Effect of Er, Cr: YSGG, Nd: YAG, and diode laser against different photosensitizers on tensile and shear bond strength of bonded composite to caries affected dentin.

OBJECTIVE: This study aimed to assess the impact of various cavity disinfection methods on the adhesive bond integrity of composite resin to caries-affected dentin (CAD). Additionally, it will evaluate the micro tensile bond strength (µTBS) of different dentin substrates [CAD and sound dentin (SD)] using various adhesive agents.

MATERIALS AND METHODS: The sample consisted of twenty human mandibular molars with sound dentin (SD) and eighty with CAD. All samples were positioned in a group of polyvinyl pipes with an internal diameter of 3 mm and were positioned perpendicularly up against the cementoenamel junction (CEJ). A total of 60 CAD samples (n=10) were used for shear bond strength (SBS) testing. CAD samples were disinfected with erbium chromium-doped yttrium, scandium, gallium and garnet (Er, Cr: YSGG) laser in group 1, Diode laser in group 2, neodymium-doped yttrium aluminum garnet (Nd: YAG) laser in group 3, riboflavin in group 4, curcumin in group 5, and chlorhexidine in group 6. Sixty CAD samples were treated with Scotchbond™ Etchant and Scotchbond™ multi-purpose primer and bonded with composite for SBS testing. On the twenty remaining CAD samples that did not undergo any type of disinfection, as well as the twenty samples that had sound dentin (SD), two different types of adhesive systems were used for micro tensile testing. For ten of each CAD and SD sample, 3c™ Adper™ Scotchbond™ multi-purpose adhesive was applied to the dentin surfaces. For the remaining ten CAD and SD samples, the All-Bond 2 adhesive system was used. The samples were prepared for µTBS testing. In all specimens, bond failure was assessed using a stereomicroscope. Analysis of variance (ANOVA) and Tukey Honestly Significant Difference (HSD) tests were used to compare the means of multiple groups, at a significance level of p<0.05.

RESULTS: CAD disinfected with chlorhexidine (CHX) (17.19±1.02 MPa) exhibited the highest SBS values. Samples in group 5 disinfected with curcumin activated by photodynamic therapy (PDT) showed the lowest SBS (12.49±1.11 MPa). Scotchbond adhesive displayed comparable µTBS (p>0.05) when applied on CAD and SD. Moreover, All-Bond 2 adhesive, when applied on CAD, exhibited µTBS significantly lower than All-Bond 2 adhesive on SD (p<0.05). Analysis of debonded CAD surface after SBS showed that a cohesive type of failure was dominant in different experimental groups, followed by adhesive CONCLUSIONS: CAD disinfection with Er:Cr: YSGG, Diode Laser, and Riboflavin activated by photodynamic therapy have the potential to be used as an alternative to CHX for acceptable shear bond strength. The use of Adper™ Scotchbond™ multi-purpose adhesive on CAD and SD did not significantly compromise µTBS.