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Statement of problem Whether the addition of different antifungal nanoparticles to denture base materials may affect physical or esthetic properties of the resulting nanocomposite is unclear. Purpose The purpose of this in vitro study was to determine how a new method of adding antifungal nanofiller affects the properties of the processed nanocomposite denture base material. Material and methods Heat-polymerized acrylic resin specimens were prepared according to each test specification. Zirconium dioxide nanoparticles (ZrO2NPs) and silver nanoparticles (AgNPs) were added in 0.5, 1.0, and 1.5% of acrylic resin powder. The specimens were divided into 2 groups according to the acrylic resin packing method: 1 layer packed conventionally in one step and 2 layers packed in 2 steps, first with unmodified acrylic resin and then by a thin layer of modified acrylic resin before the final closure. The control group was made of unaltered acrylic resin in 1 step. Flexural strength (FS), translucency, and surface roughness (Ra) were measured. A microbial assay was performed by using the direct culture and slide count methods. Three-way ANOVA and Tukey post hoc tests were used to identify statistical differences among groups (α=.05). Results The addition of ZrO2NPs and AgNPs in the 1- or 2-layer specimens reduced Candida albicans adhesion (P .05), while other AgNP groups exhibited increased surface roughness (P Conclusions The addition of ZrO2NPs in the double-layer technique decreased Candida adhesion and improved FS without affecting surface roughness, while AgNPs decreased Candida adhesion and FS and increased surface roughness. Both nanofillers decreased the translucency except 0.5% ZrO2NPs, which did not change translucency when applied in 2 layers.

Purpose This study aimed to evaluate the repair strength of a newly introduced repair technique involving zero-gap repair width. Materials and methods A total of 36 rectangular prism specimens with dimensions of 64 × 10 × 3.3 mm were prepared from heat-polymerized acrylic resin. Nine specimens were kept intact. The other specimens were sectioned into halves and modified to create repair gaps of 2.5-mm beveled (2.5B) as control, 0-mm beveled (ZB), and 0-mm inverse bi-beveled (ZIBB). The ZIBB group was prepared with a V-shaped internal groove on both halves (repair tunnel), while the intaglio and cameo surfaces were kept intact except for two small holes at the cameo surface for repair resin injection. The 2.5B and ZB groups were repaired conventionally while the ZIBB group was repaired by injecting repair resin into the tunnel through one of the holes until excess material oozed from the other hole. Repaired specimens were thermally cycled at 5 and 55°C for 10,000 cycles with 1 min dwell time. A 3-point bending test was conducted using a universal testing machine for flexural strength and elastic modulus measurement. Kruskal-Wallis/Mann-Whitney tests and ANOVA/post hoc Tukey tests were applied for data analysis (α = 0.05). Results The flexural strength of repaired specimens was substantially lower than that of intact specimens, and significant differences were present between repaired groups (p ˂ 0.05). ZB and ZIBB had higher flexural strength (p ˂ 0.001) and elastic modulus (p ˂ 0.05) than 2.5B. Among the ZB and ZIBB groups, ZB showed the highest flexural strength, and ZIBB had the highest elastic modulus. Conclusion The closed repair technique improved the flexural strength and elastic modulus of repaired acrylic denture base.

PURPOSE: The additions of zirconium oxide nanoparticles (nano-ZrO2 ) to denture base materials have produced nanocomposites with satisfactory properties, although there is a lack of research investigating the effects of denture cleansers on these materials. This study aimed to evaluate the effect of denture cleansers on the flexural strength of denture base materials modified with nano-ZrO2 . MATERIALS AND METHODS: A total of 270 specimens were fabricated from pure and nano-ZrO2 reinforced acrylic resins at 2.5% and 5%, resulting in 3 main groups. The groups were further divided into subgroups (n=10) according to immersion solution (distilled water, Corega, sodium hypochlorite, and Renew) and immersion duration. Flexural strength was measured at baseline (T0 ) in distilled water and after 180 and 365 days of immersion (T1 and T2 ) in denture cleansers. Data were collected and analyzed using repeated measure ANOVA and Bonferroni post hoc tests (α=0.05). RESULTS: The flexural strength of the nano-ZrO2 modified denture base material decreased significantly after immersion in different denture cleansers at different immersion durations in comparison to baseline (T0 ) (P

This study assessed the impact of surface treatments and repair resin reinforcement with zirconium oxide nano-particles (nano-ZrO2) on flexural strength (FS) of repaired denture base. A total of 320 heat-polymerized acrylic resin specimens were prepared and sectioned creating 2-mm gap. According to repair surface treatment, specimens were distributed into four groups: I) methyl methacrylate (M); II) alumina-blasted (AB); III) AB+silane coupling agent (SC); and IV) AB+methacrylate based composite bonding agent (MA). Groups were subdivided into 4 (n=20) according to nano-ZrO2 concentration (0, 2.5, 5, 7.5 wt%). Half the specimens were thermo-cycled before testing. FS was determined by three-point bending test. Statistical analysis was done using ANOVA and Tukey-Kramer multiple comparison tests, with α=0.05. Alumina-blasting+(SC) or (MA) significantly increased FS of repaired specimens compared to control (p

Objective The current study was designed to assess the bonding strength of EndoSeal MTA and AH Plus sealers after using three irrigation protocols as follows: (1) 17% Ethylenediamine tetraacetic acid, (2) 7% maleic acid, and (3) 37% phosphoric acid. Materials and Methods Push-out bond strength was evaluated for 60 middle root slices of 1-mm thickness each. They were horizontally cut from freshly extracted single-rooted human teeth. A hole in the root canal was made using a carbide round bur of 1.1 mm in diameter in a middle third root slice. Specimens were dipped in 2.5% NaOCl, and then they were grouped into three groups; G1: 17% EDTA, G2: 7% maleic acid, and G3: 37% phosphoric acid as a final irrigant for 3 minutes. Each group was subdivided into two subgroups, according to the type of sealer, either EndoSeal MTA or AH Plus. Statistical Analysis After the full set of the sealer, the bond strength was evaluated with the push-out test by applying a force to each slice using a plunger with a 1-mm diameter. The one-way Tukey's post hoc test, analysis of variance (ANOVA) test, and Student's t-test were utilized to gather data and statistically evaluate it. Results The irrigation protocol used exhibited significant influence on the bond strength of EndoSeal MTA and AH Plus sealers. AH Plus sealer subgroups showed the highest bond strength with 7% maleic acid, followed by 37% phosphoric acid, and 17% EDTA. While in the EndoSeal MTA sealer subgroups, the highest bond strength was shown with the 17% EDTA followed by 7% maleic acid and 37% phosphoric acid, respectively. Conclusion The present study revealed that the type of the final irrigant significantly impacts the bond strength of the sealer used. The AH Plus sealer bond strength was improved by using the 7% maleic acid as a final irrigant. In contrast, the EndoSeal MTA sealer showed the best results with the 17% EDTA as a final irrigant.

Statement of Problem. Novel polymethyl methacrylate (PMMA) containing zirconium dioxide nanoparticles (nano-ZrO2) was suggested as a denture base material but there is a lack of information regarding denture cleanser effects. Objectives. This study aimed to evaluate denture cleanser effects on color stability, surface roughness, and hardness of PMMA denture base resin reinforced with nano-ZrO2. Materials and Methods. A total of 420 specimens were fabricated of unreinforced and nano-ZrO2 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-T0) in distilled water and then after 180 and 365 days of immersion (T1 & T2) 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-ZrO2-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 ZrO2 nanoparticles addition. Therefore, they should be carefully used.

The additions of zirconium oxide nanoparticles (nano-ZrOA total of 270 specimens were fabricated from pure and nano-ZrOThe flexural strength of the nano-ZrODenture cleansers can significantly affect the flexural strength of nano-ZrO

Purpose: The current study was conducted to determine the effect of hybrid reinforcement with zirconium oxide nanoparticles (NZ) and glass fibers (GF) on the tensile strength of denture base resin. Materials and methods: Different ratios of NZ/ GF were added into resin at a fixed concentration of 5% by weight. For each formulation (one control and 7 experimental groups), ten specimens were prepared in a dumbbell shape using a stainless steel mold. Tensile strength was evaluated by using a universal testing machine. Scanning electron microscope (SEM) was used to study the fractured surfaces. Results: Tensile strength of the specimens reinforced with NZ/GF in varying ratios was found to be higher than that of the control group. Among the hybrid groups, the specimens reinforced with 50%NZ-50%GF showed the highest tensile strength. SEM fractographs showed multiple lamellae displayed surface, which is characteristic of strong material. Weak adhesion and pull out of fibers from the matrix were seen in high concentration GF. Conclusion: The incorporation of 50%NZ-50%GF into acrylic denture base appeared to improve the tensile strength.

Purpose : The purpose of this study was to evaluate the flexural strength of the acrylic denture base material modified with different concentrations of henna. Materials and Methods: Sixty heat polymerized acrylic resin specimens were fabricated in dimensions 65×10×2.5 mm according to ADA specifications #12. Specimens were divided according to henna concentrations into 6 groups. One control group without henna addition while the other five groups were processed by adding henna in concentrations 1%, 2.5%, 5%, 7.5% and 10% of acrylic powder. After processing, specimens were finished, polished, and stored in distilled water at 37 oC for 48±2 hours prior to testing. The three-point bending test was used to measure the flexural strength using universal testing machine. The morphology of the fractured specimens was studied under a scanning electron microscopy (SEM). The independent sample t-test was used and p ≤ 0.05 was considered statistically significant. Results: The flexural strength significantly decreased with henna addition to PMMA denture base material ( P

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

To evaluate the effect of repair gap width on the flexural strength and impact strength of a repaired acrylic denture with and without thermal cycling.A total of 240 heat-polymerized acrylic resin specimens were fabricated in dimensions of 65 × 10 × 2.5 ± 0.2 mm and 55 × 10 × 10 ± 0.2 mm for flexural strength and impact strength testing, respectively. All specimens were sectioned into halves then divided into 6 groups according to repair gap width (n = 10). The repair gap of the control group was 2.5 mm at the base, while the repair gaps of the test groups were prepared as 2.0, 1.5, 1.0, 0.5, and 0 mm at the base. All specimens were prepared with a 45° bevel joint. Each specimen was placed into the mold that retained the original length of the specimen and modified only the repair gap, which was packed with repair resin. After polymerization, specimens were finished and polished, and half of the specimens were thermal cycled for 5000 cycles. Three-point bending test and Charpy impact test were used to determine the flexural strength and impact strength, respectively. ANOVA and Tukey's HSD test were used for statistical analysis, where α was set at 0.05.Decreasing repair gap significantly increased the flexural strength in comparison to control group (p0.05); 0.5-mm repair gap showed the highest flexural strength values. Changing the repair gap significantly increased the impact strength of groups 2.0- and 1.5-mm (p0.05). Thermal cycling significantly decreased the flexural strength of all tested groups as well as impact strength for groups with wide repair gaps (2.5-, 2.0-, and 1.5-mm) (p0.05), while other tested groups had nonsignificant effect on impact strength (p0.05).Decreasing repair gap increased the flexural and impact strengths of repaired acrylic resin. A repair gap of 0-, 0.5-, or 1.0-mm with beveled repair surface is recommended to improve repair strength and overcome the drawbacks of increased amounts of autopolymerized repair resin.

Background Repeated fracture of the denture base is a common problem in prosthodontics, and it represents a nuisance and a time sink for the clinician. Therefore, the possibility of increasing repair strength using new reinforcement materials is of great interest to prosthodontists.

Objective: The objective of this study was to measure the push-out bond strength of three types of mineral trioxide aggregate (MTA) materials in root dentin. Methods: The study was carried out at the College of Dentistry, Imam Abdulrahman Bin Faisal University from March 2014 to January 2015. Thirty extracted maxillary central incisors were selected, instrumented, irrigated, and randomly assigned into three groups (n = 10): Group 1 - Ortho MTA; Group 2 - MTA Angelus; and Group 3 - ProRoot MTA. Materials were mixed following the manufacturers’ recommendations and canals were filled. Teeth were stored in distilled water for 6 months. The push-out bond strength was evaluated using 2-mm thick coronal root sections. The data were analyzed with one-way ANOVA and Tukey-Kramer multiple comparison tests statistically significant at P < 0.05. Results: The mean bond strength values were 68.69 ± 29.63 MPa for Ortho MTA, 42.54 ± 32.78 MPa for MTA Angelus, and 72.75 ± 26.27 MPa for ProRoot MTA groups. There were no significant differences between the bond strengths of tested materials (P > 0.05). Conclusion: Ortho MTA, MTA Angelus, and ProRoot MTA materials showed similar push-out bond strength values in root dentin.

This study is aimed at evaluating the hybrid reinforcement effects of zirconium oxide nanoparticles (nano-ZrO2) and glass fibers (GFs) at different ratios on the flexural and impact strengths of a polymethylmethacrylate (PMMA) denture base. A total of 160 specimens were fabricated from heat-polymerized acrylic resins using the water bath technique. For the control group, the specimens did not receive any additions; for the test group, different concentrations of nano-ZrO2/GFs at 5% of the PMMA polymer were added. The concentrations of nano-ZrO2/GFs were as follows: 5%–0%, 4%–1%, 3%–2%, 2.5%–2.5%, 2%–3%, 1%–4%, and 0%–5%. The flexural strength was measured using the three-point bending test. The impact strength was measured using the Charpy impact test. Results were tabulated and analyzed using one-way analysis of variance (ANOVA) and the Tukey–Kramer multiple comparison test (p ≤ 0.05). The flexural and impact strengths of PMMA-nano-ZrO2 + GF composites were significantly improved when compared with those of pure PMMA (p < 0.05). The maximum flexural strength (94.05 ± 6.95 MPa) and impact strength (3.89 ± 0.46 kJ/m2) were obtained with PMMA (2.5%)/nano-ZrO2 + 2.5% GF mixtures and could be used for removable prosthesis fabrication.

The current study evaluated the effects of autoclave polymerization both with and without glass fiber (GF) reinforcement on the surface roughness and hardness of acrylic denture base material. Ninety disc specimens (30×2.5 mm) were prepared from Vertex resin and divided according to polymerization techniques into a water bath, short and long autoclave polymerization groups. Tested groups were divided into three subgroups according to the GF concentration (0, 2.5, and 5 wt%). Profilometer and Vickers hardness tests were performed to measure surface roughness and hardness. ANOVA and Tukey-Kramer multiple comparison tests analyzed the results, and p≤0.05 was considered statistically significant. Autoclave polymerization significantly decreased the surface roughness and increased the hardness of acrylic resin without GF reinforcement (p

Background Repeated fracture of the denture base is a common problem in prosthodontics, and it represents a nuisance and a time sink for the clinician. Therefore, the possibility of increasing repair strength using new reinforcement materials is of great interest to prosthodontists. Aim of the study This study aimed to evaluate the effects of incorporation of zirconia nanoparticles (nano-ZrO2) on the flexural strength and impact strength of repaired polymethyl methacrylate (PMMA) denture bases. Materials and methods One hundred eighty specimens of heat-polymerized acrylic resin were fabricated (90 for each test) and divided into three main groups: one control group (intact specimens) and two groups divided according to surface design (45° bevels and butt joints), in which specimens were prepared in pairs to create 2.5 mm gaps. Nano-ZrO2 was added to repair resin in 2.5 wt%, 5 wt%, and 7.5 wt% concentrations of acrylic powder. A three-point bending test was used to measure flexural strength, and a Charpy-type test was used to measure impact strength. Scanning electron microscopy was used to analyze the fracture surfaces and nano-ZrO2 distribution. The results were analyzed with a paired sample t-test and an unpaired t-test, with a P-value of ≤0.05 being significant. Results Incorporation of nano-ZrO2 into the repair resin significantly increased flexural strength (P