Pilot in-vitro study on insertion/removal performance of hand-cast, milled and 3D printed splints

Area of Science:

• Biomaterials Science
• Dental Materials
• Mechanical Engineering

Background:

• Dental splints are crucial for managing various oral conditions.
• Evaluating the durability and performance of different splint fabrication methods is essential for clinical success.
• Existing testing methods may not fully capture real-world insertion and removal stresses.

Purpose of the Study:

• To establish a novel in-vitro testing method for evaluating dental splint insertion and removal performance.
• To compare the cyclic insertion/removal performance of dental splints fabricated using different manufacturing techniques.
• To identify which splint materials and fabrication methods offer superior durability.

Main Methods:

• Manufactured 56 lower jaw splints from five groups: hand-cast methacrylate, deep-drawn Polyethyleneterephthalate, combined deep-draw methacrylate, CAD/CAM-milled methacrylate, and 3D-printed methacrylate.
• Subjected splints to 10 days of water storage at 37°C.
• Assessed cyclic pull-off and insertion performance on a standardized metal jaw model, analyzing failure modes with finite element analysis.

Main Results:

• Significant differences (p=0.000) in insertion/pull-off cycles were observed, ranging from 864 (MA) to 202,640 (Deep Draw MA).
• Splint fractures predominantly occurred in specific regions (31-34 and 35), with 44 of 56 splints fracturing.
• Finite element analysis corroborated the observed fracture patterns and locations.

Conclusions:

• Deep-draw, cast methacrylate, and combined systems demonstrated superior insertion/pull-off performance compared to printed or milled splints.
• The processing method significantly influences the insertion/pull-off performance of dental splints.
• The developed in-vitro test effectively estimates the clinical performance of dental splints.