The polymerizable α-keto ester methacryloylethyl phenylglyoxylate (MEPG), and its homopolymer, were synthesized and tested for their photoinitiation capabilities in a crosslinking monomer resin system containing bis-phenol A-glycidyl methacrylate (BisGMA) and triethylene glycol dimethacrylate (TEGDMA). Monomer conversion kinetic data were collected using both the MEPG and poly(MEPG) as initiator and/or comonomer. Furthermore, the evolution of CO resulting from the photoinduced decarbonylation led to a significant reduction in the volume shrinkage of the resin upon photocuring with a UV light. The shrinkage of the resin was reduced by 63% when 45% of MEPG was added to the BisGMA/TEGDMA monomer mixture of the resin. However, dispersion of the CO voids was uncontrolled, resulting in large voids which are likely to be detrimental to material properties. Addition of inorganic filler (SiO₂) to the resin mixture did not affect CO generation and produced even less shrinkage compared to systems without SiO₂ at given MEPG concentrations.