Root and canal morphology of Indian maxillary premolars by a modified root canal staining technique

The aim of this study was to investigate the root and canal morphology of maxillary first and second premolars in Indians by a modified canal staining and tooth clearing technique. Maxillary first (350) and second (350) premolars were collected, and the morphology and number of roots analyzed. After cleaning, the teeth were immersed in India ink and placed in a hyperbaric oxygen chamber at 0.6 MPa for 2 h. The teeth were then demineralized and cleared. Digital images of the teeth were examined under magnification to evaluate the number of root canals, root canal system configurations, number of apical foramina, and intercanal communications. Root canal configurations were identified based on Vertucci's classification and Gulabivala's additional classes. The most common root morphology of the first premolars was the classical two separate root morphology (a Caucasian trait) and that of the second premolars was a single-root morphology (a Mongoloid trait), though other morphologies such as singlerooted first premolars and three-rooted first and second premolars were also identified. A "radiculous" first premolar was identified in two samples. The buccal roots of the first premolar showed the maximum variation, the most common being type I (Vertucci's classification), followed by type IV. The highest incidence of intercanal communications was found in the single-rooted first premolars. All roots exhibiting type IV and V canal configurations showed two separate apical foramina, while additional type 2-3 canal configurations showed three separate apical foramina. The root number and morphology as well as the canal morphology of Indian maxillary premolars showed both Mongolian and Caucasian traits.