OBJECTIVE: To compare second molar angulation to the occlusal plane with cephalometric measurements corresponding to AP skeletal discrepancy. MATERIALS AND METHODS: 72 patients' pre-orthodontic records were analyzed. A plane was constructed along the cusps of the upper second molar and measured to a proxy for the occlusal plane. The angle between the planes was measured. ANB, Wits appraisal, U1-SN, IMPA, A-B perpendicular to Frankfort, and overjet were measured on the patients' cephalograms. Generalized additive mixed model analysis was performed to analyze the relationship between the second molar angulation and the cephalometric measurements. RESULTS: All six cephalometric measurements showed a significant relationship with the second molar angulation, with Class III patients having a larger angle than Class II and I patients. CONCLUSIONS: Class III patients have upper second molars that are significantly tipped from the occlusal plane. The second molars require special attention for correction prior to orthognathic surgery for Class III patients in order to avoid deleterious effects from the malpositioned teeth.
OBJECTIVE: To compare second molar angulation to the occlusal plane with cephalometric measurements corresponding to AP skeletal discrepancy. MATERIALS AND METHODS: 72 patients' pre-orthodontic records were analyzed. A plane was constructed along the cusps of the upper second molar and measured to a proxy for the occlusal plane. The angle between the planes was measured. ANB, Wits appraisal, U1-SN, IMPA, A-B perpendicular to Frankfort, and overjet were measured on the patients' cephalograms. Generalized additive mixed model analysis was performed to analyze the relationship between the second molar angulation and the cephalometric measurements. RESULTS: All six cephalometric measurements showed a significant relationship with the second molar angulation, with Class III patients having a larger angle than Class II and I patients. CONCLUSIONS: Class III patients have upper second molars that are significantly tipped from the occlusal plane. The second molars require special attention for correction prior to orthognathic surgery for Class III patients in order to avoid deleterious effects from the malpositioned teeth.
Authors: Beth A Troy; Shiva Shanker; Henry W Fields; Katherine Vig; William Johnston Journal: Am J Orthod Dentofacial Orthop Date: 2009-02 Impact factor: 2.650