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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Publication OPTIMIZING SPEED SINTERING PARAMETERS FOR YTTRIA-STABILIZED ZIRCONIA(2024-12-19) Alshahrani, AbdulazizSintering zirconia-based ceramics is a time-consuming process that uses slow heating and cooling rates. To fulfill the requirement of chair-side production of zirconia, speed and high-speed sintering technologies have emerged. However, the impact of these recent technologies on the thermal (transient stresses), physical, optical, and mechanical properties of yttria-stabilized zirconia (YSZ) still needs to be investigated. Therefore, a total of 750 disc-shaped specimens were pressed from zirconia powder (Zpex series, Tosoh Corp., Japan). Density was measured using the Archimedes method; the phase contents were determined by XRD; translucency was evaluated by a spectrophotometer on a black and white background; flexural strength and fatigue resistance were assessed by the biaxial flexure method; and the microstructure was examined by SEM imaging. We observed that transient thermal stresses were developed during sintering as a result of thermal gradients due to the fast heating and cooling rates adopted by speed firing. Finite element analysis (FEA) was utilized to quantify the magnitude of transient thermal stress. These significant observations highlighted the importance of pre-sintering conditions, especially if the pre-sintered zirconia blocks and discs were intended for speed sintering. Further, our findings showed that the currently recommended speed and high-speed sintering protocols of YSZ resulted in incomplete densification due to the brief dwell time of 5–16 min compared to 120 min in conventional sintering. Subsequently, the entrapped pores resulted in light scattering and reduced optical translucency. Interestingly, residual pores did not affect the flexural strength. The speed sintering protocols for 3–5 mol% YSZ were optimized by proposing higher sintering temperatures, 1550°C and 1580°C, and longer dwelling times, 40 min and 60 min. As a result, SS-1 (1550°C/40 min) for 3YSZ, SS-3 (1580°C/40 min) for 4YSZ, and SS-4 (1580°C/60 min) for 5YSZ was the optimal speed sintering conditions for those compositions, which led to significantly lower properties than the current speed and high-speed sintered YSZ and comparable to the gold standard “conventional sintering.” Finally, we demonstrated that the selected optimal speed sintering protocol for 5YSZ is more fatigue-resistant and exhibits better long-term mechanical stability.Publication ACCURACY OF 3D PRINTED MODELS WITH DIFFERENT DIE SPACING VALUES: AN IN VITRO COMPARISON TO A SOLID MASTER MODEL.(2024-08-30) Papaioannou, MarianthiStatement of the Problem: The accuracy of 3D-printed master models is crucial in prosthodontics, as any inaccuracies can result in poorly fitting restorations, particularly regarding margins, contact points, and occlusal levels. While various factors related to the printing process can influence the accuracy of these models, there is limited evidence on how die spacing in removable dies specifically impacts their precision. Purpose: The goal of this present study is to evaluate the accuracy of 3D-printed Pindex models by assessing the effects of varying die spacing values in comparison to a control solid 3D-printed master model. The null hypothesis is that there is no difference between the solid models with the test groups. Materials & Methods: A control model representing eight prepared teeth was designed using a design software (Modelliere, Zirkonzahn, Italy), exported as an STL file, and printed via additive manufacturing (Pro S , Sprintray,). The test samples, divided into three groups with offset values of 0.1mm(Group A), 0.05mm(group B), and 0.03mm(Group C), were fabricated from the same STL file. Each group consisted of ten samples. Post-processing followed the manufacturer’s guidelines, including alcohol rinsing, air drying, and UVA light curing. Samples were scanned using a laboratory scanner (Dentsply, Sirona) after being coated with a thin layer of titanium oxide powder to eliminate reflections and ensure high-quality data acquisition. The scanned files were then analyzed using Geomagic software, with all data aligned to the control model for comparison. Results: The findings confirmed the null hypothesis, showing no statistically significant differences between the three groups. However, the study revealed a notable difference in the fit of the dies in Group C, with a die spacing of 0.03mm, which exhibited greater deviation from the control model compared to Groups A and B, which showed closer alignment with the solid model. Conclusions: The results provide insights into the impact of die spacing variations on the accuracy of 3D-printed master models, contributing to improvements in digital dental model fabrication. The results provide valuable insights into how variations in die spacing affect the accuracy of 3D-printed master models, contributing to advancements in digital dental model fabrication.Publication Long-term Clinical and Radiographic Healing of Endodontic Microsurgery with Collagen-Based Bone-Filling Material: Comparison of 2D and 3D Healing(2024-08-30) Szu Hua Chiang, DMDABSTRACT Aim: (1) To evaluate the long-term clinical and radiographic periapical and cor:cal bone healing of endodon:c lesions with four-wall defects following endodon:c microsurgery (EMS) using collagen-based bone-filling material, (2) to study collagen-based filling material’s clinical significance and (3) to compare 2D- and 3D- outcome assessments. Methodology: The long-term clinical and radiographic evalua:ons of 58 surgical cases was reported in ‘Periapical Healing Following Endodon:c Microsurgery with Collagen-Based Bone- Filling Material: A Randomized Controlled Clinical Trial by Albagle et al. IEJ 2023 (1). In the preliminary methodology of this study, EMS was performed by calibrated postgraduate endodon:c residents. Before flap closure placement of a collagen-based bone-filling material was randomly assigned to osteotomies as the treatment group, whereas no material was placed in the control group. If necessary, separate osteotomies were created for mul:-rooted teeth. Samples were included only if two osteotomy sites were separated by bone. Each individual osteotomy was considered a sample and randomized. Proceeding with the asymptoma:c 66 endodon:c-origin lesions collected and assessed at the 1-year follow-up evaluated by double blinded endodon:sts examined using periapical (PA) radiographs according to Molven’s criteria 20 for 2D healing, cone beam computed tomography (CBCT) scans in conformity with Penn 3D criteria for 3D periapical healing and RAC/B index for cor:cal plate healing. For follow-up, pa:ents (n = 58) were contacted ini:ally for phone interviews, to determine if symptoms or it needed an extrac:on or re-surgery. Subjects returned for the long-term follow-up appointment. Teeth were assessed for sensi:vity to palpa:on and percussion, mobility, probing depths and symptom as such as presence of intraoral swelling or sinus tract. PA radiographs and CBCT scans of the asymptoma:c teeth were evaluated similarly by three evaluators following Molven and Penn3D evalua:on methods. Results: A total of 39 cases were evaluated radiographically a9er excluding extrac:ons, lost pa:ents, declining to clinical examina:on and one symptoma:c case due to fracture. The follow- up period ranged from 2.78 years to 4.75 years; 17 and 22 cases are in the control and treatment groups, respec:vely. Both control and treatment groups obtained higher success rates according to Molven’s criteria (95.5% and above) than PENN 3D criteria and C-score system. At the 3 year follow-up, the success rates were determined similar between PENN 3D and C-score ranging from 82.4% to 86.4% in both treatment and control groups. Compared to the control group, the Founda:on group obtained higher percentage of healing at year 1 according to Molven’s criteria, PENN 3D, and C-score system. In contrast, the control group had an overall higher improvement in healing rate from year 1 to year 3. The long-term follow-up rate for the study was 75.9%. Conclusions: The long-term evalua:on of the cor:cal plate healing is equal in the control and treatment groups as the observa:on period reached close to 4 years or above. The cri:cal healing 21 period was between 1 year to 3 years, where placement of collagen-based bone-filling material is suggested to accelerate the radiographic healing in two- and three- dimensions.Publication Neurocognitive Impairment and Oral Health Outcomes in Patients with HIV (PWH) On Antiretroviral Therapy (ART)(2024-08-31) Eman ALamodi, BDS; Temitope Omolehinwa, BDS, DScD, DMD; Cagla Akay-Espinoza, MD; Kelly L. Jordan-Sciutto, PhD; Sunday O. Akintoye, BDS, DDS, MS; Eric T. Stoopler, DMD, FDSRCS, FDSRCPSBackground The advent of antiretroviral medication (ART) led to a significant decline in HIV associated morbidity, including the more severe presentations of HIV-associated neurocognitive disorders (HAND). However, milder forms of neurocognitive impairment (NCI) persist. Neurocognitive deficits have also been independently associated with poor dental outcomes, especially in the elderly population. However, there is limited, if any, reports of dental health outcomes in people with HIV (PWH) with NCI. This study was designed to better understand oral health outcomes in PWH with NCI. Methods A cross-sectional pilot study was conducted on 40 participants, comprising 10 healthy controls and 30 PWH. Neurocognition and dental outcomes were assessed in all participants. Neurocognition was evaluated using a computerized neurobehavioral battery (CNB) test. Dental caries was assessed using the Decayed, Missing, and Filled Teeth (DMFT) index, the Decayed and Filled Teeth (DFT) index, and the Missing Teeth (MT) index. Periodontal status was measured through clinical attachment loss, periodontal pocket depth, and the percentage of sites with bleeding on probing (%BOP). Results Mean DMFT, DFT and MT were significantly higher among PWH (p < 0.001, p = 0.02, p = 0.048, respectively) than in control subjects. NCI was present in 4 PWH and 1 control subject. We also noted that among PWH, those with NCI had a higher DMFT index (20.8 versus 18.5) and a significantly higher mean DFT (12.3 versus 8.0) compared to PWH without NCI (p = 0.048). Conclusion Poor oral health, especially dental caries, is a challenge among PWH and moreso among PWH with NCI.Publication Evaluating the Efficacy of Laser-Assisted Endodontic Treatment: Insights from In Vitro Models and In Vivo Studies(2024-08) Mominkhan, DanaObjective: To develop a clinically relevant complex multi-species biofilm model of endodontic infection and evaluate the performance of new laser technologies in vitro and in vivo. Methods: For the in vitro studies, bacterial species were selected based on the literature and the correlation network analysis (CNA) of our collection of 206 root canal samples. Biofilms were developed for 7 and 14 days. Three tooth models (SM, DMK, SMS) were compared using 200 extracted human premolars and four different laser technologies were tested. For the in vivo studies, patients presenting apical periodontitis were selected for treatment using the standard of care (NaOCl, control) or adjunctive laser treatment (test). Outcomes measured included CFU reduction and pain assessment. Results were evaluated using culture, SEM, FISH and CLSM LIVE/DEAD analysis. Data were analyzed using Kruskal-Wallis, PCA and GEE. Results: Tooth models were assessed with E. faecalis biofilms and tested using a multi-species biofilm composed of A. viscosus, F. nucleatum, P. micra, P. nigrescens and S. sanguinis. DMK was the most effective tooth model. EdgePRO™ was the most effective laser in the presenc of NaOCl and LEAP™ in its absence. Fifty-two patients completed the study. CFUs were reduced by both treatments. No differences were observed regarding post-operative pain. Conclusion: The new multi-species biofilm model developed here is a clinically relevant and effective tool to assess new treatments. EdgePRO™ is effective in reducing CFUs of in vitro and in vivo biofilms.Publication Evaluation of Peri-implant Health Status(2024) Kashiwagi, KosukeObjective 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, NoorIntroduction: 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 AbedAlthaqafiDespite 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, NourINTRODUCTION: 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, MHSAbstract 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.