Yasuo Hosaka

Fusobacterium nucleatum enhances invasion of human gingival epithelial and aortic endothelial cells by Porphyromonas gingivalis

Invasion by Porphyromonas gingivalis has been proposed as a possible mechanism of pathogenesis in periodontal and cardiovascular diseases. Porphyromonas gingivalis have direct access to the systemic circulation and endothelium in periodontitis patients by transient bacteremia. Periodontitis can be described as one of the predominant polymicrobial infections of humans. In the present study, P. gingivalis strains were tested for their ability to invade a human gingival epithelial cell line (Ca9-22) and human aortic endothelial cells in coinfection with Fusobacterium nucleatum using antibiotic protection assays. Coinfection with F. nucleatum resulted in 2-20-fold increase in the invasion of host cells by P. gingivalis strains. The invasive abilities of P. gingivalis strains were significantly greater when incubated with a F. nucleatum clinical isolate (which possesses strong biofilm-forming ability), than when incubated with a F. nucleatum-type strain. In inhibition assays with metabolic inhibitors, a difference in inhibition profiles was observed between mono- and polymicrobial infections. Collectively, our results suggest that F. nucleatum facilitates invasion of host cells by P. gingivalis. Investigations of polymicrobial infection of host cells should improve our understanding of the role of P. gingivalis in periodontal infection and proatherogenic mechanisms.

Effect of Initial Periodontal Therapy on Oral Health–Related Quality of Life in Patients With Periodontitis in Japan

BACKGROUND It is becoming increasingly important for periodontists and dental hygienists to take a biopsychosocial approach to care when considering periodontal interventions. However, information on how patients perceive periodontitis and its treatment is limited. The purpose of the present study is to gain insight into the patient perception of oral health and the impact that periodontitis and treatment have on self-assessed quality of life (QoL). METHODS This was a prospective, two-center, clinical study in Japan. Patients with periodontitis were assessed for their perceptions of oral health by using an instrument for oral health-related QoL (OHRQL) before and after initial periodontal therapy. RESULTS A total of 58 patients (mean age: 53.6 years; 23 male and 35 female) participated in the study and completed initial periodontal therapy. At baseline, 97% of the patients perceived that their oral health status impacted on their QoL in one or more ways. Pain, eating and chewing, and psychologic function were identified as compromised OHRQL domains. More than one-half of the patients rated their overall oral health as poor. Initial periodontal therapy, consisting mainly of oral hygiene instructions and scaling and root planing, significantly improved OHRQL scores (P = 0.0027). The effect size was calculated to be 0.51, indicating a moderate improvement. Compared with baseline, a significantly higher proportion of patients reported rarely or never having a problem regarding OHRQL domains such as pain (P = 0.0049) and eating and chewing (P = 0.0145) after treatment. No significant difference in the OHRQL improvement was found with respect to disease severity. CONCLUSIONS Periodontitis negatively affected QoL in this population of Japanese patients with periodontitis. Conventional non-surgical periodontal therapy has a potential to ameliorate patient perceptions of oral health.

Antibacterial activity of povidone-iodine against an artificial biofilm of Porphyromonas gingivalis and Fusobacterium nucleatum

OBJECTIVE To investigate the antibacterial activity of povidone-iodine (PVP-I) on an artificial dual species biofilm of periodontal pathogens. DESIGN Porphyromonas gingivalis or Fusobacterium nucleatum grown in broth culture was inoculated on polycarbonate membrane (PCM) tissue culture inserts. After incubation for 72 h, PVP-I solutions were applied to the biofilm for the time period ranging from 0.5 to 5 min. After addition of a deactivator, each PCM was removed and the biofilm on the PCM was serially diluted and plated on blood agar plates and cultured anaerobically for 7 days. Then viable bacteria were enumerated. RESULTS In the dual species biofilm model, F. nucleatum showed an approximately 200-fold increase in viable counts when compared with mono-microbial biofilm. In dual species biofilm, PVP-I with concentration equal to or greater than 2% was required to significantly reduce P. gingivalis and F. nucleatum. When the contact time of PVP-I was increased to 1 min or greater, no difference in antibacterial activity of PVP-I was observed in any concentration. CONCLUSION These results suggest that 30s application of 2% PVP-I would be effective in suppressing both P. gingivalis and F. nucleatum in dual-species biofilm, and this provides clinical implication for the control of subgingival biofilm.

Improvement of hydrogelation abilities and handling of photocurable gelatin-based crosslinking materials.

Three types of eosin-derivatized gelatins (eosin-gelatins) with different molecular weights (M(w)) of ca. 15 kDa (low-molecular-weight eosin-gelatin, LEG), ca. 30 kDa (medium-molecular-weight eosin-gelatin, MEG), and ca. 95 kDa (high-molecular-weight eosin-gelatin, HEG) were prepared. All the eosin-gelatins except for HEG dissolved completely in water at 37 degrees C within several hours even at high concentrations of 35 or 40 wt % along with polyamine (poly(N,N-dimethylaminopropylacrylamide)) to produce photo-crosslinkable materials. The materials had appropriate viscosity for in situ molding at 37 degrees C and could be handled as a liquid at low temperatures of up to 25 degrees C. Upon photoirradiation for several tens of seconds, the materials were converted almost completely to hydrogels in the desired form with a microporous network structure by the radical coupling reaction. The mechanical strength of the produced hydrogels could be controlled by selecting a particular molecular weight or concentration of eosin-gelatins. The hydrogels obtained from LEG (40 wt %) or MEG (35 wt %) had elasticity similar to that of goat periodontal tissue. The handling of the photo-crosslinkable materials at room temperature and their photogelation ability were drastically improved by reducing the M(w) of eosin-gelatin. The potential usefulness of the photo-crosslinkable materials to periodontal regeneration has been discussed.

The Efficacy of Povidone-Iodine Products against Periodontopathic Bacteria

A total of 8 strains of 6 bacterial species, Porphyromonas gingivalis ATCC33277 and TDC286, Actinobacillus actinomycetemcomitans ATCC29523 and JP2, Fusobacterium nucleatum No. 2, Tannerella forsythensis ATCC43937, Prevotella intermedia ATCC25611 and Streptococcus anginosus ATCC33397, were treated with povidone-iodine (PVP-I) gargle (PVP-I: 0.47 and 0.23% w/v) or chlorhexidine gluconate (CHG) gargle (CHG: 0.002% w/v) for 15, 30 or 60 s, after which they were inoculated into various media, cultured and counted for residual bacteria. At both concentrations, PVP-I gargle reduced the viable cell count of all 8 bacterial strains to below the measurable limit within 15 s. By contrast, there were more than 1,000 viable colonies 60 s following treatment with the CHG gargle. The results demonstrate that povidone-iodine gargle has rapid bactericidal activity against the causative bacteria of periodontal disease.