Genome-wide association study of primary tooth eruption identifies pleiotropic loci associated with height and craniofacial distances.

Twin and family studies indicate that the timing of primary tooth eruption is highly heritable, with estimates typically exceeding 80%. To identify variants involved in primary tooth eruption, we performed a population-based genome-wide association study of 'age at first tooth' and 'number of teeth' using 5998 and 6609 individuals, respectively, from the Avon Longitudinal Study of Parents and Children (ALSPAC) and 5403 individuals from the 1966 Northern Finland Birth Cohort (NFBC1966). We tested 2 446 724 SNPs imputed in both studies. Analyses were controlled for the effect of gestational age, sex and age of measurement. Results from the two studies were combined using fixed effects inverse variance meta-analysis. We identified a total of 15 independent loci, with 10 loci reaching genome-wide significance (P < 5 × 10(-8)) for 'age at first tooth' and 11 loci for 'number of teeth'. Together, these associations explain 6.06% of the variation in 'age of first tooth' and 4.76% of the variation in 'number of teeth'. The identified loci included eight previously unidentified loci, some containing genes known to play a role in tooth and other developmental pathways, including an SNP in the protein-coding region of BMP4 (rs17563, P = 9.080 × 10(-17)). Three of these loci, containing the genes HMGA2, AJUBA and ADK, also showed evidence of association with craniofacial distances, particularly those indexing facial width. Our results suggest that the genome-wide association approach is a powerful strategy for detecting variants involved in tooth eruption, and potentially craniofacial growth and more generally organ development.

Orofacial pain and symptoms of temporomandibular disorders in Finnish and Thai populations.

OBJECTIVE: Cultural or ethnic factors may play an important role in subjects' pain reports. The aim of the study was to compare the prevalence of orofacial pain symptoms between Finnish and Thai populations. MATERIALS AND METHODS: The Finnish study population comprised the Northern Finland Birth Cohort 1966, of which 5696 subjects participated in the present study. The Thai sample consisted of 1501 randomly selected people living in 10 different districts in Bangkok. Data on orofacial pain was collected based on questionnaires. RESULTS: After adjusting for age, gender and education, the logistic regression analysis showed that Thai subjects had an increased risk for reporting oral pain (OR = 4.5, 95% CI = 3.7-5.4), tooth pain (OR = 2.0, 95% CI = 1.8-2.4) and pain in the face (OR = 1.5, 95% CI = 1.2-1.7). CONCLUSIONS: It can be concluded that Thai people report more orofacial pain symptoms than Finnish subjects. Cross-cultural factors exist in the background of reporting pain symptoms in the oral and facial area.

Association of smoking and snuffing with dental caries occurrence in a young male population in Finland: a cross-sectional study.

OBJECTIVE: The aim of this study was to investigate the prevalence of smoking and snuffing habits in association with dental caries occurrence in a male cohort born in the early 1990s in Finland. The impact of health behaviours and factors related to the place of residence were included in analyses. MATERIALS AND METHODS: Oral health of 8537 conscripts was screened in a cross-sectional study. In the same occasion they also answered a questionnaire covering their smoking and snuffing habits and other background factors. The residence-related factors were obtained from the Defence Forces' database. Cross-tabulation together with chi-squared test and generalized linear mixed models were used for analyses. RESULTS: Almost forty per cent (39.4%) of the men reported smoking daily and 9.0% reported daily snuffing. Restorative treatment need of those who reported frequent smoking was more than 2-fold (mean DT = 2.22) compared to the non-smokers (mean DT = 1.07). Smoking was statistically significantly associated with other harmful health behaviours. The snuffers reported more snacking than the non-smokers, but were most frequent brushers. The result from the statistical modelling showed that smoking, low tooth brushing frequency, eating sweets and consuming energy drinks frequently were significantly associated with restorative treatment need. CONCLUSION: In this cross-sectional study, association between smoking and dental caries was distinct. The high rate of restorative treatment need among smokers may be explained by their poor health behaviours. Dietary habits of the snuffers seem harmful too, but are compensated by good tooth brushing frequency.

Genome-wide association study reveals multiple loci associated with primary tooth development during infancy.

Tooth development is a highly heritable process which relates to other growth and developmental processes, and which interacts with the development of the entire craniofacial complex. Abnormalities of tooth development are common, with tooth agenesis being the most common developmental anomaly in humans. We performed a genome-wide association study of time to first tooth eruption and number of teeth at one year in 4,564 individuals from the 1966 Northern Finland Birth Cohort (NFBC1966) and 1,518 individuals from the Avon Longitudinal Study of Parents and Children (ALSPAC). We identified 5 loci at P<5x10(-8), and 5 with suggestive association (P<5x10(-6)). The loci included several genes with links to tooth and other organ development (KCNJ2, EDA, HOXB2, RAD51L1, IGF2BP1, HMGA2, MSRB3). Genes at four of the identified loci are implicated in the development of cancer. A variant within the HOXB gene cluster associated with occlusion defects requiring orthodontic treatment by age 31 years.

Prevalence and polarization of dental caries among young, healthy adults: Cross-sectional epidemiological study.

OBJECTIVE: Oral health of young people has improved in the industrialized countries during past decades. However, stagnation of this progress has been reported recently. The main aim of this epidemiological study was to investigate the level of cariological treatment history and need (DMFT, DT) and polarization of dental caries among a healthy young male population born in the early 1990s. MATERIALS AND METHODS: Oral health of 13,564 men and 255 women born in 1990, 1991 or 1992 was screened based on the WHO criteria for epidemiological studies by 15 calibrated dentists in 20 garrisons (of a total 24) of the Finnish Defence Forces in January and July 2011. Mean DMFT and DT (SD) values and their distribution were calculated excluding wisdom teeth. Polarization was investigated using the Lorentz analysis. RESULTS: Mean DMFT, DT and FT values were DMFT = 4.1 (SD = 4.2), DT = 1.4 (SD = 2.5) and FT = 2.7 (SD = 2.9). Almost half of the men (45.1%) and one third of the women (37.3%) had at least one tooth needing restorative treatment. About 30% of the conscripts had 90% of all caries lesions and ∼ 10% of the conscripts had half of all lesions. CONCLUSIONS: Oral health of young males has not improved since the previous study among conscripts 15 years ago. Polarization of dental caries still exists. About half of the young male population still has manifested dental caries. Oral health promotion must not be neglected, even in countries with low caries prevalence.

Self-reported gingivitis and tooth loss poorly predict C-reactive protein levels: a study among Finnish young adults.

OBJECTIVES: Our aim in this cross-sectional study was to investigate whether self-reported gingivitis and tooth loss were associated with elevated levels of C-reactive protein (CRP) using the same study population where these dental conditions have earlier been associated with prevalent angina pectoris. MATERIAL AND METHODS: The study population consisted of those Northern Finland birth cohort 1966 members who lived in Northern Finland or in the Helsinki region (n=8463) at the time of the survey (1996-1997). The participation rate in a health examination was 71% (n=6033). Gingivitis and tooth loss were determined on the basis of self-reported questions. Prevalence proportion ratios (PPR) and 95% confidence intervals (CI) were estimated using multivariate regression models. RESULTS: The results showed that self-reported gingivitis and tooth loss were weakly associated with elevated levels of CRP (>3 mg/l): adjusted PPR 1.1, CI 1.0-1.3 and PPR 1.1, CI 0.7-1.7, respectively. The proportion of variation in CRP explained by self-reported gingivitis and tooth loss was small, being <1%. CONCLUSION: The results suggest that self-reported gingivitis and tooth loss have a miniscule effect on CRP levels among a general population of young adults.

Dental check-ups in 31-year-olds in relation to optimism and life satisfaction.

OBJECTIVE: To analyse the impact of optimism and life satisfaction on dental check-ups. BASIC RESEARCH DESIGN: A cross-sectional study. PARTICIPANTS: The data used in this study consists of a postal questionnaire sent to the members of the 1966 Birth Cohort in Northern Finland. The number of replies totalled 8,690, giving a response rate of 75.3%. MAIN OUTCOME MEASURES: The subjects were classified into two categories according to frequency of dental check-ups: those who went for check-ups at least once in two years and those who went more rarely. A Life Orientation Test was used to measure optimism. Life satisfaction was measured using a single question. The other explanatory variables were gender, marital status, education, incomes and employment status. Multivariate analyses were performed using log-binomial regression models. RESULTS: Independent of other factors, life satisfaction among women and optimism among men was associated with dental check-ups. Links between socioeconomic factors and dental check-ups were weaker than anticipated. CONCLUSIONS: The results suggest that not only socioeconomic factors but also psychosocial aspects need to be taken into account in planning successful dental health policy.

Smoking, alcohol use, socioeconomic background and oral health among young Finnish adults.

OBJECTIVES: The aim of this study was to investigate the prevalence of smoking and alcohol use in association with dental caries experience and signs of periodontal disease in a Finnish male group born in the early 1990s. The impacts of health behaviour and socioeconomic factors were included in the analyses. METHODS: Oral health of 8539 conscripts was screened in a cross-sectional study (DT, DMFT and CPI). They also answered a questionnaire covering their habits of smoking and alcohol use as well as other behaviours and background factors. The bleeding on probing index (BOP) was available on 6529 conscripts. Cross-tabulation together with a chi-squared test and generalized linear mixed models were used in the analyses. A mosaic figure was used to illustrate associations of smoking frequency, use of dental services and toothache. RESULTS: Majority (80.9%) in the study group consumed alcohol at least once a month, and 39.4% were daily smokers. Smoking was statistically significantly associated with high caries experience and high bleeding values of gums. Consumption of alcohol was not associated with dental caries and periodontal disease. The high BOP value had the strongest association with infrequent tooth brushing and smoking. The participant's own education level was the main protective factor of oral health. The smokers used dental services more frequently compared to the non-smokers mostly for acute care. CONCLUSIONS: Young men's health behaviour, especially of those with low education, does not promote oral health, which may indicate need for extensive healthcare services in the future. Health promotion should not be neglected.

Should we brush twice a day? Determinants of dental health among young adults in Finland.

We explore the determinants of dental ill-health as measured by the occurrence of caries. A recursive bivariate probit model that was derived from health production and demand theory is employed to model caries, while taking account of dental care use. The data are from a follow-up questionnaire used in a longitudinal study of the Northern Finland 1966 Birth Cohort, with respondents aged 31 (n = 5020). The factors controlled for relate to family background and health behavior during their youth, current socioecononomic variables and dental health stock. The total effects on the occurrence of caries of the explanatory variables are computed. Among females, factors increasing caries are body mass index and intake of alcohol, sugar and soft drinks, and those reducing caries are birth weight and adolescent school achievement. Among males, caries is positively related to the metropolitan residence and negatively related to education and healthy diet. Smoking increases caries, whereas dental care use, regular dental attendance and brushing teeth at least twice a day decrease caries. To promote oral health, attention should focus on policies to improve dental health education and to reduce the impacts of common risk factors.

The relation of tobacco smoking to tooth loss among young adults.

Earlier studies have associated smoking with a higher rate of dental caries, periodontal disease and tooth loss. The aim of this cross-sectional study was to determine whether smoking is associated with tooth loss among young adults. The data consist of the 1966 birth cohort of Northern Finland, which is an unselected general population birth cohort (n = 12 058). The data were collected using a postal questionnaire in 1997-98 (n = 8690). Prevalence odds ratios and confidence intervals were estimated by applying a logistic regression model. It was found that smoking was associated with tooth loss in an exposure-dependent manner. The odds for those who smoked 16 or more pack-years were 5.30 (CI = 2.35-11.2) after adjustment for socio-economic and behavioral factors. Differences in socio-economic or health behavior are not likely to explain the findings since an exposure-response pattern was seen even when data was stratified according to sex, education and health-oriented lifestyle. A possible explanation for this association is a combination of treatment decisions and dental diseases, which are most likely associated with smoking in an exposure-dependent manner.