ABSTRACT
BACKGROUND: Periodontal diseases are associated with dysbiosis in the oral microbial communities. Managing oral biofilms is therefore key for preventing these diseases. Management protocols often include over-the-counter antimicrobial mouth rinses, which lack data on their effects on the oral microbiome's ecology, bacterial composition, metabolic activity, and dysbiosis resilience. This study examined the efficacy of antimicrobial mouth rinses to halt dysbiosis in in vitro oral biofilms under periodontitis-simulating conditions. METHODS: Multispecies oral biofilms were grown on hydroxyapatite discs (HADs) and rinsed daily with one of six mouth rinses. Positive and negative controls were included. After three rinses, biofilms were analyzed with viability quantitative polymerase chain reaction and visualized using scanning electron microscopy. Supernatants of rinsed biofilms were used for metabolic activity analysis. In addition, human oral keratinocytes were exposed to rinsed biofilms to assess their inflammatory response. All outputs were analyzed for correlation using Spearman coefficient. RESULTS: Product-related changes were observed in the rinsed biofilms. Three of the six tested mouth rinses could significantly prevent dysbiosis with ≥30% reduction in pathobiont abundance relative to the control. These biofilms had lower metabolic activity, and the exposed human oral keratinocyte produced less interleukin-8. Interleukin-8 production correlated to both pathobiont quantity and the metabolic activity of the biofilms. CONCLUSION: Some mouth rinses could support biofilm resilience and stop dysbiosis evolution in the biofilm model, with a clear product-related effect. Such mouth rinses can be considered for patients under maintenance/supportive periodontal therapy to prevent/delay disease recurrence. Others are more useful for different periodontal therapy stages.
ABSTRACT
Peri-implantitis is a growing pathological concern for dental implants which aggravates the occurrence of revision surgeries. This increases the burden on both hospitals and the patients themselves. Research is now focused on the development of materials and accompanying implants designed to resist biofilm formation. To enhance this endeavor, a smart method of biofilm inhibition coupled with limiting toxicity to the host cells is crucial. Therefore, this research aims to establish a proof-of-concept for the pH-triggered release of chlorhexidine (CHX), an antiseptic commonly used in mouth rinses, from a titanium (Ti) substrate to inhibit biofilm formation on its surface. To this end, a macroporous Ti matrix is filled with mesoporous silica (together referred to as Ti/SiO2), which acts as a diffusion barrier for CHX from the CHX feed side to the release side. To limit release to acidic conditions, the release side of Ti/SiO2 is coated with crosslinked chitosan (CS), a pH-responsive and antimicrobial natural polymer. Scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDX) and Fourier transform infrared (FTIR) spectroscopy confirmed successful CS film formation and crosslinking on the Ti/SiO2 disks. The presence of the CS coating reduced CHX release by 33% as compared to non-coated Ti/SiO2 disks, thus reducing the antiseptic exposure to the environment in normal conditions. Simultaneous differential scanning calorimetry and thermogravimetric analyzer (SDT) results highlighted the thermal stability of the crosslinked CS films. Quartz crystal microbalance with dissipation monitoring (QCM-D) indicated a clear pH response for crosslinked CS coatings in an acidic medium. This pH response also influenced CHX release through a Ti/SiO2/CS disk where the CHX release was higher than the average trend in the neutral medium. Finally, the antimicrobial study revealed a significant reduction in biofilm formation for the CS-coated samples compared to the control sample using viability quantitative polymerase chain reaction (v-qPCR) measurements, which were also corroborated using SEM imaging. Overall, this study investigates the smart triggered release of pharmaceutical agents aimed at inhibiting biofilm formation, with potential applicability to implant-like structures.
