C-shaped root canal system in mandibular 2nd molars in Korean people evaluated by cone beam computed tomography

PURPOSE: To determine the anatomical characteristic of C-shaped canal systems in Korean mandibular 2nd molars by cone beam computed tomography (CBCT). MATERIALS AND METHODS: The 824 CBCT images were evaluated. These patients were taken CBCT for the diagnosis and treatment of dental implantation on 2013. The 711 mandibular 2nd molars were examined. The configuration of root canal systems were classified according to modified Melton's classifications. RESULTS: Of the 711 mandibular 2nd molars, 21.5% had C-shaped canal systems. This prevalence did not differ with tooth position. Most of the C-shaped canals with bilateral molars were symmetrical. Of the C-shaped canal, the most common configuration Type were Melton's Type I (89%) in the orifice level and Melton's III (83.8%) in the apical level. The prevalence of C-shaped canal was higher in female (25%) than male (13.9%) (P < 0.05). CONCLUSION: A high prevalence of C-shaped canals were observed in Korean mandibular 2nd molars. For successful C-shaped root canal treatment, the comprehension of root canal systems was important.

Influence of first premolar extraction on second and third molar angulation - A clinical study.

ABSTRACT Background: In modern populations, the impaction rate is higher for third molars than for any other tooth. Due to the speculation of third molar role on late incisor crowding, many orthodontists prescribe removal of third molars before, during or just after orthodontic treatment. Objectives: The aim of this study was to compare whether orthodontic extraction of first premolar lead to any angular changes in second and third molars. Material and method: Orthopantograms of 20 patients undergoing orthodontic treatment were collected pre and post treatment. The patients were divided into two groups – nonextraction and extraction group. Each group consisted of 10 patients. The angles were measured between the long axis of 2nd molar and 3rd molar with horizontal plane. Changes in 2nd and 3rd molar angulation from pre-treatment to post treatment for two groups were compared by Mann- Whitney utest. Results: Statistical analysis revealed that maxillary and mandibular 2nd and 3rd molar showed an improvement in angulation but it was statistically non-significant. Conclusion: The findings of the present investigation suggest that premolar extraction therapy has a favourable effect on maxillary second & third molar angulation, while no changes in mandibular second & third molar angulation during treatment were found in patients treated with and without premolar extractions.