Now showing items 1-20 of 562

    • School of Dentistry Catalog 2018-2019

      University of Maryland, Baltimore. School of Dentistry, 2018
    • MDental 2019

      University of Maryland, Baltimore. Dental School, 2019
    • Therapeutic Evaluation of a Novel Topical Antimicrobial Formulation against Candida-Associated Denture Stomatitis in an Experimental Rat Model

      Sultan, Ahmed; Jabra-Rizk, Mary Ann; 0000-0001-5286-4562 (2019)
      Candida-associated denture stomatitis (DS), caused by the fungal species Candida albicans, is the most common manifestation of oral candidiasis and is prevalent in up to 70% of denture wearers. DS tends to be a persistent and recurrent oral condition as a consequence of the ability of C. albicans to adhere to denture material and invade associated palatal tissue. There are currently no effective therapeutic strategies targeting DS, and despite antifungal therapy, infection is often re-established after treatment ceases. Therefore, it has become crucial to identify novel therapeutic approaches. Antimicrobial peptides have attracted significant attention as candidates for drug development due to their potent antimicrobial and anti-inflammatory properties, lack of toxicity and lack of development of drug resistance. Specifically, histatin-5 (Hst-5), naturally produced and secreted by host salivary glands, has demonstrated potent antifungal activity, including against strains resistant to traditional antifungals. However, our laboratory has previously demonstrated vulnerability for Hst-5 to proteolysis by C. albicans secreted proteolytic enzymes at specific amino acid residues. Therefore, to generate a resistant derivative of Hst-5, we engineered a variant (K11R-K17R) with substitutions in the amino acid residues at the cleavage sites. The new peptide proved to be more stable, and unlike the native Hst-5, resistant to proteolysis by C. albicans proteases. Importantly, for clinical application, we designed a polymer-based bioadhesive hydrogel as a delivery system for the peptide and developed a therapeutic formulation specifically designed for oral topical application. The potency of the new formulation in inhibiting C. albicans adherence and biofilm formation on denture acrylic material was demonstrated in vitro indicating a potential clinical applicability against DS. To that end, using 3D digital design and printing technology, we engineered and fabricated a universal intraoral device that was successfully used in the animals to develop clinical disease mimicking DS as in humans. Using the novel animal model, we established the clinical utility of the formulation for the prevention of biofilm formation on denture device and DS development. Importantly, in addition to DS, the formulation can also be used for treatment of other forms of candidiasis as well as serve in augmenting host natural immune defenses.
    • The Effects of Glossectomy on Airway to Tongue Ratio and Mandibular Morphology Using MRI

      Kim, Eric J.; Stone, Maureen L. (2019)
      Purpose: This study asked if glossectomy surgery causes anatomical changes of the surrounding structures and the airway by altering the balance of forces in the oral cavity. We predict that glossectomy patients will have proportionately larger pharyngeal air spaces than controls relative to the hard and soft structures around the mandible. Materials and Methods: Twenty subjects were studied, ten T1 or T2 SCC glossectomies and ten controls. The gathered MRI data sets were reconstructed into 3D volumes. Results: Mid-sagittal transpalatal airway lengths were significantly shorter for the glossectomy subjects. All other measurements were not statistically significant between the two groups. Discussion: A person may compensate for the reduction of tongue size following glossectomy, which may contribute to a shorter A-P airway distance at the transpalatal level. However, all other tests were not statistically significant, including the transpalatal area inidicating that objects in the oral cavity adapt to the reduction in tongue size and does not affect the established equilibrium. The overall transpalatal airway size may be maintained in post-glossectomy speakers by lateral expansion of the airway at the transpalatal level. Conclusion: This study concluded that the spatial relationships between airway and oral structures may change in dimension, but not in balance of forces following glossectomy. Second conclusion was that a 3-dimensional imaging is required for evaluation of the airway.
    • Alveolar Bone Height Changes in Patients Treated with Conventional and Damon Brackets

      Akinwande, Akinwale Banji; Schneider, Monica, D.D.S., M.S. (2019)
      Objective: To compare the distance between the cementoenamel junction (CEJ) and marginal alveolar bone (MAB) on the buccal root surfaces of the maxilla and mandible after orthodontic treatment using Conventional bracket system (CS) and Damon bracket system (DS). Methods: The sample included 30 patients, 14- 46 years of age (13 treated with CB and 17 with DB) with moderate to severe crowding treated nonextraction. We compared pre and post-alignment cone beam computed tomography (CBCT) images to measure the bone height (BH) changes of 24 buccal surfaces for each subject. Results: Even though we found great variability in BH levels, there was a statistically significant difference (Paired t-test: p value ≤ 0.05) between pre and post- alignment CBCT images of teeth in both Conventional and Damon groups. There was no statistically significant difference (independent t-test: p value ≤ 0.05) in BH changes when comparing the 2 bracket systems. Conclusion: The bone height levels changed after orthodontic treatment with both Conventional and Damon bracket systems, but there appears to be no significant difference in alveolar bone height changes between the two brackets in this study.
    • The Effect of Malocclusion Severity and Treatment Duration on Patient Satisfaction with Clear Aligner Therapy

      Wiese, Lauren Elizabeth; Bosio, Jose A.; Williams, Robert E., D.M.D., M.A.; 0000-0003-0335-7606 (2019)
      Objective: Determine if a patient’s initial malocclusion and treatment duration influenced satisfaction with clear aligner (Invisalign®) therapy. Methods: Thirty-three orthodontic patients treated with clear aligners responded to a satisfaction questionnaire containing twenty-one questions relating to their satisfaction with treatment, approximately two years after completing treatment. Overjet, overbite, and maxillary and mandibular anterior crowding/spacing were measured to determine the initial severity of their malocclusion. Logistic regression analyses with satisfaction factors as the dependent variable were used to quantify associations between patient satisfaction regarding both the initial severity of malocclusion and treatment duration. Results: Overall, patients were satisfied with aligner treatment. However, no significant associations were observed between patient satisfaction and either the initial severity of the malocclusion or treatment duration. Conclusion: The current study does not find that initial malocclusion or treatment duration significantly affects patient satisfaction. Patient satisfaction with clear aligner therapy is generally very high, and multi-factorial.
    • A Comparison of the Levels of Salivary Biomarkers between Conventional Smokers and Electronic Cigarette Users (A Pilot Study)

      Faridoun, Afnan; Meiller, Timothy F. (2019)
      Cigarette smoking is known to alter host response and the release of inflammatory mediators and cytokines in the body. Electronic cigarettes were marketed to provide the same sensation of conventional smoking without detrimental health consequences; however, the safety of their use is an area where more research is needed. Utilizing saliva as a diagnostic medium has been rising, however, there is a lack of studies investigating the effect of e-cigarettes on the salivary biomarker profile. The purpose of this pilot project was to evaluate the salivary cytokines, associated with inflammation, and CRP profile in e-cigarette users, and compare that to cigarette smokers and controls in an attempt to assess the influence of the use of e-cigarettes on salivary biomarkers. Statistically significant elevated levels of IL- 1β accompanied by lower mean levels of IL-1RA in e-cigarette users were detected. TNF- α showed elevated values in e-cigarette users similar to conventional smokers.
    • Osteoblast Attachment, Proliferation and Differentiation on Implant Surfaces

      Choe, Robert; Masri, Radi, 1975- (2019)
      Introduction. Countless numbers of implants with different surface treatment techniques exist commercially around the world. Cell adhesion, proliferation and differentiation on all these different implant surfaces have different effects at the microscopic level. Purpose. The purpose of this project is to expand on previous osteoblast attachment studies and investigate the osteoblast attachment, proliferation, and differentiation on five different types of implant surfaces: (1) Machined surface of surface roughness (Sa) of 0.3 – 0.4 µm; (2) Anodized yellow surface 0.3 – 0.5 µm; (3) anodized yellow surface 0.8 µm; (4) SLA surface of 1.6 µm; and (5) Biodenta surface treated (BST) surface of 1 µm. BST surface (Biodenta Swiss AG, Berneck, Switzerland) is anodized during the manufacturing process to have an amorphous titanium oxide layer. This process allows the BST surface to have its surface roughness enhanced via open porosity to promote osteoconduction. Materials and Method. Human fetal osteoblast stem cells were cultured for two weeks on the five different types of implant surfaces. Three genes were examined: Collagen Type 2 (COL1A2), Runt-related transcription factor 2 (RUNX2) and Osteocalcin (BGLAP) because of their role as genetic markers of osteoblast attachment, proliferation, and differentiation. The quality of the mRNA was checked with a spectrophotometer and cDNA was synthesized for quantitative RT-PCR. Genes were analyzed by means of melting curve analysis and relative quantitative Ct calculation to determine fold change. Results. The anodized 0.3 – 0.5 µm surface displayed up-regulation of COL1A2 (n-fold of +1.589) but down-regulation of RUNX2 and BGLAP (n-fold of -1.109 and -2.624, respectively). However, the anodized 0.8 µm surface presented opposite trends for all three genes. RUNX2 and BGLAP were both up-regulated (n-fold of +1.406 and +1.778, respectively) while, COL1A2 exhibited the greatest down-regulation trend with respect to all surfaces (n-fold of -4.801). The BST specimens were the only surface type to exhibit up-regulation for all three genes. Of the three genes, COL1A2 and RUNX2 displayed the greatest fold change for the BST surface (n-fold of +2.462 and +2.688, respectively). Conclusions. mRNA expression of RUNX2, COL1A2, and BGLAP in human fetal osteoblast stem cells, cultured on five different surfaces, indicated various expression profiles. The expression of COL1A2 and BGLAP, characteristics of a more mature osteogenic phenotype, were exhibited on the rougher surface implants. Following this trend, the BST surface expressed the most mature osteogenic phenotype in this study.
    • Efficacy of Different File Systems in Removing Gutta-Percha Cones Coated with Nanoparticles and Bioceramic Root Canal Sealer

      Barak, Yaakov; Martinho, Frederico C. (2019)
      INTRODUCTION: The purpose of this study is to compare the ability of the XP-3D (XP) Shaper (Brasseler USA, Savannah, GA), TRUShape 3D (TS) Conforming Files (Dentsply, Tulsa, OK), and Vortex Blue (VB, Dentsply) files to remove gutta-percha and BC Sealer (BCS, Brasseler USA, Savannah, GA) from root canals, and to compare the time necessary for retreatment. MATERIALS AND METHODS: 36 extracted single-rooted mandibular premolars were instrumented, and obturated with gutta-percha and BCS. The teeth were then retreated with either XP, TS, or VB. The teeth were sectioned and analyzed with a digital microscope at 35x and ImageJ software for the percentage of material on the canal walls. RESULTS: All groups removed obturation material to a similar extent. XP was significantly faster than TS or VB. CONCLUSION: There is no significant difference in the ability of XP, TS, or VB in removing obturation material, however, retreatment with XP is significantly faster.
    • The Relationship Between Short Term Healing of Periapical Lesions and Glycemic Control: A Pilot Study

      Zhou, Zuwu; Chand, Priya; Tordik, Patricia (2019)
      The aim of this study was to evaluate the relationship between HbA1c level and short-term healing of periapical lesions after non-surgical root canal treatment (NSRCT). After NSRCT, digital periapical radiographs were taken and blood samples were drawn for HbA1c analysis. To assess short-term healing (PAI difference), subjects returned after six months for a radiograph and blood draw. A calibration exercise established the reliability of the PAI scoring process. Thirty-eight subjects returned for the recall. The relationship between HbA1c level and also the co-variables, with healing was explained using Spearman’s rho and logistic regression. There was a significant correlation between healing and HbA1c level (rs = -.52, p ≤.0001), age (rs = -.44, p ≤.003), recall days (rs =.29, p ≤.036), and cardiovascular status (rs = -.34, p ≤.018). A final logistic regression showed a significant relationship between HbA1c level and short-term healing of periapical lesions (R = .62, p≤ .05).
    • Utilizing Charged Membrane Technology for Endotoxin Removal with Potential Use in Endodontic Procedures

      Yeung, Wing-Yee; Ernst, Robert K.; 0000-0002-3571-2484 (2019)
      AIM: To examine the application of a positively-charged polyvinylidene fluoride (PVDF) membrane for removing liquids and endotoxins. METHODOLOGY: Absorbency and endotoxin removal of paper points from various manufacturers was compared with PVDF membrane. The paper points and the PVDF membrane were evaluated for endotoxin binding using Limulus Amebocyte Lysate (LAL) assay. New paper points and the PVDF membrane were evaluated for the presence of endotoxins. RESULTS: Absorbency and endotoxin removal with the 0.22µm PVDF membrane was significantly greater than any of the paper points tested. There was significantly more endotoxin found in new paper points compared to the PVDF membrane. CONCLUSION: Our study showed that the 0.22μm PVDF membrane was significantly more absorbent and removed more endotoxins than paper points. Commercially available paper points were found to be contaminated with endotoxins and mechanical agitation of the PVDF membrane did not release endotoxin.
    • Evaluation of a Poly(Lactic-Co-Glycolic) Acid-Coated β-Tricalcium Phosphate Bone Substitute for Alveolar Ridge Preservation: Multicenter Randomized Control Trial

      West, Brandon M.; Saito, Hanae (2019)
      Purpose: The aim of this study was to determine whether the efficacy of PLGA-β-TCP in Alveolar Ridge Preservation (ARP) with histological analysis of the extraction socket following four months healing was similar to FDBA + CP as the control. Materials and Methods: 45 adult patients in this multicenter randomized controlled clinical trial were randomly assigned into treatment group A [PLGA-β-TCP] or group B [FDBA + CP] for ARP of a single extraction socket. Results: 45 bone core samples were harvested. Vital bone was present in intimate contact with the surface of β-TCP graft particles. Histologic measurements revealed no statistically significant difference between the test and control groups in percent vital bone after four months healing. Conclusion: This investigation demonstrated the similar efficacy of PLGA- β-TCP to FDBA as a bone substitute in ARP.
    • Effects of Glycemic Control on Soft Tissue Wound Healing around Dental Implants for Patients with Type 2 Diabetes

      Hurwitz, Morgan Barker; Oates, Thomas W. (2019)
      This study evaluated the effects of glycemic status on soft tissue wound healing following dental implant placement. A total of 164 edentulous patients with HbA1c levels up to 11.5% received two mandibular transmucosal dental implants. Patients’ self-reported pain (VAS and # days with pain) and soft tissue healing (edema, erythema, exudate, oral pain, flap closure, infection, and hematoma) were evaluated one week after placement. HbA1c and diabetes status were not significantly associated with any soft tissue healing complications. Pain_VAS was significantly correlated with Edema, Infection, Days in Pain and Oral Pain. Flap Closure was correlated with Oral Pain. Infection was correlated with Oral Pain and Days_Pain. Stepwise regression also identified HbA1c as significantly contributing to the VAS pain score. The findings of this study clarify the low risk for post-surgical healing complications independent of poor glycemic control, extending the opportunities for dental implant therapy for patients with diabetes.
    • Investigator/Faculty Onboarding: Facilitating the Transfer of Your New PI

      Hoffman, William; Sack, Karen; Simons, Janet (2019)
    • The Role of Nociceptors in Orthodontic Tooth Movement, Pain, and Alveolar Bone Remodeling

      Elnabawi, Omar; Pae, Eung-Kwon
      Objective: To determine the effects of selectively ablating transient receptor potential vanilloid 1 (TRPV1)-expressing nociceptors on orthodontic tooth movement, pain, and alveolar bone remodeling. Methods: Resiniferatoxin (RTX) or vehicle was stereotaxically injected into left trigeminal ganglia in adult C57BL/6 mice. After 1 week, orthodontic spring was placed between left maxillary first molar and upper incisors. Pain level was evaluated by measuring mouse grimace scale (MGS) and bite force before and after 1, 3, and 7 days following the procedures. After 12 days, micro-CT was used to quantify tooth movement and analyzing alveolar bone changes. Results: Experimental tooth movement increased MGS scores and decreased bite force. RTX ablation of TRPV1+ nociceptors attenuated MGS scores and relieved the reduction in bite force. The extent of tooth movement was decreased in RTX-treated group, but interradicular alveolar bone volume was not affected. Conclusion: Selective ablation of TRPV1+ nociceptors significantly decreases tooth movement and pain.
    • Elucidating the Role of Fatty Acid Synthase in Oral Carcinogenesis and Potential Therapeutics

      Wisniewski, David John; Schneider, Abraham; 0000-0002-7514-7918
      The 5-year overall survival rate in oral squamous cell carcinoma (OSCC) has remained relatively unchanged over decades, due to late stage diagnosis and high recurrence rates. This work investigates two potential contributing risk factors associated with OSCC development: nicotine, present in traditional combustible tobacco cigarettes and electronic nicotine delivery systems, and high glucose as associated with Type II diabetes and hyperglycemia. A novel therapeutic, TVB-3166, for OSCC treatment was also studied through in vitro experiments, which may help improve clinical treatments for fully developed, often late-stage OSCC. Through cell viability and growth assays, scratch assays to mimic in vitro migration, and western blotting, we determined that both nicotine and high glucose caused oral dysplastic keratinocytes to exhibit an increase in malignant-like behavior. High expression levels of fatty acid synthase (FASN), a key de novo lipogenic enzyme, have been implicated in OSCC, and this work presents the first evidence that both nicotine and high glucose markedly increase oral dysplastic keratinocyte FASN expression, which drives epidermal growth factor receptor (EGFR) signaling, a key pro-oncogenic signaling pathway commonly associated with oral carcinogenesis. We also demonstrate that TVB-3166, a novel selective FASN inhibitor, induces apoptosis and reduces in vitro OSCC cell migration. Moreover, TVB-3166 inhibits basal EGFR activity and several other oncogenic signaling proteins. This further establishes a potential role for FASN and EGFR not only in the progression of oral epithelial dysplastic pre-malignant lesions, but in fully-developed OSCC tumors. Overall, this work suggests that both nicotine and high glucose play a role in OSCC progression, specifically as it relates to FASN-dependent EGFR activation. Further, the novel drug TVB-3166 should be investigated in future pre-clinical animal models as a potential adjunct to OSCC therapeutics. Through an improved understanding of risk factors for OSCC development, as well as determination of novel therapeutic strategies, this work aims to improve overall patient survival through prevention of OSCC development, as well as discovery of new adjunctive treatments for fully established tumors.
    • Comparative Microbial Adherence to Various Implant Dental Restorative Materials

      Alshehri, Malek Rofidi A; Masri, Radi, 1975-
      The oral cavity contains the most complex microbial community of the body, which has more than 700 bacterial species. These microbial species colonize different habitats in the oral cavity. The biological interaction between dental restorative materials and the encompassing oral microbes is one of the most important factors for their clinical prognosis. Many studies have shown that there are distinctive interactions between the rate of microbial formation and the restoration material itself. Currently, there are several Implant Dental Restorative Materials on the market like poly-methyl methacrylate, feldspathic porcelain, dental zirconia, and dental composite resin. The purpose of this study was to comparatively evaluate initial adherence for C. albicans and S. aureus on five different implant dental restorative materials. Ten samples/group were constructed as 5mm x 5mm x 2.5 mm rectangles and were fabricated as per the manufacturer's instructions for each groups. Five groups were made from different types of materials: Polymethyl methacrylate denture material processed with the compression molding technique (PMMA), computer-aided design and computer-aided manufactured dental acrylic (CAD/CAM PMMA), feldspathic porcelain, dental zirconia, and pink dental composite resin. There was a significant difference between the five groups for C. Albicans (F=891.16, p=.0005). CFUs/ml for the pink dental composite resin were significantly higher than the other four groups. However, The dental zirconia group showed the lowest CFUs/ml for initial adherence between all the groups. For S. aureus, CFUs/ml for the pink dental composite resin was significantly higher than the other four groups. Heat polymerized PMMA and the CAD/CAM PMMA group showed significantly higher CFUs/ml than Feldspathic porcelain and dental zirconia groups. In conclusion, there was a significant difference between the five groups for initial adherence of C. albicans and S. aureus. The dental zirconia group showed the lowest initial adherence and the pink dental composite resin group showed the highest initial adherence for both microbes. Within limitation for this study, understanding what is the best for final dental restorative material from aspect of how much it could harbor microbes is an important factor in the final success of treatment and this study investigated this aspect under control conditions.