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Thinning factors influence on custom-made mouthguards thermoforming
Ichiro Kojima1, Tomotaka Takeda, Kazunori Nakajima
1Department of Sports Dentistry, Tokyo Dental College, Mihama-ku, Chiba, Japan.
Summary
Thermoforming thinning varies by surface angle, with pressure forming causing more reduction on 45 and 90-degree surfaces. Material type and thickness did not significantly impact thinning rates.
Area of Science:
- Materials Science
- Biomaterials Engineering
- Dental Technology
Background:
- Thermoforming is a common technique in fabricating dental appliances, such as mouthguards.
- Understanding material thinning during thermoforming is crucial for ensuring appliance fit and function.
- Previous studies have explored various factors affecting thermoforming, but a detailed analysis of surface angle influence is needed.
Purpose of the Study:
- To quantify the thinning of thermoformed materials at different surface angles (0, 45, and 90 degrees) under pressure and vacuum forming.
- To identify factors influencing thinning, including material type, thickness, color, and forming method.
- To provide data for optimizing mouthguard fabrication and material selection.
Main Methods:
- A simulation model was used to analyze thermoforming of EVA and acrylic resin blanks.
- Samples were subjected to pressure and vacuum forming.
- Thickness measurements were taken using a thickness gauge.
- Thinning rates were calculated for different surface angles and conditions.
Main Results:
- Pressure forming resulted in significantly greater thinning at 45 and 90-degree surfaces (up to 66% at 90 degrees) compared to 0-degree surfaces (2%).
- Vacuum forming showed less thinning (36% at 90 degrees).
- Thinning increased with distance from the center on 0-degree surfaces and decreased with height on vertical surfaces.
- Acrylic resin exhibited approximately 10% less thinning than EVA.
- Air pressure, EVA thickness, and material color did not significantly affect thinning.
Conclusions:
- Surface angle is a critical factor in thermoforming thinning, with steeper angles experiencing more reduction.
- Pressure forming leads to more pronounced thinning, especially on angled surfaces, necessitating careful material selection and lamination strategies.
- For applications like incisal aspects of mouthguards, material lamination (e.g., two 3-mm layers) is recommended to achieve desired final thickness.
- Further consideration for occlusal adjustments is needed in mouthguard fabrication to meet specific thickness requirements.
