One of the most widely used materials for the fabrication of prosthetic dental parts is acrylic resin. Its reasonable mechanical and physical properties make it a popular material for a wide range of dental applications. Recently, many attempts have been made to improve the mechanical and biological properties of this material, such as by adding fibres, nanoparticles, and nanotubes. The current study aimed to evaluate the effects of adding an antimicrobial agent, Ag-Zn zeolite, on the surface roughness and hardness of the denture base resins. Ag-Zn zeolite particles were chemically prepared and added at different concentrations (0.50 wt.% and 0.75 wt.%) to the heat cure (HC) and cold cure (CC) acrylic resins. Zeolite particles were characterized and confirmed using X-ray diffraction (XRD) and Energy-Dispersive X-ray Spectroscopy (EDX) attached with a Scanning Electron Microscope (SEM). Sixty disk shape specimens (40 mm diameter and 2 mm thickness) were fabricated from the HC and CC resins with and without the zeolite. All the specimens were divided into two main groups based on the acrylic resins, then each was subdivided into three groups (n = 10) according to the concentration of the Ag-Zn zeolite. A surface roughness and a hardness tester were used to measure the surface finish and hardness of the specimens. The analysed data showed that the surface roughness values significantly decreased when 0.50 wt.% and 0.75 wt.% zeolite were incorporated in the HC resin specimens compared to the control group. However, this reduction was not significant in the case of CC resin, while the surface hardness was significantly improved after incorporating 0.50 wt.% and 0.75 wt.% zeolite for both the CC and HC resins. Incorporating Ag-Zn zeolite with acrylic resin materials could be beneficial for improving their surface finish and resistance to surface damage as defined by the higher hardness.

Background:The accuracy of surface production details in the dental models determines the success of the dental prosthesis in clinical application. Aim: This in vitro study aims to compare between dental stone models produced using two types of techniques for pouring the addition silicone impression. Method: The control group was poured using the conventional vibration technique at a vibration frequency of 3000 cycles/min and the experimental group was poured by an ultrasound vibration technique at a frequency of 28 kHz in order to assess the difference in pouring techniques in terms of reproduction of details and surface hardness. A stainless steel die, prepared based on the ISO 6873, was employed to fabricate samples for evaluating the surface details. Fisher's exact test scoring scale was employed to qualititatively assess the reproduced surface details. Vickers hardness was measured to evaluate the surface hardness of cylindrical stone samples poured by the two different techniques. Results:The results indicated that the reproduction of details of the stone samples poured by the ultrasound vibration technique were not significantly different (P > 0.05) in comparison with that poured by the conventional vibration technique. However, the surface hardness was significantly enhanced (P = 0.04) by the ultrasound vibration pouring technique. Conclusion: Although the application of ultrasound vibration during dental cast fabrication did not provide any significant clinical advantages in terms of surface reproducibility, it could significantly improve the surface hardness compared with the traditional vibration technique.