In periodontology, lasers have been suggested for the nonsurgical treatment of chronic periodontitis. Many wavelengths were tested, but unfortunately, most parts were not efficient. An Nd:YAG laser was applied in a specific protocol named the laser-assisted new attachment procedure (LANAP). LANAP seems to facilitate the refurbishment of new tissues from supporting structures of the periodontium, wherein the unhealthy surface of the roots exhibits pristine attachments in human beings. Photodynamic therapy (PDT) was investigated too. The aim of our study is to show the effects of oxygen high-level laser therapy (OHLLT) in removing all bacterial deposits on the root or implant surface by means of mechanical instrumentation and laser irradiation compared to LANAP and to nonsurgical debridement of periodontal pockets. At 7 days post-treatment, a real-time PCR test had similar results on the OHLLT and LANAP groups. After 9 months, all periodontal pockets were treated successfully, not showing significant differences in the clinical results between OHLLT and LANAP and with a decrease in the plaque index, bleeding on probing and probing depth compared with the nonsurgical debridement group.