Comparative study of the strength characteristics of a novel wood-plastic composite and commonly used synthetic casting materials

Background: Woodcast® is a wood-plastic composite casting material that becomes pliable and self-adhesive when heated to 65 °C and returns to being weightbearing as it cools down. The present study aims to test whether this novel non-toxic casting material is strong enough for clinical use by comparing its strength against materials that are already used in weightbearing casting applications such as total contact casts. Methods: The strength of Woodcast® samples was compared against the strength of two commonly used synthetic casting materials (Delta-Cast®, OrthoTape). The effect of environmental factors such as cooling, prolonged heating and exposure to water was also assessed. Findings: The results of this study indicated that Woodcast® is stronger than the synthetic casting materials in compression but weaker in tension. The flexural strength of Woodcast® was 14.24 MPa (±1.25 MPa) while the respective strength of Delta-Cast® and OrthoTape was 18.96 MPa (±7.46 MPa) and 12.93 MPa (±1.93 MPa). Independent samples t-test indicated that the difference between Woodcast® and the other two materials was not statistically significant (P > .05). Woodcast® recovered 90% and 78% of its tensile or flexural strength respectively after 15 min of cooling at ambient temperature and its strength was not reduced by prolonged heating. On average, exposure to water reduced the flexural strength of Delta-Cast® by 6% and of OrthoTape by 44%. The strength of Woodcast® was not affected by exposure to water. Interpretation: The comparison between Woodcast® and commonly used synthetic casting materials indicated that Woodcast® is indeed strong enough to be safely used in weightbearing casting applications.