S Mutans Sticks to Ceramics, Too

Photo by the Centers for Disease Control and Prevention.


Photo by the Centers for Disease Control and Prevention.

Commonly found inhabiting the oral cavity, Streptococcus mutans is a leading cause of dental caries. It’s also tough to beat because its receptors improve its adhesion to natural tooth surfaces. But how does this bacteria interact with crowns?

One recent in vitro study investigated how commercially available preparations of lithium disilicate ceramic materials influence bacterial adherence. The researchers fabricated 17 rectangular specimens measuring 10 by 10 by 4 mm for each type of lithium disilicate material from Ivoclar Vivadent’s IPS e.max line: pressed (Press), milled (CAD), fluorapatite layered (ZirPress/Ceram), and glazed (Ceram Glaze).

The surface roughness of each specimen was assessed before incubation with wild-type S mutans for 48 hours at 37°C with brain heart infusion broth media under anaerobic conditions. Adherent bacteria were sonicated, diluted, and plated in triplicate for quantification using the plate count method to assay for colony forming units (CFUs) as an indication of bacterial viability.

Next, the researchers performed statistical analysis with the Statistical Package for the Social Sciences software package from IBM using an analysis of variance followed by the Tukey Honestly Significant Difference test (α = 0.05). The Pearson r was used to evaluate the correlation between surface roughness and adherence.

The results showed a strong positive association between bacterial count and surface roughness (r = 0.95, P < 0.001). The surface roughness of Ceram Glaze (1.32 +/- 0.19 µm) was significantly the highest, followed by ZirPress/Ceram (0.71 +/- 0.09 µm), Press (0.11 +/- 0.02 µm), and CAD (0.10 +/- 0.02 µm) (F = 5/13898, P < 0.001). Accordingly, the CFUs of S mutans were the highest for Ceram Glaze (61.82 +/- 13.76), followed by ZirPress/Ceram (28.53 +/- 2.40), CAD (12.86 +/- 1.70), and Press (6.62 +/- 2.74) (F= 201.721, P < 0.001).

The article, “Adherence of Streptococcus Mutans on Lithium Disilicate Porcelain Specimens,” was published in The Journal of Prosthetic Dentistry. It was written by Diane T. Vo, DDS; Elaine Romberg, PhD; Carl F. Driscoll, DMD; Mary Ann Jabra-Rizk, PhD; and Radi Masri, DDS, MS, PhD, all of the University of Maryland, Baltimore; and Dwayne Arola of the University of Washington, Seattle.

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