Take Home Pearl:
An association exists between static occlusion and dynamic occlusion in untreated subjects. Background:
During orthodontic finishing, orthodontists typically assess 2 aspects of a patient’s occlusion- static occlusion and dynamic occlusion. A goal for orthodontists is to achieve a Class I molar and canine relationship in static occlusion. It is typical that orthodontists are taught to achieve canine guidance in protrusive position. But, is there any association between static occlusion and dynamic occlusion? Objective:
To determine which type of dynamic occlusion is associated with which type of static occlusion. Design/Participants:
Descriptive analysis of 94 dental students between the ages of 21 and 30 years. Methods:
None of the subjects had received previous orthodontics treatment, and all subjects had a fully permanent dentition. Each of these subjects was classified initially with respect to their static occlusion (Class I, Class II, or Class III). Then, the subjects were asked to move their mandible 0.5 mm right and left to determine which teeth contacted. Then they moved 3 mm right and left to determine which teeth were in contact. Finally, they were asked to move their mandible anteriorly in order to determine which teeth contacted in protrusive position. Results:
The resuts of this study showed that, in static occlusion, 49 subjects had a Class I relationship, 27 subjects had a Class II relationship, and 18 subjects had a Class III occlusion. When the authors evaluated the dynamic occlusion approximately 24% had bilateral group function at 0.5 mm lateral guidance, and 18% had mixed canine guidance and group function. However, at the 3 mm position, the guidance pattern changed predominately to canine guidance. Fifty percent of subjects at that position had bilateral canine guidance. The authors compared the static and dynamic occlusion, and they found an association between Class I and bilateral canine protected occlusion at the 0.5 mm lateral excursion. However, at the 3 mm lateral guidance, only 50% of the Class I and 11% of the Class III subjects had bilateral canine protected occlusion. On the other hand, 70% of the subjects with Class II relationships had bilateral canine protected occlusion at 3 mm. Conclusions:
The authors conclude that there is an association between static occlusion and dynamic occlusion, and that at the 3 mm lateral excursion; bilateral canine protected occlusion was only predominant in subjects with a Class II relationship. Reviewer’s Comments:
subjects finish with a slight Class II molar and canine position, they do have better canine guidance in lateral occlusion.
This was an interesting comparison. Although we as orthodontists typically try to achieve a Class I relationship for our patients, often, if Reviewer:
Vincent G. Kokich, Sr, DDS, MSD
