Castor oil biopolymer used as dental cement: preliminary study

Objectives: The aim of this study was to evaluate the physical-mechanical performance of an experimental polyurethane dental luting agent derived from castor oil (PUCO) with or without the addition of calcium carbonate (CaCO₃). Methods: The flexural strength (FS), diametral tensile strength (DTS) and film thickness (FT) of PUCO were determined and compared with values of zinc phosphate cement. Forty specimens were prepared for each property (n=120) and were divided into 4 groups: PUCO without CaCO₃, PUCO with 10% of CaCO₃, PUCO with 50% of CaCO₃, and zinc phosphate cement (control). The cements were manipulated in accordance with the manufacturers' instructions. For the FS and DTS evaluation, the specimens remained under a constant load at 37^oC and 100% relative humidity of the air for 1h and were stored for 24hs in distilled water at 37^oC. FS (3-point bend test) and DTS were performed in a MTS-810 machine (10kN at 0.5mm/min). For the FT evaluation, the cements were positioned between two glass slabs (2cm²) under 15Kg. The difference between the glass slabs thickness without and with the cements determined the FT. Each property was evaluated with the comparison among the four groups. The data were analyzed by one-way ANOVA and Tukey tests (a=0.05). Results: There were no statistical differences on FS values among PUCO groups (p>0.05), and all of them were higher than the control. In the DTS evaluation, no difference was observed between PUCO without CaCO3 and control (p<0.05). PUCO 10% and PUCO 50% were as strong as control (p>0.05). The values of FT showed that PUCO were thicker than control; control was equal to PUCO 10%, and PUCO 50% had the smallest thickness. Conclusions: The preliminary mechanical and physical comparison between PUCO and zinc phosphate cement showed favorable results for the development of a new product.