Micromorphology and adhesive performance of Er:YAG laser-treated dentin of primary teeth

Abstract

This study evaluated (1) the micromorphology by scanning electron microscopy (SEM) and (2) the adhesive performance by microtensile bond strength (μTBS) of diamond bur-treated dentin compared to Er:YAG laser-treated dentin of human primary teeth. (1) For qualitative SEM evaluation, dentin of 18 second primary molars (n = 3/method) was treated with either diamond bur as a control (group 1a: 40 μm diamond bur only (clinical situation); group 1b: grinding + 40 μm diamond bur) or with Er:YAG laser (group 2a (clinical situation, manufacturer's settings): 200 mJ/25 Hz (5 W) + 100 mJ/35 Hz (3.5 W) laser only; group 2b (experimental setting "high"): grinding + 400 mJ/20 Hz (8 W); group 2c (manufacturer's setting "finishing"): grinding + 100 mJ/35 Hz (3.5 W); group 2d (experimental setting "low"): grinding + 50 mJ/35 Hz (1.75 W)). (2) For evaluation of adhesive performance, 64 second primary molars were divided into four groups and treated as described for group 1b and groups 2b/c/d (n = 16/method), and μTBS of Clearfil SE/Clearfil Majesty Esthetic to dentin was measured. The SEM micrographs were qualitatively analyzed. The μTBS values were compared with a Kruskal-Wallis test. The significance level was set at α = 0.05. SEM micrographs showed the typical micromorphologies with a smear layer for the diamond bur groups and open dentin tubules for all laser-treated groups. However, in group 2d, the laser beam had insufficiently irradiated the dentin area, rendering the underlying ground surface partly visible. There were no statistically significant differences between μTBS values of the four groups (p = 0.394). This suggests that Er:YAG laser treatment of dentin of primary molars provides bond strengths similar to those obtained following diamond bur treatment.

Effects of Er:YAG Laser on Mineral Content of Sound Dentin in Primary Teeth

“…They observed no carbonization or cracks, and the SEM micrographs were similar to those of permanent teeth. Flury et al [37] compared the dentinal morphology of primary teeth using an Er:YAG laser and a diamond bur, and they reported open dentin tubules for all the laser-treated groups. These results were in accordance with our findings; we observed open dentin tubules for both laser groups when compared to the control group.…”

“…The same parameters of Er:YAG laser in primary teeth have not been studied yet. However, similar power setting of Er:YAG laser in primary teeth was used in a few studies [12, 13, 37, 38]. Zhang et al [13] reported that laser power of less than 4 W at Er:YAG laser should be used for cavity preparation in primary teeth.…”

The Effect of Er:YAG Laser Irradiation and Different Concentrations of Sodium Hypochlorite on Shear Bond Strength of Composite to Primary Teeth’s Dentin

“…According to the results of the current study, the mean shear bond strength in the groups prepared by laser was slightly higher than the groups prepared by bur, although the difference was not statistically significant and was in agreement with the results of the previous studies. 33,34 This little increase in shear bond strength in groups prepared by laser is probably due to the morphologic properties of the surface after preparation by laser. 35 In the present study, the application of sodium hypochlorite with different concentrations did not show a statistically significant increase in mean shear bond strength compared with the other groups without application of sodium hypochlorite, which was consistent with the results of the study conducted by Gowda et al They reported that using 10% sodium hypochlorite can completely remove the smear layer, and higher concentrations can decrease the application time.…”

Cavity Preparation by Laser in Primary Teeth: Effect of 2 Levels of Energy Output on the Shear Bond Strength of Composite Restoration to Dentin

“…[14][15][16][17][18][19][20][21] Some other results have reported no difference in the bond strength or leakage of adhesive restorations between bur and laser prepared restorative cavities. [22][23][24][25] At different laser parameters, different amount of tooth ablation and thermo-chemical changes occur on tooth surfaces, resulting in different performances from the same adhesives. Laser energy is one of the most important parameters affecting the characteristics of the prepared surface.…”