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Statement of problem How axial displacement may be affected by the mechanical properties and internal discrepancy of a cement-retained implant-supported prosthesis is unclear. Purpose The purpose of this in vitro study was to assess the difference in internal discrepancy and axial displacement according to the prosthesis material in cement-retained prostheses splinting nonparallel implants. Material and methods Computer-aided design and computer-aided manufacture (CAD-CAM) titanium abutments were fabricated for a vertically placed implant and a 15-degree tilted implant. Three types of prostheses, in zirconia, cobalt-chromium (Co-Cr) alloy, and polymethylmethacrylate resin (PMMA), were fabricated (n=10). The internal discrepancy between the CAD-CAM titanium abutment and the prosthesis was measured by using the replica technique. After luting with an interim cement, they were mounted in Type IV gypsum. The specimens were cyclic loaded, and axial displacement of the prosthesis was measured after 3, 10, 100, and 106 cycles. The internal discrepancy and cumulative axial displacement were assessed by using a 3-way analysis of variance and repeated measures analysis of variance (α=.05). Results The internal discrepancy of the prosthesis did not differ based on the prosthesis material (P=.869); however, it was significantly different based on the measurement location, with the occlusal discrepancy (224 ±29 μm) being greater than the axial discrepancy (21 ±10 μm) (P Conclusions Prostheses made with high-elastic moduli materials exhibited less axial displacement than PMMA prostheses, even though the internal discrepancy was not different. Moreover, vertically placed implants presented a greater axial displacement of the prosthesis than implants with angled placement.

Polymethylmethacrylate (PMMA) resin is one of the most commonly used materials for fabricating the base of removable orthodontic appliances. It is known that PMMA resin can promote the adhesion of microbes due to its surface porosity and from long-term use. Vanillin-incorporated PMMA resin has been reported to have antimicrobial effects against Candida albicans. However, the influence of vanillin incorporation on the water sorption and solubility of self-curing orthodontic PMMA resin has not been studied. Objective: To determine the water sorption and solubility of self-curing orthodontic PMMA resin incorporated with different concentrations of vanillin. Materials and methods: Three groups of self-curing orthodontic PMMA resin incorporated with 0.1% and 0.5% vanillin as well as PMMA without vanillin as a control were prepared with ten specimens per group. Water sorption and solubility tests were performed according to ISO 20795-2:2013 specifications. One-way ANOVA and Tukey’s multiple comparison tests at a pResults: All three groups met ISO standard requirements. The means of water sorption values showed insignificant differences among the three groups even though the value of the 0.5% vanillin group tended to decrease. Water solubility of the 0.1% vanillin-incorporated group was not significantly different when compared with the control group whereas that of the 0.5% vanillin-incorporated group exhibited a significant lower value when compared with both control and 0.1% vanillin-incorporated groups. This suggests that increasing concentrations of vanillin would decrease the water solubility of PMMA resin. Conclusion: The incorporation of 0.5% vanillin into self-curing orthodontic PMMA resin could significantly reduce its water solubility and showed a trend of less water sorption property. Even with different vanillin concentrations, the water sorption and water solubility properties of PMMA resin were within the ISO standards. Nevertheless, further studies are recommended to determine the amount of residual monomer present in different concentrations of vanillin-incorporated PMMA resin.

Polymethylmethacrylate (PMMA) resin is the main polymeric material used in removable orthodontic appliances. However, it can promote the adhesion of microbes due to its surface porosity and from long-term use. While vanillin incorporated PMMA resin has been reported to have antimicrobial effects against Candida albicans, the influence of vanillin incorporation on the physical properties of self-curing orthodontic PMMA resin has not been studied. Objective: To determine the flexural strength and flexural modulus of self-curing orthodontic PMMA resin incorporated with vanillin in different concentrations. Materials and methods: Three groups of self-curing orthodontic PMMA with incorporated vanillin concentrations of 0.1%, 0.5% as well as PMMA without vanillin as a control were prepared with ten specimens per group. Flexural strength and flexural modulus were tested by a 3-point bending machine according to ISO 20795-2:2013 specifications. One-way ANOVA and Tukey’s multiple comparison tests at a pResults: The 0.1% vanillin incorporated group met ISO standard requirements (flexural strength = 60.48 MPa, flexural modulus = 1756.60 MPa), while the 0.5% vanillin incorporated group failed to pass this standard (flexural strength = 46.94 MPa, flexural modulus = 1423.49 MPa). The means of both flexural strength and flexural modulus showed significant differences among the three groups. Increasing the concentration of vanillin would decrease the flexural strength and flexural modulus of PMMA resin. Conclusion: The incorporation of vanillin into self-curing orthodontic PMMA resin can affect its physical properties, namely flexural strength and flexural modulus. At a concentration of 0.1% vanillin incorporation, PMMA resin displayed physical properties within the ISO standards.

To provide maxillary and mandibular complete dentures for a patient with severe ridge resorption, the denture space was recorded using the piezography technique. After the piezographic space was scanned, a virtual tooth arrangement and festooning were performed within the space using computer-aided design software. The denture bases were milled from a polymethylmethacrylate resin block using computer-aided manufacturing, and commercially available denture teeth were bonded with resin adhesive. Using the piezography technique described, physiologically appropriate complete dentures were fabricated based on the neutral zone concept.

PURPOSE The aim of the present study was to evaluate the color changes of an autopolymerizing PMMA resin used for interim fixed restorations, reinforced with SiO2 nanoparticles. MATERIALS AND METHODS Silica nanoparticles were blended with the PMMA resin powder through high-energy ball milling. Four shades of PMMA resin were used (A3, B3, C3, D3) and total color differences were calculated through the equations ΔEab= [(ΔL*)2 + (Δa*)2 + (Δb*)2]½ and ΔE00=[ΔL'KLSL2+ΔC'KCSC2+ΔH'KHSH2+RTΔC'KCSCΔH'KHSH]1/2 . Statistically significant differences between ΔEab and the clinically acceptable values of 3.3 and 2.7 and those between ΔE00 and the clinically acceptable value of 1.8 were evaluated with one sample t-test (P

Background The purpose of this in vitro study was to evaluate the impact of the remaining tooth structure on the retention of overdenture cast metal copings. Material and Methods A freshly extracted intact mandibular human canine (length 25 mm) was selected and endodontically treated. An incisal reduction of 4 mm with no ferrule preparation was performed and a post space of 12 mm was created. By using polyvinyl siloxane duplication material and autopolymerizing polymethylmethacrylate resin, ten resin teeth analogs (control group) were obtained. A second set of ten resin teeth analogs (group 1) was created by preparing on the original natural tooth a 360o ferrule design of 1 mm in height and by using the same procedural technique. The canine was further reduced by an additional 1 mm, resulting in a ferrule of 2 mm in height, measured from the initial incisal reduction, thus a third set of ten resin teeth analogs (group 2) was created. For every tooth analog in all groups a dome-shaped metal coping was cast and luted with a glass ionomer cement. All specimens were subjected to tensile load testing until decementation occurred. Results The specimens in the control group exhibited a mean failure load of 87.21 ± 18.26 N, while the 1 mm ferrule group recorded a higher mean failure load of 125.43 ± 8.79 N and the 2 mm ferrule group recorded the highest mean failure load of 146.12 ± 23.38 N. One-way ANOVA revealed significant differences (F= 28.04, p

Aim: The purpose of the study was to evaluate the fracture strength of provisional fixed partial dentures made of autopolymerizing polymethylmethacrylate (PMMA) resin using different types of reinforcement materials to determine the best among them. Materials and Methods: Fifty samples were made (10 samples for each group) with autopolymerizing PMMA resin using reinforcement materials (stainless steel wire: looped and unlooped and glass fiber: loose and unidirectional) as 3-unit posterior bridge. The test specimens were divided into five groups depending on the reinforcing material as Group I, II, III, IV, and V; Group I: PMMA unreinforced (control group), Group II: PMMA reinforced with stainless steel wire (straight ends), Group III: PMMA reinforced with stainless steel wire (looped ends), Group IV: PMMA reinforced with unidirectional glass fibers, and Group V: PMMA reinforced with randomly distributed glass fibers. Universal testing machine was used to evaluate and compare the fracture strength of samples. Comparison of mean ultimate force and ultimate stress was done employing one-way analysis of variance and Tukey's post hoc tests. Results: The highest and lowest mean ultimate force and mean ultimate stress were of Group IV and I, respectively. Tukey's post hoc honestly significant difference multiple comparison for mean ultimate force and stress shows the increase in strength to be statistically significant (P < 0.05) except for the samples reinforced with randomly distributed glass fibers (P > 0.05). Conclusion: Unidirectional glass fibers showed the maximum strength, which was comparable to mean values of both stainless steel wire groups. Low cost and easy technique of using stainless steel wire make it the material of choice over the unidirectional glass fiber for reinforcement in nonesthetic areas where high strength is required.