Ultimate Tensile Strength Evaluation of Bi-Colored Ethylene-Vinyl Acetate (EVA) Sheets In-Office Manufactured With...

Bi-colored mouthguards (MTG) are often sought by both professional and amateur athletes. Bi-colored MTG can be made in the dental office from premanufactured bi-colored EVA sheets or custom-designed in the dental office for greater color variety. This study aimed to evaluate the tensile strength of ethylene-vinyl acetate (EVA) plates from two commercial brands (BioArt and Polyshok), using different bonding methods and heat sources for producing bicolored MTG.

EVA plates from BioArt and Polyshok (3 mm thickness) were bonded using six methods combining two bonding materials (metal angle and glass plate) and three heat sources (heat gun, mini-torch, and Hannau lamp). Bonded plates were sectioned into 30 standardized bar-shaped samples (70 × 10 × 3 mm) and subjected to tensile testing. Ultimate tensile strength was recorded, and statistical analyses were performed using One-Way ANOVA and Tukey's test (α = 0.05).

Significant differences in ultimate tensile strength (MPa) were observed between bonding methods (p < 0.001) for each commercial brand. The metal angle and heat gun (MAH) method exhibited the highest tensile strength for both tested EVAs (BioArt: 146.5 ± 30 MPa; Polyshok: 87.8 ± 19.3 MPa). The Hannau lamp produced the lowest values for both tested EVAs (BioArt: 69.8 ± 43.1 MPa; Polyshok: 51.0 ± 14.4 MPa).

The bonding method significantly affects the tensile strength of EVA plates, with the MAH method and heat gun demonstrating superior performance. These findings highlight the importance of optimizing bonding techniques to ensure durability and protective performance in bi-colored MTG.