A study to investigate and compare the physicomechanical properties of experimental and commercial temporary crown and bridge materials

Objectives To develop two experimental temporary crown and bridge materials with improved physicomechanical properties. Methods Commercial materials: Trim (TR, monomethacrylate, Bosworth) and Quicktemp2 (QT, dimethacrylate, Schottlander). Experimental materials: isobutyl methacrylate/poly(ethyl methacrylate) (IBMA/PEM) and n-butyl methacrylate/PEM (nBMA/PEM), both monomethacrylates. For water absorption/desorption studies rectangular samples (40 mm × 10 mm × 1 mm) of each material were prepared, immersed in deionized water (DW, control) and artificial saliva (AS), and weighed at regular time intervals. %solubility and diffusion coefficients (D) for uptake/loss processes were calculated and compared with theoretical predictions. Polymerization exotherm (cylindrical samples 10 mm × 18 mm) and flexural moduli were measured (three point bending; rectangular samples 80 mm × 10 mm × 4 mm, dry and after 9 days storage in DW). The data were compared statistically. Results QT and nBMA/PEM had lower %equilibrium uptakes/loss in DW (0.68%/0.884% and 0.64%/0.895% respectively). QT had the lowest water absorption/desorption D (P < 0.05) compared to the three monomethacrylates, in DW and AS. %solubility for all systems showed no differences in DW (P > 0.05), but a difference for QT in AS (P < 0.05). QT reached its maximum temperature rapidly (∼2 min; 3 monomethacrylates ∼7-13 min). The commercial materials exhibited high peak temperatures (∼51 °C, P < 0.05; experimental materials ∼43 °C). QT had a higher flexural modulus (∼4 GPa; 3 monomethacrylates ∼0.7-1 GPa) for dry and wet samples. The moduli for commercial materials reduced significantly after immersion in DW; there was no difference between the dry and wet experimental materials samples (P > 0.05). Significance The experimental materials merit further studies since they presented with lower setting exotherms, and contained no phthalate plasticizer, thus being less of a risk to patients.