Different Ways To Remove Necrotic Periodontal Ligament On Delayed Tooth Replantation: Scanning Electron Microscopy And Histomorphometric Analysis

Objective: One of the important factors attributing to successfuldelayed replantation of avulsed teeth is assumably the removal of necroticperiodontal ligament remnants, which may prevent the occurrence of externalroot resorption. There are lots of ways to this, but the best one has not beendecided yet. So the purpose of this study was to seek the most effectivetechnique for removal of root-adhered periodontal ligament.Materials and methods: Thirty-five roots of healthy right mandibularfirst premolars extracted for orthodontic purposes were selected. Afterextraction, the teeth were kept dry at room temperature for at least1h, andthen divided into five groups, as follows: Group1(control)—the root-adheredperiodontal ligament was preserved; Group2—periodontal ligament remnantswere removed by scraping root surface with a scalpel blade;Group3—removal of the periodontal ligament by immersing the root in the 1%sodium hypochlorite solution for5minutes; Group4—removal of theperiodontal ligament by immersing the root in the2%sodium hypochloritesolution for5minutes; Group5—removal of the periodontal ligament byimmersing the root in the1%sodium hypochlorite solution for10minutes.For each group, two of the specimens were examined by scanning electronmicroscopy and the other five were processed and paraffin-embedded, afterwhich serial transversally sections were obtained from the middle, apicalthird of the root and stained with hematoxylin and eosin forhistomorphometric analysis. Both periodontal ligament remnants andpreservation or removal of the cementum layer concomitantly with theseprocedures was assessed. Data were analyzed statistically using one-wayANOVA and Tukey’s Test.Results: In reference to periodontal ligament remnants, Group1showed62.33%region covered with periodontal ligament, presenting the largestareas(P＜0.05). Group2showed22.42%, being smaller than Group1(P＜0.05), but much larger than Group3, Group4and Group5(P＜0.05); The lastthree groups showed0.885%,0.386%and0.237%respectively, with nostatistically significant differences among them. As for preserved cementumlayer, Group2lost7.90%area of cementum, which showed the worst result(P＜0.05); While Group1, Group3, Group4and Group5lost0.031%,0.084%, 0.065%and0.057%respectively, with no statistically significant differencesamong them.Conclusion: The quantitative and qualitative analyses of the resultsshowed that scraping root surface with a scalpel blade technique could notwipe off the root-adhered periodontal ligament. To make matters worse, itmight do damage to cementum layer, which could not be a best way. Sodiumhypochlorite solution could both clean up the periodontal ligament remnantsand preserve cementum layer, which might be an ideal choice. But furtherinvestigations are in progress to determine the best immersed time andconcentration of the solution.