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When the maxillary and mandibular dental arches approach each together, as they do, for example, during chewing or at rest, the relationship between the opposing teeth is referred to as occlusion. If this occlusal relationship is not balanced properly it may result in pain, tenderness and even mobility of the affected teeth.
When the natural course of trauma, disease and dental treatment alters an individual's occlusion by removing or changing the occlusal (biting) surface of any of the teeth, that individual's teeth will come together, or occlude, differently, and their occlusion will change. When that change is detrimental to the manner in which the teeth occlude, the patient is said to possess a traumatic occlusion. Traumatic occlusion may cause a thickening of the cervical margin of the alveolar bone and widening of the periodontal ligament, although the latter is not pathognomonic for this condition.
Microscopically, there will be a number of features that accompany occlusal trauma:
It was concluded that widening of the periodontal ligament was a "functional adaptation to changes in functional requirements".
Clinically, there are a number of physiologic results that serve as evidence of occlusal trauma:
There are two types of occlusal trauma, primary and secondary.
Primary occlusal trauma occurs when greater than normal occlusal forces are placed on teeth, as in the case of parafunctional habits, such as bruxism or various chewing or biting habits, including but not limited to those involving fingernails and pencils or pens.
The associated excessive forces can be grouped into three categories. Excesses of:
Secondary occlusal trauma occurs when normal occlusal forces are placed on teeth with compromised periodontal attachment, thus contributing harm to an already damaged system. As stated, secondary occlusal trauma occurs when there is a compromised periodontal attachment and, thus, a pre-existing periodontal condition.
Teeth are constantly subject to both horizontal and vertical occlusal forces. With the center of rotation of the tooth acting as a fulcrum, the surface of bone adjacent to the pressured side of the tooth will undergo resorption and disappear, while the surface of bone adjacent to the tensioned side of the tooth will undergo apposition and increase in volume.
In both primary and secondary occlusal trauma, tooth mobility might develop over time, with it occurring earlier and being more prevalent in secondary occlusal trauma. To treat mobility due to occlusal trauma, whether it be primary or secondary, the affected teeth are splinted together and to the adjacent teeth so as to eliminate their mobility.
In primary occlusal trauma, the etiology, or cause, of the mobility was the excessive force being applied to a tooth with a normal attachment apparatus, otherwise known as a periodontally-uninvolved tooth. The approach should be to eliminate the etiology of the pain and mobility by determining the causes and removing them; the mobile tooth or teeth will soon cease exhibiting mobility. This could involve removing a high spot on a recently restored tooth, or even a high spot on a non-recently restored tooth that perhaps moved into hyperocclusion. It could also involved altering one's parafunctional habits, such as refraining from chewing on pens or biting one's fingernails. For a bruxer, treatment of the patient's primary occlusal trauma could involve selective grinding of certain interarch tooth contacts or perhaps employing a nightguard to protect the teeth from the greater than normal occlusal forces of the patient's parafunctional habit. For someone who is missing enough teeth in non-strategic positions so that the remaining teeth are forced to endure a greater per square inch occlusal force, treatment might include restoration with either a removable prosthesis or implant-supported crown or bridge.
In secondary occlusal trauma, simply removing the "high spots" or selective grinding of the teeth will not eliminate the problem, because the teeth are already periodontally involved. After splinting the teeth to eliminate the mobility, the etiology of the mobility (in other words, the loss of clinical attachment and bone) must be managed; this is achieved through surgical periodontal procedures such as soft tissue and bone grafts, as well as restoration of edentulous areas. As with primary occlusal trauma, treatment may include either a removable prosthesis or implant-supported crown or bridge.