Penn Dental Medicine

Established in 1878, Penn Dental Medicine is among the oldest university-affiliated dental schools in the nation. The school's mission is to transform global oral health and well-being through exceptional clinical care, innovation, education, and research.

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Now showing 1 - 10 of 824
  • Publication
    Evaluation of Peri-implant Health Status
    (2024) Kashiwagi, Kosuke
    Objective The aim of this study was to document cofactors associated with peri-implant disease progression. Material and methods The clinical charts and radiographs of patients who received dental implant at University of Pennsylvania or outside office were reviewed for maximum 13 years. Cofactors were divided two categories in this study. Patient related factors included age, active periodontitis patient, keratinized tissue around implant, smoking, diabetes, and more than 3 co morbidities. Implant related factors included diameter, length, one or two stage surgery, screw or cement retained restoration, and restoration types. Results This study involved 1004 implants from 308 patients (mean age 76.6 ± 10.9 years). Implant survival rate was 94.2%, with 5.8% failures. At the patient level, 87.7% had surviving implants, and 12.3% had at least one failure. Active periodontitis, smoking, and having more than three comorbidities were associated with peri-implant disease. Conclusion From this retrospective study, active periodontitis patient, smoking, and more than three co morbidities might cofactors associated with peri-implant disease progression.
  • Publication
    THE HARD AND SOFT TISSUE DIMENSIONAL CHANGES FOLLOWING EXTRACTION AND RIDGE PRESERVATION WITH DIFFERENT MEMBRANES – A PILOT STUDY
    (2024) AlAsaad, Noor
    Introduction: Following tooth extraction, bone resorption can be expected, especially on the buccal wall. An alveolar ridge preservation procedure (ARP) is commonly performed to maintain appropriate ridge volume for future implant placement. Various materials and methods can be utilized during ARP, however, there is no consensus on the membrane selection when the intact buccal plate is present after tooth extraction. The objective of this study is to investigate the dimension changes of the hard and soft tissue followed by alveolar ridge preservation with different membranes used.Materials and Methods: This prospective randomized clinical trial aims to enroll 50 subjects divided into 5 groups of 10. Each group underwent RP with mixing allograft and xenograft(1:1 ratio) and received 1 of 5 membranes: absorbable collagen dressing (ACD), non-resorbable d-polytetrafluoroethylene (d-PTFE), cross-linked collagen membrane (CLCM), non-crosslinked ECM membrane (N-CLCM), or dehydrated human de-epithelialized amnion-chorion membrane (DHDA-C). An intraoral scan was obtained before the extraction. Immediately following the extraction, a Cone Beam CT was taken to evaluate the extraction socket (Initial-CT). 4 months after ARP, a second CBCT(Post-CT) and an intraoral scan were obtained. Measurements were performed using implant planning software. Intraoral scan files were superimposed on Initial and Post-CT. A region of interest (ROI) guide was utilized to provide an accurate slice for measurement and a horizontal reference line at 1 mm interval from the bone crest. Following the ROI guide, horizontal measurements were taken at 0-9 mm level for hard tissue and 0-3 mm level for soft tissue. Results: A total of 35 patients were enrolled in the randomized clinical trial when the report was written. After removing insufficient data, only 29 patients’ data were included in bone measurement and 21 for soft tissue measurements. ANOVA test was used for analyzing the results. The results showed no statistically significant differences in dimensional changes in hard tissue (p=0.3) and soft tissue volume (p=0.7) among different kinds of membranes used in the intact defects. Conclusion: There were no significant differences in the dimensional changes of hard and soft tissue between the membrane groups, suggesting that the membranes are equally effective in intact sockets. The rationale of the material selection is mostly a clinician’s choice. A larger sample size is needed to confirm these findings.
  • Publication
    THE EFFECT OF ANTIRETROVIRAL THERAPY ON THE INTEGRATED STRESS RESPONSE IN THE CENTRAL NERVOUS SYSTEM: IN VIVO ASSESSMENT IN SIV-INFECTED RHESUS MACAQUES
    (2024) Razan Rashad AbedAlthaqafi
    Despite the benefits of antiretroviral therapy (ART), a large percentage of people with HIV (PWH) still suffer from some form of neurocognitive impairment. Studies have shown that high degree of oxidative stress and inflammation remain present in the central nervous system of PWH, which can activate the integrated stress response (ISR) pathway. We previously showed that the levels of several markers for ISR activation, such as phosphorylated eukaryotic initiation factor 2α (P-eIF2α), were elevated in neurons and astrocytes in the cortex in autopsy brain tissue of PWH. Phosphorylation of eIF2α is mediated by four kinases, which will result in ISR activation, as reported in several neurodegenerative disorders. In general, ISR is an adaptive pathway; however, chronic ISR activation may contribute to neuronal damage and neurocognitive impairment in PWH. Recently, several studies have reported that certain ART drugs contribute to the persistence of HIV-associated neurocognitive disorders and can induce the ISR. The aim of the present study was to assess ISR activation in neurons, astrocytes, and oligodendrocytes in brain tissue samples of SIV-infected rhesus macaques in a lentiviral model of HIV infection. Methods We examined necropsy brain tissue specimens of 11 rhesus macaques, including SIV-infected/ART-untreated macaques (n = 3), SIV-infected/ART-treated macaques (n = 4), and uninfected/untreated (n = 4) macaques, with the aim to determine if ART aggravated ISR activation in the CNS. Formalin-fixed/paraffin-embedded sections of cortical tissue were immunofluorescently stained using an antibody to p-eIF2α to assess ISR activation and antibodies against MAP2, GFAP, and ASPA to label neurons, astrocytes, and oligodendrocytes, respectively. Results By semiquantitative analysis of images of the stained specimens we found that p-eIF2α levels in neurons was significantly higher in the SIV-infected/ART-treated group than in the SIV-infected/ART-untreated group. However, we did not observe differences in p-eIF2α levels in astrocytes the gray matter and oligodendrocytes in the white matter among the three groups. Conclusion In our study, we observed a significant increase in ISR activation in neurons in the gray matter of the SIV-infected/ART-treated rhesus macaques compared to the SIV-infected/ART-untreated rhesus macaques, which we did not observe in astrocytes and oligodendrocytes.
  • Publication
    CBCT ANALYSIS OF MAXILLARY AND MANDIBULAR BUCCAL BONE THICKNESS AND HIEGHT AFTER CONVENTIANAL ORTHODONTIC TREATMENT RESULTING IN AN ALTERED ARCH FORM: A RETROSPECTIVE STUDY.
    (2024) Hobani, Nour
    INTRODUCTION: Arch development is a common occurrence in orthodontic treatment to expand dimensions of the dental arch form to accommodate proper alignment of teeth. Less attention has been spent in the literature on the changes within the posterior region and the limitation of movement that exists in this area. The purpose of this study was to assess the consequence of using preformed arch wires for posterior arch development has on the surrounding periodontium during routine orthodontic treatment. MATERIAL AND METHODS: A retrospective CBCT study of 49 adult patients orthodontically treated with fixed appliances resulting in a change of arch. The measurements of interest were made on each CBCT scan at pretreatment (T1) and post treatment (T2) for the maxillary and mandibular first premolars (U/L4), second premolars (U/L5), and mesiobuccal (U/LM6) and (U/LD6) distobuccal roots of first molars. The parameters were: (1) alveolar bone height (ABH), (2) alveolar bone thickness (ABT), (3) transverse width Palatal-Palatal (P-P) cusps, (4) root inclination, and (5) the presence and/or absence of dehiscences/fenestrations. RESULTS: The percentage of fenestrations and dehiscences in the maxilla at T1 was 50.8% and it increased by 11.3% at T2, while in the mandible at T1 it was 66.6% and it increased by 10.3% at T2. The transverse width change was significant post-treatment. Post-nonextraction orthodontic treatment where posterior dental arch forms were expanded, there is a higher tendency to: (1) increase ABH (bone loss), (2) thinning of ABT and (3) expansion was mostly achieved by tipping rather than bodily movement. CONCLUSIONS: The results indicate that the routine practice of orthodontic arch development results in significant alterations in the dimensions of the alveolar bone. On average, all posterior teeth experienced bone loss in both the vertical and horizontal dimensions following orthodontic treatment. It is therefore strongly recommended that prior to initiating treatment of adult patients requiring uprighting posterior teeth and/or dental expansion, adjunctive treatment modalities, including orthognathic surgery, skeletal expansion and periodontal bone augmentation, be considered to prevent such dimensional changes.
  • Publication
    Skeletal Class II Malocclusion: Growth Modification vs Non-Growth Modification- A CBCT Study
    (2024-06-25) Brianna Tucker, DDS, MHS
    Abstract Objectives: To compare the skeletal, dentoalveolar, and soft tissue changes in Class II patients treated with Herbst or Pendex appliances using 3D cone beam computed tomography (CBCT) imaging. Materials and Methods: In Aim 1 the sample population comprised 23 Herbst patients (12.07 ± 1.49, 12 M/11F) and 23 Pendex patients (11.76 ± 1.18, 10 M/13 F). For Aim 2, 48 Pendex patients (10.61 ± 1.70, 30F/18M) were included. In Aim 3, the sample population comprised 20 Herbst (11.91 ± 1.49; 11F and 9M) and 20 Pendex (11.76 ± 1.23; 10F and 10M). Lateral cephalograms were extracted from CBCTs taken at three time points: initial (T1), 6 months after appliance removal (T2, Herbst) or immediately after appliance removal (T2, Pendex) and final (T3) and tracings were completed at each time point. To compare the soft tissue changes, profile silhouette images were generated from T1 and T3 lateral cephalograms. A survey was distributed to examiners, including 9 orthodontic faculty (7M/2F), 11 postgraduate orthodontic residents 2M/9F), 11 predoctoral dental students (5M/6F), and 12 laypersons (6M/6F). After a normality test, treatment outcomes across the three time points were compared using either ANOVA with Scheffe's posthoc test or non-parametric Friedman tests with Dunn's test. The two treatment modalities were compared using a 2-tailed unpaired t-test or non-parametric Mann-Whitney test (p < 0.05). Results: Aim 1: Changes in mandibular size and sagittal position were similar in both groups while ANB, Wits and overjet decreased significantly more in the Herbst group. Aim 2: Significant maxillary molar distalization of over 4 mm was observed and there were no significant changes in the lower anterior facial height or vertical dimension. Aim 3: The perceived improvement in the soft tissue profile was more significant in the Herbst group compared to the Pendex group. Conclusions: Both Herbst and Pendex appliances were successful in treating Class II malocclusion. The Herbst appliance demonstrated an effective Class II correction through skeletal and dental effects, while the Pendex changes were mostly dental effects. The Herbst appliance has a greater improvement in the soft tissue profile. Therefore, the Herbst appliance should be considered for patients with moderate skeletal Class II discrepancies who can benefit from improvements in their soft tissue profile.
  • Publication
    Evaluating a Novel Python Computer Vision Methodology for Predicting Secondary Bone Augmentation Needs in Dental Implants Based on Guided Bone Regeneration Outcomes and Clinical Factors
    (2024-05-31) Lin, Yi Te; Lander, Bradley; Zang, Zirui; Mangharam, Rahul; Wang, Yu-Bo; Chang, Yu-Cheng
    This retrospective cohort study aimed to develop a novel prediction model for secondary bone augmentation (SBA) needs following guided bone regeneration (GBR) procedures in dental implant sites. The study utilized Python-based computer vision algorithms for cone-beam computed tomography (CBCT) analysis and compared their efficacy to conventional CBCT measurement methods. The study included 37 patients (76 implant sites) who underwent GBR procedures. CBCT scans were taken before GBR (T1) and prior to implant placement (T2). Clinical and demographic data were collected, including systemic health factors. CBCT analysis was performed using both conventional ridge width measurements and a novel Python-based computer vision approach that analyzed slice volumes. Risk indicators for SBA were identified using innovative variable selection techniques. The diagnostic efficacy of both CBCT analysis methods in predicting SBA needs was evaluated using Receiver Operating Characteristic (ROC) curves and Area Under the Curve (AUC) values. Results showed that the Python computer vision analysis (AUC = 0.876) demonstrated slightly superior predictive capability compared to conventional measurements (AUC = 0.847). Several clinical factors were identified as significant predictors of SBA needs, including diabetes mellitus, smoking history, and specific bone graft materials. This study demonstrates the potential of advanced computational approaches in improving the prediction of SBA needs following GBR procedures. The integration of detailed CBCT analysis with clinical factors provides a promising framework for personalized treatment planning in dental implantology. Future research with larger sample sizes and standardized GBR procedures is recommended to further validate and refine this predictive model.
  • Publication
    Comparison of Bone Remodeling in Midpalatal Suture during Maxillary Expansion between Young and Middle-Age Mice
    (2024-06-26) Contreras Salas, Mary Cruz
    Maxillary expansion is the most common procedure in orthodontics for correcting maxillary transverse deficiency. Despite its widespread use, standardized clinical protocols often neglect age-related differences in cellular responses, which may significantly impact treatment outcomes. To investigate these variations, we conducted comprehensive experiments on 6-week-old and 12-month-old mice, representing young and middle-aged groups, respectively. We employed 0.012-inch Australian orthodontic wire attached to the maxillary first and second molars on both sides, delivering a force of 25g. The outcomes were monitored at key intervals post-intervention (days 0, 3, 7, and 14; n = 8 per group) to capture the dynamic changes in bone remodeling over time. Our evaluation methods included MicroCT analysis, tartrate-resistant acid phosphatase (TRAP) stain, immunofluorescence stain using antibodies to RUNX2, osteocalcin, Gli1, and Ki67, and TUNEL assay to assess midpalatal suture gap, osteoclastogenesis, osteogenesis, and mesenchymal stem cell (MSC) proliferation/apoptosis. Both 6-week- and 12-month-old mice exhibited successful midpalatal suture opening, but young mice demonstrated earlier and more intense osteoclast activity, along with higher expression of RUNX2 and osteocalcin. Young mice also exhibited a higher percentage of Gli1+Ki67+immunopositive cells, while middle-aged mice showed a higher percentage of Gli1/TUNEL-positive cells on day 3 after maxillary expansion. Our findings suggest that aging negatively impacts mechanical force-induced bone remodeling by reducing osteoclastogenesis, osteogenesis, and MSC proliferation while increasing MSC apoptosis.
  • Publication
    Molecular and functional heterogeneity and identification of fibroblasts
    (2024-06-28) Ko, Annette; Sahingur, Sinem Esra; Chang, Yu-Cheng; Ko, Kang I; Korostoff, Johnathan M; Chang, Yu-Cheng
    Introduction: Oral wounds heal with exceptional regenerative capacity, which contrasts skin wound repair. Paired related homeobox 1 (Prrx1) is a marker for mesenchymal progenitors in bone, and recent studies have demonstrated presence and functional significance of Prrx1+ fibroblasts in dermis. Our previous findings suggest pro-healing role of Prrx1+ oral fibroblasts in mouse model, thus we sought to examine equivalent Prrx1+ cells using human gingival tissue biopsies. Here, we hypothesize that human Prrx1+ fibroblasts reside in different oral gingival tissues and that they exhibit enhanced regenerative potential for wound healing. Methods: Human gingival samples were collected from the anterior rugae, healed sites (distal wedge, edentulous crest), and tooth-associated sites (marginal gingiva from crown lengthening procedure or osseous surgery) in accordance to approved IRB protocol. The tissues were processed in paraffin-embedded block and sectioned at 5um. Immunofluorescence staining was performed with antibodies against Prrx1 and vimentin to detect Prrx1+ oral fibroblasts in various oral anatomic sites. Image analysis was carried out by counting spindle-shaped vimentin+ and Prrx1+ cells in lamina propria, normalized by area (mm2). To examine the regenerative potential of Prrx1+ cells in oral tissues, human anterior rugae samples were collected and processed for single-cell RNA sequencing (scRNA-seq). Transcriptomic analysis was performed after combining with the public scRNA-seq data (GEO: GSE164241, GSE152042). Results: Prrx1+ fibroblasts were present throughout all types of oral soft tissues. Anterior palate tissue had 72% fibroblasts expressing Prrx1, which was significantly more than those found in distal wedge, crestal tissue and marginal gingivae (39%, 30%, 26%, respectively; P<0.05) in the reticular layer of lamina propria and submucosa. ScRNA-seq analysis of the combined data demonstrated upregulation of several WNT-associated genes in Prx1+ fibroblasts, such as SFRP1 and SLPI, which had previously been reported to be involved in stem cell function and regeneration. The transcriptomic analysis further revealed that Prx1+ fibroblasts exhibit progenitor phenotype with projected differentiation trajectory toward chemotactic fibroblasts and expedited wound healing potential via immunomodulation in innate immune response. Further characterization of these inflammatory fibroblasts showed high expression of intercellular adhesion molecule-1 (ICAM-1), suggesting its potential usage as a surface marker for identification. Conclusion: Our results demonstrate that human Prrx1+ oral fibroblasts reside in the deep layer of the lamina propria, particularly in the anterior palate at higher frequency compared to other anatomic sites. These fibroblasts may exhibit improved regenerative potential via modulating WNT-associated pathway and rapid resolution of inflammation. The findings provide new insight into the enhanced healing potential of oral fibroblast subpopulations that may contribute to developing surgical techniques targeted to improve unpredictable soft tissue augmentation.
  • Publication
    DUCTILE GRINDING OF DENTAL CERAMICS
    (2024-06-04) Bawazir, Marwa
    Objectives: The current brittle-regime grinding applied during the CAD/CAM milling and handpiece grinding is detrimental to the strength of ceramics due to the formation of microfractures. This work presents a safer yet efficient alternative known as ‘ductile-regime grinding’. The hypothesis is that dental ceramics will transition from brittle- to ductile-regime grinding, and applying ductile-regime grinding parameters, namely, threshold load and grit size, will significantly diminish strength loss while maintaining removal efficiency. Material and Methods: Disc-shaped samples of a lithium disilicate glass-ceramic (IPS e.max CAD), Feldspathic ceramic (Mark II), polycrystalline zirconia with different yttria concentrations (3Y-TZP and 5Y-PSZ) were tested. Micro-scratch tests with a single diamond indenter were conducted under controlled scratching loads. Additionally, grinding using conventional lapping technology was performed by controlling grinding grit sizes. The strength of scratched and ground samples under each tested condition was measured using a flexural strength test. Surface and subsurface damage were analyzed using Scanning electron microscopy (SEM) and Focused Ion Beam (FIB-SEM). The removal rate and surface roughness of ground samples were also measured. Statistical analysis was performed using one-way and two-way ANOVA. Results with p < 0.05 were considered significant. Results: SEM surface analysis of scratch tracks on tested ceramics revealed ductile and brittle removal modes under single-particle sliding. Strength degradation and subsurface damage observations validated the threshold loads and grit size of ductile grinding for IPS e.max CAD, Mark II, and 5Y-PSZ. Scratching and grinding at the subthreshold region preserved the strength of tested ceramics. 3Y-TZP showed high tolerance to damage with no drop in strength compared to the other three ceramics. Ductile grinding resulted in a comparable removal rate, less surface roughness, and maintained strength compared to brittle grinding. Conclusions: Establishing the threshold load and grit size for ductile grinding lays the groundwork for future research on implementing ductile-regime grinding protocols to achieve damage-free ceramics restorations.
  • Publication
    MECHANOSENSITIVE PIEZO ION CHANNELS IN RETINAL GANGLION CELLS
    (2024-05) Sripinun, Puttipong
    Piezo ion channels are a family of bona fide mechanically activated ion channels that play a crucial role in various biological processes by converting mechanical stimuli into electrical and chemical signals within cells. Discovered relatively recently, the family consists of Piezo1 and Piezo2, which are widely expressed across different tissues and cell types in vertebrates. Despite their broad expression, less is known regarding their roles and mechanisms in the visual system. This gap in knowledge presents a significant opportunity for research, particularly in understanding how these channels influence ocular functions and contribute to eye health and disease. We sought to interrogate the hypothesis that retinal ganglion cells (RGCs) express Piezo ion channels, enabling them to respond directly to mechanical strain, a critical factor in understanding their role in neurodegenerative diseases such as glaucoma. The research was structured around three specific aims designed to uncover the extent and implications of Piezo channel functionality in RGCs. The first aim focused on establishing whether Piezo ion channels are indeed expressed in RGCs, utilizing techniques such as semi-quantitative PCR and immunohistochemistry to detect the presence and quantify the levels of Piezo1 and potentially Piezo2 proteins and mRNA in the retina. This set the molecular groundwork for understanding mechanosensitivity in RGCs. The second aim validated the functionality of Piezo1 ion channel within RGCs using a pharmacological approach using a specific agonist of Piezo1 to monitor changes in RGC activity through calcium imaging and multi-electrode array recordings, assessing ion flux and changes in RGC firing in response to Piezo1 activation. This phase also explored whether the activation of Piezo1 which represents mechanical strains, highlighting the adaptive nature of RGCs to mechanical stress. The final aim was to develop and characterize a novel in vivo transgenic reporter mouse model, providing a tool for prolonged studies on how altered mechanosensitivity affects disease progression and recovery in RGCs. Together, these investigations provide significant insights into the mechanistic roles of Piezo channels in RGC biology and present potential new avenues for therapeutic intervention in ocular diseases marked by mechanical stress.