Parafusos em UCLA's

   Como sempre gosto de frisar, trabalhamos com evidências. Na última edição do International Jornal of Oral Implantology, autores brasileiros publicaram um artigo utilizando diversos tipos de UCLA's e parafusos, buscando avaliar qual melhor opção para evitar o afrouxamento dos parafusos sobre este tipo de conexão. Todos os grupos testados afrouxaram os parafusos e nenhum teve diferenças estatisticamente significantes. Isso quer dizer que o uso de UCLA para reabilitações em HE tem um risco previsto de afrouxamento do parafuso, portanto devendo ser verificado a cada manutenção. Se afrouxa, obviamente que a margem de contato entre UCLA e implante sofre movimentação, podendo causar irritação marginal também.
   Com Cone Morse ou Morse Taper isso não ocorre.
   Para sua atualização:

Preload Evaluation of Different Screws in External Hexagon Joint

Assunção, Wirley Gonçalves DDS, MSc, PhD; Delben, Juliana Aparecida DDS, MSc; Tabata, Lucas Fernando DDS, MSc, PhD; Barão, Valentim Adelino Ricardo DDS, MSc, PhD; Gomes, Érica Alves DDS, MSc, PhD; Garcia, Idelmo Rangel Jr. DDS, MSc, PhD

Abstract

Purpose: This study compared the maintenance of tightening torque in different retention screw types of implant-supported crowns.

Materials and Methods: Twelve metallic crowns in UCLA abutments cast with cobalt-chromium alloy were attached to external hexagon osseointegrated implants with different retention screws: group A: titanium alloy retention screw; group B: gold alloy retention screw with gold coating; group C: titanium alloy retention screw with diamond-like carbon film coating; and group D: titanium alloy retention screw with aluminum titanium nitride coating. Three detorque measurements were obtained after torque insertion in each replica. Data were evaluated by analysis of variance (ANOVA), Tukey's test (P < 0.05), and t test (P < 0.05).

Results: Detorque value reduced in all groups (P < 0.05). Group A retained the highest percentage of torque in comparison with the other groups (P < 0.05). Groups B and D retained the lowest percentage of torque without statistically significant difference between them (P > 0.05).

Conclusions: All screw types exhibited reduction in the detorque value. The titanium screw maintained the highest percentage of torque whereas the gold-coated screw and the titanium screw with aluminum titanium nitride coating retained the lowest percentage.