Evaluation of Mesiodistal Inclination of Permanent Maxillary and Mandibular First Molar in Different Angle’s Molar Relation - A Cephalometric Study

Abstract

Context: Angle's molar relationship is the most widely used classification in spite of introduction of various other classifications. At the end of the treatment, the molars are finished in a Class I, II, or III molar relation. Achieving a proper cusp to fossa relation is necessary for attaining a balanced occlusion. Thus, it is important to know the ideal inclinations of the upper and lower first molars, thereby assisting in achieving stable relationship. Aims and Objectives: This study aims to evaluate mesiodistal inclination of permanent maxillary and mandibular first molars in Angle's Class I, II, and III molar relationships in relation to the occlusal plane. Materials and Methods: Lateral cephalograms of 16-30 years old individuals with Class I, II, and III molar relations were selected from the archives of the department of orthodontics. They were traced in Dolphin Imaging software, and the angle between the first molar and occlusal plane was calculated. Results: There was a statistically significant difference in the inclination of maxillary first molar in between Class I and Class III. No significant difference was noted in the inclination of maxillary first molar in case of Class I and Class II. In case of mandibular molars, there was statistically significant difference in case of Class I and Class II and between Class I and Class III. Conclusion: When the end molar relationship of a case is planned to be Class I, the upper molar should be at an angle of 84.12° to the occlusal plane. When the end molar relationship of a case is planned to be Class II, the upper molar should be 84.15° to the occlusal plane. When the end molar relationship of a case is planned to be Class III, the upper molar should be inclined at an angle of 87.07° to the occlusal plane. This helps in achieving an ideal cusp to fossa relationship, thereby stabilizing the occlusion.