I am writing concerning the "Point/Counterpoint" articles in October JADA,1–2 discussing occlusion as it relates to periodontal disease.
Both sides have similar definitions of the term "occlusal discrepancies." And both seem to have basic agreement that "occlusal forces" may contribute to the progression, but not initiation, of periodontal disease, even though they differ somewhat in defining the exact circumstances in which occlusion-directed therapy is indicated. Unfortunately, on their road to this agreement, both sides freely use other terms in their arguments about occlusion without clear definitions or descriptions, so that the readers are left to interpret for themselves as to their meaning and significance to the arguments.
In fact, some of the occlusion-related terms used in the two articles often mean slightly, or completely, different things to different practitioners. Citing from the two articles, these terms include "occlusal forces," "vector of forces," "occlusal stress," "occlusal trauma," "parafunctional habits," "occlusal adjustment," "occlusal analysis," "centric relation," "balancing contacts," "working or nonworking contacts," "occlusal wear," "traumatogenic occlusion" and "excessive occlusal contact."
Thus, beyond their tentative agreement on indications for occlusal therapy, both articles serve to muddy the waters of an already controversial, and confusing, subject by freely using undefined and often ambiguous terms.
This confusion aside, it amazes me that our profession slices, dices, dissects and argues about "occlusion," when it is axiomatic and basic, even for beginning dental students, that teeth in normal function should not contact, except during a chewing or swallowing action. And, in fact, there is usually food between the teeth until the final stages of chewing. At all other times, the mandible should physiologically be in the "rest position," with varying degrees of separation between the maxillary and mandibular teeth.
To believe that normal occlusal function causes trauma in excess of adaptability, we have to believe that the occasional light momentary tooth-to-tooth contact when swallowing, and the occasional momentary heavier contact that might occur during chewing, are capable of producing trauma to the teeth and/or periodontium.
Even assuming that there would be direct, heavy tooth contact during every chewing movement, I am not aware of studies showing that such normal functional tooth contact is capable of producing traumatic effects.
If this is correct, then it follows that the major deleterious impacts that might occur as a result of occlusal relationships and forces can occur only if there is parafunctional tooth contact, sometimes in terms of clenching, but more often related to horizontal mandibular bruxing movements.
It would also follow that occlusion-related therapy when treating periodontal disease or temporomandibular dysfunction should be aimed at eliminating any parafunctional bruxing causes, not in creation of a situation in which the effects of parafunctional tooth contact are mitigated using treatments (of varying degrees of invasiveness) aimed at minimizing the degree of trauma or at correcting its effects. Stop the noxious habits, and effects stop. No cause, no effect.
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