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.

Relevance of the sterilization-induced effects on the properties of different hydroxyapatite nanoparticles and assessment of the osteoblastic cell response

“…In addition, both WCS and HS particles caused a significant increase in the gene expression of the osteoblastic markers ALP and BMP-2. This is in line with previous studies showing that particulate nanoHap exhibits functional properties, namely by modulating proliferation [22] and the expression of several genes in osteoblastic cells, including collagen type I [22], ALP [21] and increasing ALP activity in periodontal ligament cells [16]. However, at high levels (500 mg ml 21 ), the presence of intracellular WCS-or HS-loaded vesicles induced alterations on the overall cell morphology, changes on the F-actin cytoskeleton and apoptotic events.…”

Nanodimensional and Nanocrystalline Calcium Orthophosphates

“…Scientists also observed enhanced osteoclast (bone-resorbing cells) functions to show healthy remodeling of bone at the simulated implant surface [177]. Besides, the proliferation and osteogenic differentiation of periodontal ligament cells were found to be promoted when a nanophase HA was used, if compared to dense HA bioceramics [188]. Thus, the underlying material property, responsible for this enhanced osteoblast function, is the surface roughness of the nanostructured surface [18].…”

Evolving application of biomimetic nanostructured hydroxyapatite

“…51 Many different methodologies have been proposed to prepare nanosized and/or nanocrystalline structures. [52][53][54][55] These are wet chemical precipitation, [56][57][58][59][60] sol-gel synthesis, [61][62][63][64] 77 and several other methods by which nanocrystals of various shapes and sizes can be obtained. [78][79][80] In general, the shape, size, and specific surface area of the apatite nanocrystals appear to be very sensitive to both the reaction temperature and the reactant addition rate.…”