Dawson's Occlusion: The design of the masticatory system
The goal for all occlusal therapy is a peaceful neuromusculature. If there is any loss of equilibrium, the muscle will try to regain equilibrium. In a war between teeth and muscle, the teeth will lose. This manifests as tooth wear, mobility, fracture and movement.
It is essential to understand the role of the TMJs in occlusal design. As clinicians we must ensure that the TMJ in a reproducible and physiologic position (Centric relation) before the occlusion can be properly assessed and treated. Dawson explains the importance of occlusal harmony by taking a mechanical perspective on the design of the masticatory system.
In the design of the teeth, it is important to note that the Jaws and TMJ developed before the occlusion therefore, the occlusion must fit into the preestablished maxillomandibular relationship.Correct phyisologic jaw position must therefore be determined before we can determine the correct alignment and occlusal relationship of the teeth.
The primary requirements for successful occlusal therapy:
1. Comfortable and stable TMJs: As before, the treatment starts at the TMJ. If the TMJs aren't recorded in CR, any analysis or treatment will not be harmonious or stable.
2. Anterior teeth: In harmony with the envelope of function i.e lips, tongue and occlusal plane.
3. Posterior teeth: non interfering with anterior guidance or the TMJs.
These three requirements form a triad that is in balance. Any disharmony in one part of the triad will affect the other two and will also cause discoordination the fourth factor which is the muscle.
The concept of the perfect occlusion
The idealised occlusion is visualised below. This will have the optimum effect on the posterior, anterior teeth, TMJs and muscle.
It features:
1. Simultaneous equal intensity contact on all teeth when in CR
2. Contact on posterior teeth is on cusp tips
3. Anterior teeth have continuous contact from CR to incisal edges as the mandible moves forwards and laterally.
4. Posterior disocclusion in all excursions from CR as it causes elevator muscles to shut off reducing the forces on the TMJ and anterior teeth. Conversely, if there is a posterior interference on excursions, the elevator muscles will be activated when the TMJ is not in the physiologic position leading to muscle instability
It is essential to understand the role of the TMJs in occlusal design. As clinicians we must ensure that the TMJ in a reproducible and physiologic position (Centric relation) before the occlusion can be properly assessed and treated. Dawson explains the importance of occlusal harmony by taking a mechanical perspective on the design of the masticatory system.
In the design of the teeth, it is important to note that the Jaws and TMJ developed before the occlusion therefore, the occlusion must fit into the preestablished maxillomandibular relationship.Correct phyisologic jaw position must therefore be determined before we can determine the correct alignment and occlusal relationship of the teeth.
The primary requirements for successful occlusal therapy:
1. Comfortable and stable TMJs: As before, the treatment starts at the TMJ. If the TMJs aren't recorded in CR, any analysis or treatment will not be harmonious or stable.
2. Anterior teeth: In harmony with the envelope of function i.e lips, tongue and occlusal plane.
3. Posterior teeth: non interfering with anterior guidance or the TMJs.
These three requirements form a triad that is in balance. Any disharmony in one part of the triad will affect the other two and will also cause discoordination the fourth factor which is the muscle.
The concept of the perfect occlusion
The idealised occlusion is visualised below. This will have the optimum effect on the posterior, anterior teeth, TMJs and muscle.
1. Simultaneous equal intensity contact on all teeth when in CR
2. Contact on posterior teeth is on cusp tips
3. Anterior teeth have continuous contact from CR to incisal edges as the mandible moves forwards and laterally.
4. Posterior disocclusion in all excursions from CR as it causes elevator muscles to shut off reducing the forces on the TMJ and anterior teeth. Conversely, if there is a posterior interference on excursions, the elevator muscles will be activated when the TMJ is not in the physiologic position leading to muscle instability
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