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 different combinations of self healing additives. Formulations that included 1-7 weight percent microcapsules of UDMA or TEGMA mixed with an accelerator were incorporated into the base formulation. Microcapsules containing the radical initiator that was prepared under 3 different synthetic conditions were incorporated into the base formulation. Fracture toughness (KIc) was assessed using single edge notch specimens 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, Tg and tan delta was recorded for each material. Wear measurements were performed on controls and formulations containing the self healing additives. Results: Statistical analysis revealed differences in the ten different sets of formulations prepared and studied by fracture toughness and dynamic mechanical analysis. A table highlighting some of the results is shown below.
Microcapsule Content | Weight % of Microcapsule | E' 109 | E” 108 | Tg (°C) | Tan Delta |
None/Control | 0 | 3.2 | 2.0 | 119 | 0.204 |
TEGMA | 1 | 4.3 | 2.5 | 120 | 0.187 |
TEGMA | 3 | 4.1 | 2.2 | 124 | 0.187 |
TEGMA | 5 | 3.8 | 2.3 | 121 | 0.183 |
TEGMA | 7 | 2.6 | 1.4 | 122 | 0.180 |
UDMA | 3 | 5.6 | 2.5 | 135 | 0.190 |
Conclusions: The physical properties of self healing dental formulations have been characterized by fracture toughness, DMA and wear. The type of monomer encapsulated, additive preparation conditions and the amount of each additive affect the overall physical properties of the composite formulation. This work is funded in part by an NSF EPSCOR University-Industry Partnership grant and GL Materials, LLC.