## 4 Discussion  
Peri-implantitis treatment is still a challenge for the clinicians. To be successful, it is mandatory to perform a deep decontamination of the infected tissues around the dental implants, as well as the exposed fixture parts. With the aim to improve the implant osseointegration, in the last years, scientists have developed anodized, machinated and sandblasted dental implant surfaces, which, due to their high roughness, are difficult to decontaminate; moreover, an optimal treatment procedure or a suitable instrument is not yet available. In the literature, several approaches (mechanical-manual decontamination techniques, disinfection using chemical agents, implantoplasty of exposed fixture parts, laser therapy) were proposed for the decontamination of the infected implant parts by different authors, but there is still no consensus on which is the most predictable, reproducible and effective procedure [26]. Because of their ablation, bactericidal and bio-stimulator effects, dental lasers were proposed, including a utility tool for decontaminating the infected implant surfaces. However not all of them proved effective, and their improper use or settings could cause damage to peri-implant tissue and/or to implant fixtures. The main problem related to dental-laser use is the thermal effect on the titanium implant surfaces; in fact, its overheating can cause an increase of bone temperature over 47 \({}^{\circ}\)C with heat-induced bone injury and compromise osseointegration. Another key point is the possibility that the radiation emitted by the dental laser, because of its moderate absorption rate on titanium, could damage the implant fixtures, for example, with crater formation on their surface. However, these events are rarely reported in the in vivo study and mainly depend on the improper choice of the dental laser type and on the irradiation parameters settings. Er:YAG, CO\({}_{2}\) and diode lasers are the most documented due to their efficacy and more reliable application; when used with the correct emission power and for the appropriate time, it is scientifically known that they do not generate alterations of the implant surfaces and of the bone that surrounds them [11]. [PERSON] published a paper to show the results obtained after testing the possible presence of thermal damage induced by \(\lambda\) = 808 nm GaAlAs diode laser irradiation on various titanium discs [27]. The aim of the authors was to identify, in vitro, the optimal laser settings to decontaminate the different implant surfaces with a diode laser (\(\lambda\) = 808 nm). The outcome of these experiments showed a different absorption of laser radiation and,therefore, a different overheating depending on the manufacturing characteristics of the titanium surfaces. In particular, the highest temperature values were obtained on the rough fixture parts, corresponding to the endo-osseous implant portion. In contrast, the glossy implant parts caused lesser heating and faster cooling because of the high reflectivity of the surfaces. Laser radiation scattered from the glossy implant surface can induce undesired damage on the peri-implant and surrounding tissues. However, by using appropriate setting parameters, the laser radiation can be absorbed by adjacent periodontal tissues, promoting bio-stimulation and anti-phlogistic effect. The authors concluded their analysis by specifying that appropriate cautions must be dedicated when treating the implants parts in contact with alveolar bone to avoid overheating-related injuries, and irradiation parameters should be tailored. [PERSON] and his co-workers analyzed the effects of Neodymium-Doped Yttrium Aluminum Garnet (Nd:YAG) and Holmium-Doped Yttrium Aluminum Garnet (Ho:YAG), Er:YAG, CO\({}_{2}\) and GaAlAs (diode laser) lasers with an electron microscope on four types of implant surfaces: mechanized, with sandblasting and treatment acid, titanium plasma sprayed and hydroxyapatite-coated [28].