Quantitative and qualitative evaluation of resin-dentin bond strengths: in vitro effects of surface treatment with metalloproteinase inhibitors

AIM: The objective of this study was to evaluate the use of MMPs inhibitors (chlorhexidine and EDTA) in bond strength and quality of the hybrid layer of adhesive restorations in normal dentin using two ethanol-based total-etch adhesive systems. MATERIAL AND METHODS: Thirty-two extracted human molars were coronally sectioned and randomly divided into 8 groups (n=4), depending on the surface pre-treatment and adhesive system used. The total-etch adhesive systems Single Bond 2 (2-step) and Adper Scotchbond Multi-Purpose Plus (3-step) were used as follows: 1) according to manufacturer's instructions (etching with 37% phosphoric acid (H3PO4) for 15 s); 2) etching with H3PO4 for 15 s, followed by 2% chlorhexidine for 120 s; 3) etching with 0.1 M EDTA for 60 s; 4) etching with 0.1 M EDTA followed by 2% chlorhexidine for 120 s. Teeth were incrementally restored with composite resin (Filtek Z350XT). After water storage for 24 h, teeth were double-sectioned, yielding stick specimens of 1.0 mm² bonded area, and then subjected to microtensile bond strength (MTBS) test at 0.5 mm/min. Additional specimens were gold-sputtered to be analyzed under scanning electron microscopy (SEM). Data (in Mega Pascal) were subjected to Kruskal-Wallis and Dunn (p <0.05) tests. RESULTS: The etching protocol (37% H3PO4 or EDTA) interfered with hybrid layer formation, monomer penetration and the MTBS. Funnel shaped resin tags were observed when dentin was etched with 37% H3PO4. In these specimens, MTBS were also higher. EDTA conditioning produced thin hybrid layers and smaller MTBS, regardless the adhesive system used. Chlorhexidine application after conditioning resulted in no apparent differences between both evaluated techniques (37% H3PO4 or EDTA). CONCLUSION: The use of chlorhexidine as a MMP inhibitor does not alter immediate bond strength values and does not interfere with hybrid layer formation.

Clareamento dental interno / Intra coronal bleaching

Atualmente, um dos aspectos mais estimados no conjunto estético da face é o sorriso. Este fato estimulou o desenvolvimento de técnicas e materiais que proporcionem um resultado mais harmonioso, que satisfaça os anseios do paciente. Antigament, dentes que apresentavam anomalias de cor recebiam desgastes para, em seguida, serem reconstruídos através de procedimentos diretos ou indiretos. Hoje, o profissional pode contar com técnicas altamente eficazes e seguras que possibilitam a reversão destes quadros de alteração de cor. O clareamento é a tentativa mais conservadora de restabelecer a cor normal dos dentes, através da descoloraçã das manchas dentais por processos de oxidação ou redução. Sendo assim, o objetivo deste trabalho é elucidar, através de uma revisão de literatura, as principais técnicas e procedimentos necessários para o clareamento de dentes não vitais.