The Effect of Thermoforming on Tear Strength of Ethylene Vinyl Acetate Mouthguard Material in Various Thicknesses

Abstract:

The effect of thermoforming on the tear strength of ethylene vinyl acetate (EVA) mouthguard material (Bioplast^®) has not been widely investigated. The present study compared the tear strengths of non-processed and processed EVA specimens in various thicknesses. Two groups of EVA sheet (non-processed and processed) in three different thicknesses of 3, 4 and 5 mm were used in specimen fabrication. The processed EVA sheets were achieved by forming the EVA sheet on the cylindrical stone model with the pressure-molding device (Biostar^®). Twelve of tear strength specimens of non-processed and processed group in each thickness were prepared following the modified ASTM D 624-00 guideline. The tear strength test was conducted using universal testing machine (Lloyd^® 1K series) with the speed of 500 mm/min. The mean thickness and tear strength of the non-processed and processed specimens in each thickness were compared using independent T-test. The differences in the mean tear strength for each thickness of non-processed and process specimens were determined using one-way ANOVA. The mean tear strength and mean thickness of processed EVA specimens was significantly lower than the non-processed EVA specimens for every thickness (P ≤ 0.05). There was no significant difference in the mean tear strength of EVA specimens among each thickness in both non-processed and processed groups. It can be concluded that the thermoforming process has the significant effect on the tear strength of the EVA mouthguard material formed by pressure molding device in every thicknesses. The tear strength of processed specimens were significant lower than the non-processed. Thus, it is more relevant for testing properties of the processed mouthguard material that the mouthguard material before processing.

• Periodical: Key Engineering Materials (Volume 751)
• Pages: 657-662
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.751.657
• Online since: August 2017
• Authors: Phakphum Srinuan*, Jeerapatr O. Baiyokvichit, Rasana Boonpeng, Tanapol Wongwisatekit, Pacharaporn Pattanasukwasan, Irada Karnjanangulpan
• Keywords: Ethylene Vinyl Acetate, Mouthguard, Tear Strength, Thermoforming

References

[1] The Glossary of Prosthodontic Terms. Journal of Prosthetic Dentistry. 94(1): pp.10-92.

[2] Knapik, J.J., et al., Mouthguards in Sport Activities History, Physical Properties and Injury Prevention Effectiveness. Sports Medicine, 2013. 37(2): pp.117-144.

DOI: 10.2165/00007256-200737020-00003

[3] Guevara, P. and D. Ranalli, Techniques for mouthguard fabrication. Dental Clinics of North America, 1991. 35(4): pp.667-682.

DOI: 10.1016/s0011-8532(22)00833-3

[4] Newsome, P., D. Tran, and M. Cooke, The role of the mouthguard in the prevention of sports‐related dental injuries: a review. International Journal of Paediatric Dentistry, 2001. 11(6): pp.396-404.

DOI: 10.1046/j.0960-7439.2001.00304.x

[5] Maeda, Y., et al., Effectiveness and fabrication of mouthguards. Dental Traumatology, 2009. 25(6): pp.556-564.

DOI: 10.1111/j.1600-9657.2009.00822.x

[6] Choy, M., A comparison of custom-made mouthguards. Hawaii dental journal, 1998. 29(3): pp.28-28.

[7] Mizuhashi, F., K. Koide, and M. Takahashi, Variations in mouthguard thickness according to fabrication method. Dental Traumatology, 2015. 31(2): pp.130-135.

DOI: 10.1111/edt.12128

[8] Knapik, J.J., et al., Mouthguards in sport activities history, physical properties and injury prevention effectiveness. Sports Medicine, 2007. 37(2): pp.117-144.

DOI: 10.2165/00007256-200737020-00003

[9] Jagger, R., P. Milward, and M. Waters, Properties of an experimental mouthguard material. International Journal of Prosthodontics, 2000. 13(5).

[10] Bishop, B., E. Davies, and J. Von Fraunhofer, Materials for mouth protectors. The Journal of prosthetic dentistry, 1985. 53(2): pp.256-261.

DOI: 10.1016/0022-3913(85)90123-4

[11] Gould, T.E., et al., Characterization of mouthguard materials: physical and mechanical properties of commercialized products. Dental materials, 2009. 25(6): pp.771-780.

DOI: 10.1016/j.dental.2008.12.005

[12] Craig, R. and W. Godwin, Properties of athletic mouth protectors and materials. Journal of oral rehabilitation, 2002. 29(2): pp.146-150.

DOI: 10.1046/j.1365-2842.2002.00831.x

[13] ASTM D D624-00 2003(2012), Standard Test Method for Tear Strength of Conventional Vulcanized Rubber and Thermoplastic Elastomers, ASTM International: West Conshohocken, PA. (2012).

DOI: 10.1520/d0624-00

[14] Anusavice, K.J., C. Shen, and H.R. Rawls, Phillips' science of dental materials. 2013: Elsevier Health Sciences.

[15] Patrick, D. G., van Noort, R., & Found, M. S. (2006). The influence of heat treatment on the impact performance of sports mouthguard materials. Composites Part A: Applied Science and Manufacturing, 37(9), 1423-1427.

DOI: 10.1016/j.compositesa.2005.06.015

[16] Geary, J. L., & Kinirons, M. J. (2008). Post thermoforming dimensional changes of ethylene vinyl acetate used in custom‐made mouthguards for trauma prevention–a pilot study. Dental Traumatology, 24(3), 350-355.

DOI: 10.1111/j.1600-9657.2007.00550.x

[17] Westerman, B., Stringfellow, P., & Eccleston, J. (1995). Forces transmitted through EVA mouthguard materials of different types and thickness. Australian dental journal, 40(6), 389-391.

DOI: 10.1111/j.1834-7819.1995.tb04838.x

[18] Mizuhashi, F., et al., A method to maintain the thickness of the mouthguard after the vacuum forming process: changes of the holding conditions of the mouthguard sheet. Dental Traumatology, 2012. 28(4): pp.291-295.

DOI: 10.1111/j.1600-9657.2011.01091.x

[19] Mizuhashi, F., K. Koide, and M. Takahashi, Thickness and fit of mouthguards according to a vacuum‐forming process. Dental Traumatology, 2013. 29(4): pp.307-312.

DOI: 10.1111/edt.12004

[20] Mizuhashi, F., K. Koide, and M. Takahashi, Thickness and fit of mouthguards adjusted by notching thermoplastic sheets under different heating conditions. Dental Traumatology, 2015. 31(4): pp.288-293.

DOI: 10.1111/edt.12143