1 Volume 21 2022 e226666 Original Article Braz J Oral Sci. 2022;21: e226666http://dx.doi.org/10.20396/bjos.v21i00.8666666 1 Dental Materials Department, School of Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, Brazil. 2 Department of Preventive and Social Dentistry, School of Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, Brazil. 3 Post-graduate Program in Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, Brazil. Corresponding author: Fabricio Mezzomo Collares +555133085198. fabricio.collares@ufrgs.br Rua Ramiro Barcelos, 2492. Porto Alegre, Rio Grande do Sul. Brazil. Editor: Altair A. Del Bel Cury Received: August 13, 2021 Accepted: April 2, 2022 Cost-related variables in the public purchase of dental materials for endodontic application: 10-year analysis Gabriela de Souza Balbinot1 , Roger Keller Celeste2 , Francisco Montagner3 , Fabricio Mezzomo Collares1,* Aim: This study analyzed public procurements for different endodontic materials used in the Brazilian public health system and evaluated the variables related to their cost. Methods: A time-series study was performed by screening materials for endodontic application in the public Brazilian Databank of Healthcare Prices from 2010 to 2019. Data were categorized according to material composition and clinical application. The collated variables were used in a multiple linear regression model to predict the impact of unit price in procurement processes. Results: A total of 5,973 procurement processes (1,524,693 items) were evaluated. Calcium hydroxides were found in 79% of the observations (4,669 processes). Prices drop each year by US$1.87 while MTAs and epoxy resins are increasingly purchased at higher prices (US$50.87; US$67.69, respectively). The microregion, the procurement modality, and the type of institution had no influence on unit prices in the adjusted model (p > 0.05). Conclusions: Calcium hydroxide-based materials were the cheapest and most frequently purchased endodontic materials in the public health care system. Novel formulations are being implemented into clinical practice over time and their cost may be a barrier to the broad application of materials such as MTAs, despite their effectiveness. Keywords: Dental materials. Endodontics. Public health dentistry. Translational science, biomedical. Costs and cost analysis. https://orcid.org/0000-0001-9076-2460 https://orcid.org/0000-0002-2468-6655 https://orcid.org/0000-0002-7850-0107 https://orcid.org/0000-0002-1382-0150 2 Balbinot et al. Braz J Oral Sci. 2022;21: e226666 Introduction Oral diseases are prevalent conditions that impact public health1 and an individual’s quality of life2. Dental caries and trauma frequently lead to damage of dental pulp tissue, contributing to pain and infection, which may progress to tooth loss. In these cases, endodontic treatments aim to reestablish periapical tissues by controlling bacterial infection in the root canal system, contributing to the maintenance of the tooth structure3,4. Access to these treatments is known to impact patients’ pain and comfort levels and represents an essential factor in the maintenance of oral health5. The prevalence of endodontic-related conditions varies among populations, and the need for intervention ranges from 4.8% to 6.3% for different populations5,6. The need for technology and a specialized dental workforce limits the implementation of end- odontic care in health care systems, especially considering the cost of these proce- dures and the impact they have on the public budget7,8. Endodontic interventions range from pulp capping to endodontic surgeries that require specific materials that modulate the healing process in most cases. These materials aim to stimulate new tissue formation using minimally invasive approaches for small pulp injuries and to seal the root canal space after tissue removal in cases where root canal treatment is needed9. The selection of materi- als is related to the type of intervention, professional experience or clinical skills, and the available evidence about the material’s performance. These factors should guide the dentist’s and the public system manager’s decision-making process in purchasing materials for clinical practice10. The procurement of materials in the public systems is a tool to understand the current clinical practice and the adherence to evidence-based knowledge in the endodontic field11. The Brazilian public health system includes dental treatment from primary to advanced care, including endodontic interventions12. The application of materi- als must consider both the effectiveness of treatments as well as the cost of these materials and their impact on the public budget. The screening for public expenditure in the biomedical fields helps to design cost-effective strategies for the public health- care system and is observed currently for medicines and health care materials13,14, including dental adhesives11, but no information regarding the endodontic materials is known. This study aims to collate and analyze endodontic materials’ public procure- ments from 2010 to 2019, investigating the purchase frequency of different materials and the variables related to their cost. Material and methods A time-series study was performed by screening the Brazilian Databank of Healthcare Prices (BDHP), a public database that collates secondary data of den- tal materials for endodontic application from January 1, 2010, to December 31, 2019. Data were organized in a single databank, and all analyses were conducted using STATA 14 (StataCorp LLC, TX, USA). The material description, the date of purchase, the institution that purchased the item, the product manufacturer, the number of purchased items, and the unit price were collated. Materials were 3 Balbinot et al. Braz J Oral Sci. 2022;21: e226666 divided into four different categories according to their composition: 1) Calcium hydroxide-based (CH) materials, 2) zinc oxide-eugenol (ZOE), 3) mineral trioxide aggregates (MTAs), and 4) epoxy resins (ERs). As secondary data was assessed, the classification took the materials manufacturer into consideration, and incon- sistencies in the relationship between these two variables were adjusted to avoid misinterpretation. Observations were further divided within each composition by considering their commercial presentation and, consequently, their application. The procurement processes were divided according to the type of institution that purchased the products and their location. The unit price was adjusted accord- ing to the National Wide Consumer Price Index (Índice Nacional de Preços ao Consumidor Amplo or IPCA) for each month/year over time. The adjusted Bra- zilian Reais (BRL) were converted to United States dollars (US$) using the daily exchange rate of the Central Bank of Brazil. The frequency in the procurement process and the number of purchased items were descriptively analyzed, and the average adjusted US$ prices were used in a multiple linear regression model using ordinary least squares. The categories that most frequently appear in the databank were used as a reference in the multiple linear regression analysis. Data were analyzed with bivariate tables and statistical significance was tested with a one-way analysis of variance. As part of regres- sion diagnostic, Studentized residuals larger than 3 were investigated for their impact on the assumption. Then, 17 (0.28% of the total number of observations) values larger than 12.37 were excluded. The multiple regression linear model was cluster adjusted, as an interclass correlation coefficient showed that 10.4% of data variability may have been related to the institution that purchased the mate- rial. This adjustment considered 789 institutions that registered processes in the databank. Results A total of 5,973 procurement processes were evaluated, resulting in 1,524,693 pur- chased items. Figure 1 shows the descriptive analysis of purchased items in each composition and for different commercial presentations. CHs-based corresponded to 79% of the procurement process (Fig.1A) and 64% (Fig.1C) of the overall number of purchased endodontic materials in the databank. The frequency of purchase for each composition over the years is found in Figure 2. The number of procurement processes increase over the years for all analyzed materials. 4 Balbinot et al. Braz J Oral Sci. 2022;21: e226666 A B C D CH ZOE MTA ER CH ZOE MTA ER Paste/Paste Powder SyringePowder/Liquid Number of procurement process Number of procurement process in each composition for different commercial presentation Number of purchased itens Number of purchased itens in each composition for different commercial presentation CH ZOE MTA ER CH ZOE MTA ER Paste 4% 6% 12% 79% 5% 6% 25% 64% Figure 1. Descriptive analysis for the number of the procurement process and the overall number of purchased materials from 2010 to 2019. The screening in public procurement described the number of the procurement process that were conducted to purchase different dental materials (A) and their different commercial presentations (B). The number of purchased items in each process was used to calculate the overall number of purchased items in each composition (C) and their commercial presentations (D). A B B C 1.000 800 600 400 200 0 Year Calcium hydroxides Zinc oxide-Eugenol MTA Epoxi Resin N um be r o f p ro cu re m en t p ro ce ss 2012 2013 2014 2015 2016 2017 2018 2019 1.000 1.200 1.400 800 600 400 200 0 MacroregionN um be r o f p ro cu re m en t p ro ce ss South Southeast Mid-west Northeast North 5.000 4.000 3.000 2.000 1.000 0 Procurement Modality N um be r o f p ro cu re m en t p ro ce ss Auction Bid-Waiver Other 2.500 3.000 4.000 3.500 2.000 1.500 1.000 500 0 Types of Institution N um be r o f p ro cu re m en t p ro ce ss Universities Other Federal Institutions Municipalities Figure 2. The procurement process for each composition, according to the analyzed categories. 5 Balbinot et al. Braz J Oral Sci. 2022;21: e226666 As shown in Table 1, all variables were statistically significant and were thus included in the adjusted model in Table 2. The adjusted model for the regression analysis is shown in Table 2. The prices among different material compositions show that CH (reference category) was the cheapest material in the analyzed data. ZOE sealers were purchased for US$6.19 more than the reference (p < 0.01) while ERs were shown to cost US$44.76 more than CH-based materials (p < 0.01). Year predicted a reduc- tion of US$1.87 in endodontic material unit prices (p < 0.01). Institution location did not modify the price of the materials, and the procurement processes that were con- ducted by bid-waiver were US$10.50 more expensive than the ones performed by auction. Municipalities paid less for the products than did other federal institutions (US$2.25; p < 0.01). The differences between manufacturer prices showed high vari- ation among the categories. Table 1. The average price and standard deviation were calculated for each category on the variables. The analysis was conducted considering the different compositions. Univariate analysis (US$) St.Dev Frequency P-Value Material Composition CH 12.41 19.20 4,669 ZOE 19.20 24.15 768 MTA 50.86 25.12 323 ER 67.69 24.46 308 <0.01 Year 2012 21.38 30.49 168 2013 22.13 33.63 635 2014 18.39 24.09 591 2015 13.96 20.04 718 2016 16.92 22.48 856 2017 19.73 27.31 905 2018 14.83 20.71 974 2019 15.95 19.84 1,121 <0.01 Macroregion South 18.46 29.48 1,315 Southeast 18.66 25.32 1,557 Mid-West 18.59 24.59 795 Northeast 15.14 19.37 1,519 North 15.46 19.50 782 <0.01 Procurement Modality Auction 16.65 27.12 5,159 Bid Waiver 21.82 23.74 774 Other 11.58 14.96 35 <0.01 Continue 6 Balbinot et al. Braz J Oral Sci. 2022;21: e226666 Continuation Type of Institution Universities 15.35 25.06 1,239 Other Federal Institutions 18.65 24.80 4,202 Municipalities 11.09 14.24 527 <0.01 Manufacturer AAF 5.38 6.13 83 Angelus 51.32 25.18 330 Biodinâmica 4.60 7.79 830 Caitech 8.23 5.28 4 Coltene 10.39 6.16 53 Dentsply 35.33 30.83 903 Iodontosul 2.95 2.95 94 Kavokerr 67.44 28.96 21 Maquira 2.45 3.56 366 Septodont 45.99 0 2 SS White 16.32 6.20 661 Technew 7.54 6.43 1,559 Ultradent 12.21 5.71 81 Other 23.76 33.44 981 <0.01 Table 2. Adjusted price differences (Coeff) from multiple linear regression of the procurement processes (n=5,968). Price Coeff (US$) 95% Conf. Interval Material Composition (Reference Category: Calcium Hydroxides) Zinc Oxide - Eugenol 6.19 3.31 9.06 MTA 16.99 11.05 22.93 Epoxy Resin 44.76 38.24 51.29 Year -1.87 -2.51 -1.22 Macroregion (Reference Category: Southeast) South 1.85 -2.94 6.64 Mid-West 0.82 -1.95 3.59 Northeast 0.03 -2.16 2.22 North -0.98 -3.28 1.30 Procurement Modality (Reference Category: Auction)  Bid Waiver 10.15 -34.68 14.30 Other 0.908 -4.70 6.51 Continue 7 Balbinot et al. Braz J Oral Sci. 2022;21: e226666 Continuation Type of Institution (Reference Category: Other Federal Institutions) Universities 0.17 -4.01 4.37 Municipalities -2.25 -5.17 0.67 Manufacturer (Reference Category: Technew) AAF -6.84 -9.11 -4.57 Angelus 31.44 25.53 37.34 Biodinâmica -3.10 -4.44 -1.76 Caitech -5.69 -10.10 -1.29 Coltene 1.37 -1.33 4.07 Dentsply 19.91 14.72 25.11 Iodontosul -5.64 -7.16 -4.12 Kavokerr 53.00 34.18 72.61 Maquira -2.50 -3.75 -1.25 Septodont 31.13 27.43 34.83 SSWhite 10.09 8.23 11.25 Ultradent 8.23 5.75 10.71 Other 20.85 -3.40 45.10 Cons 3782 2485 5079 Note: R2= 45.41%. Discussion Access to endodontic treatment in a public health system depends on different health care levels, as the complexity of treatments may vary according to the diagnosis and available resources for assistance15. Most endodontic therapies involve the applica- tion of the materials screened in the present analysis. Four material compositions were used to address the public purchases of endodontic materials between 2010 and 2019. The registered procurement process showed that CH-based products were the most purchased and cheapest materials during the analyzed period. Increasing purchases of MTAs and ER are observed despite their higher prices compared to CH-based materials. The linear model showed that a reduction in prices is expected. Procurement processes that were conducted with auction modality presented a reduced cost for the health care system. The selected materials were divided by composition based on well-known for- mulations commonly used for endodontic procedures in clinical practice (Fig.1). CH-based materials are indicated for several procedures with different commercial presentations as seen in Figure 1. This may be one reason why these are the most frequently purchased materials in the analyzed period. The purchase of CH-based materials, regardless of their presentation, was consistent over the years as the number of registered processes increased (Fig.2). Their application as an intracanal medication in the paste presentation justifies the high number of the purchased product while the most purchased presentation is the paste/paste indicated for 8 Balbinot et al. Braz J Oral Sci. 2022;21: e226666 pulp-capping procedures16. The high number of procurement processes is main- tained in this case despite the recent clinical evidence that shows MTAs’ superior performance in pulp-capping treatments17. Recently, MTAs have been compared to CH and pulpotomy dressing agents for pulpotomy treatment in immature perma- nent teeth18, with a slightly greater benefit found for MTAs in a 12-month analysis. In addition, MTAs had overall better clinical and radiographic success rates for end- odontic treatment in immature necrotic permanent teeth when compared to CH replacement or revascularization strategies19. Although Figure 2 shows an increase in MTA purchases from 2015 to 2019, these purchases represent only 6% of the total purchased materials (Fig. 1). As the MTA materials were more recently devel- oped, it was expected that they would occupy a smaller portion of the market share while their increasing applications and clinical effectivity were reported. The extensive clinical use of CH-based products and their low costs may be import- ant factors in the decision-making of dentists and managers. The procurement processes for CH-based materials were conducted with lower average prices while MTAs areUS$16.99 is more expensive than CHs (Table 2). Although these two com- positions are not necessarily indicated for the same treatment in all clinical condi- tions, treatments with MTAs could represent a higher cost for the system. MTAs’ cost is known to be a drawback for its application in clinical practice, and it may be especially critical for a large-scale public system where this could affect the public budget and access to this treatment and where budget cuts are common20. Still, it is essential to consider the clinical and laboratory data that has recently shown better outcomes with MTAs than CH-based materials16-18,21. Besides clinical suc- cess, MTAs’ use may increase patient compliance and reduce the number of dental appointments, impacting the overall cost of treatment22. A prospective randomized clinical trial reported that 4 out of 15 teeth treated with CH as a material for inducing root apex closure in immature necrotic teeth exhibited coronal or radicular frac- tures after 12 months; no tooth loss was observed in MTA-treated teeth21. It must be considered that premature tooth loss may have negative psychological effects on the patient, on the patient’s quality of life, and the costs for the health system8. Although the implementation of novel technologies in health care may take time and there are still clinical situations that may benefit from CH, novel materials are constantly under development and investigation. The generation of novel evidence may shift the standard of care when new and effective products are available. While MTAs show promising results in regenerative therapies, the need for translation of current evidence and the impact on the public budget may limit its use in the public health care system7. Root canal sealers were also found in the databank, and as observed in Figure 1, the ZOE sealers were purchased in 710 procurement processes, representing 25% of the total number of purchased materials. The application of these sealers for root canal filling is well established and is observed in the purchases made for the powder and liquid commercial presentation (Fig. 1B and 1D). The high number of procurement processes and the consistency of these numbers over the years may be due to these materials’ long clinical use9. Besides the popularity of ZOE, its price may play an important role in the procurement of these materials, as observed in 9 Balbinot et al. Braz J Oral Sci. 2022;21: e226666 the linear model (Table 2). The unit price for these sealers is reduced compared to the reference, but when ZOE coefficients are compared to that of ER and MTAs, it is possible to observe decreasing values in the adjusted model (US$6.19; p < 0.05). ER was the most expensive material (Fig.1) and, although it represents a small frac- tion of the total amount of endodontic materials (4%), an increase in the number of procurements was observed throughout 2016. Although evident physicochemical and biological differences are observed between root canal sealers’ compositions9, there is still no evidence for superior clinical performance for any of these materials in root-filling procedures9. The establishment of evidence-based protocols, in this case, requires further high-quality analysis to provide information for practitioners and managers in the decision-making process. The implementation of guidelines and innovative materials requires solid scientific evidence and the diffusion of knowledge for clinical practice. The absence of synthesized evidence, in this case, may contribute to the broad utilization of well-known ZOE sealers. The increase in ERs and MTAs purchases may represent modifications of clinical practice that must consider the cost-effectiveness of the treatments in the decision-making pro- cess. It should be noted that besides direct and indirect costs related to treatment and a material’s cost on the public expenditure, more effective and lasting therapies directly impact the need for reinterventions and may be beneficial for impacting the dental health in the population23. Public procurement processes were analyzed considering different variables that may affect dentists’ and managers’ choices. The year of purchase was shown to significantly predict a reduction in unit prices (Table 2). A drop of US$1.87 was pre- dicted for each year (Table 2; p < 0.01), and this may be related to the increased number of available materials on the market24. The procurement modality predicts a reduction, and these findings follow the recommendations of regulatory agen- cies that classify auctions as the procurement modality for public purchases due to a reduction in costs and an increase in transparency25. The manufacturer also modifies the unit price. Although a high variation is observed in the linear coef- ficients, it is possible to observe that differences in prices are driven by mate- rial compositions (Table 2). The ER and MTA manufacturers presented higher coefficients than the reference category known to produce mainly CH-based materials. Comparisons within each composition were not possible in the cur- rent model due to the variations in the commercial presentations. The follow-up in the analysis of the databank in the next years may provide enough data for further analysis. The information provided by this analysis may contribute to the formulation of pub- lic policies to the application of endodontic materials considering the laboratory and clinical evidence and the need for rationality in public purchases. Despite a large number of laboratory studies on dental materials for endodontic purposes, a robust synthesis of knowledge with high-quality clinical studies is required to guar- antee clinically and cost-effective treatments26 and to reduce the influence of the personal preferences of professionals. Variations in recommended protocols and the lack of a conclusive synthesis may jeopardize scientific-knowledge diffusion and the establishment of standardized clinical practice. The continuous analysis of 10 Balbinot et al. Braz J Oral Sci. 2022;21: e226666 the purchased products could provide insights into the current standard of care in endodontics. With the present findings, it is possible to understand the modifica- tions in clinical behavior over the system and to assess their influence on the public budget and the quality of treatments provided in the field. Acknowledgements G.S.B would like to thank CAPES “Coordenação de Aperfeiçoamento de Pessoal de Nível Superior” - Brazil - Finance Code 001-Schoolarship. Data availability Datasets related to this article will be available upon request to the corresponding author. Conflict of Interest None Author Contribution G.S.B: Conception and design of the work; Analysis and interpretation of data; Draft- ing. R.K.C: Analysis and interpretation of data; Work revision for important intellectual content. F.M: Work revision for important intellectual content; Final approval of the version to be published. F.M.C: Conception and design of the work; Interpretation of data; Final approval of the version to be published References 1. 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