Collagen synthesis from human PDL cells following orthodontic tooth movement

Abstract

The dynamic remodelling processes in the periodontal ligament (PDL) account for the reaction of PDL cells to different orthodontic force simulations. These occur mostly by degradation and synthesis of collagen types I, III, V, VI, XII and XIV. The purpose of this study was to quantify specific collagen types in the PDL from zones of tension and compression of experimental teeth. Such changes could then be correlated with the processes of orthodontic-stimulated tissue breakdown. Maxillary and mandibular premolars of three females and one male patient were orthodontically moved with a box loop for a total of 14 days, prior to tooth extraction. Teeth from the contralateral side of either the maxilla or the mandible served as the untreated controls. A total of seven experimental and seven control teeth were used in this investigation. PDL fibroblasts from the cervical third of the roots corresponding to the compression and tension zones of the experimental and control teeth, respectively, were scraped and cultured in vitro at 37 degrees C in a humidified incubator with 5 per cent CO2/95 per cent air. Collagen synthesis of types I, III, V and VI was quantified by using an ELISA. Application of orthodontic forces in the experimental teeth showed a significant increase (P < 0.05) of the synthesis of all collagen types in the compression as opposed to the tension zones. Collagen synthesis on the compression zone of experimental teeth was not significantly different in the mandible when compared with those of the maxilla. In addition, the proportional distribution of different types of collagen was also not significantly different in the PDL fibroblasts from either zone of experimental teeth of either the maxilla or the mandible. Collagen metabolism in response to orthodontic stimulation appears to be higher in the compression zones and lower in the tension zones. Contrary to what is traditionally assumed in the literature, such findings indicate that in addition to bone resorption, tissue remodelling is very active in zones of compression following the disappearance of the hyalinized areas. These findings constitute a model for future studies on collagen metabolism during orthodontic-stimulated tooth movement.

Effects of human relaxin on orthodontic tooth movement and periodontal ligaments in rats

“…35 Interestingly, an increase in collagen synthesis during tooth movement on the compression side also has been documented. 36 At first, the latter might seem contradictory, but it is possible that total collagen turnover is increased at compression sites with a net loss due to an imbalance between synthesis and degradation. It was also suggested that 4% stretching of PDL fibroblasts results in a dramatic increase of type I collagen gene expression.…”

Effects of compressive stress on the expression of M-CSF, IL-1β, RANKL and OPG mRNA in periodontal ligament cells

“…Furthermore, it was reported that inflammatory cytokines, such as PGE2, IL-1α, IL-1β, IL-6 and TNF-α, are produced by mechanically stimulated PDL cells. [11][12][13] Previous reports showed that PDL cells can participate in osteoclastogenesis but the production of the related cytokines in PDL cells has not been fully characterized. In particular, for M-CSF and IL-1β, their production in mechanically stimulated PDL cells has not been documented.…”

Cadherin-11 modulates cell morphology and collagen synthesis in periodontal ligament cells under mechanical stress

“…12,13 During orthodontic tooth movement, PDL collagen is degraded in the compression region, with altered expression of type I collagen (Col-I) and cytoskeleton of cells. 14,15 Hence, the present study aimed to test the hypothesis that cadherin-11 is expressed in PDLCs and modulates cell morphology and collagen synthesis in PDLCs in response to mechanical stress.…”