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[The preliminary analysis on the changes of the oral functional space in Class II division 1 malocclusion after
Objective:
The purpose of this paper is to study the area changes of the oral functional space in the patients with Angle's Class II division 1 malocclusion after triggered by FR-I functional appliances.
Methods:
Twenty patients with Angle's Class II division 1 malocclusion were selected, and the patients were selected by the standards of an horizontal growth pattern with normal maxilla, retracted mandible and short lower facial height. All patients were triggered by FR-I functional appliances and achieved the Angle's Class I occlusion after treatments. The average periods of the treatments were about 9 months. The assessments were made from the lateral cephalograms taken in centric occlusion before and after treatments. The upper and behind borders of the oral functional space are hard palate and soft palate, the forward border is the lingual side of upper and lower incisors, the lower border is the line between apex of lower incisor and lower first molar. The graphics from the lateral cephalogram were painted and input into the computer by scaner, which were measured by special software. Self-controls of individuals before and after treatments were used in statistic analysis.
Results:
The paired-samples t test confirmed the oral functional space was enlarged after triggered by FR-I functional appliance, which was induced by obviously increased mandibular body and ramus, anterior lower facial height and posterior facial height. At the same time, the angle of Y axis increased and the upper incisor inclined lingually, but the inclining angle of lower incisor was not obvious.
Conclusion:
Enlarged oral functional space facilitates the development of the maxilla, mandible and alveolar bones and consummates the functions of oral and jaw system. This study aids the design and application of FR-I functional appliance.