[The antimicrobial efficacy of an erbium laser on Streptococcus mutans. In vivo study]

This study was conducted in order to demonstrate the bactericidal effect of an erbium laser (Er,Cr:YSGG) on Streptococcus mutans, in vivo, at different laser power settings, obtaining sterile enamel surfaces with minimal tissue ablation. The practicians use the laser for the cutting effect on hard tissue to eliminate all the infected and affected enamel and dentine, without collateral damage on the pulp and for its bactericidal effect on cariogenic bacteria.

The study group included 132 superficial carious lesions, on 66 patients with ages between 6 and 20; a two-year study (January 2006 - November 2008) performed in a private practice. The carious lesions were ablated with an erbium laser with two types of tips. A sample of occlusal plaque was taken using a sterile swab, soaked in normal saline solution (before and after the preparation).

Before the laser treatment, the percentage with high counts of Streptococcus mutans was 70% and low counts 30% (chi2 = 26.16 ; p < 0.01). At the laser power of 4,5 watts, the zirconium tip (Z6) had a higher number of sterile culture (96,3%). The numbers of sterile cultures were higher at the laser power of 5 watts, with both tips: zirconium and sapphire, the percentage being equal: 91-92%.