Antibacterial effects of 2.94 µm Er:YAG laser radiation on root surfaces : an in vitro study

Aim of the study

This study evaluates the laser antimicrobial effects, previously demonstrated in in vitro culture, on pathogenic organisms on root surfaces in vitro. The period of radiation exposure required was also assessed.

Materials and methods

One hundred and twenty-five teeth that had been extracted for various reasons and stored in physiological saline solution. They were cleaned, then varnished except for an area of 4 x 4 mm and sterilised. They were divided into 5 groups and each group inoculated with a strain of bacteria (Escherichia coli, Staphylococcus aureus, Actinobacillus actinomycetemcomitans, Eikenella corrodens, Peptostreptococcus micros) and incubated. The surfaces were then irradiated and the number of remaining viable bacteria counted.

Results

The number of E. coli was progressively reduced to 32.2 % after 55 pulses, to 14.2 % after 75 pulses and to 5.5 % after 105 pulses. S. aureus was reduced to 15.1 % after 105 pulses, A. actinomycetemcomitans to 8.3 % after 75 pulses, E. corrodens to 3 % after 75 pulses and P. micros to 22 % after 75 pulses.

Conclusion

The use of the laser has been shown to effectively remove plaque and calculus from root surfaces. It has been shown here that it is effective on cultures on root surfaces as well as on certain periodontal pathogens.

Commentary

The Er:YAG laser (2.94 µm) has proven efficacy. However, after 75 and even 105 pulses it does not produce complete sterilisation of bacterial colonies. How effective would it be on biofilm ? This is an appealing technique but its cost/benefit remains to be seen.