## 3 Results
### Group 1--Use of Er:YAG Laser in Peri-Implantitis Treatment (Table 1)  
[PERSON] et al. tested the effectiveness of an Er:YAG laser with mechanical debridement in a randomized control trial [12]. Twenty patients with a total of 32 dental implants affected by moderate-to-severe peri-implant lesions were treated by using a Er: YAG laser with a cone-shaped glass-fiber tip with a wavelength of 2.9 nm and a power of 100 mJ/pulse (test group), or mechanical debridement with plastic curette and antiseptic treatment with 0.2% chlorheximide digluconate (control group). Plaque index (PI), bleeding on probing (BOP), probing depth (PD), gingival recession (GR) and clinical attachment level (CAL) were measured at the baseline and after 3 and 6 months. After 6 months, the BOP mean value decreased in the test group from the initial 83% to 31% (\(p<0.001\)), and in the control group, it decreased from 80% to 58% (\(p<0.001\)). The sites treated with the Er:YAG laser showed a mean change in CAL from 5.8 \(\pm\) 1 mm (baseline) to 5.1 \(\pm\) 1.1 mm (\(p<0.01\)) after 6 months. In the control group, patients showed a mean change in CAL from 6.2 \(\pm\) 1.5 mm (baseline) to 5.6 \(\pm\) 1.6 mm (\(p<0.001\)) after 6 months; consequently, the difference between the two groups was not statistically significant (\(p<0.05\)) [12]. Similar results were found by [PERSON] after conducting a randomized controlled trial on 42 patients equally distributed in a control and a test group with the purpose to compare abrasive air-flow therapy versus Er:YAG laser therapy [13]. No statistically different results were achieved between the control and test group after 6 months, in terms of bleeding on probing and probing depth. Another study conducted by [PERSON] et al. revealed no statistically significant differences between the application of an Er:YAG (ERL) and conventional plastic curette + sterile saline therapy (CPS) [14]. In this work, the authors evaluated the clinical outcomes obtained after a 48-month follow-up between a test group treated with ERL and a control group treated with CPS. Patients of both groups were preliminarily subjected to a complete surgical granulation tissue reaction and implantoplasty in the exposed fixtures parts. Unmodified implant surface areas were subsequently randomly treated with Er:YAG laser instrumentation (test group) or with plastic curettes and cotton pellets soaked in sterile saline (control group). Finally, in both groups, intrabony defects were treated with bovine bone (NBM) and coated with a collagen membrane (CM). Clinically significant improvements in BOP values and significant gains in PD and CAL were observed in both CPS and ERL groups. After 24 months, in ERL was found a greater reduction in BOP if compared with CPS group (ERL: 75.0 \(\pm\) 32.6% vs. CPS: 54.9 \(\pm\) 30.3%). However, after 48 months, the CPS-treated group was associated with a greater reduction in BOP, while the ERL-treated sites appeared to have relapsed. A comparative study conducted in Austria by [PERSON] et al. analyzed the results obtained with three different therapeutic interventions for peri-implantitis treatments [15]. Seventy-two patients were treated by Er:YAG laser decontamination (Group 1), 47 with implantoplasty (Group 2) and 23 with a combination of both techniques (Group 3). The  
Figure 7: Funnel plot to show the risk of bias in the analyzed study: (**a**) CAL gain in Er:YAG laser group (\(p=1.0000\)), (**b**) PPD reduction in Er:YAG laser group (\(p=1.0000\)) and (**c**) PPD reduction in diode laser group (\(p=1.0000\)). overall treatment success rate was 88.7% after 9 years of follow-up. The success rate following laser decontamination, implantoplasty and a combination of both therapeutic approaches was 91.9%, 87.2% and 82.6%, respectively.