# Universal Dental Adhesives: Cost-Effectiveness and Duration of Use
## 4 Discussion
In our study, however, the primary parameter of concern was the price, and a negative value would actually indicate more cost-effectiveness (benefit). In our findings, we found that the ICER value of OB value was negative; however, there was no significant difference among the tested adhesives based on statistical analysis. This can be explained by the high amount of waste associated with OB adhesive and the low efficacy of the GP, both compared to the TN. In this study, we presented several parameters that dental clinicians might want to look into and use as a guide for purchasing the most cost-effective adhesive that would fit their budgets. Taking into consideration all of the CEA and relative parameters, the TN adhesive seems to be the most cost-effective. Although the TN adhesive was associated with the highest ACER cost, compared to the three other adhesives with a capacity of 5 mL, TN was the most effective and efficient with a capacity of only 2 mL. In addition, there was no difference in the incremental cost associated with this adhesive. The fact that the TN adhesive can be applied directly onto the tooth eliminates the additional cost and waste associated with purchasing microbrush applicators and dosing plates required while using adhesives delivered in conventional bottles. Similar to other in vitro studies, this investigation has some limitations. First, the study was not conducted in a clinical setting in which variable sizes and geometries of the cavities might affect the data. However, a laboratory approach was chosen in order to maintain low variability in the relevant factors, including the utilized cavity and the other conditions associated with the procedure. In addition, one of the major drawbacks of the ICER approach in this study was the use of one certain adhesive (the SB adhesive) as reference for comparison. Using another adhesive as a reference can potentially change the results and the data interpretation [20]. Moreover, we were not able to assess the incremental cost of the reference adhesive. However, SB is readily available in the market and it was used in multiple investigations previously [14, 15, 16]. Lastly, there was some difficulty in standardizing the applied force by which the adhesive bottles were squeezed in case of the SB, OB, and GP adhesives. This might have caused some variability in the amount of material dispensed from each adhesive on different occasions. However, one operator conducted the whole study in order to minimize the potential error. Taking all of the CEA parameters into consideration, TN available in VivaPen seems to be the most efficient and cost-effective adhesive. Although the GP has an integrated feature to control the dispensing of the material, the outcome was not as efficient. SB adhesive was the least efficient when the performance was related to its price. The bottle of the OB adhesive has no features to control the amount of the material dispensed, which made this adhesive the least efficient with low number of applications. Conceptualization: H.M.N. ; methodology: A.A.B. and H.M.N. ; formal analysis: A.A.B. and H.M.N. ; investigation: A.A.B. ; resources: H.M.N. ; data curation: A.A.B. and H.M.N. ; writing--original draft preparation: A.A.B. ; writing--review and editing: H.M.N. ; visualization: A.A.B. ; funding acquisition: H.M.N. All authors have read and agreed to the published version of the manuscript. **Funding:** This project was funded by Deanship of Scientific Research (DSR), King Abdulaziz University, Jeddah, Saudi Arabia, under grant No. (DF-049-165-1441). The authors gratefully acknowledge DSR technical and financial support. **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable. **Data Availability Statement:** The data presented in this study are available on request from the corresponding author. **Conflicts of Interest:** The authors declare no conflict of interest. VivaPen adhesive and some steps of the methodology were supplied by the local agent of Ivoclar Vivadent.