Purpose: The objective of this study was to investigate the physical properties of a model dental compound formulated to autonomically heal cracks with biocompatible chemistry. Methods: A visible light cured model resin consisting of TEGMA:UDMA:BisGMA (1:1:1) at 45% w/w with silane 0.7 µm glass was formulated with a self-healing system consisting of encapsulated bisgma and a readical accelerator and encapsulated BPO initiator. The base resin was also formulated with the monomer/accelerator and initiator alone. Fracture toughness (KIc) was assessed using single edge notch specimens (2.5mm (B) x 5 mm (W) x 25 mm; a/w=0.5) in 3-point bend (n=12). Data was analyzed with ANOVA/Tukey's at p ≤ 0.05. Dynamic mechanical analysis (DMA) was performed from -150 ºC to 250 ºC at 1 degree/min and 1 Hz. Storage and loss modulus, glass transition temperature and tangent of delta was recorded for each material.
Results:
Glass Filler Percent | BisGMA/accelerator Microcapsules (wt%) | BPO Microcapsules (wt%) | K1c (MPa x m1/2) |
55 | 1.56 ± 0.13 | ||
55 | 5 | 1.36 ± 0.10 | |
55 | 2 | 1.50 ± 0.11 | |
55 | 5 | 2 | 1.26 ± 0.10 |
The self-healing material was loaded to failure for 24 hours and loaded a second time to failure. These specimens had a KIc of 0.75± 0.21 for a 50% recovery rate or the original fracture toughness in a non-optimized formulation. The modulus and fracture toughness of the self healing material statistically similar (p>0.05) to the control and the tan delta suggests no real loss of the material's ability to absorb energy by damping. Conclusions: The self healing capability of a dental material was explored. Autonomic healing was demonstrated with biocompatible healing chemistry in a model dental composite and DMA data suggest favorable properties compared to a control material.