The Affection Of Shortened Dental Arch Method To Masticatory System

Objective:To investigate the possible effect that shortened dental arches (SDAs) may cause to the periodontium and temporomandibular joints, and to provide instruction for clinical application.Methods:Bite force, masticatory muscle electromyogram and masticatory efficiency were recorded in five dentate subjects who clenched maximally on intra-oral appliances, creating symmetrical SDAs experimentally. A finite element jaw model was created by the CT and MRI data of the head of a volunteer, periodontium stress and joint loads were calculated on this model.Results:1. There is no significant difference in bite force and EMG when dental arch is shortened.2. Masticatory efficiency decreased slightly when the second molar missed, and went on decreasing with dental arch.3. The force on articular disc arises when dental arch is shortened, but there is no significant movement of the utmost pressure-point.4. The periodontium stress of each tooth increased with shortened dental arch occlusions.Conclusion:1. The shortened dental arch will not affect bite force significantly, but masticatory efficiency will decrease.2. The stress on articular disc stress will arise when dental arch is shortened, which may cause temporomandibular disorders.3,The stress on each tooth begin to exceed the periodontal potential when the first molar missed, which may cause periodontal diseases.