Objective:The objective was to investigate the effect of silver nanoparticles (AgNPs) incorporation on viscoelastic properties of acrylic resin denture base material.Materials and Methods:A total of 20 specimens (60 × 10 × 2 mm) of heat cured acrylic resin were constructed and divided into four groups (five for each), according to the concentration of AgNPs (1%, 2%, and 5% vol.) which incorporated into the liquid of acrylic resin material and one group without additives (control group). The dynamic viscoelastic test for the test specimens was performed using the computerized material testing system. The resulting deflection curves were analyzed by material testing software NEXYGEN MT.Results:The 5% nanoparticles of silver (NAg) had significantly highest mean storage modulus E’ and loss tangent Tan δ values followed by 2% NAg (P < 0.05). For 1% nanosilver incorporation (group B), there were no statistically significant differences in storage modulus E’, lost modulus E” or loss tangent Tan δ with other groups (P > 0.05).Conclusion:The AgNPs incorporation within the acrylic denture base material can improve its viscoelastic properties.

Objective. To investigate the influence of reproduction of different thickness and palatal rugae materials on complete dentures speech using Computerized Speech Lab (CSL) (spectrogram). Materials and Methods. Three completely edentulous male patients (aged 50–60 years) were selected for reading a paragraph. Twelve upper dentures were constructed, four for each patient. The patients' speech groups were divided into five groups, Group I: patients without dentures; Group II: patients rehabilitated with conventional acrylic dentures; Group III: patients with conventional acrylic dentures with rugae reproduction; Group IV: patients with dentures with metallic framework of minimal thickness and direct ragged metallic palatal surface at rugae area; Group V: patients with dentures with palatal rugae constructed from resilient acrylic resin material with thickness less than conventional denture. Speech samples were recorded after insertion of each denture for groups using Computerized Speech Lab (CSL) (spectrogram). The sounds selected were lingopalatal /s/z/sh/t/d/ and /l/. Results. Group III produced high mean significant difference with /sh/t/ sound. For Group IV, the difference was noticed with /s/z/sh/t/ and /d/ sounds, while for Group V the difference was shown with /z/l/ sound (P < 0.05). Conclusion. It is recommended to reproduce the rugae area in complete denture because the phonetic quality of complete denture with rugae is superior to the conventional denture.

Objective:The aim of this study was to evaluate the effects of two different disinfectant solutions’ immersion on the dimensional accuracy of different complete edentulous impressions.Materials and Methods:A specific custom-made metallic cast template was constructed and used for making both 120 alginate and zinc oxide eugenol (ZOE) paste impressions (60 for each). Disinfectants with 1% sodium hypochlorite and 2% glutaraldehyde were used for 10 and 60 min immersion of both impressions. After immersion time, the impressions were used for constructing 120 completely edentulous master stone models and divided into different groups according to the study. An electronic caliper was used for dimensional accuracy measurements of the casts. The data were collected and statistically analyzed according to the independent paired sample t-test at statistically significant level P < 0 05. One-way ANOVA test was used to compare between significant different groups.Results:There is no statistically significant difference in dimensional accuracy of alginate and ZOE paste impressions as disinfection with 1% sodium hypochlorite and 2% glutaraldehyde for 10 min and ZOE paste impressions for 60 min, where there is statistically significant difference in alginate impressions dimensional accuracy as disinfection with 1% sodium hypochlorite and 2% glutaraldehyde for 60 min.Conclusions:Possibility of ZOE impressions paste disinfected with 1% sodium hypochlorite and 2% glutaraldehyde for 10 or 60 min, not affecting on dimensional stability, while alginate impressions, only 10 min immersion in disinfectant not affecting the dimensional stability.

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