____________________________________________________________________Original Research J Dent Specialities.2015;3(2): 140-145 140 Detection of apoptosis in human periodontal ligament during orthodontic tooth movement Ritu Duggal 1 , Neeta Singh 2 ABSTRACT Aim: To compare distribution of apoptotic cells in the Periodontium following Orthodontic force application, to study the apoptotic index and co-relate with different phases of tooth movement. Material and methods: 100 patients, age 12-20 years, of class II div 1 malocclusion, were randomly divided into Groups I to V, requiring first premolars extraction with fixed Mechanotherapy. After leveling, canine was retracted using closed coil spring (100 gm forces). Surgical extraction of premolar was performed on 0, 3,7,14 & 21 days. Periodontium tissue was processed and apoptosis was evaluated by TUNEL assay. Apoptotic cells were counted from 4 different fields per slide and compared with the basal group. Results: The mean Apoptotic Index increased from day 3 and peaked at day 7 for both compression and tension sides. On tension side, at days 14 & 21 apoptosis wasn’t significant indicating earlier recovery. On compression side, there is more gradual decrease in apoptosis with lowest mean values at day 21, though not same as the basal level, indicating that the periodontal tissues require more than 21 days for complete recovery. The overall difference in apoptotic rate was statistically significant for both compression and tension sides. Conclusion: Tissue response is a time-dependant normal physiological process where periodontal cells are cleared by apoptosis. The correlation coefficient value indicates the apoptotic activity increased with force on compression side & increased significantly on tension side too, signaling towards force-dependant direct relation between the two. Cells on tension side showed a more rapid rate of recovery as compared to compression side. Keywords: Periodontium, Orthodontic, Mechanotherapy, Force-dependant INTRODUCTION he Mechanical force during tooth movement was reported to create compressed and cell-free areas, so called hyalinized tissue, in the periodontal membrane (Reitan and Rygh 1994). Hyalinized tissues were described as necrotic (Rygh 1972, 1973) or degenerating (Nakamura, Tanaka and Kuwahara, 1996) tissue from ultra-structural observations. The precise mechanism by which periodontal ligament cells disappear at the compressed area during tooth movement remains unclear. In the present study we examined whether periodontal ligament cells undergo apoptosis at the compressed area during tooth movement by using terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL). Access this article online Quick Response Code: Website: www.its-jds.in DOI: 10.5958/2393-9834.2015.00003.0 OBJECTIVES 1. To study the Apoptotic Index in the periodontal tissue clearance during tooth movement. 2. To compare tissue changes in the Periodontium on the 3 rd , 7 th , 14 th & 21 st day after application of orthodontic force. 3. To correlate the above findings with different phases of orthodontic tooth movement. MATERIAL AND METHODS The study comprised of 100patients, age 12-20 years, having Class II division 1 malocclusion requiring first premolars extraction to be treated with Fixed Mechanotherapy using Standard edgewise Prescription (0.022”×0.028” slot). Leveling and alignment was done using .016”, 018” and .020” stainless steel wires. Sentalloy closed coil springs were attached between canine & first premolars (200 grams force). Ethical clearance was obtained from the Ethics Committee of All India Institute of Medical Sciences, New Delhi with reference number (A-11-6/4/05) dated 8 August 2005. Written consent was obtained from each patient prior to their inclusion in the study. The patients were divided into five groups on the basis of the staging of the premolar extraction with respect to time. (Table 1) 1 Professor, Department of Orthodontics and Dentofacial Deformities, Centre for Dental Education and Research, A.I.I.M.S., New Delhi. 2 Professor, Department of Biochemistry, All India Institute of Medical Sciences, New Delhi Address for Correspondence: Dr. Ritu Duggal Professor Department of Orthodontics and Dentofacial Deformities Centre for Dental Education and Research A.I.I.M.S., New Delhi. Email: ritudug@gmail.com Received: 10/01/2015 Accepted: 15/04/2015 T