A novel method for measuring tooth angulation in permanent mandibular second molars with delayed tooth eruption.

OBJECTIVE: To investigate the effect of angulation of permanent mandibular second molars (MM2) on eruption problems and investigate a new method of measuring MM2 angulation for the diagnosis and evaluation of delayed tooth eruption (DTE) for easy use in dental practice. DESIGN: Retrospective study. SETTING: Department of Orthodontics, Necmettin Erbakan University. PARTICIPANTS: A total of 98 patients aged 9-18 years. METHODS: Patients with 64 permanent MM2s with delayed eruption problems were included in the study group. The control group consisted of patients with 83 normally erupted teeth. In addition, a sub-group, consisting of 23 patients showing unilaterally delayed eruption of the same teeth, was set as a split-mouth group. All patients with unilateral delayed eruption of second molar teeth were selected from the study group to form the sub-group. Angulations of permanent MM2s were measured on panoramic radiographs with two measurement methods: (1) a new method; and (2) a previously accepted method. The comparison of the study and control groups was performed by Mann-Whitney U-test and the split-mouth group was analysed with the paired t-test. The P value was set at 0.05 for statistical significance. RESULTS: Measurements of the tooth angulation values of the study group were significantly higher than in the control group for both measurement methods (P < 0.001). In addition, in the split-mouth group, angulation values of delayed eruption side were significantly higher than the erupted side (P < 0.001). CONCLUSION: Increased angulations of permanent MM2s could be associated with delayed eruption problems of these teeth. This new method could be useful in clinical dentistry to determine the eruption evaluation of lower second molars.