Force Measurement During Dental Cutting Procedures for Resin Characterisation

Objectives: This study set out to develop a method to characterise the cutting forces applied during dental procedures using an electric handpiece and to aid the development of novel 3D printable resin formulations that mimic the cutting characteristics of human teeth for training purposes.
Methods: Cylinders (diameter 3mm, height 8mm) of commercially available (Filtek Supreme, 3M) and novel resin formulations (BisGMA/TEGDMA; 70:30 – 30:70 wt%; 0.42wt% TPO) which varied by viscosity, and filler load (0-50 vol%). Extracted teeth were used a control - obtained with ethical approval (BCHCDent048.2024). Specimens were painted black and randomised. Specimens (n=10) were mounted onto a static load cell (Instron, 100N, 45804) connected to a Universal Testing Machine (Instron 5544, Works US). An NSK Ti-Max Z95L handpiece (NSK, Japan) was run at 200,000rpm using a NSK Surgic XT Plus motor (NSK, Japan). A 3mm vertical cut was made using a diamond 3mm fissure bur (Henry Schein, US). The force (N) applied during cutting was recorded in real time . The area under time/force curve (energy to cut), force used in the loading phase and time were analysed. Multivariate analysis of variance (ANOVA) and post hoc Tukey comparisons (p<0.05) were used to assess the interactions between materials.
Results: Two-way ANOVA confirmed differences in material characteristics (p<0.05). Statistically significant difference was apparent in the amount of force and time required to cut resin and extracted teeth and between resin formulations (enamel and dentine required 6.2J (+/-1.7) to cut in comparison to BisEMA/TegDMA (60:40) which required 2.94 (+/-0.80)).
Conclusions: The development of a reliable method is a useful tool to understand the cutting characteristics of dental tissues and materials. Such information may aid the development of materials that have realistic feedback to mimic natural tissues for educational use.