Objetivo: Avaliar sistemas de retenção a grampo em próteses obturadoras cirúrgicas em diferentes ressecções maxilares. Método: Diferentes modelos maxilares, confeccionados em resina acrílica ativada quimicamente (RAAQ), receberam próteses obturadoras cirúrgicas, sendo a amostra constituída pelos grupos: Grupo 1 -grampo circunferencial (grampo C) no 1º e no 2º molares superiores do lado oposto à ressecção e arco labial de Hawley (G1a -Classe II de Aramany, G1b -Classe II de Aramany sem canino superior e G1c -Classe I de Aramany); Grupo 2 -grampo C no 1º e no 2º pré-molar e no 1º e 2º molar (G2 -Classe I de Aramany). A ciclagem mecânica ocorreu com intervalos de 0, 28, 120, e 360 ciclos de inserção e remoção, considerando-se quatro remoções diárias por um período de três meses; testes de resistência à tração foram realizados no início e após cada intervalo da ciclagem mecânica. Resultados: Todos os grupos apresentaram diminuição da retenção ao longo da ciclagem. O grupo G2 se manteve superior em todos os momentos avaliados, seguido em ordem decrescente pelos grupos G1a, G1b e G1c. A redução da retenção nos grupos 1a, 1b e 1c não foi estatisticamente significante até o ciclo 120. O grupo G2 apresentou redução significante da retenção no ciclo 28, não significante no ciclo 120, mas significante no ciclo 360. Conclusão: A substituição do arco de Hawley por grampos circunferencias nos pré-molares proporciona maior retenção. A retenção proporcionada pelo sistema com arco labial de Hawley é dependente da amplitude da perda, onde quanto maior a perda menor a retenção; a expressiva perda de retenção após o período de 1 mês sugere a necessidade de ativação periódica dos sistemas de retenção.Neoplasias bucais; Prótese maxilofacial; Resistência à tração.Objective: To evaluate clasp retention systems in surgical obturator prostheses after different maxillary resections. Method: Different chemically activated acrylic resin maxillary models received surgical obturator prostheses, in a sample constituted by the following groups: Group 1 -circumferential clasp (C clasp) in the first and second maxillary molars contralateral to the resection and Hawley labial bow (G1a -Aramany Class II, G1b -Aramany Class II without maxillary canine and G1c -Aramany Class I); Group 2 -C clasp in the first and second premolar and in the first and second molar (G2 -Aramany Class I). Mechanical cycling was performed at intervals of 0, 28, 120 and 360 insertion/removal cycles, considering four daily removals during a 3-month period. Tensile strength tests were performed in the beginning and at each interval of the mechanical cycling. Results: All groups presented a decrease of retention along the cycling period. The group G2 was superior to the others at all evaluated moments, followed by the groups G1a, G1b and G1c in a decreasing order. The decrease of the retention in the groups G1a, G1b and G1c was not statistically significant up to cycle 120. Group G2 presented a significant reduction of retention at cycle 28, non-significant at cycle 120 and si...

The CAD/CAM technology available in the biomedical area gave rise to the development of this study in order to evaluate the dimensional stability of orbital prosthesis. Face computerized tomography of 15 adults, men and women older than 25 years of age not bearing congenital or acquired craniofacial defect, were processed in CAD (computer-aided design) software to produce 30 reverse tridimensional models of the orbital region. These models were then processed in the CAM system (computer-aided manufacturing), by means of laser selective sintering, to generate surface prototypes of the orbital region. Two facial impressions of each subject provided 15 pairs of cast models and orbital defects were performed either in the right or left side of each stone model. The surface prototypes were adapted in the casts and then flasked to be processed in silicone. The demarcation of anthropometric landmarks within the prosthesis and in the face midline defined 31 linear measurements, used to evaluate the dimensional stability of the orbital prostheses and its location in the face. In conclusion, the comparative analyses of the measurements, observed in the prostheses and in the opposite sides that originated the surface prototypes, showed that silicone orbital prostheses presented similar vertical, transversal and oblique dimensions, as well as similar depth. There is no transverse or oblique displacement of the prostheses. Combined measurements in the prostheses' side are not stable regarding the opposite side. The dimensional stability of orbital prostheses suggests that the CAD/CAM system evaluated herein may be used with clinical purposes.

Aim: To evaluate the dimensional stability of a new facial molding technique using thermoplastic custom molding tray. Methods: The designs established demarcation of facial anthropometrics landmarks, making linear measurements with a digital caliper. Facial molding was carried out using thermoplastic custom trays, constructing a facial plaster cast with the anthropometric landmarks already transferred by measuring the linear dimensions on the plaster cast and statistical analysis. Results: All linear measurements in the palpebral and labial regions presented statistically significant distortions. Only one of the linear measurements from the orbital region did not demonstrate any significant distortion. The nasal region presented the least amount of distortion. Conclusions: Although statistically significant, distortions were due to the method of breathing and were considered to be clinically irrelevant. The reduction in the working time, the comfort provided to the patient and the dimensional accuracy of the plaster cast obtained by the facial molding technique using custom perforated molding tray suggest that this technique should be employed for making facial prostheses.