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Mohammed M Gad,1 Reem Abualsaud,1 Ahmed Rahoma,2,3 Ahmad M Al-Thobity,1 Khalid S Al-Abidi,1 Sultan Akhtar4 1Department of Substitutive Dental Sciences, 2Department of Restorative Dental Sciences, College of Dentistry, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia; 3Department of Dental Materials, College of Dentistry, Al-Azhar University, Assuit, Egypt; 4Department of Biophysics, Institute for Research and Medical Consultations, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia Background: Polymethyl methacrylate (PMMA) is widely used for the fabrication of removable prostheses. Recently, zirconium oxide nanoparticles (nano-ZrO2) have been added to improve some properties of PMMA, but their effect on the optical properties and tensile strength are neglected.Objective: The aim of this study was to investigate the effect of nano-ZrO2 addition on the translucency and tensile strength of the PMMA denture base material.Materials and methods: Eighty specimens (40 dumbbell-shaped and 40 discs) were prepared out of heat-polymerized acrylic resin and divided into four groups per test (n=10). The control group for each test included unreinforced acrylic, while the test groups were reinforced with 2.5, 5, and 7.5 wt% nano-ZrO2. Acrylic resin was mixed according to manufacturer’s instructions, packed, and processed by conventional method. After polymerization, all specimens were finished, polished, and stored in distilled water at 37°C for 48±2 hours. Tensile strength (MPa) was evaluated using the universal testing machine while the specimens’ translucency was examined using a spectrophotometer. Statistical analysis was carried out by SPSS using the paired sample t-test (p≤0.05). A scanning electron microscope was used to analyze the morphological changes and topography of the fractured surfaces.Results: This study showed that the mean tensile strength of the PMMA in the test groups of 2.5%NZ, 5%NZ, and 7.5%NZ was significantly higher than the control group. The tensile strength increased significantly after nano-ZrO2 addition, and the maximum increase seen was in the 7.5%NZ group. The translucency values of the experimental groups were significantly lower than those of the control group. Within the reinforced groups, the 2.5%NZ group had significantly higher translucency values when compared to the 5%NZ and 7.5%NZ groups.Conclusion: The addition of nano-ZrO2 increased the tensile strength of the denture base acrylic. The increase was directly proportional to the nano-ZrO2 concentration. The translucency of the PMMA was reduced as the nano-ZrO2 increased.Clinical significance: Based on the results of the current study, the tensile strength was improved with different percentages of nano-ZrO2 additions. However, translucency was adversely affected. Therefore, it is important to determine the appropriate amount of reinforcing nano-ZrO2 that will create a balance between achieved properties – mechanical and optical. Keywords: denture base, PMMA, tensile strength, translucency, zirconium oxide nanoparticles

Background: Denture stomatitis has been linked to the adhesion and proliferation of Candida albicans ( C. albicans ) on denture bases, which is a common and recurrent problem in denture wearers. The current study aimed to evaluate the effect of incorporating caffeic acid phenethyl ester (CAPE) into autopolymerized polymethyl methacrylate (PMMA) acrylic resin on C. albicans adhesion, surface roughness, and hardness as well as the correlation between tested properties., Methods: Autopolymerized acrylic resin discs ( N  = 100, 50/ C. albicans adhesion; 50/ C. albicans surface roughness and hardness test) were fabricated in dimensions 15 × 2.5 mm, samples were categorized into 5 groups ( n  = 10) based on CAPE concentrations; unmodified (control), 2.5, 5, 10 and 15% wt of acrylic powder. Specimens were stored in distilled water for 48 h at 37°C. C. albicans adhesion was evaluated via direct culture method. Profilometer and Vickers hardness tester were used for surface roughness and hardness measurement. Post hoc Tukey's HSD with ANOVA test was performed to compare the difference of means amongst groups. P values were statistically significant at ≤0.05., Results: The addition of 2.5% of CAPE to PMMA has significantly reduced C. albicans counts in comparison to higher CAPE concentrations ( p < 0.001). As for surface roughness, it was noticed that it increased with increased CAPE concentrations ( p < 0.0001). While surface hardness decreased as CAPE concentrations increased ( p < 0.0001). All tested properties showed a significant difference amongst groups for C. albicans colony count and surface parameters., Conclusion: The addition of 2.5% of CAPE to PMMA acrylic resin significantly decreased C. albicans count compared to higher CAPE concentrations. CAPE can be used as an adjunct in the prevention of DS by incorporating in the PMMA acrylic resin., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2022 Khalifa S. Al-Khalifa et al.)

Objectives: This study aimed to evaluate denture cleanser effects on color stability, surface roughness, and hardness of PMMA denture base resin reinforced with nano-ZrO 2 ., Materials and Methods: A total of 420 specimens were fabricated of unreinforced and nano-ZrO 2 reinforced acrylic resin at 2.5% and 5%, resulting in 3 main groups. These groups were further subdivided ( n  = 10) according to immersion solution (distilled water, Corega, sodium hypochlorite, and Renew) and immersion duration. Surface roughness, hardness, and color were measured at baseline (2 days- T 0 ) in distilled water and then after 180 and 365 days of immersion ( T 1 & T 2 ) in water or denture cleansing solutions. Data was collected and analyzed using two-way ANOVA followed by Bonferroni post hoc test ( α  = 0.05)., Results: Surface roughness increased significantly after denture cleanser immersion of unmodified and nano-ZrO 2 -modified PMMA materials while hardness decreased ( P < 0.001). The denture cleansers significantly affected the color of both PMMA denture bases ( P < 0.001). The immersion time in denture cleansers significantly affected all tested properties ( P < 0.001). Within denture cleansers, NaOCl showed the highest adverse effects ( P < 0.05) while Renew showed the least adverse effects., Conclusion: Denture cleansers can significantly result in color change and alter the surface roughness and hardness of denture base resin even with ZrO 2 nanoparticles addition. Therefore, they should be carefully used., Competing Interests: The authors declare that there are no conflicts of interest regarding the publication of this paper., (Copyright © 2021 Mohammed M. Gad et al.)

Aim: To investigate the dentists' opinions towards social media (SM) use in daily practice and the expected limitations from its use in Saudi Arabia., Methods: An electronic survey was carried out throughout May-June 2020 among a sample of dentists in Saudi Arabia. The survey covered three parts: the first part covered professional and demographic information, the second part covered the use of mobile phones and SM in dental practice, while the third part assessed dentists' opinion on SM use. Descriptive statistics included frequency distributions and percentages and independent t test/ANOVA test for the relationship between the mean of dentists' opinion towards SM and demographic variables. A p value of 0.05 or less was considered statistically significant., Results: The majority of respondents (80%) believe that SM plays an active role in patients' decisions regarding the selection of a healthcare provider. The mean dentists' opinion scores on the use of SM were significantly lower among participants working more than 50 h per week compared with other participants (p = 0.014)., Conclusion: The majority of sampled dentists believe that SM plays an active role in patients' decisions regarding the healthcare provider's selection. Directed campaigns can help dentists optimize the use of SM for both professional and personal purposes.

This study aimed to investigate the prevalence of partial edentulism, RPD type, design, and components and their frequency of use by patients at the prosthodontic clinics of the College of Dentistry, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia. The prepared surveys, laboratory authorization forms, and images of the RPD metal frameworks on casts were used for data collection. Two calibrated investigators studied the digital photographs to identify the Kennedy classification, type of RPD, major connector, clasp assembly, and other details. Data was collected and analyzed statistically. The results showed that the most common class of partial edentulism was Kennedy class I, whereas class IV was the least ( p <  0.001). Sixty two percent of fabricated RPDs had metal frameworks, whereas 37.2% were frameless. RPI was the most frequently used clasp assembly (38.9%), a significant finding in Kennedy class I( p  < 0.01). The maxillary anteroposterior palatal strap and mandibular lingual plate were the most commonly used major connectors, at 41.2% and 60.8%, respectively. Conclusions: Simple RPD design that accomplishes the treatment objectives as well as proper communication with a well-trained dental technician would promote the success of RPDs., Competing Interests: The authors declare no conflict of interest., (© 2019 The Authors.)

Introduction: Severe pre-transplant pulmonary hypertension (PH) has been associated with adverse short-term clinical outcomes after heart transplantation in relatively small single-center studies. The impact of pre-transplant PH on long-term survival after heart transplantation has not been examined in a large, multi-center cohort., Methods: Adults (≥18 years) who underwent first time heart transplantation in the United States between 1987 and 2012 were retrospectively identified from the United Network for Organ Sharing registry. Pre-transplant PH was classified as mild, moderate, or severe based on pulmonary vascular resistance (PVR), trans-pulmonary gradient (TPG), and pulmonary artery (PA) mean pressure. Primary outcome was all-cause mortality., Results: Data from 26,649 heart transplant recipients (mean age 52±12 years; 76% male; 76% Caucasian) were analyzed. During a mean follow-up of 5.7±4.8 years, there were 10,334 (39%) deaths. Pre-transplant PH (PVR≥2.5 WU) was a significant predictor of mortality (hazard ratio 1.10, 95% confidence interval 1.05-1.14, p<0.0001) in multivariable analysis. However, the severity of pre-transplant PH (mild/moderate vs. severe) did not affect short or long-term survival. Similarly, even in patients who were supported with either a left ventricular assist device or a total artificial heart prior to transplant, severe pre-transplant PH was not associated with worse survival when compared to patients with mild/moderate pre-transplant PH., Conclusion: Pre-transplant PH (PVR≥2.5 WU) is associated with a modest increase in mortality when compared to patients without pre-transplant PH. However, the severity of pre-transplant PH, assessed by PVR, TPG, or mean PA pressure, is not a discriminating factor for poor survival in patients listed for heart transplantation., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

Background: Sudden cardiac death (SCD) has been reported to be a significant mode of death after heart transplantation (HT) in small case series. However, the incidence, timing, and predictors of SCD have not been examined in a large multicenter HT cohort., Objective: The purpose of this study was to examine the incidence, timing, predictors, and temporal trends of SCD after HT., Methods: Adults (≥18 years) who underwent first-time HT in the United States between 1987 and 2012 were retrospectively identified from the United Network for Organ Sharing (UNOS) registry. Patients with sudden cardiac arrest as the primary cause of death constituted the SCD group., Results: Data on 37,492 HT recipients (mean age 51.9 ± 11.7 years, 77% male, 78% Caucasian) were analyzed. During mean follow-up of 6.5 ± 5.7 years, there were 17,324 (46%) deaths, of which 1659 (9.6%) were SCD. On multivariate Cox regression analysis, left ventricular ejection fraction (LVEF) ≤40% (hazard ratio [HR] 3.67, 95% confidence interval [CI] 3.23-4.17, P < .0001), allograft rejection (HR 1.51, 95% CI 1.35-1.70, P < .0001), and donor age (HR 1.17, 95% CI 1.13-1.23, P < .0001) were associated with increased risk of SCD, whereas recipient age (HR 0.90, 95% CI 0.86-0.95, P < .0001) and Caucasian race (HR 0.61, 95% CI 0.54-0.69, P < .0001) were associated with reduced risk. The incidence of SCD has shown no significant temporal improvement since 1987 (log-rank P = .84)., Conclusion: Approximately 10% of deaths after HT are due to SCD. Allograft rejection and LVEF ≤40% are strong predictors of SCD in adult HT patients. Whether implantable cardioverter-defibrillators would reduce mortality in these patients with a relative higher risk of non-SCD remains to be determined., (Copyright © 2014 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)