Discussion

Currently, effective decontamination of contaminated implant surfaces remains challenging in peri-implantitis management, primarily due to the resistance of biofilms on micro-rough titanium surfaces. Although multiple chemical and physical approaches have been proposed, their relative efficacy remains inconsistent in the literature [11,12,20-24]. Therefore, this study compared the antimicrobial effectiveness of Er,Cr:YSGG laser irradiation, GalvoSurge electrolytic cleaning, and 0.12% CHX against Staphylococcus aureus biofilm under standardized in vitro conditions. Based on the findings, the null hypothesis was rejected.

All active decontamination protocols significantly reduced viable bacterial counts compared with untreated controls; however, differences in magnitude were observed. Er,Cr:YSGG laser irradiation demonstrated the greatest reduction, followed by GalvoSurge, while CHX showed the lowest antibacterial effect. This trend likely reflects the superior ability of physical methods to disrupt biofilm structure compared with chemical disinfection alone [11,12,16,22,25].

The superior performance of the Er,Cr:YSGSG laser may be attributed to its combined photomechanical and hydrokinetic effects at a wavelength of 2780 nm, which facilitate disruption of hydrated biofilm and removal of bacterial deposits from micro-rough surfaces while minimizing thermal damage under appropriate parameters [13,16,17,25]. The approximately 2.57-log reduction observed in this study supports its antimicrobial potential and is consistent with previous findings on erbium-family lasers [16,17,25,26].

GalvoSurge electrolytic cleaning also produced a marked reduction in bacterial counts. Its mechanism involves the generation of hydrogen bubbles at the implant surface, promoting detachment of biofilm and organic contaminants, particularly within implant threads and complex surface structures, through combined mechanical and electrochemical effects [27-32]. Although GalvoSurge achieved lower CFU values than CHX, the difference was not statistically significant. This may be explained by the use of a single-species biofilm model, limited sample size, and variability within groups, which may have reduced statistical power. In addition, CHX may still exhibit substantial antibacterial activity in less complex biofilm conditions, thereby reducing observable differences between treatments [20-22,33]. Clinical studies have nevertheless reported improvements in clinical parameters and radiographic bone fill when electrolytic decontamination is combined with regenerative approaches [34,35].

CHX at 0.12% demonstrated a measurable but comparatively limited antibacterial effect. Its mechanism, based on disruption of bacterial cell membranes through its cationic bisbiguanide structure, is well established [36-38]. However, its efficacy is restricted by limited penetration into structured biofilms and by the relatively low concentration used in this study [20-24,33,36]. Higher concentrations (1-2%) have been shown to produce stronger antimicrobial effects in peri-implantitis management [39,40]. Although CHX exhibits substantivity and prolonged antimicrobial activity [37,41], these properties appear insufficient for effective disruption of mature biofilm on rough implant surfaces. Additionally, its interaction with titanium surfaces has shown variable effects on wettability and residue formation, which may influence bacterial adhesion and recolonization [42,43]. The absence of a statistically significant difference between CHX and GalvoSurge should therefore be interpreted as a limitation of the experimental model rather than true equivalence in clinical efficacy.

A key strength of this study is the development and application of a standardized custom-designed 3D-printed peri-implant defect model, which allowed controlled exposure of implant threads while preserving the complex macrogeometry of the implant surface. Unlike conventional flat-surface models, this approach better reproduces the clinical challenge of biofilm contamination in peri-implant defects, where implant threads and irregular surface topography may limit access to decontamination procedures. Additionally, the study incorporated commercially available SLA titanium implants, standardized biofilm formation conditions, clinically relevant decontamination protocols, and quantitative microbiological assessment using CFU analysis, allowing direct comparison of different treatment modalities under controlled experimental conditions.

However, several limitations must be considered. The use of a single-species _Staphylococcus aureus _biofilm does not fully reproduce the complexity of peri-implantitis-associated polymicrobial biofilms, which involve diverse microbial communities, interspecies interactions, and increased resistance to antimicrobial interventions [20,21,33]. Additionally, the in vitro design does not account for important biological factors such as saliva, host immune response, tissue healing mechanisms, and functional loading conditions. CFU analysis reflects only cultivable bacterial populations and does not evaluate biofilm matrix composition, endotoxin levels, or viable-but-non-culturable microorganisms. Furthermore, this study focused primarily on antibacterial efficacy and did not assess potential alterations in implant surface morphology, chemical characteristics, or temperature changes associated with laser irradiation. The absence of surface characterization techniques, such as scanning electron microscopy and physicochemical analyses, limits conclusions regarding the preservation of implant surface integrity following decontamination procedures.

These limitations are supported by previous studies emphasizing the importance of biofilm complexity and implant surface characteristics. Khayat et al. highlighted the shift toward dysbiotic multispecies biofilms in peri-implant disease [44], while El Khoury et al. demonstrated that implant surface characteristics may influence long-term stability [45]. Similarly, Anka et al. and related histological studies underscore the need to evaluate both antibacterial efficacy and preservation of surface properties when assessing decontamination methods [46,47].

Clinically, the present findings suggest that physical decontamination methods, particularly Er,Cr:YSGG laser irradiation, may provide superior bacterial reduction compared with CHX alone. This supports the concept that effective peri-implantitis management requires disruption of biofilm structure in addition to antimicrobial action. However, translation to clinical practice should be approached cautiously. Future studies should incorporate multispecies biofilm models, assess implant surface alterations, and evaluate clinically relevant outcomes such as re-osseointegration and long-term stability. Optimization of laser parameters is also necessary to ensure effective decontamination while preserving implant surface integrity.