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Most dental works require a diagnostic impression; alginate is contemplated as the most popular material used for this purpose. Titanium dioxide nanoparticles show evidence of antimicrobial activity in the recent era, for this purpose, this study aimed to evaluate the effect of adding Titanium dioxide nanoparticles on antimicrobial activity and surface detail reproduction of alginate impression material. Materials and methods: Titanium dioxide nanoparticles (purity = 99%, size= 20nm) was added to alginate at three different concentrations (2%, 3% and 5%). 84 samples were prepared in total. Samples were tested for antimicrobial activity using a disc diffusion test, and surface detail reproduction was done using (ISO 21563:2021). One-way ANOVA and independent sample t-test were used for data analysis through SPSS software. Results: for the antimicrobial test, inhibition zones for Streptococcus mutans and Candida albicans showed significant changes concerning the alteration in Titanium dioxide nanoparticle concentrations. The inhibition zone significantly increased with an increase in the percentage of Titanium dioxide nanoparticles. The mean of the inhibition zone for S. mutans was superior to C. albicans and the difference was statistically significant. Regarding surface detail reproduction, the control group, 2% and 3% groups manifested very similar results, only the group to which 5% of Titanium dioxide nanoparticles were added showed a decline in detail reproduction when compared to the other three groups. Conclusion: Within the limitation of this study, we can conclude that the antimicrobial activity against S mutans and C. albicans were significantly increased in modified groups, and this escalation was directly linked to the increase in Titanium dioxide nanoparticles concentration. In contrast, the surface detail reproduction was decreased when adding 5% Titanium dioxide nanoparticles to alginate.

Assessment of retention characteristics of different attachments following new modifications (an in vitro study)Background and objectives: This study aimed to compare the retention characteristics of different attachments used to retain partial dentures following new modifications. Methods: In this study three types of commonly used extracoronal castable attachments were selected, namely (1) Preci-verttix standard, CEKA attachment, (2) Preci-sagix mini size, CEKA attachment, (3) OT-cap normal, Rhein 83. They underwent simple modifications in order to improve their retention. A total of forty-two samples were prepared in three main groups. Each group subdivided into two subgroups with fourteen samples; 7 samples for non-modified and 7 for modified attachments. The tensile force was applied using a universal testing machine at a cross-head speed of 50 mm/min and maximum retention force at dislodgment was recorded. Strain and stress at dislodgement were calculated. Data were collected and analyzed using one-way ANOVA followed by Duncan test and finally paired ttest was performed for comparing the modified and non-modified attachments.Results: For all attachments, retention was increased significantly following modification except for OT-cap, which showed a non-significant reduction in retention. Modified Precivertix attachment was most retentive with the mean value of (48.893) Newton. For all attachments strain at dislodgement was increased after modification and highest mean value of (1.292) was recorded for Preci-sagix. Stress at dislodgement was increased following modification for all attachments, except Preci-vertix which showed significant reduction of stress. Conclusions: Modified Preci-vertix attachment showed the highest retention value with a significant reduction in stress.

Objective: This study aimed to evaluate the effect of adding titanium dioxide nanoparticles (TiO2NPs) on Shore A hardness, Young’s modulus, and tear strength of alginate impression material. Methods: Each test consists of one control group (alginate without TiO2NPs), and three test groups (2%, 3%, and 5%) of TiO2NPs were added, respectively. For each group, seven samples were constructed. For Shore A hardness, the samples were prepared according to ISO standards (7619-1:2010); Young’s modulus was calculated from the obtained Shore A hardness value according to a special standard equation. In contrast, for tear strength, the samples were prepared according to ASTM D 624-00. Results: The Control group exhibited a significantly less Shore A hardness value than all the other groups except the group that contained 2% TiO2NPs, where the increase in the hardness value was non-significant. A similar result was observed for Young’s modulus test, where the addition of TiO2NPs significantly increased Young’s modulus compared to the control group. Although, on the contrary, the tear strength was significantly improved by adding 3% TiO2NPs compared to control and other groups, there was a significant drop in the value of tear strength when 5% TiO2NPs were added to alginate. Conclusions: The addition of 3% TiO2NPs to dental alginate increased Shore A hardness, Young’s modulus, and significantly improved tear strength.