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This study investigated the fracture load of implant-supported zirconia crowns (IZCs), in which indirect composite resin or feldspathic porcelain was layered onto zirconia frameworks with mechanical retentive devices. Three different zirconia frameworks were assessed: attaching mechanical retentive devices on glaze and opaque porcelain materials (GL and OP groups, respectively), and no attaching mechanical retentive devices (ND group). The frameworks were layered using feldspathic porcelain (FP veneer) and indirect composite resin (IC veneer). Fracture load of the specimens was measured. In FP veneer, the GL group recorded the highest fracture load. In the IC veneer, the GL and OP groups had significantly higher fracture load than the ND group. The fracture resistance of IZCs can be enhanced by applying glaze material before attaching mechanical retentive devices for porcelain layering. The mechanical retentive devices effectively yielded mechanical interlocking between the zirconia frameworks and the IC veneer in GL and OP groups. [ABSTRACT FROM AUTHOR]

In this study, we investigated the effects of surface treatment on the fracture strength of porcelain-veneered zirconia. Highly translucent 4 mol% yttria-stabilized zirconia disks (KATANA HT, Kuraray Noritake Dental) were divided into three surface-treatment groups: 1) as-sintered, 2) alumina sandblasted, and 3) ground. Crystallographic and surface-roughness analyses were conducted for each group. Veneering ceramics (Cerabien ZR, Kuraray Noritake Dental) were applied to the zirconia surfaces. The fracture strengths of the porcelain-veneered zirconia disks were measured using biaxial flexural-strength tests. Crystallographic analysis revealed that grinding and sandblasting increased the fractions of the monoclinic and rhombohedral zirconia phases. The ground specimens had a higher surface roughness than the sandblasted specimens. Weibull analysis showed no significant differences in biaxial flexural strength among the three groups. The results suggest that these surface treatments do not affect the fracture strength of porcelainveneered zirconia. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the effects of ceramic microbeads on the bond strength between resin and zirconia. Microbeads made of zirconia (TZ) and zircon (ZS) were treated with and without hydrofluoric acid (HF). The microbeads were sintered to zirconia disks using intermediate feldspathic porcelains. Two control groups, NB (without microbeads) and AS (without porcelain and microbeads), were also prepared. All specimens were treated with a phosphate primer and veneered with a light-curing resin composite. The 24-h shear bond strengths were determined and analyzed by the Tukey-Kramer test (a=0.05, n=10). The TZ-HF specimen exhibited the highest bond strength, followed by TZ, ZS-HF, ZS, AS, and NB. Scanning electron microscopy observations revealed that the TZ-HF specimen had a complicated debonded surface, and it included microconcavities where the microbeads were detached. Sintering etched zirconia beads onto a zirconia framework with feldspathic porcelains is useful for bonding layered resin composite materials. [ABSTRACT FROM AUTHOR]

Phosphoric acid (PA) etchants are widely used for the bonding pretreatment of teeth; however, their influences on the bonding between glass-ceramics and resin cement have not been clarified yet. This study investigated the effect of a thickening agent on the bonding strength between feldspar porcelain treated with a PA etchant and resin cement with a silane coupling agent. The experiments were performed using two PA etchants: commercial one and prepared one consisting a PA aqueous solution and poly(ethylene glycol) thickening agent. The samples were evaluated by shear bond strength testing, scanning electron microscopy, and Fourier-transform infrared spectroscopy. The obtained results revealed that the thickening agent adhered to the porcelain surface and inhibited cement bonding. Meanwhile, PA remained on the surface due to the presence of the thickening agent and activated the silane coupling agent. Overall, the PA etchant did not improve the bond durability. [ABSTRACT FROM AUTHOR]

This study evaluated bond strengths of three commercial veneering porcelains to experimental cast titanium-chromium (Ti-Cr) alloy and commercially pure titanium (cp-Ti) via three-point bending test. After the bending test, the fractured specimens were analyzed using an electron probe microanalyzer (EPMA). The Ti-Cr specimens showed lower bond strengths than the cp-Ti specimens, irrespective of the layering porcelain material; however, all the strengths exceeded the minimum requirement of ISO 9693-1:2012 (>25 MPa). EPMA revealed that titanium and/or chromium elements were detected on the debonded porcelain surface of the Ti-Cr and cp-Ti specimens in the case of the higher bond strength. Contrastingly, the residual porcelain was retained on the metallic surface in the case of the lower bond strength. Although porcelain bonding to the titanium alloy is influenced by porcelain type, the Ti-Cr alloy could be feasible for porcelain-fused-to-metal restorations. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effect of microslits formed by Nd:YVO4 laser beam machining on the bond strength between two types of zirconia, yttria-partially stabilized zirconia (Y-TZP) and ceria-partially stabilized zirconia/alumina nanocomposite (Ce-TZP/A), and porcelain or two types of resin. Zirconia disks were divided into three groups: 1) non-treated (NT); 2) blasted with alumina particles (AB); 3) microslits fabricated on a zirconia surface by laser beam machining (MS). After veneering porcelain or resins on zirconia specimens, halves of the resin specimens were thermocycled up to 20,000 cycles. The shear bond strength between porcelain and both types of zirconia was not improved by the microslits. Before and after thermocycling, the bond strength between an indirect composite resin or acrylic resin and Y-TZP with microslits was the highest. It was concluded that the microslits on Y-TZP enabled micromechanical interlocking and improved the bond strength and durability of the resins. [ABSTRACT FROM AUTHOR]

This study evaluated shear bond strengths of two gingiva-colored layering resin composites to zirconia frameworks coated with feldspathic porcelain. Airborne-particle abraded porcelain-coated zirconia disks were treated with one of the following primers: Clearfil Photo Bond, Clearfil Photo Bond with Clearfil Porcelain Bond Activator (CPB+Activator), Estenia Opaque Primer, Porcelain Liner M Liquid B (PLB), or no primer. A light-polymerizing (CER) or a photo/heat-polymerizing gingiva-colored indirect resin composite (EST) was bonded to the porcelain-coated zirconia disks in each group (n=11). Shear bond strength was measured. For both CER and EST specimens, bond strengths in CPB+Act group were significantly higher than those in the other groups. In all priming groups, bond strength was significantly higher for EST specimens than for CER specimens. Combined application of a phosphate monomer and silane enhanced initial bond strength of light-polymerized and photo/heat-polymerized gingiva-colored layering resin composites to porcelain-coated zirconia ceramics. [ABSTRACT FROM AUTHOR]

In this study, we investigated the effect of frame design on the fracture strength of a zirconia crown and porcelain-faced crown, with the aim of clinically applying a zirconia crown fabricated using computer-aided design and manufacturing. The results showed that the fracture strengths were 645.9 MPa with Frame Design 1, 759.5 MPa with Frame Design 2, and 989.7 MPa with Frame Design 3, suggesting that the fracture strength improved depending upon the frame design. The above information suggests that it is necessary for the zirconia crown frame form to have an occlusal surface table where the crown design has a reduced outer diameter, instead of using the conventional form of covering the abutment tooth with a thickness of 0.5 mm. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the mold-enclosed shear bond strength (ME-SBS) of zirconia to veneering porcelain with different surface treatments. Colored or uncolored zirconia coupons were either highly polished or airborne-particle abraded. The specimens were divided into groups with/without application of liner. Veneering porcelain was fired into an alumina ring mold on the zirconia coupons. The assembled specimens were subjected to the ME-SBS test. The mean ME-SBS for groups ranged from 7-10 MPa with no significant difference (p>0.05). A three-way ANOVA showed that coloring and surface roughening of the zirconia specimen had no significant influence on the ME-SBS value, but liner application exhibited a significant effect with a minor decrease in the MESBS (p=0.049). Surface treatments (coloring, airborne-particle abrasion, and liner application) were found to not cause a significant increase to the zirconia-porcelain bond strength. The application of zirconia liner had a slight negative influence on the ME-SBS results. [ABSTRACT FROM AUTHOR]

The torsional fracture strength at the interface between a base plate and veneering material was evaluated for three kinds of veneered restoration: porcelain fused to zirconia (PFZ), porcelain fused to metal (PFM), and composite resin veneered metal (CRVM). The metal and zirconia base plate (30×4×0.4 mm) were prepared and these plates were veneered as test specimens using each material to a total thickness of 1.2 mm. Torsional force was applied to each specimen using a rotational speed of 1.0 deg/min until the veneering material underwent fracture or exfoliation. The torsional fracture values were measured and the data were statistically analyzed using one-way ANOVA. The torsional fracture strength for PFZ, PFM, and CRVM was 3.0, 3.1, and 11.1 N•cm, respectively. [ABSTRACT FROM AUTHOR]

To determine the effect of titanium (Ti) surface modification by ultraviolet irradiation (UVI) on the bond strength between Ti and porcelain. Grade 2 Ti plates were allotted to five groups: sandblasted (SA), 15 min UVI (UV), SA+5 min UVI (SA+UV5), SA+10 min UVI (SA+UV10), and SA+15 min UVI (SA+UV15). After surface treatment, porcelain was added. A precious metal (MC) was used for comparison with Ti. The effects of 24-h storage at room temperature versus thermal cycling only at 5 and 55°C in water were evaluated. Subsequently, the tensile strength of each sample was tested. Data were analyzed using one-way analysis of variance and the Tukey test. In both the room temperature and thermal cycling groups, the MC and SA+15 min UVI samples showed significantly greater bond strengths than the other samples (p<0.05). UVI processing efficiently increases the bond strength between porcelain and the Ti surface. [ABSTRACT FROM AUTHOR]

The objectives were to analyze the oxide layer generated between titanium and porcelain during firing and compare it in different manufacturing techniques: cast, milled and EBM-technique. Seventy two specimens were manufactured, subdivided according to surface treatment: time of passivation (P) and no time of passivation (NP) before porcelain firing. Specimens from each group were analyzed with scanning electron microscopy: one only fired once, and one subjected to six firings. Remaining specimens were subjected to shear bond strength test. The EBM-produced NP-group had highest mean value (25.0 MPa) and the milled P-group showed lowest mean value (18.5 MPa) when all factors were compared. No significant difference was detected according to time of passivation. SEM showed consistent and well-defined boundary between the different layers. Time of passivation and impact on oxide growth was not detected. The bond strength of porcelain to milled titanium is lower when compared to cast titanium and EBM-produced titanium. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate that heat treatments with different numbers applied to superstructure porcelain whether effects microstructure and mechanical properties of lithium disilicate ceramic (LDC). Eighty disc-shaped specimens were fabricated from IPS e.max Press. Specimens were fired at heating values of porcelain in different numbers and divided four groups (n=5). Initial Vickers hardness were measured and X-ray diffraction (XRD) analysis was performed. Different surface treatment were applied and then Vickers hardness, surface roughness and environmental scanning electron microscopy (ESEM) analysis were performed. Data were analyzed with Varyans analysis and Tukey HSD test (α=0.05). Initial hardness among groups was no significant different (p>0.05), but hardness and surface roughness after surface treatments were significant different (p<0.05). Lithium disilicate (LD) peaks decrease depended on firing numbers. ESEM observations showed that firing number and surface treatments effect microstructure of LDC. Increasing firing numbers and surface treatments effect the microstructure of LDC. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the effects of ceramic microbeads on the bond strength between resin and zirconia. Microbeads made of zirconia (TZ) and zircon (ZS) were treated with and without hydrofluoric acid (HF). The microbeads were sintered to zirconia disks using intermediate feldspathic porcelains. Two control groups, NB (without microbeads) and AS (without porcelain and microbeads), were also prepared. All specimens were treated with a phosphate primer and veneered with a light-curing resin composite. The 24-h shear bond strengths were determined and analyzed by the Tukey-Kramer test (α=0.05, n=10). The TZ-HF specimen exhibited the highest bond strength, followed by TZ, ZS-HF, ZS, AS, and NB. Scanning electron microscopy observations revealed that the TZ-HF specimen had a complicated debonded surface, and it included microconcavities where the microbeads were detached. Sintering etched zirconia beads onto a zirconia framework with feldspathic porcelains is useful for bonding layered resin composite materials.

The aim of this study was to evaluate the shear bond strength of porcelain fusing to titanium and the effects of surface treatment on surface structure of titanium. In the shear bond strength test, titanium surface treatments were: conventional, silica-coating without bonding agent, and silica-coating with bonding agent. Titanium surface treatments for analysis by the atomic force microscope (AFM) were: polishing, alumina sandblasting and silica-coating. The shear bond strength value of silica-coating with bonding agent group showed significantly higher than that of other groups. In AFM observation results, regular foamy structure which is effective for wetting was only observed in silica-coating. Therefore, this structure might indicate silicon. Silica-coating renders forms a nanoscopic regular foamy structure, involved in superhydrophilicity, to titanium surface, which is markedly different from the irregular surface generated by alumina sandblasting. [ABSTRACT FROM AUTHOR]

This study aims to investigate the effectiveness of monolithic translucent TZP with different colors and porcelain-layered TZP by evaluating their colors and strengths. Different mixing ratios of Zpex to Zpex-Yellow as translucent TZP, conventional opaque TZP (TZ-3YB-E) (Tosoh, Tokyo) as a control, and veneering porcelain (CERABIEN ZR, body porcelain, Noritake, Tokyo) with shade A3 as a typical shade. Disk-shaped specimens of 13 mm diameter and 1.5 mm thickness were prepared. These specimens were observed under reflected and transmitted light, and the translucency parameter (TP) values were measured. Strength was also evaluated with flexural strength in a biaxial bending test. The TP values of the monolithic TZP, Zpex100>Zpex70>Zpex50>TZ3YB, were larger in this order. The flexural strength of all the monolithic TZP showed approximately 1,000 MPa. It is suggested that colored translucent TZP is clinically useful when used as monolithic restorations. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the effect of zirconia core thickness on the biaxial flexural strength values of zirconia-porcelain bilayered discs. A total of 60 discs with 0.3, 0.4, and 0.5 mm thickness were obtained from a fully sintered zirconia block. A 1.5-mm thick layer of veneer porcelain was fired on the zirconia specimens and biaxial flexural strength tests were performed on the bilayered discs. In each group, the loading surface was the veneer porcelain in half of the specimens (core in tension) and the zirconia core surface in the other half (core in compression). The zirconia core thickness had no effect on the biaxial flexural strength of zirconiaporcelain bilayered discs when the core was in tension (p>0.05). Whereas, when the core was in compression, an increase in the zirconia core thickness resulted in an increase in the biaxial flexural strength (p<0.05). [ABSTRACT FROM AUTHOR]

The wear performances of bovine tooth enamel (BTE) against translucent tetragonal zirconia polycrystals (TZP) compared to that of feldspar porcelain and the influence of surface treatments of translucent TZP were investigated by the two-body wear test. Translucent TZP and feldspar porcelain were used as hemisphere abrader specimens with a radius of curvature of 5 mm; flat BTE surfaces were used as substrate specimens. The cross-sectional area of the worn surfaces of the substrates and the wear volume of the antagonist abraders were measured. Surface roughness, hardness and coefficient of friction as well as SEM observations and EPMA analyses were also performed to investigate the underlying mechanism of wear. The results suggested that BTE is less susceptible to wear when translucent TZP is used as the antagonist in contrast to the use of feldspar porcelain, and that surface treatment of the TZP abraders significantly influenced the wear of BTE substrates. [ABSTRACT FROM AUTHOR]

Three commercially available porcelains bonded to titanium were evaluated to determine the weakest zone of the titanium-porcelain bonding structures. Tensile bond tests were performed for these specimens (NO, DU, and VI) and for Ni-Cr alloy-porcelain bonding samples that served as controls. The maximum bond strengths between porcelain and titanium and the Ni-Cr alloy subjected to different metal surface treatments were compared. Sand blasting effectively increased bond strengths in titanium-porcelain bonding materials. No statistically significant differences in the maximum bond strengths were found between the NO sample and a control; however, sample NO exhibited greater maximum bond strength than DU and VI samples. The bond strengths increased with increasing area fractions of porcelain failure on fracture surfaces. The weakest zones were investigated based on the oxygen chemical states determined by electron spectroscopy for chemical analysis, which include bridging oxygen (Si-O-Si), nonbridging oxygen (Si-O-M+), and titanium oxide (O2-) states. We concluded that the titanium oxide layer is the weakest zone of titanium-porcelain bonding structures. [ABSTRACT FROM AUTHOR]

This study evaluated fracture load of single-tooth, implant-supported, zirconia-based, porcelain- and indirect composite-layered restorations after artificial aging. Forty-four zirconia-based molar restorations were fabricated on implant abutments and divided into four groups, namely, zirconia-based all-ceramic restorations (ZAC group) and three types of zirconia-based composite-layered restorations (ZIC-P, ZIC-E, and ZIC groups). Before layering an indirect composite material, the zirconia copings in the ZIC-P and ZIC-E groups were primed with Clearfil Photo Bond and Estenia Opaque Primer, respectively. All restorations were cemented on the abutments with glass-ionomer cement and then subjected to thermal cycling and cyclic loading. All specimens survived thermal cycling and cyclic loading. The fracture load of the ZIC-P group (2.72 kN) was not significantly different from that of the ZAC group (3.05 kN). The fracture load of the zirconia-based composite-layered restoration primed with Clearfil Photo Bond (ZIC-P) was comparable to that of the zirconia-based all-ceramic restoration (ZAC) after artificial aging. [ABSTRACT FROM AUTHOR]

The surface of a ceria-stabilized tetragonal zirconia polycrystal (Ce-TZP/A12O3) nanocomposite was sandblasted by alumina particles and veneered with feldspathic porcelain via a conventional condensation method. The part of each specimen containing the interface layer was sliced to ultrathin sections with an argon ion sheer, and these shced sections were observed using high-resolution transmission electron microscopy (HRTEM). For both interfaces, Ce-TZP/porcelain and A12O3/porcelain, no transition layers due to abrupt changes in atomic distributions were observed. Besides, the porcelain layers of both interfaces consisted of homogeneous amorphous phases. These results suggested that both Ce-TZP and A12O3 could be directly bonded to porcelain by Van der Waals forces arising from the close contact between them. [ABSTRACT FROM AUTHOR]

The purpose of this study is to investigate the fit of zirconia cores and all-ceramic crowns prepared with different cervical margin designs. The radius of curvature between the axial wall and the occlusal surface was set to 1 mm in an abutment using the cervical shoulder marginal design (S) and to 0.2 and 0.5 mm in abutments with round shoulders (0.2RS and 0.5RS, respectively). The internal gaps of the cores were 45-138 pm (S), 41-141 pm (0.2RS), and 43-133 pm (0.5RS). The internal gaps of the all-ceramic crowns were 40-115 pm (S), 45-113 pm (0.2RS), and 42-126 pm (0.5RS). There were no significant differences in one-way ANOVA for any region in any marginal design before and after firing the porcelain. The marginal gaps between the all-ceramic crowns and dies were 27±25 (S), 30±29 (0.2RS), and 24±27 pm (0.5RS), again with no significant differences in one-way ANOVA. [ABSTRACT FROM AUTHOR]

The purpose of the present study is to examine the relationship between the supportive designs of proximal region of zirconia framework on the fracture load. The zircoma frameworks with four different supportive designs on the proximal region were fabricated and classified with their radiuses of curvature (R): R=0.5 mm, R=1.0 mm, R=1.5 mm, and R=2.0 mm. The zircoma frameworks were conditioned with sandblast and veneering porcelain was fired. Subsequently, fracture tests were performed at 3 different load points: right above the lowest point of the boundary between veneering porcelain and zirconia framework; 0.5 mm inside from right above point; and 0.5mm outside from right above point. The fracture load increased with an increase in the radius of curvature of supportive design when loading was applied from above and inside. This suggested that supportive design influenced the fracture load. [ABSTRACT FROM AUTHOR]

The purpose of this study was to clarify the effect of silver nanoparticles on the behavior of subcritical crack growth (SCG) in dental porcelains. Prior to occurrence of fast fracture in dental porcelains, SCG occurs and leads to strength degradation over time. SCG in dental porcelains can be characterized by the stress corrosion susceptibility coefficient, n. A higher n value means a higher resistance to SCG. In this study, porcelain disks were prepared by mixing a commercial dental porcelain powder with different concentrations of silver nanoparticles, and then air-dried and fired according to manufacturer's instructions. Stress corrosion susceptibility coefficients of powder compacts were determined using a post-indentation method. A Vickers indenter was applied to the porcelain surface, and lengths of median cracks were measured at fixed time intervals over a 24-h period to calculate n. Addition of silver nanoparticles significantly increased the stress corrosion susceptibility coefficient of dental porcelain. [ABSTRACT FROM AUTHOR]

This study investigated the bonding of dental porcelain to non-cast Ti surface with different treatments. Mechanically ground non-cast Ti strips, simulating surface conditions produced by CAD/CAM, were AL203-sandblasted, then subjected to different surface treatments, including immersion in HN03-containing acid, NaOH-containing alkaline, and NaOH-containing alkaline then HN03-containing acid. Ti-porcelain specimens preparations and their bend strength measurements were based on ISO 9693. Ti surface treatment changed not only surface roughness but also surface chemistry, leading to influence on bond strength. Bond strengths of all Ti-porcelain groups were higher than ISO 9693 minimum requirement. The sandblasted/acid-treated Ti surface showed the highest bond strength (34.60 MPa) with porcelain; no significant difference in bond strength (27.92-29.63 MPa) was found among other Ti-porcelain groups. All Ti-porcelain specimens showed adhesive bond failure. Bonding between non-cast Ti and dental porcelain was strengthened by a simple and practical sandblasting/acid-etching treatment of the Ti surface prior to porcelain sintering. [ABSTRACT FROM AUTHOR]

The ability of staining slurries containing ailver and/or potassium compounds to enhance the mechanical properties of a leucite-reinforced glass ceramic (IPS Empress CAD) was investigated by measuring the Vickers hardness, median crack length, toughness, and compressive residual stress of specimens. A staining slurry containing potassium ions was found to increase the toughness of IPS specimens more than a staining slurry containing only silver ions when applied prior to sintering. None of the staining slurries produced any color changes. Thus, the results obtained in this study demonstrate that staining slurries increase the Vickers hardness and the fracture toughness of the surface and subsurface regions of all-ceramic IPS blocks fabricated by a CAD/CAM system without sacrificing their aesthetics. [ABSTRACT FROM AUTHOR]

Several studies have investigated toughening porcelain that is layered over a frame or a core. The introduction of residual compressive Stress to the surface of porcelain has been shown to be effective to strengthen it. In the present study, nanoparticles of precious metals of silver and platinum (rather than non-precious metals) were used to evaluate if they could increase the fracture resistance of porcelain. The addition of silver and platinum nanoparticles was found to improve the mechanical properties of porcelain since it increased both the Young's modulus and the fracture toughness of commercial porcelain. [ABSTRACT FROM AUTHOR]

In all-ceramic restorations involving a zirconia framework, surface treatment of the zirconia surface is required to enhance bonding strength with the veneering ceramics and thus prevent chipping. The purpose of the present study was to investigate the influence of surface roughness and heat treatment of the zirconia and use of liner porcelain on bond strength between veneering ceramics and a zirconia framework. Debonding/crack-initiation strength (tb) was determined according to ISO 9693. No significant difference was observed among conditions, except with use of a liner under heat treatment, which yielded a tb of 26.0±2.9-28.9±1.7 MPa. Electron probe microanalysis revealed that components of the veneering ceramics remained on the zirconia surface after debonding, suggesting that fractures occur in the veneering ceramics and that improving the strength of the veneering ceramics themselves might increase bond strength. [ABSTRACT FROM AUTHOR]

A newly designed, light-curing adhesive was investigated for its bonding effectiveness to porcelain, alumina, zirconia, Au, Au alloy, Ag alloy, Au-Ag-Pd alloy, and Ni-Cr alloy. Four experimental adhesives were prepared using varying contents of the following: a silane coupling agent [3-methacryloyloxypropyltriethoxysilane (3-MPTES)], acidic adhesive monomers [6-methacryloyloxyhexyl phosphonoacetate(6-MHPA), G-methacryloyloxyhexyl3.phosphonopropionate(6~MHpp)and4methacryloy1oxyethoxycarbonylphthaljc acid (4-MET)], and dithiooctanoate monomers [6-methacryloyloxyhexyl 6,8-dithiooctanoate (6-MHDT) and lO-methacryloyloxydecyl 6,8-dithiooctanoate (10-MDDT)]. After all adherend surfaces were sandblasted and applied with an experimental adhesive, shear bond strengths (SBSs) of a light-curing resin composite (Beautifil II, Shofu Inc., Kyoto, Japan) to the adherend materials after 2,000 times of thermal cycling were measured. For the experimental adhesive which contained 3-MPTES (30.0 wt%), 6-MHPA (1.0 wt%), 6-MHPP (1.0 wt%), 4-MET (1.0 wt%), 6-MHDT (0.5 wt%) and 10-MDDT (0.5 wt%), it consistently yielded the highest SBS for all adherend surfaces in the range of 20.8 (4.8)-30.3 (7.9) MPa, with no significant differences among all the adherend materials (p>O.05). Therefore, the newly designed, multi-purpose, light-curing adhesive was able to deliver high SBS to all the adherend materials tested. [ABSTRACT FROM AUTHOR]

A novel method was developed to fabricate all-ceramic restorations which comprised CAD/CAM-fabricated machinable ceramic bonded to CAD/CAM-fabricated zirconia framework using resin cement. The feasibility of this fabrication method was assessed in this study by investigating the bonding strength of a machinable ceramic to zirconia. A machinable ceramic was bonded to a zirconia plate using three kinds of resin cements: ResiCem (RE), Panavia (PA), and Multilink (ML). Conventional porcelain-fused-to-zirconia specimens were also prepared to serve as control. Shear bond strength test (SBT) and Schwickerath crack initiation test (SCT) were carried out. SBT revealed that PA (40.42 MPa) yielded a significantly higher bonding strength than RE (28.01 MPa) and ML (18.89 MPa). SCT revealed that the bonding strengths of test groups using resin cement were significantly higher than those of Control. Notably, the bonding strengths of RE and ML were above 25 MPa even after 10,000 times of thermal cycling —adequately meeting the ISO 9693 standard for metal-ceramic restorations. These results affirmed the feasibility of the novel fabrication method, in that a CAD/CAM-fabricated machinable ceramic is bonded to a CAD/CAM-fabricated zirconia framework using a resin cement. [ABSTRACT FROM AUTHOR]

This study evaluated the bond strengths between experimental Ti-20Cr-1X (X=Nb, Mo, Fe, Zr) alloys and porcelain (Duceratin). The results of this bond strength testing indicated that all the Ti-20Cr-1X alloys exceeded the lower limit value in the ISO 9693 standard for the 3-point bending test (25 MPa), and were all higher than that of commercially pure titanium (c.p. Ti). The coefficient of thermal expansion (CTE) values of all Ti-20Cr-1X alloys were higher than that of c.p. Ti, and this result of a closer match between CTEs shows the fact that the Ti-20Cr-1Mo alloy had a significantly higher bond strength than both the other Ti-20Cr-1X alloys and c.p. Ti. [ABSTRACT FROM AUTHOR]

This study investigated the influence of zirconia coping designs on the fracture load of all-ceramic crown. Four kinds of zirconia copings were designed (a: Conventional zirconia coping with flat occlusal surface: thickness of the each coping is 0.6 mm evenly, and at the cervical margin area, the coping is adjusted sharply so as to fit preparation margin, b: Conventional zirconia coping with shoulder collar of 1 mm: thickness of the each coping is 0.6 mm evenly, and there is a collar of 0.6 mm from the margin, c: Zirconia coping with following original cuspal configuration (concave): two inclined cusp planes, and at the cervical margin area, the coping is adjusted sharply so as to fit preparation margin, and d: Zirconia coping with supporting configuration on the occlusal area: supporting configuration against the occlusal force, and at the cervical margin area, the coping is adjusted sharply so as to fit preparation margin) and porcelain was fired. Vertical and lateral load were conducted until fracture. Coping design affected the fracture load; conventional uniform thickness coping design showed the lowest load (a), whereas cuspal configuration to perform even thickness of porcelain showed the highest fracture load both load directions (c). [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the shear bond strengths (SBS) of cast, machined, and laser-sintered titanium to dental porcelain. Two kinds of dental porcelains (Titankeramik and Triceram) were applied on cast (Tritan), machined (DC-Titan), and laser-sintered (EOSINT) titanium specimens (n=10). SBS test was conducted, and fracture surface analysis was also performed to determine the failure modes. Two-way ANOVA, Student's t-test, and post hoc test were used to analyze the data (p<0.05). Among the titanium specimens, the SBS values of laser-sintered titanium specimens were significantly higher than the machined and cast titanium specimens (p<0.01). Comparison of Triceram and Titankeramik veneering porcelains showed no statistically significant differences in SBS when they were applied on laser-sintered and cast titanium specimens (p>0.05). Specimens in all the test groups exhibited adhesive or combined failure, with the Titankeramik-machined titanium group exhibiting the highest adhesive failure rate (40%). Results showed that porcelain-titanium bond strengths could be improved by using the new laser sintering technique to produce titanium for prosthodontic applications. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to test the hypothesis that glazing will affect the Weibull modulus or the mean flexural strength of dental porcelain. Four groups (n = 30) of specimens were prepared from feldspathic body porcelain (Vita VMK 68). The specimens were tested in groups: original glazed condition (control), and after grinding separately with 1,000-grit, 600-grit, and 100-grit silicon carbide abrasive. A three-point flexure test was undertaken for each specimen. The flexural strength of porcelain and the Weibull modulus were then obtained using a computer program and load-to-failure data. Flexural strength decreased as surface roughness increased, and the differences were significant (p < 0.05), as determined by Tukey's multiple range test, except between the 600-grit group and the 100-grit group. The Weibull modulus of the glazed group was the largest (16.3), and the surface roughness was found to influence the Weibull modulus. [ABSTRACT FROM AUTHOR]

This study investigated the interfacial microstructure between gold-coated titanium and low-fusing porcelain. The square surfaces of cast titanium split rods were sputter-coated with gold using a sputter coater at 40 mA for 1,000 seconds. Specimens were prepared for transmission electron microscopy (TEM) by cutting and polishing two pieces of the gold-coated split-rod specimens, which were glued and embedded in Cu tubes with an epoxy adhesive. TEM observation was also conducted for the gold-coated specimens after degassing and porcelain fusing. Due to the gold coating, intermetallic compounds of Au-Ti formed under the sputtered gold layer after degassing and porcelain fusing. Ti3Au and Ti3Al layers were also observed beneath the Au-Ti intermetallic compound layer. There was good adhesion of porcelain to the Au-Ti compound and Ti oxides without any gaps or formation of a Ti-deficient intermediate layer, which is normally observed at the titanium-porcelain interface. The results of this TEM study suggested that gold-sputter-coating the cast titanium surface produced a Ti-Au intermetallic compound and suppressed the formation of a Ti-deficient intermediate layer, resulting in improved adherence between porcelain and titanium. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to evaluate the bond strength and durability of four bonding systems joined to a pre-fabricated porcelain material (Vita Celay Blanks). Two sizes of porcelain block were bonded with one of the following systems: (1) Clapearl Bonding Agent and Clapearl DC; (2) Imperva Porcelain Primer and Imperva Dual; (3) Monobond S and Variolink II; or (4) Tokuso Ceramics Primer and Bistite II. Shear bond strength was measured after 24-hour immersion in water and after subsequent thermocycling. The average pre- and post-thermocycling bond strengths in MPa (n=8) were: 52.5 and 42.5 for bonding system (1), 47.7 and 32.8 for (2), 55.0 and 48.8 for (3), and 51.5 and 25.6 for (4). Although prethermocycling results were not statistically different from each other, Group (3) exhibited the greatest strength after thermocycling. [ABSTRACT FROM AUTHOR]

This study evaluated bond strengths of three commercial veneering porcelains to experimental cast titanium-chromium (Ti-Cr) alloy and commercially pure titanium (cp-Ti) via three-point bending test. After the bending test, the fractured specimens were analyzed using an electron probe microanalyzer (EPMA). The Ti-Cr specimens showed lower bond strengths than the cp-Ti specimens, irrespective of the layering porcelain material; however, all the strengths exceeded the minimum requirement of ISO 9693-1:2012 (>25 MPa). EPMA revealed that titanium and/or chromium elements were detected on the debonded porcelain surface of the Ti-Cr and cp-Ti specimens in the case of the higher bond strength. Contrastingly, the residual porcelain was retained on the metallic surface in the case of the lower bond strength. Although porcelain bonding to the titanium alloy is influenced by porcelain type, the Ti-Cr alloy could be feasible for porcelain-fused-to-metal restorations.

The aim of this study was to investigate the effect of microslits formed by Nd:YVO 4 laser beam machining on the bond strength between two types of zirconia, yttria-partially stabilized zirconia (Y-TZP) and ceria-partially stabilized zirconia/alumina nanocomposite (Ce-TZP/A), and porcelain or two types of resin. Zirconia disks were divided into three groups: 1) non-treated (NT); 2) blasted with alumina particles (AB); 3) microslits fabricated on a zirconia surface by laser beam machining (MS). After veneering porcelain or resins on zirconia specimens, halves of the resin specimens were thermocycled up to 20,000 cycles. The shear bond strength between porcelain and both types of zirconia was not improved by the microslits. Before and after thermocycling, the bond strength between an indirect composite resin or acrylic resin and Y-TZP with microslits was the highest. It was concluded that the microslits on Y-TZP enabled micromechanical interlocking and improved the bond strength and durability of the resins.

In this study, we investigated the effect of frame design on the fracture strength of a zirconia crown and porcelain-faced crown, with the aim of clinically applying a zirconia crown fabricated using computer-aided design and manufacturing. The results showed that the fracture strengths were 645.9 MPa with Frame Design 1, 759.5 MPa with Frame Design 2, and 989.7 MPa with Frame Design 3, suggesting that the fracture strength improved depending upon the frame design. The above information suggests that it is necessary for the zirconia crown frame form to have an occlusal surface table where the crown design has a reduced outer diameter, instead of using the conventional form of covering the abutment tooth with a thickness of 0.5 mm.

To determine the effect of titanium (Ti) surface modification by ultraviolet irradiation (UVI) on the bond strength between Ti and porcelain. Grade 2 Ti plates were allotted to five groups: sandblasted (SA), 15 min UVI (UV), SA+5 min UVI (SA+UV5), SA+10 min UVI (SA+UV10), and SA+15 min UVI (SA+UV15). After surface treatment, porcelain was added. A precious metal (MC) was used for comparison with Ti. The effects of 24-h storage at room temperature versus thermal cycling only at 5 and 55°C in water were evaluated. Subsequently, the tensile strength of each sample was tested. Data were analyzed using one-way analysis of variance and the Tukey test. In both the room temperature and thermal cycling groups, the MC and SA+15 min UVI samples showed significantly greater bond strengths than the other samples (p<0.05). UVI processing efficiently increases the bond strength between porcelain and the Ti surface.