Now is the time to observe and treat dental occlusion
GORDON J. CHRISTENSEN, D.D.S., M.S.D., PH.D.
Dentistry is involved primarily with only three major diseases or conditions: dental caries, periodontal disease and occlusal conditions. Dental caries is the condition most people associate with dental care. Periodontal disease is treated, of course, by periodontists, but not by many general dentists; in general practices, dental hygienists provide most of the clinical service for periodontal disease. General dentists observe occlusal conditions or diseases on a routine basis but, in most cases, do not treat them; rather, prosthodontists and periodontists traditionally have performed most of the clinical care of occlusal problems. Orthodontists, too, treat malocclusion, but they are not involved to a significant degree with the various other pathological conditions related to occlusion.
Are there many people who have occlusal diseases or conditions? It is often stated that most patients have, at one time or another, some form of occlusal disease.1 Our aging population presents more challenges in occlusion than used to be the case, when people died earlier in life. This article describes the various identifiable abnormal conditions of occlusion and makes suggestions relative to the treatment of these conditions.
There are at least six abnormal conditions related to occlusion that appear to be pathologic. However, I am sure that others could be identified. Readers will have their own opinions about the various conditions, and I predict that there will be controversy about the following definitions of occlusal conditions and their treatment.
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BRUXISM
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Excessive tooth grinding is the most prevalent and destructive occlusal condition.2 I estimate that about one-third of the population experiences bruxism or clenching. However, others3,4 have reported bruxism in 5 percent to 100 percent of the general population. Patients subject to bruxism or clenching grind their teeth at various times of the day or night, and usually the tooth wear is catastrophic. Excessive tooth grinding can eliminate canine and incisal guidance in the dentition. The result usually is highly worn teeth, with a relatively flat plane of occlusion, and a group function occlusion in the dentition. If bruxism or clenching is not treated, the centric-occlusion contacts become worn. Patients in these situations have mutilated and unsightly dentitions by the age of 40 years.
What can be done for the bruxing patient? One of the most important methods of preventing bruxism is educating the patient about the condition and its expected consequences. Usually, education reduces daytime bruxism. However, tooth-grinding during sleep is still a problem. Occlusal splints—a treatment method I and others have promoted for many years—help the bruxing patient to reduce or eliminate the damage caused by bruxism. Splints are worn primarily at night, and also during times of psychological stress. Occlusal splints should be a routine treatment in every general practice. Occlusal equilibration also is thought to reduce the tendency of bruxing patients to grind their teeth.
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CLENCHING
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Clenching has been called "centric bruxing." A patient who clenches his or her teeth does not grind them in lateral excursive movements; rather, he or she places the upper and lower teeth together and places pressure on them in centric occlusion, the most interdigitated position. The result of this abusive tooth contact is excessive wear in the centric-occlusion position. Canine rise and incisal guidance become steeper, rather than less inclined as in bruxism. The teeth of a clenching patient have the same quantity of destruction as those of a bruxing patient, but the wear is in centric occlusion instead of in eccentric positions.
On a routine basis, every dentist inadvertently causes primary occlusal trauma when placing restorations in teeth.
Treatment of clenching is similar to that of bruxism. Education of patients is essential to obtain their assistance in preventing further tooth destruction. Occlusal splints worn at night and at times of psychological stress during the waking hours can reduce or eliminate the tooth destruction caused by excessive tooth grinding. Occlusal equilibration often is indicated to reduce the tendency to clench the teeth. If a dentist merely "watches" patients as they wear their teeth down, he or she is practicing supervised neglect and contributing to continued tooth destruction.
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PRIMARY OCCLUSAL TRAUMA
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Many dentists group all types of occlusal trauma into one classification. I prefer to divide them into two:
- – primary occlusal trauma, caused by abnormal loads on otherwise healthy teeth;
- – secondary occlusal trauma, caused when periodontal disease is present as well.
The first of these is primary occlusal trauma. On a routine basis, every dentist inadvertently causes primary occlusal trauma when placing restorations in teeth. It is nearly impossible to place a restoration, crown, or fixed or removable prosthesis so as to re-create the exact anatomy that the teeth had before the treatment. As a result, the restored teeth and the opposing teeth occlude in a slightly different manner from that in which they did previously. This condition also can be caused by orthodontic therapy, trauma and increased bruxism or clenching in a stressful time, or by the natural physiological movement of teeth over time. Teeth in primary occlusal trauma are painful and mobile, and they cause patients concern. Treatment of primary occlusal trauma is simple and effective. It generally consists of occlusal equilibration to evenly redistribute the stress placed on the teeth during chewing or during abnormal contact of the teeth. I encourage dentists to learn the simple techniques of occlusal equilibration.
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SECONDARY OCCLUSAL TRAUMA
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In the presence of periodontal disease, there is loss of support for the teeth and subsequent drifting of teeth into different locations. The occlusal and incisal surfaces of the teeth meet in abnormal relationships, and the same type of occlusal trauma begins again.
How is secondary occlusal trauma treated? The periodontium must undergo periodontal therapy before any long-term stabilization of the occlusion can be expected. Occlusal equilibration may be performed before, during or after periodontal treatment.
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TEMPOROMANDIBULAR DYSFUNCTION
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Everybody talks about temporo-mandibular joint dysfunction, or TMD, but only a few dentists treat it. The reason for non-treatment is the condition’s multifaceted nature and psychological overlay. Most dentists would agree that most short-term TMD is muscular in nature. These muscular TMD cases are the ones that general practitioners should be treating. I approximate (from my 40 years of treating TMD) that they compose nearly 80 percent of the TMD cases that come into a general practice. Usually, pain is present in the muscles of mastication; there is limitation of mouth opening, and a generalized feeling of worry and helplessness on the part of the patient.
Most dentists use occlusal splints as the first and foremost therapy for TMD. After a period of observation, and reduction of the muscle pain, an occlusal equilibration is accomplished to make the teeth come together in a harmonious interdigitated position. Usually, muscular TMD cases can be treated in this manner in a few weeks. More complicated cases involving bone degeneration or chronic long-term pain are far more difficult to treat. Some require surgery, long-term physical therapy or drug administration. I suggest that general dentists should be actively involved in treatment of simple muscular TMD, and that they should refer more complicated cases to other competent practitioners in their geographic area.
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ABFRACTIONS
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Abfraction, associated by many dentists and researchers with occlusal stresses placed on teeth, is becoming well-known. For years, dentists thought the mysterious occurrence of deep slots on facial and sometimes lingual surfaces of teeth were caused by toothbrushing abuse, but current beliefs support the concept that the grooves are caused by facial-lingual movement of teeth during occlusion. If excessive occlusal forces cause these grooves, can we not prevent further degeneration of teeth by placing occlusal splints in the mouths of patients who are likely candidates for abfractions? Practitioners who are knowledgeable about abfractions are using both occlusal equilibration and occlusal splints to prevent abfractions. In my opinion, abfractions should be restored if they are painful, collect food or are unsightly. Otherwise, treatment probably should be some type of preventive occlusal therapy, as previously described.
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CONCLUSIONS
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I have described six types of degenerative occlusal conditions: bruxism, clenching, primary occlusal trauma, secondary occlusal trauma, TMD and abfractions. Currently, in my opinion, practitioners neglect most of these conditions. All of these conditions, in their early stages, can be treated relatively simply by general practitioners. I recommend that dentists become more knowledgeable about the pragmatic aspects of occlusion, and that they treat these conditions on a routine basis in their practices. General dentists should refer patients who have more complex occlusal problems to other practitioners who specialize in those conditions. The important point of this article is that occlusal conditions and diseases should not be neglected by either practitioners or patients.
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Dr. Christensen is co-founder and senior consultant of Clinical Research Associates, 3707 N. Canyon Road, Suite No. 7A, Provo, Utah 84604, and is a member of JADA’s editorial board. He has a master’s degree in restorative dentistry and a doctorate in education and psychology. He is board-certified in prosthodontics. Address reprint requests to Dr. Christensen.
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FOOTNOTES
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The views expressed are those of the author and do not necessarily reflect the opinions or official policies of the American Dental Association.
Educational information on topics discussed by Dr. Christensen in this article is available through Practical Clinical Courses and can be obtained by calling 1-800-223-6569.
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REFERENCES
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- Christensen GJ. Abnormal occlusal conditions—a forgotten part of dentistry. JADA 1995;126(12):1667–8.
- Christensen GJ. Treating bruxism and clenching. JADA 2000;131(2):233–5.
- Shafer WG, Hine MK, Levy BM. A textbook of oral pathology. 3rd ed. Philadelphia: Saunders; 1974:491.
- Schluger S, Yuodelis RA, Page RC. Periodontal disease. Philadelphia: Lea & Febiger; 1977:121.
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BRUXISM
CLENCHING
