Which adjuvant laser therapy is superior to debridement alone and best promotes anti-inflammation and regeneration in peri-implantitis? A systematic review and network meta-analysis

Background: Peri-implantitis is a major factor responsible for a decrease in the long-term success rate of implants. Conventional mechanical debridement (MD) is not efficient enough to clear plaque from the surface of rough-threaded implants. Additional laser therapy may compensate for this deficiency and promote tissue regeneration by photobiomodulation.Objective: To evaluate the efficacy and ranking of adjuvant laser therapy for peri-implantitis with regards to inflammation control and tissue regeneration, data analysis of diode laser, antimicrobial photodynamic therapy (aPDT) and solid-state laser (erbium-doped yttrium aluminium garnet laser (Er:YAG) and erbium, chromium-doped yttrium, scandium, gallium and garnet (Er,Cr:YSGG)) for inflammation-related indicators, such as peri-implant probing depth (PPD), bleeding on probing (BOP), sulcular bleeding index (SBI), and plaque index (PLI), as well as regeneration-related indicators, such as clinical attachment level (CAL) and radiographic bone fill (RBF) were included in the systematic review and network meta-analysis. Methods: The EMBASE, Cochrane Library, Web of Science, and PubMed databases were searched till 12 March 2022 for records of randomised controlled blind clinical trials with a 24-week follow-up. World Health Organization-International Clinical Trial Registry Platform and ClinicalTrials.gov were used to revalidate the included trials and to search for completed but unpublished trials on 26 March 2022. We included four laser therapies for patients with peri-implantitis and bone defects, excluding single-or multi-arm clinical trials lacking laser-assisted MD. We extracted the general characteristics and associated outcomes from the included studies. The risk of bias was assessed according to the Cochrane Handbook for Systematic Reviews of Interventions, and evidence certainty was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation framework (GRADE) and confidence in network meta-analysis (CINeMA).The primary outcomes of the pairwise meta-analysis were PPD, BOP, CAL, PLI, and RBF, whereas those of the network meta-analysis were PPD, SBI, CAL, PLI, and RBF; all estimated weighted mean differences were under a random effects model. The PROSPERO number for this study is CRD42022334800.Results: A total of 18 studies with 901 participants were included. In the pairwise meta-analysis, MD with laser assistance performed better than MD alone for all outcomes. Among the outcomes, compared with MD alone, aPDT as an adjunct was significantly more effective in reducing BOP (weighted mean difference (WMD) = 8.20, 95% confidence interval (CI) range: 5.03-11.37), CAL (WMD = 0.44, 95% CI range: 0.40-0.48) and increasing RBF (WMD = 0.22, 95% CI range: 0.10-0.34), while diode laser as an adjunct (WMD = 0.28, 95% CI range: 0.08-0.47) was significantly more effective in PLI reduction. In network meta-analysis, aPDT as an adjunct was significantly more effective than MD alone in improving PPD (WMD = 0.67, 95% CI range: 0.44-0.87), CAL (WMD = 0.51, 95% CI range: 0.16-0.88) and RBF (WMD = 0.22, 95% CI range: 0.03-0.45). In terms of PPD reduction, both MD with adjuvant Er,Cr:YSGG and Er:YAG demonstrated significant advantages over adjuvant diode laser (WMD = 0.43, 95% CI range: 0.01-0.83 and WMD = 0.82, 95% CI range: 0.12-1.53, respectively) or MD alone (WMD = 0.69, 95% CI range: 0.44-0.9 and WMD = 1.09, 95% CI range: 0.49-1.68, respectively). The probability of optimal treatment from the Bayesian network meta-analysis exhibited that Er:YAG + MD (88. 4%), Er:YAG + MD (76.6%), aPDT + MD (92.5%), and diode laser + MD (63.3%) ranked first in PPD, SBI, CAL, and PLI improvement in peri-implantitis, respectively. However, there was a contradiction between the Bayesian network meta-analysis (Er:YAG + MD: 45.9%) and frequentist network meta-analysis (aPDT + MD: 48.5%) for the best efficacy ranking probability of RBF. Of the 18 trials, the certainty of the evidence ranged from high to very low, with three (16.7%) rated as high risk of bias, 14 (77.8%) at moderate risk of bias, and one (0.6%) at low risk of bias.Conclusions: The current evidence suggests that laser-assisted MD is superior to MD alone in the treatment of periimplantitis. Compared with other adjuvant laser therapies, Er:YAG and diode lasers were more effective in reducing inflammation, whereas aPDT could further achieve tissue regeneration for the treatment of periimplantitis.