Electrolyzed Saline Targets Biofilm Periodontal Pathogens In Vitro.

Preventing the development and recurrence of periodontal diseases often includes antimicrobial mouthrinses to control the growth of the periodontal pathogens. Most antimicrobials are nonselective, targeting the symbiotic oral species as well as the dysbiosis-inducing ones. This affects the overall microbial composition and metabolic activity and consequently the host-microbe interactions, which can be detrimental (associated with inflammation) or beneficial (health-associated). Consequently, guiding the antimicrobial effect for modulating the microbial composition to a health-associated one should be considered. For such an approach, this study investigated electrolyzed saline as a novel rinse. Electrolyzed saline was prepared from sterile saline using a portable electrolysis device. Multispecies oral homeostatic and dysbiotic biofilms were grown on hydroxyapatite discs and rinsed daily with electrolyzed saline (EOS). Corresponding positive (NaOCl) and negative (phosphate-buffered saline) controls were included. After 3 rinses, biofilms were analyzed with viability quantitative polymerase chain reaction and scanning electron microscopy. Supernatants of rinsed biofilms were used for metabolic activity analysis (high-performance liquid chromatography) through measuring organic acid content. In addition, human oral keratinocytes (HOKs) were exposed to EOS to test biocompatibility (cytotoxicity and inflammation induction) and also to rinsed biofilms to assess their immunogenicity after rinsing. Rinsing the dysbiotic biofilms with EOS could reduce the counts of the pathobionts (>3 log10 Geq/mm2 reduction) and avert biofilm dysbiosis (≤1% pathobiont abundance), leading to the dominance of commensal species (≥99%), which altered both biofilm metabolism and interleukin 8 (IL-8) induction in HOKs. EOS had no harmful effects on homeostatic biofilms. The scanning electron micrographs confirmed the same. In addition, tested concentrations of EOS did not have any cytotoxic effects and did not induce IL-8 production in HOKs. EOS showed promising results for diverting dysbiosis in in vitro rinsed biofilms and controlling key periopathogens, with no toxic effects on commensal species or human cells. This novel rinsing should be considered for clinical applications.

Oral Biofilm Cryotherapy as a Novel Ecological Modulation Approach.

Oral cryotherapy is used in dentistry as a safe, simple, and low-cost treatment for a variety of oral lesions. It is well known for its ability to aid in the healing process. However, its effect on oral biofilms is unknown. As a result, the purpose of this study was to assess the effects of cryotherapy on in vitro oral biofilms. In vitro multispecies oral biofilms were grown on the surface of hydroxyapatite discs in symbiotic or dysbiotic states. CryoPen X+ was used to treat the biofilms, whereas untreated biofilms served as control. One set of biofilms was collected for study immediately after cryotherapy, whereas another group was reincubated for 24 h to permit biofilm recovery. Changes in biofilm structure were analyzed with a confocal laser scanning microscope (CLSM) and a scanning electron microscope (SEM), while biofilm ecology and community compositional changes were analyzed with viability DNA extraction and quantitative polymerase chain reaction (v-qPCR) analysis. One cryo-cycle immediately reduced biofilm load by 0.2 to 0.4 log10 Geq/mL, which increased with additional treatment cycles. Although the bacterial load of the treated biofilms recovered to the same level as the control biofilms within 24 h, the CLSM detected structural alterations. Compositional alterations were also detected by SEM, corroborating the v-qPCR findings that showed ≈≤10% incidence of pathogenic species compared to nontreated biofilms that encompassed ≈45% and 13% pathogenic species in dysbiotic and symbiotic biofilms, respectively. Spray cryotherapy showed promising results in a novel conceptual approach to the control of oral biofilms. Acting selectively by targeting oral pathobionts and retaining commensals, spray cryotherapy could modify the ecology of in vitro oral biofilms to become more symbiotic and prevent the evolution of dysbiosis without the use of antiseptics/antimicrobials.