Radiographic evaluation of aetiology of mandibular third molar impactions

ABSTRACT

To determine the role of various factors in the etiology of lower third molar impaction by using measurements on conventional panoramic radiograph. Orthopantomograms of 100 patients having full dentition with bilateral mandibular third molars were included in the study ranging between ages of 18-39 years. All the patients were divided into erupted and impacted groups on the basis of status of lower thirdmolar on Orthopantomogram. All Radiographs were traced on overlying acetate paper and analyzed by measuring retromolar eruption space [from Xi-7 and AER-7] mesiodistal width of lower third molar, space width ratio and angulations of lower third molar, In erupted group, retromolar eruption space measured from Xi-7 was 31.79 +/- 3.38 where as in the impacted group, it was 26.93 +/- 4.11. Retromolar space measured from AER-7 was I 6.09 +/- 2.35 mm among erupted group whereas for impacted group, it was 11.06 +/- 3.64 mm. Mesiodistal width of mandibular third molar among erupted group was 13.29 +/- 1.41 mm while among impacted group, it was 13.70 +/- 1.72 mm. Space width ratio among impacted group was 0.83 +/- 0.36 whereas among erupted group, it was 1.22 +/- 0.20. Mean angulations of lower third molars was 7.79° +/- 9.15 among erupted group, where as among impacted group, mean angulations of lower third molars was 34.68° +/- 27.68. Both the groups were statistically different in all the tested variables except mesiodistal width of lower third molar