In Vitro Evaluation of Candida albicans Adhesion and Related Surface Properties of CAD/CAM Denture Base Resins.

OBJECTIVE: The aim of this study was to evaluate the surface roughness, contact angle, and adhesion of Candida albicans to computer-aided designing/computer-aided manufacturing (CAD/CAM) and heat-polymerized (HP) denture base materials. MATERIALS AND METHODS: Specimens were allocated to six groups based on the composition of studied denture base materials, HP acrylic resin, milled resins (AvaDent and IvoCad), and 3D-printed resins (ASIGA, FormLabs, and NextDent). Ten specimens per group were used for each test (n = 10/test). Surface roughness and contact angles were analyzed using profilometer and goniometer, respectively. Adhesion of C. albicans was counted using colony-forming unit (CFU/mL). Means and standard deviations were calculated, and then one-way analysis of variance (ANOVA), followed by Tukey's post hoc test. Correlation of Candida adhesion and surface parameters was determined by using Pearson's correlation analysis. RESULTS: No statistically significant difference was noted in surface roughness between HP, milled, and 3D-printed denture base resins except NextDent, which showed significantly higher roughness in comparison to all other resins (p = 0.001). In terms of contact angle, milled resins had the lowest value, followed by HP, ASIGA, and FormLabs, whereas NextDent showed the highest contact angle (p = 0.001). C. albicans adhesion showed no significant difference between all denture base resins. A positive and significant correlation was found between C. albicans adhesion and contact angle (p = 0.003), while no correlation was reported between C. albicans adhesion and surface roughness (p = 0.523). CONCLUSION: Adhesion of C. albicans was similar in all tested specimens. Surface roughness showed no significant difference between all groups except NextDent, which had the highest value. Milled denture base resins had the lowest contact angle among all groups.

Self-assessment and peer-assessment of the psychomotor skills in preclinical prosthodontics: A prospective study.

INTRODUCTION: Students' self-assessment and peer assessments are essential to understand the rubrics criteria and improve their psychomotor skills. The purpose of this study was to assess the impact of self-assessment score (SAS), peer-assessment score (PAS) and teacher assessment score (TAS) on the final scores of the psychomotor skills of dental students in a preclinical fixed prosthodontics course. MATERIALS AND METHODS: A prospective study included D2 students in a preclinical fixed prosthodontics course for two consecutive academic years from September 2017 to May 2019. Students' performance of various procedures over 14 sessions was assessed by SAS, PAS and TAS. Repeated-measures ANOVA was used to assess differences between the three scores and control charts showed their change over time. Multivariable linear regression was used to assess the association between two outcome variables: TAS and the total preclinical score and the explanatory variables: SAS, PAS, TAS, gender and GPA. The significance level was set at 5%. RESULTS: SAS had a significantly higher mean (80.21) than TAS (79.32) and PAS (78.58). SAS reached higher levels earlier than TAS and PAS. PAS had a stronger association with TAS than SAS (partial eta squared, η2 = 0.17 and 0.13), whereas SAS significantly predicted total preclinical score (p < .0001). CONCLUSIONS: PAS helped develop the skills of dental students during training, while SAS had an impact on their total preclinical score. Different student-centred activities are needed to support students' preclinical training in fixed prosthodontics courses.

Effect of Low Nanodiamond Concentrations and Polymerization Techniques on Physical Properties and Antifungal Activities of Denture Base Resin.

BACKGROUND: Denture base resin has some drawbacks. This study investigated the impact of nanodiamonds (ND) and autoclave polymerization on the surface characteristics, translucency, and Candida albicans adherence in polymethyl methacrylate (PMMA) denture base resin after thermocycling. METHODS: Heat-polymerized PMMA discs (15 × 2 mm) with a total sample size n = 160 were studied. Specimens were categorized into two main groups (N = 80): conventional water-bath-polymerized PMMA (CP/PMMA) and autoclave-polymerized PMMA (AP/PMMA). Each group was subdivided according to the ND concentration into four groups (n = 20): unmodified PMMA as a control, and 0.1%, 0.25%, and 0.5% ND-PMMA. Scanning electron microscopy (SEM) was used to inspect the morphology of the ND and the ND-PMMA mixtures before heat polymerization. The specimens were exposed to thermal cycling (5000 cycles at 5 and 55 °C), then surface roughness was measured with a non-contact optical interferometric profilometer, contact angle with an automated goniometer, and translucency using a spectrophotometer. Colony-forming units (CFU) were used to determine the adherence of Candida albicans cells to the specimens. ANOVA and Tukey post hoc tests for pairwise comparison were utilized for the statistical analysis (α = 0.05). RESULTS: Surface roughness was significantly reduced with ND addition to CP/PMMA (p ˂ 0.001), while the reduction was not statistically significant in AP/PMMA (p = 0.831). The addition of ND significantly reduced the contact angle, translucency, and Candida albicans count of CP/PMMA and AP/PMMA (p ˂ 0.001). The incorporation of ND in conjunction with autoclave polymerization of PMMA showed significant reduction in all tested properties (surface roughness, contact angle and Candida albicans adherence) except translucency (p = 0.726). CONCLUSIONS: ND addition to PMMA and autoclave polymerization improved the surface properties with respect to antifungal activities, while the translucency was adversely affected.

Evaluation of Bacterial Leakage in Platform-Switching Dental Implant with Morse Taper Connection Under Thermocycling and Loading Effects: In Vitro Study.

PURPOSE: The aim of this study was to test in vitro the bacterial microleakage at the Morse taper implant-abutment connection with switched platform subjected to functional load and thermocycling. MATERIALS AND METHODS: A total of 48 Morse taper implant-abutment connections with switched platforms (12 implants per group) were used. The abutments were attached to implants and presented in four groups: group 1, control; group 2, subjected to thermocycling; group 3, subjected to cyclic compressive loading; and group 4, subjected to thermocycling and cyclic compressive loading. All groups were then inoculated in Eppendorf tubes including three types of bacterial suspensions: Enterococcus faecalis, Staphylococcus aureus, and Pseudomonas aeruginosa for 7 and 14 days to detect possibility of bacterial infiltration from outside to the internal chamber of the implant. RESULTS: Implants not exposed to cyclic loading and thermocycling (group 1) and those exposed to thermocycling (group 2) exhibited no infiltration of E faecalis, S aureus, and P aeruginosa from outside to the inner chamber of the implant, while infiltration of P aeruginosa was only observed in implants subjected to cyclic loading only (group 3) and those subjected to cyclic loading in conjunction with thermocycling (group 4). CONCLUSION: Microbial leakage at the implant-abutment connection is influenced by the applied load alone and in combination with thermocycling; however, E faecalis and S aureus did not leak at the implant-abutment connection even under these circumstances. Only P aeruginosa infiltrated inside the implant-abutment connection, which might be caused by its swarming motility.

Two Cases of the Emerging Candida auris in a university hospital from Saudi Arabia.

Candida auris is an opportunistic multidrug-resistant pathogen that was first isolated in 2009 and has since been reported from about 30 countries. In Saudi Arabia, only four cases of C. auris have previously been reported; here, we report two new cases of this infection. Both patients were polymorbid and had long hospitalization periods with recurrent intensive care unit (ICU) admissions. The findings of the tissue/blood cultures and antimicrobial therapy protocols are explained in the case report. Urine culture in both cases was positive for C. auris, and the colonies grew well at 42°C. The fungal isolates were confirmed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The first patient was treated with the recommended dose of caspofungin, but he passed away. The second patient was also planned to be treated with caspofungin, but he passed away before the treatment could be initiated. The present cases further corroborate signs of a growing number of reports of C. auris in patients with high-risk factors, such as hospitalization in ICU, multiple chronic conditions and prolonged antimicrobial treatment exposure. It also highlights the need for hospitals to further improve their infection control practices to prevent nosocomial infections such as C. auris.

Prevalence of CagA and antimicrobial sensitivity of H. pylori isolates of patients with gastric cancer in Egypt.

BACKGROUND: Helicobacter pylori (H. pylori) infection has been recognized as a significant threat for gastric cancer. However, studies that investigated the oncogenic factors and antimicrobial resistance of H. pylori in Egyptian isolates with gastric cancer are rare. The current study aimed to examine: (1) The pattern of antimicrobial resistance of H. pylori isolates of Egyptian gastric cancer patients, and (2) the prevalence of Cytotoxin-associated gene A (CagA). METHODS: Samples were collected from patients with gastric cancer. Isolation of H. pylori was performed using Columbia blood agar supplemented with 10% horse blood, and selective supplement of H. pylori for 3 to 5 days at 37 °C under microaerophilic condition. Isolates were identified by biochemical traits of H. pylori: oxidase, urease and catalase tests. Antimicrobial susceptibility of H. pylori isolates was examined against five antimicrobial agents using disc diffusion method. After that, extraction of DNA and Polymerase Chain Reaction (PCR) were performed to amplify the target genes. RESULTS: Twelve samples were collected from six males and six females Egyptian patients with cancer with an age range from 22 to 65 years. These cases are scarce and samples were collected over a period of almost eleven months. All isolates were confirmed as positive H. pylori through colony morphology and biochemical tests. The most effective antibiotic found was ciprofloxacin whereas all isolates showed resistance to metronidazole and erythromycin. The target CagA oncogene gene with expected product size was reported and seven (out of twelve) isolates (58%) were identified as CagA positive. CONCLUSION: The current study is unique in two main aspects. First, it reported the pattern of antimicrobial susceptibility and prevalence of CagA gene in H. pylori from Egyptian patients. Second, it exclusively recruited isolates from gastric cancer patients which were confirmed by clinical and laparoscopic examination. The moderately high prevalence of CagA gene in Egyptian cancer patients calls for more vigilance against that oncogene.