Effects of Experimental Nanohydroxyapatite and Er:YAG Laser on Dentin Hypersensitivity

Objectives: This study aimed to evaluate the effects of experimental nanohydroxyapatite and Er:YAG laser on surface roughness and morphology for dentin hypersensitivity.
Methods: Dentin discs (2mm thickness) were prepared from 50 human molars and randomly divided into 5 groups (n=10): Group 1: intact dentin (positive control), Group 2: demineralized dentin (negative control), Group 3: Bifluorid 10, Group 4:.Er:YAG laser (50mJ,0.50 W, 10 Hz) Group 5: Experimental nanohydroxyapatite. Dentin hypersensitivity was simulated by 35% phosphoric acid for 1 min (except Group I). Surface roughness (Ra, mm) was measured by contact profilometry (Mahr, Marsurf PS1). Surface morphology and elemental content were evaluated by scanning electron microscopy (SEM) (Thermo Fisher Scientific, Phenom XL) and energy dispersive x-ray spectroscopy (EDS). The data were statistically analyzed using Welsch ANOVA and Games Howell. (p<0.05).
Results: Group 4 showed significantly lower surface roughness than Group 5 and Group 3 (p<0,05). Besides, no significant differences in surface roughness were found among other tested groups. (p>0.05). SEM analysis indicated that most of the dentinal tubules were obliterated for Group 5. Besides, precipitant plugs with a few partially occluded dentinal tubules were observed for Group 3 while either decreased diameter of tubules or completely occluded tubules with melting appearance were detected for Group 4. EDS analysis revealed that Ca, P and O were detected for Group 5.
Conclusions: Er:YAG laser treatment led to lower surface roughness than other treatment methods. The efficiency of nanohydroxyapatite and laser were sufficient on the dentinal tubule occlusion.