A Special Design to Facilitate Retrieval of Cement-Retained Zirconia-Based Implant-Supported Restorations

Statement of the Problem: Retrieval of cement-retained implant-supported restorations is challenging in cases of screw loosening or periodontal problems. Purpose: The purpose of this study was to evaluate the effect of the screw access hole on the fracture resistance of zirconia-based cement-retained restorations with and without an access opening. Materials and Method: In this in vitro study thirty-three cement-retained implant-supported zirconia-based molar crowns were fabricated and divided into 3 groups (n=11). As the control group, group 1 consisted of conventional cement-retained crowns. Group 2 comprised conventional cement-retained crowns in which a hole was created in the location of the screw. Group 3 consisted of cement-retained crowns in which a ledge was created in the location of the screw access channel. The specimens were cemented to their abutments and their access openings were filled with composite resin. A compressive load was applied to the specimens using a universal testing machine until they fractured. The mean fracture resistance values of the samples were compared by using the one-way ANOVA and Tamhane post-hoc test (a=0.05). Results: The mean fracture resistance values were 1270.18± 12.67 N in group 1 (the control group), 960.09±210.67 N in group 2 (conventional), and 1357.81±361.68 N in group 3 (the special design). The fracture resistance value was higher in the special design group than that of the conventional design (p= 0.018) and the fracture resistance value of the conventional design group was less than that of the control group (p= 0.042). No statistically significant difference was detected between the control group and the special design group in fracture resistance values. Conclusion: Preparing a screw access hole in cement-retained implant-supported zirconia-based crowns decreased the fracture resistance of the restoration. Designing a ledge in the zirconia framework around the access hole may increase the fracture resistance of the restoration

Tensile Bond Strength of Three Custom-made Tooth-Colored Implant Superstructures to Titanium Inserts

Statement of the Problem: Hybrid abutments are made of a titanium implant insert and a ceramic component. The tensile bond strength between the titanium implant insert and the ceramic component is not still clearly known. Purpose: This in vitro study aimed to compare the tensile bond strength of the titanium insert to ceramic components made of milled lithium disilicate, milled zirconia, and pressable lithium disilicate. Materials and Method: To standardize the shape and dimension of the ceramic components, a single computer-aided design/computer assisted manufacturing (CAD/CAM) superstructure was designed with Dental Designer software. Based on this model, CAD milled zirconia (Zr), CAD milled Lithium disilicate (CAD-LD) and heat-pressed lithium-disilicate (H-LD) superstructures were fabricated (n=10 per group). They were bonded to the titanium inserts by using self-adhesive resin cement. The prepared superstructure-titanium insert complexes (hybrid abutments) were screwed into the implants with 35 Ncm torque. The tensile bond strength of the ceramic superstructures to the titanium inserts were recorded by the universal testing machine with a crosshead speed of 2 mm/min. The data were analyzed by using one-way ANOVA and Tamhane post-hoc test (p< 0.05). Results: The mean±SD of tensile bond strength was 328.50±30.4 N in CAD-LD, 257.30±23.8 N in H-LD, and 242.20±21.2 N in Zr groups. One-way ANOVA revealed the groups significantly different in terms of the tensile bond strength (p< 0.001). Tamhane post-hoc test showed a significant difference between the CAD-LD and the two other groups (p<0.001); however, no statistically significant difference was detected between the H-LD and Zr groups (p= 0.39). Conclusion: It can be concluded that the CAD-LD has higher bond strength to titanium insert compared with the H-LD and Zr groups. Therefore, they might be clinically more beneficial in high-esthetic areas

Human Herpesvirus Detection in Removable Denture Wearers’ Saliva Compared to Dentate Cases

The oral cavity is a complex ecosystem with numerous opportunistic microbial infections

Co-Infection Rates between SARS-CoV-2 and RSV in Oropharyngeal, Nasopharyngeal Aspirate and Saliva Samples of COVID-19 Patients, Shiraz, South of Iran

Statement of the Problem: Determining the prevalence of respiratory viruses' coinfection with coronavirus disease 2019 (COVID-19) is essential to defining its true clinical influence.Purpose: This study aimed to evaluate co-infection rates between severe acute respiratory syndrome–related coronavirus 2 (SARS-CoV-2) and respiratory syncytial virus (RSV) in infected patients in Shiraz, south of Iran.Materials and Method: In a cross-sectional descriptive study, oropharyngeal, nasopharyngeal aspirate (NPA), and saliva samples of 50 COVID-19 patients who were referred to Ali-Asghar hospital (Shiraz, Iran) from March to August 2020, were collected. A control group consisted of age and sex-matched healthy participants. The nasopharyngeal and oropharyngeal aspirates were collected by sterile swabs. All cases were hospitalized, and all SARS-CoV-2 patients had a fever and respiratory symptoms. The samples were packed in a vial with 1 mL of transport medium and transported to the Valfagre specialty laboratory, where they were tested for RSV using a real-time polymerase chain reaction (PCR).Results: 100 nasopharyngeal/oropharyngeal aspirates and saliva samples including 50 healthy controls (24 females, 26 males) and 50 COVID-19 patients' samples (27 males and 23 females) were studied. There was no significant difference regarding age as well as gender between both groups (P>0.05). None of the healthy subjects was infected with RSV; however, 5(10%) patients from COVID-19 group were infected with the RSV virus. Chi-square test did not show a significant difference between RSV infection in COVID-19 patients and healthy subjects.Conclusion: The outcome of present research showed that concurrent RSV with COVID 19 infection might be seen in hospitalized patients in Shiraz Southwest of Iran. For more reliable findings, further research on bigger populations, including more pathogens in several places around the country, and considering the severity of symptoms is required

Intratumoral pan-ErbB targeted CAR-T for head and neck squamous cell carcinoma: interim analysis of the T4 immunotherapy study

Background: Locally advanced/recurrent head and neck squamous cell carcinoma (HNSCC) is associated with significant morbidity and mortality. To target upregulated ErbB dimer expression in this cancer, we developed an autologous CD28-based chimeric antigen receptor T-cell (CAR-T) approach named T4 immunotherapy. Patient-derived T-cells are engineered by retroviral transduction to coexpress a panErbB-specific CAR called T1E28ζ and an IL-4-responsive chimeric cytokine receptor, 4αβ, which allows IL-4-mediated enrichment of transduced cells during manufacture. These cells elicit preclinical antitumor activity against HNSCC and other carcinomas. In this trial, we used intratumoral delivery to mitigate significant clinical risk of on-target off-tumor toxicity owing to low-level ErbB expression in healthy tissues. // Methods: We undertook a phase 1 dose-escalation 3+3 trial of intratumoral T4 immunotherapy in HNSCC (NCT01818323). CAR T-cell batches were manufactured from 40 to 130 mL of whole blood using a 2-week semiclosed process. A single CAR T-cell treatment, formulated as a fresh product in 1–4 mL of medium, was injected into one or more target lesions. Dose of CAR T-cells was escalated in 5 cohorts from 1×107−1×109 T4+ T-cells, administered without prior lymphodepletion. // Results: Despite baseline lymphopenia in most enrolled subjects, the target cell dose was successfully manufactured in all cases, yielding up to 7.5 billion T-cells (67.5±11.8% transduced), without any batch failures. Treatment-related adverse events were all grade 2 or less, with no dose-limiting toxicities (Common Terminology Criteria for Adverse Events V.4.0). Frequent treatment-related adverse events were tumor swelling, pain, pyrexias, chills, and fatigue. There was no evidence of leakage of T4+ T-cells into the circulation following intratumoral delivery, and injection of radiolabeled cells demonstrated intratumoral persistence. Despite rapid progression at trial entry, stabilization of disease (Response Evaluation Criteria in Solid Tumors V.1.1) was observed in 9 of 15 subjects (60%) at 6 weeks post-CAR T-cell administration. Subsequent treatment with pembrolizumab and T-VEC oncolytic virus achieved a rapid complete clinical response in one subject, which was durable for over 3 years. Median overall survival was greater than for historical controls. Disease stabilization was associated with the administration of an immunophenotypically fitter, less exhausted, T4 CAR T-cell product. // Conclusions: These data demonstrate the safe intratumoral administration of T4 immunotherapy in advanced HNSCC

Application of numerical simulation in determining the position and dimensions of weep hole of concrete channel under different groundwater levels

One of the most important problems of irrigation networks is damage to the concrete's canal, which resulted from uplift forces in many cases. The uplift force is created due to the lack of control of the hydrostatic pressure of groundwater on the side wall and the bottom of the canal. The aim of this study is to investigate the position and dimensions of weep hole in the floor and side walls of the concrete channel and its effect on the of reverse leakage flow, uplift forces and hydraulic gradient in different levels of groundwater. For this purpose, a concrete channel with hypothetical geometry over the permeable foundation was simulated by Seep/W software. The variables of the study included dimensions and different positions of weep hole under three different levels of groundwater.The results showed that in all dimensions of weep hole, increasing groundwater depth increase the linear reverse leakage flow rate into the concrete channel and the exist hydraulic gradient. Also, in all weep holes, increasing the diameter reduces the uplift force. If two weep holes are used, the reverse leakage flow into the canal and the uplift forces are respectively more and less than a weep hole. In other words, the placement of two weep holes at positions N=6 and 7 showed a good performance in terms of uplift forces and inverse leakage flow. If two weep holes were placed in positions N=2 and 3, it had the best performance in terms of the exist hydraulic gradient

The Effect of Multiple Firings on the Shear Bond Strength of Porcelain to a New Millable Alloy and a Conventional Casting Alloy

This study compared the effect of multiple firings on the shear bond strength (SBS) of porcelain to the new millable alloy (Ceramill Sintron) and a conventional casting alloy (4-all). Thirty-six cylindrical cores (6.8 × 9 mm) were made of millable and castable alloy through CAD/CAM and casting techniques, respectively (n = 18). In the center of each bar, a 4 × 4 × 2-mm shot of porcelain was fused. Having divided each group into 3 subgroups based on the number of firing cycles (3, 5, 7), the specimens were fixed in a universal testing machine and underwent a shear force test (1.5 mm/min crosshead speed) until fractured. Then the SBS values (MPa) were calculated, and the failure patterns were microscopically characterized as adhesive, cohesive, or mixed. Two-way ANOVA statistical test revealed that the number of porcelain firings had no significant effect on the SBS of any of the metal groups (p = 0.1); however, it was statistically higher in the millable group than the castable group (p &lt; 0.05). Moreover, detecting the mixed failure pattern in all the specimens implied that the multiple firings had no significant effect on the failure pattern. The multiple porcelain firings had no significant effect on the SBS of porcelain to neither the millable nor castable alloys

Evaluating the prevalence of temporomandibular joint abnormalities in postmenopausal women

Regarding the results from various and diversereports on the relationship betweensex hormones, especially estrogen, and theprevalence of TMD and its associated symptoms, it is quiteclear that there are very contradictory and misleading resultson the role of estrogen in the incidence of TMD andits associated symptoms in women before puberty, duringpuberty, before menopause, during and after menopause,which call for more quantitative and qualitative studies tobe conducted. Therefore, we decided to conduct a studywith the aim of evaluating the relationship between thepresence of menopause and its absence with the prevalenceof clinical symptoms of temporomandibular jointproblems in patients requiring prosthesis who visited theDental Prosthetics Department of School of Dentistry ofShiraz University. This is a cross-sectional, descriptive andanalytical study. In this study, 140 women aged 45-55years were examined. Of these, 71 were postmenopausalwomen and 69 were non-menopausal. These subject hadno history of trauma, jaw abnormalities and orthodontics.The Helkimo&lsquo;s clinical index was used to measure theseverity of TMJ dysfunction, and the data obtained wereanalyzed using Chi-square and Mann-Whitney tests andthe statistical software of SPSS. The mean age for nonmenopausalwomen was 46.87 and for postmenopausalwomen was 51.43. Among the symptoms examined, therewas no significant relationship in the range of motionof mandible (P&lt;0.187), however, the rest were significant.The most common symptom in postmenopausal womenwas dysfunction in TMJ function (33.3). This study showedthat TMJ problems are one of the complications associatedwith menopause; therefore, this complication should beconsidered along with other problems such as joint arthritisand osteoporosis that are more prevalent during menopausephase and middle age, and appropriate dentaltreatments should be perform with respect to this issue

Evaluation of mandibular inferior cortex changes in patients candidate for liver and kidney transplantation using panoramic view

Background: The number of patients with chronic liver failure (CLF) or chronic kidney disease (CKD) referred to dental clinics are increasing. However, there are few studies about the effect of these diseases on jaw bones. Objectives: The aim of this study was to evaluate the inferior mandibular cortex changes of the patients with CLF and CKD that are candidate for liver and kidney transplantation, in panoramic views. Patients and Methods: Panoramic radiographs were obtained from 83 patients with a history of CLF and 43 patients with CKD who were undergoing the assessment for transplantation and also 126 control cases. The mean was calculated for the width of inferior mandibular cortex. The relationship between the thicknesses of the inferior mandibular cortex with the duration of disease was determined using Pearson’s correlation coefficient test. T and chisquare tests were used for evaluating the inferior cortex of the mandible according to age and sex, respectively. Results: Compared with the control group, the means of the cortical thickness in CLF and CRF patients were significantly different (P < 0.001). There was a significant relationship between cortical thickness and gender in CLF (P = 0.007) and CRF patients (P = 0.029). Neither the duration of the disease and nor age was associated with mandibular thickness changes in CLF and CRF patients (P = 0.79). Thickness of the inferior mandibular cortex in premolar area was more than that in molar area and thickness of molar was greater than that of the mandibular angle in CKD and CLF patients. This latter was similar to that in normal subjects. Conclusion: Compared with normal population, a decrease in the thickness of inferior mandibular cortex is observed in CKD and CLF patients. This decrease is not affected by age and duration of the disease but is meaningfully related to sex, especially females