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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  • 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.
  • The Dental School Library

    Unknown author (1935)
  • Accelerated Orthodontic Tooth Movement in Adult Patients by Subsequent Micro-osteoperforations of Maxillary Cortical Bone

    Laraway, Robert Dane; Schneider, Monica, D.D.S., M.S.; 0000-0001-6539-7123 (2018)
    Objective: Determine if orthodontic tooth movement during space closure is accelerated after subsequent micro-osteoperforations (MOPs). Methods: Five adults requiring maxillary 1st premolar extractions participated. MOPs were performed unilaterally in the extraction site at the beginning of the study and four weeks later. Canines were retracted bilaterally and space closure was measured after two months. Results: Overall, the canine retraction rate was 0.34mm greater on the MOP side compared to the control side but showed statistically insignificant differences. When compared to our initial study, which only had one MOP application, canine retraction was 0.24mm greater but, again, was statistically insignificant. Conclusion: The results of this study show that the experimental side had greater retraction of than the control side. However, the difference was not statistically significant. More studies are needed to study the extent and duration of effects of MOPs on tooth movement in humans.
  • Development and Implementation of an Audiovisual Informed Consent Delivery System for Non-surgical Root Canal Therapy

    Aguilar, Lauren; Macek, Mark D. (2018)
    The aims of this mixed-methods study were (1) to explore patients' preferences towards informed consent for endodontic procedures, (2) to use focus group feedback to develop short audiovisual presentations, and (3) to determine whether the audiovisual format lead to a different level of understanding than traditional consent. First was a focus group to assess patient expectations and attitudes towards consent for non-surgical root canal therapy (NSRCT). Second was developing two short audiovisual presentations. Finally a clinical trial tested the videos with 50 patients at the University of Maryland School of Dentistry. A questionnaire was used to assess patient preferences, comprehension, and recall of the consent and analyzed. There were no significant differences between groups in terms of recall, comprehension, understanding, or attitudes. Nonetheless, the data collected may be useful to restructure informed consent procedures for NSRCT and set a precedent for innovative consenting procedures.
  • Development of a New Generation of Dental Rechargeable Nanocomposites with Anti-caries Properties

    Al Dulaijan, Yousif Ali; Xu, Huakun H. (2018)
    Dental composites are popular for tooth cavity restorations due to their aesthetics, conservative approach, and direct-filling abilities. However, composite restorations have limited lifetime due to several limitations, including secondary caries, fracture, minimal abrasion and wear resistance and higher marginal leakage. Indeed, secondary caries is the primary reason for composite restoration failure. Besides, several studies have shown that conventional dental composites accumulate more biofilms/plaque when compared to other restorative materials. Therefore, this dissertation aims to develop a new generation of dental composites with antibacterial effects, protein-repellent activities, and remineralization properties. Recently, a rechargeable composite was developed, but this composite has no antibacterial or protein-repellent activities. In this dissertation projects, the nanoparticles of amorphous calcium and phosphate (NACP) as remineralizing agent, dimethylaminohexadecyl methacrylate (DMAHDM) as an antibacterial monomer, and 2- metha-cryloyloxyethyl phosphorylcholine (MPC) as a protein-repellent agent were incorporated into the rechargeable composite for the first time. Mechanical properties of the new nanocomposites were evaluated. The characterization of protein adsorption was measured. A human saliva microcosm biofilm model was used to determine biofilm metabolic activity, lactic acid, and colony-forming units (CFU). Calcium (Ca) and Phosphate (P) initial ion release, recharge and re-release were investigated. All rechargeable nanocomposites have good mechanical properties that were compared to those of a commercial composite. The rechargeable nanocomposites containing MPC showed the ability to reduce protein adsorption, as well as the biofilm metabolic activity, lactic acid, and CFU. The rechargeable nanocomposites containing DMAHDM showed strong antibacterial properties through the great inhibition of biofilm metabolic activity and lactic acid, and CFU. The incorporation of bioactive agents did not compromise the Ca and P initial ion release and rechargeability. The release was maintained at the same level with increasing number of recharge cycles, indicating long-term ion release. Therefore, this new generation of rechargeable nanocomposites with long-term Ca and P ion release, antibacterial and protein-repellent activities will provide the needed therapeutic effects to remineralize and strengthen the tooth structures, prolong the restoration longevity, and inhibit secondary caries.
  • Implications of underperforming light energy delivery for posterior composite: insights into delivered radiant exposure, degradation characteristics, and biofilm formation.

    Maktabi, Haifa; Melo, Mary Anne (2018)
    Poor curing of composites due to incorrect position of a curing unit may trigger a negative pathway of events related to the bacterial growth-stimulating effect of released methacrylate monomers. An increased bacterial adhesion and biofilm formation as a result of incomplete polymerization may contribute to premature failure of posterior composite via secondary caries formation. The objectives of each chapter are: 1) to review the literature concerning the light curing process and implications for failures on posterior composites (chapter 1), 2) to investigate in vitro how the variations on light curing tip placement and irradiance exposure can impact the degree of conversion of conventional 2mm-increment composite and S. mutans biofilm formation (chapter 2). In summary, this set of studies support the importance of proper light curing for an acceptable clinical performance of posterior composites.
  • Bacterial Adhesion to Various Implant Surfaces

    Khatra, Navpreet Kaur; Masri, Radi, 1975- (2018)
    Dental implants provide a major course of treatment for patients who are partially or completely edentulous. These implants are biocompatible metal anchors that are surgically positioned in the jawbone to support the prostheses where natural teeth are missing. However, the use of dental implants has some disadvantages, which can result in complications. Once the clean implant surface is exposed in the oral cavity, it is immediately coated with salivary pellicle and subsequently colonized by oral microbial species. In fact, microbial adhesion and accumulation on implants are considered to play major roles in the pathogenesis of peri-implant mucositis and peri-implantitis. The physico- chemical characteristics of specific material surface are known to significantly influence the bacterial adhesion process. Therefore, the surface characteristics of dental implants have been refined and restructured over a period of time to improve the interaction of implants with host cells and tissues. Hence, investigating the microbiological aspects related to implant surfaces will provide important insights relevant to expectations of treatment outcome. To that end, in this study, we aimed to comparatively evaluate microbial adherence and accumulation on five different types of implants. Specimens were provided by Dental Implant Systems, Biodenta Group and implant surfaces included: .3- .5 μm anodized surface, 1 μm BST surface, .8- 1.0 μm anodized surface, 1.6μm SLA surface and .3- .4 μm machined surface. To assess microbial adherence, the cariogenic bacterial species Streptococcus mutans and the bacterial pathogen Staphylococcus aureus were studied. Results from these studies were analyzed using analysis of variance (ANOVA) and significant differences were further analyzed by Tukey’s Honestly Significant Difference (HSD) test. Pearson’s r was also used to evaluate the association between surface roughness and bacterial accumulation. The present study has demonstrated that not only surface roughness but other physicochemical properties such as surface charge, energy, wettability and biological factors such as host immune response and oral hygiene influence bacterial adhesion and accumulation around implant surfaces.
  • Can treating oral inflammation lead to the reduction in a systemic outcome? A systematic review looking into pregnancy and diabetes.

    Guy, Veronica; Oates, Thomas W. (2018)
    The contribution of periodontal disease to the development of adverse systemic consequences remains controversial. It is hypothesized that inconsistencies between studies is due in part to limitations in study design. This review assessed systemic conditions including adverse pregnancy outcomes and glycemic control for patients with diabetes in a combined manner based on a shared inflammatory mechanism of consequence. It is thought that the systemic consequences of periodontal inflammation can directly influence these systemic conditions. Therefore, this systematic review aimed to evaluate the consideration of the patients' medical management during the study and also the number of study participants as two important factors influencing the study outcomes. An article search was performed using OVID Medline, Cochrane library and EMBASE and a manual search was performed through November 2017. Randomized controlled trials published between 2000 and 2017 looking into the effectiveness of periodontal therapy on the rate of pre-term birth in a pregnant population and on glycated hemoglobin A1c in a type 2 diabetics were included. Primary outcomes were changes in HbA1c and differences in frequency of occurrence of pre-term birth. Medical management of the systemic condition under study was categorized from 0-3, based on stringency of study design and consideration for medical management during study participation. Risk of bias regarding randomization, allocation of sequence concealment, blinding, incomplete outcome data, selective outcome reporting and other biases were averaged using a cumulative assessment of factors considered in prior systematic reviews with shared studies. After article selection, randomized controlled trials including 17 on diabetes and 13 on pregnancy were combined for evaluation. Both increased sample size (R2=0.09, R value = 0.3) and improved stringency of medical management (Figures 13 & 14) were associated with diminished effects of periodontal therapy on systemic outcomes. Interestingly, risk of bias as assessed in previous systematic reviews showed a modest correlation (R2=0.104, R value= 0.32) with primary outcomes. This systematic review demonstrates that the disparate results in studies of periodontal therapy affecting systemic outcomes may be explained in part by study design, specifically stringency in consideration of medical management and sample size. The potential for confounding factors influencing outcomes remains a concern.
  • Parental Perception toward Dental Sedation in Pediatric Patients at the University of Maryland

    Almarwan, Marwah; Dhar, Vineet; 0000-0001-9351-9722 (2018)
    Purpose: To evaluate pre-operative parental perceptions towards sedation, through their knowledge, beliefs and attitude. The parents were also surveyed for post-operative satisfaction and acceptance of the sedation procedure within 2 days of the dental treatment under sedation. Methods: One hundred and one parents of children underwent dental treatment under sedation at University of Maryland responded to two questionnaires: pre-operative and post-operative (24-48 hours). Results: Most of the parents were the only one accompanying person with the child undergoing dental sedation (57.43%). Fisher's exact test was significant (0.006) in parents who thought that dental sedation was of a low risk and had education of college or more. Conclusion: Less than half of parents brought an additional responsible person with them to the child's dental sedation appointment, suggestive of inconsistent compliance with the pre-operative instructions. Parents with higher education (postgraduate) viewed dental sedation for children as a safe approach.

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