Caries risks and appropriate intervals between bitewing x-ray examinations in schoolchildren.

Short intervals between bitewing examinations favor the timely detection of lesions on approximal surfaces. Long intervals reduce the exposure to radiation. Thus, the question arises which intervals between bite-wing examinations are appropriate. The length of intervals between bitewing examinations should be adapted to the caries risk on approximal surfaces of molars and premolars. In order to estimate the caries risk in the Swiss school population, longitudinal data of 591 schoolchildren from the Canton (County) of Zurich were analyzed. These schoolchildren had been examined at 4-year intervals. The proportion of 7-year-olds with caries increment on approximal surfaces within 4 years was 7.1%, i.e., the caries risk in the population was 7.1%. In the 11-year-olds, the caries risk was 17.60%. Seven-year-olds without caries experience on selected approximal surfaces had a low caries risk of 2.2%. However, 7-year-olds with caries experience on selected approximal surfaces had a high risk of 24.2%. The same applied to 11-year-olds: those without caries experience had a low risk (7.5%), and those with caries experience had a high risk (38.5%). For the 7-year-old schoolchildren without any caries experience, an x-ray interval of 8 years is proposed. For the 7-year-old schoolchildren with caries experience, an x-ray interval of 1 year is proposed.

A program for computing the prediction probability and the related receiver operating characteristic graph.

Prediction probability (P(K)) and the area under the receiver operating characteristic curve (AUC) are statistical measures to assess the performance of anesthetic depth indicators, to more precisely quantify the correlation between observed anesthetic depth and corresponding values of a monitor or indicator. In contrast to many other statistical tests, they offer several advantages. First, P(K) and AUC are independent from scale units and assumptions on underlying distributions. Second, the calculation can be performed without any knowledge about particular indicator threshold values, which makes the test more independent from specific test data. Third, recent approaches using resampling methods allow a reliable comparison of P(K) or AUC of different indicators of anesthetic depth. Furthermore, both tests allow simple interpretation, whereby results between 0 and 1 are related to the probability, how good an indicator separates the observed levels of anesthesia. For these reasons, P(K) and AUC have become popular in medical decision making. P(K) is intended for polytomous patient states (i.e., >2 anesthetic levels) and can be considered as a generalization of the AUC, which was basically introduced to assess a predictor of dichotomous classes (e.g., consciousness and unconsciousness in anesthesia). Dichotomous paradigms provide equal values of P(K) and AUC test statistics. In the present investigation, we introduce a user-friendly computer program for computing P(K) and estimating reliable bootstrap confidence intervals. It is designed for multiple comparisons of the performance of depth of anesthesia indicators. Additionally, for dichotomous classes, the program plots the receiver operating characteristic graph completing information obtained from P(K) or AUC, respectively. In clinical investigations, both measures are applied for indicator assessment, where ambiguous usage and interpretation may be a consequence. Therefore, a summary of the concepts of P(K) and AUC including brief and easily understandable proof of their equality is presented in the text. The exposure introduces readers to the algorithms of the provided computer program and is intended to make standardized performance tests of depth of anesthesia indicators available to medical researchers.

Further caries decline in Swiss recruits from 1996 to 2006.

Previous investigations showed a steady decline of the caries experience. The purpose of this study was to determine the caries experience of Swiss recruits in 2006 and to compare it to that of 1985 and 1996. The results of a parallel investigation which dealt with the periodontal health of the same recruits have already been published (Röthlisberger et al. 2007). Investigations on recruits in 1970 (Curilovic et al. 1972) and 1974 (Curilovic et al. 1980) used another methodology. Therefore, they were not included here for comparison.

Assessment of dental fluorosis prevalence in Swiss populations.

In 1996 and 2006, recruits of the Swiss army participated in a dental survey. Similarly in 1995/96 and 2004/05, randomly selected schoolchildren from 16 rural communities of the Canton of Zurich participated in a dental survey. As part of these surveys, color slides were taken of the incisor teeth of all recruits, as well as of third and fourth grade schoolchildren. The slides (N = 2049) were examined for the presence of fluoride-associated enamel opacities (FOP), using the Thyl-strup-Fejerskov (TF) index. Two examiners (A and B) assessed all slides. The examiners were blind as to the year of survey. Examiner A recorded prevalences of FOP between 18% and 27% depending on population; examiner B recorded prevalences between 7% and 12%. The examiners' influence on the estimation of the prevalence was obvious. The prevalences reported should, therefore, be considered as rough estimates. FOP of TF score 2 were only observed in approximately 1% of the participants. One examiner recorded a TF score 3 in a single individual. FOP therefore are not a cosmetic problem and certainly not a public health concern. The prevalence of FOP decreased slightly during observation period I (recruits born 1975-77 vs 1985-87) and period II (school children born 1985-87 vs 1994-96). However, the decline was statistically supported in only one instance (Period I, Examiner B).

Changes in dental caries in Zurich school-children over a period of 45 years.

In 16 rural communities of the Canton of Zurich, school-children of all age groups participated in dental examinations conducted at intervals of 4 years since 1963/64. The same standardised method was used throughout the entire period. This study documents the caries experience over a period of 45 years. From 1964 to 2009, the DM*FT per 14-year-old child fell from 12.50 to 1.31, corresponding to a caries reduction of 90%. The caries experience in 8-, 10- and 12-year-olds decreased by 90% to 92%. From 1964 to 2009, the "Significant Caries Index" (the mean DM*FT in the third of 12-year-olds with the highest DM*FT values) fell from 13.09 to 2.20, corresponding to a caries reduction of 83%. The observed caries decline was unexpectedly high. The effect of fluorides may explain a caries reduction of roughly 50%. A large part of the decline, however, remains unexplained. Possible causes are discussed in this paper.

[Early childhood caries--facts and prevention]. / Kleinkinderkaries--Fakten und Vorbeugung.

In 2003, 771 randomly selected two-year-old children from the town of Zurich were examined. Teeth with carious cavities were observed in 12.6% of the children. Caries including initial (not yet cavitated) lesions was seen in 25.3% of children. Caries prevalence was strongly associated with immigrant background. Caries was found in 7.5% of Swiss children and in 38.5% of children from ex-Jugoslavia. 5% of children of mothers born in Switzerland, and 17.4% of children of mothers not born in Switzerland showed caries. The average number of teeth with carious lesions in children with caries was 4.3 irrespective of immigrant or Swiss background. This finding suggests that all kids with caries had similar risk behaviours. Multivariate logistic regressions elucidated the behavioural components associated with caries. The presence of plaque and the use of a night-time bottle proved to be the strongest predictor variables for caries. Frequent drinking of sugared non-milk drinks, age and no pacifier use were further risk indicators in children of foreign-born mothers. A significant improvement of oral health of small children can be achieved by a concerted action of child welfare consultants, paediatricians and carers of day-nurseries. The primary goal is to convince parents to actively participate in preserving dental health of their offsprings. The following recommendations should be adhered to: 1. Parents should brush the teeth of the children daily, using a fluoridated children-toothpaste starting the very day of the appearance of the first milk tooth. 2. At the age of 12 months, the bottle should be replaced by a cup and the continuous use of a nursing bottle while falling asleep and during the night should absolutely be avoided. 3. Children should primarily be offered water and milk as a beverage. A first dental inspection is due at the age of two years.

Use of the Significant Caries Index in quantifying the changes in caries in Switzerland from 1964 to 2000.

OBJECTIVES: To follow the changes in the Significant Caries Index (SiC) and the DMFT during the period 1964-2000 in children aged 12 and 15 in the Canton of Zurich. METHODS: Examinations of random samples of children in 16 communities of the Canton were repeated every 4 years from 1964 onwards using the same standards for diagnosing caries. RESULTS: In the 12-year-olds, the children in the low tertile had virtually no DMF-experience from 1980 on. On the contrary, the SiC, based on the children in the highest tertile, decreased until 1996. At the age of 15, the zero-average in the low tertile was reached in 1992 but the SiC continued to decrease until 2000. In the 12-year age group the reduction of the SiC from 1964 to 1996 was 81.3% and for the overall DMFT it was 89.7%. The corresponding reductions for the 15-year-olds, in this case from 1964 to 2000, were 77.0 and 88.4%, respectively. The DMFT-counts in the total samples had substantially higher coefficients of variation than those in the highest tertile. As a consequence, the SiC had relatively smaller confidence intervals than the average DMFT. CONCLUSIONS: The SiC is a very useful measure of dental caries experience. On the basis of the results in the 15-year-old group, the target of an SiC below 5.0 is proposed. The decline of the SiC demonstrates that even in the high-risk children caries experience has been reduced substantially.

Effect of 1000 ppm relative to 250 ppm fluoride toothpaste. A meta-analysis.

PURPOSE: To estimate the overall effect of 1000 ppm F relative to 250 ppm F toothpaste. METHODS: Experimental caries increment studies from the dental literature, which compared 1000 ppm with 250 ppm fluoride toothpastes, were summarized using meta-analytic methods. RESULTS: The overall caries reduction of 1000 ppm F relative to 250 ppm F paste was estimated to be 0.142 (95%-CL: 0.074-0.210) when applying a fixed effects model and 0.129 (95%-CL: 0.012-0.230) when applying a random effects model. CLINICAL SIGNIFICANCE: The present analysis found slightly lower caries increments (14%, 13%) in children using 1000 ppm F toothpastes compared to children using 250 ppm F pastes. On the other hand, the use of 1000 ppm F pastes is associated with dental fluorosis. Considering these effects it seems justifiable to the authors to keep the use of 250 ppm F pastes for preschool children in Switzerland.

[Caries prevalence among students in the city of Winterthur: comparison with the city of Zurich and 16 communities in the canton of Zurich]. / Kariesprävalenz von Schülern der Stadt Winterthur: Vergleiche mit der Stadt Zürich und 16 Zürcher Landgemeinden.

The aim of the present survey was to assess the caries prevalence in schoolchildren of the city of Winterthur in the year 2002. A simple random sample of 1000 schoolchildren was drawn. 65% of the children participated in the standardized investigation. The mean DMFT-value (permanent dentition) in 12-year-olds was 1.0 and was on a low level in a European comparison. The mean dmft-value (deciduous dentition) in 7-year-olds was 2.0. From 1971 to 2002, DMFT-values decreased by about 80% in Winterthur. The dmft-values decreased by about 60%. The splitting by nationality revealed a high caries prevalence in schoolchildren from the former Yugoslavia and Albania. A multivariate analysis showed no significant differences in caries prevalence between the schoolchildren of the city of Winterthur and other communities of the canton of Zurich.

[Caries prevalence among 5-year-olds in the city of Winterthur in the year 2001]. / Kariesprävalenz von 5-Jährigen der Stadt Winterthur im Jahre 2001.

The aim of the present study was to assess the caries prevalence of 5-year-olds in the city of Winterthur in 2001. By simple random sampling 350 children were selected. Two-hundred-and-ninety-one of the children (83%) participated. The mean dmft-value was 2.42; of that 1.87 were untreated carious teeth (dt). Forty-five per cent of the children showed caries in the deciduous dentition. Twenty-one per cent of the children had high caries experience (5 or more dmft). Twenty-one per cent showed caries in deciduous incisors. In 4% of the children primary molars were missing. Splitting by nationality revealed great differences. On average, the Swiss children had 1.70 dmf-teeth; the ex-Yugoslavian and Albanian children had 7.84 dmf-teeth. Fifteen percent of the Swiss children had high caries experience; in contrast 65% of the ex-Yugoslavian and Albanian children had high caries experience.

[Caries prevalence among students in 16 Zurich districts in the years 1992 to 2000]. / Kariesprävalenz von Schülern in 16 Zürcher Landgemeinden in den Jahren 1992 bis 2000.

Standardized dental examinations of schoolchildren were regularly carried out since 1964 in 16 rural communities of the Canton of Zurich. In 1964, there were no 14-year-old schoolchildren free from caries; in the Nineties about half of the 14-year-olds had a caries-free permanent dentition (DMFT = 0). From the year 1992 to 2000, the caries prevalence (DMFT) of 14-year-olds decreased once again, by 31%. The pit and fissure caries prevalence (DFS) of 12- and 14-year-olds decreased by 28% and 37%, respectively. In 2000, the mean DMFT-value of the 12- and 14-year-old schoolchildren was 0.90 and 1.27 respectively. In 1964, only few 7-year-old schoolchildren were caries-free; in the Nineties about half of the 7-year-olds had a primary dentition without caries. From the year 1992 to 2000, caries prevalence (dmft) in 7-, 8- and 9-year-olds increased by 64%, 22% and 31%. In 2000, the mean dmft-value of all 7-year-old schoolchildren was 2.45. The Swiss schoolchildren had 1.79 dmft; the schoolchildren from former Yugoslavia and from Albania had 6.89 dmft and those of other nations had 3.37 dmft. Possible reasons for the continuous caries decrease in the permanent dentition and the increase in the primary dentition are discussed. Additional measures in order to improve the situation in the primary dentition are proposed.

An example of complex modelling in dentistry using Markov chain Monte Carlo (MCMC) simulation.

BACKGROUND: In the usual regression setting one regression line is computed for a whole data set. In a more complex situation, each person may be observed for example at several points in time and thus a regression line might be calculated for each person. Additional complexities, such as various forms of errors in covariables may make a straightforward statistical evaluation difficult or even impossible. OBJECTIVE AND METHOD: During recent years methods have been developed allowing convenient analysis of problems where the data and the corresponding models show these and many other forms of complexity. The methodology makes use of a Bayesian approach and Markov chain Monte Carlo (MCMC) simulations. The methods allow the construction of increasingly elaborate models by building them up from local sub-models. The essential structure of the models can be represented visually by directed acyclic graphs (DAG). This attractive property allows communication and discussion of the essential structure and the substantial meaning of a complex model without needing algebra. EXAMPLE: After presentation of the statistical methods an example from dentistry is presented in order to demonstrate their application and use. The dataset of the example had a complex structure; each of a set of children was followed up over several years. The number of new fillings in permanent teeth had been recorded at several ages. The dependent variables were markedly different from the normal distribution and could not be transformed to normality. In addition, explanatory variables were assumed to be measured with different forms of error. Illustration of how the corresponding models can be estimated conveniently via MCMC simulation, in particular, 'Gibbs sampling', using the freely available software BUGS is presented. In addition, how the measurement error may influence the estimates of the corresponding coefficients is explored. It is demonstrated that the effect of the independent variable on the dependent variable may be markedly underestimated if the measurement error is not taken into account ('regression dilution bias'). CONCLUSION: Markov chain Monte Carlo methods may be of great value to dentists in allowing analysis of data sets which exhibit a wide range of different forms of complexity.

[Dental health of adults in the Zurich Canton]. / Zahngesundheit von Erwachsenen im Kanton Zürich.

In 1992 and 1999, dental health in 20- to 79-year-old adults from the canton of Zurich was assessed with a standardized method (WHO). The aim was to establish the current state and changes of dental health. Roughly half of the 852 approached adults selected by chance did take part. In 1992 and 1999, the mean number of unfilled, decayed teeth (DT) was on a low level in all age classes (0.2 to 1.8 depending on age class and examination year). The number of missing teeth (MT) in older adults (60-79) was on a high level (8.8 to 13.4). The number of filled teeth (FT) was highest (14.8 to 16.2) in middle-aged adults (40-59). Total loss of teeth was found only in older adults (60-79). Lack of a "functional" own dentition (5 teeth present in each quadrant) was found in roughly half of the 60- to 69-year-olds and two thirds of the 70- to 79-year-olds. In 1999, the state of the roots and loss of attachment was assessed. Wedge-shaped defects were found in more than half of the middle-aged adults (40-59). Carious roots were found in more than half of the 70- to 79-year-olds. Nearly half of the 70- to 79-year-old participants showed "severe" loss of attachment (> or = 6 mm). In the short period from 1992 to 1999, a significant decrease of 3.7 DMFT was found in 20- to 49-year-old adults. The decrease of 0.9 MT and 2.1 FT means also a decrease in treatment need in this age segment. In contrast, in the 50- to 79-year-olds no change in dental health could be established.