Interpreting Poisson Regression Models in Dental Caries Studies.

Oral epidemiology involves studying and investigating the distribution and determinants of dental-related diseases in a specified population group to inform decisions in the management of health problems. In oral epidemiology studies, the hypothesis is typically followed by a cogent study design and data collection. Appropriate statistical analysis is essential to demonstrate the scientific association between the independent factors and the target variable. Analysis also helps to develop and build a statistical model. Poisson regression and its extensions have gained more attention in caries epidemiology than other working models such as logistic regression. This review discusses the fundamental principles and basic knowledge of Poisson regression models. It also introduces the use of a robust variance estimator with a focus on the "robust" interpretation of the model. In addition, extensions of regression models, including the zero-inflated model, hurdle model, and negative binomial model, and their interpretation in caries studies are reviewed. Principles of model fitting, including goodness-of-fit measures, are also discussed. Clinicians and researchers should pay attention to the statistical context of the models used and interpret the models to improve the oral and general health of the communities in which they live.

Dental Erosion and Caries Status of Chinese University Students.

PURPOSE: To describe the prevalence and severity of dental erosion and caries experience of Chinese university students in Hong Kong. MATERIALS AND METHODS: First-year Chinese students were invited to attend a dental clinic at a university campus in Hong Kong during their freshman orientation. A questionnaire was used to investigate the potential factors affecting their dental status, including sociodemographic factors, toothbrushing habits, dietary habits (consumption of sugary drinks), time elapsed since last dental check-up and self-perceived dental erosion status. Three calibrated dentists performed the clinical examinations. Dental erosion was evaluated using the modified Basic Erosive Wear Examination (BEWE) and dental caries experience was measured using the DMFT index. RESULTS: In total, 600 participants aged 18-21 were examined and 44% showed some signs of dental erosion (maximum BEWE > 0). Severe dental erosion (BEWE = 3) was found in 1% of the adults. Many (69%) had caries experience (DMFT > 0); their mean DMFT score was 2.5 ± 2.7 (± SD). The total BEWE scores were found to be associated with age and self-perception of tooth misalignment. No correlation was found between BEWE score and dietary habits, oral hygiene practices or self-perceived dental erosion status. Females, those whose last dental check-up was more than a year ago and those who perceived having dental decay or tooth wear had higher caries experience. CONCLUSIONS: Nearly half of the Chinese Hong Kong university students had signs of dental erosion, but very few showed signs of severe erosion. Caries experience was widespread but not high.

Oral health status of elderly chinese with dementia in Hong Kong.

PURPOSE: To compare toothbrushing habits, unstimulated salivary flow rates and oral health status of elderly Hong Kong Chinese with and without dementia. MATERIALS AND METHODS: A sample size calculation was performed and a sample of 82 elderly Chinese with dementia were invited who were aged 60 or above, fit for periodontal assessment with probing and attended day-care centres. Age- and gender-matched generally healthy people without dementia were recruited as controls. Toothbrushing practices were recorded using a questionnaire. Additionally, unstimulated salivary flow rate was measured. Caries experience and periodontal status were assessed through clinical examination by the DMFT index and Community Periodontal Index (CPI), respectively. RESULTS: Fifty-nine people with dementia and 59 age- and gender-matched generally healthy controls were recruited. Their mean age was 80 (SD = 7). Compared with the individuals in the control group, fewer people with dementia performed toothbrushing twice daily (31% vs 5%; P < 0.001). Furthermore, their unstimulated salivary flow rate was lower than that of the control group (0.30 ml/min vs 0.41 ml/min; P = 0.043). Their caries experience in mean DMFT (± SD) was similar to the control group (22.3 ± 8.2 vs 21.5 ± 8.2, P = 0.59). There was also no significant difference in the prevalence of periodontal pockets (CPI  ≥ 3) between the two groups (78% vs 74%, P = 0.64). CONCLUSION: Compared to those without dementia, fewer elderly Chinese with dementia practiced toothbrushing twice daily. Although their resting salivary secretion was reduced, their caries experience and prevalence of advanced periodontal disease were not significantly different from those without dementia.