The Impact of Oxygen Concentration on the Postcuring of 3D-Printed Dental Resin.

PURPOSE: This study investigated the impact of reducing the oxygen concentration via nitrogen injection during the postcuring process of 3D-printed dental materials. MATERIALS AND METHODS: Resin specimens for dental crown and bridge (15-mm diameter, both 1-mm and 2-mm heights) were 3D-printed and rinsed. Subsequently, the postcuring process was conducted on nine groups categorized according to atmospheric conditions within the curing device (20% [control], 10%, and 5% oxygen) and curing times (10, 15, and 20 minutes). Surface roughness was measured using a gloss meter. Surface polymerization was confirmed through Fourier-transform infrared spectroscopy (FT-IR) analysis, and the flexural strength and elastic modulus of the specimens were measured using a universal testing machine. Water absorption and solubility were determined according to Inernational Organization for Standardization (ISO) standards. All evaluation criteria were statistically analyzed using one-way ANOVA and Tukey's post hoc test based on oxygen concentration. RESULTS: The elastic modulus did not show statistically significant differences in all groups. However, compared to the control group, the flexural strength, degree of conversion, and gloss significantly increased in the groups with decreased oxygen concentrations. Conversely, water solubility and water absorption significantly decreased in a few groups with reduced oxygen concentration. CONCLUSIONS: Reducing oxygen concentration through nitrogen injection during the postcuring process of 3D printing enhances the suitability of the dental prosthetic materials. The significant increase in flexural strength can particularly enhance the utility of these materials in dental prosthetics.

Effects of the multi-channeled oral irrigation (MCOI) unit in preventing dental plaque formation and gingivitis: A randomized controlled trial.

PURPOSE: To evaluate the efficacy of COMORAL a new multi-channeled oral irrigation (MCOI) unit with pulsating water jet, in plaque score reduction and gingivitis. METHODS: This was a single-blinded clinical randomized controlled trial (NCT05031260). Forty-two healthy subjects between 18 to 35 years old were initially recruited, and the control group (n = 20) and the intervention group (n = 17) were randomly assigned. Both groups were asked to brush their teeth one or two times a day without any supplementary oral hygiene products while the intervention group used COMORAL 3 times a day, 5 days a week. Clinical indices including gingival index (GI), plaque index (PI), bleeding on probing (BOP), pocket depth (PD), gingival recession (GR), and clinical attachment loss (CAL) were obtained at the baseline (D0), day 14 (D14), and day 28 (D28). Saliva was collected to examine the presence of periodontal pathogens. The repeated measures analysis of variance or generalized estimating equation was used to compare the interaction between groups and time points. The independent t-test or Mann-Whitney test were used for intergroup differences at each time point. RESULTS: At V0, PI, GI, BOP, and PD scores showed no differences between the two groups. At V1 and V2, these scores showed significant difference between two groups (P < 0.05) such that the intervention group showed gradual decreases while the control group showed no change. There were no differences in GR, CAL, and periodontal pathogens between the two groups. COMORAL showed improvement in reducing gingival inflammation and dental plaque formation adjuvant to routine toothbrushing in healthy adults. CLINICAL SIGNIFICANCE: The results of this study can be useful to clinicians when selecting oral hygiene devices that can help improve patients' routine oral hygiene practice and their overall oral health.

The maternal microbiome promotes placental development in mice.

The maternal microbiome is an important regulator of gestational health, but how it affects the placenta as the interface between mother and fetus remains unexplored. Here, we show that the maternal gut microbiota supports placental development in mice. Depletion of the maternal gut microbiota restricts placental growth and impairs feto-placental vascularization. The maternal gut microbiota modulates metabolites in the maternal and fetal circulation. Short-chain fatty acids (SCFAs) stimulate cultured endothelial cell tube formation and prevent abnormalities in placental vascularization in microbiota-deficient mice. Furthermore, in a model of maternal malnutrition, gestational supplementation with SCFAs prevents placental growth restriction and vascular insufficiency. These findings highlight the importance of host-microbial symbioses during pregnancy and reveal that the maternal gut microbiome promotes placental growth and vascularization in mice.

Orai3 Calcium Channel Contributes to Oral/Oropharyngeal Cancer Stemness through the Elevation of ID1 Expression.

Emerging evidence indicates that intracellular calcium (Ca2+) levels and their regulatory proteins play essential roles in normal stem cell proliferation and differentiation. Cancer stem-like cells (CSCs) are subpopulations of cancer cells that retain characteristics similar to stem cells and play an essential role in cancer progression. Recent studies have reported that the Orai3 calcium channel plays an oncogenic role in human cancer. However, its role in CSCs remains underexplored. In this study, we explored the effects of Orai3 in the progression and stemness of oral/oropharyngeal squamous cell carcinoma (OSCC). During the course of OSCC progression, the expression of Orai3 exhibited a stepwise augmentation. Notably, Orai3 was highly enriched in CSC populations of OSCC. Ectopic Orai3 expression in non-tumorigenic immortalized oral epithelial cells increased the intracellular Ca2+ levels, acquiring malignant growth and CSC properties. Conversely, silencing of the endogenous Orai3 in OSCC cells suppressed the CSC phenotype, indicating a pivotal role of Orai3 in CSC regulation. Moreover, Orai3 markedly increased the expression of inhibitor of DNA binding 1 (ID1), a stemness transcription factor. Orai3 and ID1 exhibited elevated expression within CSCs compared to their non-CSC counterparts, implying the functional importance of the Orai3/ID1 axis in CSC regulation. Furthermore, suppression of ID1 abrogated the CSC phenotype in the cell with ectopic Orai3 overexpression and OSCC. Our study reveals that Orai3 is a novel functional CSC regulator in OSCC and further suggests that Orai3 plays an oncogenic role in OSCC by promoting cancer stemness via ID1 upregulation.

GV1001 Inhibits the Severity of the Ligature-Induced Periodontitis and the Vascular Lipid Deposition Associated with the Periodontitis in Mice.

GV1001, a 16 amino acid peptide derived from the catalytic segment of human telomerase reverse transcriptase, was developed as an anti-cancer vaccine. Subsequently, it was found to exhibit anti-inflammatory and anti-Alzheimer's disease properties. Periodontitis is a risk factor for a variety of systemic diseases, including atherosclerosis, a process in which chronic systemic and vascular inflammation results in the formation of plaques containing lipids, macrophages, foam cells, and tissue debris on the vascular intima. Thus, we investigated the effect of GV1001 on the severity of ligature-induced periodontitis, vascular inflammation, and arterial lipid deposition in mice. GV1001 notably reduced the severity of ligature-induced periodontitis by inhibiting gingival and systemic inflammation, alveolar bone loss, and vascular inflammation in wild-type mice. It also significantly lowered the amount of lipid deposition in the arterial wall in ApoE-deficient mice receiving ligature placement without changing the serum lipid profile. In vitro, we found that GV1001 inhibited the Receptor Activator of NF-κB ligand (RANKL)-induced osteoclast formation and tumor necrosis factor-α (TNF-α)-induced phenotypic changes in endothelial cells. In conclusion, our study suggests that GV1001 prevents the exacerbation of periodontitis and atherosclerosis associated with periodontitis partly by inhibiting local, systemic, and vascular inflammation and phenotypic changes of vascular endothelial cells.

Phosphoric Acid Etch Partially Restores the Initial Bond Strength of Composite to Silver Diamine Fluoride-Treated Enamel Using Universal Adhesives.

BACKGROUND: Restoring bonding composite to silver diamine fluoride (SDF)-treated enamel is challenging. This study investigates if phosphoric acid etch restores composite bond strength to SDF-treated enamel using universal adhesives. METHODS: Twenty-four recently extracted permanent teeth were randomly divided into 4 (2 experimental (SDF) and 2 control (CTR)) groups: SDF+Water: SDF (1 min) then water rinse (15 mL); CTR+Water: no treatment and water rinse (15 mL); SDF+Etch+Water: SDF (1 min), 35% phosphoric acid (40 s) then water rinse (15 mL); CTR+Etch+Water no treatment, 35% phosphoric acid (40 s) then water rinse (15 mL). The enamel surface in all the groups was bonded (All-Bond Universal) to 4-5 mm composite blocks (Z-250). Each sample was sectioned, and 6-8 beams (1 mm × 1 mm) were selected. The micro-tensile bond strength was measured by dividing the micro-tensile force peak by the adhesive surface area. Univariate ANOVA and Chi-square were used for between-group comparisons with p < 0.05. RESULTS: SDF+Water had significantly lower tensile strength compared to all the groups (p < 0.05). Although no difference was found in the tensile strength between the SDF+Etch+Water and the CTR+Etch+Water, the SDF+Etch+Water had significantly more adhesive failures compared to the CTR+Etch+Water (p = 0.047). CONCLUSIONS: While phosphoric acid etch seems to restore the initial composite bond strength to SDF-treated enamel, the long-term success of composite restorations bonded to SDF-treated enamel may need further investigation.

Effects of over-the-counter at-home whitening products with LED light on surface roughness of partially- and fully crystalized CAD/CAM lithium disilicate ceramics.

The aim of this study is to evaluate the effect of over-the-counter (OTC) at-home whitening products with LED light on partially- and fully-crystalized CAD/CAM lithium disilicate ceramics. Two partially-crystalized CAD/CAM lithium disilicate ceramics, Amber Mill and IPS e.max CAD, and one fully-crystalized CAD/CAM lithium disilicate ceramic, n!ce Straumann, were used. The specimens were divided based on treatment with OTC whitening products: no treatment provided, Colgate Optic, Crest 3D and Walgreens Deluxe. The surface roughness of the specimens was evaluated with an optical profilometer and scanning electron microscopy. The three LED whitening products significantly increased the surface roughness and changed surface morphology of Amber Mill and IPS e.max CAD but no differences for n!ce Straumann. OTC at-home whitening products with LED light can significantly increase the surface roughness of restorations fabricated with these partially-crystalized CAD/CAM lithium disilicate ceramic restorations. However, these products do not increase the surface roughness of restorations fabricated with this fully-crystalized lithium disilicate ceramic.

The maternal microbiome promotes placental development in mice.

The maternal microbiome is an important regulator of gestational health, but how it impacts the placenta as the interface between mother and fetus remains unexplored. Here we show that the maternal gut microbiota supports placental development in mice. Depletion of the maternal gut microbiota restricts placental growth and impairs feto-placental vascularization. The maternal gut microbiota modulates metabolites in the maternal and fetal circulation. Short-chain fatty acids (SCFAs) stimulate angiogenesis-related tube formation by endothelial cells and prevent abnormalities in placental vascularization in microbiota-deficient mice. Furthermore, in a model of maternal malnutrition, gestational supplementation with SCFAs prevents placental growth restriction and vascular insufficiency. These findings highlight the importance of host-microbial symbioses during pregnancy and reveal that the maternal gut microbiome promotes placental growth and vascularization in mice.

Chronic Alcohol Exposure Promotes Cancer Stemness and Glycolysis in Oral/Oropharyngeal Squamous Cell Carcinoma Cell Lines by Activating NFAT Signaling.

Alcohol consumption is associated with an increased risk of several cancers, including oral/oropharyngeal squamous cell carcinoma (OSCC). Alcohol also enhances the progression and aggressiveness of existing cancers; however, its underlying molecular mechanism remains elusive. Especially, the local carcinogenic effects of alcohol on OSCC in closest contact with ingestion of alcohol are poorly understood. We demonstrated that chronic ethanol exposure to OSCC increased cancer stem cell (CSC) populations and their stemness features, including self-renewal capacity, expression of stem cell markers, ALDH activity, and migration ability. The ethanol exposure also led to a significant increase in aerobic glycolysis. Moreover, increased aerobic glycolytic activity was required to support the stemness phenotype of ethanol-exposed OSCC, suggesting a molecular coupling between cancer stemness and metabolic reprogramming. We further demonstrated that chronic ethanol exposure activated NFAT (nuclear factor of activated T cells) signaling in OSCC. Functional studies revealed that pharmacological and genetic inhibition of NFAT suppressed CSC phenotype and aerobic glycolysis in ethanol-exposed OSCC. Collectively, chronic ethanol exposure promotes cancer stemness and aerobic glycolysis via activation of NFAT signaling. Our study provides a novel insight into the roles of cancer stemness and metabolic reprogramming in the molecular mechanism of alcohol-mediated carcinogenesis.

Radiographic Changes to Silver Diamine Fluoride Treated Carious Lesions after a Rinsing Step.

Silver diamine fluoride (SDF) is radiopaque. This in vitro study compares the changes in the radiopacity of carious lesions after SDF application, potassium iodide (PI) application, and water rinse. Ten recently extracted human teeth were sectioned and divided into two groups (n = 10 in each group): Group 1 = SDF, Group 2 = SDF + PI. Teeth in Group 1 received SDF for 1 min and rinsed with 15 mL water. Group 2 received the same protocol with the addition of PI application for 1 min after SDF application. All samples were scanned with micro-computed tomography before SDF application, after SDF application, after PI application (group 2) and after water rinse. The radiopacity of the carious lesions increased significantly after SDF application in Group 1 and 2 (p < 0.017, p < 0.008, respectively). A significant increase in radiopacity after PI application was also observed in Group 2 (p < 0.008). Water rinsing significantly decreased the radiopacity in Group 1 and 2 (p < 0.017, p < 0.008, respectively), but the radiopacity remained significantly higher than the preoperative values (Group 1 p < 0.017, Group 2 p < 0.008). The radiopacity of carious lesions increases after SDF and SDF + PI applications. Water rinsing could reduce the radiopacity of SDF and SDF + PI treated carious lesions, and might reduce the content of SDF in carious lesions.

Shear Bond Strength of Composite Diluted with Composite-Handling Agents on Dentin and Enamel.

This in vitro study aimed to examine the shear bond strength of composite on the dentin and enamel substrates when mixed with different composite-handling agents (CHAs). Eighty extracted molars were embedded into acrylic resin and sectioned sagittally. On the prepared specimens, four groups of resin mixtures were bonded onto the enamel or dentin surfaces­composite only, composite mixed with Composite Wetting Resin (CWR), composite mixed with Brush and Sculpt (BS), and composite mixed with Modeling Resin (MR). All groups were prepared by mixing at a 1:1 ratio by weight. Each specimen was subjected to the shear bond strength test. After the test, adhesive or cohesive failures were examined at the fractured sites. Data were analyzed using one-way and two-way analysis of variance (ANOVA) and the Tukey post hoc test. All composite groups mixed with CHAs displayed a reduced shear bond strength on dentin and enamel substrates compared to composite alone (p < 0.05). The shear bond strength on dentin decreased in the following order: CWR > BS > MR. A similar pattern was observed on enamel, except that there was no statistically significant difference between BS and MR. Statistically significant interactions between resin mixtures and substrates were found (p < 0.001). On the dentin substrate, adhesive failure dominated while adhesive/cohesive failure dominated on the enamel substrate. Conclusions: The shear bonding strength of composite decreases when mixed with CHAs on both dentin and enamel substrates.

Hyperlipidemia is necessary for the initiation and progression of atherosclerosis by severe periodontitis in mice.

Hyperlipidemia is a major risk of atherosclerosis; however, systemic inflammatory diseases such as rheumatoid arthritis, psoriasis, systemic lupus erythematosus and systemic sclerosis are also known risks for the development of atherosclerosis. Periodontitis, a local and systemic inflammatory condition, has also been reported as a risk for atherosclerosis, but the specific link between periodontitis and atherosclerosis remains somewhat controversial. We previously reported that ligature­induced periodontitis exacerbates atherosclerosis in hyperlipidemic Apolipoprotein E­deficient (ApoE­/­) mice. To understand whether hyperlipidemia is necessary for the development and exacerbation of atherosclerosis associated with periodontitis, the present study created ligature­induced periodontitis in both wild­type (WT) and ApoE­/­ mice. Subsequently, the status of local, systemic and vascular inflammation, serum lipid contents and arterial lipid deposition were examined with histological analysis, µCT, en face analysis, serum lipid and cytokine measurements, reverse transcription­quantitative PCR and immunohistochemical analysis. Ligature placement induced severe periodontitis in both WT and ApoE­/­ mice at the local level as demonstrated by gingival inflammation, alveolar bone loss, increased osteoclastic activities and inflammation in alveolar bone. Systemic inflammation was also induced by ligature placement in both WT and ApoE­/­ mice, albeit more so in ApoE­/­ mice. The serum cholesterol levels were not altered by the ligature in both WT and ApoE­/­ mice. However, the vascular inflammation and arterial lipid deposition were induced by ligature­induced periodontitis only in ApoE­/­ mice, but not in WT mice. The present study indicated that the coupling of systemic inflammation and hyperlipidemia was necessary for the development and exacerbation of atherosclerosis induced by ligature­induced periodontitis in mice.

The Effect of the Amnion-Chorion or Collagen Membrane as a Matrix on the Microenvironment During a Regenerative Endodontic Procedure.

INTRODUCTION: During regenerative endodontic procedures, the microenvironment of the canal is formed by the degree of disinfection and release of ions from the applied materials onto the top surface. This study aimed to characterize the effects of amnion-chorion membrane and collagen membrane on pulp-dentin regeneration compared to calcium silicate cements (CSCs), focusing on cell migration, mineralization potential, anti-inflammation, and angiogenesis. METHODS: Two CSCs and 2 membranes were used: ProRoot MTA (Dentsply, Tulsa, OK, USA), RetroMTA (BioMTA, Seoul, Korea), Collagen Membrane (Genoss, Suwon, Korea), and BioXclude (amnion-chorion membrane; Snoasis Medical, Colorado, USA). Transwell and scratch assays were used to evaluate cell migration and wound healing. Mineralization potential was evaluated using alkaline phosphatase activity, Alizarin red S staining, and quantitative real-time polymerase chain reaction for the expression of marker genes. Quantitative real-time polymerase chain reaction was used to measure the levels of angiogenic genes and inflammatory mediators. An endothelial tube formation assay was used to assess angiogenesis. RESULTS: The membranes showed superior migration and wound healing compared with CSCs. Except for RetroMTA, ProRoot MTA and the 2 membranes showed high alkaline phosphatase activity and mineralization nodule formation and upregulated mRNA expression of markers for mineralization. Membranes upregulated the mRNA of angiogenesis genes and increased the capillary tube formation of endothelial cells compared to CSCs. Furthermore, the membrane matrix decreased the expression of inflammatory genes. CONCLUSIONS: Collagen membrane and Amnion-chorion membrane showed prominent cell migration, angiogenesis, and healing effects against inflammation, as well as comparable mineralization potential compared to CSCs, recommending the use of membrane as a matrix.

Cytotoxicity and Genotoxicity of Epoxy Resin-Based Root Canal Sealers before and after Setting Procedures.

Epoxy resin-based sealers are commonly used for successful endodontic treatment. This study aimed to evaluate the cytotoxicity and genotoxicity of epoxy resin-based sealers under unset and set conditions. Three epoxy resin-based sealers were used: Adseal, AH Plus, and Dia-Proseal. To test cytotoxicity, an agar overlay test and a 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay were performed using unset and set sealers on L929 mouse fibroblasts. The genotoxicity test of the comet assay was performed using the same cell line. Extract dilutions in the culture media were used as test materials for the MTT and comet assays. The comet tail produced by the damaged DNA was calculated by image analyses. Statistical analyses were performed using one-way analysis of variance and Tukey's post hoc test. Unset sealers did not show defined decolorized areas. Hardened specimens of resin-based sealers showed circular discolored zones in the agar overlay test. Dia-Proseal was the least cytotoxic after hardening. These results were confirmed in the MTT assay. Cell viability was significantly higher in cells treated with hardened sealers in both groups than that in cells treated with freshly mixed sealers in the MTT assay. Unset AH Plus® and Dia-Proseal™ significantly increased cell viability with decreasing dilution. Adseal™ was the least cytotoxic. Freshly mixed Adseal™ was more genotoxic when freshly mixed than when set. Unset epoxy resin-based sealers were generally more cytotoxic and genotoxic than set materials. Cytotoxicity does not always match the genotoxicity results; therefore, various test tools are required to test toxicity. It is necessary to properly evaluate the toxic effects to establish a biocompatibility test that mimics clinical conditions.

Effects of Fucoidan Powder Combined with Mineral Trioxide Aggregate as a Direct Pulp-Capping Material.

The development of direct pulp-capping materials with favorable biological and structural properties is an important goal in restorative dentistry. Fucoidan is a sulfated, fucose-containing polysaccharide obtained from brown seaweed, with a wide range of applications; however, its use as a direct pulp-capping material has not been examined. This study aimed to evaluate the mechanical, physical, and biological effects of fucoidan combined with conventional mineral trioxide aggregate (MTA) for direct pulp capping. The capping materials were created using Portland cement (80 wt%) and zirconium oxide (20 wt%) as base components, compared with base components plus 5 wt% fucoidan (PZF5) and base components plus 10 wt% fucoidan (PZF10). The initial and final setting time, compressive strength, chemical components, cell viability, adhesion, migration, osteogenesis, and gene expression were analyzed. Fucoidan significantly reduced the initial and final setting time, regardless of quantity. However, the compressive strength was lower for PZF5. Sulfur levels increased with fucoidan. The biological activity improved, especially in the PZF5 group. Cell migration, Alizarin Red S staining, and alkaline phosphatase activity were upregulated in the PZF5 group. Fucoidan is a useful regenerative additive for conventional pulp-capping materials because it reduces the setting time and improves cell migration and osteogenic ability.

Topical application of Porphyromonas gingivalis into the gingival pocket in mice leads to chronic­active infection, periodontitis and systemic inflammation.

Porphyromonas gingivalis (Pg), one of the 'red­complex' perio­pathogens known to play a critical role in the development of periodontitis, has been used in various animal models to mimic human bacteria­induced periodontitis. In order to achieve a more realistic animal model of human Pg infection, the present study investigated whether repeated small­volume topical applications of Pg directly into the gingival pocket can induce local infection, including periodontitis and systemic vascular inflammation in wild­type mice. Freshly cultured Pg was topically applied directly into the gingival pocket of the second molars for 5 weeks (3 times/week). After the final application, the mice were left in cages for 4 or 8 weeks and sacrificed. The status of Pg colony formation in the pocket, gingival inflammation, alveolar bone loss, the expression levels of pro­inflammatory cytokines in the serum and aorta, the presence of anti­Pg lipopolysaccharide (LPS) and gingipain (Kpg and RgpB) antibodies in the serum, as well as the accumulation of Pg LPS and gingipain aggregates in the gingiva and arterial wall were evaluated. The topical application of Pg into the gingival pocket induced the following local and systemic pathohistological changes in mice when examined at 4 or 8 weeks after the final topical Pg application: Pg colonization in the majority of gingival pockets; increased gingival pocket depths; gingival inflammation indicated by the increased expression of TNF­α, IL­6 and IL­1ß; significant loss of alveolar bone at the sites of topical Pg application; and increased levels of pro­inflammatory cytokines, such as TNF­α, IL­1ß, IL­17, IL­13, KC and IFN­Î³ in the serum in comparison to those from mice receiving PBS. In addition, the Pg application/colonization model induced anti­Pg LPS and gingipain antibodies in serum, as well as the accumulation of Pg LPS and gingipain aggregates in the gingivae and arterial walls. To the best of our knowledge, this mouse model represents the first example of creating a more sustained local infection in the gingival tissues of wild­type mice and may prove to be useful for the investigation of the more natural and complete pathogenesis of the bacteria in the development of local oral and systemic diseases, such as atherosclerosis. It may also be useful for the determination of a treatment/prevention/efficacy model associated with Pg­induced colonization periodontitis in mice.

Evaluation of Tensile Bond Strength between Self-Adhesive Resin Cement and Surface-Pretreated Zirconia.

The tensile bond strength between zirconia subjected to different surface-pretreatment methods and methacryloyloxydecyl-dihydrogen-phosphate (MDP)-containing self-adhesive resin cement was evaluated herein. Eighty-eight cylindrical zirconia specimens were randomly divided into the following four groups based on the pretreatment method: (1) no treatment, (2) air abrasion, (3) HNO3/HF etching, and (4) zirconia-nanoparticle coating. The tensile bond strength of the zirconia−resin-cement complexes was investigated. One-way ANOVA and post hoc tests were performed at a 95% significance level, and the Weibull modulus was calculated. Fracture patterns were visualized by SEM. The surface roughness of the specimens without resin bonding was evaluated by AFM. The tensile bond strength of the specimens decreased as follows: Groups 3 > 4 > 2 > 1 (28.2 ± 6.6, 26.1 ± 5.7, 16.6 ± 3.3, and 13.9 ± 3.0 MPa, respectively). Groups 3 and 4 had significantly higher tensile bond strengths (p < 0.05) and lower fracture probabilities than those of Groups 1 and 2. They also showed both mixed failure and resin-cement cohesive failure, whereas Groups 1 and 2 showed mixed failure exclusively. The zirconia−resin tensile bond was stronger after HNO3/HF etching or ZrO2-nanoparticle coating than after air abrasion or no treatment. The estimated surface roughness decreased as follows: Groups 3 > 4 > 2 > 1. The combination of zirconia pretreated with HNO3/HF etching or ZrO2-nanoparticle coating and an MDP-containing self-adhesive resin cement can increase the clinical longevity of zirconia restorations by preventing their decementation.

Long-Term Ligature-Induced Periodontitis Exacerbates Development of Bisphosphonate-Related Osteonecrosis of the Jaw in Mice.

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a detrimental intraoral lesion that occurs in patients with long-term or high-dose use of anti-resorptive agents such as bisphosphonates. Tooth extraction is a known risk factor for BRONJ, and such intervention is often performed to eliminate existing pathological inflammatory conditions. Previously, we determined that ligature-induced periodontitis (LIP) is a risk factor for the development of osteonecrosis in mice, but it remains unclear whether the chronicity of LIP followed by extraction influences osteonecrosis development. In this study, we assess the effect of short-term and long-term LIP (ligature placed for 3 weeks [S-LIP] or 10 weeks [L-LIP], respectively) on osteonecrosis development in mice receiving 250 µg/kg/week zoledronic acid (ZOL). When compared to S-LIP, L-LIP caused 70% (p ≤ 0.0014) more bone loss without altering microbe composition. In the presence of ZOL, bone loss mediated by LIP was prevented and bone necrosis was induced. When the ligated tooth was extracted, histologic hallmarks of osteonecrosis including empty lacunae and necrotic bone were increased by 88% (p = 0.0374) and 114% (p = 0.0457), respectively, in L-LIP compared to S-LIP. We also observed significant increases in serum platelet factor 4 (PF4) and macrophage inflammatory factor 1 γ (MIP1γ) in mice that received ZOL treatment and had tooth extractions compared to controls, which may be systemic markers of inflammation-associated osteonecrosis development. Additionally, CD3+ T cells were identified as the major immune population in both health and disease, and we observed a 116% (p = 0.0402) increase in CD3+IL23R+ T cells in L-LIP compared to S-LIP lesions following extraction. Taken together, our study reveals that extracting a periodontally compromised tooth increases the formation of necrotic bone compared to extracting a periodontally healthy tooth and that osteonecrosis may be associated with the duration of the preexisting pathological inflammatory conditions. © 2022 American Society for Bone and Mineral Research (ASBMR).

Epithelial cells release IL-36α in extracellular vesicles following mechanical damage.

The epithelium is an integral part of barrier tissues, and plays a critical role in the initiation of the innate immune responses. The pro-inflammatory cytokine IL-36α has been previously reported to be strongly expressed during oral mucosal wound healing, but regulation of IL-36α expression and secretion in the oral mucosa are not well known. The objective of this study was to determine the types of stimuli that lead to expression and secretion of IL-36α in epithelial cells. Maxillary tissues from C57BL/6J mice during wound healing were utilized to identify endogenous expression of IL-36α, ß, and γ in oral epithelial tissue. Immortalized HaCaT cells and primary normal human oral keratinocytes were subjected to Escherichia coli derived lipopolysaccharide (LPS), Poly(I:C), heat killed Candida albicans (HKCa), and mechanical damage. IL-36α and IL-1ß levels in supernatant were assessed by sandwich ELISA, and expression of pro-inflammatory cytokines and IL-36 family genes were assessed by quantitative real-time PCR in HaCaT cells. Migration ability of keratinocytes was assessed with or without functional IL-36 signaling. IL-36α but not IL-36ß or γ levels in the oral epithelium were elevated during wound healing. Treatment of epithelial cells with LPS, Poly(I:C), HKCa and mechanical damage revealed little to no soluble IL-36α in the media supernatant. However, sonication of the supernatant to disrupt the membranes of extracellular vesicles revealed a dose-dependent increase in IL-36α for each of the tested conditions. IL-1 superfamily genes were upregulated following mechanical damage in keratinocytes. Abrogation of IL-36 signaling led to severe inhibition of migration. Our data show for the first time that IL-36α is released primarily in extracellular vesicles by oral keratinocytes. Additionally, we show that IL-36α - but not IL-36ß or γ - is upregulated in keratinocytes following mechanical damage, and that IL-36 signaling is important for keratinocyte migration.

Indigenous microbiota protects development of medication-related osteonecrosis induced by periapical disease in mice.

Bacterial infection is a common finding in patients, who develop medication-related osteonecrosis of the jaw (MRONJ) by the long-term and/or high-dose use of anti-resorptive agents such as bisphosphonate (BPs). However, pathological role of bacteria in MRONJ development at the early stage remains controversial. Here, we demonstrated that commensal microbiota protects against MRONJ development in the pulp-exposed periapical periodontitis mouse model. C57/BL6 female mice were treated with intragastric broad-spectrum antibiotics for 1 week. Zoledronic acid (ZOL) through intravenous injection and antibiotics in drinking water were administered for throughout the experiment. Pulp was exposed on the left maxillary first molar, then the mice were left for 5 weeks after which bilateral maxillary first molar was extracted and mice were left for additional 3 weeks to heal. All mice were harvested, and cecum, maxilla, and femurs were collected. ONJ development was assessed using µCT and histologic analyses. When antibiotic was treated in mice, these mice had no weight changes, but developed significantly enlarged ceca compared to the control group (CTL mice). Periapical bone resorption prior to the tooth extraction was similarly prevented when treated with antibiotics, which was confirmed by decreased osteoclasts and inflammation. ZOL treatment with pulp exposure significantly increased bone necrosis as determined by empty lacunae and necrotic bone amount. Furthermore, antibiotics treatment could further exacerbate bone necrosis, with increased osteoclast number. Our findings suggest that the commensal microbiome may play protective role, rather than pathological role, in the early stages of MRONJ development.