New zirconia compositions with optimized esthetic properties have emerged due to the fast-growing technology in zirconia manufacturing. However, the large variety of commercial products and synthesis ...routes, make impossible to include all of them under the general term of “monolithic zirconia ceramics”. Ultra- or high translucent monolithic formulations contain 3–8mol% yttria, which results in materials with completely different structure, optical and mechanical properties. The purpose of this study was to provide an update to the current knowledge concerning monolithic zirconia and to review factors related to strength and aging resistance. Factors such as composition, coloring procedures, sintering method and temperature, may affect both strength and aging resistance to a more or less extend. A significant reduction of mechanical properties has been correlated to high translucent zirconia formualtions while regarding aging resistance, the findings are contradictory, necessitating more and thorough investigation. Despite the obvious advantages of contemporary monolithic zirconia ceramics, further scientific evidence is required that will eventually lead to the appropriate laboratory and clinical guidelines for their use. Until then, a safe suggestion should be to utilize high-strength partially-stabilized zirconia for posterior or long span restorations and fully-stabilized ultra-translucent zirconia for anterior single crowns and short span fixed partial dentures.
This study evaluated roughness parameters and phase transformation of monolithic zirconia ceramics after various mechanical and laser thermal treatments. Fully sintered monolithic zirconia cylinder ...specimens were divided to five groups, according to the applied surface treatment: CL: control, GB: grit-blasted with glass particles. AL50: grit-blasted with 50 μm alumina particles, AL90: grit-blasted with 90 μm dyed-alumina particles and FEML: subjected to femto laser thermal treatment. Six roughness parameters (Sa, Sq, Sz, Sci, Svi and Sdr) were measured by optical profilometry. Phase transformation in zirconia was determined by micro-Raman spectroscopy. The highest roughness values were recorded in AL90 and FEML groups, followed by AL50. AL90 presented statistically higher monoclinic phase content compared to all other groups. Control and GB groups presented similar roughness without phase transformation. Laser thermal treatment causes minimal destruction of the zirconia surface, and can be suggested as an alternative to other roughening treratments, for enhancing the adhesive potential to dentin.
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Periodontal diseases like periodontitis and peri-implantitis have been linked with Gram-negative anaerobes. The incorporation of various chemotherapeutic agents, including metal ions, ...into several materials and devices has been extensively studied against periodontal bacteria, and materials doped with metal ions have been proposed for the treatment of periodontal and peri-implant diseases. The aim of this review is to discuss the effectiveness of materials doped with metal and metalloid ions already used in the treatment of periodontal diseases, as well as the potential use of alternative materials that are currently available for other applications but have been proved to be cytotoxic to the specific periodontal pathogens. The sources of this review included English articles using Google Scholar™, ScienceDirect, Scopus and PubMed. Search terms included the combinations of the descriptors “disease”, “ionic species” and “bacterium”. Articles that discuss the biocidal properties of materials doped with metal and metalloid ions against the specific periodontal bacteria were included. The articles were independently extracted by two authors using predefined data fields. The evaluation of resources was based on the quality of the content and the relevance to the topic, which was evaluated by the ionic species and the bacteria used in the study, while the final application was not considered as relevant. The present review summarizes the extensive previous and current research efforts concerning the use of metal ions in periodontal diseases therapy, while it points out the challenges and opportunities lying ahead.
The purpose of this paper was to update the knowledge concerning the wear, translucency, as well as clinical performance of monolithic zirconia ceramics, aiming at highlighting their advantages and ...weaknesses through data presented in recent literature. New ultra-translucent and multicolor monolithic zirconia ceramics present considerably improved aesthetics and translucency, which, according to the literature reviewed, is similar to those of the more translucent lithium disilicate ceramics. A profound advantage is their high strength at thin geometries preserving their mechanical integrity. Based on the reviewed articles, monolithic zirconia ceramics cause minimal wear of antagonists, especially if appropriately polished, although no evidence still exists regarding the ultra-translucent compositions. Concerning the survival of monolithic zirconia restorations, the present review demonstrates the findings of the existing short-term studies, which reveal promising results after evaluating their performance for up to 5 or 7 years. Although a significant increase in translucency has been achieved, new translucent monolithic zirconia ceramics have to be further evaluated both in vitro and in vivo for their long-term potential to preserve their outstanding properties. Due to limited studies evaluating the wear properties of ultra-translucent material, no sound conclusions can be made, whereas well-designed clinical studies are urgently needed to enlighten issues of prognosis and long-term survival.
Different approaches to develop engineered scaffolds for periodontal tissues regeneration have been proposed. In this review, innovations in stem cell technology and scaffolds engineering focused ...primarily on Periodontal Ligament (PDL) regeneration are discussed and analyzed based on results from pre-clinical in vivo studies and clinical trials. Most of those developments include the use of polymeric materials with different patterning and surface nanotopography and printing of complex and sophisticated multiphasic composite scaffolds with different compartments to accomodate for the different periodontal tissues' architecture. Despite the increased effort in producing these scaffolds and their undoubtable efficiency to guide and support tissue regeneration, appropriate source of cells is also needed to provide new tissue formation and various biological and mechanochemical cues from the Extraccellular Matrix (ECM) to provide biophysical stimuli for cell growth and differentiation. Cell sheet engineering is a novel promising technique that allows obtaining cells in a sheet format while preserving ECM components. The right combination of those factors has not been discovered yet and efforts are still needed to ameliorate regenerative outcomes towards the functional organisation of the developed tissues.
Purpose
Recent modifications in composition, structure, and fabrication methods have led to monolithic zirconia ceramics of superior translucency. However, during aging, intrinsic microstructural ...features, such as grain boundaries and pores, may affect light scattering and consequently the translucency of zirconia. The aim of this study was to systematically review if hydrothermal aging affects the translucency of monolithic zirconia.
Materials and Methods
An electronic search in Medline and Scopus was conducted to identify the effect of hydrothermal aging on the translucency of zirconia. The search was limited to English‐language publications and in vitro studies. The following search terms were used alone or in combination: “monolithic zirconia,” “full contour zirconia,” “Y‐TZP zirconia,” “tetragonal zirconia,” “cubic zirconia,” “aging,” “hydrothermal aging,” “steam autoclave,” “translucency,” “translucency parameter,” and “contrast ratio.” From the titles found after searching the electronic databases, only 10 articles met the inclusion criteria and were included in this review. The translucency parameter or total transmittance was used to extract data from the studies.
Results
Aging reduced the translucency of monolithic zirconia in most of the studies; however, the differences varied according to the brand tested and the microstructure and thickness of the specimens. The thinner specimens presented higher translucency alterations. Although in all studies a change in translucency was recorded, its mean values suggest that the differences are within the acceptability threshold in most cases, independent of the color system used to calculate translucent parameter, so they are clinically undetectable. For longer aging times, beyond the perspective clinical life of the restorations, the change in translucency is higher than the acceptability threshold.
Conclusions
There is a controversy regarding how aging affects the translucency of monolithic zirconia ceramics; however, this may not be clinically important, as in most cases, changes (either decrease or increase) in translucency were within the acceptability thresholds.
In a century when environmental pollution is a major issue, polymers issued from bio-based monomers have gained important interest, as they are expected to be environment-friendly, and biocompatible, ...with non-toxic degradation products. In parallel, hyperbranched polymers have emerged as an easily accessible alternative to dendrimers with numerous potential applications. Glycerol (Gly) is a natural, low-cost, trifunctional monomer, with a production expected to grow significantly, and thus an excellent candidate for the synthesis of hyperbranched polyesters for pharmaceutical and biomedical applications. In the present article, we review the synthesis, properties, and applications of glycerol polyesters of aliphatic dicarboxylic acids (from succinic to sebacic acids) as well as the copolymers of glycerol or hyperbranched polyglycerol with poly(lactic acid) and poly(ε-caprolactone). Emphasis was given to summarize the synthetic procedures (monomer molar ratio, used catalysts, temperatures, etc.,) and their effect on the molecular weight, solubility, and thermal and mechanical properties of the prepared hyperbranched polymers. Their applications in pharmaceutical technology as drug carries and in biomedical applications focusing on regenerative medicine are highlighted.
The effect of thermal aging on the color stability of monolithic zirconia has not been thoroughly investigated.
The purpose of this in vitro study was to evaluate the color stability before and after ...thermocycling of monolithic zirconia specimens, which were either preshaded or characterized in the laboratory through the assessment of color parameters L*, a*, and b*.
A total of 80 specimens (10×10×15 mm) were prepared from zirconia disks (BruxZir) and divided into 2 groups. The first group consisted of preshaded specimens from disks 100, 200, 300, and 400, and the second group consisted of white specimens characterized before the sintering stage with coloring liquids in shades A2, B2, C2, and D2. Ten specimens of each shade were used. A double-beam ultraviolet-visible light recording spectrophotometer was used to assess the color parameters L*, a*, and b* before and after thermocycling. The color difference ΔE was calculated based on ΔΕ=(ΔL*)2+(Δa*)2+(Δb*)2½. The reliability of the examiner was investigated by MedCalc v12.5 software, and the tests of normality, homogeneity of variances, and 1-way ANOVA statistical analysis of variance were performed by IBM Statistics SPSS v20.0 software (α=.05).
No statistically significant ΔΕ (P>.05) was observed among the different groups after thermocycling. All ΔΕ values were below the limit of the 3.7 that an untrained observer can perceive. Only for the specimens in shades 200 and 400 was ΔΕ above 1, revealing a visible color difference, which, however, was still clinically acceptable. The L*, a*, and b* values for both liquid-shaded and preshaded zirconia specimens were not significantly affected by thermocycling. A higher color stability for laboratory-characterized compared with preshaded monolithic zirconia was observed irrespective of the color shade.
Within the limitations of this in vitro study, monolithic zirconia specimens of any shade, either preshaded or characterized in the laboratory, can be considered as color-stable materials after thermocycling.
The present study systematically reviewed the literature regarding the bond strength durability of zirconia ceramics to resin-based luting cements after application of different bonding protocols and ...aging conditions. Electronic searches in PubMed, Scopus, and Web of Science databases were performed for relevant literature published between January 1st 2015 and November 15th 2022. Ninety-three (93) English language in-vitro studies were included. The percentage of the mean bond strength change was recorded prior to and after artificial aging, and the weighted mean values and 95% confidence intervals were calculated. Bonding protocols were classified based on the combination of MDP/non-MDP containing cement/primer and surface pretreatment, as well as the level of artificial aging performed. Alumina sandblasting (SA) was identified as the most frequently used surface pre-treatment while an insufficient number of studies was identified for each category of alternative surface treatments. The combination of MDP cement with tribochemical silica coating (TSC) or SA yielded more durable results after aging, while the application of SA and TSC improved bond durability when a non-MDP cement and a non-MDP primer were used. TSC may lead to increased bond durability compared to SA, whereas MDP cements may act similarly when combined with SA or TSC.
One type of failure in complete or partial dentures is the detachment of resin teeth from denture base resin (DBR). This common complication is also observed in the new generation of digitally ...fabricated dentures. The purpose of this review was to provide an update on the adhesion of artificial teeth to denture resin substrates fabricated by conventional and digital methods.
A search strategy was applied to retrieve relevant studies in PubMed and Scopus.
Chemical (monomers, ethyl acetone, conditioning liquids, adhesive agents, etc.) and mechanical (grinding, laser, sandblasting, etc.) treatments are commonly used by technicians to improve denture teeth retention with controversial benefits. Better performance in conventional dentures is realized for certain combinations of DBR materials and denture teeth after mechanical or chemical treatment.
The incompatibility of certain materials and lack of copolymerization are the main reasons for failure. Due to the emerging field of new techniques for denture fabrication, different materials have been developed, and further research is needed to elaborate the best combination of teeth and DBRs. Lower bond strength and suboptimal failure modes have been related to 3D-printed combinations of teeth and DBRs, while milled and conventional combinations seem to be a safer choice until further improvements in printing technologies are developed.
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