Effect of 1% chlorhexidine gel on the bonding strength to dentin

Abstract

Background/purpose: The purpose of this in vitro study was to evaluate the effect of 1% chlorhexidine (CHX) gel on dentin bond strengths of posterior composite resin applied with two different adhesive systems. Material and methods: In total, 75 extracted, caries-free human molars were used. The occlusal surface of each tooth was ground to create a flat dentin surface. Then, each tooth was mounted in acrylic. The dentin specimens were randomly assigned to five groups of 15 specimens each. In Group 1, Prime Et Bond NT (PBNT) was applied; in Group 2, a 1% CHX gel + etching for 15 s + PBNT were applied; in Group 3, etching + 1% CHX gel + PBNT were applied; in Group 4, Clearfil S-3 Bond was applied; and in Group 5, 1% CHX gel + Clearfil S-3 Bond were applied. A dentine bonding system was applied to dentin surfaces, and composite cylinders were built up using a special device and then light-polymerized. Specimens were mounted and sheared using an Instron universal testing machine at a cross-head speed of 0.5 mm/min. Results: The results were recorded in megapascals. The sheared specimens were examined under a light microscope, and the type of failure (adhesive, cohesive or mixed) was recorded. Data were compared by one-way analysis of variance and Tukey's honestly significant difference tests. Means were 16.4 +/- 4.1 MPa in Group 1, 16.2 +/- 3.9 MPa in Group 2, 13.0 +/- 4.5 MPa in Group 3, 11.9 +/- 2.7 MPa in Group 4, and 11.5 +/- 2.7 MPa in Group 5. The use of 1% CHX gel before acid etching was significantly higher than after etching on the shear bond strength of PBNT (P < 0.05), but did not differ significantly from PBNT alone (P > 0.05). Conclusion: Within the limitations of the present in vitro study, it was concluded that 1% CHX gel application did not adversely affect the shear bond strengths of dentin-bonding agents.