Effect of Thermomechanical Fatigue on Shear Strength between a Conventional and an Experimental Polymer for Prosthetic Application

The incorporation of antimicrobial agents may influence the mechanical properties of acrylic resins. Thus, the use of these agents only in regions of dental prostheses subject to greater contamination may be an alternative. This study evaluates the effect of thermomechanical fatigue on the bond strength between a conventional and an experimental acrylic resin incorporated with nanostructured silver vanadate decorated with silver nanoparticles (AgVO 3 ). 60 specimens (O13mm x 23mm height) in self-curing resin were obtained and divided into groups according to the experimental resin incorporated with AgVO 3 (O4mm x 6mm height): G1–Conventional x Conventional , G2–Conventional x 2.5% of AgVO 3 , G3–Conventional x 5% of AgVO 3. Ten samples of each group were subjected to bond strength analysis after manufacture, and 10 were previously submitted to 1.200.000 cycles with 98N load and 2Hz/second frequency and alternating baths of 5 oC, 37oC and 55 oC. The fracture area was analyzed.  The data were submitted to analysis of variance of two-factors with Bonferroni adjustment for  post hoc  comparisons (α=0.05) was used. The fatigue did not affect the bond strength (p=0.416), however, there was influence of the AgVO 3 concentration on the bond strength between the resins (p=0.013). Mixed failures with adhesive predominance were observed in samples without AgVO 3 and cohesive failures in samples with the nanomaterial. The use of AgVO 3 can improve or maintain the bond strength between resins with no thermomechanical fatigue influence. Keywords: Acrylic Resins. Products with Antimicrobial Action. Nanotechnology. Thermomechanical fatigue Resumo A incorporacao de agentes antimicrobianos pode influenciar nas propriedades mecânicas de resinas acrilicas. Desta forma, o uso destes agentes apenas em regioes das proteses dentarias sujeitas a maior contaminacao pode ser uma alternativa. Este estudo avalia o efeito da fadiga termomecânica na resistencia de uniao entre uma resina acrilica convencional e uma experimental incorporada com vanadato de prata nanoestruturado decorado com nanoparticulas de prata (AgVO 3 ). Foram obtidos 60 especimes (O13mm x 23mm de altura) em resina autopolimerizavel, divididos em grupos de acordo com a resina experimental incorporada com AgVO 3 (O4mm x 6mm de altura): G1-Convencional x Convencional, G2-Convencional x 2,5% de AgVO 3 , G3 -Convencional x 5% de AgVO 3 . Dez amostras de cada grupo foram submetidas a analise de resistencia a uniao apos a confeccao e 10 foram submetidas previamente a 1.200.000 ciclos com carga de 98 N e frequencia de 2Hz/segundo e banhos alternados de 5 oC, 37 oC e 55 oC. A area de fratura foi analisada. Os dados foram submetidos a analise de variância de dois fatores com ajuste de Bonferroni para comparacoes pos hoc (α = 0,05). A fadiga nao afetou a forca de uniao (p=0,416), no entanto, houve influencia da concentracao de AgVO 3 na resistencia de uniao entre as resinas (p=0,013). Falhas mistas com predominância adesiva foram observadas nas amostras sem AgVO 3 e falhas coesivas nas amostras contendo o nanomaterial. O uso de AgVO 3 pode melhorar ou manter a resistencia da uniao entre as resinas sem influencia da fadiga termomecânica. Palavras-chave: Resinas Acrilicas. Produtos com Acao Antimicrobiana. Nanotecnologia.