Shape change in mouthguard sheets during thermoforming.

Area of Science:

• Materials Science
• Biomaterials Engineering
• Dental Technology

Background:

• Thermoforming is key in fabricating dental devices like mouthguards.
• Understanding sheet behavior during heating and forming is essential for product quality.

Purpose of the Study:

• To analyze shape alterations in ethylene vinyl acetate sheets during thermoforming.
• To determine how model positioning affects mouthguard thickness post-fabrication.

Main Methods:

• Sheets with cross-stripes were heated to specific sagging points (15mm and 20mm) in vacuum and pressure forming machines.
• Sheet area changes were calculated using Bretschneider's formula.
• Mouthguard thickness was measured at incisal and molar regions based on model position (anterior-centered vs. centered).

Main Results:

• Higher heating levels (20mm sag) resulted in greater sheet area expansion.
• Area increase was largely concentric, with minimal difference (approx. 5%) between central and peripheral regions.
• Model positioning did not significantly impact final mouthguard thickness.

Conclusions:

• Thermoformed sheet deformation is generally uniform and concentric.
• Optimal model centering is vital for predictable outcomes in mouthguard fabrication.