Collagen turnover in the periodontal ligament under normal and altered functional forces

Abstract

48 six month old rats were given 1 μCi/g of body weight of tritiated proline by intraperitoneal injection, 24 of them having had the left maxillary molars extracted two weeks earlier; 4 animals from each group were killed after a further 12 hours, 1, 4, 7, 12 or 20 days. Analyses of autoradiographic grain densities in various areas of the lower first molar periodontal ligament allowed calculation of half‐lives which were attributable to collagen turnover; all such values were less than 12 days. It is argued that the results are applicable to man in relative terms and thus have several important clinical implications. It becomes entirely feasible that the tissue destruction in chronic periodontitis is, at least in part, a function of decreased collagen formation brought about by any inflammatory process. The normal relatively slow rate of turnover in crestal fibres may well provide a barrier to the spread of inflammation from the gingiva, but its increase consequent on incresed tooth movement, as occurs in active orthodontic treatement, may reduce the barrier's effectiveness. However, the turnover rate is such taht even in adults it should not be a limiting factor in orthodontic treatement or in periodontal treatment aimed at restorring attachement.

Age‐related alterations of periodontal structures around the cemento‐enamel junction and of the gingival connective tissue composition in germ‐free rats

“…Schneir et al (1976) examining the palatal antemolar mucosa in rats between 17 and 680 days of age found an age-dependent decrease in the rate of collagen synthesis. For 42-day old rats, Rippin (1976) demonstrated a high turnover of collagen in the crestal portion of the periodontal ligament, a site which is topographically close to the supraalveolar attached gingiva portion. The present data suggest that fibroblasts residing in this supraalveolar attached portion of the gingiva, although remaining constant in number over the age period from 30 to 80 days, are maximally large around the age of 40 days, at least in the facial and interdental gingiva, but furtheron decrease in size considerably.…”

Collagen Phagocytosis by Fibroblasts in the Periodontal Ligament of the Mouse Molar During the Initial Phase of Hypofunction

“…This inference is in accordance with the work of Kanoza et al (1980), who found that in the rat periodontal ligament the rate of synthesis and deposition of collagen doubled three days after extraction of the opposing molars. Also, Rippin (1976Rippin ( , 1978, in a radioautographic study of overall protein turnover in periodontal ligaments from normal and hypofunctional rat molars, noted an increase of turnover in the crestal portion of the latter.…”

The extracellular matrix of the periodontium: dynamic and interactive tissues

“…The metabolic activity of the periodontal ligament also seems to depend on location. The areas adjacent to the alveolar bone have a rapid turnover (77, 93, 1661, and collagen half-lives differ between the apical and crestal regions of the periodontal ligament (116,126,127). The rate of turnover of the different collagen types is not known, but studies have demonstrated that the metabolism of types I and I11 collagen appears to be similar (158,159).…”