Comparison of flexural strength, monomer release and wear properties of occlusal splint materials
Dr. Nurul Liyana Binti Aminuddin, Prof. Haralampos Petridis
Eastman Dental Institute
Objectives
The aim of this in vitro study was to evaluate the flexural strength, monomer release and wear resistance between conventional PMMA, milled PMMA and 3D-printed resin built in different printing angles (0° and 30°) for occlusal splint fabrication.
Materials and Methods
Four occlusal splint materials were evaluated using three manufacturing methods. One conventional heat-cured PMMA (Oracryl), one milled PMMA (Kerox Premia) and two different brands of 3D-printed resins (FreePrint Splint 2.0 and KeySplint Hard) built in two different printing angles (0° and 30°).
The specimens for flexural strength and wear test were immersed in 37°C water for 50 hours (baseline) and subjected to thermal aging by using a thermocycler for 20,000 cycles with an immersion time of 30 seconds in 5°C/55°C water and a dwell time of 10 seconds before being further tested. The flexural strength, monomer release and wear resistance were statistically analyzed.
Results
The flexural strength, monomer release and wear resistance values were statistically significant among the investigated materials (p<0.05).
Flexural strength was found the highest in milled PMMA (182.8MPa ± 8.5) and the lowest in 0° 3D-printed resin (KeySplint) (73.204MPa ± 14.4).
Milled PMMA was found to release significantly less monomer (7.6ppm ± 3.7) compared to the other groups.
The lowest wear depth was found in milled PMMA (2.8mm3 ± 1.4), indicating the highest wear resistance than the other materials. Meanwhile, the highest volume loss was found in 0° 3D-printed resin (FreePrint).
Conclusions
The milled PMMA splint was recommended to be used for bruxism and long-term application, such as a post-operative Michigan splint due to its high flexural strength, high wear resistance and good biocompatibility. Meanwhile, the 30° 3D-printed resins had better flexural strength and wear resistance compared to the 0° 3D-printed resins. Even though the 3D printed occlusal splint had low flexural strength and wear resistance, thus the 30° 3D printed occlusal splint was suitable for short-term application only, clinically for a few months.