The American Academy of Periodontology (AAP) recently embarked on a Best Evidence Consensus (BEC) model of scientific inquiry to address questions of clinical importance in the treatment of periodontal and peri-implant diseases. For each focused question addressed below, there is a critical mass of evidence. However, by itself, that evidence is, in the judgment of the expert panel convened by the AAP, insufficient to support broad conclusions and/or clinical practice guidelines. The members of the expert panel have extensive knowledge of laser therapy and experience using lasers in a broad range of clinical scenarios relevant to the management of periodontitis and peri-implant diseases. The panel performed systematic reviews on the subject, debated the merits of published data and experiential information, developed a consensus report, and provided "clinical bottom lines" based on the best evidence available. The panel recognizes the limitations imposed on assessing the potential clinical applications of laser-assisted therapy in the treatment of periodontitis and peri-implant diseases. The challenge in analyzing current evidence in these two clinical areas stems from several factors, including the diversity of lasers, the variety of energy settings employed, and the differing modes of delivery, which together create many combinations of factors that can result in differing clinical outcomes for patients. The expert panel looks forward to future clinical studies that will provide unequivocal answers to the role that the various available lasers can play in treating periodontitis and peri-implant diseases. In patients with moderate to severe periodontitis, do lasers used alone or as an adjunct to conventional forms of periodontal therapy provide better clinical outcomes than scaling and root planing alone? A literature search for randomized controlled clinical trials (RCTs) evaluating scaling and root planing versus laser therapy alone or laser therapy plus scaling and root planning, with or without surgical access, in the treatment of patients with moderate to severe periodontitis was conducted using the MEDLINE, EMBASE, and CENTRAL databases. A total of 475 articles published through March 2016 were identified. Of these, 28 met the selection criteria for review. These criteria required human clinical trials of ≥3 months' duration, with at least 10 adult subjects presenting, with mean probing depth ≥5 mm. (See Chambrone, Ramos, Reynolds1 2018 for detailed information on the literature review and results.) Current evidence suggests that, as an adjunct to conventional periodontal therapy, appropriate laser therapy may provide a modest additional benefit (< 1 mm) in clinical improvement in probing depth and clinical attachment level (CAL) compared with traditional forms of periodontal therapy in the treatment of moderate to severe chronic and aggressive forms of periodontitis. Although not conclusive, some evidence suggests that adjunctive use of Er:YAG or Nd:YAG lasers was superior to conventional periodontal therapy alone in deep periodontal pockets with probing depth ≥7 mm. At the same time, current evidence is inadequate to conclude that laser therapy alone is either superior or comparable to conventional periodontal therapy in terms of clinical improvement in probing depth and CAL in the treatment of moderate to severe chronic and aggressive forms of periodontitis. For residual probing depths ≥5 mm following conventional active periodontitis therapy and regular periodontal maintenance care for at least one year, current evidence is inadequate to conclude that laser therapy as an adjunct or alone provides any additional improvement in probing depth or clinical attachment level compared with conventional periodontal therapy.1 In patients with peri-implant mucositis or peri-implantitis, do lasers used alone or as an adjunct to conventional forms of therapy provide better clinical outcomes than scaling and root planing alone? A literature search for prospective and retrospective human case series, controlled clinical trials, or RCTs was conducted using three electronic databases and a hand search of peer-reviewed journals for relevant articles published in English between January 1980 and June 2016. Human clinical trials of ≥10 patients with peri-implant disease, treated with surgical/non-surgical approaches and laser therapy, and with a follow-up period of ≥6 months were included. The search yielded 237 articles for evaluation, and a total of 22 articles were selected, 13 with lasers used as an adjunct to non-surgical intervention and nine with lasers used with surgery. Among the selected 22 studies, only three included patients with peri-implant mucositis; the other 19 included patients with peri-implantitis. The outcomes of using laser as the sole method of therapy could not be evaluated because no controlled studies were identified. Therefore, all results represented outcomes of applying lasers as an adjunct to surgical/non-surgical treatment. (See Lin, López del Amo, Wang4 2018 for detailed information on the literature review and results.) Data on adjunctive laser treatment for peri-implant mucositis are scarce. No substantial current evidence conclusively supports their use in the treatment of peri-implant mucositis. Some evidence suggests clinical benefits with adjunctive laser use in the non-surgical treatment of peri-implantitis in the short term. However, no substantial evidence suggests long-term benefits. Such evidence includes successfully reaching certain definitive endpoints of care, such as bleeding on probing reduction, while failing to alter others, such as pocket depth reduction or gain in attachment or radiographic improvement. Limited evidence presented benefits that could be arguable (i.e., potential bacteria reduction) for adjunctive laser use with surgical treatment of peri-implantitis. However, no long-term benefits of adjunctive laser therapy for peri-implantitis have been reported, and long-term benefits must be interpreted with caution due to the critical role of maintenance care on long-term treatment outcomes for peri-implantitis. In patients with moderate to severe periodontitis or peri-implantitis, does antimicrobial photodynamic therapy (aPDT) as an adjunct to conventional forms of therapy provide better clinical outcomes than scaling and root planing alone? MEDLINE, EMBASE, and CENTRAL databases were searched for articles published up to and including March 2017. Articles that presented original data from RCTs, with a follow-up duration ≥3 months that evaluated scaling and root planing or implant surface scaling versus scaling and root planning, or implant surface scaling plus aPDT for the treatment of adult patients (≥18 years) with moderate to severe chronic/aggressive periodontitis or peri-implantitis were considered eligible for inclusion.5 A total of 730 articles published through March 2017 was identified and 28 were selected for review based on their meeting the selection criteria. (See Chambrone, Wang, Romanos5 2018 for detailed information on the literature review and results.) Antimicrobial photodynamic therapy is laser treatment used in conjunction with a photosensitizer and is intended to reduce periodontal pathogenic bacteria. Current evidence demonstrates that appropriate antimicrobial photodynamic therapy as an adjunct to conventional therapy may provide modest (< 1 mm) improvements in probing depths and clinical attachment levels when compared to conventional periodontal therapy for periodontitis. However, the difference in clinical outcomes suggested by the current evidence does not support clinical relevance for the combined therapy. More information is needed to provide a reliable estimate of the effect on clinical outcomes. Insufficient evidence was available to draw conclusions relative to the adjunctive effect of aPDT in the treatment of peri-implantitis. The BEC panel on laser therapy acknowledges the difficulty in drawing specific conclusions from the data of the RCTs referenced in the systematic reviews it considered. This difficulty is due to several factors, including the heterogeneity among studies, potential for study bias, and wide diversity in the types of lasers, energy settings, and modes of delivery utilized among the studies reviewed. The panel further recognizes there are several applications of laser therapy for which there is limited, and/or controversial, and/or contradictory evidence. As a result, the panel spent considerable time in discussion to arrive at a consensus on the current status of laser therapy, as well as recommendations for future research and training. The following sections summarize the consensus of the expert opinion of the panel. The American Academy of Periodontology Best Evidence Consensus meeting on lasers was sponsored by J. Morita USA (Irvine, California). Participants filed detailed disclosure of potential conflicts of interest relevant to the meeting topic, and these are kept on file. The authors receive, or have received, research funding, consultant fees, and/or lecture compensation from the following companies: BIOLASE (Irvine, California), J. Morita USA, and Millennium Dental Technologies (Cerritos, California).