title: Effects of different pH conditions on enamel erosion repair by nano fluorapatite pastes.
abstract: The effects of different pH conditions on enamel erosion repair by nano fluorapatite (n-FA) pastes were evaluated in this study. Eighteen human dental enamel blocks with artificially-induced erosion were randomly divided into three groups that were coated with n-FA pastes with 3 different pH values (pH < 1, pH = 4.5 and pH = 7.5, respectively) for 15 minutes. SEM, XRD, XPS, Vickers microhardness test and mass measurement were performed for the enamels before and after treatment. A layer of enamel-like fluoride substituted hydroxyapatite was observed on the surface of all the samples. After treatment by n-FA pastes with 3 different pH values (pH < 1, pH = 4.5 and pH = 7.5), the Vickers micro-hardness value was respectively changed to 125.9 HV, 252.1 HV and 304.9 HV from 241.3 HV of the artificial enamel erosion, and mass loss was 0.75 mg/mm2, 0.41 mg/mm2 and 0.30 mg/mm2, respectively. SEM analysis showed that the surface of the enamels treated by n-FA pastes with pH 7.5 and pH 4.5 was smoother than those treated by n-FA pastes with pH < 1. These results suggested that the pH value had significant effects for the repairment of enamel erosion with n-FA pastes. This study demonstrated that the n-FA paste with neutral pH value (7.5) for enamel erosion repair would not only significantly enhance the enamel surface hardness, but also avoid the enamel mass loss and increased surface roughness.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Laboratory of Interdisciplinary Studies, School and Hospital of Stomatology, Peking University, Beijing 100081, China.
authors.forename: Chengjie
authors.initials: C
authors.lastname: Wang
authors.forename: Yifei
authors.initials: Y
authors.lastname: Zhang
authors.forename: Jie
authors.initials: J
authors.lastname: Wei
authors.forename: Shicheng
authors.initials: S
authors.lastname: Wei
mesh_terms: D001031:Apatites; D003743:Dental Enamel; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles; D014961:X-Ray Diffraction
chemical_list: D001031:Apatites; C025105:fluorapatite