Morphologic changes following in vitro CO2 laser treatment of calculus-ladened root surfaces

The purpose of this study was to compare morphologic changes following C02 laser or manual curette treatment of calculus-ladened tooth root surfaces.

Laser treatment consisted of repeated single passes with a 6 Watt focused beam at 20 pulses per second, a pulse length of 0.01 second, and a manufacturer's laser efficiency rating of 86% (i.e., the amount of total power delivered through the aperture). The rate of beam passage over the target surface was controlled at 4 mm/second using an 0.8 mm diameter tip. The calculated energy density was 240 J/cm2 for each pass of the beam. Scaled and root planed surfaces were treated with a standardized force of 600 grams using new curettes. Specimens were evaluated by scanning electron microscopy.

Laser-induced surface changes included charring, meltdown and resolidification of calculus mineral, and ablation of microbial plaque. Laser-treated specimens also exhibited residual calculus and microbial plaque deposits in areas directly adjacent to the beam path. Scaled and root planed surfaces featured smooth and/or scale like smear layers and islands of residual calculus and microbial plaque.

The rough surface topography resulting from laser treatment and residual calculus and microbial plaque deposits indicates that C02 laser treatment of exposed root surfaces is, at best, an adjunct to traditional methods of therapy.