IADR Abstract Archives
Compensation Trends of First Molars' Angulation in Different Growth Patterns
Objectives: We investigated the compensatory trends of mesiodistal angulation of the first molars in 1,403 malocclusion cases to compare the differences in angulation of the first molars among cross-sections in different developmental stages, malocclusion classifications and skeletal patterns.
Methods: The medical records and lateral cephalograms of 1,403 malocclusion cases taken before treatment were measured to evaluate compensation of molar angulation in relation to the skeletal jaw. Cases were stratified by age, angle classification, and skeletal patterns. Differences in mesiodistal angulation of the first molars were compared among the stratifications.
Results: We observed three main phenomena. First, the angulation of the upper first molar varied significantly with age, and tipped most distally in cases aged <12 years and least distally in cases aged >16 years. The lower first molar did not show these differences. Second, in Angle Class II or skeletal class II cases, the upper first molar was the most distally tipped, the lower first molar was the most mesially tipped, and opposite angulation compensation was observed in Class III cases. Third, in high-angle cases, the upper and lower first molars were the most distally tipped, and opposite angulation compensation was observed in low-angle cases.
Conclusions: These data suggest that the angulation of molars had compensations for various growth patterns and malocclusion types and awareness of molar angulation compensation would help to adjust occlusal relationship, control anchorage, and increase the chances of long-term stability.
Methods: The medical records and lateral cephalograms of 1,403 malocclusion cases taken before treatment were measured to evaluate compensation of molar angulation in relation to the skeletal jaw. Cases were stratified by age, angle classification, and skeletal patterns. Differences in mesiodistal angulation of the first molars were compared among the stratifications.
Results: We observed three main phenomena. First, the angulation of the upper first molar varied significantly with age, and tipped most distally in cases aged <12 years and least distally in cases aged >16 years. The lower first molar did not show these differences. Second, in Angle Class II or skeletal class II cases, the upper first molar was the most distally tipped, the lower first molar was the most mesially tipped, and opposite angulation compensation was observed in Class III cases. Third, in high-angle cases, the upper and lower first molars were the most distally tipped, and opposite angulation compensation was observed in low-angle cases.
Conclusions: These data suggest that the angulation of molars had compensations for various growth patterns and malocclusion types and awareness of molar angulation compensation would help to adjust occlusal relationship, control anchorage, and increase the chances of long-term stability.
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