Economic evaluation (EE) studies have been undertaken in dentistry since the late 20th century as economic data are useful to policymakers to develop guidelines and set future directions for oral health services . EE is a systematic analysis that considers all costs and outcomes associated with healthcare interventions, and can be defined as the ‘comparative analysis of alternative courses of action in terms of their costs and consequences’ [10, 11]. EE studies have been widely used in healthcare systems for the assessment of various programs, including those focused on prevention, diagnosis and treatment . Stephen and Campbell first applied EE to dentistry in 1978, when they conducted a three-year cost-benefit analysis of fluorinated tablets in a Scottish school . More recently, EE has been used in endodontic treatment , periodontal treatment  and prosthodontic and implant treatment [16, 17]. The results of the fourth national oral health epidemiological survey of China, released in 2015, showed that the prevalence rate of caries in the primary teeth of 5-year-old children was 71.9%, and that of the permanent teeth of 12-year-old children was 34.5%. This high rate made research in China a priority. A more economical treatment method for children's oral diseases can effectively increase treatment rate and improve the status of children's oral health. The innovation of this study is the combination of cost and clinical effect, which allowed us to find a method that was not only more effective but also more economical for primary molar treatment.
This clinical investigation was conducted to compare the treatment effect and cost of IPT, pulpotomy and pulpectomy. It included a cost-effectiveness analysis focused on the molars meeting the indications partially overlapping of these three treatments to compare the cost, survival time and survival time: cost ratio. Comparing IPT with pulpotomy, IPT had a significantly lower survival time: cost ratio and was therefore more economical during the 3-year follow up although there was no significant difference in survival time. From this, we can suggest that IPT seems to be a more economical choice for primary molars with deep caries. In addition, after analyzing the teeth that failed 1 year after IPT, we found that seven of the nine failed teeth were due to subsequent symptoms of pulpitis or even periapical inflammation. During the pulpotomy, dentists can judge the condition of pulp inflammation according to the pulp traits and hemorrhage, and then determine whether the tooth is suitable for treatment with pulpotomy. However, during IPT, dentists cannot directly observe the pulp state, and there is no gold standard for determining this in deciduous teeth in clinical practice for IPT. The choice of treatment methods requires a comprehensive consideration of medical history, clinical examination and radiographic examination. The identification of deep caries and pulpitis in primary teeth is difficult for the pediatric dentist, and is the main reason why the failure rate of the IPT group was significantly higher than the other two groups within 1 year. However, although the probability of failure after IPT was significantly higher than after pulpotomy and pulpectomy, the survival time: cost ratio of IPT was still significantly higher than pulpotomy after including the cost of subsequent pulpectomy. This suggests that IPT should be used as much as possible when the pulp is in good condition to achieve better therapeutic effects and cost savings in primary molars.
Compared with pulpectomy, pulpotomy showed a significantly higher survival time and survival time: cost ratio, indicating that it was more economical. This suggested that for primary molars whose coronal pulp is in a critical state, pulpotomy can achieve better therapeutic effects and cost savings.
Previous studies that compared the three treatments looked at differences in clinical effects, and this is the first to evaluate them economically. The success rate of MTA pulpotomy is considered to be between 91% and 100% for 12–38 months, and the success rate for IPT for 6–50 months is approximately the same: between 90% and 95% . Other studies, although not directly comparing IPT and MTA pulpotomy, suggested that IPT can achieve a survival rate of 96% in 3 years and MTA pulpotomy can achieve a survival rate of 95% in 2 years; these are both considered high survival rates [19, 20]. A 2017 study concluded that the success rate of MTA pulpotomy and Vitapex pulpectomy was 90% and 79%, respectively, a statistically significant difference . Most previous studies used survival rate as a valuation index. In this study, although survival time was used as an evaluation index for clinical effects, the results were essentially consistent with previous studies that found no significant difference between the clinical treatment effects of MTA pulpotomy and IPT; however, pulpotomy was significantly better than pulpectomy. The advantage of using survival time is that we can combine treatment effects with costs and conduct health economics assessments, which is the main purpose of this study.
However, there were some limitations in this study. First, although the number of children attending our department is large, regular follow-up is limited, resulting in a limited sample. Secondly, the results of this study can only objectively reflect an area of equal economic level in China. It does not reflect the actual situation of other hospitals, not to mention other regions and countries. If this conclusion is extended to other regions or countries, multi-center and larger studies are needed. Finally, there were significant differences in treatments and restoration methods among the groups. Children included were treated under GA or as out-patients and molars were restored by resin filling or SSC. These differences may have affected the results. However, another study by our group, which selected subjects using the same database, found that different treatments and restoration methods had no impact on survival after treatment . Therefore, in this study we assumed the differences in treatment and restoration method had no significant impact on the results.