Bacterial adhesion of Streptococcus mutans to provisional fixed prosthodontic material

Bacterial adhesion and formation of dental plaque on provisional fixed prosthodontic materials results in gingival inflammation and secondary caries.

The purpose of this in vitro study was to compare 10 commonly used provisional fixed prosthodontic materials (2 acrylic polymethyl methacrylates, 2 improved methacrylates, and 6 bisacrylate composite resins), based on their susceptibility to adhere to Streptococcus mutans, and examine the influence of surface roughness and hydrophobicity.

Surface roughness was assessed by perthometer and hydrophobicity by contact angle measurements. Streptococcus mutans suspension was incubated with 15 disk-shaped specimens for each material (10 x 2 mm) and examined with the fluorescence dye, Alamar Blue/resazurin, and an automated multidetection reader. Glass and the veneering composite resin, Sinfony, served as controls. Statistical analysis was performed using the Mann-Whitney U-test in combination with the Bonferroni adjustment. Additionally, scanning electron micrographs were made.

Median surface roughness values ranged between 0.04 microm and 0.08 microm, and median contact angles between 46.5 and 71 degrees. High relative fluorescence intensities (>10,000) were found for Snap, UniFast LC, and CronMix K plus, moderate values (5000-10,000) for Trim, Temphase, Structur Premium, and PreVISION CB, and lowest fluorescence intensities (<5000) were found for Cronsin, Protemp 3 Garant, and Luxatemp. Scanning electron micrographs displayed streptococcal monolayers on all investigated surfaces, indicating initial bacterial adhesion.

The quantity of bacterial adhesion differed significantly among the assessed provisional materials. A correlation between bacterial adhesion and surface roughness or hydrophobicity was not confirmed. Bisacrylate composite resins and acrylic polymethyl methacrylates had significantly lower adhesion potentials than improved methacrylates.