Effect of antimicrobial agents on physical properties of dental cements

The release profile of the antimicrobial agents from α-tricalcium phosphate (α-TCP) and glass-ionomer cement containing Metronidazole, Cefaclor, or Ciprofloxacin was examined in our previous study, and revealed that the release behavior varied depending on the chemical structure of the drugs. However, the effect of drugs on physical properties of this cement has not been clarified in detail. The aim of this study was therefore to examine the effect of incorporation of antimicrobial agents on the mechanical strength and morphological feature of the cement. Each antimicrobial agent was added respectively to the commercially available α-TCP cements (New Apatite Liner Type I and Type II) and glass-ionomer cement (Base cement white). The compressive strength was measured after 24-hour immersion in water at 37°C. The cement samples were also observed before and after immersion foe 3 months by scanning electron microscopy. The strength data were statistically analyzed. The compressive strength of New Apatite Liner Type I cement containing antimicrobial agents decreased remarkably compared with that of the control cement. The degree of the decrease of the compressive strength varied depending on the antimicrobial agents. The SEM observation revealed that the incorporation of the drugs to the NAL-I cement revealed the formation of cement matrix was prevented, which is consisted of the crystals of hydroxyapatite. The effect of the drugs on compressive strength of New Apatite Liner Type II cement also varied depending on the drugs added. While, the addition of 3% antimicrobial agents to Base cements showed only slight decrease in compressive strength. There was no significant difference of the effect by the drugs on the compressive strength of the 3%-drug-loaded BS cement. The SEM photographs of the drug-loaded Base cement did not show any noticeable changes compared with the control cement. The matrix of the Base cement seemed not to be affected by the 3% addition of these drugs. It concluded that the changes in compressive strength by the addition of the antimicrobial agents corresponded with the morphological changes in the SEM images of these cements.