J Dent Rehabil Appl Sci.  2020 Sep;36(3):183-195. 10.14368/jdras.2020.36.3.183.

Comparison of flexural strength according to thickness between CAD/CAM denture base resins and conventional denture base resins

Affiliations
  • 1Department of Prosthodontics, College of Dentistry, Dankook University, Cheonan, Republic of Korea

Abstract

Purpose
The purpose of this study is to compare the flexural strength of CAD/CAM denture base resins with conventional denture base resins based on their thicknesses.
Materials and Methods
For the conventional denture base resins, Lucitone 199® (C-LC) was used. DIOnavi - Denture (P-DO) and DENTCA Denture Base II (P-DC) were taken for the 3D printing denture base resins. For the prepolymerized PMMA resins, Vipi Block Gum (M-VP) and M-IVoBase® CAD (M-IV) were used. The final dimensions of the specimens were 65.0 mm x 12.7 mm x 1.6 mm / 2.0 mm / 2.5 mm. The 3-point bend test was implemented to measure the flexural strength and flexural modulus. Microscopic evaluation of surface of fractured specimen was conducted by using a scanning electron micro-scope (SEM). After testing the normality of the data, one-way ANOVA was adopted to evaluate the differences among sample groups with a significance level of P = 0.05. The Tukey HSD test was performed for post hoc analysis.
Results
Under the same thicknesses, there are significant differences in flexural strength between CAD/CAM denture base resins and conventional denture base resins except for P-DO and C-LC. M-VP showed higher flexural strength than conventional denture base resins, P-DC and M-IV displayed lower flexural strength than conventional denture base resins. Flexural modulus was highest in M-VP, followed by C-LC, P-DO, P-DC, M-IV, significant differences were found between all materials. In the comparison of flexural strength according to thickness, flexural strength of 2.5 mm was significantly higher than that of 1.6 mm in C-LC. Flexural strength of 2.5 mm and 2.0 mm was significantly higher than that of 1.6 mm in P-DC and M-VP. In M-IV, as the thickness increases, significant increase in flexural strength appeared. SEM analysis illustrates different fracture surfaces of the specimens.
Conclusion
The flexural strength of different CAD/CAM denture base resins used in this study varied according to the composition and properties of each material. The flexural strength of CAD/ CAM denture base resins was higher than the standard suggested by ISO 20795-1:2013 at a thickness of 1.6 mm or more though the thickness decreased. However, for clinical use of dentures with lower thickness, further researches should be done regarding other properties at lower thickness of denture base resins.

Keyword

CAD/CAM denture base resins; pre-polymerized PMMA block; 3D printing denture base resins; flexural strength; thickness
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