LAUSR

The objective of this study was to investigate the complex anatomy of mesiobuccal roots, supporting and complementing commonly applied clearing technique, using access cavity modification and the pulpal groove deepening method. Three hundred and ninety eight extracted intact human maxillary first molars were included in this study. Firstly, modified rhomboida l shape access cavities were prepared then, the developmental groove between the mesiobuccal and the palatal canals was deepened 1 mm w ith a round slow speed bur. Indian ink was injected into both the canal orifices of mesiobuccal roots and into the groove between m esiobuccal and palatal canals, using a 22 gauge syringe. Then the clearing technique was applied. The incidence of one canal was 30.90 %, two canals was 62.07 %, three canals was 7.03 %. In twenty five (6.28 %) of the mesiobuccal roots, 8 root canal types, which are no t in luded in Vertucci’s classification, were seen. All these root canal types had three root canals. The establishment of adequate access and deep ning of the pulp chamber floor increased the probability of locating the third canal in the mesiobuccal root of maxillary first mola rs.