Effect of the Er: YAG laser on the shear bond strength of conventional glass ionomer and Biodentine™ to dentine

OBJECTIVES: The purpose of this study was to determine if Er: YAG laser etching improves the shear bond strength (SBS) of Biodentin™ and GC Fuji IX(®) to dentine. MATERIALS AND METHODS: Forty human dentine specimens were standardized and embedded in stone. The specimens were randomized into four groups (n = 10). Twenty samples were treated with the Er: YAG laser radiation and 10 of these restored with GC Fuji IX(®) and 10 with Biodentine™. The remaining 20 specimens acted as controls (no laser treatment); 10 were restored with GC Fuji IX(®) and 10 with Biodentin™. All samples were then stored in an incubator at 37.5°C and 100% humidity for 7 days. The SBS was determined using a Zwick universal testing machine. A two-way analysis of variance test was used to evaluate the statistical difference in SBS between the groups. An independent sample t-test was used to determine the statistical significance of differences between control and lased groups within the same material. RESULTS: A highly statistically significant difference in SBS was found with the laser treatment (P = 0.0001) and material (i.e., Biodentin™ or Fuji IX(®) (P = 0.0001). The GC Fuji IX(®) group recorded the highest mean SBS required to dislodge the material from the laser-treated dentine surface (1.77 ± 0.22 Mega-Pascal [MPa]). The mean SBS of Biodentin™ to dentine following the laser radiation (1.12 ± 0.16 MPa) was significantly greater compared to the nonlased dentine (0.53 ± 0.09). Pearson Chi-square test indicated a nonsignificant relation between shear strength and mode of failure (P = 0.467). CONCLUSION: Laser etching of the dentine surfaces yielded a significant increase in the bond strength for both GC Fuji IX(®) and Biodentin™. The SBS of Biodentin™ to dentine is greater than with conventional glass ionomer (Fuji IX(®)).