부산대학교 도서관

This thesis explores points for potential development in a class of dental restorative materials known as photo-activated resin-based composites (RBC). Dental RBCs based on dimethacrylate chemistry are increasingly used in contemporary dental practice due, in part, to a phasing-out of mercury-amalgam alternatives. However, improved clinical longevity of dental RBCs is required and a broad range of approaches to achieve this have been suggested. It was proposed that there is an inadequate understanding of the formation of the polymer network in dental RBCs at an interparticulate length-scale preventing optimisation of matrix formulation and photo-curing. In addition, it was hypothesised that the polymer network can be mechanically reinforced by the introduction of organic nanofiller which can additionally be functionalised to provide antimicrobial properties. Results demonstrated the spatial heterogeneity in reactive group conversion in experimental micro-filled RBCs at interparticulate length scales, and how this evolves with time, following cessation of photo-curing. Subsequently it was demonstrated how the presence of conventional nano-fillers and a new organic nano-sized filler (ONF) effects matrix polymerisation. The feasibility of incorporating the ONFs into dimethacrylate resin matrices was studied. Significantly improved ONF dispersion was achieved by incorporation using a solvent exchange (SE) process, which also led to mild mechanical reinforcement in short-term studies. Functionalisation of the ONF with antimicrobial compounds was achieved conferring antibacterial activity to the resultant RBCs. Simulation of longer-term behaviour, including water storage and fatigue testing showed that ONFs and functionalised ONFs significantly increased water sorption and reduced the flexural fatigue limit. Nano-hybrid RBCs containing both micro-fillers and ONFs were fabricated, and exhibited flexural strength, flexural modulus, and optical properties within an acceptable range for future RBC development.