Abstract
The objective of this study was to evaluate the physicomechanical properties of a series of polyhedral silsesquioxane (SSQ) methacrylate monomers developed for dental applications. The effect of chain modifications on the properties of the SSQโbased monomers was also evaluated. Physicomechanical properties that are investigated include polymerization shrinkage, degree of conversion, hardness, and modulus. Results obtained were compared with unfilled 1:1 (control) bisโGMA/TEGDMA materials (typical monomers used in dental composites). All samples investigated were cured using 400โ500 nm light at 500 mW/cm^2^ for 40 s. Shrinkage associated with curing and postโgel reactions for all synthesized SSQ compounds were found to range from (0.04 ยฑ 0.01)% to (0.33 ยฑ 0.03)% with degree of conversion ranging from (56.68 ยฑ 2.81)% to (84.53 ยฑ 2.62)%. At all time intervals, postโgel shrinkage associated with control was found to be significantly greater than all SSQ compounds. No significant difference in degree of conversion was observed for control, and all SSQ compounds except for SSQ attached with eight equivalents of shortโchain methacrylate. Mechanical properties associated with SSQ compounds were found to be significantly lower than control. However, through chain modifications, mechanical properties of SSQ compounds can be improved by โผ50%. ยฉ 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008