Background
Caries is the most common lifestyle-influenced disease in children and adults worldwide[
1,
2]. Although preventable, the treatment of primary and secondary caries, and replacement of restorations are the most common treatments dentists perform[
3,
4]. Restorative treatments are expensive for the individual and society. If left untreated, the disease might also cause severe pain, eating problems, social stigma, and reduced disability-adjusted life year (DALY)[
1,
5]. The disease can be prevented and even reversed at its early stages by appropriate lifestyle adjustments[
6‐
8]. Over the latest decades, access to regular dental care combined with increased awareness of the benefits of healthy teeth, increased systematic use of fluoride, and improved oral hygiene has led to significantly decreased mean caries prevalence, increased number of remaining teeth, and decreased prevalence of edentulous subjects in many parts of the world, including the Scandinavian countries[
9‐
12]. However, the reduced mean caries prevalence hides a skewed disease distribution, where approximately 15-20% of the population remains with high disease activity and accounts for approximately 60% of caries development[
13].
Successful treatment of diseases influenced by lifestyle, such as dental caries, cardiovascular diseases, and type-2 diabetes, relies on patient long-term compliance with risk factor management as well as on appropriate attention from the profession. For caries management, this means that dentists should identify an individual’s risk profile for disease development/progression and encourage patients to decrease their sugar intake, improve their oral hygiene, and increase fluoride use and frequency, all lifestyle actions that reduce cariogenic bacterial load. Therefore, caries risk assessment and risk factor profiling is recommended to ensure appropriate and early prevention and treatment of caries[
14]. To individualize caries treatments and recall periods, most county councils in Sweden recommend that dentists use individual caries risk profiling[
15]. This public dental care concept has recently been identified by Ito et al.[
14] as a practical and effective strategy: “If people with higher risks can be identified and given improved intensive preventive care, this could offer both an efficient way of promoting individual and community oral health and a more economic use of health resources”.
Västerbotten County, located in northern Sweden, has required caries risk profiling for adults since 2002. Simultaneously, dentists have been urged to provide individualised preventive and non-operative caries measures in accordance with the minimally invasive caries concept and national guidelines[
16,
17].
The aim of the present study was to evaluate the accordance between recommended treatment and a patient’s risk to develop caries by comparing caries development and clinical management of two patient groups: patients with no or low risk and patients with high risk for developing caries. Special attention was paid to caries preventive and non-operative measures. In addition, this study examines the reclassification of subjects into a lower or higher caries risk group. The study cohort comprised patients who regularly attended Public Dental Service clinics from 2005 to 2011 in Västerbotten County, Sweden.
Methods
Study design
This retrospective cohort study evaluates caries status and treatment from patient records for adults (25 years and older) who attended one of 33 Public Dental Service clinics in Västerbotten County, Sweden as recall patients from 2005 through 2011. The study is part of a larger cohort study on caries-lifestyle associations approved by the regional ethical review board in Umeå, Sweden.
Caries scoring and risk assessment
Since 1999, an electronic system (T4) has been used for dental records at all Public Health Care clinics in Västerbotten. The system was developed by the Medical Insurance Agency (MIA) (Atlanta, USA), but is now marketed by Carestream Health (Toronto, Canada). The records include date of visit, oral (caries, periodontal, endodontic, soft tissues, plaque, etc.) and medical status, medication use, tobacco use, notes on specific examinations such as saliva and bacteria assessment, treatments and their costs, and type of recall system used. At each recall visit, a dentist or dental hygienist gave the patient a full oral examination. These examinations took place in fully-equipped dental offices and included at least bitewing x-rays in all patients where the approximal surfaces could not be inspected visually. The recall visits typically took place between six and 24 months after the initial visits. All 33 public dental health clinics use standardised examination routines for caries and periodontal disease. The dentists or hygienists conducted the caries examination using a mirror, probe, and x-rays, and scored lesions for enamel (initial) and dentine (manifest) caries[
18]. The caries were classified either as Decayed, Missing, and Filled Teeth (DMFT) or as Decayed, Missing, and Filled Surfaces (DMFS).
In 2002, Västerbotten introduced mandatory assessment of risk – general, caries, periodontal, and technical risk (Table
1). Together, these form an overall risk score used when considering treatment plans and recall schedules. Risk assessment is repeated at every recall visit. Implementation of the risk assessment procedure in 2002 was accompanied by thorough education and repeated calibration exercises at each of the 33 clinics.
Table 1
Overview of risk categories and criteria for risk assessment used in the County Council of Västerbotten, Sweden
General | • No disease or medication affecting teeth or gums | • Disease and/or medication with possible effect on teeth or gums | • Disease or medication with significant effect on teeth and gums |
• Good oral hygiene | • Mediocre oral hygiene | • Poor oral hygiene |
• Adequate diet and intake frequency | • Partly inadequate diet | • Inadequate diet |
• Moderate dental anxiety | • Severe dental anxiety |
• Smoker or snuff user | • Heavy smoker (>20 cigarettes/day) |
Caries | • No active enamel or dentin caries lesions | • 1-2 new caries lesions on caries prone surfaces | • ≥3 new caries lesions |
• New or moderate progression of enamel lesions | • Extensive progression of several enamel lesions |
• Lesions on non caries-prone surfaces |
Periodontal | • Periodontal health | • Periodontitis experience | • Active periodontal disease with clinical and radio-graphic attachment loss |
• Gingivitis and/or supragingival calculus | • Localized periodontal problems/signs of local bone loss | • Subgingival calculus |
• Bleeding-free gingiva and no pocket exceeding >5 mm | • Bleeding and pocket depth of 5–6 mm | • Peri-implantitis |
Technical | • Intact teeth or few restorations | • Single large restoration | • Several large restorations |
• Single root canal treatment of good quality | • Single restoration extending close to the pulp | • Several root canal treatments or root canal treatments of inadequate quality |
• Single crown or short bridge of good quality | • >1 root canal treatment of good quality | • Wisdom tooth requiring surgery |
• No or minimal abrasion of teeth | • Erupting wisdom tooth in the lower jaw | • Tooth grinding/TMD pain |
• Moderate abrasion of teeth/TMD pain | • Extensive erosion |
• Tongue/lip piercing | • Tongue or lip piercing with damaged teeth or mucosa |
• Crowns and/or bridges on healthy teeth with good occlusion | • Extensive teeth or implant supported constructions |
| • Full or partial denture |
Study population
In 2005, there were 196 998 adult inhabitants in Västerbotten County. Of these, 76 320 (39%) were registered as recall patients for complete dental care within the Public Dental Service. From this group, 42 276 had a regular dental examination in 2005 and 42% of these had a recall visit in 2011. In 2005, 35 896 adult patients (84.9% of all recall visits that year) had caries risk scored. In total, 44.3% of these patients were estimated to have no or low caries risk, 43% were estimated to have moderate caries risk, and 12.7% were estimated to have high caries risk. For the present study, 200 25–65 year-olds with high caries risk at the 2005 examination and with a recall visit in 2011 were randomly selected. This group was referred to as the “high caries risk group”. Selection was done to give equal proportions by sex, ten-year age groups, coast (more urban) areas, and inland (more rural) areas. An equally sized and proportionally balanced control group with no/low caries risk was randomly selected. This group was referred to as the “no/low caries risk group”. To ensure an 80% power of detecting difference at α = 0.05, the group sizes were based on expected annual caries incidence among high caries risk subjects in the Västerbotten population (mean 1.3 (SD 0.5) new surfaces/year). To account for a possible reduction in caries incidence over time, the group sizes were set to 200 subjects.
Data retrieval from dental records
Three experienced dentists retrieved information on number of visits, type of personnel seen at the visit, caries risk score, medical condition and medication, use of tobacco, and type of treatment or counselling from patient records. Information on number of teeth, tooth status, clinic, and costs for operative and non-operative treatments were from data registers kept at the County Council. Calibration of the three dentists was achieved during the study protocol construction, and by evaluating and comparing an independent. i.e. not part of the study sample, selection of ten high caries risk and ten no/low caries risk. This strategy resolved any ambiguities in the protocol and among the examiners. Next, a template for interpretations was created and added to the review protocol. If any ambiguity appeared during the review, all three examiners discussed the issue to reach consensus.
Data handling and statistical analysis
Data handling, descriptive analyses, and regression modelling were performed using SPSS version 20 software (SPSS Inc., Chicago, IL) and principal component analysis (PCA) using SIMCA P+, version 12.0 (Umetrics AB, Umeå, Sweden).
Estimated marginal means for caries prevalence and incidence were calculated among participants using general linear regression modelling (glm), including sex, age group, and clinic as covariates. Differences between means for the two caries risk groups were tested with Student’s t-test and among more groups (here clinics) by analysis of variance (ANOVA). Correlations between variables were calculated as Spearman or Fischer correlations depending on the distribution of observations. For categorical variables, distributions of numbers were tested using the Chi^2-test. P-values <0.05 were considered statistically significant.
Logistic regression was used to identify variables associated with (i) having a lower caries risk in 2011 if having a high caries risk in 2005 (n = 200) and (ii) maintaining a low/no caries risk in 2011 if having a low/no caries risk in 2005 (n = 200). The models included ten-year age group, sex, living region, and total numbers of scheduled visits to the dental office, and of visits that included counselling on tooth brushing with fluoridated toothpaste, the use of additional fluoride, dietary habits, and/or oral hygiene instruction.
Principal component analysis (PCA) was used to search for clustering among the study participants by caries risk group allocation or alteration in caries risk level from 2005 to 2011. The model searching for clustering of participants by caries risk group allocation included data for 2005 (ten-year age group, sex, living region, dental status, tobacco use, clinic, health condition, use of medication, and use of fluoride). The model searching for clustering of participants according to change in caries risk level from 2005 to 2011 also included information from 2011 on the variables listed for the logistic regression. Variables were autoscaled to unit variance before entering them into the PCA model, and clustering of subjects were displayed in a score-loading plot.
Discussion
The present study evaluated caries development and clinical management of adult patients classified with high risk and activity of caries and compared these findings with subjects classified with low/no risk and activity of caries. The study was performed in a county with organized dental care that provided guidelines for prevention and non-operative treatments in caries management. Three main findings were identified: (
i) subjects at high risk of developing caries continued to develop disease at a higher level than low/no risk subjects, and nearly 50% of these remained high risk despite significantly more frequent visits to the dental clinic than those with low risk; (
ii) preventive measures were according to records at an unexpectedly low level for high risk subjects and only marginally different in type and amount for low risk subjects; and (
iii) preventive measures, especially the recommendation to use fluoridated toothpaste, were associated with a reclassification of high caries risk subjects into moderate or low risk. Although the use of fluoridated toothpaste has been established to improve caries prevention in children and adolescents[
19], in adults there is little evidence that such measures are helpful. Therefore, it was noteworthy that counselling on tooth brushing with fluoridated toothpaste, even if far from optimal, was associated with a lowering of the risk score in those originally scored with a high risk.
In Västerbotten, the Public Dental Service provides regular dental care to virtually all residents aged 20 and under and nearly 40% of the adult residents. Dental care is free up to the age of 20 and subsidized for anyone 20 years and older. Most patients attend the same dental clinic on a long-term basis. In general, recall visits are between one and two years. These characteristics, as well as the overall socio-economic profile, are not considered to differ substantially between adults treated by the Public Dental Service or by private clinics[
12,
20]. Thus, a strength of this study is that its subjects represent the general population of the area. It has previously been found that behaviours and attitudes towards oral disease prevention differ between clinics[
21], a finding that was supported in the present study by the wide variation in proportion of patients reducing their high or maintaining their low/no caries risk level. Thus, another strength was that all clinics in the county were represented, reducing a potential impact from systematic errors. Furthermore, means were standardized for clinics to adjust for the uneven proportion of subjects from the different clinics after sample selection. A weakness of the study relates to the retrospective evaluation of patient records as this approach could result in underreporting of treatments and counselling. In addition, the retrospective design may be a limitation since ambiguities could not be resolved with the caregiver(s); however, this situation could be seen as a strength because treatments and recordings were not intentionally or unintentionally adjusted to a study situation. An additional potential source of error relates to the validity of the caries scoring, and especially that of secondary caries. It cannot be excluded that scoring of secondary caries is biased by inclusion of marginal fractures of restorations. Hence, the increase in secondary caries from 2009 and 2011 might, at least partly, reflect an increased number of restorations and restoration fractures. We do, however, not think this is a major source of error based on the facts that the digital recording system has a specific code for restoration fracture, and that during the years 2005 to 2009 incident secondary caries decreased though the number of restorations increased steadily, and there is no reason recording habits would change significantly over a few years in a stable staffing.
The goal for the national Public Dental Service, which is also the goal for Västerbotten, is to achieve and maintain good oral health in all citizens[
17]. The primary guideline is that all patients should be knowledgeable on basic oral hygiene procedures and on the benefit of using fluoridated toothpaste. In addition, a high-risk strategy targeting the individual risk profile should be used in highly diseased individuals or individuals susceptible to disease. Therefore, it was surprising that information on tooth brushing and use of fluoridated toothpaste was documented in only half of the 400 participants and even more surprising that the proportions receiving such information, or any other preventive counselling, did not differ substantially between the high and low/no caries risk groups at baseline or over the entire seven-year period. It was also unexpected that the number of visits to a dental hygienist did not differ by the two study groups. There are several theoretical explanations for this. For example, information may have been given but not recorded and patients who had such information before 2005 may have already been practising good oral hygiene and using fluoridated toothpaste. However, if the latter were true, one would expect to find this documented at least in the high-risk group. This was rarely the case. Another possible explanation relates to dentists’ and dental hygienists’ lack of trust that their patients will follow through with prevention protocols. For example, Sbaraini et al. found that many Australian dentists considered some patients too “unreliable” to benefit from prevention counselling, so tangible restorative treatment offered “value for money”[
22]. Whether this reflects the situation in Sweden can only be speculated on, but given that both countries have a similar system for dental education and care, it cannot be excluded. Still, the overall conclusion is that compliance with the guidelines on caries prevention and treatment are poorly followed, but this conclusion needs further study.
The present findings of a seemingly non-optimal compliance with the Swedish guidelines for caries treatment and prevention and the continuous need for frequent visits to the clinic for high risk patients is fully in line with Rindal et al.’s findings[
23]. A portion of the limited effect of counselling and treatment certainly relates to limited compliance among patients and eventually shortcomings in treatment efficacies, such as reported from randomized clinical trials with high-risk strategies[
24,
25]. The present study does not allow for a distinction between the impact of compliance among patients and caregivers. Such a distinction would help researchers and dentists design strategies that improve disease outcome. As with high-risk patients, low/no risk patients should have a level of treatment commensurate with their risk and prevention goals. It cannot be evaluated whether the present results reveal an over-treatment in low risk subjects, but the lack of difference in treatment intensity in the two groups opens the question.
Disease risk assessment is a generally accepted way to identify patients who need intensified care versus those who do not. The concept, however, relies on the accuracy of the risk assessment instrument and that appropriate treatments are practiced[
8]. None of the presently suggested markers for caries risk have been shown to have satisfactory sensitivity and specificity irrespective of whether clinical or biological parameters were tested. This lack of specificity and sensitivity may reflect the fact that the optimal combination of markers has yet to be identified, and that caries patients represent distinct subgroups where lifestyle factors are more influential for some patients and biological susceptibility is more prevalent in others[
26]. The risk scoring system used at the study clinics rely mainly on disease activity, even though general disease, medication, and dentist’s opinion are considered. Apparently, this system was sufficient to distinguish between patients with low or high caries risk, as those scored with high risk both have higher caries prevalence and a higher caries incidence over the seven-year period. However, the risk scoring system does not guide the design of the individual treatment plans as one based on individually-assessed biological and behaviour risk factors.
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Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
All authors participated in data retrieval and manuscript processing. US initiated the study, and IJ was responsible for data analysis. KSG finalized the manuscript. All the authors approved the final version.