engleski

Influence of innert fillers on flexure strength of ACP containing composite resins

Aim: Adding amorphous calcium phosphate (ACP), the direct precursor of hydroxylapatite, to composite monomers results in a material which releases calcium and phosphate ions in aqueous environment with the potential of remineralizing carious lesions. However, ACP has no reinforcing capacity needed for the adequate mechanical strength of the material to be used for tooth restoration. The aim of the study was to determine if adding non-releasing fillers to the ACP containing material would improve flexural strength. Materials and methods: Nine materials were subjected to three point flexural test according to ISO 4049, including ACP composite material without added fillers (40% ACP, 60% resins) and six ACP containing materials (all with 40% ACP) with added 5% or 10% of different fillers on the expense of the resin content (55% or 50%). The silanized silica fillers (12μm) (Aerosil DT, Evonik Degussa, Germany) and silanized barium (0.7μm) or strontium glass fillers (1μm) (Schott, Germany) were included into the paste. The glass ionomer Fuji II LC (GC, Japan) and the composite resin CeramX (Dentsply DeTrey, Germany) served as controls. The samples (10/group) were 22x2x2mm in size, polymerized with overlapping areas for 200s using a LED curing unit (Bluephase C8, 1090mW/cm2, Ivoclar Vivadent, Liechtenstein) and stored in water for 24h at 37°C before subjecting them to the three point flexural test (Zwick Z010 ; Zwick, Germany) at a 20mm span with a crosshead speed 0.75 mm/min. Statistical analysis of the data was performed using Mann-Whitney test (α=0.05). Results: CeramX showed statistically higher flexural strength than all other tested materials (91MPa). The ACP composite with 10% barium fillers (35MPa) and with 10% silica fillers (32MPa) was not significantly different from control Fuji II LC (33MPa). Values for all other ACP containing materials ranged from 20-27MPa and were not significantly different from the ACP composite without added fillers. Conclusion: This study showed that ACP composite resins reinforced with 10% barium glass or 10% silica fillers have improved mechanical properties, similar to a currently used resin modified glass ionomer material.

amorphous calcium phosphate; composite resins; flexural strength

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