XT e ácido fluorídrico; e Grupo IV -resina Transbond XT e óxido de alumínio. Previamente à colagem, os braquetes foram preparados com base de resina de carga pesada (Z-250) e as facetas de cerâmica receberam aplicação de silano. O teste de cisalhamento foi realizado por uma máquina de ensaios Kratos à uma velocidade de 0,5mm/min. RESULTADOS: os resultados obtidos foram analisados estatisticamente através do teste de Tukey (p<0,05) e demonstraram diferença significativa entre os grupos I (2,77MPa) e IV (6,00MPa), e entre os grupos III (3,33MPa) e IV. CONCLUSÕES: concluiu-se que a colagem de braquetes da técnica lingual em superfície de cerâmica foi mais resistente ao cisalhamento com o uso de óxido de alumínio associado às duas resinas utilizadas neste estudo, porém a resina Transbond XT apresentou maior resistência que a Sondhi Rapid-Set.

OBJECTIVE: The aim of this study was to evaluate the shear strength of lingual metal brackets (American Orthodontics) bonded to ceramic veneers. METHODS: A total of 40 specimens were divided into four groups of 10, according to bonding material and ceramics preparation: Group I -Sondhi Rapid-Set resin and Hydrofluoric acid, Group II -Sondhi Rapid-Set resin and aluminum oxide, Group III -Transbond XT resin and Hydrofluoric acid, and Group IV -Transbond XT resin and aluminum oxide. Prior to bonding, the brackets were prepared with heavy-duty resin base (Z-250) and the ceramic veneers were treated with silane. The shear test was conducted with a Kratos testing machine at a speed of 0.5 mm/min. RESULTS: The results were statistically analyzed by the Tukey test (p<0.05) and showed a statistically significant difference between groups I (2.77 MPa) and IV (6.00 MPa), and between groups III (3.33 MPa) and IV. CONCLUSION: In conclusion, the bonding of lingual brackets to ceramic surfaces exhibited greater shear strength when aluminum oxide was used in association with the two resins utilized in this study, although Transbond XT showed greater shear strength than Sondhi Rapid-Set.