Background/Aim
Contamination of ethylene vinyl acetate (EVA) during mouthguard fabrication can cause delamination. The study evaluated the effects of different EVA surface treatments on the contact angle, laminate bond strength, and elongation capacity.
Materials and Methods
Specimens of two bonded EVA plates were prepared (n = 30). The Shore A hardness of standardized EVA plate specimens was measured before and after thermo‐plasticization. The EVA plates were randomly allocated to one of five different surface treatment groups: no treatment (control); isopropyl alcohol, 100%; chloroform, 99.8%; self‐cure acrylic resin monomer (methacrylate, ethylene glycol dimethacrylate, and chemical initiator—amine type); and ethyl alcohol, 70%. The maximum breaking force and elongation at the site of fracture were recorded using a universal testing machine. The contact angle surface was measured using ImageJ software. Scanning electron microscopy of the EVA surface was performed. The laminate bond strength was obtained by dividing the maximum breaking force by the bonding area between the two EVA plates. The laminate bond strength and maximum elongation data were analyzed by one‐way ANOVA, followed by the Tukey's and the Dunnet test. The failure mode data was analyzed using the chi‐square test (α = .05).
Results
EVA surface treatment significantly influenced the laminate bond strength and maximum elongation (p < .001). The control group had a higher contact angle and significantly lower laminate bond strength and maximum elongation than the other groups (p < .001). The acrylic resin monomer and chloroform‐treated specimens had similar laminate bond strength and maximum elongation. The acrylic resin monomer group had a significantly lower contact angle (p < .001).
Conclusions
All treatments had a significantly higher laminate bond strength and maximum elongation than the control group. The acrylic resin monomer and chloroform groups had a significantly higher laminate bond strength and maximum elongation and the acrylic resin monomer group had a lower contact angle than the other groups. The chloroform should be avoided due its hazardous effects.
Objectives
Curing lights cannot be sterilized and should be covered with an infection control barrier. This study evaluated the effect of barriers when applied correctly and incorrectly on the radiant power (mW), irradiance (mW/cm
2
), emission spectrum (mW/nm), and beam profile from a multi-peak light-curing unit (LCU).
Methods
Five plastic barriers (VALO Grand, Ultradent; TIDIShield, TIDI Products; Disposa-Shield, Dentsply Sirona; Cure Sleeve, Kerr; Stretch and Seal, Betty Crocker) and one latex-based barrier (Curelastic, Steri-Shield) were tested. The radiant power (mW) and emission spectrum (mW/nm) from one multi-peak LCU (VALO Grand, Ultradent) was measured using an integrating sphere. LCU tip internal diameter (mm) was measured, then the tip area and irradiance (mW/cm
2
) were calculated. The beam profiles were measured using a laser beam profiler.
Results
When applied correctly, the plastic barriers reduced the radiant power output by 5–8%, and the latex-based barrier by 16 %. When the plastic seam or barrier opaque face was positioned over the LCU tip, the power output was reduced by 8–11%. When the plastic barriers were wrinkled, the power output was significantly reduced by 14–26%. The wrinkled latex-based barrier reduced by 28 %, and further reduced the violet light. The beam profiles illustrated the importance of correctly barrier use without wrinkles over the tip.
Conclusions
Plastic barriers applied correctly reduced the light output (mW) by 5–8 %. The barriers applied incorrectly significantly reduced the light output by 14–26%. The latex-based barrier wrinkled also reduced the amount of violet light.
Clinical relevance
Infection control curing light barriers should be used to prevent cross-infection between patients. However, they must be applied correctly to reduce their negative effects on the light output
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