RESUMEN
To assess the dimension and types of root trunk of mandibular and maxillary first molars and their influence on the diagnosis and management of molars with furcation involvement. A total of 105 extracted first molars were used in this study. Included teeth comprised 41 maxillary first molars, and 64 mandibular first molars. For each tooth, the vertical dimensions of the root trunk and root length were assessed with a micrometer caliber. The types of root trunk were classified according to the ratio of root trunk height to root length into types A, B and C. Types A, B and C are defined as root trunks involving the cervical third or less, up to half of the length of the root, greater than the apical half of the root respectively. The length of root trunk and the prevalence of different types of root trunk in maxillary and mandibular molars were analyzed. The percentage of root trunk to root length was also calculated. Root trunk types A, B and C accounted for 34.9%, 61.8%, and 3.3% of maxillary molars; 62.5%, 37.5%, and 0% of mandibular molars respectively. In maxillary molars, the prevalence of type-A was found to be 39.1% and 41.4% on the buccal and distal root trunks respectively, while less than that on the mesial root trunk [24.4%]; the greatest prevalence of type B was found on mesial root trunk [75.6%] while type C was found only on the distal root trunk [9.8%]. In mandibular molars, the type-A was found on buccal root trunk and lingual root trunk with a higher prevalence [73.4%, and 51.6%] than type B [26.6% and 48.4%] while no root trunk type C was found in lower molars. The mean root trunk dimension for maxillary molars was 4.9, 4.31, and 3.9mm for the mesial, distal and buccal respectively, while for mandibular molars 3.7mm for the buccal and 4.3mm for the lingual. It was also noted that as the mean root trunk increased, the mean root length decreased. Awareness of root trunk type and dimension may help the practitioner in the diagnosis, treatment plan, and prognosis of periodontally involved molars