Morphological characteristics of the bifurcation area of first mandibular molars

Objectives: The aim of this study was to investigate the frequency of interradicular canals in the bifurcation area of first mandibular molars.

Methods: A total of 117 first mandibular molars were investigated. An access cavity was prepared and the teeth cleaned from pulpal tissue under an ultrasonic bath (5 min) with 5% sodium hypochlorite. The pulp chamber was colored by means of 4% methylene blue and centrifuged (Cryofuge 5000, Heraeus Sepatech/Osterode) at 2000 rpm during five minutes. The teeth were casted in a methyl metacrylate based resin (Technovit 9100, Heraeus Kulzer/Wehrheim) and the area between the pulp chamber floor and bifurcation sliced (MT1 1900, Renfert/Hilzingen) with a 0,145 mm/± 0.03 mm thickness. The frequency of interradicular canals was microscopically observed at a 125 magnification. The results were descriptively analyzed and the confidence interval (in square parenthesis) was calculated with the Clopper-Pearson for binomial distributed variables.

Results: Nine (7.7% [confidence interval: 0.04-0.14]) teeth had an interradicular canal. Two of them (1.7%) showed two interradicular canals. 11 teeth (9.4% [confidence interval: 0.05-0.16]) had 29 interradicular canals, which did not reach either the pulp chamber floor or the bifurcation area.

Conclusion: The results of this study demonstrate that an interradicular canal can appear in first mandibular molars between 4 to 14% (p>0.05).