EFFECT OF OLEIC ACID ETCHANT ON RESIN DENTIN BONDING: MONOMER PENETRATION AND STABILITY OF DENTIN COLLAGEN

Abstract

Background: The durability of resin dentin bonds is critical for the long term success of dental restorations. Traditional acid etching techniques, particularly with phosphoric acid, have been widely used to improve bond strength by demineralizing dentin and exposing collagen fibrils. This study investigates the effects of oleic acid on resin dentin bonding, specifically focusing on monomer penetration and the stability of dentin collagen.

Objectives: The primary aim of this study was to evaluate the effect of oleic acid as an etching agent on resin dentin bonding. Specifically, the study assessed (1) the depth of resin monomer penetration into the dentin matrix and (2) the stability of dentin collagen after oleic acid etching, compared to traditional phosphoric acid etching and untreated dentin.

Methods: Human molar teeth were sectioned to expose flat dentin surfaces and randomly divided into four groups: (1) untreated dentin control, (2) phosphoric acid etching 37 percent, (3) oleic acid etching 5 percent, and (4) oleic acid etching with collagen cross linking agent glutaraldehyde. Resin adhesive Clearfil SE Bond was applied to the dentin surfaces, followed by composite resin placement. Monomer penetration was evaluated using confocal laser scanning microscopy CLSM, and collagen stability was assessed by incubating specimens in collagenase solution, followed by histological analysis using Sirius Red staining. Microtensile bond strength testing was performed to measure bond strength.

Results: Monomer penetration was significantly deeper in the phosphoric acid group 250 um compared to the oleic acid group 180 um. The oleic acid plus cross linking group showed slightly improved penetration 200 um. Collagen stability was notably better in the oleic acid and oleic acid plus cross linking groups, with significantly less degradation observed after collagenase treatment compared to the phosphoric acid group. Microtensile bond strength testing revealed higher bond strength in the phosphoric acid group 30 MPa, followed by the oleic acid plus cross linking group 25 MPa, oleic acid alone 22 MPa, and untreated dentin 10 MPa.

Conclusion: These findings suggest that oleic acid may offer long term benefits by enhancing collagen preservation, though further studies are needed to optimize its application and understand its clinical implications.