Biomedical Sciences and Comprehensive Care (Dentistry) Works
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Item The influence of biofilm maturation on fluoride’s anticaries efficacy(Springer, 2022-02) Ayoub, Hadeel M.; Gregory, Richard L.; Tang, Qing; Lippert, Frank; Biomedical Sciences and Comprehensive Care, School of DentistryObjectives (1) To explore the influence of biofilm maturation and timing of exposure on fluoride anticaries efficacy and (2) to explore biofilm recovery post-treatment. Methods Bovine enamel specimens were utilized in a pH cycling model (28 subgroups [n = 18]). Each subgroup received different treatments [exposure]: sodium fluoride [NaF]; stannous fluoride [SnF2]; amine fluoride [AmF]; and de-ionized water [DIW], at a specific period: early: days 1–4; middle: days 3–6; and late: days 7–10. During non-exposure periods, pH cycling included DIW instead of fluorides. Objective 1: part 1 (cycling for 4, 6, or 10 days). Part 2 (cycling for 10 days). Objective 2: early exposure: three sample collection time points (immediate, 3 days, and 6 days post-treatment); middle exposure: two sample collection time points (immediate, 4 days post-treatment). The enamel and biofilm were analyzed ([surface microhardness; mineral loss; lesion depth]; [lactate dehydrogenase enzyme activity; exopolysaccharide amount; viability]). Data were analyzed using ANOVA (p = 0.05). Results Objective 1: Early exposure to fluorides produced protective effects against lesion progression in surface microhardness and mineral loss, but not for lesion depth. Objective 2: Early exposure slowed the demineralization process. SnF2 and AmF were superior to NaF in reducing LDH and EPS values, regardless of exposure time. They also prevented biofilm recovery. Conclusion Earlier exposure to SnF2 and AmF may result in less tolerant biofilm. Early fluoride treatment may produce a protective effect against demineralization. SnF2 and AmF may be the choice to treat older biofilm and prevent biofilm recovery. Clinical relevance The study provides an understanding of biofilm-fluoride interaction with mature biofilm (e.g., hard-to-reach areas, orthodontic patients) and fluoride’s sustainable effect hours/days after brushing.Item The Zoom life is here to stay!(Allen Press, 2021-03) Thomas, Priya; Treat, Timothy; Biomedical Sciences and Comprehensive Care, School of DentistryItem Alveolar bone protection by targeting the SH3BP2-SYK axis in osteoclasts(Wiley, 2020-02) Kittaka, Mizuho; Yoshimoto, Tetsuya; Schlosser, Collin; Rottapel, Robert; Kajiya, Mikihito; Kurihara, Hidemi; Reichenberger, Ernst J.; Ueki, Yasuyoshi; Biomedical Sciences and Comprehensive Care, School of DentistryPeriodontitis is a bacterially induced chronic inflammatory condition of the oral cavity where tooth-supporting tissues including alveolar bone are destructed. Previously, we have shown that the adaptor protein SH3-domain binding protein 2 (SH3BP2) plays a critical role in inflammatory response and osteoclastogenesis of myeloid lineage cells through spleen tyrosine kinase (SYK). In this study, we show that SH3BP2 is a novel regulator for alveolar bone resorption in periodontitis. Micro-CT analysis of SH3BP2-deficient (Sh3bp2 -/- ) mice challenged with ligature-induced periodontitis revealed that Sh3bp2 -/- mice develop decreased alveolar bone loss (male 14.9% ± 10.2%; female 19.0% ± 6.0%) compared with wild-type control mice (male 25.3% ± 5.8%; female 30.8% ± 5.8%). Lack of SH3BP2 did not change the inflammatory cytokine expression and osteoclast induction. Conditional knockout of SH3BP2 and SYK in myeloid lineage cells with LysM-Cre mice recapitulated the reduced bone loss without affecting both inflammatory cytokine expression and osteoclast induction, suggesting that the SH3BP2-SYK axis plays a key role in regulating alveolar bone loss by mechanisms that regulate the bone-resorbing function of osteoclasts rather than differentiation. Administration of a new SYK inhibitor GS-9973 before or after periodontitis induction reduced bone resorption without affecting inflammatory reaction in gingival tissues. In vitro, GS-9973 treatment of bone marrow-derived M-CSF-dependent macrophages suppressed tartrate-resistant acid phosphatase (TRAP)-positive osteoclast formation with decreased mineral resorption capacity even when GS-9973 was added after RANKL stimulation. Thus, the data suggest that SH3BP2-SYK is a novel signaling axis for regulating alveolar bone loss in periodontitis and that SYK can be a potential therapeutic target to suppress alveolar bone resorption in periodontal diseases.Item Optineurin regulates osteoblastogenesis through STAT1(Elsevier, 2020-05) Mizuno, Noriyoshi; Iwata, Tomoyuki; Ohsawa, Ryosuke; Ouhara, Kazuhisa; Matsuda, Shinji; Kajiya, Mikihito; Matsuda, Yukiko; Kume, Kodai; Tada, Yui; Morino, Hiroyuki; Yoshimoto, Tetsuya; Ueki, Yasuyoshi; Mihara, Keichiro; Sotomaru, Yusuke; Takeda, Katsuhiro; Munenaga, Syuichi; Fujita, Tsuyoshi; Kawaguchi, Hiroyuki; Shiba, Hideki; Kawakami, Hideshi; Kurihara, Hidemi; Biomedical Sciences and Comprehensive Care, School of DentistryA sophisticated and delicate balance between bone resorption by osteoclasts and bone formation by osteoblasts regulates bone metabolism. Optineurin (OPTN) is a gene involved in primary open-angle glaucoma and amyotrophic lateral sclerosis. Although its function has been widely studied in ophthalmology and neurology, recent reports have shown its possible involvement in bone metabolism through negative regulation of osteoclast differentiation. However, little is known about the role of OPTN in osteoblast function. Here, we demonstrated that OPTN controls not only osteoclast but also osteoblast differentiation. Different parameters involved in osteoblastogenesis and osteoclastogenesis were assessed in Optn−/- mice. The results showed that osteoblasts from Optn−/- mice had impaired alkaline phosphatase activity, defective mineralized nodules, and inability to support osteoclast differentiation. Moreover, OPTN could bind to signal transducer and activator of transcription 1 (STAT1) and regulate runt-related transcription factor 2 (RUNX2) nuclear localization by modulating STAT1 levels in osteoblasts. These data suggest that OPTN is involved in bone metabolism not only by regulating osteoclast function but also by regulating osteoblast function by mediating RUNX2 nuclear translocation via STAT1.Item Bioactive Materials Subjected to Erosion/Abrasion and Their Influence on Dental Tissues(Allen Press, 2020) Viana, Í. E. L.; Alania, Y.; Feitosa, S.; Feitosa, A. B.; Braga, R. R.; Scaramucci, T.; Biomedical Sciences and Comprehensive Care, School of DentistryObjective: The objective of this study was to evaluate the effect of erosion or erosion-abrasion on bioactive materials and adjacent enamel/dentin areas. Methods and Materials: Enamel and dentin blocks (4×4×2 mm) were embedded side by side in acrylic resin, and a standardized cavity (1.2×4×1.5 mm) was prepared between them. Preparations were restored with the following materials: composite resin (Filtek Z350, control); experimental composite containing di-calcium phosphate dihydrate particles (DCPD); Giomer (Beautifil II), high viscosity glass ionomer cement (GIC, Fuji IX); and a resin-modified GIC (Fuji II LC). The specimens were submitted to two cycling models (n=10): erosion or erosion-abrasion. The challenges consisted of five-minute immersion in 0.3% citric acid solution, followed by 60-minute exposure to artificial saliva. Toothbrushing was carried out twice daily, 30 minutes after the first and last exposures to acid. Dental and material surface loss (SL, in μm) were determined by optical profilometry. Data were analyzed with Kruskal-Wallis and Dunn tests (α=0.05). Results: Under erosion, for enamel, only the GIC groups presented lower SL values than Z350 (p<0.001 for Fuji IX and p=0.018 for Fuji II LC). For dentin, none of the materials showed significantly lower SL values than Z350 (p>0.05). For material, the GICs had significantly higher SL values than those of Z350 (p<0.001 for Fuji IX and p=0.002 for Fuji II LC). Under erosion-abrasion, the enamel SL value was significantly lower around Fuji II LC compared with the other materials (p<0.05). No significant differences were observed among groups for dentin SL (p=0.063). The GICs and Giomer showed higher SL values than Z350 (p<0.001 for the GICs and p=0.041 for Giomer). Conclusion: Both GIC-based materials were susceptible to erosive wear; however, they promoted the lowest erosive loss of adjacent enamel. Against erosion-abrasion, only Fuji II LC was able to reduce enamel loss. For dentin, none of the materials exhibited a significant protective effect.Item Imatinib has minimal effects on inflammatory and osteopenic phenotypes in a murine cherubism model(Wiley, 2021) Mukai, Tomoyuki; Akagi, Takahiko; Hiramatsu Asano, Sumie; Tosa, Ikue; Ono, Mitsuaki; Kittaka, Mizuho; Ueki, Yasuyoshi; Yahagi, Ayano; Iseki, Masanori; Oohashi, Toshitaka; Ishihara, Katsuhiko; Morita, Yoshitaka; Biomedical Sciences and Comprehensive Care, School of DentistryObjective Cherubism is a genetic disorder characterised by bilateral jawbone deformation. The associated jawbone lesions regress after puberty, whereas severe cases require surgical treatment. Although several drugs have been tested, fundamental treatment strategies for cherubism have not been established. The effectiveness of imatinib has recently been reported; however, its pharmaceutical mechanism remains unclear. In this study, we tested the effects of imatinib using a cherubism mouse model. Methods We used Sh3bp2 P416R cherubism mutant mice, which exhibit systemic organ inflammation and osteopenia. The effects of imatinib were determined using primary bone marrow-derived macrophages. Imatinib was administered intraperitoneally to the mice, and serum tumour necrosis factor-α (TNFα), organ inflammation and bone properties were examined. Results The cherubism mutant macrophages produced higher levels of TNFα in response to lipopolysaccharide compared to wild-type macrophages, and imatinib did not significantly suppress TNFα production. Although imatinib suppressed osteoclast formation in vitro, administering it in vivo did not suppress organ inflammation and osteopenia. Conclusion The in vivo administration of imatinib had a minimal therapeutic impact in cherubism mutant mice. To establish better pharmaceutical interventions, it is necessary to integrate new findings from murine models with clinical data from patients with a definitive diagnosis of cherubism.Item Peer Led Team Learning in a Foundational IPE Curriculum(Pacific University Libraries, 2020-09) Romito, Laura; Daulton, Brittany J.; Stone, Cynthia; Pfeifle, Andrea L.; Biomedical Sciences and Comprehensive Care, School of DentistryBACKGROUND The Peer Led Team Learning (PLTL) instructional model utilizes Peer Leaders, advanced students who mentor and guide student teams to collaborate on applied course concepts. PURPOSE To apply a modified PLTL model in the university’s foundational, longitudinal, competency-based interprofessional education (IPE) curriculum. METHODS Twelve Peer Leaders were selected, trained, and deployed as facilitators for interprofessional teams of students during the IPE curriculum’s first three large-scale learning events. Peer Leaders completed an evaluation of training, a facilitation skills survey, and participated in a semi-structured focus group interview process. RESULTS After participating in the PLTL program, Peer Leaders reported increased confidence in their interprofessional knowledge and facilitation skills. The primary challenge for Peer Leaders in facilitating teams was lack of student engagement (n=7, 58%). CONCLUSION PLTL is a feasible model for IPE settings. It has the potential to both increase facilitator capacity in interprofessional learning activities and have a positive impact on Peer Leaders.Item Effects of casein phosphopeptide-amorphous calcium phosphate crème on nicotine-induced Streptococcus mutans biofilm in vitro(Springer, 2020) Alawadhi, Naser B.; Lippert, Frank; Gregory, Richard L.; Biomedical Sciences and Comprehensive Care, School of DentistryObjectives The aim of this study was to test the effects of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) crème, or MI Paste™ (MIP), on nicotine-induced Streptococcus mutans biofilm. The experiment utilized S. mutans biofilm assays with varying concentrations of nicotine and MIP aqueous concentrate levels. First hand exposure to nicotine has been demonstrated to significantly increase S. mutans biofilm formation, while the active component, CPP-ACP, in MIP has been shown to reduce S. mutans biofilm formation. Materials and methods A 24-h culture of S. mutans UA159 in microtiter plates were treated with varying nicotine concentrations (0–32 mg/ml) in Tryptic Soy Broth supplemented with 1% sucrose (TSBS) with or without MIP aqueous concentrate. A spectrophotometer was used to determine total growth absorbance and planktonic growth. The microtiter plate wells were washed, fixed, and stained with crystal violet dye and the absorbance measured to determine biofilm formation. Results The presence of MIP aqueous concentrate inhibits nicotine-induced S. mutans biofilm formation at different concentrations of nicotine (0–32 mg/ml). Conclusion The results demonstrated nicotine-induced S. mutans biofilm formation is decreased in the presence of MIP. This provides further evidence about the cariostatic properties of CPP-ACP, the active soluble ingredient in the MIP, and reconfirms the harmful effects of nicotine. Clinical significance Smokers may gain dual benefits from the use of MIP, as a remineralization agent and as a cariostatic agent, by inhibiting nicotine-induced S. mutans biofilm formation.Item Growth and viability of Streptococcus mutans in sucrose with different concentrations of Stevia rebaudiana Bertoni(Springer, 2020) Escobar, E.; Piedrahita, M.; Gregory, R. L.; Biomedical Sciences and Comprehensive Care, School of DentistryObjective To evaluate total absorbance, planktonic growth, biofilm formation, viability, metabolic activity, and pH of Streptococcus mutans UA159 cultures when different dilutions of Stevia rebaudiana Bertoni were applied and to determine the minimum inhibitory concentration (MIC) and the minimum biofilm inhibitory concentration (MBIC) of Stevia on S. mutans. Materials and methods The effects of different dilutions of Stevia (0–400 mg/ml) on S. mutans total growth, planktonic growth, biofilm formation, viability, metabolic activity, and pH during a 72-h growth period were evaluated in this in vitro study. A stock solution was prepared by mixing 10 ml of tryptic soy broth (TSB) supplemented with 1% sucrose (TSBS) and 4 g of Stevia. Results S. mutans total growth and biofilm formation decreased with reduced concentrations of Stevia. Furthermore, the MIC was 25 mg/ml and the MBIC was 6.25 mg/ml. Complete eradication of S. mutans was not observed with any of the Stevia concentrations. Planktonic growth of S. mutans was not repressed by high concentrations of Stevia and most of the Stevia concentrations generated an increased pH. Conclusion Because Stevia reduces biofilm and acid production, Stevia can be considered a non-cariogenic sweetener. Clinical relevance This study confirms the anticariogenic effect of Stevia, like it has been previously reported, but more studies on the most effective concentration are needed, and in the present study, the minimum inhibitory concentration (MIC) and the minimum biofilm inhibitory concentration (MBIC) was determined in the presence of sucrose. Additionally, this is the first study to evaluate the effect of Stevia on S. mutans metabolic activity.Item In-Vitro Model of Scardovia wiggsiae Biofilm Formation and Effect of Nicotine(Scielo, 2020-09) Balhaddad, Abdulrahman A.; Ayoub, Hadeel M.; Gregory, Richard L.; Biomedical Sciences and Comprehensive Care, School of DentistryRecently, Scardovia wiggsiae has been reported to be strongly associated with caries formation. This study aimed to establish an in vitro model of S. wiggsiae biofilm and to investigate the effect of nicotine on S. wiggsiae colony-forming units (CFUs) growth. S. wiggsiae biofilm was grown overnight using brain-heart infusion (BHI) broth supplemented with 5 g of yeast extract/L (BHI-YE). The overnight culture was used as an inoculum to grow S. wiggsiae biofilm on standardized enamel and dentin samples. Samples were incubated with different nicotine concentrations (0, 0.5, 1, 2, 4, 8, 16 and 32 mg/mL) for 3 days. The dissociated biofilms were diluted, spiral plated on blood agar plates, and incubated for 24 h. CFUs/mL were quantified using an automated colony counter. A two-way ANOVA was used to compare the effect of different nicotine concentrations on S. wiggsiae CFUs. This study demonstrated that S. wiggsiae biofilm could be initiated and formed in vitro. Increased CFUs was observed through 0.5-4 mg/mL and 0.5-8 mg/mL of nicotine using enamel and dentin substrates, respectively. 16 and 32 mg/mL of nicotine were determined as the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC), respectively. S. wiggsiae formed greater biofilm on enamel than dentin specimens in response to the nicotine stimulus. This study demonstrated the negative effect of smoking on increasing S. wiggsiae biofilm. Establishing S. wiggsiae biofilm in vitro may allow researchers in the future to have a better understanding of caries pathogenesis and bacterial interaction.