COVID-19 and Alzheimer's Disease: A Literature Review.

There are a number of potential implications for the field of Alzheimer's disease (AD) stemming from the global spread of "SARS-COV-2". Many studies that were conducted by Cleveland Clinic researchers identified a link between COVID-19 infection and brain abnormalities seen in people with AD. This article explains the association between COVID-19 and AD and how people with AD are affected by COVID-19, whether directly or indirectly. First, this article begins by explaining AD and its types, then giving an overview about COVID-19, its symptoms and the associated complications. Then, direct and indirect consequences of COVID-19 on people experiencing AD are discussed briefly. Some management strategies are recommended at the end of this article in addition to a future perspective on this topic. This article concludes by summarizing the main points mentioned about the association between COVID-19 and AD.

Effect of Active Bonding Application after Selective Dentin Etching on the Immediate and Long-Term Bond Strength of Two Universal Adhesives to Dentin.

The objective was to evaluate the influence of active bonding applications (ABA) for different time intervals after selective dentin etching (SDE) for 3 s on the microtensile bond strength (µTBS) to dentin of two universal adhesive systems (UAs): one containing 2-hydroxyethyl methacrylate (HEMA) (Scotchbond Universal, SBU), and one that was HEMA-free (Prime&Bond Universal, PBU). Dentin bovine specimens were divided into four groups: self-etch as control (SE), SDE + ABA for 15 s (SDE15), SDE + ABA for 20 s (SDE20), and SDE + ABA for 25 s (SDE25). The µTBS test was performed after a water storage of 24 h and 6 months. Scanning electron microscopy (SEM) was used in order to examine the resin−dentin interface. For the PBU, the µTBS was significantly influenced only by the aging factor (p < 0.026). A statistically significant decrease in the µTBS after 6 months of aging was observed only for the SDE15 group. For SBU, µTBS was significantly influenced by the protocol application and the aging time (p ≤ 0.041). The groups SDE15, SDE20, and SDE25 achieved statistically significant higher values (after 24 h and 6 months). No considerable variances were noticed in the homogeneity and continuity of the hybrid layer (HL) among the groups. In conclusion, SDE and ABA improved the µTBS only of a HEMA-containing universal adhesive.

The fifth dimension in esthetic dentistry.

Every human smile is unique and special, reflecting the different shapes, textures, and colors of the teeth as well as their combinations. This uniqueness conveys a direct and specific message when it comes to creating a new smile design. Dentists need to consider the 'unity of the whole' concept in this task, which involves bringing together biology, structure, function, and esthetics to create the fifth dimension of the smile. This approach is quite different from the traditional one. A smile reflects the personality and emotional state of the patient, and the translation of this into a new smile design occurs in various ways. This can be performed either through analog methods or digitally; however, the use of visual language will assist the dentist and dental technician in the creation of a personalized smile design. Nowadays, with the significant digital advances that have occurred in dentistry, there are systems on the market that help the dental team to create a personalized new smile design for each specific patient. The Rebel system is one example of such a system. It is actually a virtual laboratory that creates individualized smile designs in three dimensions. The system, with its very sophisticated artificial intelligence (AI)-based software, immediately creates a digital wax-up (STL file). It is therefore simple to use for dentists and dental technicians at all skill levels because the direct mock-up and wax-up stages are eliminated.

Effect of Composite Core Materials on Fracture Resistance of Endodontically Treated Teeth: A Systematic Review and Meta-Analysis of In Vitro Studies.

Various material properties are involved in the success of endodontically treated restorations. At present, restorative composites are commonly employed as core build-up materials. This study aimed to systematically review the literature to assess the effect of using composite core materials on the in vitro fracture of endodontically treated teeth. Two different reviewers screened the literature, up to June 2021, in five distinct electronic databases: PubMed (MedLine), Scopus, Scielo, ISI Web of Science, and EMBASE. Only in vitro studies reporting the effect of the use of composite core materials on the fracture resistance of endodontically treated teeth were included. A meta-analysis was carried out using a software program (Review Manager v5.4.1; The Cochrane Collaboration, Copenhagen, Denmark). The risk of bias in each study was assessed following the parameters of another systematic review. A total of 5016 relevant papers were retrieved from all databases. After assessing the title and abstract, five publications remained for qualitative analysis. From these, only three studies remained for meta-analysis. The fracture strength of endodontically treated teeth where a core build-up composite was used was statistically significantly higher than the control (p = 0.04). Most of the analyses showed a high heterogenicity. The in vitro evidence suggests that the composite core build-up with higher filler content tended to improve the fracture resistance of the endodontically treated teeth, in comparison with conventional composite resins. This research received no external funding. Considering that this systematic review was only carried out on in vitro papers, registration was not performed. Furthermore, there were no identified clinical studies assessing core build-up materials; therefore, more well-designed research on these materials is needed.