Laser Effect on Bond Strength of a Self-adhesive Flowable Composite

Objective: The aim of this in vitro study was to evaluate the effect of laser treatment on shear bond strength of a self-adhesive flowable resin composite to human dentin.

Method: Eighty extracted sound human molar teeth were used for the study. After the teeth were sectioned mesiodistally, they were embedded in acrylic blocks. The dentin surfaces were wet ground with 600-grit silicone carbide(SiC) paper. The teeth were randomly divided into 2 treatment groups; laser(Er:YAG laser, 12 Hz, 350mJ) and control(SiC). Each group was then divided into 2 subgroups according to the flowable resin composite type; a self-adhering, Vertise Flow and a conventional, Premise Flow with Optibond Solo Plus(n=20). Flowable composites were applied according to the manufacturer’s recommendations using Ultradent method for shear bond strength test. The bonded specimens were stored in water for 24 hours, and bond strength was tested at 1 mm/min. The debonded surfaces were observed under a microscope to determine the main failure mode. The bond strength data were analyzed using 2-way ANOVA and Student Newman test. Failure mode data were analyzed using ANOVA on ranks(p<0.05).

Results: The self-adhesive flowable resin, Vertise Flow showed significantly higher bond strength values to laser-treated surfaces than to SiC-treated surfaces(p<0.001). Premise Flow produced similar bond strength values for SiC- and laser-treated surfaces. While there was a significant difference between flowables in SiC-treated surfaces(p<0.001), no difference was observed in laser-treated surfaces(p=0.053). No significant differences were observed on failure mode(p=0.303)(Table 1).

Table I. Mean Shear Bond Strengths (MPa) and Standard Deviations

SurfaceTreatment	Flowable resin composites	Shear bond Strength(MPa)	Standard Deviation(SD)
Laser	Premise Flow	16.81	6.75
	Vertise Flow	12.61	2.91
SiC	Premise Flow	14.64	6.76
	Vertise Flow	7.92	3.49

 

Conclusion: The bond strength of a self-adhesive flowable composite differs according to the type of dentin surface treatment. Laser treatment increased the dentin bonding values of self-adhesive flowable composite.