Photomedicine and Laser Surgery Volume 25, Number 4, 2007 © Mary Ann Liebert, Inc. Pp. 250–256 DOI: 10.1089/pho.2006.2067 Effect of the Diode Laser on Bacteremia Associated with Dental Ultrasonic Scaling: A Clinical and Microbiological Study MOHAMMAD ASSAF, 1,2 SELCUK YILMAZ, 2 BAHAR KURU, 2,3 SEBNEM DIRIKAN IPCI, 2 ULKU NOYUN, 2,3 and TANJU KADIR 3 ABSTRACT Objective: The purpose of this study is to evaluate the potential use of diode lasers (DLs) to reduce bacteremia associated with ultrasonic scaling (US). Furthermore, the clinical efficacy of DLs as an adjunct to US in the treatment of gingivitis was investigated. Background Data: Recently, lasers have found new applications in dental practice. The benefits of the use of DLs as an adjunct to US have not yet been determined. Methods: Twenty-two gingivitis patients were treated using a split-mouth study design in which each side was randomly treated by US alone or DL followed by US (DL  US). Blood samples were drawn just before and during US in each treatment step to detect induced bacteremia. Clinical parameters including plaque index, sulcus bleed- ing index, probing depth, and relative attachment level were recorded at baseline and 4 weeks postopera- tively. Results: Bacteremia was detected in 15 patients (68%) after US alone, and in 8 patients following DL  US (36%). The reduction of the incidence of odontogenic bacteremia during US after the application of DL was statistically significant (p  0.05). Clinical signs improved eventually, with no significant differences be- tween the two treatment regimens (p  0.05). Conclusions: Application of DL energy can reduce bacteria in gingival crevices which may reduce bacteremia following US. The use of DL did not show additional clinical influence on gingival healing after treatment of gingivitis with US. 250 INTRODUCTION Since their introduction in the 1960s, lasers have been used in many different fields in medicine and dentistry. 1,2 Among many lasers investigated in dentistry, diode lasers (DLs), as well as Nd:YAG, Er:YAG, and CO 2 lasers have demonstrated bac- tericidal effects which are promising for periodontal therapy. 3–8 In an experiment on rats, Fontana et al. 3 applied DL into in- duced periodontal pockets using a range of power settings (0.4, 0.6, 0.8, 1.0, and 1.2 W). They reported that DL was able to eliminate many different subgingival microorganisms and the reduction in the concentration of bacteria did not seem to be dependent on the laser’s power output. Moritz et al. 4 delivered pulsed DL energy at a power output of 2.5 W into human pe- riodontal pockets after scaling. Irradiation caused considerable bacterial elimination from periodontal pockets at a much higher level than the scaling-alone group, especially Actinobacillus actinomycetemcomitans. Later, Moritz et al. 9 performed a clin- ical study using DL energy as an adjunct to periodontal treat- ment. The pulsed irradiation at 2.5 W (50 Hz, pulse duration 10 msec) was performed three times during the experimental period at 1 week, 2 months, and 4 months after scaling. At 6 months, the bacterial reduction was significantly higher and the improvement of bleeding on probing scores and pocket depths were greater when compared to the control group, which was rinsed with H 2 O 2 after scaling. They concluded that DL ther- apy, in combination with scaling, supports the healing process of periodontal pockets by the elimination of bacteria. Low energy levels of DL therapy can reduce inflammation in periodontal tissues, which may be attributed to bacterial elim- ination, among other possible reasons. 10–12 Qadri et al. 10 eval- uated the clinical effects of DL energy (635 and 830 nm at 10 1 Faculty of Dentistry, Al-Quds University, Jerusalem. 2 Faculty of Dentistry, Yeditepe University, Istanbul, Turkey. 3 Faculty of Dentistry, Marmara University, Istanbul, Turkey.