Atomic Force Microscopy: A three-dimensional reconstructive tool of oral microbiota in gingivitis and periodontitis

Characterization and morphological methods for oral biofilm visualization: where are we nowadays?

The oral microbiome represents an essential component of the oral ecosystem whose symbiotic relationship contributes to health maintenance. The biofilm represents a state of living of microorganisms surrounding themselves with a complex and tridimensional organized polymeric support and defense matrix. The substrates where the oral biofilm adhere can suffer from damages due to the microbial community metabolisms. Therefore, microbial biofilm represents the main etiological factor of the two pathologies of dental interest with the highest incidence, such as carious pathology and periodontal pathology. The study, analysis, and understanding of the characteristics of the biofilm, starting from the macroscopic structure up to the microscopic architecture, appear essential. This review examined the morphological methods used through the years to identify species, adhesion mechanisms that contribute to biofilm formation and stability, and how the action of microbicidal molecules is effective against pathological biofilm. Microscopy is the primary technique for the morphological characterization of biofilm. Light microscopy, which includes the stereomicroscope and confocal laser microscopy (CLSM), allows the visualization of microbial communities in their natural state, providing valuable information on the spatial arrangement of different microorganisms within the biofilm and revealing microbial diversity in the biofilm matrix. The stereomicroscope provides a three-dimensional view of the sample, allowing detailed observation of the structure, thickness, morphology, and distribution of the various species in the biofilm while CLSM provides information on its three-dimensional architecture, microbial composition, and dynamic development. Electron microscopy, scanning (SEM) or transmission (TEM), allows the high-resolution investigation of the architecture of the biofilm, analyzing the bacterial population, the extracellular polymeric matrix (EPS), and the mechanisms of the physical and chemical forces that contribute to the adhesion of the biofilm to the substrates, on a nanometric scale. More advanced microscopic methodologies, such as scanning transmission electron microscopy (STEM), high-resolution transmission electron microscopy (HR-TEM), and correlative microscopy, have enabled the evaluation of antibacterial treatments, due to the potential to reveal the efficacy of different molecules in breaking down the biofilm. In conclusion, evidence based on scientific literature shows that established microscopic methods represent the most common tools used to characterize biofilm and its morphology in oral microbiology. Further protocols and studies on the application of advanced microscopic techniques are needed to obtain precise details on the microbiological and pathological aspects of oral biofilm.

Efficacy of Periodontal Endodontics Combined with Diode Laser (DL) Therapy on Severe Periodontitis

Background

For a long time, the impact of severe periodontitis on the pulp has been the focus of periodontal clinical research. Whether the teeth with severe periodontitis should be treated with pulp has also become the focus of clinical research.

Aims

To explore the effect of periodontal endodontic therapy combined with DL therapy on severe periodontitis.

Materials and Methods

The clinical data of 100 patients with severe periodontitis from January 2020 to July 2022 were selected and included in the retrospective study. According to the different retrieval treatment methods, they were divided into the control group and the treatment group with 50 cases in each group. The control group received periodontal endodontic treatment, and the treatment group received DL treatment on the basis of the control group. The differences in periodontal probing depth (PD), toothache degree, bleeding index (BI), inflammatory factors, plaque index (PLI), and attachment loss (AL) between the two groups were compared and analyzed.

Results

After 3 months of treatment, the bleeding index (BI), plaque index (PLI), and periodontal probing depth (PD) of the treatment group were significantly lower than those of the control group, and the difference was statistically significant (P < 0.05). The attachment loss (AL) of the group was not significantly different from that of the control group (P > 0.05). Before treatment, there was no significant difference in the levels of inflammatory factors between the two groups (P > 0.05). After 3 months of treatment, the levels of IL-6 and CRP in the treatment group were significantly lower than those in the control group, and the difference was statistically significant (P < 0.05). Before treatment, there was no significant difference in the levels of inflammatory factors between the two groups (P > 0.05). After 3 days of treatment, the VAS score of the treatment group was significantly lower than that of the control group, and the difference was statistically significant (P < 0.05).After treatment, there were no complications during follow-up in the two groups.

Conclusion

The application of DL treatment has a significant effect, which can promote the healing of periodontal tissue, reduce the depth of periodontal pockets, and reduce the degree of toothache, thereby providing a reference for clinical treatment.

Fusobacterium nucleatum Subspecies Differ in Biofilm Forming Ability in vitro

Development of dysbiosis in complex multispecies bacterial biofilms forming on teeth, known as dental plaque, is one of the factors causing periodontitis. Fusobacterium nucleatum (F. nucleatum) is recognised as a key microorganism in subgingival dental plaque, and is linked to periodontitis as well as colorectal cancer and systemic diseases. Five subspecies of F. nucleatum have been identified: animalis, fusiforme, nucleatum, polymorphum, and vincentii. Differential integration of subspecies into multispecies biofilm models has been reported, however, biofilm forming ability of individual F. nucleatum subspecies is largely unknown. The aim of this study was to determine the single-subspecies biofilm forming abilities of F. nucleatum ATCC type strains. Static single subspecies F. nucleatum biofilms were grown anaerobically for 3 days on untreated or surface-modified (sandblasting, artificial saliva, fibronectin, gelatin, or poly-L-lysine coating) plastic and glass coverslips. Biofilm mass was quantified using crystal violet (CV) staining. Biofilm architecture and thickness were analysed by scanning electron microscopy and confocal laser scanning microscopy. Bioinformatic analysis was performed to identify orthologues of known adhesion proteins in F. nucleatum subspecies. Surface type and treatment significantly influenced single-subspecies biofilm formation. Biofilm formation was overall highest on poly-L-lysine coated surfaces and sandblasted glass surfaces. Biofilm thickness and stability, as well as architecture, varied amongst the subspecies. Interestingly, F. nucleatum ssp. polymorphum did not form a detectable, continuous layer of biofilm on any of the tested substrates. Consistent with limited biofilm forming ability in vitro, F. nucleatum ssp. polymorphum showed the least conservation of the adhesion proteins CmpA and Fap2 in silico. Here, we show that biofilm formation by F. nucleatum in vitro is subspecies- and substrate-specific. Additionally, F. nucleatum ssp. polymorphum does not appear to form stable single-subspecies continuous layers of biofilm in vitro. Understanding the differences in F. nucleatum single-subspecies biofilm formation may shed light on multi-species biofilm formation mechanisms and may reveal new virulence factors as novel therapeutic targets for prevention and treatment of F. nucleatum-mediated infections and diseases.