Objectives: This study aimed to synthesize and investigate the post-gel polymerization shrinkage of novel POSS (Polyhedral Oligomeric Silsesquioxane) based polymers for dental restorations. Methods: Two polymeric resins MA-POSS and ME-POSS with methacrylate and or epoxy functionalities were synthesized by reacting allyl ether methacrylate and or vinyl cyclohexene epoxide with polyhedral octahydridosilsesquioxanes in stoichiometric amounts directly at elevated temperature. Polymerization shrinkage were then investigated and compared with unfilled 1:1 (control) and 1:2 Bis-GMA / TEGDMA polymers. All samples investigated were polymerized at 500 mW/cm2 for 40 seconds using a light-cure unit (BISCO VIP) that allowed for independent command over time and intensity. A strain-monitoring device and test configuration was used to measure the linear polymerization shrinkage of all polymers during and post light polymerization up to 60 minutes. Three specimens were made for each polymer. Results obtained were converted to volumetric shrinkage and analyzed using ANOVA/Scheffe's post-hoc test at significance level 0.05. Results: Volumetric shrinkage for the unfilled Bis-GMA/ TEGDMA polymeric resins and newly synthesized polymeric resins (MA-POSS/ ME-POSS) were found to range from (0.80 ± 0.08) to (0.96 ± 0.01) % and (-0.34 ± 0.16) to (0.33 ± 0.05) % respectively. Shrinkage associated with unfilled Bis-GMA/ TEGDMA resins was found to be significantly higher than MA-POSS and ME-POSS immediately after light polymerization and at 1, 10, 30 and 60 minutes post light polymerization. At all time intervals, post-gel shrinkage associated with MA-POSS was found to be significantly higher than ME-POSS. Slight volumetric expansion was observed with ME-POSS. Conclusion: Hence, POSS based polymers showed potential for use as dental restorations and represents an optimistic preliminary attempt towards novel low/ non–shrinking dental materials.