Effect of unilateral misfit on preload of retention screws of implant-supported prostheses submitted to mechanical cycling

Autor(es)

Assuncao, Wirley Goncalves ^[1] ; Ricardo Barao, Valentim Adelino ^[1] ; Delben, Juliana Aparecida ^[1] ; Gomes, Erica Alves ^[1] ; Garcia, Jr., Idelmo Rangel ^[2]

Afiliação do(s) autor(es)

^[1] Univ Estadual Paulista UNESP, Aracatuba Dent Sch, Dept Dent Mat & Prosthodont, Jose Bonifacio 1193, BR-16015050 Sao Paulo - Brazil

^[2] Univ Estadual Paulista UNESP, Aracatuba Dent Sch, Dept Surg & Integrated Clin, Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF PROSTHODONTIC RESEARCH; v. 55, n. 1, p. 12-18, JAN 2011.
• Citações Web of Science: 18

Resumo

Purpose: The aim of this study was to evaluate the effect of different levels of unilateral angular misfit on preload maintenance of retention screws of single implant-supported prostheses submitted to mechanical cycling. Materials and methods: Premachined UCLA abutments were cast with cobalt-chromium alloy to obtain 48 crowns divided into four groups (n = 12). The crowns presented no misfit in Group A (control group) and unilateral misfits of 50 mu m, 100 mu m and 200 mu m in the groups B, C and D, respectively. The crowns were attached to external hexagon implants with a titanium retention screw with torque of 30 N/cm. Oblique loading of 130 N at 2 Hz was applied on each replica, totalizing 5 x 10(4) and 1 x 10(6) cycles. Detorque values were measured initially and after each cycling period. Data were evaluated by analysis of variance and Tukey's HSD test (p < 0.05). Results: All groups presented reduced initial detorque values (p < 0.05) in comparison to the insertion torque (30 +/- 0.5 N/cm) and Group A (25.18 N/cm) exhibited the lowest reduction. After mechanical cycling, all groups presented detorque values from 19.5 N/cm to 22.38 N/cm and the mechanical cycling did not statistically influence the detorque values regardless the misfit level of the replicas. Conclusion: The unilateral misfit influenced the preload maintenance only before mechanical cycling. The mechanical cycling did not influence the torque reduction. (C) 2010 Japan Prosthodontic Society. Published by Elsevier Ireland. All rights reserved. (AU)

• Processo FAPESP: 05/56804-4 - Efeito da ciclagem mecanica no sistema coroa-implante-parafuso de retencao de protese sobre implante sem adaptacao passiva.
• Beneficiário: Wirley Goncalves Assuncao
• Modalidade de apoio: Auxílio à Pesquisa - Regular