## 4 Discussion  
Peri-implantitis treatment still represents a challenge in dentistry. Our study has been developed with a meticulous protocol consisting of the usual periodontal instrumentation with the addition of laser treatments; this approach finds support from numerous studies in the scientific literature. [PERSON] et al. observed a significant improvement of peri-implantitis with a combination of ultrasonic debridement, soft tissue curettage, glycine air powder polishing and Povidone-iodine, as a non-surgical approach [17]. [PERSON] et al. [18], with an experimental study in an animal model, stated that low-abrasion air polishing induced the smallest amount of tissue damage compared with hand instrumentation and ultrasonic scalers; this is surely important in the optical of minimally invasive dentistry that represents an unavoidable topic in modern dentistry. [PERSON] et al. [19], with an in vitro study, demonstrated that hand instrumentation (Gracey uncrettes), ultrasonic devices and air powder abrasive devices were not effective in the achievement of an optimal debridement of implant surfaces. Therefore, laser-assisted treatments have been proposed to overcome the abovementioned important limits of traditional therapies. PDT has been proposed with the use of low-level laser therapy (LLLT), although with clear limits, particularly due to absence of efficient bactericidal activity because of low power; low release of singlet oxygen with a frequency that does not exceed 1000 Hz because of long pulse time; and low penetration capacity.LLLT, however, has the important characteristic of biostimulation, that means stimulation of cells activity to achieve tissue regeneration [20,21]. An implementation of this treatment modality has been developed with the use of HLLT with the addition of Sioxyl Solution (OHLLT), combining high peak power (>2 W in order to eliminate pathogens in the oral cavity) with low mean power (<0.8 W in order to cause biostimulation); in this way, the temperature does not exceed 45 \({}^{\circ}\)C (range of tissue vasodilitation) [9]. OHLLT, with a frequency higher than 7000 Hz (as determined by the pulse length in microseconds), causes a continuous emission of singlet oxygen, causing destruction of pathogenic bacteria (this is in accordance with [PERSON] protocols) [9]. OHLLT has been shown to be effective in reducing the amount of total bacteria on contaminated implant surfaces [9], in particular in association with hydrogen peroxide [22,23]. Many protocols were proposed in the literature for implant surfaces' decontamination, such as the use of Er:YAG lasers that seem to enhance bacterial decontamination [24,25]. [PERSON] et al., in a recent randomized controlled clinical trial, found that Er:YAG lasers may advance bacterial decontamination because they noticed a statistically significant reduction in pocket depth measurements, although there were no improvements in clinical attachment level (CAL), gingival index (GI) or radiographic bone level. The authors concluded that \"larger sample size and longer follow-up is needed to confirm if Er:YAG laser irradiation provides additional clinical benefits for peri-implantitis regenerative therapy\" [26]. [PERSON] et al. [27], in a recent meta-analysis, evaluated 49 articles, but only seven met the strict inclusion criteria during the quality assessment. The studies included were: [PERSON] et al. [28], [PERSON] et al. [5], [PERSON] et al. [29], [PERSON] et al. [30], [PERSON] et al. [31], [PERSON] et al. [32] and [PERSON] et al. [33]. They concluded that \"a high-power diode laser may have some effect on peri-implant pathogens causing peri-implantitis, whereas Er:YAG laser application shows no significant effect on oral bacteria in the long term. aPDT (antimicrobial photodynamic therapy) has the ability to reduce the total count of the different bacterial strains associated with peri-implantitis, e.g., _A. actinomycetemcomitants_, _P. gingivalis_, _P. intermedia_, _T. denticola_, _T. forsythia_, _F. nucleatum_, and _C.