Dentin Sealing and Bond Strength Evaluation of Hema-Free and Multi-Mode Adhesives to Biomodified Dentin

Abstract This study evaluated the effect of dentin biomodification on the bond strength (BS) and sealing ability (SA) of HEMA-free and multi-mode adhesives after 24 h and 6 months of water storage. Four adhesives were tested: two multi-mode (Scotchbond Universal - SU, and Prime & Bond Elect - PB) and two HEMA-free (All-Bond 3 - AB, and G-Aenial - GA). Human third molars were selected and dentin was treated with two cross-linking agents (5% glutaraldehyde and 6.5% proanthocyanidin-rich grape seed extract - PACs) for 10 min or kept untreated (control group) (n=6). Teeth were sectioned and prepared for BS test and SA analysis. The SA measurements were taken with the presence of smear layer (minimum permeability), EDTA treatment (maximum permeability), PACs application, adhesive application and after 6 months of water storage. BS data were analyzed by Proc Mixed and Tukey-Kramer test (α=5%). PACs application increased the BS for all adhesives tested at 24 h. However, BS decreased for SU and AB after six months. In general, multi-mode adhesives (SU and PB) did not differ from AB HEMA-free. GA presented the lowest BS values at both times of evaluation. Dentin permeability was reduced after PACs application and remained the same after 6 months, regardless adhesive application. PACs can increase the BS regardless the type of adhesive, however only for PB and GA the BS kept stable after 6-months of water storage. PACs was able to seal the dentin as the minimum permeability and also remained stable after 6 months.

Resumo Este estudo avaliou o efeito da biomodificação da dentina na resistência de união (BS) e capacidade de selamento (SA) de adesivos "HEMA-free" e "multi-mode" após 24 horas e 6 meses de armazenamento em água. Quatro adesivos foram testados: dois "multi-mode" (Scotchbond Universal - SU, e Prime & Bond Elect - PB) e dois "HEMA-free" (All-Bond 3 - AB, e G-Aenial - GA). Terceiros molares humanos foram selecionados e a dentina desses dentes foi tratada com dois agentes "cross-linking" (glutaraldeído 5% e extrato de uva contendo proantocianidina 6.5% - PACs) por 10 min ou permaneceram sem tratamento (grupo controle) (n=6). Os dentes foram seccionados e preparados para teste de BS e análise de SA. As mensurações de SA foram adquiridas com a presença de "smear layer" (mínima permeabilidade), tratamento com EDTA (máxima permeabilidade), aplicação dos PACs, aplicação de adesivo e após 6 meses de armazenamento em água. Os dados de BS foram analisados pelo Proc Mixed e teste de Tukey-Kramer (α=5%). A aplicação dos PACs aumentaram a BS para todos os adesivos testados no tempo de 24 h. Entretanto, a BS reduziu para o adesivo SU e AB após 6 meses. Em geral, os adesivos "multi-mode" (SU e PB) não diferiram do AB "HEMA-free". O adesivo GA apresentou o menor valor de BS em ambos tempos de avaliação. A permeabilidade dentinária foi reduzida após a aplicação dos PACs e permaneceu a mesma até 6 meses, independente da aplicação do adesivo. Os PACs podem aumentar a BS independente do tipo de adesivo, entretanto somente para o adesivos PB e GA a BS manteve estável após 6 meses de armazenamento em água. Os PACs foram capazes de selar a dentina como a permeabilidade mínima da dentina, que permaneceram estável após 6 meses.

Effects of matrix metallproteinases on dentin bonding and strategies to increase durability of dentin adhesion

The limited durability of resin-dentin bonds severely compromises the longevity of composite resin restorations. Resin-dentin bond degradation might occur via degradation of water-rich and resin sparse collagen matrices by host-derived matrix metalloproteinases (MMPs). This review article provides overview of current knowledge of the role of MMPs in dentin matrix degradation and four experimental strategies for extending the longevity of resin-dentin bonds. They include: (1) the use of broad-spectrum inhibitors of MMPs, (2) the use of cross-linking agents for silencing the activities of MMPs, (3) ethanol wet-bonding with hydrophobic resin, (4) biomimetic remineralization of water-filled collagen matrix. A combination of these strategies will be able to overcome the limitations in resin-dentin adhesion.