Formation of a new fibrous attachment to human dental roots

Summary

Human periodontal ligament cells have been shown to produce a new fibrous attachment at the surface of scaled dental root discs in vitro. The purpose of this investigation was to answer the question whether cells derived from human alveolar bone would enhance this attachment. Three partially erupted third molars were extracted and collected from one female patient and used for harvesting periodontal ligament cells as well as for cutting 0.3 mm dental root discs. Cells derived from alveolar bone were obtained by enzymatic digestion of bone chips harvested after extraction of wisdom teeth from three additional patients. Experimental cultures were prepared by seeding 1.0 × 10⁶ suspensions of periodontal ligament cells onto five Puropor-200 filters. The following day, root disc pairs were placed on the cell layer, leaving a gap (interdental space) of 0.1–0.3 mm. Five days later, all cultures received equal aliquots of alveolar bone cells. The cultures were terminated and processed for microscopic and morphometric evaluation after 56, 112 and 124 days. All cultures demonstrated a dense fiber-fringe attachment along most of the cementum-lined surfaces of root discs. Adjacent to other root-disc surfaces, cells were surrounded by halos of their collagenous product. Mean diameters of collagen fibrils for the 56-, 112- and the two 124-day cultures were 64.6, 48.9 and 62.6 nm, respectively. Compared to results obtained in this system with periodontal ligament cells alone (Bernstein et al. 1988), the fiber fringe in this experiment was denser, composed of collagen fibrils with a larger diameter, and maintained for longer duration in culture. These findings support the hypothesis that cells from the alveolar bone participate, as a normal component of the periodontal ligament, in the maintenance and repair of periodontal ligament attachment.