RESUMO
The influence of angled abutments on stress of peri-implant bone is a controversial issue. It is widely accepted that the use of angled abutments will increase adverse stress distributions on implants and surrounding bones. However, comparisons of clinical success rates of implants restored with angled and straight abutments indicate no significant differences. This review summarized the clinical application and biomechanical research associated with angled abutments. The use of angled abutments did not detrimentally affect the retention of dental implants, and tt was possible that the magnitude of stress within peri-implant bone increased or decreased under different conditions. Therefore, further researches should be conducted to confirm that favorable peri-implant stress levels may be induced if suitable angulation of abutments is selected.
RESUMO
Purpose: This study evaluated pre-tightening maintenance in abutment and prosthetic screwsof external and internal hexagon implant with straight and angled abutments. Methods: Four groups of implants and abutments were assessed combining internal andexternal hexagon and straight and angled abutments, which were retained by titanium screws tightened to 20 N.cm. Crowns were retained with gold screws tightened at 10 N.cm. A verticalline was ascribed across the implant-abutment-crown interface to verify horizontal displacement by a light microscope. The fatigue tests were performed in a servo-hydraulic machine, which delivered forces between 100 and 120 N for 250,000 cycles. The screw was removed, and the detorque value was recorded. Data were analyzed with 2-way ANOVA and Tukey's test. Results: No horizontal displacement was observed on the interface of implant-abutment or abutment and crown. It was found significant difference for prosthetic screw between implant connection types, but without interaction with abutment. However, for abutment screw, there was a difference between implant connection types and abutment with interaction between implant and abutments. The straight abutment showed significant better performance than the 17º angled abutment. Conclusion: The connection implant types or abutment affected pre-tightening maintenance. Internal and external hexed connections were effective to avoid horizontal displacement of crowns.
Objetivo: Este estudo avaliou a manutenção do pré-aparafusamento em pilar e parafuso protético de implantes com hexágono interno e externo, com pilares retos e angulados. Metodologia: Quatro grupos de implantes e pilares foram avaliados, combinando-se ohexágono interno ou externo e o pilar reto ou angulado, os quais foram retidos por parafusos de titânio aparafusados 20 N.cm. As coroas fora retidas com parafusos de ouro aparafusadosa 10 N.cm. Uma linha vertical foi delineada sobre a interface implante-pilar-coroa para verificar o deslocamento vertical com uso de microscópio ótico. Os testes de fadiga foram realizados em uma máquina servo-hidráulica, que promoveu forças entre 100 e 120 N por 250.000 ciclos. O parafuso foi removido e o valor de detorque for registrado. Os dadosforam analisados por ANOVA de dois fatores e teste de Tukey. Resultados: Nenhum deslocamento horizontal foi observado na interface implante-pilar oupilar-coroa. Observou-se uma diferença significativa para o parafuso protético entre os tipos de conexão do implante, mas sem interação com o pilar. Porém, para o parafuso do pilar houve diferença entre tipos de conexão e pilar, com interação entre pilar e implante. O pilar reto mostrou melhor performance que o pilar angulado a 17°. Conclusão: Os tipos de conexão do implante ou pilar afetaram a manutenção do pré aparafusamento. As conexões de hexágono interno e externo foram efetivas para evitar o deslocamento horizontal das coroas.