School of Dentistry: Recent submissions
Now showing items 1-20 of 658
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MDental 2023University of Maryland, Baltimore. School of Dentistry, 2023
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The quality of information on oral hygiene instructions for orthodontic patients in TikTok videosObjective: The study aimed to assess the reliability, content, quality, and overall usefulness of orthodontic oral hygiene instructions in TikTok videos. Methods: The final videos were evaluated for content, reliability, quality, and usefulness by using a content domain checklist, DISCERN questionnaire, and Global Quality Scale (GQS). Descriptive video characteristics were also recorded. Results: Dental professionals uploaded 70.00% of the TikTok videos, with orthodontists responsible for 39%. The videos had average scores of 2.19 for DISCERN, 3.96 for content, 2.14 for GQS, and 6.10 for usefulness. Video length was significantly associated with content scores (r = 0.3553, P = 0.0003), usefulness (r=0.3553, P = 0.0003), and quality (GQS) (r=0.2620, P=0.0085). Conclusion: Most TikTok videos on orthodontic oral hygiene were uploaded by dental professionals. Reliability, content, and quality of the videos were all poor. Videos were considered slightly useful. Longer videos were significantly correlated with higher content, higher quality, and increased usefulness.
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Perception of lip attractiveness: a survey of orthodontists, general dentists, and laypersonsWe aim to investigate the proposed standards of ideal lip proportions and compare those standards to what different people view as most attractive. A 16-question survey was distributed via Qualtrics to orthodontists, general dentists, and laypersons asking demographics as well as opinion-based questions regarding a series of facial photographs. Photographs were digitally altered using Adobe Photoshop to produce different dimensions of the lips from both profile and frontal views. Participants were asked to rate the perceived attractiveness of the lips shown. Regardless of occupation, individuals preferred the appearance of slightly protrusive or thicker lips. Retrusive and thin lip varieties had the lowest median attractiveness scores. Average values for lip projection and thickness were not found to be mutually agreed upon across occupation types (p<0.05) and average lip thickness was not mutually agreed upon between age groups of orthodontists (p=0.004). Based on the results of this study, care should be taken not to produce retrusive or thin lips during orthodontic treatment. Acceptance of a slightly thick or protrusive lip profile may be a more esthetic or well-accepted patient outcome.
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Three-Dimensional Assessment of Virtual Clear Aligner Attachment Removal: A Prospective Clinical StudyVirtual attachment removal (VAR) is a process used in digital dentistry to prefabricate retainers by removing attachments from a digital scan before the removal of clear aligner attachments. This study aims to evaluate the accuracy of VAR in the maxillary arch. 110 teeth were analyzed from a sample of 54 maxillary scans from 25 subjects. Models with attachments were virtually debonded using Meshmixer® and superimposed over the control group in MeshLab. Vector Analysis Module was used to calculate 3D distances on the buccal surfaces between the superimposed models. The VAR protocol showed no statistical differences in the root mean square between different tooth segments with an overall tendency for inadequate attachment removal. No difference between the groups were found when regarding the number of attachments was used as a main factor. The VAR technique is precise enough for the fabrication of retainers from printed dental models in a clinical setting.
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Effect of Polydopamine-RGD Peptide Coating on the Adhesion of Cultured Fibroblasts on Polymethylmethacrylate Provisional Custom Abutment MaterialsCellular attachment properties of the temporary and prosthetic abutment is one of the important factors for creating optimal peri-implant soft tissue around the implant. Surface modifications appear to play an important role in promoting early healing of the soft tissue around the dental implant, affecting primarily the epithelium, fibroblast, and osteoblast cell behavior. Another strategy to better manage peri-implant and abutment soft tissue integration is to coat the surface with bioactive agents to enhance biocompatibility. Among the most commonly utilized are proteins and peptides. The proposed in-vitro study will provide better insights of surface characteristics for implant-abutment interface by application of the peptide RGD for optimized attachment of peri-implant soft tissue cells. The hypothesis is that application of polydopamine and the peptide RGD on the implant-abutment surface can improve fibroblast early attachment, migration and proliferation, thereby advancing early wound healing and establishing peri-implant soft tissue attachment.
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The Etiology of Peri-implantitis: Microbiological Profile Within and Around Dental Implants and the Associated Human Immune ResponseObjectives: To characterize the microbiome composition within and around dental implants of peri-implantitis subjects and within and around healthy implants using 16S rRNA gene sequencing, and to profile salivary inflammatory mediators associated with peri-implantitis compared to healthy controls from the same subjects. Methods: A total of 24 subjects (peri-implantitis n=14, healthy n=10) were enrolled in the study. From the 24 subjects, 24 endosseous implants from affected (peri-implantitis) and 14 healthy controls were included in this cross-sectional study. Samples for microbiological analysis were obtained from the internal surfaces of dental implants and peri-implant sulcus using sterile paper points. DNA was extracted and 16S rRNA gene was amplified using universal primers targeting the V3-V4 regions. Amplicons were sequenced using Illumina MiSeq platform. Alpha and beta diversity, core microbiome, and taxa differential abundance were assessed. Saliva was collected from the same subjects for immunology-based assays. Salivary inflammatory mediators in peri-implantitis and healthy implant subjects were profiled using antibody arrays. Results: A significant increase in microbial diversity was observed in the internal implant surface of healthy implants compared with the internal surfaces of peri-implantitis (Shannon P= 0.02), and no significant differences in microbial diversity between healthy implants sulci and peri-implantitis pockets (Shannon P= 0.82). Bacterial community structure was significantly different within implant in both healthy and peri-implantitis groups (P= 0.012) but not significantly different around implants in both healthy and peri-implantitis (P= 0.18). Enterococci is the predominant bacteria within peri-implantitis (LD >2.0, P< 0.05). Abundant species in peri-implantitis were C. leadbetteri, T. maltophilum, Peptostreptococcus, Neisseria, P. gingivalis, and P. endodontali, L. lactis and F. alocis (P < 0.05). Gram-positive bacteria such as S. salivaris, P. melaninogenica, L. wadei, and Actinomyces spp were more abundant in the peri-implant healthy sulcus. Around 48% of detected bacteria were cultivable in general media. In addition, out of 105 analytes examined in saliva, we found that 29 mediators were upregulated in subjects with peri-implantitis (P < 0.001). Conclusions: Our results indicate that microbial colonization of the internal implant surface may act as a major contributor to the etiology of peri-implant disease. Multiple inflammatory mediators were significantly elevated in the saliva of peri-implantitis patients compared to healthy implant patients.
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Effect of Contact Type on Caries Experience in Primary DentitionPurpose: The aim is to evaluate effect of contact type and other caries risk factors (diet, plaque, and fluoride) on caries experience in primary dentation. Secondly, to assess prevalence of OXIS contacts among 3-10 years old children enrolled in the study. Methods: Clinical examination was completed on healthy children 3 to 10 years of age. Contact type of primary molars was recorded based on OXIS classification. Information on other caries risk factors were collected (plaque, fluoride, and diet habits). The outcomes assessed included clinical caries (presence/absence), decayed, missing, and filled primary teeth (dmft), decayed teeth (dt), and decayed surfaces (ds). Results: A total of 277 contacts were examined in 107 children ( 51 females and 56 males). Moderate plaque was found to be associated with dmft and dt for contacts S, I, and X. High diet frequency was associated with high dmft and dt scores for contacts S, I, and X. Contact type I showed significant association with dmft compared to other contacts in multivariable analysis. Conclusion: Both high diet frequency and moderate plaque index were linked to higher caries experience in children with contact types S,I, and X. Contact type I found to be associated with higher dmft scores compared to other contacts (X and S).
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Comparison of Shear-bond Strength of Orthodontic Brackets on Enamel with use of Pro Seal with Assure PlusTitle of Thesis: Comparison of Shear-bond Strength of Orthodontic Brackets on Enamel with use of Pro Seal with Assure Plus David Greene, Master of Biomedical Sciences, 2023 Thesis directed by: Dr. Dina Sanchez, Director of Predoctoral Orthodontics, Clinical Assistant Professor, Department of Orthodontics and Pediatric Dentistry We aim to investigate the shear bond strength of orthodontic brackets bonded with Assure Plus alone and in combination with Pro Seal, following the manufacturer's recommended bonding protocol. Forty-two (42) extracted premolar human teeth were randomly assigned to two bonding groups, the control group (Assure Plus) and the test group (Assure Plus and Pro Seal). After bonding, the teeth were stored at 37°C for 24 hours. Next, the shear bond strength test was completed. The results of the Mann- Whitney test showed there was not a statistical difference of shear bond strength between the two groups for the variables, Peak Load and Shear Bond Strength. The use of Pro Seal with Assure Plus as a preventive measure for white spot lesions during orthodontic treatment does not negatively impact the shear bond strength of orthodontic brackets during treatment.
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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.
