Comparison of ISO and ASTM standards in determining the flexural strength of denture base resin

Abstract

Purpose: The aim of this study was to compare the differences between the ASTM D790 and ISO 20795.1.2013 standards in evaluating the flexural strength of heat cure poly methyl methacrylate (PMMA) denture base resin. Materials and Methods: 30 heat cure denture base samples were fabricated in accordance to ISO 20795.1.2013 and ASTM D790 Standards. The specimens were finished and stored following the standardized protocol. The flexural strength was determined using universal testing machine at cross head speed of 1.50 mm/min and a span length of 40.00 mm. The mean flexural strength values were calculated in megapascals (MPa), and statistically analyzed. Results: The mean flexural strength of heat cure PMMA found with ISO and ASTM ranged between 60.492 MPa and 61.470 MPa. There was no significant difference between the two methods. Conclusion: The quantitative differences existed in the flexural strength of denture base resin between ISO 20795.1.2013and ASTM 790 protocols but those differences had no statistical and clinical significance.

Keywords

• ISO
• ASTM
• denture base
• poly methyl methacrylate
• resin

References

1. 1. Chander NG. Polymethyl metha acrylate denture base. An overview. J Indian Prosthodont Soc 2018; 18:87-8.
2. 2. Gad MM, Fouda SM, Al-Harbi FA, Näpänkangas R, Raustia A. PMMA denture base material enhancement: a review of fiber, filler, and nanofiller addition. Int J Nanomedicine 2017;12:3801-1.
3. 3. Chitchumnong P, Brooks SC, Stafford GD. Comparison of three- and four-point flexural strength testing of denture-base polymers. Dent Mater 1989; 5:2-5.
4. 4. Sweeney WW, Caul HJ, Genug W.A. Transverse Testing Machine for Denture Resins, J Am Dent Assoc 1954. 49: 174- 6.
5. 5. Osborne J .Transverse Tests on Denture Base Materials, Br Dent J 1949. 86: 64-67.
6. 6. Souder W , and Paffenbarger GC .Physical Properties of Dental Materials, Circular C433, National Bureau of Standards, Washington, DC.US Government Printing Office, 1942;. 173.
7. 7. Stafford GD, Bates JF, Huggett R and Handley RW. A Review of the Properties of Some Denture Base Polymers. Br Dent J 1980. 8: 292-306.
8. 8. International Organization for Standardization. ISO 20795- 1: 2013. Dentistry – Base polymers- Part 1: Denture base polymers. Geneva: ISO; 2013:1-42.

9. 9. American Society for Testing and Materials. ASTM Standard D 790-02. Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials. ASTM International, West Conshohocken, United States.ASTM; 2002.146-54.
10. 10. Jagger DC, Harrison A, Jandt KD. The reinforcement of dentures. J Oral Rehabil 1999 Mar; 26:185-94.
11. 11. Vallittu PK. A review of fiber-reinforced denture base resins. J Prosthodont 1996; 5:270-6.
12. 12. Somkuwar S, Mishra SK, Agrawal B, Choure R. Comparison of the flexural strength of polymethyl methacrylate resin reinforced with multiwalled carbon nanotubes and processed by conventional water bath technique and microwave polymerization. J Indian Prosthodont Soc 2017; 17:332-9.
13. 13. Ucar Y, Akova T, Aysan I. Mechanical properties of polyamide versus different PMMA denture base materials. J Prosthodont 2012;21:173-6.
14. 14. Harini P, Mohamed K, Padmanabhan TV. Effect of Titanium dioxide nanoparticles on the flexural strength of polymethylmethacrylate: an in vitro study. Indian J Dent Res 2014;25:459-63
15. 15. Venkat R, Gopichander N, Vasantakumar M. Comprehensive analysis of repair/reinforcement materials for polymethyl methacrylate denture bases: mechanical and dimensional stability characteristics. J Indian Prosthodont Soc 2013; 13:439-49.
16. 16. Phoenix RD, Mansueto MA, Ackerman NA, Jones RE. Evaluation of mechanical and thermal properties of commonly used denture base resins. J Prosthodont 2004;13:17-27