Dentist-specific variation in diagnosis of caries - a multilevel analysis.

BACKGROUND: There are few studies on practice variation within dentistry. This contrasts with medicine where numerous studies exist. A major finding from the field of medicine is that the size of the physician-specific effects depends on the degree of uncertainty in diagnosis. The physician-specific effects are small for diseases where the diagnostic criteria are unambiguous. Conversely, the effects are large for diseases where the diagnostic criteria are less unambiguous. OBJECTIVES: To assess the size of provider-specific variation in the diagnosis of caries among children and adolescents in Norway and to determine whether this variation depends on uncertainty in diagnosis. METHODS: Data on caries diagnosis for 709 611 children and adolescents aged 6-18 years were analysed using multilevel regression. Level-1 was patients and level-2 was public dental officers and dental hygienists. Caries was measured according to the following localization of the lesion: in the outer half of the enamel, in the inner half of the enamel, in the outer third of the dentine, in the middle and inner third of the dentine, to the pulp. The degree of uncertainty in diagnosis is expected to be least the deeper into the dentine the lesion goes. Our sample included 87.5% of all individuals aged 6-18 years. RESULTS: The provider-specific variation, measured as the intraclass correlation coefficient, ranged from 15% for caries lesions localized in the outer half of the enamel to 2% for caries to the pulp. CONCLUSIONS: The size of provider-specific variation in the diagnosis of caries is fairly low. The size of the variability is dependent on the level of diagnostic uncertainty, which is coherent with the practice style hypothesis.

Per capita remuneration of dentists and the quality of dental services.

OBJECTIVES: The aim of this study was to examine the effects of a per capita based remuneration system on the quality of dental care. METHODS: The basis for the study was a natural experiment in the county of Østfold in Norway in which all public dental officers (n = 34) were given the opportunity to renegotiate their contract from a fixed salary to a combined per capita and fixed salary contract. Quality was assessed according to three criteria: number of preventive procedures, number of under-diagnosed carious lesions and number of untreated carious lesions. This information was selected from a random sample of patient records for 18-year-olds in the autumn of 1999 (base-line data) and at the end of 2006 (final data), altogether 20 records per dentist. At the end of the period of evaluation, 26 dentists were still eligible for inclusion in the study. The data were analysed both descriptively and using multilevel difference-in-difference regression models. RESULTS: The main finding was that the transition to a per capita remuneration system did not lead to under-diagnosis of carious lesions, under-treatment or less prevention. CONCLUSIONS: A per capita remuneration scheme did not lead to a fall in the quality of dental care. This result must be assessed taking into account that the experiment was carried out within a publicly financed and managed dental service. Also, the incentive effect of the per capita contract was relatively weak.

Perspectives on providing good access to dental services for elderly people: patient selection, dentists' responsibility and budget management.

OBJECTIVES: To suggest a model for organizing and financing dental services for elderly people so that they have good access to services. BACKGROUND: There are few studies on how dental services for elderly people should be organized and financed. This is surprising if we take into consideration the fact that the proportion of elderly people is growing faster than any other group in the population, and that elderly people have more dental diseases and poorer access to dental services than the rest of the adult population. In several countries, dental services are characterized by private providers who often operate in a market with competition and free price-setting. Private dentists have no community responsibility, and they are free to choose which patients they treat. MATERIAL AND METHODS: Literature review and critical reasoning. RESULTS: In order to avoid patient selection, a patient list system for elderly people is recommended, with per capita remuneration for the patients that the dentist is given responsibility for. The patient list system means that the dentist assumes responsibility for a well-defined list of elderly people. CONCLUSION: Our model will lead to greater security in the dentist/patient relationship, and patients with great treatment needs will be ensured access to dental services.

Socioeconomic inequalities in dental services utilisation in a Norwegian county: the third Nord-Trondelag Health Survey.

AIM: To assess the level of socioeconomic inequity in dental care utilisation in Norway and enable comparison with recent international comparative studies. METHODS: We studied dental care utilisation among 17,136 men and 21,414 women in the third Nord-Trøndelag Health Survey (2006-08). Respondents aged 20 years and above were included in the study, and analyses were also performed within subgroups of age and gender (20-39, 40-59, and ≥60 years). Income-related horizontal inequity was estimated by means of concentration indices. Education-related inequity was estimated as relative risks. RESULTS: We found consistent pro-rich income inequity among men and women of all ages. The level of income inequity was highest among men and women ≥60 years, and in this group the income gradient was steepest between the poorest and the middle quintiles. Pro-educated inequity was found exclusively among men and women ≥60 years. General attendance was high (77%). CONCLUSION: The overall level of income-related inequity in dental services utilisation was low compared to other European countries as reported in two recent international studies of socioeconomic inequalities in dental care utilisation. Pro-rich and pro-educated inequity is a public health challenge mainly in the older part of the population.

Occurrence of risk factors for dental erosion in the population of young adults in Norway.

OBJECTIVES: The aim of this study was to describe the occurrence of risk factors for dental erosion for a group of young adults who are particularly susceptible to erosion. Another aim was to describe the awareness of erosion and distribution of risk factors according to the educational background of the parents. METHODS: The sample (n = 2004 individuals) was randomly drawn from the population of 19-20-year-old Norwegians. The data were collected using telephone interviews. We measured awareness about erosion using the following question: 'Have you ever heard about dental erosion?' We obtained information about the frequency of intake of the following risk factors: soft drinks with and without sugar, and juice. Soft drinks with sugar included lemonade (Coca-Cola, Solo, Pepsi, Mozell and ice tea) and sport drinks (XL1, Maxim). Soft drinks without sugar included Cola light, Zero, PepsiMax, Solo light and ice tea light. Juice included orange, grapefruit, apple and kiwi juice. The parents' level of education was based on the Norwegian school system, which has three levels: compulsory schooling (10 years), upper secondary school education (up to 13 years) and university/college education. The data were analysed using logistic regressions analyses. RESULTS: Awareness of erosion was high - 93.5% of respondents were aware of the problem. The majority of respondents believed that erosion can be prevented - altogether 84.9%. They also believed that soft drinks with and without sugar are equally important for the development of erosion. 17.5% of respondents drank soft drinks with sugar daily or several times a day. The corresponding figures for soft drinks without sugar and juice were 4.9% and 34.1%, respectively. Young adults with mothers with high education drank soft drinks both with and without sugar less frequently than those who had mothers with low education. This pattern was the opposite for juice. CONCLUSION: Consumption of soft drinks and juice is high, even though awareness and knowledge about the causes of erosion are widespread. This indicates the need for effective intervention strategies to reduce the level of consumption. These strategies should take into account the fact that the distribution of risk factors is skewed with respect to parents' level of education.

Demand for and utilization of dental services according to household income in the adult population in Norway.

OBJECTIVES: The aim of this study was to describe the effect of income on demand and utilization of dental services according to household income in the adult population. METHODS: The data were collected using a questionnaire, which was sent to a random sample of Norwegians aged 20 years or older living at home, 1861 persons in total. Demand was measured according to whether the person had been to the dentist during the last year. Utilization was measured as expenditure for dental treatment for those who had been to the dentist during the last year. The independent variables were the respondents' household income, age, gender, education, dental status and the mean fee for a dental consultation in the municipality. In the first stage, we carried out a logistic regression analysis of the log odds of having demanded dental services during the last year. In the second stage, we carried out a multiple regression analysis of expenditure for dental treatment for those who had been to the dentist during the last year. RESULTS: Altogether, 80% of the respondents had been to the dentist during the last year. Demand during the last year varied most according to dental status. There was little difference between men and women. The results of the logistic regression showed that the probability of having been to the dentist was 0.82 for those with a household income of €25 000 and 0.85 for those with a household income of €100 000. Mean expenditure for dental treatment was €355. There was no statistically significant relationship between household income and expenditure for dental treatment. CONCLUSIONS: Differences in demand for dental services according to household income are small, and there are no differences in utilization according to income. The findings are interesting, because in a population in which people have to pay almost all the costs for dental treatment themselves, one would expect the income differences in demand and utilization to be greater.

Equality in adults' oral health in Norway. Cohort and cross-sectional results over 33 years.

OBJECTIVE: To assess social inequality in dental clinical parameters from 1973 to 2006. METHODS: Samples from two birth-cohorts born between 1929-1938 and 1959-1960, respectively, and 35-44-year-olds were drawn in 1973, 1983, 1994 and in 2006 in the county of Nord-Trøndelag in Norway. Standard procedures were followed all the time. The examination comprised caries and caries treatment experience by DMF criteria and a questionnaire. Length of education in years was divided into quartiles in 1983, 1994 and 2006 to analyse the association between social status and clinical parameters. Statistical analyses were conducted within the same study year and between the years 1983 and 2006 by descriptive statistics and anova. RESULTS: The study showed that the DMFT/S index increased in the two birth-cohorts from 1973 to 1983 where after fewer changes occurred. However, there was a great improvement in oral health among 35-44-year old during the period from 1973 to 2006. The inequalities observed in 1983 remained or decreased and there was equality in number of present teeth all the time. The DMF results from the birth-cohorts showed that if social differences appear at an early age, they will persist in the cohorts the next 30 years and more. This is mainly because of the irreversibility of the DMF registrations. CONCLUSIONS: Social inequality was reduced but found in some indicators of dental status in 2006. Part of it can be explained by the insensitivity of the applied indexes. There is still a social divide in oral health and it affects elderly more than younger adults.

Dental caries risk studies revisited: causal approaches needed for future inquiries.

Prediction of high-risk individuals and the multi-risk approach are common inquiries in caries risk epidemiology. These studies prepared the ground for future studies; specific hypotheses about causal patterns can now be formulated and tested applying advanced statistical methods designed for causal studies, such as structural equation modeling, path analysis and multilevel modeling. Causal studies should employ measurements, analyses and interpretation of findings, which are in accordance to causal aims. Examples of causal empirical studies from medical and oral research are presented.

Incentives and remuneration systems in dental services.

The aim of this study was to examine the effects of an incentive-based remuneration system on number of individuals under supervision and on quality of public dental services in Norway. The basis for the study was a natural experiment in which all public dental officers in one county were given the opportunity to renegotiate their contract from a fixed salary contract to a combined per capita and fixed salary contract. Comprehensive data were collected before and after the change. A main finding is that the transition to an incentive-based remuneration system led to an increase in the number of individuals under supervision without either a fall in quality or a patient selection effect.

Caries and restoration prevention.

BACKGROUND: The authors analyzed studies of decayed, missing and filled (DMF) rates for surfaces and teeth in Norway published during the last 30 years. The result of active fluoride therapy combined with a change in criteria for when to place restorations led to a marked reduction in the need for restorations. METHODS: The authors reviewed independent, cross-sectional DMF studies of representative samples of young adults performed every 10 years during the period 1973 through 2006. The clinicians involved in the studies used standardized and calibrated methods. The authors of this article also reviewed an additional series of studies collecting DMF data from representative samples of 15-year-old adolescents that also had been carried out independently from 1979 through 1996. In these studies, the investigators examined clinical records and bitewing radiographs with attention to progression of carious lesions and restorative treatments. RESULTS: The authors noted a marked reduction in the mean decayed, missing and filled surface (DMFS) scores from 1973 through 2006 in the two adult groups. They also found a significant decrease in treatment of caries. The reduction was most marked after the mid-1990s. They noted that the most dramatic change in the data from the 15-year-olds resulted from a change in the treatment criteria during the 1980s. Approximal lesions in enamel were monitored by the investigators of those studies in combination with the use of fluoride toothpaste. CONCLUSION AND CLINICAL IMPLICATIONS: A caries treatment approach based on active caries-preventive treatment and restrictive criteria for restoration placement are good bases for reducing the need for restorations as shown in cross-sectional studies reviewed.

Oral health equality during 30 years in Norway.

OBJECTIVES: To study the relationship between income and edentulousness and having a functional dentition from 1975 to 2002, and to examine whether or not the findings can be characterized as a social gradient. METHODS: Four datasets were collected by personal interviews and precoded questionnaires by Statistics Norway in 1975, 1985, 1995 and 2002. The datasets were representative of the non-institutionalized adult population in Norway. Each year, the sampled persons were distributed into five income quintiles. Four effects were examined of the relationship between income quintiles and edentulousness and functional dentition (1) the absolute equality effect, (2) the period effect, (3) the relative equality effect, and (4) the gradient effect. RESULTS: The main finding is that in absolute terms oral health is more equally distributed in 2002 than in 1975, and the lowest income groups benefited the most in oral health. Among the elderly, however, having a functional dentition was less equally distributed in 2002. The relative differences increased for the oldest for each new birth cohort; thus, the chances of being edentulous was 7.5 times higher in the lowest income group versus the highest group in 2002, whereas the chances were only two times higher in 1972. Having lost all natural teeth was infrequent in 2002, and inequality wiped out in the population below > or = 60 years. A small social gradient was still in 2002. CONCLUSIONS: The condition of edentulousness is a result of accumulated incidences of dental diseases and fragmented access to dental care. Economic barriers and unavailability of dental care postponed necessary restorative dental care and resulted in more drastic treatment solutions previously especially in the rural areas in Norway.

The relationship between prevalence and incidence of dental caries. Some observational consequences.

To investigate the relationship between incidence and prevalence of caries. The principles are illustrated by means of Lexis diagrams, which show the relationship between cases of caries belonging to a population with a certain incidence and natural course of the disease in time. The analysis shows how studies on prevalence yield associations that reflect the determinants of the disease progression just as much as the causes of disease. Also the diagnostic criteria of the disease affect the prevalence estimate. The presence of fluoride changes the course of the disease and the prevalence estimate even with an unchanged incidence rate. This knowledge about incidence and prevalence should be taken into consideration when data from cross-sectional and time-series studies are interpreted. In an example from Norway the prevalence of caries was reduced. During the same period fluoride was made universally available, invasive treatment criteria were changed to less invasive and the time between the regular examinations were extended. These factors affect the estimates of caries made by cross-sectional recordings.

Causes and prevention of dental caries: a perspective on cases and incidence.

PURPOSE: The purpose of the present paper is: 1) to review recent concepts of the causes of caries; 2) to illustrate parameters of causes of cases and of incidence; and 3) to outline the consequences for caries prevention and oral health promotion. The paper is divided in three sections. Section 1 reviews recent theories of the causes of caries and summarizes that it is necessary to make a clear distinction between the causes of a case of caries and causes of occurrence of caries in populations. Cases relate to the reasons why individuals get sick, while incidence relates to why so many (or so few) within a population get sick. In section 2 the difference between the causes of a case and of the occurrence in a population is illustrated. A new social epidemiology moves beyond the focus on individual level risk factors to a multi-level perspective. Applied to oral diseases the paradigm of social epidemiology bridges our understanding of the biological determinants of caries with an understanding of the societal determinants of caries. Social epidemiology is the branch of epidemiology that studies the social distribution and social determinants of states of health. Individuals are embedded in societies and populations. In section 3 the insight acquired above is applied to the choice of disease-preventive and oral health-promotive strategies. Prevention of caries and promotion of oral health must be rooted in the understanding of caries as it occurs in populations.

Factors influencing the caries decline in Lithuanian adolescents--trends in the period 1993-2001.

The study aimed to relate a number of factors to the numbers of decayed, missing and filled teeth (DMFT) in 12- and 15-yr-olds examined and interviewed in 1993 and 2001. A total of 1250 children in 1993 and 935 in 2001 were clinically examined and completed a detailed questionnaire on dental health-related topics. Factors were related to the DMFT count applying multiple regression analysis. From 1993 to 2001, the mean DMFT decreased approximately 30% in both age cohorts. Despite an observed improvement in dental health in Lithuanian children, the number of Lithuanian children reporting frequent sugar consumption, brushing teeth irregularly and visiting the dentist only in case of emergency was still high compared with Western countries. The DMFT values were related to the fluoride content in the drinking water, oral hygiene, residency and year of examination.

Changes in restorative caries treatment in 15-year-olds in Oslo, Norway, 1979-1996.

OBJECTIVES: To examine changing patterns regarding restorative treatment criteria for dental caries. METHODS: A representative sample (n = 215) was drawn from all 15-year-olds receiving dental treatment in the Public Dental Service (PDS) in Oslo, Norway for each of the years 1979, 1989, 1993 and 1996. Information from clinical records and bitewing radiographs on caries treatment was collected. The results presented in this paper pertain to 198, 201, 209 and 208 subjects in each group. RESULTS: The results revealed dramatic changes in the use of restorative treatment criteria. Only 16% of tooth surfaces were treated in 1996 according to the criteria from 1979. The number of sound surfaces was found to have increased by 39% whereas the number of filled surfaces was reduced by 92%. In spite of more stringent criteria for restorative treatment, the number of D4 lesions did not increase. CONCLUSION: The practice of change in restorative treatment continued during the 17 years of study. Though the number of decayed surfaces appeared to be stable during the period, in reality, there was a reduction in caries occurrence during the first 10-year period (1979-1989). A conceptual model of dentists' caries-related treatment decisions outlined by Bader & Shugars may be used to explain parts of the rapid change in the criteria used in the PDS in Oslo.

Are there differences in oral health and oral health behavior between individuals with high and low dental fear?

Epidemiological studies of the relationship between dental fear, use of dental services, and oral health in different age groups in a common population are scarce. Dental fear and its relationships are usually described in individuals with high dental fear only. The purposes of this study were to describe the prevalence of dental fear in the Norwegian adult population according to age, and to explore differences in oral health, oral hygiene, and visiting habits between individuals with high and low dental fear. For the present study, data from the Trøndelag-94 study were used. The prevalence of dental fear in our study population of adults in Trøndelag, Norway was 6.6%. There was a tendency for individuals with high dental fear to engage in avoidance behavior more frequently than the low dental fear group. Individuals with high dental fear had a statistically significantly higher number of decayed surfaces (DS), decayed teeth, (DT) and missing teeth (MT) but a statistically significantly lower number of filled surfaces (FS), filled teeth (FT), functional surfaces (FSS), and functional teeth (FST). There were no differences in DMFS and DMFT between the groups of high and low dental fear. Since one of the superior aims of the dental profession is to help a patient to achieve a high number of functional teeth throughout life, consequently detecting and treating dental fear should therefore be an important aspect of dental processionals' work.

Do young adults demand more dental services as their income increases?

Several studies from the USA have shown that there is a positive and strong relationship between income and demand for dental care. All these studies have been performed on populations where treatment needs were high. Today, young adults represent one group of the population where treatment needs are low. But young adults will not necessarily demand or utilize more dental services as their income increases. As we do not know the extent to which demand will increase when income increases among young adults, future needs for dental manpower could be less than predicted from previous studies. The aim of the present study was to examine the relationship between income and demand/utilization for dental services among young adults in Norway. The analyses were performed on two large sets of survey data, collected in 1985 and 1995, which were representative of the Norwegian population aged 20 years and above. The main finding was that the increase in demand with an increase in income was less for young adults than for older adults. In particular, there was a marked fall in the income elasticities among young adults from 1985 to 1995. The fall in the income elasticity corresponds to a marked decrease in the prevalence of dental diseases among young adults during that period. Our results imply that future policies for dental manpower should take into account the lower income elasticity for young adults compared to for older adults, and that future needs for dental personnel should be planned accordingly.

Dental health patterns in young adults in Lithuania: an exploratory, analytical approach.

Patterns of variation in experience related to caries and treatment with regard to psychosocial, socio-economic, lifestyle, and oral healthcare-related characteristics were explored. A random sample of 382 (response rate 51%) subjects residing in 10 areas of Lithuania was examined (35 to 44-year-olds). Participants were given a dental examination and asked to complete a structured questionnaire. Experience related to caries and treatment differed with regard to residency and between genders. Analysis of self-reported data elucidated different aspects of psychosocial and socio-economic status and a variety of lifestyle factors. Interrelationships between the studied determinants were also analysed. Different patterns of dental health were revealed for men and women and for urban and rural participants. It can be concluded that factors influencing the dental status of Lithuanians are not only multiple, they seem also to influence dental health in complex ways. An exploratory approach should therefore be considered as a prerequisite to a causal approach of studying caries in populations.

Validity of a questionnaire survey: response patterns in different subgroups and the effect of social desirability.

Questionnaire surveys are often used in epidemiology and survey research. However, investigations have shown that the method suffers from biases. If the intention is to examine differences between subgroups in a sample, studies have shown that people tend to give answers to questionnaires more according to a social norm than to the actual situation. This has been called social desirability. The aim of this study was to investigate response bias in subgroups of a sample in a large questionnaire survey (n = 9,200) and to study whether social desirability has an impact on survey results in dental research. The answers were divided into subgroups according to gender, age, and residence and were compared with corresponding data from dental insurance claims. The levels of agreement were found to vary considerably and the differences were highly statistically significant. The variation in agreement showed that bias on the group level increased when the distance from an anticipated social norm was larger. This implies that the divergence from a socially desirable mode of action influences the magnitude of the bias.

Psychosocial stress, lifestyle and periodontal health.

BACKGROUND, AIMS: The hypothesis that psychosocial stress and lifestyle are related to periodontal status was tested. MATERIAL AND METHODS: The study was performed in 1997-98 in 10 areas in Lithuania (response rate 53%). Information comprised recordings of oral hygiene, calculated levels of remaining periodontal support and information about psychosocial and lifestyle factors. A hypothetical structure was tested in 2 age and gender subgroups by means of a structural equation model both for an overall fit and for the fit of individual parameters within the model. RESULTS: The hypothesised structure presented high confirmatory fit index values (CFI) in all subgroup models, i.e., CFI >0.94. However the probability value of 0.01 found in the older males model presented an unlikely event. When individual parameters within the models were tested, different misspecifications were found. Therefore the hypothesised structure needed to be revised and tested repeatedly. All revised models presented high CFI and probability values (p>0.35). The testing of individual parameters did not reveal any significantly misspecified parameters. CONCLUSIONS: The path between lifestyle and levels of remaining periodontal support was empirically supported in the present study. Although the pathway between psychosocial stress and remaining periodontal support was not empirically supported, there is reason to believe that such link is likely.