Now showing items 41-60 of 250

    • Metagenome and Metatranscriptome Analysis of the Subgingival Bacteria in Periodontal Disease. A Systematic Narrative Review

      Wohl, Hirschel; Aichelmann-Reidy, Mary Beth (2021)
      The main purpose of this systematic narrative review is to determine the difference in abundance of bacteria and bacterial genes of subgingival microflora of human periodontal pockets compared to healthy sites, via Metagenomic and Metatranscriptomic analyses. Databases EMBASE and MEDLINE were searched for articles, with earliest records from 1978. Main outcome measures included: 1) Bacterial genera and/or species significantly increased 2) Most prevalent or significantly upregulation of genes. Ten studies met selection criteria and were included in the study. Nine studies were cross-sectional, and one was longitudinal. Main results showed trends of specific bacteria and genes found in periodontal pockets. However, within the limitations of this narrative review, trends of abundant bacteria and genes does not imply these specific species or genes are actively participating in disease progression. Nine of ten included studies were cross-sectional in design with eight studies being metagenome based and not able to measure gene expression.
    • The Color Stability of 3D-Printed and Milled Zirconia Crowns

      Spatz, Harrison; Masri, Radi, 1975-; 0000-0002-3583-7674 (2021)
      Purpose: This is an in vitro study on the color stability of 3D-printed and milled zirconia crowns. Materials and Methods: A total of 18 samples were tested, 9 milled and 9 printed zirconia crowns. Change in color (ΔE) was assessed before and after samples were soaked in solutions of coffee, chlorhexidine and distilled water for a simulated period of 1 week. Two-way ANOVA was used to compare between the groups. Results: There was a significant difference (P = .003) between ΔE of samples soaked in chlorohexidine (4.24 ±3.62) versus coffee (8.84 ±7.48) and between ΔE of samples milled (1.64 ±1.12) versus printed (11.11 ±3.96, P ≤ .0001). Conclusion: Printed zirconia crowns are more susceptible to staining than milled crowns. Printed zirconia crowns appeared noticeably darker when soaked in coffee and lighter when soaked in distilled water and chlorohexidine.
    • Tongue Asymmetry and Muscle Shortening During Speech in Partial Glossectomy Patients and Controls

      Miller, Natalie; Stone, Maureen L. (2021)
      Tumors of the tongue are routinely removed by partial glossectomy surgery. This study examines the extent of anatomical asymmetries caused by the glossectomy surgery and its effects on the tongue’s resting position and motor symmetry. Magnetic resonance imaging (MRI) data of ten control subjects and ten glossectomy patients were obtained. 3D tongue volumes were extracted from high-resolution MRI data using Matlab. Using cine- and tagged-MRI data, shortening of the genioglossus, transverse, and verticalis muscles were calculated during a speech task involving /∫/ and /l/. Anatomical asymmetries were observed in the control subjects, although they were generally small and less than in glossectomy patients. Glossectomy patients aimed to distribute their tongue volume evenly in the oral cavity, irrespective of anatomical asymmetry, by posturing their tongue towards the resected side. Glossectomy patients shortened more muscles when executing the speech task. Muscle shortening asymmetry was observed in both control and patient groups.
    • Optimal Antero-Posterior Position of the Maxillary Central Incisors and its Relationship to the Forehead in Adult Asian Males

      Kocan, Jessica; Sanchez, Dina (2021)
      Objective: To determine an optimal antero-posterior (AP) position of the maxillary central incisors (CI) and its relationship to the forehead in Asian males. Methods: Smiling profile photographs of 60 Asian males were obtained and divided into three groups based on the judged AP position of CI (“just about right,” “too far forward,” “too far back”), as evaluated by orthodontists and laypersons. CI position and forehead inclination (FI) were measured relative to glabella vertical (GV). Statistical analysis tested for differences among groups, differences between orthodontists and laypersons, and the relationship between CI position and FI. Results: Optimal CI position was 0.86mm anterior to GV. There were statistical differences between orthodontists and laypersons in the study groups. CI position and FI showed moderate positive correlation. Conclusions: In Asian males, the AP position of the CI can be evaluated relative to the forehead, to plan for optimized CI position and maximized facial harmony.
    • Evaluating Oropharyngeal Airway Volume in Patients with Class II Dental Relationships with Extractions vs Non-Extraction Orthodontic Treatment

      Feizi, Ariana Gabriela; Schneider, Monica, D.D.S., M.S. (2021)
      Purpose: The purpose of this study is to support the position of the AAO by demonstrating that the oropharyngeal volume does not decrease as a result of premolar extractions and orthodontic treatment. Materials and Methods: Cone-beam CT’s were obtained for twenty-seven orthodontic patients before and after treatment. Nine patients were treated with four premolar extractions, and eighteen treated non-extraction. Total oropharyngeal airway volume and minimum area of constriction were measured using InVivo Anatomage Software. Results: The initial and final airway volumes of the non-extraction group were correlated (p = 0.61). The total airway volume in the non-extraction cases showed a significant increase (p = .037). Conclusion: There was no significant change in oropharyngeal volume in Class II patients that underwent orthodontic treatment with extractions, however; patients that were treated non-extraction had a significant increase in oropharyngeal volume. There was no significant change in area of minimum constriction in either group.
    • Tongue Muscle Shortening Differences in Glossectomy Versus Non-Glossectomy Patients

      Dao, Anh; Stone, Maureen L. (2021)
      In cancers that affect the tongue, the most common treatment is glossectomy, a procedure that can have substantial effects on a patient’s intelligibility. We are seeking to identify the effect of this resection on the use of four muscles – genioglossus, transversus, verticalis, and superior longitudinal, which comprise the bulk of the tongue. MRI data was used to study differences in tongue muscle shortening patterns during the speech task “a thing” between patients who have undergone glossectomies and controls who have not. Speech data was collected from 2D tagged-MRI movies and reconstructed into 3D volumes at 26 timeframes. Velocity fields and tissue points were extracted and shortening was calculated to study how the muscles were used by glossectomies vs. controls to protract and retract the tongue during /θ/. The results reveal differences in function between the two groups, and potential compensation strategies for glossectomy patients.
    • The Contribution of TRPV1 S801 Phosphorylation to Nociception and Inflammatory Pain in Vivo

      Joseph, John; Chung, Man-Kyo (2020)
      Transient receptor potential vanilloid subtype 1 (TRPV1) is a nonselective cation permeable channel activated by painful stimuli, such as capsaicin and noxious heat, and enriched in many primary afferent neurons of the pain pathway. During inflammation, chemical mediators activate protein kinases (such as PKC) that phosphorylate TRPV1 and thereby enhance its function, which results in nociceptor sensitization. And this can result in a lower threshold for pain. However, the causal relationships between TRPV1 phosphorylation and pathological pain remain unexplored. To directly investigate the roles of one specific TRPV1 phosphorylation event in vivo, we genetically altered a major PKC phosphorylation site, mouse TRPV1 S801, to alanine. The TRPV1 expression pattern in sensory neurons of S801A knock-in (KI) mice was comparable to that in wildtype (WT) controls. In sensory neurons from KI mice, following the activation of PKC, the usual increase of capsaicin-induced currents was substantially impaired. Thermal hyperalgesia induced by PMA or burn injury in KI was identical to WT. Thermal hyperalgesia was only marginally attenuated in KI mice duirng inflammation. In contrast, PMA-evoked nocifensive responses and hyperalgesia to capsaicin were significantly attenuated in the hindpaws of KI mice. Ongoing pain from inflamed masseter muscle was also reduced in KI mice, and the pain was further inhibited by the TRPV1 antagonist AMG9810. These results suggest that PKC-mediated phosphorylation of TRPV1 S801 contributes to inflammation-mediated sensitization of TRPV1 to ligand, but not heat, in vivo. Further, this suggests that interference with TRPV1 S801 phosphorylation might represent a potential way to reduce inflammatory pain in the clinic, yet spare basal sensitivity and produce fewer side effects than with a more general TRPV1 inhibition.
    • Programmed Death Ligand 1 in Oral Potentially Malignant Epithelium and Implications of Regulation by Interferon Gamma

      Elnaggar, Manar; Younis, Rania H. (2020)
      Programmed death ligand 1 (PD-L1) is an immune-checkpoint regulator. Expression of PD-L1 in a subset of head and neck squamous cell carcinoma (HNSCC) was linked to improved response to immunotherapy. Oral potentially malignant disorders (OPMDs) are characterized by increased risk for malignant transformation. We investigated the expression of PD-L1 in immune cells (ICs) and epithelial cells of OPMD, which is essential to prevent progression to malignancy. Immunohistochemistry analyses in HNSCC whole excision tissue sections (104 patients) indeed demonstrated predominant expression of PD-L1 in the epithelial margins (~86%). This directly correlated with PD-L1 expression in underlying ICs (P=0.0172) with a predominating lichenoid pattern of IC infiltrate. Immunoblotting analyses demonstrated the role of human recombinant IFN-γ in the upregulation of PD-L1 expression in the oral premalignant cell line (DOK) with implications of downstream activation of pS6. Our work suggests a role for IFN-γ/PD-L1 in the immune escape of OPMDs.
    • Dimensional Stability of CAD/CAM Patterns: A Longitudinal Study

      Byun, Shane S.; Masri, Radi, 1975- (2020)
      The goal of this study was to investigate the accuracy, over time, of computer-aided design and computer-aided manufactured (CAD/CAM) dental patterns in two different materials (resin and wax) using two different fabrication methods (subtractive and additive manufacturing). The intaglio surface of the patterns (n=48/time period) were evaluated at five predetermined time periods (zero minutes, 20 minutes, 24 hours, one week, and two weeks) relative to fabrication time. Intaglio surface scans of the generated samples were aligned with the Best Fit alignment to the design file (.stl) and compared with 3D Compare on Geomagic Control X to obtain the deviations as a root mean square (RMS). Trueness of the patterns were compared at all time points using three-way Analysis of Variance (ANOVA) (=.05). Accuracy of dental patterns deteriorated over time. When materials were considered, wax had better dimensional stability than resin. When fabrication method was considered, milled patterns had better dimensional stability than printed patterns. Time, material type, fabrication method, and all their interactions, showed a significant effect, however, the differences were very small (ranging from <1 m to 20 m). Thus, both resin and wax CAD/CAM patterns fabricated by additive and subtractive manufacturing can be used to produce dental restorations with acceptable accuracy.
    • A clinical evaluation of the ability of finishing files to supplement the removal of bacteria and endotoxin from primarily infected root canals (Part I- Initial evaluation)

      Kim, Eunice; Martinho, Frederico C. (2020)
      Aim: The aim of this study was to evaluate the ability of XP-endo Finisher (XPF) to supplement the removal of bacteria and endotoxin from primary infected root canals after instrumentation. Methodology: This randomized and blinded controlled trial included eight subjects. Instrumentation was performed using Vortex Blue or XP-endo Shaper, followed by supplemental instrumentation with XPF. All canals were irrigated with 2.5% sodium hypochlorite. Bacterial and endotoxin samples were taken using sterile paper points. Samples were collected before and after instrumentation and after XPF. Results: Bacteria was present in all root canals. After XPF, bacterial mean was reduced from 255 ± 311.82 CFU/mL to 2.5 ± 7.07 CFU/mL (p= .056). Endotoxin was detected in all root canals by the LAL method (KQCL test). After XPF, endotoxin mean was significantly reduced from .85 ± .26 EU/mL to .03 ± .01 EU/mL (p= .00004). Conclusion: The findings of this study showed that the supplemental use of the XP-endo Finisher after root canal instrumentation was effective in significantly reducing endotoxin but not bacteria present in primary endodontic infections.
    • Use of a Functional Chewing Gum in Reduction of Gingival Inflammation

      Merati, Arash; Shiau, Harlan (2020)
      Control of plaque biofilm is central to prevention of gingivitis. In addition to professional care, effective oral hygiene measures are known to improve gingival health. The objective of this study was to investigate the effect of chitosan/blackberry-extract, delivered in a chewing gum, as an adjunct to oral hygiene, on gingival inflammation and plaque biofilm accumulation. In this 12-week randomized controlled study, the use of chitosan/blackberry-extract gum was compared to placebo in 34 subjects (17/17). Plaque index(mPI) and gingival index(mGI) were the main outcome measures followed at baseline, week 2, 4, 8, and 12. Measured patient compliance and mPI had no significant difference between experimental and control at any interval during the study. mGI was significantly lower for the experimental group compared to control at 12 weeks(P<0.005). Chitosan/blackberry-extract chewing gum may be beneficial in reduction of clinical signs of gingival inflammation and has potential as an adjunct to routine oral hygiene.
    • The Accuracy and Efficiency of a Dynamic 3D Navigation System for Negotiating Calcified Canals

      dianat, omid; Chand, Priya (2020)
      The purpose of this study is to compare the use of a dynamic navigation system (DNS) to a freehand (FH) method for locating calcified canals. Sixty single-rooted teeth with obliterations were selected. In the DNS group, access preparation was made under navigation and in the FH group without any guidance. Linear and angular deviations and reduced dentin thickness were measured. Furthermore, efficiency was evaluated. The mean linear and angular measurements showed significantly less deviations in the DNS group compared to the FH group. Reduced dentin thickness, at both levels, was significantly less in the DNS group. Furthermore, DNS was faster and more successful than FH method. The DNS group showed only one unsuccessful attempt, compared to five perforations and three large transportations in the FH group. Within the limitation of this study, the dynamic navigation system allowed for more accurate and efficient negotiation of the calcified root canal system.
    • Tongue Position in Glossectomy Patients vs. Controls in /s/ during Speech with consideration for the effects of Palatal Features

      Rezaei Boroun, Atefeh; Stone, Maureen L. (2020)
      Purpose: This study examines the tongue behavior of glossectomy (N = 8) and control (N =12) speakers using a combination of high-resolution and cine- MRI. The speech task “a geese” phonetically spelled /əgis/, was used to measure anterior tongue displacement, termed “anteriority”, for the /ə/, a neutral vowel, and the /s/. Effects on anteriority due to palate height, arch perimeter, inter-canine width and /s/ type were measured on controls and patients. There are two variants of /s/ in English: apical and laminal. The apical /s/ elevates the tongue tip to contact the palate, create a narrow, grooved constriction, and focus the jet stream of air onto the incisors. The laminal /s/ uses the tongue blade, just behind the tip, to create the grooved constriction, and the tip is kept lower in the mouth.[1, 2]
    • Variation in Accessory Branches of the Mylohyoid Nerve in the Posterior Mandible: An Anatomic Study

      Ottey, Elizabeth Alston; Stone, Maureen L. (2020)
      Purpose: To examine the courses and branching patterns of the mylohyoid nerve in adult cadavers in order to determine if there are accessory branches, which insert on the posterior mandible. Materials and Methods: 25 cadavers preserved in 10% formalin were dissected in the gross anatomy dissection lab. The mylohyoid and any varying branches were dissected and preserved as far as possible. The dissected cadaver’s data sets were analyzed using Image J software. Results: 12 out 25 (48%) cadavers had at least one accessory branch present that attached to the posterior mandible. The accessory branch identified was located an average of 2.3 cm from the posterior mandible. Conclusion: Accessory branches of the mylohyoid exist in the posterior mandible. Our next step is testing the identified branches to confirm if they are nerve fibers.
    • Accuracy of Dynamic Virtual Articulation: Trueness and Precision

      Hsu, Michael; Masri, Radi, 1975- (2020)
      Purpose: To study the effects of altering condylar settings and pin openings on the trueness and precision of virtual articulators versus mechanical articulators. Materials and Methods: Maxillary and mandibular typodonts with fiducial markers were mounted on a mechanical Artex-CR articulator and the mandibular teeth were prepared to allow guidance solely by the posterior determinants of the articulator and the incisal table. The relationship of the mounted typodonts was preserved digitally by scanning using manufacturer transfer plate adaptors. On the mechanical articulator, pattern resin was allowed to set between the maxillary and mandibular occlusal surfaces (area #25-30) at the endpoints of dynamic movements at three different condylar inclinations (SCI): 10°, 30°, and 45°, n=12/inclination, or at three different incisal pin openings (2, 5, and 10 mm, n=12/opening). All other articulator settings were kept constant. Resin specimens attached to the typodonts were scanned within five minutes of setting, then removed and the articulated typodonts rescanned. FDPs #25-30 were designed on the virtual articulator using identical parameters to the mechanical articulator. Dynamic virtual movements were used to sculpt the design and a file of the design was saved. The files of both types of samples were aligned and overlaid. Interocclusal separation was measured in triplicate at the indentation created by the mesiolabioincisal point angle on the incisal edge of #8 and the mesiobucco-occlusal point angle of #3. Trueness and precision of both types of articulators were calculated and compared using one-way ANOVA, followed by the Tukey HSD test (α=.05). Results: There was no statistically significant difference at altered pin openings in either trueness (F<.202, p>.37) or precision (F<3.134, p>.09) for the majority of measurements. The only significant difference was in the precision between the two types of articulators at 5mm incisal opening, and only at the anterior measurement point (F=15.134, p=.0008). However, these differences were less than 100 μm. When the SCI was altered, there was no statistically significant difference (F< 3.624, p>.05) between the virtual and mechanical articulators in trueness for 5 of the 6 measurements obtained (F<3.624, p>.07) or for all of the precision measurements (F<3.529, p>.07). The one trueness measurement that was significantly different (F=9.237, p=.006 ) occurs at SCI of 10º, and it was less than 100 μm. Conclusions: Dynamic movements on the virtual articulator were shown to be as true and precise as to the mechanical articulator. When there were deviations, these deviations were less than 100 μm and thus, these deviations may not be clinically relevant.
    • The effect of delayed curing time of a self-etch primer on shear bond strength of the orthodontic bracket

      Lee, Hyun San; Schneider, Monica, D.D.S., M.S. (2020)
      This study investigated if a delay in curing time of a self-etching primer (SEP) affects the shear bond strength (SBS) of orthodontic brackets and the Adhesive Remnant Index (ARI) score. In 2-Step group, the conventional two-step technique was used for enamel conditioning. In groups Delay0, Delay1, and Delay5, a SEP was used with various delays in curing time (0, 1, and 5 minutes). Stainless steel brackets were bonded to the specimens using composite resin adhesive and were tested for SBS. Then ARI scores were measured under naked eye, 2.5x, and 10x magnifications. The results showed no significant difference in mean SBS and the ARI scores between the SEP technique and the two-step technique. The findings also implied a delay up to 5 minutes in SEP curing time do not affect the SBS and ARI scores. Finally, there was no difference in the ARI scores measured under three levels of magnification.
    • Comparison of Setting Expansion of White MTA and Endosequence Root Repair Material Putty Fast Set

      Ghiasi Afjeh, Seyedeh Pegah; Chand, Priya (2020)
      The purpose of root end filling material in endodontic surgery is to provide a seal to prevent the ingress and egress of bacterial toxins into the periapical area. One reason for the sealing ability of these materials is their expansion upon setting. The aim of this study was to compare the percent linear setting expansion of WMTA and ERRM putty fast set using a linear voltage displacement transducer (LVDT) under controlled temperature of 37° Celsius. Materials were prepared according to the manufacturer’s instructions and packed into the hollow hydrophilic porous tubing. Approximately 200 µL of HBSS was added to the porous tube in order to initiate the setting reaction. Expansion changes were measured until it appeared to have plateaued. ERRM putty showed a significantly greater mean percent expansion compared to the MTA (P≤0.005). MTA expanded an average of 0.109% (0.08%-0.20%) while ERRM putty expanded an average of 6.63% (2.93%-8.89%).
    • Metformin Induces Pro-angiogenic Responses in Dental Pulp Stem Cells: Potential Applications in Craniofacial Bone Regeneration

      Ge, Sheng; Schneider, Abraham (2020)
      The present study was conducted to determine whether metformin, a low-cost drug widely prescribed to control type 2 diabetes mellitus, stimulates production of angiogenic factors to potentially enhance vascularization of dental pulp stem cell (DPSC)-based craniofacial tissue engineered bone. Bone tissue engineering utilizing stem cells, growth factors and scaffolds offer an attractive alternative for regenerating large craniofacial osseous defects versus autologous bone grafts. Yet, successful stem cell-based bone regeneration highly depends on proper adaptation of cells to hypoxia and reestablishment of a functional microvasculature. Recent reports show that metformin induces DPSC’s osteogenic differentiation; however, it remains unknown whether metformin stimulates DPSC-derived, pro-angiogenic responses to support bone regeneration. We found that metformin induced a marked but variable increase in DPSC-derived angiogenic factors, including VEGF and angiogenin, which were further amplified by hypoxia. These results point to a novel, pro-angiogenic action of metformin to potentially enhance DPSC-based vascularized craniofacial skeletal regeneration.
    • Prevalence of Atypical Radiographic Findings in Bitewings of Class II Composite Restorations: Detection and Assessment of Radiolucent Areas

      Bazerbashi, Jood; Sampaio De Melo, Mary Anne (2020)
      This retrospective study aimed to describe the prevalence of radiographic abnormalities in bitewing radiographs of proximal class II composite restorations. Bitewing radiographs of proximal composite restorations of adult patients who underwent restorative care at predoctoral clinics at the University of Maryland School of Dentistry from August 2014 to July 2016 were identified. Atypical radiographic features were categorized by type of material and location. The information recorded for patients included age, sex, tooth, and restored surface. Out of the 669 examined restorations, 16.5% radiographs showed no atypical radiographic findings and 83.5% restorations had unusual radiographic signs. The types of atypical radiographic findings were distributed as 16.5% internal voids, 3% overhang, 7.8% interlayer lines, 12.6% secondary caries, 20.7% interfacial gaps and 23.1% had multiple atypical findings. There is high prevalence of atypical radiographic findings in class II composite restorations, particularly in the body of the composite, premolars, and disto-occlusal restorations.
    • Role of Lipopolysaccharide and RANKL in Osteoclastogenesis: Potential Inhibitory Effects of C-Phycocyanin on the Respective Molecular Pathways of Osteoclastogenesis

      Al Qranei, Mohammed; Chellaiah, Meenakshi A. (2020)
      Many skeletal diseases are characterized by excessive bone loss. Bone loss is mediated by osteoclasts, which are differentiated from cells of the monocyte/macrophage lineage upon stimulation of two indispensable factors, the RANKL and M-CSF. Lipopolysaccharide (LPS), a bacterial pathogenic factor, has also been shown to engage in osteoclastogenesis during inflammatory events actively. C-phycocyanin (C-PC) is a phycobiliprotein found in the blue-green algae that showed many therapeutic effects, including anti-arthritic and anti-inflammatory properties. However, the exact mechanism by which LPS regulates osteoclastogenesis and also the impact of C-PC on osteoclastogenesis needs further elucidations. We studied the osteoclast differentiation process in vitro using RAW 264.7 macrophage cell line. First, we showed that LPS induced osteoclastogenesis in RANKL-primed cells in vitro. LPS elicited osteoclastogenic mechanism by signaling through the TLR4 receptor, which is expressed in osteoclast precursors. Here we also found that TNF-α secreted by osteoclast precursors in response to TLR4 stimulation regulated the processes of osteoclastogenesis via TNF-R signaling. Second, we tested the inhibitory effect of C-PC on osteoclastogenesis. We showed here that C-PC strongly inhibited the early stage of osteoclast differentiation, thus significantly suppressing RANKL- and LPS- mediated osteoclastogenesis. Nonetheless, osteoblast differentiation and activity were not affected by C-PC. Reactive oxygen species (ROS) are generated during RANKL-mediated osteoclast differentiation. While studying the possible mechanisms of osteoclast differentiation, we found that C-PC a) attenuated RANKL-induced ROS; and b) interfered with RANKL-stimulated NF-κB signaling by preventing the degradation of cytosolic IκB-α; subsequently, these resulted in the loss of sequential activation of the osteoclastogenic downstream markers such as c-Fos and NFATc1. We propose that a unique mechanism of osteoclastogenesis is mediated by bacterial LPS that can be targeted during inflammatory-mediated bone loss. Also, C-PC could potentially be used as a therapeutic compound in osteolytic diseases caused by osteoclast activation without affecting osteoblast function.