Pré-carga de parafuso com tratamento de superfície Diamond-like carbon: prevenção do desaperto / DLC screw preload. Loosening prevention

O desaperto do parafuso que une a prótese ao implante dentário é um dos motivos de falha da reabilitação protética ao longo do tempo. No entanto, o tratamento da superfície deste parafuso com Diamond-like carbon causa a redução do atrito e deslizamento entre os componentes, o que aumenta o benefício causado pela pré-carga aplicada no parafuso e diminui a probabilidade de ocorrer o desperto. Por meio desse relato de caso, procuramos ilustrar uma indicação clínica da associação entre a correta pré-carga aplicada e o parafuso com Diamond-like carbon, um protocolo otimizado para solucionar caso de recidiva de desaperto do parafuso em prótese unitária na região anterior de maxila.

The screw loosening is a reason to prosthetic rehabilitation failure. However, the DLC (Diamond-like carbon) screw treatment lead thefriction decrease and sliding between the components, which increases the screw preload benefit and decreases the chance of looseningoccurrence. This case shows a clinical indication of the association of the correct preload applied and the DLC screw, which can be consideredan optimized protocol to solve screw loosening recidivate of unitary prosthesis in anterior maxillary site.

In vitro integrity of implant external hexagon after application of surgical placement torque simulating implant locking

The aim of this study was to evaluate the integrity of the external hexagon of an implant system with internal and external hexagons but with prosthetic connection through the external hexagon (Internal Torque, IT) in comparison with that of an implant system with external hexagon with mount (External Hexagon, EH). A device was made to measure the rotational freedom angles between implant and abutment hexagons in 10 implants from each group after the application of surgical placement torques of 45, 60 and 80 Ncm simulating implant locking. The distances between the vertices of the external hexagon were also obtained. Rotational freedom data were subjected to ANOVA and Tukey's test (P < .05) showing no significant difference between the angles of the intact implants (EH - 3.31 ± 0.41° and IT - 3.30 ± 0.17°) and after application of a 45 Ncm torque (EH - 3.27 ± 0.38° and IT - 3.31 ± 0.22°). However, after application of a 60 Ncm torque there were significant differences (IT - 3.40 ± 0.20° and EH - 4.03 ± 0.54°). After application of a 80 Ncm torque, the IT implant presented values of 3.39 ± 0.21° whereas the EH did not support the torque, suffering deformation of its external hexagon. Within the limits of this study, it can be concluded that the IT implant system may be preferable in clinical situations where implant placement within a certain bone density could generate torques higher than 60 Ncm.