title: Comparison of periodontal ligament cells responses to dense and nanophase hydroxyapatite.
abstract: Hydroxyapatite, a synthetic calcium phosphate ceramic, is used as a biomaterial for the restoration of human hard tissue as well as in techniques which aim to regenerate periodontal tissues. Generally, hydroxyapatite is believed to have osteoconductive effects and to be non-bioresorbable but not to induce to periodontal tissue regeneration. No report has been found on responses of periodontal ligament cells (PDLC), the main contributor to periodontal tissue regeneration, to nanoparticles of hydroxyapatite. The objective of this study was to investigate the possible effects of nanophase powder of hydroxyapatite on proliferation of periodontal ligament cells. Using a sol-gel method, the nanophase hydroxyapatite powders were fabricated. These powders were proved to comprise nanoparticles by transmission electron microscope examination. The primary periodontal ligament cells were cultured on dense particle hydroxyapatite and nanometer particle hydroxyapatite. The effects on proliferation of periodontal ligament cells on dense and nanoparticle hydroxyapatite were examined in vitro using a methyl thiazolil tetracolium (MTT) test. The intercellular effects were studied with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray (EDX). In addition, the influence of the two materials on osteogenic differentiation was determined through measurement of alkaline phosphatase activity and flow cytometry. About 2, 3, and 4 days after treatment with nanoparticles of hydroxyapatite, the proliferation activity of the PDLC increased significantly compared with those proliferating on dense hydroxyapatite and of control PDLC, but no significant difference was found between the PDLC proliferation on dense hydroxyapatite and the control PDLCs. After 3 and 5 days' incubation with nanoparticles of hydroxyapatite, alkaline phosphatase activity was significantly increased as compared to PDLCs incubated with dense hydroxyapatite and control PDLCs. Intracellular engulfment was found in the cultured cells with nanophase hydroxyapatite under electron microscopy. The results suggest that nanophase hydroxyapatite can promote proliferation and osteogenic differentiation of periodontal ligament cells and further that it may be used as a bioresorbable agent in osseous restoration.
authors.affiliation: Department of Periodontology, College of Stomatology, Nanjing Medical University, Nanjing, PR China. wbsun@njmu.edu.cn
authors.forename: Weibin
authors.initials: W
authors.lastname: Sun
authors.forename: Chenlin
authors.initials: C
authors.lastname: Chu
authors.forename: Juan
authors.initials: J
authors.lastname: Wang
authors.forename: Huating
authors.initials: H
authors.lastname: Zhao
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D001672:Biocompatible Materials / Q000737:chemistry / Q000494:pharmacology*; D002478:Cells, Cultured; D017886:Durapatite / Q000737:chemistry / Q000494:pharmacology*; D016557:Guided Tissue Regeneration, Periodontal; D006801:Humans; D066298:In Vitro Techniques; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D049329:Nanostructures / Q000737:chemistry; D010513:Periodontal Ligament / Q000166:cytology* / Q000187:drug effects* / Q000201:enzymology; D013057:Spectrum Analysis; D014965:X-Rays
chemical_list: D001672:Biocompatible Materials; D017886:Durapatite; D000469:Alkaline Phosphatase