Influence of the treatments for ethylene-vinyl acetate on delamination of custom-fitted mouthguard

Abstract

Background/Aims: The contamination on the ethylene vinyl acetate (EVA) during the mouthguard fabrication can generate the delamination. The EVA treatment are not well stablished. The aim was to evaluate the effect of different EVA surface treatment on the contact angle, laminated bond strength and elongation capacity. Materials and Methods: EVA plates (Biaort) were characterized measuring the thickness (mm) using digital caliper, and the Shore A in 3 different locations before and after thermo-plasticization. The EVA plates were randomized in pars and received 5 different surface treatment protocols: NoT, No treatment (Control); IsoAc, Isopropyl Alcohol; Chlo, Chloroform; AcRm, Acrylic resin monomer; 70Alc, 70% Alcohol. The bonding plate area was standardized and after plasticization the specimens were made and tested according to ISO 37-2017 (n = 30). The maximum breaking force (N) and maximal elongation (ME, mm) were recorded at the specimen rupture using universal test machine (Instron E3000). The laminated bond strength (LBS, MPa) was obtained dividing the maximal maximum breaking force (N) by bonding area (mm2 ). The failure modes were classified regarding the rupture location in 5 levels. The contact angle surface was measured using ImageJ software. The LNS and ME data were analyzed by one-way ANOVA followed by Tukey’s test and Dunnet test. The failure mode data was analyzed by Chi-square test ( = 0.05). Results: The EVA surface treatment influenced significantly the LBS and ME (P < 0.001). The control group showed higher CAN and significantly lower LBS and ME than all 9 tested EVA surface treatment (P < 0.001). The AcRm and Chlo had similar LBS, ME and CAN values and higher than other protocols (P <0.001). Failure modes were not influenced by the EVA surface treatment (P = 0.604). Conclusions: All tested protocols resulted in higher LBS and tended to increase the ME of the EVA than control group. The acrylic resin monomer and chloroform surface treatments resulted in lower EVA CAN and higher LBS and ME than other tested protocols.