Abstract
Background: Dental avulsion is one of the most common and challenging injuries in 7-to-9-year-old children. The research aimed to periodontal ligament (PDL) regeneration using the guided tissue regeneration (GTR) technique utilizing amniotic membrane scaffold, PDL stem cells (PDLSCs), and injectable platelet-rich fibrin (i-PRF) following delayed replantation of immature avulsed teeth in dogs.
Methods: Thirty extracted immature dog teeth underwent a dry environment for 70 minutes (Except for negative control group:10 min) and then, were randomly divided into five groups: 1) Negative control, 2) Positive control, 3) i-PRF: replantation alongside i-PRF, 4) PDLSCs+i-PRF: replantation alongside i-PRF and the suspension of human PDLSCs (xenograft), 5) GTR: replantation alongside amniotic membrane as a barrier on which human PDLSCs were seeded and contained i-PRF. The teeth were assessed clinically and radiographically at one-month and two-month follow-ups. Two months after replantation, the apical and middle third of the teeth roots were examined histologically (qualitative evaluation) and histomorphometrically (quantitative evaluation: percentage of favorable and unfavorable healing). The results were analyzed using the statistical tests of Chi-square, Kruskal-Wallis and Mann-Whitney (significance at p<0.05).
Results: Clinical observations included infraocclusion of a tooth in the positive control group, mobility in the two teeth of the PDLSCs+i-PRF group, and general tooth discoloration. At two months, the positive control group had significantly more pathological resorption radiographically (P<0.05). Histologically, the GTR group had a significantly higher favorable healing rate compared to all except the negative control group (P<0.05). PDLSCs+i-PRF and i-PRF groups also had improved healing over the positive control group (P=0.004), but less than the GTR and negative control groups (both P = 0.04 compared to the GTR group, and P = 0.002 and P=004 compared to the positive control group, respectively). The latter two treatments did not differ statistically from each other (P=0.63). The positive control group demonstrated significantly more pathological resorption compared to other groups (P<0.05), while the negative control showed almost no pathological resorption.
Conclusions: For delayed replantation of avulsed immature teeth, GTR technique using amniotic membrane scaffold plus i-PRF/PDLSCs significantly increased PDL regeneration and decreased unfavorable healing.