Purpose: Physiological (dental): To compare prevalence of tooth wear in stimulant users and non-stimulant users.

Design: Retrospective (non-experimental) between-subjects design, with drug use (use of ecstasy and/or amphetamines) serving as a between-group factor, with all participants completing drug use q questionnaires and receiving dental examinations.

Subjects: 13 users of ecstasy, stimulants or both drugs and 13 non-drug using controls attending the University of Leeds (England) and recruited via advertisements posted around a university campus and in student publications. Matching - Non-drug using controls were matched with ecstasy and stimulant users on age and gender, and education.

Criteria for Inclusion - Ecstasy and Stimulant Users - Self-reported use of ecstasy, stimulants (e.g. amphetamine, cocaine) or both on at least 10 occasions. Non-Drug Users - No self-reported use of ecstasy or stimulants during lifetime, and good age and gender match for the ecstasy and stimulant users. All Groups - Being a university student, having taken ecstasy, stimulants or both drugs on 1 to 10 occasions.

Drug Use Parameters - Ecstasy and stimulant users reported total (lifetime) use of one or more of these drugs in the range of 10 to over 80 times (no average use provided). No information is provided on average dose per use, frequency of use, duration of use or time since last use, and drug use was verified through self-report only. Other drugs - No information is provided on use of other drugs.

Group Demographics and Matched Variables - The authors matched non-drug using controls on age, gender and being a university student, apparently selecting non-drug users on the basis of how well they matched ecstasy and stimulant user participants. Gender, as M/F ratio - Ecstasy and stimulant users, 8/5; non-ecstasy or stimulant users, 8/5. Age - Ecstasy and stimulant users and non-drug users were all between ages 18 to 23 years, with an (overall) average age of 20.4 +/- 1.6. Education - Ecstasy and stimulant users and non-drug user controls were university students (13-15 years of education).

Measures: Dental Examination - Teeth were examined for tooth wear visually, using the Smith Knight tooth wear index, with all examinations performed by one examiner. (It is unclear whether the examiner was blind to participant condition).

Questionnaire - Drug use and other potential sources of tooth wear were measured via questionnaire containing items on consumption of acidic fruit, carbonated ("fizzy") drinks, known bruxism, dry mouth, frequent vomiting (regurgitation) and participating in competitive sports. Drug use items asked about weekly, monthly and lifetime use of alcohol, tobacco, cannabis, amphetamines, ecstasy and cocaine.

Analyses: Dental Examination - Teeth were grouped into four areas; upper canine to canine, lower canine to canine, upper first molar and lower first molar. Degree of tooth wear was then examined via one-way analysis of variance (ANOVA), with drug use (ecstasy and / or stimulant use versus no reported use of either drug) serving as the between-subjects factor. 4 analyses were performed for each group of teeth, and mean scores were ascribed to teeth by dividing total tooth wear scores by the number of each teeth in a grouping (for instance, 6 in canine to canine). Probability value was not stated but appears to have been 0.05.

Questionnaire - Possible differences in frequency of common risk factors for tooth wear (such as consuming citrus fruit or competitive swimming) were compared across groups (ecstasy and stimulant users and non-drug users) via chi-square statistic. Probability value not reported, but presumed to be 0.05.

Results - Significant Differences Found: Dental Examination - Ecstasy and stimulant users had significantly greater tooth wear on their lower first molars than controls reporting no ecstasy or stimulant use. (There was a trend for ecstasy and stimulant users to have greater tooth wear on the upper first molars, but this did not reach statistical significance)

Results - No Significant Differences: Questionnaire - Ecstasy and stimulant users did not significantly differ from non ecstasy or stimulant users on prevalence of any of the common risk factors for tooth wear listed in the questionnaire.

Dental Examination - Amount of tooth wear on upper and lower canines was similar in ecstasy and stimulant users and non-ecstasy or stimulant using controls. (While there was a trend for greater tooth wear on the upper molars of ecstasy and stimulant users, these findings did not reach statistical significance.)

Overall Effects: Amount of tooth wear on the lower first molars of university students who reported having used ecstasy, stimulants or both drugs on at least 10 occasions was higher than age and gender-matched controls who had never used any of these drugs. However, level of tooth wear on upper first molars, and on both upper and lower canines was similar in both groups. Increased tooth wear in ecstasy and stimulant users could not be explained by increases in any of the most common risks for tooth wear, such as consumption of carbonated beverages or frequent vomiting. Taken together, these results suggest that tooth wear resulting from use of ecstasy or stimulants arose from grinding of the posterior teeth, probably during drug-induced bruxism or jaw clenching. However, the authors state that it would be inappropriate to treat an observation of increased tooth wear on lower first molars as evidence of drug use, as tooth wear can be produced by a number of factors.

Comments: This is the second study formally comparing tooth wear in a sample of ecstasy and stimulant users with tooth wear seen in a sample reporting no use of these drugs. Findings in this study are in agreement with previous studies (Duxbury 1993; Milosevic et al. 1999) reporting increased tooth wear in ecstasy and stimulant users. While the study used age and gender-matched controls, small sample sizes were used, and no attempts were made to correlate lifetime ecstasy and stimulant use with amount of tooth wear. Future research should examine the relationship between specific drug use parameters, such as frequency or duration of use, and signs of dental wear.