Abstract:

Objective

To evaluate the root canal morphology of mandibular premolars and the role of dental operating microscope in clinical treatment of lower premolars with multiple canals.

Methods

152 mandibular premolars were treated endodontically. Two kinds of preoperative radiographs were taken for each tooth， using straight projection and eccentric projection. The root canal morphology was recorded according to Vertucci's classification. Under dental operating microscope， the teeth with multiple root canals were preflared by GG drills，shaped using Ni-Ti rotary instruments ProTaper， cleaned using sodium hypochlorite， and obturated by vertical condensation technique. The number of teeth that were found to have multiple canals was recorded with and without the use of microscope， respectively. The efficiency of preparation and obturation was analyzed with radiographs before， during and after operation.

Results

The mandibular first premolar had one canal in 67.1% and multiple canals in 32.9% of the teeth. The mandibular second premolar had one canal in 92.5% and multiple canals in 7.5%of the teeth. The treatment with the use of microscope revealed more teeth with multiple canals than that without the use of microscope. There were no transportation， apical blockage， ledge，and instrument fracture in all cases. 146 teeth were filled well， 5 showed slight over-filling， and 1 under-filling.

Conclusion

Using dental operating microscope， the mandibular premolars with multiple root canals could be treated well.

Key words: Mandibular premolar, Dental operating microscope, Endodontic treatment