Assessment of Positional Variation of Maxillary Permanent First Molar with respect to the Infrazygomatic Crest (Key Ridge) in Skeletal Class I, II and III Cases

Introduction: To assess the positional variations of maxillary horizontal and vertical plane with respect to infrazygomatic crest (key ridge) in skeletal class I, II and III cases. Materials and methods: A total of 103 lateral cephalograms comprising of 40 skeletal class I (control group), 35 class II and 28 class III cases were selected and analyzed. Six parameters were chosen to compare the vertical and the horizontal Results: key ridge in class II and III was 2.42° and 6.97° as compared to class I which was 5.35°. The mesiobuccal cusp tip of maxillary respectively as compared to class I (1.62 mm). The mesiobuccal was 2.14 and 2.82 mm as compared to class I (1.27 mm). Conclusion: infrazygomatic crest and was ahead of the key ridge in all the mesially in class II and III cases as compared to the class I cases but, in class III, it was more upright as compared to class I and II.