A comparison of decontamination methods of tried-in preformed metal crowns: an in-vivo study

To compare the effectiveness of different decontamination methods on tried-in preformed metal crowns (PMCs).

Sixty unused PMCs and 90 tried-in PMCs from patients were assessed for contamination after culturing for 24 h on liquid media, solid media and differential media for identification of Streptococcus mutans, Staphylococcus aureus, and Escherichia coli. Subsequently, these PMCs were divided equally into the following six groups: autoclave (121 °C, 15 psi for 15 min), 5% sodium hypochlorite (5 min), 5% glutaraldehyde (5 min), 70% isopropyl alcohol (1 min) and normal saline (5 min). The contamination was reassessed, and the Log₁₀ counts were compared to the pre-decontamination levels using one way ANOVA and paired t-test at a significance level of p < 0.05.

The mean percentage reduction in colony counts was significantly more in the autoclave group compared to glutaraldehyde or sodium hypochlorite groups, glass bead, isopropyl alcohol, and normal saline in this decreasing order.

PMCs supplied by the manufacturer were found to be sterile and can be used directly on patients. The autoclave was the best method of sterilisation, although it did not eliminate the microbes 100%; followed by 5% glutaraldehyde and 5% sodium hypochlorite.