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Experimental occlusal interferences. Part III. Mandibular rotations induced by a rigid interference
N M Rassouli1, L V Christensen
1Marquette University, School of Dentistry, Milwaukee, Wisconsin, USA.
Journal of Oral Rehabilitation
|October 1, 1995
Summary
A rigid bite interference caused specific jaw movements. The contralateral condyle rotated upward, while the ipsilateral condyle showed backward rotation, potentially impacting the temporomandibular joint disc.
Area of Science:
- Dental occlusion
- Biomechanics
- Temporomandibular joint (TMJ) function
Background:
- Occlusal interferences can alter mandibular kinematics.
- Understanding condylar behavior during forceful biting is crucial for TMJ health.
Purpose of the Study:
- To investigate the three-dimensional rotational movements of the mandibular condyles in response to a rigid intercuspal interference.
- To analyze the role of masticatory muscles in mediating these condylar movements.
Main Methods:
- A rigid intercuspal interference was introduced on premolar/molar teeth in 12 subjects.
- Rotational electrognathography was used to measure condylar torque in frontal and horizontal planes during forceful biting.
Main Results:
- All subjects exhibited frontal plane upward rotation of the contralateral mandibular condyle (mean 0.7 degrees).
- 58% of subjects showed horizontal plane backward rotation of the ipsilateral condyle (mean 0.5 degrees).
- Masticatory muscles were inferred to generate positive and negative work to seat/unseat condyles, potentially causing disc issues.
Conclusions:
- Mandibular condylar rotations are significantly influenced by occlusal interferences.
- Ipsilateral masseter muscle activity may decelerate condylar 'unseating', while contralateral activity accelerates condylar 'seating'.
- Condylar 'seating' impact forces may lead to temporomandibular joint disc displacement via negative hydrostatic pressure ('vacuum sticking').