Accuracy of Intraoral Scanners for Recording the Denture Bearing Areas: A Systematic Review

PURPOSE: To systematically review clinical and laboratory studies that investigated the accuracy of intraoral scanners in recording denture bearing areas. MATERIALS AND METHODS: Electronic and manual searches were conducted to identify all the available clinical and laboratory studies reporting the accuracy of digital impressions for recording denture related soft tissues. After the application of predetermined inclusion and exclusion criteria, the final list of articles was reviewed to meet the objective of this study. RESULTS: The inclusion criteria were met by 18 studies out of which 8 were clinical and the rest were laboratory investigations. The eligible studies assessed the accuracy of intraoral scanners in recording both the denture supporting structures and the peripheral mobile tissues. The accuracy results were different among the various intraoral scanners. Likewise, the effect of several influencing factors, such as artificial markers, scanner head size, scanning strategy, and the operator's experience, were evaluated. CONCLUSION: While the accuracy of intraoral scanners was comparable to the conventional techniques in recording bony structures with attached mucosa, they were not capable of accurately registering the mobile tissues. In addition, factors such as presence of a marker, larger scanner head size and specific scanning techniques appeared to improve the accuracy of the digital impression. This article is protected by copyright. All rights reserved

Deposition of Crystalline Hydroxyapatite Nanoparticles on Y-TZP Ceramic: A Potential Solution to Enhance Bonding Characteristics of Y-TZP Ceramics

Objectives: Many advantages have been attributed to dental zirconia ceramics in terms of mechanical and physical properties; however, the bonding ability of this material to dental structure and/or veneering ceramics has always been a matter of concern. On the other hand, hydroxyapatite (HA) shows excellent biocompatibility and good bonding ability to tooth structure, with mechanically unstable and brittle characteristics, that make it clinically unacceptable for use in high stress bearing areas. The main purpose of this study was to introduce two simple yet practical methods to deposit the crystalline HA nanoparticles on zirconia ceramics. Materials and Methods: zirconia blocks were treated with HA via two different deposition methods namely thermal coating and air abrasion. Specimens were analyzed by scanning electron microscopy, energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). Results: In both groups, the deposition techniques used were successfully accomplished, while the substrate showed no structural change. However, thermal coating group showed a uniform deposition of crystalline HA but in air abrasion method, there were dispersed thin islands of HA. Conclusions: Thermal coating method has the potential to significantly alter the surface characteristics of zirconia. The simple yet practical nature of the proposed method may be able to shift the bonding paradigm of dental zirconia ceramics. This latter subject needs to be addressed in future investigations

Nanotechnology and Plant Extracts as a Future Control Strategy for Meat and Milk Products

Plant extracts, well known for their antibacterial and antioxidant activity, have potential to be widely used preservatives in the food industry as natural alternatives to numerous synthetic additives which have adverse impacts on health and the environment. Most plant compounds and extracts are generally recognized as safe (GRAS). The use of preservatives is of great importance for perishable foods such as meat and milk, which, along with their products, are commonly consumed food items globally. However, the bioavailability of plant compounds could be diminished by their interaction with food components, processing, and storage. Nanoencapsulation of plant extracts, especially essential oils, is an effective method for their application in food model systems. This technique increases the bioactivity of plant compounds by increasing their physical stability and reducing their size, without negative effects on organoleptic properties. Furthermore, a recent study showed that plant extracts act as good bioreductants for biosynthesis of nanoparticles. This so-called green synthesis method using plant extracts is a rapid, relatively inexpensive, safe, and efficient method for synthesis of nanoparticles including silver, gold, iron, lead, copper, cobalt, palladium, platinum, zinc, zinc oxide, titanium oxide, magnetite, and nickel. Some of these nanoparticles have antimicrobial potential which is why they are of great interest to the food industry. In this chapter, the nanoencapsulation of plant extracts and plant extract-mediated synthesis of nanoparticles and their potential application in order to improve the safety and quality and prolong the shelf life of meat and milk products are reviewed and discussed