Furcation Anatomy Revisited: A Two Dimensional Radiographic Evaluation of Healthy Mandibular Molars

Introduction: Furcation regions present some of the most significant challenges to the successful outcome of periodontal therapy. Due to their anatomical complexities, the areas become inaccessible, and instrumentation is generally tricky and often incomplete. Hence, it is essential to have a thorough knowledge of molar anatomy to assess the case difficulty, appropriate diagnosis, and treatment planning.

Aim: To radiographically evaluate and classify the furcation anatomy of mandibular first and second molars based on root trunk length and root divergence angle.

Materials and Methods: This retrospective observational study was carried out in AB Shetty Memorial Institute of Dental sciences, Mangalore between February and March 2020. Orthopantomograms (OPG) with permanent healthy first (25 right and 25 left) and second mandibular molars (25 right and 25 left) with no alveolar bone loss obtained from systemically healthy individuals were selected for the study. They were screened for root divergence angle and root length to root trunk length ratio. According to the root divergence angle, the total sample was classified as Group I (with angle <30°), Group II (with angle 30°to 60°), Group III (with angle >60°). They were classified into Type A, B, and C based on Hou and Tsai classification. Type A root trunks involving the cervical third or less, Type B involves upto cervical half of the length of the root and Type C involves cervical two-thirds of the root, respectively. The data were collected and entered in the Microsoft Excel sheet. Mean and standard deviation was calculated for root divergence. Statistical analysis was performed using Statistical Package for Social Sciences (SPSS) version 23.0. Student t-test was used to compare intragroup variations in root divergence in the left and right molars. The p<0.05 was considered to be significant.

Results: Total 100 teeth (50 mandibular first molar (25 left and 25 right) and 50 mandibular second molars (25 left and 25 right)) were included in the study and analysed. In terms of Furcation Angle (FA), mandibular left first molar showed an increased frequency of Group II (48%) and Group III (48%), while mandibular left second molar showed an increased frequency of Group II (68%). Among mandibular right first molar Group III (56%) showed an increased frequency, while Group II (92%) was commonly seen in right second molar. Intergroup comparison revealed a statistically significant difference in divergence between mandibular left first and second molars (36 and 37) p<0.01, mandibular right first and second molars (46 and 47) (p<0.01). Divergence of furcation was more significant in 36 and 46 than 37 and 47, respectively. The current study results showed a higher frequency of Type A in all the four involved teeth, i.e., left first (96%) and second (68%) molars, right first (92%) and second (88%) molars.

Conclusion: The study results showed an increased frequency of Group II FA and Type A root trunks. The divergence of furcation was greater in first molars compared to the second molars.