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Background: For anterior teeth with large defects or for teeth which need major changes in color, shape or size, laminate veneers are a highly esthetic and comparatively tissue conservative treatment option within a large group of other therapeutic measures. The survival rates of laminate veneers are > 90% over 10 years and in the range of full coverage crowns. For patients with heavy bruxism and/or small clinical crowns the longevity may be reduced. Objective: to review the main guidelines for dental treatment using laminate veneers. Data Sources: dental literature (Web of Science, PubMed, Google Scholar) about laminate veneers between 1998 and 2019. Study Selection: articles, reviews and textbooks about laminate veneers were selected to obtain the most relevant information. Data Extraction: all data evidence-based about laminate veneers technique were extracted. Data Synthesis: all data considered important and relevant for the laminate veneers technique were presented step by step in a coherent and concise way. The conclusions were: • Preparation should be as conservative as possible (0.3 – 0.5 mm cervical-buccal reduction). • Special methods for impression taking and for temporization should be applied. • The ceramic material needs to have optimal esthetic properties including adequate translucency. • The choice of the luting material is based on optimal bonding (etch & rinse, SE). Solely light curing luting composite materials or flowable composites can be used for optimal and longlasting esthetics for ceramic thickness of up to 1 mm. • In order to protect the laminate veneers against parafunctional forces during night sleep a protective splint (night guard) is recommended.

A methyl methacrylate (MMA) -based resin cement is one of the popular luting agents to bond a dental restorative material in dental treatments. Bond strength of the MMA-based resin cement with adhesive primer to each restorative material is important for clinical success in prosthodontic treatments without debonding or fracture failures of the restoration such as a dental crown and post. However, open data on the bonding properties of combined use of the MMA-based resin cement and appropriate primers is limited. This article provides data on the bond strength and fracture mode of the 4-META/MMA-TBB resin cement (MMA-based resin cement) to the restorative materials (silver alloy, gold alloy, feldspathic porcelain, and zirconia) with four types of primer. Each restorative material was applied with the adhesive primer and bonded with the MMA-based resin cement. The cement-bonded samples were subjected to a thermocycling in which the materials were immersed alternately in water baths at 5 °C and 55 °C for 10,000 cycles. The bond strength between the resin cement and each restorative material was measured by means of a conventional tensile bond strength test. The fracture modes of the examined samples were observed and determined. The measured tensile bond strengths were statistically analysed using one-way analysis of variance (ANOVA), followed by Tukey's multiple comparison test.

Generally speaking, ceramic materials are insensitive to corrosion, compared to most other materials. The present study questions the fact that ceramics are inert. Two major aspects are to be considered: the stability of zirconia over time, the stable tetragonal phase transforming into an unstable monoclinic form, the multitude of manufacturing methods, using various additives, sintering additives, oxides mixing, impurities, grain boundaries, and porosities which strongly influence the corrosion behavior and chemical degradation. In case of the investigated ceramics two paths were pursued:a) Dissolutions of ceramics in a mixture of HNO3 60% and HF 40% ultrapure medium.b) Release of cations from ceramics in various mediums:dental bioceramics in a 0.07 M HCl medium and a 0.1% NaF+0.1% KF medium, ceramics used in jewelry and watchmaking applications in a HCl 0.07 M medium and an artificial sweat medium. By inductively coupled plasma-optical emission spectrometry/mass spectrometry (ICP-OES/MS), traces of significant chemical elements were assessed: Hf, Cr, Y, As, Pb, Al, Fe, Cu, Se, Sb, La, Ni, Co, Sb, Ta, Te, Ba, Sm, Nb, Hg, Cd, Sr, As and Se. In ceramics used in jewelry and watchmaking applications the concentrations found vary from one ceramic to another, including toxic elements such as Te, Ba, As, Pb, Sm, Hg and Cd, therefore being technical zirconia ceramics which are not intended for the medical field. For ceramics used in jewelry and watchmaking applications a screening identification test for Ni, Co, Cu and Fe with strips of type Merckoquant&reg, (Merck, Kenilworth, NJ, USA) was also performed. The obtained data prove that the zirconia ceramics in question are far from being &ldquo, inert&rdquo

Nowadays, there are two different approaches to the treatment of defects of hard tissues of anterior teeth. There is a direct recovery method with composite materials and an indirect method with the usage of ceramic restorations. The issue of choice an optimal method of the preparation of hard tissues for appropriate types of restorations is relevant. Some scientists raised the question of choice between direct composite resin restorative techniques and indirect ceramic techniques. The choice of many authors leaned towards indirect ceramic restoration because of their better physical, mechanical and esthetic properties. Aim. Working on this publication, we wanted to highlight some physical properties of the most commonly used composite resin restoration materials and dental ceramic materials. Object and methods. For the experiment intact teeth (premolars, incisors) were selected (extracted according to orthodontic prescriptions). For the experiment selected teeth were prepared from the vestibular surface to a corresponding depth, within enamel or dentine. Totally 60 teeth were selected (30 prepared within to dentin, 30 with the depth of preparation within the enamel). The technique of determining of the tensile strength means the determining of the destructive force value on the sample. The tests were performed on the universal AUTOGRAPH AGS-J tearing machine, which provides an effort of 0-12 kN. The speed of the clamps of the machine is (5 0,5) mm / min. The tensile strength was calculated by the formula: A = F / S * 0,0981, where: F - the destructive force at which the sample is destroyed, kgf; S - the surface area at which the destruction occurs, cm?. Results and discussion. The results of the studies have shown that the average tensile strength (kgf / cm2 in samples, which have been thermocycled, and prepared within the dentin, for the EsthetX and V generation adhesives was 35.07 6.08; VII generation adhesive - 16,92 1,99; EX3 -32.24 2.83; IPS Empress - 25.86 3.34. In samples prepared without dentine exposure: for the EsthetX and V generation adhesives, on average, was 51.9 5.53; with the VII generation of adhesive - 33.08 2.27; EX 3 - 49.61 8.82; IPS Empress - 34.34 3.84. Conclusions. According to our research, the most effective bonding relationship with hard tooth tissues was present is the composite resin Esthet X in combination with the adhesive of the V generation, and the EX3 fieldspatic ceramics if the preparation was performed within the enamel. The strength of all investigated materials is in the same range, but taking into account the factor of water absorption and aesthetic stability, field-spatic ceramic and leucite glass based ceramic should be considered as the material of choice. Prospects for the further research. This study is promising and requires an augmentation of samples quantity for studying in order to get a greater reliability. Also a promising tactic seems to be further studies of other physical and chemical properties of materials (shear strength, abrasion resistance, color stability etc.).

Made available in DSpace on 2019-10-06T16:20:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01 The use of thin lithium disilicate (LD) occlusal veneers is an effective method to increase the vertical dimension of occlusion in cases of tooth wear. However, doubt remains regarding the threshold thickness to be used in this restoration class. This study aims to evaluate the effect of ceramic thickness on the survival rate and failure pattern of LD molar veneer restorations using a simplified fatigue testing machine. Sixty sound, freshly extracted human molars were used. Three groups (n = 20) were randomly created with different ceramic thicknesses (0.5, 0.8, and 1.2 mm), and 60 LD IPS e.max Press LT occlusal veneers were fabricated. The ceramic restorations were luted with a resin cement. The stainless-steel rotating drum of the ball mill contained 10 zirconia (Y-TZP) and 10 stainless steel spheres, in 500 mL of distilled water at 37 ± 1 °C. Crack growth in the LD restorations was evaluated under a stereomicroscope following each fatigue testing run (12 60-min runs). Progressive damage was observed as a function of cycling time. Survival was significantly influenced by the restoration thickness (p = 0.002, log-rank test), with thicker restorations exhibiting a higher survival rate. Thinner restorations (0.5 mm) showed significantly lower survival rate than 0.8- and 1.2-mm restorations (p < 0.016); no significant difference was observed between the 0.8- and 1.2-mm restorations. A threshold value of 0.8 mm may represent an acceptable compromise between fatigue resistance and tooth reduction. Department of Biomedical and Neuromotor Science Division of Prosthodontics Alma Mater Studiorum University of Bologna Department of Biomedical and Neuromotor Sciences Division of Prosthodontics Alma Mater Studiorum University of Bologna Dental School Alma Mater Studiorum University of Bologna Department of Dental Materials and Prosthodontics Araraquara Dental School Unesp-Univ Estadual Paulista Araraquara Department of Dental Materials and Prosthodontics Araraquara Dental School Unesp-Univ Estadual Paulista Araraquara

This study evaluated the influence of the geometry of ceramic specimens (disc vs. square plate) on the biaxial flexural strength (BFS) using an experimental set and finite element analysis (FEA). Leucite glass-ceramic blocks were used in the preparation of disc (D; n=14) and square plate (S; n=13) specimens with the same lower (tensile) surface area. The specimens were subjected to a piston-on-three-ball flexural test (ISO 6872:2008). To calculate the BFS of the S group, the specimen radius, indicated by the ISO 6872:2008 formula for discs, was replaced by half of the side length. FEA compared the pattern of stress distribution and the first principal stress between D and S specimens having the same and different lower (tensile) surface area. Student’s t-test showed no difference (p=0.85) in the BFS between D (95.0±9.6 MPa) and S (84.3±10.3 MPa). FEA indicated a similar pattern of stress distribution, with almost no difference in the first principal stress of discs and square plates with the same lower (tensile) surface area. In the experimental condition investigated, square plate ceramic specimens can be used in piston-on-three-ball tests. For the calculation of the BFS, the specimen radius may be replaced by half side length of the square specimen.

Bonding orthodontic brackets to ceramic materials is a challenging procedure; femtosecond (FS) laser conditioning could provide improved results, but the ideal settings for effective bracket-zirconia bonding have never been established. This study aimed to analyze the differences in surface roughness and shear bond strength (SBS) produced by different femtosecond laser settings and establish a protocol to prepare zirconia surfaces for optimal adhesion to metal orthodontic brackets. One hundred eighty zirconia samples were assigned to six groups according to surface treatment: (1) control; (2) air-particle abrasion (APA); (3) FS laser irradiation (300 mW output power, 60 μm inter-groove distance); (4) FS laser irradiation (200 mW, 100 μm); (5) FS laser irradiation (40 mW, 60 μm); and (6) FS laser irradiation (200 mW, 60 μm). Surface roughness was measured. Orthodontic brackets were bonded to the zirconia specimens, and SBS was measured. SBS in groups 3 and 6 was significantly higher than the other groups (5.92 ± 1.12 MPa and 5.68 ± 0.94 MPa). No significant differences were found between groups 1, 2, 4, and 5 (3.87 ± 0.77 MPa, 4.25 ± 0.51 MPa, 3.74 ± 0.10 MPa, and 3.91 ± 0.53 MPa). Surface roughness was significantly greater for FS laser than for control and APA groups (p = 1.28 × 10−8 ). FS laser at 200 mW, 60 μm can be recommended as the ideal settings for treating zirconia surfaces, producing good SBS and more economical energy use.

Ceramics and glass-ceramics are materials of choice for dental crowns due to their attractive hardness, biocompatibility, etc. However, a major problem with their usage is the observed high wear of either the opposing dental enamel or both the enamel and ceramic itself. Although these issues have been known for some time, the responsible wear mechanism(s) are not clearly identified. Accordingly, an in vitro investigation was undertaken to identify the mechanism(s) responsible for the wear of a popular leucite glass-ceramic (LGC) dental prosthesis material when opposing both itself and human dental enamel. Reciprocating sliding wear tests were carried out with LGC or enamel cusp sliding on LGC flat-surface samples with varying surface roughness. The wear loss was quantified using profilometry and the wear scar surface and subsurface were analysed using electron microscopy techniques to reveal the underlying wear mechanism. The present results revealed that the dominant wear mechanism for LGC, when opposed by LGC or enamel, was micro-abrasion due to lateral crack formation/extension. Leucite crystals in the ceramic׳s microstructure appear to act as hard asperities and their loading/unloading during sliding contact caused the formation and extension of lateral cracks and, consequently, wear of the LGC dental material. For human enamel, the dominant wear mechanism was delamination.

Conventional sintering techniques for zirconia-based materials, which are commonly used in dental reconstruction, may not provide uniform heating, with the consequent generation of microstructural flaws in the final component. A sintering system using microwave heating may represent a viable alternative. The purpose of this study was to compare the dimensional variation and physical and microstructural characteristics of commercial zirconia (Y-TZP), used as a dental restoration material, sintered in conventional and microwave furnaces. A physical-mineralogical-microstructural characterisation was carried out to evaluate the level of densification and the presence of flaws in the sintered specimens. Use of the microwave systems allowed the length of the sintering cycle to be reduced to a few minutes, compared with the several hours necessary with a ‘traditional’ heating system. Additionally, the maximum temperature used to reach the required density decreased from 1450–1480 °C with the electric furnace to 1200 °C in the microwave furnace. An important clinical implication is that the reduced sintering time could allow the introduction of zirconia in chair-side treatments, if used as a monolithic material.

PURPOSE Surface color is one of the main criteria to obtain an ideal esthetic. Many factors such as the type of the material, surface specifications, number of firings, firing temperature and thickness of the porcelain are all important to provide an unchanged surface color in dental ceramics. The aim of this study was to evaluate the color changes in dental ceramics according to the material type and glazing methods, during the multiple firings. MATERIALS AND METHODS Three different types of dental ceramics (IPS Classical metal ceramic, Empress Esthetic and Empress 2 ceramics) were used in the study. Porcelains were evaluated under five main groups according to glaze and natural glaze methods. Color changes (ΔE) and changes in color parameters (ΔL, Δa, Δb) were determined using colorimeter during the control, the first, third, fifth, and seventh firings. The statistical analysis of the results was performed using ANOVA and Tukey test. RESULTS The color changes which occurred upon material-method-firing interaction were statistically significant (P

Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-27T11:28:45Z No. of bitstreams: 0 Made available in DSpace on 2014-05-27T11:28:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-04-01 Objectives: This study investigated the effect of extreme cooling methods on the flexural strength, reliability and shear bond strength of veneer porcelain for zirconia. Methods: Vita VM9 porcelain was sintered on zirconia bar specimens and cooled by one of the following methods: inside a switched-off furnace (slow), at room temperature (normal) or immediately by compressed air (fast). Three-point flexural strength tests (FS) were performed on specimens with porcelain under tension (PT, n = 30) and zirconia under tension (ZT, n = 30). Shear bond strength tests (SBS, n = 15) were performed on cylindrical blocks of porcelain, which were applied on zirconia plates. Data were submitted to one-way ANOVA and Tukey's post hoc tests (p < 0.05). Weibull analysis was performed on the PT and ZT configurations. Results: One-way ANOVA for the PT configuration was significant, and Tukey's test revealed that fast cooling leads to significantly higher values (p < 0.01) than the other cooling methods. One-way ANOVA for the ZT configuration was not significant (p = 0.06). Weibull analysis showed that normal cooling had slightly higher reliability for both the PT and ZT configurations. Statistical tests showed that slow cooling decreased the SBS value (p < 0.01) and showed less adhesive fracture modes than the other cooling methods. Clinical Significance: Slow cooling seems to affect the veneer resistance and adhesion to the zirconia core; however, the reliability of fast cooling was slightly lower than that of the other methods. © 2013 Elsevier Ltd. UNESP-Univ Estadual Paulista Faculdade de Odontologia de Araraquara, R. Humaitá, 1680 Sala 415, Centro. Araraquara, SP 14801-903 Universidade Do Estado Do Rio de Janeiro Faculdade de Tecnologia de Resende, Etr Resende-Riachuelo S/N, Morada da Colina, Resende, RJ 27523-000 UNESP-Univ Estadual Paulista Faculdade de Odontologia de Araraquara, R. Humaitá, 1680 Sala 415, Centro. Araraquara, SP 14801-903

Made available in DSpace on 2018-12-11T17:00:22Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-07-01 Yttria-stabilized tetragonal zirconia (Y-TZP) was introduced as ceramic implant abutments due to its excellent mechanical properties. However, the damage patterns for Y-TZP abutments are limited in the literature. Fractographic analyses can provide insights as to the failure origin and related mechanisms. The purpose of this study was to analyze fractured Y-TZP abutments to establish fractographic patterns and then possible reasons for failure. Thirty two prefabricated Y-TZP abutments on external hex implants were retrieved from a single-load-to failure test according to the ISO 14801. Fractographic analyses were conducted under polarized-light estereo and scanning electro microscopy. The predominant fracture pattern was abutment fracture at the connecting region. Classic fractographic features such as arrest lines, hackle, and twist hackle established that failure started where Y-TZP abutments were in contact with the retention screw edges. The abutment screw design and the loading point were the reasons for localized stress concentration and fracture patterns. UNESP - University Estadual Paulista Araraquara School of Dentistry Department of Dental Materials and Prosthodontics, 1680 USP - University of São Paulo School of Dentistry Department of Biomaterials and Oral Biology, 2227 Western University Schulich School of Medicine and Dentistry Department of Medical Biophysics, Medical Sciences Building Western University Schulich School of Medicine and Dentistry Department of Dentistry, Medical Sciences Building UNESP - University Estadual Paulista Araraquara School of Dentistry Department of Dental Materials and Prosthodontics, 1680

Three cases of trilayered fixed dental prostheses fractured in vivo are fractographically analyzed to identify causes of failure. In all cases fractures initiated from a preexistent crack/defect in the zirconia framework produced previous to the fusion firing of a lithium disilicate veneering ceramic. In two cases zirconia framework pre-cracks were found to have been infiltrated with the intermediate fusion glass that diffused therein during sintering. This report highlights the susceptibility of zirconia to grinding damage and its role in limiting the lifetime of zirconia-based fixed dental prostheses.

Background: Titanium alloys has been used as an alternative to nickel-chromium alloys for metal-ceramic restorations because of its good biocompatibility and mechanical properties. This indicated that it was possible to design coping according to standards established for metal-ceramics. However, titanium is chemically reacting strongly with gaseous elements which causes problems when ceramics are fused to titanium. Purpose: To provide information about improving the bonding between titanium and ceramic. Review: Titanium has two crystal modifications, the close-packed hexagonal (α) structure, up to 880° C, and above this temperature the bodycentered cubic (β) structure. The principal problems is the extensive dissolution of oxygen resulting in thick, oxygen-rich titanium layers called α-case that harms the bonding of ceramic to titanium and the great mismatch in the coefficient of thermal expansion of conventional ultra-low fusing ceramic. Methods have been developed for fusing ceramic to titanium like processing methods, the used of ultra-low fusing titanium ceramic, bonding agent, and protocol for ceramic bonding to titanium. Conclusion: Titanium and titanium alloys, based on their physical and chemical properties suitable for titanium-ceramic restorations, but careful selection of processing methods, ceramic materials, laboratory skill and strict protocol for ceramic bonding to titanium are necessary to improve the bonding between titanium and ceramic.Latar Belakang: Logam campur titanium telah dipakai sebagai salah satu bahan alternatif untuk logam nikel-krom pada pembuatan restorasi keramik taut logam karena mempunyai biokompatibilitas dan sifat mekanik yang baik. Hal ini menunjukkan bahwa logam titanium dapat dipakai untuk pembuatan koping logam berdasarkan standar yang dipakai untuk pembuatan restorasi keramik taut logam. Meskipun, secara kimiawi logam titanium bereaksi dengan elemen-elemen gas yang menyebabkan masalah pada perlekatan keramik pada titanium. Tujuan: Memberikan informasi tentang cara meningkatkan kekuatan perlekatan antara keramik dengan titanium. Tinjauan: Titanium mempunyai 2 struktur kristal, struktur close-packed hexagonal (α) diatas 880°C dan struktur bodycentered cubic (β) dibawah 883°C. Masalah utama adalah pelepasan gas oksigen yang menghasilkan lapisan titanium kaya oksigen yang tebal disebut α-case yang menghalangi perlekatan keramik pada titanium dan koefisien ekspansi panas dari bahan ultra-low fusing ceramic yang berbeda dengan titanium. Berbagai cara telah dikembangkan untuk mendapatkan perlekatan keramik pada titanium seperti teknik pembuatan, pemakaian bahan ultra-low fusing titanium ceramic, bahan bonding dan protokol untuk perlekatan bahan keramik pada titanium. Kesimpulan: Titanium dan logam campur titanium, berdasarkan sifat-sifat mekanik dan kimiawinya dapat dipakai untuk pembuatan restorasi keramik taut logam, tetapi pemilihan teknik pembuatan, bahan keramik, ketrampilan peteknik gigi dan mengikuti protokol untuk mendapatkan perlekatan keramik pada titanium dengan benar diperlukan untuk meningkatkan kekuatan perlekatan antara keramik dan titanium.

Fractographic analysis of clinically failed dental ceramics can provide insights as to the failure origin and related mechanisms. One anterior 6­unit all­ceramic zirconia fixed partial denture (FPD) (Cercon R) has been clinically recovered and examined using qualitative fractography. The purpose was to identify the fracture origin and to state the reasons for failure. The recovered parts of the zirconia FPD were microscopically examined to identify classic fractographic patterns such as arrest lines, hackle, twist hackle and wake hackle. The direction of crack propagation was mapped and interpreted back to the origin of failure at the interface of the occlusal–palatal tip of the core and the veneering ceramic. An inappropriate core drop design favoring localized stress concentration combined with a pore cluster in the veneering ceramic at the core tip interface were the reasons for this premature through­the­core thickness failure.

Purpose: This study investigated and compared the surface roughness achieved by glazing porcelain samples in a conventional and a microwave oven. Materials and Methods: Two commercial brands of metal ceramics were used, VITA VMK MASTER and IPS CLASSIC. Sixty samples were fabricated, 30 for each type of ceramic. The samples were sintered in the conventional oven and hand-polished to remove any irregularities. Samples (n = 10) from each type of ceramic were further divided into three groups as follows: hand-polished (Group A), conventional oven glazed (Group B), and microwave glazed (Group C). Each specimen was evaluated for surface roughness by atomic force microscope. Data were statistically analyzed using two-way analysis of variance (ANOVA) and Tukey's post hoc test (a = 0.05). Results: Two-way ANOVA indicated a highly significant difference in surface roughness based on the type of glazing (P < 0.001), there was a significant difference based on the metal ceramics (P = 0.002). There was also a significant interaction between the type of glazing and metal ceramics (P = 0.009). The images obtained from the atomic force microscope corroborated the measured values. Conclusions: All the results indicate that microwave glazing can be a feasible option for glazing porcelain specimens. It was concluded that surface topography is influenced by surface treatment and microwave glazed ceramic is superior to conventional oven glazed ceramic and hand-polishing showed greater surface roughness when compared to glazing. IPS CLASSIC ceramic showed relatively smooth surface when compared to VITA VMK MASTER irrespective of the surface treatment.

Aim: This study aims to evaluate the microshear bond strength of zirconia-based ceramics with different resin cement systems and surface treatments. Materials and Methods: Forty blocks of zirconia-based ceramic were prepared and embedded in polyvinyl chloride (PVC) tubes with acrylic resin. After polishing, the samples were washed in an ultrasonic bath and dried in an oven for 10 min. Half of the samples were subjected to sandblasting with aluminum oxide. Blocks were divided into four groups (n = 10) in which two resin cements were used as follows: (1) RelyX™ U100 with surface-polished zirconia; (2) RelyX™ U100 with surface-blasted zirconia; (3) Multilink with surface-polished zirconia; and 4) Multilink with surface-blasted zirconia. After performing these surface treatments, translucent tubes (n = 30 per group) were placed on the zirconia specimens, and resin cement was injected into them and light cured. The PVC tubes were adapted in a universal testing machine; a stiletto blade, which was bolted to the machine, was positioned on the cementation interface. The microshear test was performed at a speed of 0.5 mm/min. Failure mode was analyzed in an optical microscope and classified as adhesive, cohesive, or mixed. Results: The null hypothesis of this study was rejected because there was a difference found between the resin cement and the surface treatment. There was a statistical difference (P < 0.005) in RelyX™ U100 with surface-blasted zirconia, in relation to the other three groups. For Multilink groups, there was no statistical difference between them. Conclusion: Self-adhesive resin cement showed a more significant tendency toward bond strength in the ceramic-based zirconium oxide grit-blasted surfaces.

This study investigated the influence of ceramic compositions on Knoop Hardness Number (KHN) immediately and 24 h after polymerization and the effect of activation modes on the KHN of a resin cement. Ten Panavia F 2.0 resin cement discs were activated either directly using curing light, or chemically without light, or through 1.2-thick ceramic discs. The following ceramics were evaluated: Duceram, Cergogold, IPS Empress, IPS Empress 2, Procera, Cercon, In Ceram Alumina and In Ceram Zirconia. The KHN was obtained immediately and after 24-h testing time. Two-way ANOVA and Tukey's test were performed for statistical analysis (p

The aim of this study was to evaluate the Knoop hardness after 15 min and 24 h of different shades of a dual-cured resin-based cement after indirect photoactivation (ceramic restoration) with 2 light-curing units (LCUs). The resin cement Variolink II (Ivoclar Vivadent) shade XL, A2, A3 and opaque were mixed with the catalyst paste and inserted into a black Teflon mold (5 mm diameter x 1 mm high). A transparent strip was placed over the mold and a ceramic disc (Duceram Plus, shade A3) was positioned over the resin cement. Light-activation was performed through the ceramic for 40 s using quartz-tungsten-halogen (QTH) (XL 2500; 3M ESPE) or light-emitting diode (LED) (Ultrablue Is, DMC) LCUs with power density of 615 and 610 mW/cm2, respectively. The Koop hardness was measured using a microhardness tester HMV 2 (Shimadzu) after 15 min or 24 h. Four indentations were made in each specimen. Data were subjected to ANOVA and Tukey's test (a=0.05). The QTH LCU provided significantly higher (p

The objective of this study was to investigate how mechanical surface treatments performed for removal of excess of molten glass, influence the fracture toughness of a dental zirconia toughened alumina (In-Ceram® Zirconia). Infiltrated ZTA disks were submitted to three different surface treatments (grinding, sandblasting and grinding + sandblasting + annealing). Fracture toughness was accessed through indentation strength test (IS). X ray diffraction was used to investigate the metastability of tetragonal zirconia particles under all treatments proposed. Kruskall-Wallis non-parametrical test and Weibull statistics were used to analyze the results. Grinding (group 1) introduced defects which decreased the fracture toughness and reliability, presenting the lowest K IC. On the other hand, grinding followed by sandblasting and annealing (group 3) presented the highest K IC. Sandblasting (group 2) presented the highest reliability but lower K IC compared to group 3.

Translucency of dental ceramics, esthetic posts and orthodontic brackets was reviewed. Translucency parameter (TP) and contrast ratio (CR) are generally used for translucency evaluation. For the evaluation of translucency, two criteria such as the translucency of human teeth (TP = 15–19, 1 mm thick) and the visual perceptibility threshold for the translucency difference (∆CR > 0.07 or ∆TP > 2) were used. In ceramics, translucency differences were in the perceptible range depending on the type of material and the thickness. However, variations caused by the difference in the required thickness for each layer by the material and also by the measurement protocols should be considered. As to the translucency of esthetic posts, a significant difference was found among the post systems. Translucency was influenced by the bracket composition and brand, and the differences by the brand were visually perceptible.

The aim of this study was to investigate the influence of light source, LED unit and halogen lamp (HL), on the effectiveness of Enforce dual-cured cement cured under a ceramic disc. Three exposure times (60, 80 and 120 s) were also evaluated. Two experimental groups, in which the polymerization of the dual-cured cement was performed through a ceramic disc, and two control groups, in which the polymerization of the dual-cured cement was performed directly without presence of ceramic disc were subdivided into three subgroups (three different exposure times), with five specimens each: G1A- HL 60s; G1B- HL 80s; G1C- HL 120s; G2A- LED 60s; G2B- LED 80s; G2C- LED 120s; and control groups: G3A- HL 60s; G3B- HL 80s; G3C- HL 120s; G4A- LED 60s; G4B- LED 80s and G4C- LED 120s. Cement was applied in a steel matrix (4mm diameter, 1.2mm thickness). In the experimental groups, a ceramic disc was placed on top. The cement was light-cured through the ceramic by a HL and LED, however, the control groups were cured without the ceramic disc. The specimens were stored in a light-proof container at 37ºC for 24 hours, then Vickers hardness was determined. A four-way ANOVA and Tukey test (p£ 0.05) were performed. All specimens cured by LED for 60s showed inferior values compared with the halogen groups. In general, light-curing by LED for 80s and 120s was comparable to halogen groups (60s and 80s) and their control groups. LED technology can be viable for light-curing through conventional ceramic indirect restorations, when curing time is increased in relation to HL curing time. O objetivo deste estudo foi estudar a influência da fonte de luz, LED e lâmpada halógena (LH), na efetividade de polimerização do cimento resinoso dual Enforce fotoativado sob um disco de porcelana. Três tempos de exposição (60, 80 e 120 segundos) foram também avaliados. Dois grupos experimentais, na qual a polimerização do cimento resinoso foi feita através de um disco cerâmico, e dois controles, polimerização direta do cimento, sem presença do disco cerâmico foram subdivididos em três subgrupos, com cinco amostras em cada: G1A- LH 60s; G1B- LH 80s; G1C- LH 120s; G2A- LED 60s; G2B- LED 80s; G2C- LED 120s; e grupos controles: G3A- LH 60s; G3B- LH 80s; G3C- LH 120s; G4A- LED 60s; G4B- LED 80s e G4C- LED 120s. O cimento resinoso foi inserido em uma matriz de aço (4 mm de diâmetro e 1,2 mm de espessura). Nos grupos experimentais um disco de porcelana (6 mm de diâmetro por 2 mm de espessura) foi colocado sobre o cimento. Este foi fotoativado através da porcelana pela lâmpada halógena e pelo LED, por outro lado nos grupos controles a luz foi aplicada sem o disco de porcelana. As amostras foram armazenadas em um frasco que impedia a passagem de luz a 37(0)C por 24 horas, para que depois a dureza Vickers fosse determinada. Os dados foram submetidos à análise de variância a quatro critérios seguido pelo teste Tukey (p£ 0,05). Todas as amostras polimerizadas pelo LED por 60s mostraram valores inferiores quando comparadas com as do grupo da lâmpada halógena. Em geral, a fotoativação realizada por 80 e 120 s com o LED foi estatisticamente similar à fotoativação com a lâmpada halógena (60 e 80 s). A tecnologia LED pode ser viável para a fotoativação de restaurações indiretas de porcelana quando o tempo de polimerização é aumentado.

Introduction Badly broken or structurally compromised posterior teeth are frequently associated with crown/root fracture. Numerous restorative materials have been used to fabricate indirect full-coverage restorations for such teeth. This study aims to evaluate and compare the effect of restorative materials on the stress distribution pattern in a mandibular first molar tooth, under varying loading conditions and to compare the stress distribution pattern in five commonly used indirect restorative materials. Materials and methods Five three-dimensional finite element models representing a mandibular first molar tooth restored with crowns of gold, porcelain fused to metal, composite (Artglass), alumina-based zirconia (In-Ceram Zirconia [ICZ]), and double-layered zirconia-based materials (zirconia core veneered with porcelain, Lava) were constructed, using a Finite Element Analysis Software (ANSYS version 10; ANSYS Inc., Canonsburg, PA, USA). Two loading conditions were applied, simulating maximum bite force of 600 N axially and normal masticatory bite force of 225 N axially and nonaxially. Results Both all-ceramic crowns allowed the least amount of stress distribution to the surrounding tooth structure. In maximum bite force-simulation test, alumina-based all-ceramic crown displayed the highest von Mises stresses (123.745 MPa). In the masticatory bite force-simulation test, both all-ceramic crowns (122.503-133.13 MPa) displayed the highest von Mises stresses. Conclusions ICZ crown displayed the highest peak von Mises stress values under maximum and masticatory bite forces. ICZ and Lava crowns also allowed the least amount of stress distribution to the surrounding tooth structure, which is indicative of a favorable response of the underlying tooth structure to the overlying full-coverage indirect restorative material. These results suggest that ICZ and Lava crowns can be recommended for clinical use in cases of badly damaged teeth.

Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-27T11:26:01Z No. of bitstreams: 0Bitstream added on 2014-05-27T14:36:24Z : No. of bitstreams: 1 2-s2.0-80052469864.pdf: 2599552 bytes, checksum: 9e2dcd484458d54c8f32808ed241d747 (MD5) Made available in DSpace on 2014-05-27T11:26:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-10-01 Ceramics have been widely used for esthetic and functional improvements. The resin cement is the material of choice for bonding ceramics to dental substrate and it can also dictate the final esthetic appearance and strength of the restoration. The correct use of the wide spectrum of resin luting agents available depends on the dental tooth substrate. This article presents three-year clinical results of a 41 years old female patient B.H.C complaining about her unattractive smile. Two all-ceramic crowns and two laminates veneers were placed in the maxillary incisors and cemented with a self-adhesive resin luting cement and conventional resin luting cement, respectively. After a three-year follow-up, the restorations and cement/teeth interface were clinically perfect with no chipping, fractures or discoloration. Proper use of different resin luting cements shows clinical appropriate behavior after a three-year follow-up. Self-adhesive resin luting cement may be used for cementing all-ceramic crowns with high predictability of success, mainly if there is a large dentin surface available for bonding and no enamel at the finish line. Otherwise, conventional resin luting agent should be used for achieving an adequate bonding strength to enamel. Sao Paulo State University-UNESP Faculty of Dentistry of Araçatuba Department of Dental Materials and Prosthodontics, Sao Paulo Sao Paulo State University-UNESP Faculty of Dentistry of Araçatuba Department of Dental Materials and Prosthodontics, Sao Paulo

PURPOSE The aim of this in vitro study was to examine the curing efficiency of various resin-based materials polymerized through ceramic restorations with 3 different thicknesses. Curing efficiency was evaluated by determining the surface microhardness (VHN) of the resin specimens. MATERIALS AND METHODS Four kinds of resin materials were used. Z350 (3M ESPE Filtek™ Z350: A2 Shade), Z250 (3M ESPE Filtek™ Z250: A2 Shade) and Variolink® II (VL: Ivoclar vivadent, base: transparent) either with or without a self-curing catalyst (VLC: Ivoclar vivadent, catalyst: low viscosity/transparent) were filled into the silicone mold (10 mm diameter, 1 mm thick). They were cured through ceramic discs (IPS e.max Press MO-0 ingot ivoclar vivadent, 10 mm diameter, 0.5, 1 and 2 mm thicknesses) by LED light-curing units for 20 and 40 seconds. Vicker's microhardness numbers (VHNs) were measured on the bottom surfaces by a microhardness tester. Data were analyzed using a 3- way analysis of variance (ANOVA) at a significance level of 0.05. RESULTS The thickness of ceramic disc increased, the VHNs of all four resin types were decreased (P

This review presents a critical survey of all experimental data about the low temperature degradation of zirconia (often referred to as "aging") due to the tetragonal-to-monoclinic transformation, which have been collected at temperatures of interest for dental application (room temperature to about 100 degrees C). It is shown that the main factors affecting the aging phenomenon are (i) the stabilizer type and content, (ii) the residual stress and (iii) the grain size. It is also shown that extrapolating the low temperature degradation rate from accelerated aging tests can lead to unacceptable conclusions about the lifetime of the zirconia-based components. Finally, based on the experimental evidence, a set of engineering guidelines for the use of zirconia in restorative and prosthetic dentistry is proposed.

Interest is increasing in the development of new methodologies for accidental dose assessment, exploiting the luminescence and dosimetric properties of objects and materials which can be usually found directly on exposed subjects and/or in the contaminated area. In this work, several types of ceramics employed for dental prosthetics restoration, including both innovative materials used as sub-frames for the construction of the inner part of dental crowns (core), and conventional porcelains used for the fabrication of the external layer (veneer), were investigated with regard to their thermally and optically stimulated luminescence (TSL and OSL respectively) properties, in view of their potential application in accidental dosimetry. The sensitivity to ionizing radiation proved to strongly depend on the type and brand of ceramic, with minimum detectable dose ranging from few mGy up to several tens of mGy. A linear dose–response was observed for most of the samples. However, the luminescence signals were characterised by a significant fading, which has to be taken into account for a reliable accidental dose assessment after a radiation exposure event.

Ceramics are attractive dental materials as a result of their supe- rior aesthetics and biocompatibility. However, they are brittle and prone to premature failure, especially at repeated contact strain and in moist environments. The chemical stability of dental ceramics is important, because it directly affects mechanical properties and aesthetic value of restorations. The aim of this study was to investigate the effects of a corrosive agent, i.e. 4% acetic acid, on the surface of glazed and unglazed feldspathic ceramics. Metal-ceramic plates (9.0 × 9.0 × 1.2 mm) composed of a Ni-Cr alloy (Wiron 99, Bego Germany) and glazed or unglazed feldspathic ceramics (IPS Classic, Ivoclar-Vivadent, Schaan, Liechtenstein) were prepared according to the manufacturer‧s instructions. The samples were immersed in the solution at 80 °C and kept there for 16 h (ISO 6872). The surfaces of the samples before and after immersion in the corrosive medium were examined by atomic force microscopy (AFM). The pre- and post- corrosion AFM images of the surfaces of the feldspathic ceramics samples clearly show that the glazed surfaces are much less prone to deterioration by corrosion than the unglazed ones.

Objective: The purpose of this study was to determine the crack resistance behavior (KR) of human enamel in relation to its microstructure. Methods: Human molar teeth were precision cut, polished and tested using Vickers micro-indentation at different loads ranging from 0.98 to 9.8 N. Five indentation load levels were considered, 20 indentation cracks for each load level were introduced on the surface of the test specimen (10 indentations per tooth) and their variability was evaluated using Weibull statistics and an empirical model. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to analyze the crack morphology and propagation mechanisms involved. Results: The results showed that enamel exhibited increasing cracking resistance (KR) with increasing load. It was found that the crack propagation mainly depended on the location and the microstructure it encountered. SEM showed the formation of crack bridges and crack deflection near the indentation crack tip. The crack mode was of Palmqvist type even at larger loads of 9.8 N. This was mainly attributed to the large process zone created by the interwoven lamellar rod like microstructure exhibited by the enamel surface. Significance: This study shows that there are still considerable prospects for improving dental ceramics and for mimicking the enamel structure developed by nature. © 2009 Academy of Dental Materials.

The differences of translucency and transparency request special conditions for a right photographic presentation and for correct transmission measurements. These differences also influence the materials design of products because of the effect of thickness. Prerequisites of a clear transparency of ceramics are derived for inherent materials properties and for the microstructures starting from a comparison of amorphous, single crystalline and sintered polycrystalline transparent materials. Manufacturing principles differ for transparent cubic and non-cubic ceramics; they have to respond to frequently extreme microstructural requirements, to the available basis of raw materials, and to individual shape, size, and property objectives of applications. A range of present and future applications is addressed and evaluated as governed by, on the one hand, a sensible balance of stringent needs in different fields of the industry with, on the other hand, the costs of development and manufacture.

During fabrication of bonded ceramic restorations, cervical adaptation, occlusal adjustment and final finishing/polishing are procedures to be performed at the dental office after adhesive cementation. Final adjustments may result in loss of ceramic glaze, which requires new polishing of the ceramic surface, with special attention for selection of adequate materials and instruments. The purpose of this study was to evaluate the efficiency of different vehicles associated with diamond pastes indicated for dental ceramic polishing. Two polishing pastes (Crystar Paste and Diamond Excell) associated with four vehicles (rubber cup, Robinson bristle brush, felt wheel and buff disc) were evaluated. Disc-shaped specimens were fabricated from Ceramco II dental ceramic. Surface roughness means (Ra) of the ceramic specimens were determined with a rugosimeter. Data were analyzed statistically by two-way ANOVA and Tukey's test at 5% significance level. There was no statistically significant difference (p>0.01) between the polishing pastes. However, there were statistically significant differences (p0,01) entre as pastas de polimento avaliadas. Contudo, houve diferença significante (p

Using ceramic materials for an automatic production of ceramic dentures by CAD/CAM is a challenge, because many technological, medical, and optical demands must be considered. The IPS Empress 2 framework ceramic meets most of them. This study shows the possibilities for machining this ceramic with economical parameters. The long life-time requirement for ceramic dentures requires a ductile machined surface to avoid the well-known subsurface damages of brittle materials caused by machining. Slow and rapid damage propagation begins at break outs and cracks, and limits life-time significantly. Therefore, ductile machined surfaces are an important demand for machine dental ceramics. The machining tests were performed with various parameters such as tool grain size and feed speed. Denture ceramics were machined by jig grinding on a 5-axis CNC milling machine (Maho HGF 500) with a high-speed spindle up to 120,000 rpm. The results of the wear test indicate low tool wear. With one tool, you can machine eight occlusal surfaces including roughing and finishing. One occlusal surface takes about 60 min machining time. Recommended parameters for roughing are middle diamond grain size (D107), cutting speed v(c) = 4.7 m/s, feed speed v(ft) = 1000 mm/min, depth of cut a(e) = 0.06 mm, width of contact a(p) = 0.8 mm, and for finishing ultra fine diamond grain size (D46), cutting speed v(c) = 4.7 m/s, feed speed v(ft) = 100 mm/min, depth of cut a(e) = 0.02 mm, width of contact a(p) = 0.8 mm. The results of the machining tests give a reference for using IPS Empress(R) 2 framework ceramic in CAD/CAM systems.

The objective of this work was to evaluate the cyclic fatigue strength of a commercial pre-sintered tetragonal zirconia ceramics for dental systems, and to determine the main mechanical properties. Samples were sintered in air at 1600 °C for 120 min with heating and cooling rate of 10 °C/min. The sintered specimens were characterized by X-ray diffraction and scanning electron microscopy. Hardness and fracture toughness were determined using the Vicker's indentation method. The strength was determined by four-point bending tests. The cyclic fatigue tests were realized as four-point bending tests within a frequency of 25 Hz and a stress ratio R of 0.1. The Weibull analysis was employed in order to perform failure probability calculations. Sintered specimens presented average values of hardness, fracture toughness and bending strength near to 13.5 GPa, 8 MPa m 1/2 and 900 MPa, respectively. The fatigue tests results allow concluding that the fatigue strength limit over 5 × 10 6 stress cycles is about 550 MPa or around 63% of the static strength of this material. The tetragonal–monoclinic (t–m) zirconia transformation observed by X-ray diffraction of fractured surfaces occurs during cyclic loading and the fracture of specimens. The 3Y-TZP samples clearly present a range of loading conditions where cyclic fatigue can be detected. The fatigue strength limit around 550 MPa is appropriate for application in dental implant parts.

Made available in DSpace on 2022-05-02T14:14:50Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-01-01 The aim of this paper was to evaluate the influence of different surface treatments on the flexural strength of a pressable lithium disilicate ceramic. Sixteen bars (16x2x4 mm) were made, divided into subgroups (n = 10), and the following surface treatments were done: C - no treatment; H - etching with 5% hydrofluoric acid; HC - etching with 5% hydrofluoric acid, silanization, and cementation; N – etching with 5% hydrofluoric acid, neutralization with supersaturated solution of sodium bicarbonate, silanization, and cementation; U – etching with 5% hydrofluoric acid, ultrasonic cleaning in distillated water, silanization, and cementation; NU - etching with 5% hydrofluoric acid, neutralization with supersaturated solution of sodium bicarbonate, ultrasonic cleaning in distillated water, silanization and cementation. The three points flexural strength was performed 24 h after cementation and the data were analyzed using one-way ANOVA and Tukey’s tests (p-value = 0.05). The results showed that the surface treatment had a significant effect (p-value < 0,05) on the flexural strength of the studied ceramic. The N and NU groups showed lower flexural strength than other groups. Thus, it was concluded that neutralization with supersaturated solution of sodium bicarbonate, followed or not by ultrasonic cleaning results in lower mechanical strength of a pressable lithium disilicate ceramic. The etching with 5% hydrofluoric acid did not reduce the flexural strength of this ceramic type. Institute of Science and Technology UNESP – Univ Estadual Paulista, José Longo, 777, São Dimas Institute of Science and Technology UNESP – Univ Estadual Paulista, José Longo, 777, São Dimas