• Biocompatibility and mechanical/physical properties of 3D printed, milled, and conventionally processed denture base materials

      Ulmer, Mallory; Biomedical Sciences (Augusta University, 2019-12)
      According to the American College of Prosthodontists, over 36 million people in the USA are edentulous with a 2:1 predilection for geriatric patients1. Each year, an estimated 15% of edentulous Americans will seek denture treatment1. Conventional dentures require multiple visits and lab processing time. 3D printing technology offers the potential to reduce the number of appointments and speed up the time until patient rehabilitation. However, the newly FDA-certified 3D printer denture resins, featuring secretive and proprietary formulae, lack studies concerning their biocompatibility/safety and mechanical strength. This study aims to investigate the biocompatibility and physical properties of one such 3D printer resin, NextDent® Base (Vertex, Soesterberg, The Netherlands), and compare it to pre-existing conventional polymethyl methacrylate (PMMA) denture base (Lucitone 199, Dentsply Sirona, York, Pennsylvania) and milled PMMA denture base (IvoBase CAD®, Ivoclar Vivadent AG, Schaan, Liechtenstein). The cytotoxicity was examined using of 12 discs: conventional PMMA, milled PMMA, as-printed 3D printer resin, post-cured 3D printer resin, and Teflon controls. An MTT assay using human periodontal ligament (900L) cells was employed, and specimens were aged for 1, 3, 7, 10, and 14 days. After day 7, there were no statistically significant differences among the groups, excluding the Teflon control, which showed significantly less cell viability on day 14. Bars of conventional PMMA, milled PMMA, as-printed 3D printer resin, and post-cured 3D printer resin were subjected to a 3-point bend test to examine flexural strength and moduli differences. The mean flexural strength was 63.8 ± 3.06, 82.6 ± 1.9, 5.1 ± 0.4, and 22.1 ± 6.4 MPa, respectively, while the flexural moduli were 1757.3 ± 109.5, 2226.7 ± 76.3, 110.3 ± 20.3, and 537.0 ± 210.6 MPa, respectively. The flexural strength and modulus were significantly different among all groups. Weibull analyses for conventional PMMA, milled PMMA, as-printed 3D printer resin, and post-cured 3D printer resin revealed a Weibull modulus of 23.5, 42.8, 16.6, and 3.7, respectively, and a characteristic strength of 65.2, 83.5, 5.3, and 24.5 MPa, respectively. The characteristic strength was significantly different among all groups as well. The Weibull modulus was significantly different between all groups, except for conventional vs. as-printed, which were not significantly different. In summary, milled PMMA featured significantly greater mechanical properties. Both 3D printed groups proved to be very weak, with the as-printed group being the weakest of all. The differences between the as-printed and post-cured groups highlight the importance of properly post-curing the resin. While the biocompatibility results showed promise, the mechanical testing results were disappointing. Unfortunately, the findings suggest that 3D-printed denture base resin is not yet ready for clinical use.
    • The Effect of Nrf2 on Inflammatory Responses of Human Monocytic Cells After Blue Light Exposure

      Trotter, Leigh Ann; Trotter, Leigh Ann; Department of Oral Biology (12-Apr)
      Blue light treatment alters cellular signaling and affects intracellular biochemical processes in tissues. PURPOSE: This study determined the ability of blue light to modulate Nrf2 and decrease LPS-induced secretion of pro-inflammatory cytokines from cultured, human monocytic cells. METHODS: Cultured THP-1 human monocytic cells were exposed to LPS and blue light treatment. Western Blot analyses, EMSA, and ELISA were used to evaluate NF?B, Nrf2, HO-1, TNF-?, IL-6 and IL-8 production. RESULTS: Light treatment increased nuclear Nrf2 and increased HO-1. Cells pretreated with light had no detectable NF?B-DNA binding. LPS treatment increased nuclear NF?B, and had little effect on Nrf2. Light pre-treatment significantly decreased the amount of TNF-? by 63% and IL-8 by 55%. CONCLUSIONS: Blue light increases the production of Nrf2 and HO-1, decreases the ability of Nf?B to bind in the nucleus, and leads to a decrease in the secretion of pro-inflammatory proteins in human monocytic cells.
    • The role of Toll-like receptor (TLR) 2 in the systemic immune response profile of mice induced to develop squamous cell carcinoma of the upper aerodigestive tract

      El-Shafey, Sally; El-Shafey, Sally; Department of Oral Biology (4/1/2017)
      Background Head and necksquamous cell carcinomais associated with immunosuppression, a state in which the progression of cancer is associated with disturbances in the immune system functions. Emerging studies suggest a fundamental role for the innate immune system, particularly Toll-like receptor 2 (TLR2), in this process.QuestionsIn this study, we investigated the potential roles of TLR2 on systemic immune profile in a mouse model of headand necksquamous cell carcinoma.MethodsTwo different protocols of a mouse model of 4-nitroquinoline 1-oxide and ethanol-induced carcinogenesis to induce head and neck squamous cell carcinoma were used. To evaluate the systemic immune profiles, total RNA wasisolated from the spleens of four groups of animals, including carcinogen-treated and control untreated wild-type and toll-like receptor 2-deficient animals. Quantitative real-time PCR was performed forgenesrepresentative of house-keeping genes, type 1 and type 2 immune responses, regulatory T and B cells, and adenosine receptors.Results and ConclusionIn the standard protocol of 4-nitroquinoline 1-oxide and ethanol-induced carcinogenesis, there was asignificant upregulation of adenosine receptor A2a in the spleens of wild type iiimice treatedwith4-nitroquinoline 1-oxide and ethanolrelative to wild type untreatedanimals. In the standard protocol of carcinogenesis, there was a significant upregulation of CD39 in the spleens of TLR2-koanimalstreated with 4-nitroquinoline 1-oxide and ethanol relative to untreated TLR2-ko mice. These results suggest that carcinogenesis in the upper aerodigestive tract is associated with alterations in the systemic immune profile reflected in the spleen. However, the specific impact on the immune profiles appears to be affected by the presence or absence of TLR2.

      Elzinga, Jennifer Lynn; Department of Oral Biology (2/1/2013)

      Abraham, Pheba; Abraham, Pheba; Department of Oral Biology (5/1/2017)
      This study was to explore the effect of local, matrix-bound bisphosphonates to monocytedifferentiation and osteoclast function in vitro. Experiments were designed using osteoassay plates. Cell-viability, differentiation, resorption pits and gene expression were analyzed to see the effect of matrix-bound BPs on monocyte differentiation and osteoclast function. EDTA was used as a chelating agent to remove the bound BPs. There was a dose dependent response in the differentiation and resorption pits. With chelation, there was increase in differentiation, resorption pits and increase in the calcium and PYD in the supernatant. Thus, matrix-bound Bisphosphonatesare biologically active and they inhibit monocyte differentiation and osteoclast function. Thereby removal of this matrix-bound drug can rescue osteoclast differentiation and function.
    • Inherent Gene Expression and Protein Profile Differences Between Alveolar and Basal Bone

      Alotaibi, Fawwaz; Alotaibi, Fawwaz; Department of Oral Biology (5/1/2015)
      The mandible is composed to two bone types: alveolar and basal. Previous studies on the mandible have shown that the alveolar bone resorbs more than the basal bone after tooth extraction or as a result of tooth movement. Reasons for why the resorption rates are different is not well understood. This research begins exploring the differences of the alveolar and basal bone by using comparison characteristics such as bone mineral density (BMD), gene expression, protein profiles, and number of osteocytes. The research investigates these characteristics by using Real time RCR to study the differences in gene expression and protein profiles of the alveolar and basal bone. Micro-CT was used in comparing density and bone architecture characteristics of the alveolar and basal bone. Immunohistochemistry was used to better understand how osteocytes are different between the two bone types in hopes of later being able to understand the differences in resorption rates. The real time PCR showed that four genes are expressed significantly higher in basal bone than alveolar bone: SOST, E-11, DMP-1, MEPE. Three of which are associated with mature osteocytes indicating that basal bone has more mature osteocyte phenotypes. Micro-CT data indicated that the basal bone is denser and less porous than alveolar bone. There was no significant difference in immunohistochemistry and further quantitative testing is needed to draw and significant correlation.

      Thakkar, Parth; Department of Biological Sciences; Department of Oral Biology; Teng, Yong; Augusta University (2019-02-13)
      More than 90% of head and neck cancer is head and neck squamous cell carcinoma1 (HNSCC). Currently, the treatment involves modern surgery, conventional chemotherapy, and radiation. However, targeting, the epidermal growth factor receptor (EGFR) has been shown to prove advantageous for patient survival. EGFR activation leads to cell cycle progression. Blocking the EGFR by an antibody results in the inhibition of the receptor, therefore inhibition of cell proliferation. This makes EGFR a prime target for anticancer therapy, specifically with tyrosine kinase inhibitors being looked at as a possible form of inhibition. The goal of this project was to hopefully use small molecule inhibitor EXO2 and an EGFR specific tyrosine kinase inhibitor, Erlotinib, in a synergistic manner to fight against HNSCC. This study was done using cell cultures, MTT assay�s and western blot techniques, with cell cultures being done using the H6 cell line. The results from this study were found to be a preliminary success and will pave the way for future experiments in this area.

      Sun, Christina; Awad, Mohamed E; Jernigan, Joshua; College of Science and Mathematics; Department of Oral Biology; Dental College of Georgia; Elsalanty, Mohammed; Augusta University (2019-02-13)
      The aim of this systematic review was to evaluate the validity of using preoperative serum C-terminal crosslinking telopeptide (CTX) levels as predictive factor of increased risk of developing medication-related osteonecrosis of the jaw (MRONJ) in patients on bisphosphonate (BP) therapy who undergo invasive dental procedures. A search was conducted through PubMed, MEDLINE, and Web of Science, following PRISMA guidelines and the Cochrane Handbook for Systematic Reviews of Interventions. Meta-analysis was conducted on the risk ratio. The methodological index for nonrandomized studies (MINORS) and Quality Appraisal of Reliability Studies (QAREL) checklist were used to assess quality. Eighteen clinical trials, involving 2301 patients were included. Most patients received Alendronate or Risedronate for an average of 62.14 months. The average serum CTX level in BP-treated patients before surgery was 217.67 pg/ml. Meta-analysis demonstrated that the cutoff in CTX level (150 pg/ml) was not predictive of BRONJ risk. The sensitivity of CTX value <150 pg/ml was 34.26% and the specificity was 77.08%. The use of CTX to diagnose BRONJ risk following dental procedures in bisphosphonate-treated patients is not justified. Further studies are needed to develop other reliable biomarkers.
    • Histology of the Dental Extraction Sites of Bisphosphonate Treated Rats

      Ferguson, Alisa; Department of Oral Biology (Augusta University, 2018-12)
      Bisphosphonate is a drug given to both men and women who are experiencing decreasing bone density and strength. When patients taking bisphosphonate undergo some sort of jaw trauma (i.e. tooth extraction, accident), they can experience necrosis or cell death of the jawbone. Our hypothesis is that bisphosphonate molecules bound to the bone matrix contribute to bone necrosis. For my thesis, a histological analysis of the mandibles from bisphosphonate treated rats after dental extraction with and without removal of bisphosphonates from the extraction site of the bone was done. Histological sections of the jaw from bisphosphonate treated rats after bilateral extraction of the first and second molar teeth were taken. On one side, the extraction site was treated with EDTA to chelate bisphosphonates from the bony wall of the tooth socket. The other side of the rat’s jaw was treated with Saline. I then evaluated the vitality of alveolar bone by counting the number of dead versus live osteocytes around the extraction site and comparing the ratios between the chelated and un-chelated sides from each rat. The study determined whether removal of localized bisphosphonates is beneficial to preserve bone vitality after dental extraction. As expected, the percentage of live osteocytes decreased in the alveolar bone of animals treated with Zoledronate (ZA), a strong dose of bisphosphonate. Furthermore, there was a trend of increased percentage of live cells when EDTA was used, although the differences were not statistically significant. These results support other studies in our laboratory that have shown that localized bisphosphonates play a role in the osteonecrosis associated with ZA treatment. It, therefore, provides evidence that localized bisphosphonates contribute to the etiology of bone necrosis in patients undergoing bisphosphonate treatment.
    • Effects of vitamin D supplementation on untreated chronic periodontitis

      Mogrovejo, Fernando; Master of Oral Biology (2016)
    • Marker Co-Expression Analysis of Initial Cellular Events in the Critical-Size Rat Calvarial Defect Model and the Effect of Bone Morphogenetic Protein-2 (rhBMP-2)

      Capetillo, Joseph F.; Department of Oral Biology (4/15/2016)
      Craniofacial defects can result from congenital malformations, trauma, tumor resection,periodontal disease, post-extraction ridge remodeling, and peri-implantitis. Regenerationof bone is critical to achieving functional and esthetic outcomes in the rehabilitation ofsuch defects. Traditional strategies for osseous regeneration include a multiple ofsurgical techniques utilizing autologous bone, cadaver-sourced allogeneic or xenogeneicbone, synthetic bone biomaterials, barrier membranes, or combinations thereof(Wikesjö, Qahash 2009). The need to enhance the predictability of regeneration inespecially large defects that cannot heal adequately without intervention (critical-sizedefects) has led to recent development of protein- and cell-based technologies.[Introduction, first paragraph]