Objectives: The work was to determine the maxillary tissue changes under acrylic and flexible lower tooth supported overdentures. Methods: The study was accomplished on 20 patients; the selected cases were upper completely edentulous and lower tooth supported one. lower overdenture supported with canines bilaterally. The cases randomly split into two groups: Group I; ten patients wear acrylic complete upper denture and acrylic mandibular tooth supported overdenture Group II; ten patients wear flexible complete upper denture and flexible lower tooth supported overdenture. Clinical tests were performed by measuring the soft tissue thickness of superimpose the anterior upper ridge at 2 dots 1 cm and 2 cm on each hand to the midline at time of prosthesis delivery and at 12 months. Also, radiographic evaluations of upper edentulous area estimated at time of prosthesis delivery and at 12 months. Results: there was non-significant increase in upper mucosa thickness in both groups at both points of measurements. Also, both groups showed radiographic bony changes in maxillary ridge. There was significant increase in maxillary bony changes in Group I in compare to Group II. Conclusion: it was concluded that there was slight increase in the thickness of soft tissue above the anterior upper ridge in each sequence. More bone resorption allover region of maxilla was observed in Group I, but there was slight decrease in Group II more than Group I. KEYWORD: Tooth supported overdentures, thermoplastic and acrylic dentures, soft tissue Improvements in the upper edentulous area, upper edentulous area radiographic evaluations
Aim: To evaluate flexural strength (FS) and micro-hardness of poly(methylmethacrylate) (PMMA) denture base material modified with Zirconium oxide (ZrO2), titanium oxide (TiO2) and zinc oxide (ZnO) nanoparticles powder with different concentration (1.5, 3 and 5% ) Subjects and Methods: Test specimens of PMMA of dimensions (65 ×10 × 2.5 mm) were made from heat-cured acrylic resin served as control group Another nine group were made of PMMA containing 1.5, 3, and 5% (w/w) (ZrO2), ( TiO2) and (ZnO) nanoparticles. Two types of mechanical tests were performed on the samples: flexural strength and hardness. Results: Statistical analysis results revealed that non-significant increase in flexural strength of heat cured reinforced with ZrO2 Nps and ZnO Nps for all concentrations. While adding 1.5% and 5% of TiO2 Nps showed significant increase in flexural strength but 3% showed significant decrease values. Results revealed that non-significant decrease in hardness of heat cured reinforced with ZrO2 Nps ,TiO2 Nps, and ZnO Nps for all concentrations except 3% of heat cured reinforced with TiO2 Nps which showed non-significant increase in hardness. Conclusions: It was discovered that adding of 1.5and 5% Tio2 Nps to the used denture base materials would improve the flexural strength of the denture base materials. Also, adding 1.5, 3 and 5 % ZrO2, Tio2, and ZnO Nps reduces the microhardness.Nanotechnology has lately been utilized in the prosthetics scope to material boost objectives (2,3) , which has been confirmed in the research of nanomaterials for enhancing the mechanical characteristics KEYWORDS Flexural strengths, micro-hardness, Zirconium oxide, Titanium oxide and zinc oxide nanoparticles, heat-polymerized acrylic resin.
Aim: estimate flexural strength of strengthened denture base resin by different concentrations of Zirconium oxide nanoparticles (Zro2 Nps), Aluminum oxide nanoparticles (Al2o3 Nps) and Titanium oxide nanoparticles (Tio2 Nps). Subjects and methods: fifty sample were got ready to experimentation of flexural strength together with dimensions 65 length x 10 width x 2.5mm thickness and then these samples were split into 4 series (A, B, C, D) and these groups then partitioned to 3 sub collections (1, 2, and 3) of 5 specimens for each group according to the ratio of Zro2Nps, Al2o3 Nps and Tio2 Nps which were (1%, 2% and 3%) for each type of nanoparticles that were added to heat-cured Poly methyl methacrylate (PMMA). Results: Regardless to metal oxide type, totally the highest mean value was recorded for control group (77.96 MPa). The difference between groups was statistically significant as indicated by ANOVA test (p=<0.0001<0.05) for flexural strength. Conclusions: It was found that there is slight decreasing in transverse strength of PMMA for all concentrations added of Zro2Nps, Al2o3 Nps and Tio2 Nps when compared to control group.
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