A retrospective analysis of caries treatment and development in relation to assessed caries risk in an adult population in Sweden

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.

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.

This study formulated two main conclusions: (i) adult patients with high or no/low caries represent different populations, that each contain distinct subpopulations, those who improve/impair or maintained their caries risk and disease progression. These groups need different strategies in disease treatment; and (ii) some preventive measures and non-operative treatments were associated with improvements in caries risk and maintenance, but the extent to which such treatments were given to high caries risk subjects was unacceptably low and not in line with present guidelines. Future research should evaluate what aspects influences dental caregivers to provide and succeed in caries preventive treatments also in patients at high risk to develop disease. In addition, future studies should examine how to improve implementation of preventive treatments as well as aim at separating the estimation of the effectiveness of such treatments from the effects of compliance.

US is responsible for development and quality control in the Public Dental Health organization in the County of Västerbotten. IJ is professor in Cariology with vast experience in epidemiology. KSG (DDS, PhD) is experienced in caries treatment in adult patients and in designing and conducting clinical trials.