Color in Business, Science, and Industry

Statement of problem With a number of zirconia ceramic materials currently available for clinical use, an overview of the scientific literature on the adhesion methods and their potential influence is indicated. Purpose The purpose of this systematic review was to classify and analyze the existing methods and materials proposed to improve adhesion to zirconia surfaces. Material and methods The current literature of in vitro studies examining the bond strength on zirconia ceramics, including clinical studies from 1998 until 2014, was analyzed. A search of the English language literature was undertaken using MEDLINE and PubMed, and a hand search was made for any relevant research paper from the library of a dental school. Papers evaluating only alumina restoration bond or ceramic-zirconia bond were excluded. Results A total of 134 publications were identified for analysis. Different adhesive techniques with different testing methods were reviewed. Results were difficult to compare in that the parameters varied in each research protocol. Conclusions Airborne-particle abrasion and tribochemical silica coating are reference pretreatment methods. Adhesive monomers are necessary for chemical bonding. Surface contamination and aging have negative effects on adhesion to zirconia. Many factors influence each combination of zirconia material, such as surface treatment, adhesive medium, and aging conditions. Laboratory studies should be confirmed by clinical trials.

http://www.unitau.br/files/arquivos/category_126/Tzanakakis_2016_1455555314.pdf

Is there a potential for durable adhesion to zirconia restorations? A systematic review

Statement of problem Yttria-stabilized tetragonal zirconia polycrystal has been used as a dental biomaterial for several decades because the fracture toughness and bend strength are increased by a stress-induced transformation-toughening mechanism. However, its esthetics are compromised by its poor translucency and grayish-white appearance. Purpose The purpose of the present systematic review was to assess information on the mechanical, chemical, and optical requirements of monolithic zirconia dental restorations. Material and methods The following databases (2010 to 2015) were electronically searched: ProQuest, EMBASE, SciFinder, MRS Online Proceedings Library, Medline, Compendex, and Journal of the American Ceramic Society. The search was limited to English-language publications, in vitro studies, experimental reports, and modeling studies. Results The data from 57 studies were considered in order to review the intrinsic and extrinsic characteristics of zirconia and their effects on the optical properties. Conclusions The materials and microstructural issues relevant to the esthetics and long-term stability of zirconia have been considered in terms of monolithic restorations, while there also are restorations specifically for esthetic applications. Although zirconia-toughened lithium silicate offers the best esthetic outcomes, transformation-toughened zirconia offers the best mechanical properties and long-term stability; cubic stabilized zirconia offers a potential compromise. The properties of these materials can be altered to some extent through the appropriate application of intrinsic (such as, annealing) and extrinsic (such as, shade-matching) parameters.

Optical properties of zirconia ceramics for esthetic dental restorations: A systematic review.

The aim of this study was to systematically review the literature to assess if low-temperature degradation (LTD) simulation in autoclave promotes deleterious impact on the mechanical properties and superficial characteristics of Y-TZP ceramics compared to the non-aged protocol. The MEDLINE via PubMed electronic database was searched with included peer-reviewed publications in English language and with no publication year limit. From 413 potentially eligible studies, 49 were selected for full-text analysis, 19 were included in the systematic review with 12 considered in the meta-analysis. Two reviewers independently selected the studies, extracted the data, and assessed the risk of bias. Statistical analysis was performed using RevMan 5.1, with random effects model, at a significance level of p 20h. However, for shorter aging times (≤20h), there was no difference between groups. Pressure subgroup analysis presented a statistical difference (p<0.05) only when a pressure ≥2bar was employed, favoring non-aging group. Temperature subgroup analysis showed a statistical difference (p<0.05) only when temperature=134°C was used, favoring the non-aging group. M-phase % content analysis presented statistical difference (p<0.05) when more than 50% of m-phase content was observed, favoring non-aging group. High heterogeneity was found in some comparisons. Aging in autoclave promoted low-temperature degradation, impacting deleteriously on mechanical properties of Y-TZP ceramics. However, the effect of LTD depends on some methodological parameters indicating that aging time higher than 20h; pressure ≥2bar and temperature of 134°C are ideal parameters to promote LTD effects, and that those effect are only observed when more than 50% m-phase content is observed.

Low-temperature degradation of Y-TZP ceramics: A systematic review and meta-analysis.

Optical properties and light irradiance of monolithic zirconia at variable thicknesses

https://cyberleninka.org/article/n/1339685.pdf

Micro-shear bond strength of different resin cements to ceramic/glass-polymer CAD-CAM block materials.

Aim The aim was to evaluate the influence of sandblasting with various propulsion pressures on the phase transformation, flexural strength and Weibull modulus of a yttria stabilized tetragonal zirconia polycrystalline ceramic (Y-TPZ). In addition, the susceptibility of cyclic loading and low-temperature degradation under two different conditions (chemical and thermal aging) was investigated. Materials and methods The specimens [105 bar-shaped specimens (19.3×14.5×1.3 mm 3 )] were equally divided into seven groups ( n =15) according to the test protocols. The specimens in control group received no surface treatment (Group A). Groups B1, B2 and B3 were airborne-particle abraded with 110 μm Al 2 O 3 particles at 200 kPa, 400 kPa and 600 kPa (2 bar, 4 bar and 6 bar) pressure, respectively. Group C was submitted to mechanical cyclic loading under 200 N 20,000 times sinusoidal loading/unloading at a frequency of 10 Hz between 10% and 100% load in distilled water at 37 °C. Group D was submitted to thermal degradation in an autoclave at 134 °C under additional 200 kPa pressure for 5 h. Group E was immersed in 4% acetic acid at 80±5 °C for 168 h as chemical degradation testing. Following each treatment protocols, the three-point flexure test was used to calculate the flexural strength. Additionally, X-ray diffraction analysis was used to estimate the relative amount of monoclinic phase. The reliability of strength was assessed through the Weibull distribution. Statistical analysis was conducted with one-way ANOVA and Tukey׳s pairwise multiple comparisons. The treated and fractured surfaces were observed with SEM. Results Statistical analysis revealed that there were significant differences among the flexural strength results of all tested groups ( F =4.510, p 0.05). Group B2 demonstrated the highest strength values, whereas Group E showed the lowest (625.86±123.57; 466.56±91.50, respectively). Weibull moduli of all tested groups were statistically significant and ranging from 4.3 to 8.3. A greater amount of monoclinic phase was determined in the specimens of D, E and B3 groups (25.43%, 20.89% and 19.71%, respectively). However, lower amount was observed in groups A, B1 and B2 (10.02%, 13.35% and 15.19%, respectively). Conclusions The present study suggested that flexural strength of zirconia was significantly decreased by chemical degradation. In addition, surface conditioning, cyclic fatigue and thermal, chemical degradation conditions significantly changed the structural reliability of the material's strength.

Factors affecting the mechanical behavior of Y-TZP.

Does artificial aging affect mechanical properties of CAD/CAM composite materials

Objective. The purpose of this study was to evaluate the effect of different resin cement thickness on the push-out bond strength of different posts (CAD/CAM zirconia post (ZR post)) and an individually formed glass fiber reinforced composite post (IPN post) prior to and after thermal cycling (TC). Methods. Post spaces with a height of 9 mm and a diameter of 1.5 mm were drilled in 80 mandibular premolar teeth. Two groups (n = 40) were formed according to the posts used (IPN posts or ZR posts). Then the specimens were randomly assigned into two sub-groups according to the post diameter: (1) 1.5 mm in diameter and (2) 1.2 mm in diameter (n = 20/per group). All posts were luted with a self-adhesive luting agent according to the manufacturer's instructions by using endo tips. Half of the samples (n = 10) were submitted to thermal cycling (5000 cycles, 5–55°C). Thereafter, four 2-mm thick horizontal sections were obtained and subjected to push-out test. Failure modes were assessed quantitatively and m...

Influence of cement thickness on the bond strength of tooth-colored posts to root dentin after thermal cycling

Objectives:
The aim of this study was to compare the microhardness of five different resin composites at different irradiation distances (2 mm and 9 mm) by using three light curing units (quartz tungsten halogen, light emitting diodes and plasma arc).

/pdf/the-effect-of-irradiation-distance-on-microhardness-of-resin-43c8utyund.pdf

Ferhan Egilmez

Papers

Micro-shear bond strength of different resin cements to ceramic/glass-polymer CAD-CAM block materials.

Factors affecting the mechanical behavior of Y-TZP.

Does artificial aging affect mechanical properties of CAD/CAM composite materials

Influence of cement thickness on the bond strength of tooth-colored posts to root dentin after thermal cycling

The effect of irradiation distance on microhardness of resin composites cured with different light curing units.