D7 Mechanical Intervention

Topic

Mechanical interventions modify forces, occlusal contacts, or dental and mandibular positions to restore the biomechanical balance of the masticatory system. These interventions include occlusal adjustment, orthodontics, occlusal splints, and orthognathic surgery, each addressing a different imbalance within the masticatory system.

Occlusal adjustment restores the masticatory system's biomechanical balance by selectively reducing—through controlled grinding—premature contacts that concentrate occlusal force on a single point; by eliminating this concentration point, occlusal adjustment allows the force to be redistributed across multiple contacts, mimicking an occlusion free of premature contacts.

Orthodontics alters tooth positions by applying controlled forces via a system of brackets and archwires; this system generates forces and moments on each tooth, triggering the alveolar bone remodeling required for tooth movement. The optimal orthodontic force to initiate this remodeling without damaging the tooth's supporting tissues ranges from 50 to 300 grams; below this range, the force is insufficient to trigger remodeling, while above it, the force can damage the periodontal ligament and alveolar bone rather than remodeling them in a controlled manner.

An occlusal splint protects the masticatory system during bruxism using an acrylic device placed between the upper and lower teeth; this device increases the surface area over which bruxism forces are distributed and cushions impacts between teeth, thereby reducing the stress transmitted to both the teeth and the temporomandibular joint. Orthognathic surgery corrects severe skeletal discrepancies by surgically repositioning the jaws—something neither occlusal adjustment nor orthodontics can achieve on their own, as both act upon the teeth rather than the jawbones themselves. To plan this repositioning, orthognathic surgery relies on cephalometric planning: cephalometric reference points on the maxilla and mandible are identified, the current position of these points is compared with the position they should occupy post-surgery, and the difference between the two positions represents the exact surgical movement to be performed.

Collectively, occlusal adjustment, orthodontics, occlusal splints, and orthognathic surgery address the same objective at different levels: occlusal adjustment corrects the distribution of occlusal force across existing contacts; orthodontics and orthognathic surgery reposition the teeth or jaws causing the imbalance; and occlusal splints protect the masticatory system while that imbalance persists. Thus, these mechanical interventions—each in its own way—restore the biomechanical balance of the masticatory system mentioned at the beginning of this description.

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