Comparative cone-beam computed tomographic evaluation of maxillary incisor intrusion and associated root resorption: Intrusion arch vs mini-implants.

INTRODUCTION: Various literature has verified that apical root resorption is a common adverse effect of orthodontic treatment, particularly intrusion. Conventional radiographic techniques underestimated root lengths and overestimated tooth lengths. Cone-beam computed tomography (CBCT) is a useful diagnostic tool to detect orthodontically induced external apical root resorption. This prospective study aimed to compare maxillary incisor intrusion and associated root resorption via CBCT. METHODS: Thirty patients aged 16-23 years, having a deepbite of 6-8 mm and excessive gingival display on smiling, were divided into 2 groups: group 1, with 15 patients who were treated with Burstone intrusion arch, and group 2 with 15 patients who were treated with mini-implants applying 100 g of intrusive force for 4 months with activation done every 4 weeks. During this 4-month study period, no treatment was performed other than the intrusion of incisors. CBCT scans were obtained before and after the intrusion phase of treatment to compare the amount of intrusion and associated root resorption among both groups. RESULTS: No significant difference was found in mean incisor intrusion between groups 1 and 2 (P = 0.772), with slightly more proclination of incisors in group 1, resulting in a significant (P = 0.018) increase in the vertical change of incisal edge in group 1. A statistically significant difference was found in root resorption among both groups (P = 0.004), with more root resorption in group 2. CONCLUSIONS: The results of this study indicate intrusion with both the intrusion systems using appropriate intrusive forces is effective in opening the bite with slightly more external apical root resorption in the mini-implant group.

Evaluation of the Nature of Collagen Fibers in KCOT, Dentigerous Cyst and Ameloblastoma using Picrosirius Red Stain - A Comparative Study.

BACKGROUND: Reciprocal interaction between dental epithelium and mesenchyme is thought to be crucial for normal odontogenesis. Thus, the mesenchymal influence of the fibrous capsules may play an important role in the maintenance of epithelial expression. Collagen is the major component of the extracellular matrix and possibly there is an alteration in the nature and structure of collagen in various pathological conditions. Studies by polarizing microscopy have also shown that there is a difference in collagen and probably these differences may play a role in their biologic behaviour. AIM: The purpose of this study was to evaluate the nature of collagen fibers in keratocystic odontogenic tumour (KCOT), dentigerous cyst (DC), unicystic ameloblastoma (UA) and solid/multicystic ameloblastoma (SMA) and correlating this with their biological behaviour. MATERIALS AND METHODS: Five diagnosed cases each of UA, SMA, KCOT and DC were taken and stained using Picrosirius red stain kit and evaluated using a polarizing microscope. STATISTICAL ANALYSIS: Chi-square test was used to analyse the results. RESULTS AND CONCLUSION: Collagen fibers in dentigerous cysts showed predominant yellowish-red birefringence and fibers in KCOT and ameloblastomas showed a predominantly greenish-yellow birefringence. Hence, our study suggests that the nature and character of collagen fibers may influence the clinical behaviour of the lesion. Since ours is a pilot study, to corroborate our view, studies with larger sample size are required to substantiate the results.