The prevalence of three-rooted mandibular permanent first molars in a German population.

The purpose of this retrospective study was to assess the prevalence of three-rooted mandibular first molars among a German dental school patient population. A total of 800 patients' full-mouth periapical radiographs were screened, and, out of these, 524 patients possessing at least one mandibular first molar were selected. The radiographs of these cases were evaluated under optimal conditions using double magnifying glasses. The incidence of three-rooted mandibular first molars and the correlation between left- and right-side occurrences and between males and females were recorded and analyzed using the chi-square test. A total of 1,024 mandibular first molars were evaluated. Left molars comprised 500 teeth and right molars 524 teeth. Seven patients were found to have a three-rooted mandibular first molar, three females and four males (p = 0.981). The overall incidence of patients with three-rooted mandibular first molars was 1.35%. All three-rooted molars occurred unilaterally. The prevalence of teeth showing an extra root from all teeth examined was 0.68%. The right first molar had an incidence of 0.57% and the left molar of 0.80%, respectively (p = 0.953). In conclusion, the occurrence of three-rooted mandibular first molars among this German population was rare.