No abstract

Clinicians should be aware of this unusual root morphology in mandibular first molars in Caucasian people. Radiographs exposed at two different horizontal angles are needed to identify this additional root. The access cavity must be modified in a distolingual direction in order to visualize and treat the RE, this results in a trapezoidal access cavity.

Under the conditions of this study, ProTaper instruments performed acceptable tapered preparations in all canal types. When using F2 and F3 in curved canals, care should be taken to avoid excessive removal at the inner curve, leading to danger zones. In addition, care should also be taken to avoid deformation of the F3 instrument.

Under the conditions of this study, GT Rotary Files produced acceptable canal shapes. In narrow and curved canals, the length of the straight section of the canal determines the direction of transportation more than the angle of the curve. In the 60 degrees curves, a high incidence of instrument deformation was found when using the 0.04 tapered instruments.