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A Taste-Based Approach to the

Prevention of Bruxism

Descriptor Key Words: Bruxism, Teeth Grinding, Teeth Clenching, Treatment, Dental Appliance, Feedback, Taste Aversion, Case Study

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Some 5-20% of all people excessively grind or clench their teeth, thereby exerting powerful forces on teeth, gums, and joints. Thus, at the very least, one out of twenty people brux; most likely, one out of four does. Inarguably, then, bruxism is a widespread behavioral pattern which adversely affects a significant fraction of the world's people.

All forms of bruxism entail forceful contact between the biting surfaces of the upper and lower teeth. In grinding and tapping this contact involves movements of the mandible and unpleasant sounds which can often awaken sleeping partners and even people sleeping in adjacent rooms. Clenching (or clamping), on the other hand, involves inaudible, sustained, forceful tooth contact unaccompanied by mandibular movements.

With no consciousness of the action, and with no food to moderate it, the forces applied during sleep bruxism may exceed by a factor of three the forces generated during chewing (Castaneda, 1991, p. 46). Other estimates put these forces at ten times the pressure of chewing—powerful enough to crack a walnut (Murray, 1998).

Although not a life-threatening condition, chronic bruxism often impairs the quality of life of affected individuals. In advanced stages, the condition might be accompanied by tooth sensitivity, abrasion, fractures, mobility, or loss (Mcguire and Nunn, 1996); dental caries; alveolar bone loss; headaches; earaches and hearing loss (Bubon, 1995); adverse, cumulative, irreversible effect on dental implants (Perel, 1994) and aesthetic restorations; diminished facial height which may in turn change one’s appearance and cause mandibular overclosure (Thompson, Blount, and Krumholtz, 1994); hypertrophy of the masseter muscle, which in turn can adversely affect one’s appearance (Rijsdijk, Van Es, Zonneveld, Steenks, and Koole, 1998) or block the parotid duct and lead to parotitis-like or sialolithiasis-like syndromes (Thompson, Blount, and Krumholtz, 1994); and higher levels of mercury in the blood (Isacsson, Barregard, Selden, and Bodin, 1997) of some bruxers with mercury fillings. Moreover, bruxism is probably a leading cause of temporomandibular disorders (Glaros, Tabacchi, and Glass, 1998), a condition which can "devastate its victim" (Goldman, 1992, p. 191). Grinders (but not clenchers) suffer from social discomfort as well, for many people find the grinding sound unpleasant, irritating, or disturbing (Blount et al., 1982; Watson, 1993).

The etiology of bruxism is controversial and uncertain (Ellison and Stanziani, 1993; Thompson, Blount, and Krumholtz, 1994). At present, the causes are suspected to be many, to overlap each other, and to vary from one patient to another. Putative causes include stress, personality types, allergies, nutritional deficiencies, malocclusion, dental manipulations, introduction of foreign substances into the mouth, central nervous system malfunction, drugs, deficient oral proprioception, and genetical factors.

The diagnosis of bruxism also presents difficulties. In this context, it is convenient to distinguish between grinders and clenchers. In the case of grinders who share living quarters with other people, reports of bruxism might be fairly reliable (but see Marbach et al., 1990). For grinders who live alone, and for clenchers, diagnosis is primarily based on tooth attrition. In research settings, the bruxcore plate is sometimes used, but this plate involves additional expense and is not necessarily reliable (Pierce and Gale, 1989).

Despite almost one century of research, and despite well over one thousand publications on the subject, "no entirely satisfactory treatment has been identified" (Ellison and Stanziani, 1993). Van Dongen (1992, p. 16) concludes: "Today’s practitioners can avail themselves of various management strategies to control bruxism, but may not be able to stop it."

The most common treatment involves the time-honored (e.g., Karolyi, 1906, cited in Ramfjord, 1961, p. 23; Matthews, 1942) occlusal splint (Rugh et al., 1989). In the United State alone, some 1.6 million such nightguards are annually prescribed by dentists in an effort to combat bruxism (Pierce, Weyant, Block, and Nemir, 1995). Yet the mouthguard "does not actually prevent or cure the bruxism, but it will prevent damage to the teeth when bruxism occurs" (Hartmann, 1994). According to Rugh et al. (1989), splint therapy is effective at first, but "the usual trend with longer treatment is to lose its effects. In other words, one usually sees a dramatic decrease or increase in EMG activity the first few nights of splint usage, followed by a gradual return to pretreatment EMG values." The limited effectiveness of the traditional splint is also "borne out by the common clinical finding that patients may bite large teeth marks into night bite guards and frequently fracture appliances" (Trenouth, 1979). Moreover, the use of such splints may sometimes adversely affect the patient’s occlusion, e.g., cause an open bite (Ahlin, 1991; Wiygul, 1991), cause tooth decay, and precipitate a degenerative joint disease (Messing, 1991, pp. 437-8).

Less widely used approaches include stress management, hypnotherapy, massed negative practice, drugs, nutritional supplements, exercises, occlusal adjustment, intraoral vacuum reduction (Long, 1998), wakeful biofeedback, and machine or human aversive biofeedback. But these approaches are controversial and only provide, at best, partial remediation.

At least two lines of evidence suggest that taste feedback may be conveniently used to prevent bruxism.

First, extensive work in conditioned taste aversion—despite its many differences from the approach described in this note—raises the intriguing possibility that unlearned, instinctive taste aversion can serve as a powerfully aversive, readily associable, stimulus in sleeping bruxers (Bernstein, 1991; Chambers and Bernstein, 1995; Garcia, Ervin, & Koelling, 1966). Second, known therapeutic practices also suggest that taste aversion may be used to treat bruxism. Thus, the childhood syndrome of finger sucking can sometimes be treated successfully by applying spicy liquid or denatonium benzoate to the fingers (cf. Josell, 1995; Umberger & Reenen, 1995; U.S. Pat. No. 5,474,093). ).

Treatment Procedure

This section outlines the procedure for the intraoral release of an unpleasant-tasting, safe, substance whenever a patient attempts to brux, thereby drawing the patient's conscious attention to, and precluding, teeth clenching or grinding.

Following initial consultation with a bruxing patient, dental impressions of both lower and upper teeth are taken.

The impressions are sent to a lab, where an appropriate removable dental appliance is constructed (see Figs. 1-7).

Also during the initial consultation, an aversive substance is agreed upon. The substance is derived from one or more natural or synthetic, palatable, materials such as hot peppers (capsaicinoids), horseradish, quinine, mustard, ginger, garlic, onion, salt, or denatonium benzoate.

The aversive substance is dissolved or suspended in water, vinegar, or other safe, digestible, barely-compressible, fluids.

At present, the liquid-filled containers, bags, or capsules (see Figs. 1, 5-7) are constructed, with a commercial impulse sealer, from clear, one-inch wide, polyethylene plastic tubing (commercially available for packaging food products, and hence not containing plasticizers or latex). Not including the sleeves, the capsules are approximately 8 mm wide, 12 mm long, and .07 mm (3 mil) thick.

The liquid is then inserted into, and sealed in, the sleeved capsules, so that each capsule contains little or no air. At its center, the liquid is high enough (roughly 4 mm) to rupture the capsule when the user clenches or grinds, but is not so high as to seriously inconvenience the user or prevent lip contact. The capsule only bursts when the user attempts to bring the maxillary and mandibular teeth together, but not upon mere tooth contact. Experience suggests that such capsules contain enough liquid to reach many taste buds, but not enough to cause any discomfort other than the one associated with unpleasant taste.

Before going to sleep or whenever bruxing is suspected to occur, the patient attaches two liquid-filled sleeved capsules (Fig. 1) to the removable appliance and inserts the appliance into the mouth (Figs. 4, 5). The appliance is so designed that the capsules are positioned between the lower and upper teeth and are evenly balanced on each side of the mouth (see Fig. 6). Whenever the user attempts to brux, at least one capsule releases its disagreeable liquid.

The choice of substance and its concentration is subject to ongoing revision. If it is too aversive, the concentration is lowered or another substance is tried. If the patient wakes up with ruptured, empty capsules (suggesting that the break-up of the capsules failed to induce arousal), the concentration is raised or other substances are tried.

To diagnose bruxism and convince patients that they do indeed grind, the sleeved capsules above may be stuffed with ridged dental wax (instead of liquid), joined to the same appliance, and inserted into the mouth before going to sleep. Structural deformations in the wax then serve as a qualitative indicator that bruxing indeed is occurring. Thus, both diagnosis and treatment can be effected by essentially the same appliance. It must be noted, however, that, owing to obvious methodological difficulties, this procedure should not be used as the sole indicator of the condition. For example, like the bruxcore plate, the dental appliance described here may alter the very behavior it tries to measure (Pierce and Gale, 1989)

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A 52-year-old man had been told in passing by three dentists over a period of twelve years that he was grinding his teeth. The patient offered the following explanation for not taking his dentists’ diagnosis seriously. To begin with, he said, he was repeatedly told that he was grinding his teeth (not clenching), yet his wife assured him that this was not the case. Also, none of the dentists actually pointed to the damaged teeth, compared them to normal teeth, discussed treatment options, or explained the likely course of this parafunction if it were allowed to continue. So for a few years the patient neglected this condition.

He realized he had a problem only some five or six years after he was first diagnosed with the condition of sleep bruxism, when the damage to his molars (flat short back teeth, exposed dentin, and crowns) became clear even to his untrained eyes.

Some six years after the first signs of sleep bruxism were noted, at the patient's insistence and initiative that something be done to control the problem, four different dental appliances were suggested, and tried, in succession. The first was a partial removable appliance which covered only two lower right molars and prevented tooth contact and which the patient wore every night for some three months. When this failed, he tried a hydrostatic splint—a water-filled removable dental appliance which is said to equalize bruxing pressure and thus moderate it (Lerman, 1987). But this splint did not control the symptoms, kept moving around while he slept, sometimes even being ejected from the mouth. He then tried a soft mandibular splint, which also failed. This was followed by the standard treatment—a hard, acrylic splint attached to the maxillary teeth.

To cure his sleep bruxism, he was instructed to always wear this splint during sleep (but never during waking hours). He wore this splint nightly for about a year. He now believes that this hard splint permanently and irreversibly damaged his bite, changing his bite in this case from a near-perfect one to an annoying anterior bite (at maximum tooth contact, front teeth are about 2.5 mm apart). Photographs taken before splint use confirm the absence of open bite at that time. No other side effects were noted, although the patient reported sleep discomfort while wearing the splint and experienced difficulties keeping the splint clean and odor-free.

In this case, the splint—like its predecessors—did not ameliorate the condition of sleep bruxism. Still wearing the hard splint during every sleeping moment, the patient began to experience the characteristic TMD click and sore jaws, especially upon waking. This was followed by frequent and severe short (5 seconds or less) daytime aches inside his right ear. A subsequent examination revealed a modest degree of hearing loss in that same ear.

At this point, the patient sought the advice of two dentists, a family physician, and two ear-nose-throat specialists. Neither the patient nor these specialists traced the hearing loss and bouts of earaches to the known condition of bruxism (cf. Bubon, 1995). Following these specialists' advice, he tried ear drops but declined a recommendation to undergo nose surgery. The painful earaches continued, unabated.

A casual conversation with the patient led to the suggestion that the earaches and hearing loss might be traceable to the known condition of bruxism. At that point, he opted for the taste-based approach. The first few nights were stressful, owing, first, to discomfort about the inevitable release into the mouth of the unpleasant-tasting liquid. There were also many interruptions of sleep—over ten per week in the first month. But as the weeks passed, he got used to the idea and slept soundly, while the incidence of waking episodes rapidly declined. By the third month, a bag would explode and wake him up only about twice a week, often when just falling asleep. From the fourth through the eighth months, on average, less than one waking episode per week has been reported. So, with the exception of five days (see below), the patient has been wearing the appliance for eleven months, during which time prolonged bruxing was impossible and the earaches and sore jaws vanished. The TMJ click, as well, is almost gone (no measurements were taken, however).

The patient reports that the taste-based appliance was more comfortable to sleep with than the hard splint, and far more effective. For the first time in twelve or more years, he was able to cease this destructive and frustrating parafunction. The patient was particularly concerned about the numbing earache, the possibilities of premature hearing loss (which he felt might be traceable to bruxing), developing a temporomandibular disorder (TMD), and continuing to spend thousands of dollars on crowns and fillings, which events now appear unlikely.

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Several lines of evidence suggest, but do not prove, a cause-effect relationship between the taste-based treatment and cessation of symptoms. To begin with, during this eight-month period, the patient was away from home on two occasions, spending, respectively, two and three nights without the appliance. In three of the five days following these absences, the earaches and sore jaws returned. This was in striking contrast to the hundreds of days which followed successful wear of the appliance, and which were symptom free.

Also, bruxism in this case was chronic and persistent. It seems unlikely that it would have vanished just at the moment treatment began. Besides, for at least one year before taste-based treatment began, the patient would consistently wake up with sore jaws and would often experience earaches and ringing during the day. These symptoms vanished from the very beginning of treatment, and, as we have seen, only returned in three of the five days when the appliance was not worn. It also seems unlikely that success in this case can be ascribed to a placebo effect, for other, more conventional, treatments failed to exert this effect.

Moreover, the patient reported no major upheavals in his life (e.g., lifestyle changes, use of medications, bereavement, loss of job) which could lead to the spontaneous, treatment-unrelated, cessation of bruxism symptoms just when the taste-based treatment began.

In common with most therapeutic approaches, the taste-based approach described here has its fair share of inconveniences; only strongly motivated, chronic bruxers are likely to use it. Another drawback of this taste-based approach—and of all other biofeedback approaches—is their essentially behavioristic character. Such approaches concede our ignorance about the etiology of bruxism and proceed to treat the behavior itself. Experience suggests that such surface approaches are often successful, but they are invariably met with understandable resistance, especially from those who are committed to the notion that a worthwhile cure must remove the underlying cause. Also, the very novelty of the approach might detract from its initial appeal to many clinicians and patients.

Unlike some other approaches, the taste-based approach strives to eliminate bruxing behavior. Unlike EMG-activated approaches, it is directed to the bruxing act itself and cannot therefore be confused with other types of orofacial movements unrelated to bruxism (Miguel et al., 1992). Unlike biofeedback approaches which rely on sound alarms or electric shocks, the approach described here relies on the more natural (for intraoral behavior), more convenient, less habituable—and hence potentially more effective—aversive stimulus.

Special attention has been paid to maximizing safety and minimizing side effects. Repeated tests of hundreds of the polyethylene capsules show that they always remain attached to the appliance, and that, when they rupture, they remain as a single piece and are never torn into fragments. Moreover, repeated tests show that the small quantity of liquid that is being released, while sufficient to awake a sleeping user, never causes gagging or other untoward effects.

A detailed study comparing the side effects of the traditional splint to our appliance is yet to be carried out. But because our appliance resembles more closely the appliance customarily used by children, it is, in all likelihood, not associated with the most common complications of traditional splint therapy: occlusal changes and severe degenerative joint disease (Messing, 1991, pp. 437-8).

In view of the uncertainties surrounding the treatment of bruxism, the moderate effectiveness of established therapies, and bruxism's high incidence, a large scale, controlled, study comparing the effectiveness of old and new therapeutic modalities is long overdue.

The clinical approach described here involves the construction of a customized, safe, minimally-intrusive, dental appliance. In an optional, confirmatory, diagnostic phase, two identical, ridged, dental wax pellets are inserted into polyethylene sleeved capsules. The capsules are then attached to the appliance, which the user wears whenever bruxism is suspected to occur. After the existence of bruxism is confirmed through markings and structural alterations in the wax, the same appliance is used to lodge two identical, small, sleeved, plastic capsules filled with a barely-compressible, sealed, unpleasant-tasting, solution. When users clench or grind their teeth, at least one of the capsules ruptures. Users wake up, rinse their mouth, replace the collapsed capsule, and resume sleep. Similarly, when daytime users unconsciously brux, one or two capsules rupture and alert them to the occurrence of bruxing. This approach has been successfully used to treat one chronic bruxer over an eight-month period. Success in this case, combined with other characteristics of taste-based treatments—convenience, appropriateness as an intraoral aversive stimulus, effectiveness in other experimental and clinical settings—invite a large-scale, quantitative, study.

Needless to say, this approach can be combined with such other approaches as magnesium supplements, stress reduction, or hypnotherapy.

The research described in this paper owes much to the cheerful, extremely competent, assistance of Shere Kahn. In particular, the appliance of Fig. 7 has been designed by Shere.

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The research described in this note owes much to the cheerful, competent, assistance of Donna Nissani and Shere Kahn. In particular, the appliance of Fig. 7 has been designed by Shere.

Address all correspondence to: Dr. Moti Nissani, Rm. 2134, CLL, 5700 Cass Ave, Wayne State University, Detroit, MI 48202, USA (moti.nissani@wayne.edu).