Objective: Nanotechnology has progressed significantly and particles as small as 3 nm are being employed in resin-based restorative materials to improve clinical performance. The goal of this review is to report the progress of nanotechnology in Restorative Dentistry by reviewing the advantages, limitations, and applications of resin-based restorative materials with nanoparticles.Materials and Methods: A literature review was conducted using PubMed/ Medline, Scopus and Embase databases. In vitro, in vivo and in situ research studies published in English between 1999 and 2020, and which focused on the analysis of resin-based restorative materials containing nanoparticles were included.Results: A total of 140 studies were included in this review. Studies reported the effect of incorporating different types of nanoparticles on adhesive systems or resin composites. Mechanical, physical, and anti-bacterial properties were described. The clinical performance of resin-based restorative materials with nanoparticles was also reported. Conclusions:The high surface area of nanoparticles exponentially increases the bioactivity of materials using bioactive nanofillers. However, the tendency of nanoparticles to agglomerate, the chemical instability of the developed materials and the decline of rheological properties when high ratios of nanoparticles are employed are some of the obstacles to overcome in the near future. Clinical significance: In spite of the recent advancements of nanotechnology in resin-based restorative materials, some challenges need to be overcome before new nano-based restorative materials are considered permanent solutions to clinical problems. K E Y W O R D S dental adhesives, nanohybrid, nanoparticles, resin composite | INTRODUCTIONNanotechnology, also known as molecular technology or molecular engineering, consists of the steps involved in processing, separating, consolidating, and deforming materials by one atom or molecule 1 to generate structures in the size range of 0.1-100 nanometers. 2 The inorganic fillers employed in dental materials may be categorized according to their size range, varying from macrofillers to nanofillers, and their size is controlled either by a top-down or a bottom-up manufacturing approach. Figure 1 summarizes the historical
<p><strong> </strong>This case report illustrates a conservative technique for reintervention on anterior composite restorations in a young patient with composite veneers. The treatment incorporated the use of photos and digital planning to establish a harmonious smile design. In order to conserve the dental tissues, existing resin composites restorations in maxillary anterior teeth were carefully removed to minimize enamel reduction, followed by a study of color and shade of teeth considering factors such as hue, chroma, luminosity, opacity, translucency and light effects. Eight direct veneers were built up with resin composite taking the optical properties of the material into account and their influence on the thickness of the layers that create specific light effects when superimposed on each other. To obtain excellent results with a predictable working protocol, nanohybrid composite systems facilitate good aesthetics, avoiding more invasive treatment in an economic manner.</p><p><strong>Keywords</strong></p><p>Dental aesthetic; Optical proprieties; Resin composite.</p>
ObjectiveThis study aimed to evaluate the color stability (ΔE00) of bis‐acryl resins after different immersion solutions and storage time by different evaluation methods.Materials and methodsSixty specimens (n = 30) were prepared from Protemp 4 and Structur 3. The specimens were divided into three groups (n = 10), according to the immersion solution (artificial saliva, cola beverage, and yerba mate tea) and evaluated at two storage times (7 and 14 days). The ΔE00 of each group was calculated using color coordinates obtained by a spectrophotometer and by a digital method, using the CIEDE2000 color difference formula. Data were analyzed by three‐way ANOVA and Tukey test (α = 0.05).ResultsThe 7‐day period presented the lowest ΔE00 values, regardless of the material and solution evaluated for both evaluation methods (ΔE00 < 0.93; ΔE00 < 3.12). The immersion solution with the highest color change was yerba mate tea after 14 days (ΔE00 > 2.11). For digital analyses, all materials and solutions at both times presented ΔE00 values higher than the clinically acceptable (ΔE00 > 1.8), while in spectrophotometer only in yerba mate tea (14 days) Structur was above the clinical acceptability level.ConclusionsYerba mate tea was the immersion solution with a higher color change in both materials and assessment methods. The highest values were found after 14 days of immersion, regardless of the solution. The ΔE00 for the digital method was higher than the spectrophotometer analysis.Clinical significanceIt is important to identify the influence of staining beverages on interim materials used in patients requiring temporary rehabilitation. The use of a spectrophotometer seems to be more accurate than the digital method for the evaluation of color parameters of the tested materials.
Objective This study aims to evaluate the effect of sonochemical treatment on the surface of yttria-stabilized tetragonal zirconia (Y-TZP) before and after the final sintering. Material and Methods Twenty-eight Y-TZP discs were divided into four groups (n=7), according to surface treatment: PRE: pre-sintering sonication with 30% nominal power for 15 min; POS: post-sintering sonication with 30% nominal power for 15 min; JAT: air abrasion with 50-μm alumina particles; and CON: control group with no treatment. The POS and JAT groups were sintered before sonication and the PRE group after sonication. Surface roughness was analyzed using confocal microscopy, after which resin cement cylinders were placed on the surface of the Y-TZP discs and subjected to mechanical microshear bond strength test until fracture. Surface roughness and microshear bond strength values underwent ANOVA and the Tukey tests. Results The surface roughness values for the PRE group (299.91 nm) and the POS group (291.23 nm) were not significantly different (p≥0.05), statistically, and the surface roughness value of the JAT group (925.21 nm) was higher than those of PRE and POS (p=0.007) groups. The mechanical microshear bond strength test showed that there was no statistically significant difference between the groups (p=0.08). Conclusions Therefore, the results showed that sonochemical treatment modifies the Y-TZP surface and is similar to the well-established sandblasting surface treatment regarding the strength of the bond with the resin cement.
Aim: The aim of this meta analysis was to evaluate the influence of the processing method on the marginal and internal gaps of lithium disilicate inlays/onlays. Settings and Design: A systematic literature review was conducted using the PubMed/Medline, Embase, Scopus, and Cochrane Library databases. This review was registered on the PROSPERO platform. Materials and Methods: The studies were selected according to the marginal and internal gaps of two different fabrication methods for lithium disilicate (milled and pressed). Statistical Analysis Used: The meta analysis was performed based on the Mantel–Haenszel and inverse variance methods, using the random effects model and a 95% confidence interval. Results: From all databases, 127 studies were identified. Four in vitro studies were included in the qualitative analysis and three in the meta analysis. Moreover, 197 restorations were evaluated (103 pressed and 94 milled). During the evaluation of only the internal gap, there was a statistically significant difference favoring the pressed technique ( P = 0.002). There was no statistically significant difference in the analyses of the marginal gap ( P = 0.530) and the total gap ( P = 0.450). Conclusion: Both the techniques provided acceptable marginal and total gaps, although the pressed technique revealed a more favorable internal adaptation than the milled onlays/inlays.
Yttria tetragonal zirconia polycrystal in the form of presintered commercial blocks is used to manufacture dental prostheses through computer-aided design/computer-aided manufacturing technology. Although it presents appropriate mechanical properties, it may fail because of defects resulting from the forming, presintering, machining, or sintering processes. The aim of the current study is to evaluate the influence of the presintering process on the microhardness of presintered blocks and on the elastic modulus of sintered materials. Blocks were formed by means of uniaxial and isostatic pressing. Next, they were presintered at different temperatures and soaking times, besides being subjected to the Vickers microhardness and mechanical tests to evaluate their elastic modulus. Statistical analyses showed that the presintering time at 900°C had no effect on microhardness, although it was significant at 950°C. The postsintering elastic modulus ranged from 205.7 to 231.9 GPa, which is similar to the range recorded in the literature. The presintering process had no influence on the postsintering mechanical resistance results.
Objective The bleaching agents may interact with restorative materials, such as dental amalgam, providing an increase mercury ions (Hg) release, whose toxic effect is known. Whereas many patients have amalgam restorations (AR) and seek bleaching treatments, the present study aimed to evaluate in vitro the amount of Hg released from AR made with spherical alloy, after being subjected to different concentrations of carbamide peroxide (CP) for home bleaching. Methods 40 class I AR were prepared in bovine teeth. Afterthe restoration, the samples were randomly allocated into 4 groups (n = 10): C (control group), CP10 (CP 10%) CP15 (CP 15%) CP20 (CP 20%) and its treatments were simulated for 14 days for 6 hours daily. The Hg ions released was measured by energy dispersive X-ray spectroscopy (EDS) and surface changes were assessed in the Scanning Electron Microscope (SEM). Hg levels (percent mass) were recorded and the differences were statistically analyzed using the Kruskal-Wallis test and Dunn’s “Post hoc” test. Results Statisticalanalysis showed the bleaching treatment resulted in a higher Hg release (p <0.05), although no visible changes were identified in micrographs when comparing the control group with the other groups (CP10, CP15, CP20). Conclusion Increased Hg release may be observed during simulated home bleaching.
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