Purpose: This study examined the impact of Porphyromonas gingivalis infection on rheumatoid arthritis (RA) in collagen-induced arthritis model mice (RA model mice).

 Materials and methods: We used eight-week old DBA/J1 mice as the RA model mice. We prepared antigen solution and adjuvant from bovine type II collagen as an emulsion and sensitized the model mice at 8 and 11 weeks to induce arthritis. For the experimental group, we used a group infected with P. gingivalis ATCC33277 strain (n=12). For the control group, we used a carboxy methylcellulose (CMC) administered group (n=12). We suspended P. gingivalis in 2.5% CMC, and administered a 0.1 ml aliquot directly inside of the mouth of the mice every other day at the concentration of 1×10⁹ CFU/ml. For the control group, we directly administered 0.1 ml of 2.5% CMC intraorally to the mice every other day. From the beginning of the experiment, we performed a clinical evaluation of arthritis every day using the method of Sarkar et al. Each week, we measured the body weight of the mice. On day 42, we sampled the mandible, joints from four limbs, and serum to examine the following items. To confirm P. gingivalis infection, we examined serum antibody titer with ELISA. We also analyzed MMP-3 and ACPA, which are clinical markers for rheumatoid arthritis, with ELISA. We evaluated micro CT images and the histological morphology of the mandibles and four limbs. The obtained results were statistically processed with Stat View software.

 Results: In the experimental group, serum antibody titer of P. gingivalis increased significantly, confirming the bacterial infection. The experimental group presented advanced redness and swelling in the extremities of four limbs compared to the control group. Forty-two days after the clinical evaluation of arthritis, the experimental group had an arthritis score that was 1.9 times greater than in the control group. The μCT analysis confirmed a significant increase in bone absorption in the experimental group compared to the control group through resorption images of alveolar bone. The experimental group exhibited swelling and bone deformation in the extremities of the four limbs, breaking of carpal cartilage, rough surface of knee joints, and rough surface of patella. MMP-3 values of the experimental group increased significantly compared to the control group. ACPA values of the experimental group also increased significantly compared to the control group. Knee joint tissues of the experimental group presented advanced invasion of inflammatory cells and damage to bones compared to the control group. MMP-13 immunostaining confirmed MMP-13 positive cells on the pannus and meniscus in the experimental group. The number of MMP-13 positive cells increased significantly compared to the control group.

 Conclusions: The results of this study suggested that oral infection of P. gingivalis accelerates destruction of the knee joints in collagen-induced arthritis model mice.

 Purpose: Despite its important role in the control of periodontal disease, mechanical plaque removal is not properly practiced by most individuals. Given the current limitations, new approaches for the control of biofilm are required. Our goal was to investigate the potential of egg yolk antibody (IgY)-containing film for the control of periodontal bacteria.

 Materials and methods: We assessed the egg yolk antibody-containing film “periguard Ⅳ.” This product is an edible film-type supplement containing IgY believed to be useful for controlling bacteria associated with periodontitis and biofilm formation, including Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, and Prevotella intermedia. Patients administered IgY-containing film for two weeks. After a two-week recovery period, a placebo film that did not contain IgY was administered for an additional two weeks. Saliva was collected four times before and after each treatment period and the number of periodontal bacteria in the saliva was measured. Pathogenic periodontal bacteria in the saliva were quantified using real-time PCR.

 Results: A. actinomycetemcomitans was not detected in any of the patients. The levels of P. gingivalis, T. forsythia, and T. denticola decreased greatly following treatment with the IgY-containing film, but the level of P. intermedia increased. The IgY-containing film appeared to decrease the amount of periodontal bacteria in patients that originally had high levels.

 Conclusion: The IgY-containing film decreased periodontal bacteria except for P. intermedia, but increased periodontal bacteria when the number of periodontal bacteria was initially low. This result suggests that IgY-containing film should be used carefully in chronic periodontitis patients.

 Purpose: Recently developed self-adhesive resin cement that does not require pretreatment is now available on the market. However, it is considered that postoperative pain after inlay restoration may be related to the acidity of the dental cement immediately after mixing. Therefore, we measured the pH values of different self-adhesive resin cements and investigated the determinations of pH after mixing.

 Methods: Maxcem Elite (Kerr), Clearfil SA Cement Automix (Kuraray Noritake) and RelyX Unicem 2 Automix (3M ESPE) were used as the test materials. The mixing of each material was carried out according to the manufacturer’s instructions. Advantec pH paper was immersed in distilled water and allowed to react with the sample for 3 min. Referring to the standard pH color chart, the pH value was determined immediately after mixing, and 5 min, 10 min, 24 h, 48 h and 72 h after mixing. The data was statistically analyzed using Tukey’s test (n=3).

 Results: Maxcem Elite showed no significant change between immediately after and 72 h after mixing (pH=3.0). The pH of Clearfil SA Cement Automix and RelyX Unicem 2 Automix immediately after mixing was 2.5 and 2.8, respectively, but rose to 7.4 and 6.2 after 72 h.

 Conclusion: The pH of Clearfil SA Cement Automix and RelyX Unicem 2 Automix was low immediately after mixing but approached neutrality after 72 h. On the other hand, the pH of Maxcem Elite remained low from immediately after mixing to 72 h after mixing.