IADR Abstract Archives
Self-Adhesive Composites and Their Viscosity: Insights of the Adhesive Interface
Objectives: To evaluate and compare the interfacial interdiffusion zone formation, of self-adhesive composites made with different functional monomers and viscosities, using micro-Raman spectroscopy.
Methods: Nine experimental self-adhesive composites were formulated, with a base mixture of urethane dimethacrylate (UDMA) and propylene glycol dimethacrylate (PPGDMA) and 15 mol% of a functional monomer (either 2-hydroxyethyl methacrylate, HEMA; glycerolphosphate dimethacrylate, GPDM or 10-methacryloyloxydecyl dihydrogen phosphate, 10-MDP). The powder phase comprised hybrid barium glass/silica particles. In order to vary the viscosity of the composites, three powder-liquid ratios were tested (1.9, 2.2 and 2.5). Composites were made using a centrifugal speed mixer (45 s, 1500 rpm). For the spectroscopic study, 27 sound human molars were sectioned by the middle dentin, polished (600 SiC) and restored (n=3) with 2 mm of each composite, light-cured at 20 s (LCU DB686; COXO Medical Instrument Co., Guangzhou, China). After 24 h storage in water, they were sectioned to expose the adhesive interface. The dentin-composite interfaces were analyzed by mapping a 15 x 15 µm surface area between 800 – 1750 cm-1 (resolution 2 cm-1; 50x). Data analysis included the creation of intensity scale maps, based on characteristic peaks and the measurement of the interdiffusion zone, using a Boltzmann fit.
Results: Qualitative analysis of the spectroscopic images revealed that the formulations with 10-MDP contributed to the formation of an interdiffusion zone, irrespective of the powder-liquid ratio. This was verified to contrast with other monomers, which showed poor diffusion, dependent upon the viscosity.
Conclusions: The quality and width of the interdiffusion zone seems to be influenced by the adhesive monomer, while the powder-liquid ratios tested were not a major contributing factor.
Methods: Nine experimental self-adhesive composites were formulated, with a base mixture of urethane dimethacrylate (UDMA) and propylene glycol dimethacrylate (PPGDMA) and 15 mol% of a functional monomer (either 2-hydroxyethyl methacrylate, HEMA; glycerolphosphate dimethacrylate, GPDM or 10-methacryloyloxydecyl dihydrogen phosphate, 10-MDP). The powder phase comprised hybrid barium glass/silica particles. In order to vary the viscosity of the composites, three powder-liquid ratios were tested (1.9, 2.2 and 2.5). Composites were made using a centrifugal speed mixer (45 s, 1500 rpm). For the spectroscopic study, 27 sound human molars were sectioned by the middle dentin, polished (600 SiC) and restored (n=3) with 2 mm of each composite, light-cured at 20 s (LCU DB686; COXO Medical Instrument Co., Guangzhou, China). After 24 h storage in water, they were sectioned to expose the adhesive interface. The dentin-composite interfaces were analyzed by mapping a 15 x 15 µm surface area between 800 – 1750 cm-1 (resolution 2 cm-1; 50x). Data analysis included the creation of intensity scale maps, based on characteristic peaks and the measurement of the interdiffusion zone, using a Boltzmann fit.
Results: Qualitative analysis of the spectroscopic images revealed that the formulations with 10-MDP contributed to the formation of an interdiffusion zone, irrespective of the powder-liquid ratio. This was verified to contrast with other monomers, which showed poor diffusion, dependent upon the viscosity.
Conclusions: The quality and width of the interdiffusion zone seems to be influenced by the adhesive monomer, while the powder-liquid ratios tested were not a major contributing factor.