Influência de inibidores de metaloproteinases da matriz (MMPS) na resistência de união de um sistema adesivo autocondicionante em dentina hígida e erosivamente desmineralizada

Abstract

Objective: to analyze the influence of the use of two matrix metalloproteinases inhibitors [epigallocatechin-3-gallate (EGCG) and chlorhexidine digluconate (CHX)] as pretreatment solutions on dentin bond strength of a self-etch adhesive system on sound (H) and erosively demineralized dentin (ED). Materials and Methods: intact human third molars were sectioned on the occlusal third, exposing the underlying dentin surface. The surface hardness (Knoop) from exposed dentin was used as a parameter for the selection of 36 teeth that were randomly divided into 6 experimental groups according to the type and dentin pretreatment employed (n=6): HAD (sound + distilled water); HCHX (sound + 2% CHX); HEGCG (sound + 0,1% EGCG); EDAD (erosively demineralized + distilled water); EDCHX (erosively demineralized + 2% CHX); EDEGCG (erosively demineralized + 0,1% EGCG). All groups were subjected to an acquired pellicle formation with human saliva and then, teeth from EDDW, EDCHX and EDEGCG groups were subjected to an erosion cycle (1% citric acid, pH 3.75, 3 3x/day, during 5 days), whereas in the groups HAD, HCHX and HEGCG the acid solution was replaced by distilled water. Between the cycles, specimens were stored in artificial saliva for 2 h. After the cycles, dentin surfaces (sound and erosively demineralized) were pretreated with 15 μL of the solution, actively, for 60 s and than Clearfil SE Bond® (CSEB) was applied and a 4mm resin build up was made with composite resin Filtek Z250®. After storage in distilled water at 37 ºC for 24 h, specimens were sectioned in sticks, which were subjected to a which were subjected to a microtensile mechanical test with speed of 0.5 mm/min. Results: bond strength values (MPa) were statistically evaluated by two-way ANOVA (dentin condition and pretreatment) and Bonferroni test (between groups), with a significance level of 5%. The groups treated with CHX showed bond strength values statistically lower (p< 0.05) compared to the other groups, regardless of the condition of dentin. Groups with pretreatment with distilled water and EGCG showed no significant differences between them (p>0.05). Conclusion: the use of CHX influenced negatively, while the use of EGCG did not affect the bond strength of CSEB to sound and erosively demineralized dentin.