Stop caries Stockholm : a caries-prevention program for children living in multicultural areas with low socioeconomic status

Abstract

Inequalities in oral health among children persist, despite more general improvements in recent decades. Dental caries still affects children in disadvantaged communities with a multicultural population, both more frequently and more severely. As caries is a disease that perseveres throughout life, it is important to prevent its development before it has begun. The present thesis describes effectiveness and costs of an expanded intervention program for toddlers in high-risk areas of Stockholm County. This thesis also investigates the effect of supplemental measures on surface level caries progression, and whether high-fluoride content supplements have any effect on select bacteria in the oral cavity.

Objectives: To evaluate the effectiveness of an expanded caries-preventive program in a 2-year, parallel cluster-randomized controlled trial on a cohort of toddlers living in multicultural areas of Stockholm County with a low socioeconomic status.

Patients and methods: Twenty-three dental clinics were stratified and randomized into one test group (n=1,652) and one reference group (n=1,751). Study participants began the intervention programs in 2011 at age 12 months and received the last intervention at age 36 months. The reference group received the standard caries-preventive program that was already in place once a year. The test group received the same and, in addition, supplemental measures that included fluoride varnish applications at 6-month intervals. The trial used the revised International Caries Detection and Assessment System (ICDAS II, hereafter referred to simply as ICDAS) to assess dental caries. Mean inter-examiner reliability based on clinical examination was κ=0.61 (first examination) and κ=0.73 (second examination) when an ICDAS score of 3 was used as the cut-off for cavitation. At the final examination after 2 years, oral bacterial samples from a convenience sample of toddlers (n=507) in select dental clinics were analyzed using checkerboard DNA–DNA hybridization. The health economic evaluation used predetermined intervention costs as well as costs retrieved from a systematic review of the dental records (n=1,346). The between-group difference in the 2-year increment of decayed, extracted, or filled surfaces (defs) was used in the cost-effectiveness calculations. Surfaces with ICDAS scores of 3-6 were considered decayed.

Results: At baseline (age 12 months), 5% of the toddlers had already developed signs of dental caries (ICDAS 1-6). One year later, we re-examined 80% (n=2,675) of all recruited study participants and 2 years later, 75% (n=2,536) when the toddlers were 36 months. At age 24 months, 7% of the children had developed initial stage decay (ICDAS 1-2) and 4%, moderate-to-severe decay (ICDAS 3-6). At age 36 months, dental caries (ICDAS 1-6) was seen in 23% and the prevalence of moderate-to-severe decay was 12%. No between-group differences occurred in prevalence or increment. Except on the mandibular incisors, which were rarely affected, caries development followed the eruption pattern of the teeth. Most affected were the buccal surfaces of the maxillary incisors, which had a caries progression index (PI) of 26% between baseline and the 1-year examinations, and 21% between the 1- and 2-year examinations. The PI is an average of all changes or progressions to a more severe stage of decay according to ICDAS. Healthy surfaces and surfaces with initial stage decay (ICDAS 1-2) were less likely to progress. Of the maxillary incisor buccal surfaces rating ICDAS 6 at the 1-year exam, 21% were extracted 1 year later. No between-group differences occurred in progression on the buccal surfaces of the maxillary incisors or the occlusal surfaces of the first primary molars. Biannual applications of fluoridated varnish with a high fluoride concentration had a minimal effect on the populations of oral microflora. Significant differences between the test and reference groups occurred only regarding S. oralis, which was less frequently seen in the reference group. Overall tooth brushing frequency during the course of the trial increased from 55% to 91%, between ages 12 and 36 months. Dental health care costs of the intervention were EUR 96 for the test group and EUR 72 for the intervention group. The difference in mean increment between the groups from baseline at 12 months to the follow-up at 36 months was 0.09 defs in favor of the test group, a number used as the base case in the incremental cost effectiveness ratio (ICER) calculations. From a dental health care perspective, the ICER was EUR 276; and from a societal perspective that also includes the parental investment in time, the cost per saved defs was EUR 464. Thus, the expanded intervention was not considered cost-effective.

Conclusions: Applications of fluoride varnish together with a standard caries-preventive program delivered every half year to toddlers between 12 and 36 months of age did not significantly reduce caries development compared with the caries-preventive program already in place. Application of fluoride varnish with a high concentration of fluoride did not affect surface level caries progression and had no significant effect on the composition of the oral microflora. The expanded program also increased costs from both health care and societal perspectives. The trial outcome did benefit the patient in many ways, however. We gained knowledge that allowed children to avoid unnecessary dental visits and which indicated better alternatives for resource allocation. One goal of preventive dental interventions is to foster oral hygiene skills in individuals for themselves and their children. We established regular habits in the use of fluoridated toothpaste at a young age in most of the participants. This may explain why the fluoride varnish applications had no effect as a supplemental measure to the caries-preventive program already in place; without the new regular tooth brushing habits, we would have expected a higher prevalence of caries than we found in the reference group. In a caries-preventive approach, early caries assessment is essential in order to tailor preventive measures to the needs of the individual. In our study, we could show that dental caries occurs as early as age 12 months; this supports clinical examinations in a dental setting beginning with the emergence of the first primary teeth.