A PRELIMINARY-STUDY ON THE EFFECTS OF THE NDYAG LASER ON ROOT SURFACES AND SUBGINGIVAL MICROFLORA INVIVO

THE PURPOSE OF THIS STUDY was to examine the effects of root preparation using the pulsed Nd:YAG laser, either alone or in combination with manual instrumentation. Study specimens consisting of 18 teeth with associated periodontal pockets from 8 different patients were treated as follows: 5 specimens were root planed with curets followed by laser exposure for 3 minutes using energy settings of 3.0 W at 20 pps; 2 specimens were root planed and then laser treated for 3 minutes using settings of 2.25 W and 20 pps; 4 specimens were treated by laser for 1 minute at settings of 1.75 W and 20 pps followed by root planing; 4 specimens were treated by laser only for 1 minute using settings of 1.75 W and 20 pps; and the remaining 3 teeth served as untreated controls. Both prior to and after completion of the laser and root planing treatments, microbiological samples were obtained from the treated pockets and submitted to a commercial laboratory for analysis of levels of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia. With the exception of two 7-day specimens, all others were extracted immediately post-therapy and processed for SEM examination. All treated specimens, regardless of treatment sequence, exhibited some degree of laser-induced root surface alteration. Notably, laser-treated calculus deposits were free of their characteristic surface layer of microbial plaque. Microbial sampling indicated a post-therapy reduction in levels of all 3 putative microbial pathogens compared to pre-treatment samples and control specimens. However, SEM examination revealed residual deposits of plaque and calculus in all treatment groups. Subgingival use of Nd:YAG lasers appears to be technique sensitive and long-term therapeutic benefits remain to be established.