engleski

Effect of inert fillers on ion release from ACP composites

Objectives: Amorphous calcium phosphate (ACP) polymeric composites can regenerate mineral-deficient tooth structures due to their release of remineralizing calcium and phosphate ions and re-precipitation of apatite. Their mechanical properties are customarily improved by adding inert fillers. This study evaluates the effect(s) of several inert fillers on the kinetics of ion release from ACP composites. Methods: Eight ACP composites were tested: two controls containing only ACP (40%) and the experimental hydrophilic resin (60%) and six composites containing 40% ACP, 5% or 10% filler (silanized silica (12µm), silanized barium (0.7µm) or strontium glass (1µm) and 55% or 50% resin. Composite disk specimens (20/group) were light-cured for 80s (intensity: 1090mW/cm2) and immersed in buffered saline solution (pH=7.4 ; 37oC). Solution calcium and phosphate concentrations were determined with Inductively Coupled Plasma-Atomic Emission Spectroscopy at 1, 7, 14 and 28 days of immersion (static system) or after replacing the immersing medium with fresh saline solution at days 2, 8 and 15 (dynamic system). Statistical analysis was performed using Mann-Whitney test (a=0.05). Results: At 28 days in dynamic system, no statistical difference existed between the materials with added 10% strontium (Ca=8.03e-3mmol, P=6.37e-3mmol) or 10% barium glass (Ca=10.5e-3mmol, P=8.36e-3mmol) and corresponding ACP control (Ca=10.0e-3mmol, P=8.63e-3mmol). However, silica-containing ACP composites (ACP+5% silica-Ca=8.76e-3mmol, P=9.49e-3mmol ; ACP+10% silica-Ca=8.63e-3mmol, P=9.16e-3mmol) exhibited statistically higher ion release than the control (Ca=6.73e-3mmol, P=7.53e-3mmol). At 28 days, the dynamic values were statistically higher than the corresponding static values for each material, except for ACP+5% strontium glass. In both static and dynamic system, the attained solution supersaturations were conducive for hydroxyapatite formation. Conclusions: Addition of strontium and barium glass does not influence the ion release, while silica fillers improve calcium and phosphate release from the experimental ACP composites. This study was supported by MZOS (065-0352851-0410), The National Foundation for Science, Higher Education and Technological Development (Croatia), Forschungsgemeinschaft Dental and NIDCR (DE13169).

amorphous calcium phosphate; composite resins; ion release

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