Incidence of third root in mandibular permanent first molar: An endodontic challenge

Abstract

Aim: To investigate the incidence and the morphology of third root for the mandibular permanent firstmolars from indigenous Iraqi population and their significance in the successful of endodontictreatment. Materials and Methods: A clinical, radiographical prospective evaluation of firstmandibular permanent molar teeth (n= 788) and laboratory analysis of 695 extracted first mandibularpermanent molars collected from University Mosul, College of Dentistry, Department of ConservativeDentistry and private dental clinic were collected and examined. All the clinical cases treated as thirdroot present, unless otherwise both 90º, 20° mesial radiographical shift and trapezoidal access openingexcluded the presence of this macrostructure. The third root was classified in three groups on the basisof the curve of the root/root canal according to Ribeiro and Consolaro (1997). Chi–square was used todetermine the significance between both genders, whereas descriptive statistics was used to describethe result of observations. Results: Upon clinical and laboratory observation of total 1483 firstmandibular permanent molars, 121 (8.1%) exhibited radix entomolaris (RE), 17 (14%) were classifiedas type I (straight root/root canal), 33 (27.2%) as type II (an initially curved entrance and thecontinuation as a straight root/root canals) and 71(58.6%) as type III (an initial curve in the coronalthird of the root canal and a second buccally orientated curve starting from the middle to apical third). Statistical analysis with Chi–square indicated no significant differences between both genders regarding the occurrence of RE. In all cases, RE occurred bilaterally. Out of 71 teeth attended for clinic, 87.3% teeth required retreatment, while the apparent reason of extraction for 86% of 50 collected extracted teeth with RE seemed failure of endodontic treatment and the cleaning andobturation confined to the mesial and distal canals only. In all cases, the orifice of the RE was locateddistolingual from the main canal in the distal root. Conclusion: Clinicians should be aware of this unusual root morphology in mandibular first molars. 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.