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 CO(2) 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 CO(2) 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.