Comparative Evaluation of the Effects of Different Photoablative Laser Irradiation Protocols on the Gingiva of Periodontopathic Patients

Objective: We aimed at quantifying the presence of periodontopathogens in gingival biopsies from periodontitis patients treated with different photoablative lasers (diode GaAs, Er:YAG, Nd:YAG, and CO2 lasers) and histologically analyzing their effects on the gingiva. Background data: Substantial evidence indicates that intracellular location of periodontal bacteria in the gingival epithelium may contribute to chronic periodontitis. Methods: Sixteen adult subjects with chronic periodontitis were subjected to conventional scaling/root planing and topical chlorhexidine, and immediately laser-irradiated on the inner and outer free gingiva. Small gingival biopsies were subjected to real-time polymerase chain reaction and cytofluorescence to identify periodontopathogens; tissue damage and endothelial ICAM-1 expression were assessed by histological and immunofluorescence analyses. Results: High DNA levels of Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, Treponema denticola, Prevotella intermedia, and Ekenella corrodens, were detected in all samples. Nd: YAG and diode lasers were capable of eradicating periodontopathogenic bacteria endowed within gingival epithelial cells outside periodontal pockets, without causing connective tissue damage and microvessel rupture. They also reduced ICAM-1 immunolabelling by the vascular endothelium. Conversely, Er: YAG lasers induced marked microvessel rupture and bleeding and failed to completely and selectively ablate the infected gingival epithelium, whereas CO2 laser caused heat-induced coagulation of the lamina propria. Conclusions: This study indicates that periodontopathogens can persist within cells outside the pocket epithelium, despite conventional periodontal treatment. Nd: YAG and diode lasers are able to eradicate intra-and extracellular bacteria from these sites, suggesting that they can be considered suitable devices to improve the clinical outcome of periodontal disease.