The Effect of Periodontal Cell Sheet Wrapping and Cell Dipping Co-Culturing Techniques in Delayed Replanted Canine Teeth

Abstract

Background: Prolong delayed tooth replantation results in the necrosis and damage of the root surface periodontal tissue that poses a critical-sized periodontal defect leading to the adverse consequences of ankylosis and replacement resorption with eventual tooth loss. Our study adopted autologous periodontal ligament cell-based therapy as previous studies using physico-chemical methods have not shown to be predictably successful.

Aim: This study aimed to evaluate and compare the effect of periodontal cell-sheet wrapping and cell dipping co-culturing techniques in periodontal regeneration and prevention of ankylosis and replacement root resorption in delayed replanted teeth in dog model.

Methods: Four canine roots each in the negative and the positive control groups were endodontically treated, extracted, replanted immediately and after one-hour bench-dry, respectively. Eighteen experimental roots were extracted for periodontal fibroblasts explant. The latter was subcultured with medium containing 200 µg/ml Ascorbic acid while the roots were surface-denuded, endodontically treated, sterilized and conditioned with 17% EDTA. These treated roots were either dipped in cell suspension of 10x106 PDL fibroblasts (8 roots) or cell sheet wrapped (10 roots). The cell-coated roots were subsequently replanted according to a submerged protocol. After 6-weeks and 12-weeks, the roots and the jaw bone were harvested, step-serially sectioned and histomorphometrically evaluated. Statistical analyses were performed using Kruskal-Wallis and Mann-Whitney U tests.

Results: For the negative control group (N) in which the roots were replanted immediately, there was high occurrence of favorable healing (87.19%) and low occurrence of replacement resorption (2.81%). For the positive control group (P) where the roots were replanted after 60-min bench-dry, there was low occurrence of favorable healing (4.17%) and high occurrence of replacement resorption (83.64%). In comparison, cell sheet wrapping group (CS) had high occurrence of favorable healing at both 6-weeks and 12-weeks (89.50% and 85.63%, respectively) and low occurrence in replacement resorption (9.68% and 14.38%). Similarly, cell dipping co-culturing group (CD) had high occurrence of favorable healing at both timings (90.35% and 88.44%, respectively) and low occurrence in replacement resorption (6.56% and 11.56%). There was significant differences between group CS and group P as well as between group CD and group P in the occurrence of favorable healing and replacement resorption (p=0.002). On the other hand, there was no statistically significant difference between group CS as well as group CD and group N in the occurrence of favorable healing (p=0.839) and replacement resorption (p=0.454). There was no significant difference between the 6-week and 12-week observations for each experimental group. Histologically, the PDL formed appeared to be better organized with increased observation period. Conclusion: The role of cell-based therapy on critical-sized periodontal defect in delayed-replanted canine teeth might be exploited in tooth recycling and/or transplantation.