ABSTRACT The degree of conversion (DC) of dental resin composites critically determines their mechanical properties and clinical durability. This study elucidates how formulation parameters govern the degree of conversion in Bis‐GMA/TEGDMA/silica composites using photo‐differential scanning calorimetry. This approach provides new insights into the efficiency and kinetics of photocuring in dental composite materials. Increasing the concentration of the camphorquinone/dimethylaminoethyl methacrylate (CQ/DMAEMA) photo‐initiator system from 0.2% to 1.0 wt.% enhanced the DC up to ~70%, beyond which no significant gain was observed. The incorporation of 50 wt.% silica via the sol–gel route delayed the polymerization onset but remained within clinically acceptable limits. The addition of diphenyliodonium hexafluorophosphate (DPIHP) significantly improved polymerization kinetics, reducing the DC plateau time from 40 to 10 s and increasing final conversion to ~64%. The amphiphilic nature of DPIHP enhanced radical generation by bridging hydrophilic and hydrophobic domains. At 10 wt.% water content, CQ/DMAEMA systems showed reduced reactivity due to phase separation, whereas more hydrophobic systems (CQ/4E, CQ/DPIHP) maintained higher DCs values. The presence of water slightly increased monomer mobility, contributing marginally to conversion. These findings highlight the importance of adapting the initiator system and resin formulation to optimize the polymerization performance of dental composites.
Latoui et al. (2026) studied this question.