Tightening techniques for the retaining screws of universal abutment / Técnicas de aperto para parafusos de retenção do pilar universal

Purpose: This study evaluated the torque maintenance of universal abutment retaining screws using different tightening techniques, and coated or uncoated screws. Material and method: The screws were tightened to implants as following: Control - 32 Ncm torque; H20 - holding 32 Ncm torque for 20 s; R - 32 Ncm torque, repeated after 10 min (retorque); and H20+R - combining the two tightening techniques. Titanium and coated screws were also evaluated. Result: Statistical analysis showed higher maintained torque for titanium screws (p< 0.001). The H20+R technique showed the highest maintained torque (p=0.003), but the H20 technique's maintained torque was similar. Conclusion Titanium screws associating the two tightening techniques can improve maintained torque.

Objetivo: Este estudo avaliou a manutenção do torque de parafusos de retenção do pilar universal utilizando diferentes técnicas de aperto e parafusos com ou sem revestimento. Material e método: Os parafusos foram apertados nos implantes da seguinte forma: Controle - 32 Ncm de torque; H20 - segurando os 32 Ncm de torque por 20 s; R - 32 Ncm de torque, repetido após 10 min (retorque); e H20+R - combinando as duas técnicas de aperto. Foram também avaliados parafusos de titânio com e sem revestimento da rosca. Resultado: A análise estatística mostrou maior manutenção do torque de parafusos de titânio (p< 0,001). A técnica H20+R apresentou a maior manutenção do torque (p=0,003), semelhante a manutenção do torque da técnica H20. Conclusão: Parafusos de titânio combinando as duas técnicas de aperto pode melhorar a manutenção do torque.

Loosening torque of Universal Abutment screws after cyclic loading: influence of tightening technique and screw coating.

PURPOSE: The purpose of this study was to evaluate the influence of tightening technique and the screw coating on the loosening torque of screws used for Universal Abutment fixation after cyclic loading. MATERIALS AND METHODS: Forty implants (Titamax Ti Cortical, HE, Neodent) (n=10) were submerged in acrylic resin and four tightening techniques for Universal Abutment fixation were evaluated: A - torque with 32 Ncm (control); B - torque with 32 Ncm holding the torque meter for 20 seconds; C - torque with 32 Ncm and retorque after 10 minutes; D - torque (32 Ncm) holding the torque meter for 20 seconds and retorque after 10 minutes as initially. Samples were divided into subgroups according to the screw used: conventional titanium screw or diamond like carbon-coated (DLC) screw. Metallic crowns were fabricated for each abutment. Samples were submitted to cyclic loading at 10(6) cycles and 130 N of force. Data were analyzed by two-way ANOVA and Tukey's test (5%). RESULTS: The tightening technique did not show significant influence on the loosening torque of screws (P=.509). Conventional titanium screws showed significant higher loosening torque values than DLC (P=.000). CONCLUSION: The use of conventional titanium screw is more important than the tightening techniques employed in this study to provide long-term stability to Universal Abutment screws.