Sealant reimbursement for the first molar began in 2009 for individuals aged 6–14 in December 2009. Through two revisions, the second molar was added to the coverage in October 2012. In July 2013, the age range was expanded to those under 18 years of age. We aimed to identify the effectiveness of the sealant reimbursement policy for the first molar for those aged 11–20 years (who benefited from the beginning of reimbursement following the implementation of the sealant coverage in Korea) by identifying differences in oral health indices between beneficiaries and non-beneficiaries as well as associations with sociodemographic characteristics.
First, the sealant holder rate increased by 7.7% (27.8% for the non-beneficiaries and 35.5% for the beneficiaries) and the mean number of first molars with sealant per capita doubled (from 0.45 for non-beneficiaries to 0.83 for beneficiaries). This increase is estimated to be affected by the sealant reimbursement policy. However, this is low compared with the two-thirds of Danish 15-year-olds who have at least one sealant [17], as Korea has not yet reached one sealant per person. The main reason for the increase in the sealant holding rate not meeting the expectations was the low-income groups, as there was a relatively high cost-sharing ratio of 30–60% for the first 7 years (from December 2009 to September 2017), which may have raised the threshold for dental access. Before reimbursement, the cost of one sealant is approximately $34, of which 30–60% is approximately $10–20. It can be estimated that the cost will be about $40 to $80 per person, provided that all four first molars are treated per person. These costs are considered to be very expensive for the vulnerable groups.
Prior studies have shown that high partial copayments will be particularly burdensome for low-income individuals [18]. The relationship between socioeconomic factors and sealant has weakened after the reimbursement policy, but still existed [6]. In this study, there was a significant difference in sealant retention according to parental education and household income. Similar studies have reported that household income is associated with a higher sealant experience. [19].
Meanwhile, some developed countries provide free preventive dental services for children and adolescents. In the French dental system, children and adults are eligible for free preventive dental services every 3 years from 3 to 24 years of age [20]. In addition, Sweden regards children’s dental care as part of the nation's universal welfare, and services for dental health for children and adolescents up to 19 years of age are provided free of charge [21].
In 2012, Korea piloted the family dentist system for vulnerable children under 18 years of age living in Seoul for the first time [22]. Since then, this system has been introduced and implemented in some areas. The family dentist system in Korea is a scheme that provides dental medical services such as oral examination, preventive care, and treatment in connection with the public health center and local dental clinic for low-income children [23]. This system has shown positive effects in terms of oral health awareness and behavior, and it is also very positive that students who have low access to dental healthcare and who do not receive dental services can be beneficiaries of the system [24]. Since 2020, the family dentist system for children has been piloted as a government-led project. In addition, since October 2017, deductibles have been reduced from 30–10% because of sealant reimbursement [25]. Nevertheless, in order to provide dental preventive services to vulnerable groups who do not benefit from the reimbursement system, schemes such as the family dentist system for children should be promoted, and measures to supplement the limitations and minimize problems between the systems should be implemented.
The proportion individuals with decay-missing-filled permanent teeth decreased by about quarter-fold in the beneficiaries compared with the non-beneficiaries, 2.09 in the non-beneficiaries and 1.57 in the beneficiaries. In addition, the single-crown retention rate decreased 2.7% (8.7% for the non-beneficiaries to 6.0% for the beneficiaries). The number of single crowns per person decreased by 0.03 (from 0.11 to 0.08), but this was not statistically significant. In other words, both the occurrence of caries and fixed dentures decreased, but these were not significant changes when compared to values before the reimbursement policy. In addition, according to the outpatient ranking of multi-frequency diseases in Korea, dental caries in 2010–2018 ranked 6-7th, which indicates no significant change over 8 years [26]. It is supposed that dental caries are decreasing in children and adolescents, but the caries that have advanced to adulthood and need treatment have not been reduced.
As a result, there seems to be a need to determine how long sealant treatment in children and adolescents can last into adulthood. Some previous studies have shown that the retention and lifespan of sealants act as a beneficial factor in the prevention of tooth decay [27, 28]. That is, after sealant treatment, if left out partially, the risk of caries seems inevitable. Choi et al. insisted on the factors that can improve retention of sealant treatment and asserted the importance of follow-up management to institutionalize and manage return visits after treatment [29]. Although sealant is less costly and more effective as a preventive policy than the expensive post-treatment of caries, the caries prevention effect of sealant will not last into adulthood without considering the loss and maintenance of sealant. In the future, a follow-up system that can ensure sealant retention will need to be implemented.
This study was meaningful as it confirmed the change in oral health indicators and the difference of sociodemographic factors after the sealant reimbursement policy was implemented. However, there were some limitations. First, we could not track the age of the participants limited to cross-sectional studies; moreover, there were restrictions in identifying causal relationships, although associations between oral health indicators and sociodemographic characteristics were identified. In the future, cohort studies are needed to track the experience with sealant treatment to confirm changes in oral health indices and promote sealant maintenance.