Abstract
The aim of this study was to evaluate the effect of Er:YAG laser irradiation on the micro-shear bond strength of self-etch adhesives to the superficial dentin and the deep dentin before and after thermocycling. Superficial dentin and deep dentin surfaces were prepared by flattening of the occlusal surfaces of extracted human third molars. The deep or superficial dentin specimens were randomized into three groups according to the following surface treatments: group I (control group), group II (Er:YAG laser; 1.2 W), and group III (Er:YAG laser; 0.5 W). Clearfil SE Bond or Clearfil S3 Bond was applied to each group’s dentin surfaces. After construction of the composite blocks on the dentin surface, the micro-shear bond testing of each adhesive was performed at 24 h or after 15,000 thermal cycles. The data were analyzed using a univariate analysis of variance and Tukey’s test (p < 0.05). Laser irradiation in superficial dentin did not significantly affect bond strength after thermocycling (p > 0.05). However, deep-dentin specimens irradiated with laser showed significantly higher bond strengths than did control specimens after thermocycling (p < 0.05). Thermocycling led to significant deterioration in the bond strengths of all deep-dentin groups. The stable bond strength after thermocycling was measured for all of the superficial-dentin groups. No significant difference was found between the 0.5 and 1.2 W output power settings. In conclusion, the effect of laser irradiation on the bond strength of self-etch adhesives may be altered by the dentin depth. Regardless of the applied surface treatment, deep dentin showed significant bond degradation.
Highlights
The basic mechanism of adhesion between tooth substrate and adhesive bonding agents is based on an exchange process
No significant difference was found between the bond strengths of adhesive agents in each laser group (Group II and III), regardless of testing time and dentin type
The laser irradiation did not statistically affect the bond strength of Clearfil SE Bond to the superficial dentin when compared to the control group at 24 h, but the bond strength to deep dentin improved
Summary
The basic mechanism of adhesion between tooth substrate and adhesive bonding agents is based on an exchange process. Minerals from the hard tissues of teeth are replaced by adhesive monomers that effectively create a micromechanical interlock after polymerization [1]. Before the bonding agent is applied, the standard procedure for better bonding is the etching of enamel with phosphoric acid [2]. The moist and organic nature of dentin has prevented the development of a reliable, durable resin-dentin bonding. Bonding stability to dentin depends on the formation of a homogenous and compact hybrid layer. The degradation of the dentin-bonding interface is caused by hydrolysis and proteolytic breakdown of the collagen fibril components of the hybrid layer or by hydrolytic degradation of the hybrid layer’s adhesive components [3, 4]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
