Researchers unraveling the etiology of 'meth mouth'

Dental researchers are trying to unravel a complex mix of physical and behavioral factors contributing to "meth mouth," a condition that often develops in the oral cavities of methamphetamine (MA) abusers and can lead to extensive caries, significant tooth decay, rampant periodontal disease, and worse.

A study in this month's Quintessence International (March 2012, Vol. 43:3, pp. 229-237) examined the role of salivary pH of MA abusers and found that salivary quality may play a more important role in meth mouth than previously considered.

"A small number of studies had been published describing 'meth mouth,' but most were limited in their design or were conducted by non-dental personnel," lead author Michele Ravenel, DMD, associate professor at the Medical University of South Carolina's College of Dental Medicine, told DrBicuspid.com. "We were interested in conducting a study using accepted dental indices."

The subjects in the study (n = 28) had abused MA within the last 12 months, versus nonabusing community controls (n = 16). The study had two parts: A questionnaire was administered by psychologists trained in addiction, and an oral exam was conducted by dental professionals with resting and stimulated salivary testing using a saliva check kit.

The questionnaire included questions about duration of MA abuse, frequency, methods of ingestion, oral hygiene, recent dental treatment, and diet. The oral exam consisted of the decayed missing filled surfaces (DMFS) index, a soft tissue examination, and an evaluation of the presence of plaque, calculus, gingival signs, and tongue condition. Whole saliva was then analyzed for resting flow rate, viscosity, resting salivary pH, stimulated salivary volume, stimulated salivary pH, and buffer capacity.

The authors found a significant increase in the overall caries index (DMFS), as well as the decayed surface (DS) and missing teeth indices among meth abusers versus nonabusers, but no significant differences in total FS, root DFS, root DS, or root FS were found. Their findings also support other reports in the literature that MA abusers consume high numbers of carbonated beverages and engaged in long periods of self-neglect, they noted.

Although the researchers acknowledge the small size of the study, they point to two previously unreported findings of possible clinical relevance.

"Significant differences were found in resting pH (more acidic) and buffering capacity (decreased buffering) in meth abusers compared to the nonabuser controls," they wrote. "Both findings are associated with an increased risk for dental caries and may be considered a critical etiologic factor in meth mouth."

'Meth mouth' causes

Such research is important in improving our understanding of what causes meth mouth. The ADA lists the suspected causes as dry mouth, poor oral hygiene, frequent consumption of sugary and carbonated drinks, tooth grinding and clenching, and possibly the acidic nature of MA itself.

In a study in ISRN Dentistry (June 26, 2011), street samples of MA had pH levels from 3.02 to 7.03, with 72% of samples below the critical pH point of 5.6, i.e. able to cause significant damage to tooth enamel if abused by a route that brings MA into contact with the oral cavity.

Although this would seem to indicate that injecting MA rather than smoking or snorting it may lead to less enamel damage, this hasn't been borne out by the research. Researchers at the University of California, Los Angeles (UCLA) reported in the Journal of the American Dental Association that, among abusers of MA, IV users actually had a higher prevalence of oral disease and missing teeth than those who smoked MA, probably due to more advanced addiction and greater self-neglect.

"Those who use MA may make the transition from noninjecting drug use to injecting drug use, as their dependence on MA becomes more severe," Vivek Shetty, DDS, DMD, professor of oral and maxillofacial surgery at the UCLA School of Dentistry and lead author on the JADA study (March 2010, Vol. 141:3, pp. 307-318), told DrBicuspid.com.

"The injected substance has almost 100% bioavailability, and the onset of the drug high is fairly rapid, generally 15 to 30 seconds."

Recognizable pattern of decay

The ADA notes that "meth mouth" tends to resemble early childhood caries but that "a distinct and often severe pattern of decay" can be observed on the buccal smooth surface of the teeth and the interproximal surfaces of the anterior teeth. This recognizable pattern can help dentists to intervene early in the disease process, "long before the condition progresses to the extreme dental decay and destruction reported in the popular media and case reports," Dr. Shetty noted.

The ADA and the other authors recommend topical fluorides and remineralization products to slow the progression of meth mouth, also advising patients to drink water or milk instead of sugary drinks, encouraging dental hygiene, and having resources available to refer the MA patient to drug treatment.

"For patients who have been off of meth for 12 months, comprehensive care is appropriate when combined with treatment for any salivary deficiencies present," says Dr. Ravenel.

Because of the sympathomimetic nature of MA, abusers high on MA are at risk for myocardial ischemia and cardiac dysrhythmias, hypertensive crises, cerebral vascular accidents, and neuroleptic malignant syndrome. General anesthesia and sedation have been associated with sudden death in MA abusers.

Additionally, MA has been shown to potentiate the respiratory depression effects of opioid drugs. Many authors advise avoiding anesthesia, opiates, epinephrine, sedation, or neuroleptic drugs if MA has been used by the patient in the last 24 hours (Oral Diseases, January 2009, Vol. 15:1, pp. 27-37).

"For current meth users," Dr. Ravenel said, "dentists should provide emergent care only. Extreme caution should be taken, as these patients are at risk for adverse cardiovascular events."

Dentists are in a key role to be able to recognize, treat, and possibly intervene in the addiction/disease process, according to Dr. Shetty.

"As tobacco-use interventions by dentists have demonstrated, the dental encounter offers a useful, but underutilized opportunity to initiate motivational counseling interventions," he said.

For MA users seeking to change, the dental deterioration may be symbolic of their drug-using identity and a visible embodiment of the "drug user" persona they want to escape, Dr. Shetty added.

"Helping these individuals regain oral function and a positive oral self-image through dental reconstruction could become an important part of the recovery process and the first step to assisting them recover their lives entirely," he said.