OPG Based Study to Analyze Essential Parameters of Impacted Lower Third Molar among North Malaysian Population: A Retrospective Study

Background: The third molar in permanent dentition is the last tooth to be erupted, the lack of space causes uneruption. Purpose: To determine the difference in various variables between erupted and impacted lower third molar group. Methods: Quasy experimental study done at the AIMST Dental Institute, comprised 200 patients OPG’s were divided into two groups; Group A - erupted, while Group B - impacted mandibular third molars. Results: The third molar angulation in group A was 84.32 ± 11.59 and group B 64.15 ± 30.92 with P value 0.000. The Mesioangular slope of the third molar in group A was 7.14± 9.64 and group B 29.54 ± 35.77 with P value 0.000. The second molar angulation in group A was 88.32 ± 7.59 and group B 86.58± 15.06 with P value 0.302. Gonial angle in group A was 123.02 ± 7.60 and group B 120.08 ± 8.3 with P value 0.010. The third molar mesio-distal crown width in group A was 14.15 ± 1.28 and group B 14.47 ± 1.17 with P value 0.067. Retromolar space in group A was 19.09 ± 2.97 and group B 13.54± 2.96 with P value 0.000. The anterior-posterior distance of the arch of the erupted third molar in group A was 58.88 ±6.23 and group B 62.31 ± 5.75 with P value 0.007. Conclusion: The impaction of third molar is greatly associated with angulation of third molar, mesioangular slope of the third molar and retromolar space.