Legal psychoactive substances as risk factors for sleep-related bruxism: a nationwide Finnish Twin Cohort study.

AIMS: Different psychoactive factors including alcohol, coffee and tobacco, are considered as risk factors for bruxism. Often, heavy drinking and generous intake of coffee are correlated with smoking. Interactions between these agents may confound studies. The aim was to investigate the possible independent effects of drinking alcohol and coffee consumption on the occurrence of bruxism. METHODS: Data derived from the Finnish Twin Cohort study consisting of 12,502 twin individuals (45.6% men, 54.4% women, mean age 44 years) born during the 1930-1957. The twins responded to a questionnaire sent in 1990 (response rate of 77%) consisting of 103 multiple-choice questions, seven dealing with tobacco use, four on alcohol use, one about coffee consumption and two with bruxism. RESULTS: Increasing alcohol intake raised the risk for weekly bruxism even when adjusted for smoking status [heavy drinking odds ratio (OR) 1.9; 95% CI 1.23-2.84, binge drinking OR 1.6; 95% CI 1.28-2.12, and passing-out due to excessive alcohol intoxication at least twice within the previous year OR 1.5; 95% CI 1.09-2.18]. The situation was similar to that for coffee consumption of more than eight cups per day (OR 1.4; 95% CI 1.01-1.98). Interaction analyses for 'smoking with risk factors' revealed no statistically significant interactions. Current smoking was an independent risk factor for bruxism in all models (OR 2.3-2.7). CONCLUSION: Given the observed associations between alcohol drinking, binge drinking, passing-out due to excessive alcohol intake and coffee consumption, the results support our hypothesis of an independent association of both alcohol use, and coffee consumption with bruxism.

Bruxism is associated with nicotine dependence: a nationwide Finnish twin cohort study.

OBJECTIVES: To investigate the association of smoking with bruxism while controlling for genetic and environmental factors using a co-twin-control design. Especially, the role of nicotine dependence was studied in this context. METHODS: The material derives from the Finnish Twin Cohort consisting of 12,502 twin individuals who responded to a questionnaire in 1990 (response rate of 77%). All were born in 1930-1957, the mean age being 44 years. The questionnaire covered 103 multiple choice questions, 7 dealing with tobacco use and 22 with sleep and vigilance matters, including perceived bruxism. In addition, a subsample derived from the Nicotine Addiction Genetics Finland Study containing 445 twin individuals was studied. RESULTS: In age- and gender-controlled multinomial logistic regression, both monthly and rarely reported bruxism associated with both current cigarette smoking (odds ratio [OR] = 1.74 and 1.64) and former cigarette smoking (OR = 1.64 and 1.47). Weekly bruxism associated with current smoking (OR = 2.85). Current smokers smoking 20 or more cigarettes a day reported weekly bruxism more likely (OR = 1.61-1.97) than those smoking less. Among twin pairs (N = 142) in which one twin was a weekly bruxer and the cotwin a never bruxer, there were 13 monozygotic pairs in which one twin was a current smoker and the other twin was not. In all cases, the bruxer was the smoker (p = .0003). Nicotine dependence associated significantly with bruxism. CONCLUSIONS: Our twin study provides novel evidence for a possible causal link between tobacco use and bruxism among middle-aged adults. Nicotine dependence may be a significant predisposing factor for bruxism.

Genetic and environmental factors in oral health among twins.

To date, studies on the contributions of genetic factors to oral health have been inconclusive. We hypothesized that major dental diseases show a significant genetic component. The study was based on self-reported oral health among young adult twins. The data were derived from the fourth wave of the longitudinal FinnTwin16 study, in which participants completed a questionnaire in 2000-2002 enquiring about the number of filled teeth and the prevalence of gingival bleeding. We used quantitative genetic modeling, based on the genetic similarity of identical and non-identical twins, to calculate the most probable model for both filled teeth and gingival bleeding. The models revealed a strong genetic component behind the number of filled teeth, differing between males (49%) and females (68%), and a weaker genetic component affecting gingival bleeding, being similar for males and females (32%). Genetic factors contribute to inter-individual differences in oral health among young adults.

Tobacco use and reported bruxism in young adults: a nationwide Finnish Twin Cohort Study.

INTRODUCTION: Higher levels of smoking, leading to increased levels of nicotine and dopamine release, may be more strongly related to bruxism, although this relationship has remained unclear. Thus, the aim of the present study was to investigate the possible effect of cumulative tobacco use on bruxism in a large sample of young adults. METHODS: The material of the present study derives from the FinnTwin16, which consists of five birth cohorts born in 1975-1979. A total of 3,124 subjects (mean age 24 years, range 23-27 years) provided data in 2000-2002 on frequency of bruxism and tobacco use. Multinomial logistic regression was used to explore the relationships of frequency of bruxism with smoking and smokeless tobacco use while controlling covariates (alcohol intoxication, alcohol problems [Rutgers Alcohol Problem Index, RAPI], illicit drug use, psychological distress [General Health Questionnaire], and coffee use). RESULTS: Based on subjective response and multivariate analyses, weekly bruxers were more than two times more likely to report heavy smoking than never bruxers (odds ratio [OR] 2.5, 95 % CI 1.8-3.4). The significant association between heavy smoking and bruxism held when the effects of other tobacco use and multiple covariates were controlled. In addition, the use of smokeless tobacco emerged as an independent risk factor for bruxism. DISCUSSION: Given the observed associations with both heavy smoking and smokeless tobacco and a dose-response relationship, the present results support our hypothesis of a link between nicotine intake and bruxism.