Torque loss under mechanical cycling of long-span zirconia and titanium-cemented and screw-retained implant-supported CAD/CAM frameworks

Autor(es)

Gomes, Erica Alves ^[1] ; Tiossi, Rodrigo ^[1] ; Lapria Faria, Adriana Claudia ^[1] ; Rodrigues, Renata C. S. ^[1] ; Ribeiro, Ricardo Faria ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Dent Sch Ribeirao Preto, Dept Dent Mat & Prosthodont, BR-14049 Ribeirao Preto - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Clinical Oral Implants Research; v. 25, n. 12, p. 1395-1402, DEC 2014.
• Citações Web of Science: 3

Resumo

Objectives: This study evaluated the screw joint stability after cyclic loading of implant-supported titanium and zirconia CAD/CAM frameworks for fixed dental prostheses (FDPs) with different retention methods. Material and methods: Twenty four one-piece frameworks supported by six threaded implants placed in the maxilla were fabricated using a CAD/ CAM technique (NeoShape). Dry-pressed porcelain crowns were luted to the frameworks to standardize the specimens. The specimens were then divided into four groups (n = 6) according to framework material (titanium or zirconia) and retention method for the prosthesis (cement-or screw-retained): G1, Ti-cemented; G2, Ti-screw-retained; G3, Zr-cemented; and G4, Zr-screw-retained. A digital torque ratchet was used to assess the initial preload removal torque. Torque was then reapplied and the specimens were submitted to a 200 N cyclic load, at a frequency of 2 Hz, underwater in controlled temperature of 37 degrees, and for 1 x 10(6) cycles. An opposing lower dental arch was fabricated using bis-acrylic resin to simulate occlusal contacts in centric. After cyclic loading, postload removal torque was measured. Preload and postload torque loss was expressed as a percentage of the initial load. Data were submitted to a linear mixed-effects model for statistical significance (alpha = 0.05) to evaluate the effect of cyclic loading in the screw torque loss used with frameworks of different materials and retention methods. Results: Significant screw torque loss (%) was found for the tested groups (before/after cyclic loading, respectively): G1 (39.77/61.83), G2 (37.57/50.96), G3 (34.87/54.10), and G4 (47.56/73.50) (P < 0.05). Conclusions: The screw removal torque was significantly reduced for all groups in this study after cyclic loading the specimens. Screw-retained zirconia specimens presented the highest torque loss before and after the cyclic loadings compared with the other specimens that were tested. (AU)

• Processo FAPESP: 10/02218-5 - Influência da ciclagem mecânica no desrosqueamento do parafuso de retenção em próteses parciais fixas cimentadas e parafusadas confeccionadas pelo sistema CAD/CAM titânio e zircônia. Análise in vitro e análise não-linear pelo MEF-3D
• Beneficiário: Ricardo Faria Ribeiro
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 10/00124-3 - Influência da ciclagem mecânica no desrosqueamento do parafuso de retenção em próteses parciais fixas cimentadas e parafusadas confeccionadas pelo sistema CAD/CAM titânio e zircônia. Análise in vitro e análise não-linear pelo MEF-3D.
• Beneficiário: Erica Alves Gomes
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado