In vitro evaluation of nanohydroxyapatite synthesized from eggshell waste in occluding dentin tubules

Objectives: Dentin hypersensitivity (DH) is a notable painful condition with a negative impact on quality of life. This paper evaluates the occluding abilities of nanohydroxyapatite synthesized from the eggshell waste (EnHAp) in the treatment of DH. Methods: EnHAp was synthesized following the wet chemical precipitation method. The purity and phase change were characterized using Fourier transform infrared (FTIR) and X-ray diffraction (XRD). Field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM) were used to observe the morphology of EnHAp. The occluding capabilities were evaluated in vitro using the bovine model. Twenty-five simulated dentin specimens were randomly assigned to five groups: Group 1, untreated; Group 2, eggshell powder alone; Group 3, calcined eggshell powder; Group 4, Colgate Sensitive treated, EnHAp; and Group 5, calcium dihydrogen phosphate ( n = 5). The specimens were then subjected to remineralization protocol. The tubule occluding capabilities were observed using FESEM. Analysis of variance was used to analyze the occluding ratio values for all treated specimens. Post hoc test with Bonferroni correction was used to identify the mean differences among the five test groups (α = .05). Results: The FTIR and XRD results confirm that synthesis of EnHAp occurred. HRTEM and FESEM revealed an irregular rod structure with a particle size of 65 nm. The occluding area ratios observed for the EnHAp specimens were significantly higher than other test groups ( p < 0.001). Conclusions: The application of EnHAp resulted in an efficient occlusion of dentin tubule. This study suggests that EnHAp is an effective therapy to treat DH.