Publications by authors named "Regina Messer"

Purpose/objectives: Critical thinking and evidence-based dentistry are skills that dental students are required to demonstrate, but monitoring and quantifying progress can be challenging. This study is investigating whether the HEIghten critical thinking assessment (HCTA) could be used as a potential tool, both for use prior to admitting students, and to monitor whether the students' skills improve over their time at dental school.

Methods: Freshman dental students (n = 92) were given the HCTA during their first semester of dental school.

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The American Academy of Pediatric Dentistry (AAPD) affirms that the use of fluoride, as an adjunct in the prevention of caries, is safe and effective. The AAPD encourages dentists, other healthcare providers, and parents to optimize fluoride exposures to reduce the risk of caries and to enhance the remineralization of affected teeth. However, there is resistance amongst patients towards fluoride overexposure and despite there being research on other effective remineralizing agents, most pediatric dentists primarily cater their practice to fluoride-based products.

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Introduction: Fibroblasts are the dominant stromal cells in the gingival lamina propria with a well-established relevance in regulation of inflammation, and in innate immunity. This is exemplified by their hypersecretion of CXCL8, enhancing leukocyte infiltration in chronic and sustained inflammatory conditions. We have previously shown adenosine to be a key metabolic nucleoside that regulates stromal inflammation, but the underlying mechanisms linking adenosine to the metabolic status of fibroblasts and to the resultant inflammatory response are unclear.

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Corrosion and release of nickel ions from biomedical alloys are well documented, but little is still known about the effects of released nickel ions on cellular function with recurrent inflammatory challenges. Evidence suggests Ni(II) ions amplify LPS-induced secretion of several pro-inflammatory cytokines from monocytes. Exacerbating the inflammatory response, hyperglycemic conditions also affect monocytic function.

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Objective: The mandible is continuously undergoing remodeling as a result of mechanobiologic factors, such as chewing forces, tooth loss, orthodontic forces, and periodontitis. The effects of mechanical stress and biologic signals in bone homeostasis have been the focus of many investigations. However, much of this research utilized osteocytes derived from long bones, but little is known about the mandible-derived osteocytes.

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Objectives: The objective of this study was to evaluate the baseline differences between alveolar and basal areas of the rat mandible.

Study Design: Rat mandibular alveolar and basal bones were evaluated using histology and micro-computed tomography to compare osteocyte number as well as bone density and architecture and polymerase chain reaction to measure gene expression levels.

Results: Micro-computed tomography data indicated that basal bone is denser and less porous than alveolar bone.

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Unlabelled: Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a serious skeletal complication associated with the long-term oral or intravenous use of nitrogen-containing bisphosphonates (N-BPs). Here, we investigated the effects of an ionic cocktail prepared from water-soluble microfibrous borate glass on neutralizing the inhibitory effects of two heterocyclic N-BPs, risedronate or zoledronic acid, on osteoclastogenesis, apoptosis of differentiated osteoclasts and osteoclast function. Cell growth and proliferation assays were first performed on RAW 264.

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Article Synopsis
  • This study developed a rat model of bisphosphonate-related osteonecrosis of the jaw (BRONJ) to better understand the condition, previously not reliably induced in animal studies.
  • A modified treatment approach using a specific bisphosphonate dosage and repeated dental extractions resulted in all treated rats developing severe BRONJ, meeting clinical criteria for the condition in humans.
  • The findings showed that significant bone necrosis could occur without the need for pre-existing infections or other health issues, paving the way for further research on BRONJ's causes and prevention.
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Background: Recent studies suggest that light in the UVA range (320-400 nm) activates signaling pathways that are anti-inflammatory, antioxidative and play a critical role in protection against cancer. These effects have been attributed to NF-E2-related factor (NRF2)-mediated up-regulation of 'phase 2' genes that neutralize oxidative stress and metabolize electrophiles. We had previously shown that small doses of blue light (400-500 nm) had selective toxicity for cultured oral tumor cells and increased levels of peroxiredoxin phase 2 proteins, which led to our hypothesis that blue light activates NRF2 signaling.

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Long-term use of intravenous bisphosphonates, such as zoledronic acid (zoledronate), has been linked to bisphosphonate-related osteonecrosis of the jaw (BRONJ). Invasive dental surgery seems to trigger the bone necrosis in most cases. To determine the effects of zoledronic acid on the vascular structure of the rat mandible.

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Aim: Test whether human periodontal ligament fibroblasts (PDLFs) retain homeostatic responses to a physiological compressive force during chronic periodontitis.

Material And Methods: Six cell lines were established from periodontally healthy individuals (H-PDLFs) and another six were cultured from patients diagnosed with chronic periodontitis (D-PDLFs). Compressive force at 150 psi was applied to H-and D-PDLFs for 3 h on 2 consecutive days.

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The in vitro cytotoxic response to endodontic sealers was assessed for one year. AH-Plus (AHP), Epiphany (EPH), EndoRez (ER), Guttaflow (GF), InnoEndo (IN), and Pulp Canal Sealer (PCS) were exposed to mouse osteoblasts and human monocytes after curing, 52 weeks of aging, and after resurfacing post-aging; cellular response was estimated by succinate dehydrogenase (SDH) activity. The effect of materials on TNFα secretion from activated (LPS) and inactivated monocytes also was measured.

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Introduction: Quick-setting calcium aluminosilicate cement with improved washout resistance is a potential substitute for calcium silicate cements in endodontics. This study examined the effect of an experimental calcium aluminosilicate cement (Quick-Set; Primus Consulting, Bradenton, FL) on the viability of odontoblast-like cells.

Methods: The biocompatibility of Quick-Set and white ProRoot MTA (WMTA; Dentsply Tulsa Dental Specialties, Tulsa, OK) cements and their eluents was evaluated using a murine dental papilla-derived odontoblast-like cell line (MDPC-23); 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used to examine the effects of the 2 hydraulic cements on mitochondrial metabolic activity.

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The design of antimicrobial polymers to address healthcare issues and minimize environmental problems is an important endeavor with both fundamental and practical implications. Quaternary ammonium silane-functionalized methacrylate (QAMS) represents an example of antimicrobial macromonomers synthesized by a sol-gel chemical route; these compounds possess flexible Si-O-Si bonds. In present work, a partially hydrolyzed QAMS co-polymerized with 2,2-[4(2-hydroxy 3-methacryloxypropoxy)-phenyl]propane is introduced.

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A bioreactor system was developed to provide high-amplitude cyclic hydrostatic compressive stress (cHSC) using compressed air mixed commercially as needed to create partial pressures of oxygen and carbon dioxide appropriate for the cells under investigation. Operating pressures as high as 300 psi are achievable in this system at cyclic speeds of up to 0.2 Hz.

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Recent studies have reported that sealers may alter the secretion of specific cytokines from THP1 monocytic cells in vitro. In this study, a cytokine array was used to determine if endodontic sealers changed secretion of 42 cytokines. White mineral trioxide aggregate (WMTA), MTA preparation (CS), AH-Plus (AHP), and Pulp Canal Sealer (PCS) were mixed, allowed to set for 72 h, then "aged" in buffered-saline for 12 weeks.

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The in vitro cytotoxicity of five endodontic sealers was measured >8-12 weeks using L929 mouse fibroblasts, osteoblastic cells (ROS) 17/2.8 rat osteoblasts, and MC3T3-E1 mouse osteoblasts. Discs (n = 6) of AH-plus Jet (AHP), two versions of Endo Rez (ER, ERx), Epiphany (EPH), and Pulp Canal Sealer (PCS) were prepared.

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Objective: This in vitro study compared the cytotoxicity and osteogenic potential of an experimental calcium silicate-based sealer with an epoxy resin-based sealer (AH Plus; Dentsply Caulk, Milford, DE) and a zinc oxide-eugenol-based sealer (Pulp Canal Sealer; SybronEndo, Orange, CA).

Methods: Disks prepared from the respective sealer and from Teflon (negative control) were placed in direct contact with a MC3T3-E1 osteogenic cell line at 6 weekly intervals after immersion in a culture medium. Succinic dehydrogenase activities were evaluated using 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay.

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Background: In healthy periodontal tissue, innate immune responses effectively confine and suppress a bacterial insult. However, a disruption of the host-bacterial equilibrium may produce an overexpression of cytokines and lead to permanent, host-mediated tissue damage. Although such periodontal destruction primarily results from activated immune mechanisms, the site-specific damage suggests that local tissues participate in these pathologic changes.

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Few published studies describe the biological properties of calcium phosphate cements (CPCs) for dental applications. We measured several biologically relevant properties of 3 CPCs over an extended (8 wk) interval. Monocalcium phosphate, calcium oxide, and synthetic hydroxyapatite were combined with either modified polyacrylic acid, light-activated modified polyalkenoic acid, or 35% w/w polymethyl vinyl ether maleic acid to obtain Types I, II, and III CPCs, respectively.

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Endosseous dental implants use is increasing in patients with systemic conditions that compromise wound healing. Manufacturers recently have redesigned implants to ensure more reliable and faster osseointegration. One design strategy has been to create a porous phosphate-enriched titanium oxide (TiUnite) surface to increase surface area and enhance interactions with bone.

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Background: Current therapeutic approaches to salivary gland cancer are often associated with severe disfigurement and loss of glandular function, which are traumatic to the patients. Exploration of novel treatment approaches, such as gene therapy, is needed.

Materials And Methods: The human salivary gland cancer cell line HSG was transiently transfected with full length human caspase-14 cDNA.

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Metal-based drugs are largely undeveloped in pharmacology. One limiting factor is the systemic toxicity of metal-based compounds. A solid-phase, sequestratable delivery agent for local delivery of metals could reduce systemic toxicity, facilitating new drug development in this nascent area.

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Titanates are inorganic compounds with high affinity for specific metal ions or metal compounds, including gold. We have previously demonstrated that both monosodium titanate (MST) and amorphous peroxo-titanate (APT) alone do not suppress cellular metabolism of several cell types, and we have shown that MST and APT adsorb and release gold compounds in biological salt solutions. In the current study, we extend this work and show that MST and APT loaded with two gold compounds deliver sufficient levels of these compounds to alter the metabolism of mammalian cells.

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Dental endodontic sealers are in intimate contact with tissues around the root apex (periapical area) for extended periods. New endodontic sealers have been developed in the past decade, but the biological responses to many new products are not well documented. In this study, we assessed in vitro monocytic cytotoxic and inflammatory responses to several contemporary endodontic sealers.

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