# Accuracy Comparison among 3D-Printing Technologies to Produce Dental Models
## 4 Discussion
Compared with conventional stone casts, 3D-printed models have been described to be equally accurate [3]. Although this could not be assessed herein, it is noteworthy that the advantages of 3D-printing over conventional methods are not limited to accuracy, but also includes faster procedures and better communication with professionals such as the dental technologist [18]. On the other hand, dental professionals should be aware and have knowledge on the correct usage and disposal procedures of light-cured resins. Professionals should work in well-ventilated areas and use protective gloves. Post-cure using UV light is usually recommended by the manufacturer. Such a procedure should follow proper wash before the printed object is handled without gloves. To wash the 3D-printed before post-curing with a UV light chamber, the professional should use a manufacturer's recommended solvent, such as isopropyl or rubbing alcohol. Alterations in post-processing procedures could also affect the results of 3D-printing trueness and precision, and therefore the procedure should be as standardized as possible. To standardize the 3D-printing methods used herein, all measurements were conducted right after post-processing procedures. Storing 3D-printed objects and light-curing resins also should be performed properly. Professionals should keep UV curable resins sealed tightly in their containers, out of direct sunlight and within a temperature range as suggested by the manufacturer. Differences in precision and accuracy between 3D printers and 3D-printing technologies have also been reported [3]. This finding is in agreement with the present study, insofar as significant pairwise differences were detected by statistical analysis. One of the limitations of this in vitro study performed solely on dental models is that the impact of clinical factors commonly encountered in CBCT exams, such as low resolution of the 3D image reconstruction, could not be addressed. Furthermore, other variables that could affect 3D-printing outcomes such as orientation in the printing bed, different resin types, and shape of the object to be printed were not compared herein. Therefore, future observational clinical studies could address the impact of different CAM systems and materials on trueness, 3D deviation, and precision of dental models. The current fast technological development also requires ongoing research projects to test not only trueness and precision, but also time, cost, and production rates of new 3D printers. In conclusion, the present findings suggest that the 3D-printing methods may have small significant discrepancies when compared to the original digital files, which may not be clinically relevant. Pairwise comparison showed only two significant differences between the cheapest 3D printer (Anycubic Photon) and two high-end 3D-printers (Objet30, Stratasys, \(p=0.025\); and Form 2, Formlabs, \(p=0.048\)). In addition, there were no significant discrepancies among median measurements of each printing method (within 3D printer analysis), which suggests that, for dental casts, all 3D printers analyzed performed similarly. **Author Contributions:** Conceptualization, A.R.G.C. ; methodology, J.H.K., O.H.P.-B., A.P.A., R.L.B.d.S., J.F.L., G.S.U., J.N.-C., M.T.V. and A.R.G.C. ; formal analysis, J.H.K., O.H.P.-B., A.R.G.C. and J.N.-C.; investigation, A.P.A., R.L.B.d.S., J.F.L. and A.R.G.C. ; resources, O.H.P.-B., G.S.U., J.N.-C. and M.T.V. ; data curation, J.H.K., A.P.A. and J.N.-C.; writing--original draft preparation, J.H.K., R.L.B.d.S. and A.R.G.C. ; writing--review and editing, J.H.K., O.H.P.-B., A.P.A., R.L.B.d.S., J.F.L., G.S.U., J.N.-C., M.T.V. and A.R.G.C. ; visualization, J.H.K., A.R.G.C. and J.N.-C.; supervision, A.R.G.C. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable. **Data Availability Statement:** Data is contained within the article.