ABSTRACT

Objective:

The aim of this study was to record the electrical activity of masticatory muscle fibers (electromyography, EMG) and mandibular movement patterns (electrognat-hography) of deep bite subjects and compare their values with those of subjects with normal occlusion.

Subjects and Methods:

The study consisted of 17 patients with Angle Class II division 2 malocclusion (5 males, 12 females; mean age 21.20±1.7 years) and 10 subjects showing ideal overjet and over-bite values with Angle Class I molar relationship (3 males, 7 females; mean age 22.10±1.3 years). Electrical activity of mas-seter, anterior temporalis, sternocleidomas-toid and digastric muscles were recorded at rest, during clenching and swallowing. Also opening and closing velocities, maximum opening, lateral deviation and deflection rates, centric occlusion to edge to edge articulation and edge to edge articulation to maximum protrusion closure path ways were recorded with “JT3-Jaw Tracker”. Student's t test was used to evalute any differences between groups. Results: EMG values of the masticatory muscles were not significantly different between two groups. When mandi-bular movements were evaluated, only the vertical component of centric occlusion to edge to edge articulation pathway was found longer in deep bite subjects than normal cases (P<0.01).

Conclusions:

The longer pathway from centric occlusion to edge to edge articulation in deepbite subjects can have the risc of creating negative effects on TMJ ligaments and disc. However jaw muscle activities not being different in deepbite cases have shown that muscle forces acting on TMJ are not different from normal cases.