Antimicrobial and physicochemical properties of experimental light curing composites with alkali-substituted calcium phosphate fillers.

Objective: The antimicrobial and physicochemical properties of experimental light curing composites prepared with fillers made of mechanically activated alkali-substituted calcium phosphates like CaKPO(4), CaNaPO(4) or Ca(2)KNa(PO(4))(2) were compared with a commercial silane-modified cristobalite filler.

Methods: The antimicrobial properties were tested using Streptococcus mutans, Staphylococcus aureus and a clinically isolated plaque mixture. The potential for reducing bacteria growth on modified composites was determined using the proliferation reagent WST-1, which enables the measurement of metabolic activity and therefore the colonization with living bacteria. Investigated material properties included the degree of conversion and a test of flexural strength.

Results: All alkali-substituted composites provide a changed, mainly basic micro-milieu leading to a reduction of bacteria population with respect to the non-modified composite of about 25-70% with a flexural strength of cured composites in the range of 55-77 MPa complying with the clinical standard and a degree of conversion of 44-66%.

Significance: This study suggests that the modified composites increase antimicrobial properties while basic composite characteristics are not influenced by the filler.