[Electron microscopic study on calcification of porous hydroxyapatite ceramics implanted in the submandibular glands of rats].
This study was primarily designed to determine the tissue responses and the initial calcification profiles after the implantation of porous hydroxyapatite ceramics (HAP), and secondly, to find out the effects of chronic isoproterenol (IPR) administration on them. For the experiment 1, several granules of HAP were implanted in the submandibular glands of rats and for another experiment 2, chronic IPR administration was carried out to rats implanted HAP. The surrounding tissues of HAP implanted and the insides of its pores were observed and analyzed with a light microscope, an electron microscope and an analytical electron microscope one and three days, and five, eight and ten weeks after treatment. The results were as follows: 1. The outer layer of HAP was encapsulated by granulation tissues due mainly to the infiltration of inflammatory cells one and three days after treatment. Subsequently, the encapsulation was further enhanced by fibrous cells and collagen fibers, whereas no obstructive reactions were seen in the surrounding tissues of HAP implanted. 2. From the first day after treatment, tissue fluid-like matrix substances permeated inside HAP and at the same time, blood cells, phagocytic and mesenchymal cells were detected within the whole HAP. 3. Especially, in the layer within 100-200 microns inside the pores of HAP, a number of fibroblasts, collagen fibers and osteoblast-like cells were observed. 4. Within the pores with cells infiltrated into HAP, a layer, suggestive of the precipitation of calcium-phosphate salts, was formed from one week after treatment. By five weeks, particularly within the layer, amorphous substances with the high density were observed in general and, by eight and ten weeks, the substances were further increased in thickness. 5. By eight and ten weeks, amorphous substances with the high density were observed in a line with collagen fibers and around the cells within HAP. 6. The amorphous substances with the high density were calcified substances consisting of mainly Ca and P, as observed by an elemental analysis. 7. By administration of IPR, most of the acinar cells and the cells in the pores became degenerative after about five weeks and less calcified substances were observed along the collagen fibers. However, as seen in the experiment 1, calcified substances were also found in the precipitated layer within matrix-like substances of the pores.(ABSTRACT TRUNCATED AT 400 WORDS)
Morimitsu
T
T
Graduate School of Dentistry, The First Department of Conservative Dentistry, Fukuoka Dental College.
D000818:Animals; D002114:Calcinosis / Q000139:chemically induced*; D006882:Hydroxyapatites / Q000009:adverse effects*; D007545:Isoproterenol / Q000633:toxicity; D008854:Microscopy, Electron; D016062:Porosity; D019736:Prostheses and Implants / Q000009:adverse effects*; D051381:Rats; D011919:Rats, Inbred Strains; D013363:Submandibular Gland / Q000187:drug effects / Q000473:pathology / Q000648:ultrastructure*
D006882:Hydroxyapatites; D007545:Isoproterenol