Adesão química entre cimento resinoso e cerâmicas: efeito no comportamento mecânico e na resistência de união

Abstract

Extensive loss of dental tissue due to advanced caries or trauma can be treated with indirect restorations using prosthetic elements. Ceramic restorations are widely used in modern dentistry due to their aesthetic and mechanical properties. To achieve both mechanical and chemical adhesion, hydrofluoric acid combined with silane is used on glass-ceramics, while, in addition to sandblasting with aluminum oxide, 10-methacryloyloxydecyl dihydrogen phosphate (MDP) has been employed to promote adhesion of zirconia-based polycrystalline ceramics. Considering the main technical failures of these restorations, they can occur due to mechanical factors related to the ceramic material or due to loss of adhesion. To explore the mechanical and adhesive effects of adhesive cementation, this thesis is divided into three studies. The first was a systematic review and meta-analysis comparing the mechanical performance of ceramic restorations with and without chemical adhesion between cement and ceramic. It was observed that chemical adhesion promotes mechanical reinforcement of glass and alumina-based ceramics; however, this effect was not observed in zirconia-based ceramics. The second study was an in vitro work aimed at exploring the fatigue mechanical behavior of simplified anatomy lithium disilicate crowns in the face of simulated progressive loss of chemical adhesion between ceramic and cement. It was observed that chemical adhesion between ceramic and cement is essential for better fatigue mechanical behavior. Additionally, the mechanical performance of the crowns significantly decreases when the occlusal portion of the crown lacks chemical adhesion. There is also an increase in stress concentration in the crown and cement layer with the progressive loss of chemical adhesion on the crown walls. The third study was an in vitro work aimed at investigating whether MDP-containing luting components at different stages of the adhesive process and the combination of MDP-containing materials could produce a favorable additive effect on microshear bond strength and fatigue behavior in simplified zirconia restorations stabilized by 4 mol% yttria (4YSZ) bonded to epoxy resin. It was found that luting systems with MDP-containing primers or adhesives associated with non-MDP resin cements demonstrated greater long-term bond strength for 4YSZ. Despite this, all luting systems exhibited similar fatigue behavior for 4YSZ bonded to epoxy resin. This thesis observed that chemical adhesion is essential to ensure the mechanical success of glass-ceramicbased restorations, whereas zirconia-based ceramics do not benefit from this. For 4YSZ, adhesive cementation using an MDP-containing primer or adhesive associated with non-MDP resin cements provides excellent bond strength results.