Morphology and Clinical Observation of the Mandibular Third Molar.

Objective: The aim of this study is to investigate the morphology and the location of canal orifices of the mandibular third molars.Methods: 159 extracted mandibular third molars were collected.The number of cusps and roots was directly observed.The number and length of root canal orifices was detected by microscopy.The teeth were radiographed in buccolingual and mesiodistal directions.Results: 54.09 % of 159 mandibular third molars had fused or conical roots,40.51% had two separate roots.Most teeth had two canals(55.35%).Of 340 canals,14 were S-shaped canals,and 36(22.80%) were C-shaped canals,in which 18 teeth(50.0%) were type Ⅰ,13(36.1%) were type Ⅱ,and 5((13.9%)) were type Ⅲ.Conclusion: There was a great anatomical variability of the mandibular third molars,including C-shaped,S-shaped and curvature canals.