Efeito de inibidores de metaloproteinases e da temperatura de volatilização na resistência de união de restaurações adesivas

Abstract

Even with the advance of dental materials and techniques, adhesive restorations have long term limitations. The aim in this study was to evaluate the effect of dentin pretreatment with metalloproteinase inhibitors (chlorhexidine 2% - CHX and glutaraldehyde 5% - GD) and the volatilization temperature (23 and 40ºC) of the solvent of the adhesive system on bond strength (BS) of adhesive restorations after 24 h and aging. Thirty-six sound human third molars were collected (CAAE 73605617.4.0000.5515), the teeth had coronary dentin of medium depth exposed, then the acid conditioning was performed, followed by dentin pretreatment with distilled water (control), CHX (Clorhexedina, Villevie) or GD (Gluma, Heraeus Kulzer). In the end, the adhesive system was applied by total acid etching technique, volatilized at 23 or 40ºC, and light cured to posterior confection of a composite resin block. The specimens were cut in 0.8 x 0.8 mm sticks, half of the sticks were evaluated after 24 h and the other half was evaluated after aging (10,000 thermal cycles and 4 weeks of storage in 0.2% collagenase). BS (n = 6) was obtained by the microtensile test using a universal test machine. Data were analyzed by tree-way ANOVA for repeated measures and Bonferroni test ( = 0.05). Dentin pretreatment using GD showed higher BS (55.03  7.19 MPa) compared to distilled water (49.18  7.23 MPa), and chlorhexidine pretreatment showed intermediate BS value (51.89  6.70 MPa). Volatilization of adhesive at 40ºC increased BS (53.32  7.23 MPa) compared to 23ºC (50.46  7.27 MPa). After thermal cycling and collagenase storage the BS was reduced (50.23  7.72 MPa) compared to 24 h (54.04  6.62 MPa). Aging decreased the BS, but dentin pretreatment using GD and the use of warm air stream for solvent volatilization were effective for improvement of BS of dental adhesive restorations.