[Different ways to remove necrotic periodontal ligament on delayed tooth replantation: scanning electron microscopy and histomorphometric analysis].
OBJECTIVE
To seek the most effective technique for removal of root-adhered periodontal ligament.


METHODS
Thirty-five roots of healthy right mandibular first premolars extracted for orthodontic purposes were selected. After extraction, the teeth were kept dry at room temperature for at least 1 h, and then divided into five groups as follows: Group 1(control)-the root-adhered periodontal ligament was preserved; Group 2 (mechanical removal)-periodontal ligament remnants were removed by scraping root surface with a scalpel blade; Group 3 (chemical removal 1)-removal of the periodontal ligament by immersing the root in 1% sodium hypochlorite solution for 5 minutes; Group 4 (chemical removal 2)-removal of the periodontal ligament by immersing the root in 2% sodium hypochlorite solution for 5 minutes; Group 5 (chemical removal 3)-removal of the periodontal ligament by immersing the root in 1% sodium hypochlorite solution for 10 minutes. The specimens were analyzed histomorphometrically and examined under scanning electron microscopy. Both periodontal ligament remnants and preservation or removal of the cementum layer concomitantly with these procedures were assessed. The data were analyzed using one-way ANOVA and Tukey's test with SAS 8.02 software package.


RESULTS
In regard to periodontal ligament remnants, group 1 presented the largest areas(P<0.05), group 2 showed smaller area than group 1 (P<0.05), but much larger than group 3-5 (P<0.05); The three chemical removal groups had no significant difference. As for preserved cementum layer, group 2 lost most areas, which showed the worst result(P<0.05). The other 4 groups had no significant difference.


CONCLUSIONS
Scraping root surface with a scalpel blade could not wipe off the root-adhered periodontal ligament, and might damage the cementum layer. Sodium hypochlorite solution could clean up the periodontal ligament remnants and preserve cementum layer, which might be an ideal choice.
Department of Pediatric Dentistry, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine; Shanghai Key Laboratory of Stomatology. Shanghai 200011, China. E-mail:falls_chen@189.cn.
Hui
H
Chen
Yang
Y
Zhang
Jun
J
Wang
D003739:Dental Cementum; D006801:Humans; D008855:Microscopy, Electron, Scanning; D010513:Periodontal Ligament / Q000601:surgery*; D012973:Sodium Hypochlorite; D014070:Tooth; D014090:Tooth Replantation / Q000379:methods*; D014092:Tooth Root
D012973:Sodium Hypochlorite