Engineering Interfacial Integrity with Hydrolytic-Resistant, Self-Reinforcing Dentin Adhesive.

The leading cause of composite restoration failure is secondary caries, and although caries is a multifactorial problem, weak, damage-prone adhesives play a pivotal role in the high susceptibility of composite restorations to secondary caries. Our group has developed synthetic resins that capitalize on free-radical polymerization and sol-gel reactions to provide dental adhesives with enhanced properties. The resins contain γ-methacryloxypropyltrimethoxysilane (MPS) as the Si-based compound. This study investigated the properties of methacrylate-based resins containing methacryloxymethyltrimethoxysilane (MMeS) as a short-chain alternative. The degree of conversion (DC), polymerization kinetics, water sorption, mechanical properties, and leachates of MMeS- and MPS-resins with 55 and 30 wt% BisGMA-crosslinker were determined. The formulations were used as model adhesives, and the adhesive/dentin (a/d) interfaces were analyzed using chemometrics-assisted micro-Raman spectroscopy. The properties of the 55 wt% formulations were comparable. In the 30 wt% BisGMA formulations, the MMeS-resin exhibited faster polymerization, lower DC, reduced leachates, and increased storage and loss moduli, glass transition (Tg), crosslink density, and heterogeneity. The spectroscopic results indicated a comparable spatial distribution of resin, mineralized, and demineralized dentin across the a/d interfaces. The hydrolytically stable experimental short-chain-silane-monomer dental adhesive provides enhanced mechanical properties through autonomous strengthening and offers a promising strategy for the development of restorative dental materials with extended service life.

Durable bonds at the adhesive/dentin interface: an impossible mission or simply a moving target? / Durabilidade da adesão na interface adesivo/dentina: uma missão impossível ou simplesmente um alvo em movimento?

Composite restorations have higher failure rates, more recurrent caries and increased frequency of replacement as compared to dental amalgam. Penetration of bacterial enzymes, oral fluids, and bacteria into the crevices between the tooth and composite undermines the restoration and leads to recurrent decay and failure. The gingival margin of composite restora tions is particularly vulnerable to decay and at this margin, the adhesive and its seal to dentin provides the primary barrier between the prepared tooth and the environment. The intent of this article is to examine physico-chemical factors that affect the integrity and durability of the adhesive/dentin interfacial bond; and to explore how these factors act synergistically with mechanical forces to undermine the composite restoration. The article will examine the various avenues that have been pursued to address these problems and it will explore how alterations in material chemistry could address the detrimental impact of physico-chemical stresses on the bond formed at the adhesive/dentin interface.

Restaurações em resina composta apresentam elevada taxa de falhas, recorrência de cárie e maior necessidade de troca quando comparadas às restaurações em amálgama. A penetração de enzimas bacterianas, fluidos orais e da própria bactéria nas fendas existentes entre o dente e o compósito, enfraquecem a restauração e levam à recorrência de cárie e falhas. A margem gengival das restaurações em resina composta é particularmente vulnerável à cárie e, nesta margem, o adesivo e o selamento dentinário funcionam como a primeira bareira entre o dente preparado e o ambiente oral. O objetivo deste artigo de revisão é examinar os fatores físico-químicos que afetam a integridade e a durabilidade da interface de adesão adesivo/dentina e explorar como esses fatores agem sinergicamente para minar a restauração de resina composta. A revisão irá examinar as diversas possibilidades para solucionar esses problemas, bem como explorar como alterações na química dos materiais poderiam solucionar o impacto negativo do estresse físico-químico na interface adesiva com a dentina.