Determination of the Real Distance of Mandibular Third Molar to Inferior Alveolar Canal


Aims: To determine the real not radio graphical proximity of mandibular third molar tooth to the inferior dental canal (IDC) using panoramic radiograph. Materials and Methods: 144 mandibular third molars were evaluated by panoramic radiography. The teeth were grouped into erupted vs. un erupted further subdivided by tooth angulations. The real distance from the most inferior aspect of the mandibular third molar tooth to the superior border of the inferior alveolar canal (IAC) was calculated regarding to the reference object used. Descriptive statistics were performed as well as a t test was performed to compare erupted and unerupted teeth, and ANOVA was used to determine a significant difference where exists based upon tooth angulations. In addition, intra observer analysis was done to ensure the standardization of the radiologist interpretation. Results: The mean distance from erupted mandibular third molar teeth to the inferior alveolar canal was 0.23mm. This distance was significantly different from unerupted teeth (P = .000). The mean values for unerupted teeth were negative values which indicated that the apices of all teeth measured was below the superior border of the canal –1.26 mm and as follows: Mesioangular–1.32 mm, vertical – 1.34 mm and –1.04mm for horizontal impactions. Statistically there was no significant positional difference between the impaction groups (P = .835). In general there was a significant difference in third molar position between those age equal and less than 22 years old and those equal and over 23 years old. Conclusions: Unerupted mandibular third molar teeth (mostly vertical impaction) are closer to the inferior alveolar canal than erupted teeth and persons in general of an age equal or less than 23 years old have a closer lower third molar to mandibular canal than other ages and there is no significant relation between this age group and any of impaction types.