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Founded in 1804, the University of Maryland School of Dentistry is the direct descendant of the world's first dental college, the Baltimore College of Dental Surgery (BCDS). The School's mission is to graduate exceptional oral health care professionals, contribute to the scientific basis of treatments for diseases of the orofacial complex, and deliver comprehensive dental care.
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Novel Bioactive Low-shrinkage-stress Nanocomposite with Antibacterial and Remineralization Properties and Thermal-cycling and Aging Resistance.Dental composites continue to be the material of choice in daily dental practice for several reasons, including their good mechanical properties, conservative cavity design, and superior esthetics. However, the longevity of current resin composite restorations ranges only 5-10 years. Recurrent caries and tooth fracture are the most common types of failure during the first 6 years of clinical service. These failures are often caused by the polymerization shrinkage stress of the dental composite materials. Thus, there is an increased need to develop a new generation of bioactive dental composite with the ability to reduce polymerization shrinkage stress, long-term antibacterial, remineralization abilities, and excellent mechanical properties. Therefore, this dissertation aims to develop a new bioactive low-shrinkage-stress dental composite containing dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP) which could be a promising approach to increase the chances of success of composite restorations and strengthen tooth structures. First, we found that the new bioactive low-shrinkage-stress resin composite significantly reduced the polymerization shrinkage stress, without compromising their mechanical properties. Increasing the DMAHDM mass fraction increased the antibacterial effect in a dose-dependent manner. Next, we investigated the low-shrinkage-stress composite mechanical stability and antibacterial durability in thermal cycling for 20,000 cycles, equivalent to two years of clinical life. We found that the bioactive low-shrinkage-stress composite possessed good mechanical properties that matched commercial composite both before and after thermal cycling. The new composite had potent antibacterial activity, which was maintained and did not decrease after thermal cycling. Lastly, we further examined the mechanical and antibacterial durability of a bioactive low-shrinkage-stress after 50,000 and 100,000 thermal cycles which corresponds to 5 and 10 years respectively of in vivo function. We found that the bioactive low-shrinkage-stress composite maintained its antibacterial potency after thermal cycling, indicating long-term antibacterial durability. In addition, it possessed good mechanical properties that were comparable to commercial composite both before and after thermal cycling. The triple benefits of antibacterial, remineralization, and lower shrinkage stress have a great potential to inhibit recurrent caries and increase restoration longevity.
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Soluble Immune Biomarkers as a Diagnostic Tool of Head and Neck Squamous Cell Carcinoma Histological Inflammatory SubtypesHead and neck squamous cell carcinoma (HNSCC) is a devastating malignancy that occurs in close proximity to vital structures. Despite all advances in diagnostic and therapeutic measures, the overall 5-year survival rate stays at ~65% and can be dismal for recurrent and advanced stages. There is accumulating evidence indicating the immune suppressive potential of HNSCC by which it can escape and/ or suppress the immune system. The recent advent of immunotherapy showed unprecedented improvement in overall response of advanced stage HNSCC. Yet, the overall response rate of HNSCC to immunotherapy remains at ~ 15%. Hence, further understanding of HNSCC tumor inflammation is warranted. The hypothesis of the current work is that the histological inflammatory subtype (HIS) of HNSCC can provide the basis for patient stratification that can be distinguished from the cytokine profile in peripheral blood, therefore better treatment strategies and patient outcomes. Paired tumor tissue and plasma of 104 HNSCC cases were collected according to UMB IRB protocol. Scoring of the HIS subtype was carried out using immunohistochemistry (IHC) of the emerging immune biomarker Semaphorin 4D (Sema4D). Our cohort showed 52% HIS inflamed (HIS-INF), 40% immune excluded (HIS-IE) and 8% deserted (HIS-ID). Differential gene expression (DGE) analysis of 10 HNSCC tumor tissues using NanoString immune-oncologic (human IO-360) 700 genes set showed that tumors with HIS-IE clustered as IFN-γ negative/ low immune signature compared to HIS-INF and were higher in hypoxia gene expression and the myeloid cellular compartment, while the HIS-INF demonstrated higher lymphoid component. DGE revealed a novel association between the high soluble Sema4D in plasma (HsS4D) and higher transcriptional level of Osteopontin (OPN) in the tumor tissue, that we also demonstrated in vitro. Furthermore, using ELISA-Luminex™ system, HIS-IE tumor tissue was significantly distinguished from the HIS-INF, in almost 40 traditional cytokines detected in the paired plasma samples. In conclusion, our work demonstrated a stratification model of HNSCC based on the underlying HIS profile that can be detected via the soluble cytokine panel in blood. These findings can open new avenues for patient stratification and enhance personalized clinical care in the field of HNSCC.
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The Trueness of additive and Subtractive Zirconia CrownsPurpose: To assess the trueness of ceramic crowns fabricated using additive technology compared to crowns fabricated using subtractive technology. Material and methods: single crown was designed using Dental Designer Software. 3D design was used to fabricate milled and printed crowns. All crowns were scanned. Geomagic software was used for analysis. Best Fit and Marginal Fit Alignment used to analyze the 3D accuracy of the crowns. One Way ANOVA used to analyze the data, and p<0.05 was considered significant. Result: Significant differences found between the additively and subtractive manufactured crowns [p=0.003,F=11.172]. Additively manufactured crowns exhibited better trueness than subtractive crowns. For the additively manufactured crowns, the Best fit Alignment showed 42.81±40.8μm deviation, and the Marginal Alignment showed a 43.11 ±38.05μm deviation. For Subtractive manufactured crowns, the deviation in Best Fit Alignment was 62.67 ±50.79μm and in Marginal Alignment was 55.35±48.69μm. Conclusion: Additive technology fulfills surface trueness criteria.
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Novel Bio-interactive Fixed Dental Restoration Cement with Potent Antibacterial and Remineralization PropertiesResin-based cement is increasingly used in clinical practice due to its excellent mechanical and physical properties. The cementation and accurate placement of fixed dental restorations with an ideal marginal adaptation to the tooth structure remains a challenging laboratory and clinical task. The marginal gap of fixed dental restoration increases the opportunity for microleakage, plaque accumulation, and tooth demineralization by increasing the potential for food buildup around the margin and exposing the tooth-cement interface to the oral cavity. Thus, there is an increased need to develop a new generation of bio-interactive dental cement with antibacterial, long-term remineralization abilities, and excellent mechanical properties. Therefore, this dissertation aims to invent new bio-interactive resin-based cement containing dimethylaminohexadecyl methacrylate (DMAHDM), nanoparticles of amorphous calcium phosphate (NACP), and nanoparticles of calcium fluoride (nCaF2), which could be a promising approach to increase the chances of success of fixed dental restoration and strengthen tooth structures. All new cement formulations were subjected to a series of mechanical, antibacterial, and ion release assessments. In the first manuscript, we found that the new NACP+DMAHDM cement has excellent potential for fixed restoration cementation, as it efficiently inhibited S. mutans biofilm commonly associated with secondary caries and maintained an excellent mechanical property with high levels of Ca and P ions released. In the second manuscript, we found that incorporating DMAHDM and NACP into resin-based cement provides strong antibacterial action against saliva microcosm biofilm and presents a high level of Ca and P ion recharge abilities. In the third manuscript, we found that the new cement with both NACP and nCaF2 demonstrated the advantages of both types of bio-interactive fillers as it could release a higher level of ions than the resin cement with only nCAF2 and exhibits a better rechargeability compared to the resin cement with only NACP. Lastly, in the fourth manuscript, we found that the novel antibacterial low-shrinkage-stress resin-based cement provided strong antibacterial action and maintained excellent mechanical properties with reduced polymerization shrinkage stress, which could improve the long-term success of the fixed dental restoration.
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Caries Experience Based on A Simulated Epidemiological Screening and Routine Examination with RadiographsPurpose: To assess and compare caries experience based on an epidemiological “screening” examination and a routine examination with radiographs. Methods: 128 patients ages 5 to 10 years were included. An initial examination was done by a pediatric dentist in conditions simulating an epidemiological screening assessment. A second evaluation was done by eight postgraduate pediatric dental resident who conducted a routine clinical exam of the patient in the dental chair including radiographs. Results: By the epidemiological screening, the prevalence of untreated dental caries (Y/N) in primary and/or permanent teeth was 50% and the caries experience was 77%. After the routine examination with radiographs, the prevalence of untreated dental caries was 74.22% and caries experience was 90%. The severity of untreated dental caries was 2.0 and 3.9, and the severity of caries experience was 3.2 and 5.6 by the simulated epidemiological screening and routine examination with radiographs, respectively.
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MDental 2022University of Maryland, Baltimore. School of Dentistry, 2022
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Alumni: Baltimore College of Dental Surgery, 1913-1916Photograph album of the Baltimore College of Dental Surgery Alumni and Faculty. The album dates from 1913-1916. Album is available in the Internet Archive, see link.
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Alumni: Baltimore College of Dental Surgery, 1901-1912Photograph album of the Baltimore College of Dental Surgery Alumni and Faculty. The album dates from 1901-1912. Album is available in the Internet Archive, see link.
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Alumni: Baltimore College of Dental Surgery, 1892-1900Photograph Album of the Baltimore College of Dental Surgery Alumni dated 1892-1900. The 1892 and 1893 class graduates have been identified. Album is available through the Internet Archive, see link.
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Alumni: Baltimore College of Dental Surgery, 1883-1891Photograph album of the Baltimore College of Dental Surgery Alumni and Faculty. The album dates from 1883 to 1891. Album is available in the Internet Archive, see link.
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Generational Perspectives of Orthodontists in the U.S. and Canada– A Survey StudyObjective: To identify differences between generations of orthodontists in the U.S. and Canada and to evaluate the perspective of each generation on widely debated topics in orthodontics. Materials and Methods: A 22-item IRB approved survey was distributed to orthodontists in the U.S. and Canada. Participants were asked questions about the use of technology, future of clear aligner therapy (CAT), orthodontic education, student debt, marketing, and corporate orthodontics among other topics. Results: Significant increase in female orthodontists over generations and a decrease in orthodontic educators was found (P<0.001). Among generations, differences were found in regard to their amount of student debt, use of specific diagnostic tools, marketing preferences, and their opinion on the future of CAT. Conclusions: Clear distinctions exist between different generations of orthodontists. Issues such as increasing student debt load and a decrease in orthodontic educators over generations should be addressed to preserve the future of the orthodontic profession.
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The role of Angiopoietin-like 4 in head and neck squamous cell carcinoma progression and disseminationDysregulation of cellular signaling is instrumental in the promotion of tumor cell metabolism, proliferation, tissue invasion and metastasis. Molecular-based therapies for neoplastic diseases are designed to modulate or interact with cell surface receptors, intracellular cascades, or microenvironment components related to the extracellular matrix, tumor vasculature and immune response. To design these therapies, an improved understanding of the molecular underpinnings leading to tumor growth is essential. The overall aim of our investigation is identification of the molecular mechanisms associated with the induction of tumor cell migration and proliferation induced by Angiopoietin-like 4 (ANGPTL4), a pro-tumorigenic and pro-angiogenic factor, in head and neck cancer squamous cell carcinoma (HNSCC). HNSCC accounts for around 54,000 new cases and 11,000 deaths per year in the United States. Unfortunately, the clinical management of this tumor remains challenging. Our studies, divided into two research aims, use in vitro cell-based models together with signal transduction and cell and molecular biology methods. Our results demonstrate that: 1) ANGPTL4 is upregulated in human-derived dysplastic oral keratinocytes (DOKs) and HNSCC cell lines, but not in normal oral keratinocytes (NOKs), suggesting an early and sustained role for ANGPTL4 in disease progression. ANGPTL4 is a molecular marker in biopsies from patients with mild-moderate or moderate oral epithelial dysplasia, primary HNSCC and metastatic HNSCC. ANGPTL4 is necessary and sufficient to promote cell migration in DOKs and HNSCCs lines. Binding of ANGPTL4 to neuropilin-1 (NRP1) leads to paxillin (PXN) phosphorylation and cell migration in an ABL1-dependent manner, exposing the ANGPTL4/NRP1/ABL1/PXN cascade as a vulnerable target for HNSCC treatment. 2) Epidermal Growth Factor (EGF)- and Hypoxia-inducible Factor-1 (HIF-1)-mediated pathways cooperate in the upregulation of ANGPTL4 in normal and dysplastic oral keratinocytes and HNSCC cells. Besides EGF, the EGF ligand amphiregulin leads to an increase in ANGPTL4 and is upregulated in HNSCC lesions. ANGPTL4 activates the HNSCC molecular markers p38 MAPK, AKT and mTOR in NOKs; these kinases may act as potential intracellular regulators of the autocrine signals and paracrine secretions that ANGPTL4 activates to promote HNSCC tumorigenesis. Collectively, our findings suggest that ANGPTL4 and its associated signaling molecules are potential therapeutic targets in HNSCC clinical management.
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Global Temporary Anchorage Device (TAD) Usage: A Survey of OrthodontistsObjective: We aim to determine how often TADs are used worldwide and establish guidelines for implementing TADs in everyday practice. Methods: A 19 question survey was sent to orthodontists around the world asking opinion based, case-specific, and placement technique questions regarding TADs. The country of practice and length of time practicing orthodontics were the independent variables. Results: Most orthodontists use TADs rarely/sporadically. There were significant findings for how TADs are being used, sizes, and placement techniques amongst different continents. There was a significant difference in how many TADs orthodontists placed in residency according to how long they have been practicing, but it did not greatly affect frequency of use, mechanics, or placement technique. Conclusion: The frequency of TAD use is similar worldwide and amongst different age groups. Although significant data was found in this study, there is such variability in regard to TADs that clear guidelines were not established.
