J Periodontol • March 2001 Periodontal Treatment With an Er:YAG Laser Compared to Scaling and Root Planing. A Controlled Clinical Study F. Schwarz,* A. Sculean, † T. Georg, ‡ and E. Reich † 361 Background: The aim of the present study was to compare the effectiveness of an Er:YAG laser to that of scaling and root plan- ing for non-surgical periodontal treatment. Methods: Twenty patients with moderate to advanced periodontal destruction were treated under local anesthesia and the quadrants were randomly allocated in a split-mouth design to either Er:YAG laser using an energy level of 160 mJ/pulse and 10 Hz or scaling and root planing (SRP) using hand instruments. Clinical assess- ments of plaque index (PI), gingival index (GI), bleeding on prob- ing (BOP), probing depth (PD), gingival recession (GR), and clin- ical attachment level (CAL) were made prior to and at 3 and 6 months after treatment. Subgingival plaque samples were taken at each appointment and analyzed using darkfield microscopy for the presence of cocci, non-motile rods, motile rods, and spirochetes. Differences in clinical parameters and prevalence of bacterial species were analyzed using the paired t-test. Results: The PI remained nearly unchanged while a significant reduction of the GI occurred in both groups after 6 months (P ≤0.001, P ≤0.001, respectively). The mean value of BOP decreased in the laser group from 56% at baseline to 13% after 6 months (P ≤0.001) and in the SRP group from 52% at baseline to 23% after 6 months (P ≤0.001). The mean value of the PD decreased in the laser group from 4.9 ± 0.7 mm at baseline to 2.9 ± 0.6 mm after 6 months (P ≤0.001) and in the SRP group from 5.0 ± 0.6 mm at baseline to 3.4 ± 0.7 mm after 6 months (P ≤0.001). The mean value of the CAL decreased in the laser group from 6.3 ± 1.1 mm at baseline to 4.4 ± 1.0 mm after 6 months (P ≤0.001) and in the SRP group from 6.5 ± 1.0 mm at baseline to 5.5 ± 1.0 after 6 months (P ≤0.001). The reduction of the BOP score and the CAL improvement was significantly higher in the laser group than in the SRP group (P ≤0.05, P ≤0.001, respectively). Both groups showed a significant increase of cocci and non-motile rods and a decrease in the amount of motile rods and spirochetes. Conclusions: An Er:YAG laser may represent a suitable alter- native for non-surgical periodontal treatment. J Periodontol 2001;72: 361-367. KEY WORDS Gingival index; lasers/therapeutic use; periodontal diseases/ therapy; planing; scaling; comparison studies; follow-up studies. * Previously, Department of Periodontology and Conservative Dentistry, University of the Saarland, Homburg, Germany; currently, Department of Oral and Maxillofacial Surgery, Ludwig Maximilians University, Munich, Germany. † Department of Periodontology and Conservative Dentistry, University of the Saarland. ‡ Institute of Medical Biometrics, Epidemiology and Medical Informatics. S ince the ruby laser was intro- duced in 1960, 1 lasers have been used in many different areas in medicine and their use in den- tistry was introduced in 1964. 2 Today various laser systems are discussed for a possible use in dentistry. The Nd:YAG (neodymium-doped: yttrium, aluminum, and garnet) and CO 2 (car- bon dioxide) lasers are limited due to their thermal side effects, whereas the Er:YAG (erbium-doped: yttrium, alu- minum, and garnet) laser is expected to show efficiency in medical and den- tal applications because of its thermo- mechanical ablation mechanism and the high absorption of its wavelength by water. 3-7 A primary goal in the treatment of periodontitis is the removal of bacterial deposits and halt- ing of disease progression. 8 To achieve this goal, a complete removal of adherent plaque, calculus, and infected cementum is necessary, even though complete removal is rare. 9,10 The nature of a laser depends on its wave- length. Close attention has been paid to the clinical applicability of the Er:YAG laser with its wavelength of 2.94 μm in the near infrared spectrum. This wavelength is well absorbed by water because the peak is close to the absorption coefficient of water. Con- sequently an Er:YAG laser has a water absorption characteristic approxi- mately 15 times greater than that of the CO 2 and 20,000 times greater than the Nd:YAG laser. 11,12 The appli-