Comparison of mechanical properties and color stability of various vacuum-formed orthodontic retainers: An in vitro study

Background: Vacuum-formed retainer (VFR) is the most used retainer due to its higher aesthetic properties and lower cost, their mechanical properties of are important in determining the stability and long-term use of appliances made out of them. Aim: This study aimed to evaluate and compare the flexural modulus, surface hardness, and color stability of three different VFR materials. Methods: Three different VFR materials, namely Duran, Keystone, and Zendura, of 1 mm thickness, were tested after thermoforming for flexural modulus, hardness, and color stability. They were formed over a stainless-steel model of 12 mm diameter and 6 mm height. Results: There were significant statistical differences (p = 0.000) in the flexural modulus and hardness of the three materials. Regarding color stability, Zendura exhibited significantly higher ΔE* values than Keystone and Duran (p < 0.05). Conclusions: Zendura had the highest flexural modulus and hardness compared with Duran and Keystone; however, it is more susceptible to color change compared to the other tested materials

Adoption of new endodontic technology by dental practitioners in Saudi Arabia

AbstractThe purpose of this study was to assess the adoption of new endodontic technology by a population of endodontists (ENs) and general dental practitioners (GPs) practicing in Riyadh, Saudi Arabia. A total of 250 self-administered questionnaires were distributed to 50 randomly selected private dental clinics. The questionnaire consisted of questions regarding the use of NiTi rotary instruments, Digital radiography, and Electronic Apex Locators. Follow-up questions investigated the reason for not using the specified technology by selecting one or more of the stated choices. In addition, the type of rotary NiTi instrument system and the type of apex locator used were explored. The response rate was 56.4%; 121 GPs and 20 EN participated in the study. The percentage of dentists (GPs+ENs) who used NiTi rotary instruments was 46.1%, Digital radiography was 40.7%, and Electronic Apex Locators was 48.9%. The percentage of ENs who used the three technologies was higher than that of GPs, the difference was statistically significant (P=0.001). The most common reason for not using the three new technologies was the lack of availability. In addition to unavailability, NiTi rotary instruments and Electronic Apex Locators were not used because of lack of training and concern about instrument fracture (rotary NiTi) and patient safety (Electronic Apex Locators). The fact that more than 50% of dentists (GPs+ENs) practicing in Saudi Arabia have never used rotary NiTi instrumentation systems, Digital radiography, or Electronic Apex Locators underlines the importance of supporting increased utilization of new endodontic technologies by providing professional training opportunities for current and future dentists

Water Sorption, Water Solubility, and Rheological Properties of Resin-Based Dental Composites Incorporating Immobilizable Eugenol-Derivative Monomer

The present study aimed to evaluate the properties of new dental formulations incorporating a new polymerizable-derivative of eugenol (EgGMA). The experimental composites were prepared (by weight) with 35% resin-based matrix (1:1, bisphenol A-glycidyl methacrylate/triethylene glycol dimethacrylate) and 65% reinforcing materials (4:3, hydroxyapatite/zirconium oxide). A portion of 0.0, 2.5, and 5.0% of the resins with respect to the total composite was replaced by EgGMA monomer to obtain TBEg0, TBEg2.5, and TBEg5, respectively. The complex viscosity (at 25 and 37 &deg;C), degree of conversion (DC), and water sorption (WSP) and water solubility (WSL) (3 cycles of sorption-desorption process) were investigated. Data were statistically analyzed using one-way and Tukey post-hoc tests. The results revealed a viscosity reduction with shear-thinning behavior as the EgGMA amount and temperature increased. The average complex viscosities at a lower frequency (&omega; = 1.0 rad/s) and at 25 &deg;C were 234.7 &plusmn; 13.4, 86.4 &plusmn; 16.5, and 57.3 &plusmn; 17.1 (kPa&middot;s) for TBEg0, TBEg2.5, and TBEg5, respectively. The inclusion of EgGMA led to a lower DC and WSP but higher WSL, compared to those of the reference (TBEg0). However, no significant differences between TBEg2.5 and control were detected (p &gt; 0.05). Therefore, the incorporation of EgGMA in a low quantity, e.g., up to 8.45 mol% of resins, within the matrix may enhance the composite&rsquo;s performance, including handling and solubility properties without any apparent effect on DC and water sorption, making it a promising monomeric biomaterial for various applications including restorative dentistry