Glass-infiltrated Zirconia Research Articles

Surface modification of dental zirconia implants with a low infiltration temperature glass.

The glass infiltration technique was employed for surface modification of zirconia implants in this study. The prepared glass-infiltrated zirconia with low infiltrating temperature showed excellent mechanical properties and enough infiltrating layer. The zirconia substrate was pre-sintered at 1,200°C and the glass infiltration depth reached 400 μm after infiltrating at 1,200°C for 10 h. The infiltrating glass has good wetting ability, thermal expansion match and good chemical compatibility with the zirconia substrate. Indentation fracture toughness and flexural strength of the dense sintered glass-infiltrated zirconia composite are respectively 5.37±0.45 MPa•m1/2 and 841.03±89.31 MPa. Its elasticity modulus is 163.99±7.6 GPa and has about 500 μm infiltrating layer. The glass-infiltrated zirconia can be acid etched to a medium roughness (1.29±0.09 μm) with a flexural strength of 823.65±87.46 MPa, which promotes cell proliferation and has potential for dental implants.

Infiltration OF 5Y-PSZ with thermally compatible glass: Strength, microstructure and failure mode analyses

This study set out to develop a thermally compatible glass to be infiltrated into zirconia partially stabilized by yttrium oxide (5Y-PSZ), to characterize it, and to evaluate its structural reliability and mechanical behavior. 5Y-PSZ zirconia discs (N = 90), dimensions 1.5 mm × 15 mm were produced, polished with #600 alumina oxide and #1200 silicon carbide sandpaper in a polisher. Three groups of 5Y-PSZ discs were assigned (n = 30): Zctrl: as sintered zirconia, Zinf-comp: glass-infiltrated zirconia on the occlusal surface, and sintered, and Zinf-tens: glass-infiltrated zirconia on the cementing surface and sintered; for biaxial flexural strength testing (ISO 6872:2015). A gel was synthesized via the sol-gel method and applied to the ceramic surface. Mechanical assay data (MPa) were evaluated via Weibull analysis (α = 5%) and specimens via X-Ray Diffractometry (XRD), Scanning Electron Microscopy (SEM), and fractographic analysis. The Zinf-tens group showed a characteristic strength of 824 MPa and m = 9.9; Zinf-comp 613 MPa and m = 10.2; Zctrl 534 MPa and m = 8; all groups differed statistically (σ0). However, they were similar in structural homogeneity (m). XRD showed 20–50 μm of infiltration, which means dissolution of part of the yttrium and reduction in the size of the cubic grains. In addition, the Zinf-tens group presented a failure origin from inside the material. The developed glass infiltrated into zirconia partially stabilized by yttrium oxide, increasing its characteristic strength and structural homogeneity by reducing surface defects and changing the failure mode.

Silica infiltration on translucent zirconia restorations: Effects on the antagonist wear and survivability.

To assess potential antagonist wear and survival probability of silica-infiltrated zirconia compared to glass-graded, glazed, and polished zirconia. Table top restorations made of 3Y-TZP (3Y), 5Y-PSZ (5Y), and lithium disilicate (LD) were bonded onto epoxy resin preparations. Each zirconia was divided into five groups according to the surface treatment: polishing; glaze; polishing-glaze; glass infiltration; and silica infiltration. The LD restorations received a glaze layer. Specimens were subjected to sliding fatigue wear using a steatite antagonist (1.25×106 cycles, 200N). The presence of cracks, fractures, and/or debonding was checked every one/third of the total number of cycles was completed. Roughness, microstructural, Scanning electron microscopy, wear and residual stress analyses were conducted. Kaplan-Meier, Mantel-Cox (log-rank) and ANOVA tests were performed for statistical analyses. The survival probability was different among the groups. Silica infiltration and polishing-glaze led to lower volume loss than glaze and glass-infiltration. Difference was observed for roughness among the zirconia and surface treatment, while lithium disilicate presented similar roughness compared to both glazed zirconia. Scanning electron microscopy revealed the removal of the surface treatment after sliding fatigue wear in all groups. Compressive stress was detected on 3Y surfaces, while tensile stress was observed on 5Y. 3Y and 5Y zirconia behaved similarly regarding antagonist wear, presenting higher antagonist wear than the glass ceramic. Silica-infiltrated and polished-glazed zirconia produced lower antagonist volume loss than glazed and glass-infiltrated zirconia. Silica-infiltrated 3Y and lithium disilicate restorations were the only groups to show survival probabilities lower than 85%.

Zirconia gradation and thermal expansion compatibility between infiltration glass and antimicrobial glass

This study evaluated an infiltration glass over zirconia in order to form a graded layer with thermal expansion coefficient compatibility and antimicrobial capacity. 210 discs of 3Y-TZP were polished and divided into groups: YZ sintered (Sintered), YZ glazed (Glaze), YZ + Ag 5% (Ag 5%), YZ + Ag 4% (Ag 4%), YZ glass infiltrated (INF.), YZ glass infiltrated + Ag 5% (INF. + Ag 5%) and YZ glass infiltrated + Ag 4% (INF. + Ag 4%). Analyzes of biaxial flexural strength, X-ray diffraction (XRD), EDS, translucency, scanning electron microscopy (SEM) and fractographic were performed. The biofilm was quantified by counting the colony forming units (CFU/mL) of S. mutans. Strength values (MPa), translucency and CFU data were analyzed by one-way ANOVA and Tukey's test (α = 0.05). Weibull analysis was performed to calculate the material's modulus (m) and characteristic strength (95% CI). Infiltrated zirconia glass (INF.: 1149.7; INF. + Ag 4%: 928.2; INF. + Ag 5%: 791.5), sintered (819.0) or glazed (790.8) showed higher flexural strength (MPa) than silver-doped soda-lime glass zirconia without infiltration glass (Ag 5%: 612.1; Ag 4%: 519.2). Diffractograms showed combeite crystals in INF. + Ag 4%/5%. EDS analysis of Ag 5% group showed the higher quantity of silver when compared to INF. + Ag 5% group. Silver-doped soda-lime glass did not affect the translucency, while infiltration glass decreased the values. SEM showed irregularities on the surface of the silver-doped soda-lime glass groups and a smooth surface on the glass and glaze groups. Fracture origin of all groups was in the glaze layer and silver-doped soda-lime glass, while it was inside the zirconia in the INF. group. Lowest colony growth was observed in the Ag 5%. Glass-infiltrated zirconia showed greater strength, while Ag 5% presented greater antimicrobial capacity. The application of silver-doped soda-lime glass did not influence zirconia translucency, while glass infiltration decreased it.

Effects of surface modification techniques on zirconia substrates and their effect on bonding to dual cure resin cement - An in- vitro study.

This study aims to evaluate the effect of different surface treatments of monolithic zirconia on the bond strength of resin to zirconia and, to explore alternative methods to improve this bonding. In-Vitro study. Fifty rectangular sintered blocks of Yttria-stabilized Tetragonal Zirconia Polycrystal ceramics of dimensions were milled and sintered. These specimens were further divided into five groups (control, air abrasion, etching with primer application, air abrasion with primer application and novel glass infiltrated zirconia surface group), containing 10 samples each. The specimens were analyzed for surface roughness, tensile bond strength to resin cements, and adhesive and cohesive mode of failures. ANOVA and Post-Hoc Tukey test was perform to evaluate the significant differences in the mean values of the groups. Air-abraded samples showed the highest surface roughness (4.95 ± 0.65) (P < 0.05). The group with air abrasion followed by primer application showed the highest tensile bond strength (7.12 ± 0.69) (P < 0.05). The lowest surface roughness (0.638 ± 0.8093) and tensile bond strength (2.03 ± 0.58) was seen in samples that were subjected to etchant treatment followed by application of methacryloyloxydecyl di-hydrogen phosphate (MDP) primer. The changes in comparison to the control group were statistically insignificant (P > 0.05). Except Groups A (control) and C (etchant followed by primer), all other groups showed a cohesive failure. Air abrasion of the zirconia surface with 50 μm alumina particles increases the surface roughness without damaging the surface. Air abrasion followed by MDP primer application is the recommended method of surface treatment to achieve superior bonding. Glass infiltration also showed promising results in terms of tensile bond strength.

Hybrid porous zirconia scaffolds fabricated using additive manufacturing for bone tissue engineering applications

For the formation of new bone in critical-sized bone defects, bioactive scaffolds with an interconnected porous network are necessary. Herein, we fabricated three-dimensional (3D) porous hybrid zirconia scaffolds to promote hybrid functionality, i.e., excellent mechanical properties and bioactive performance. Specifically, the 3D printed scaffolds were subjected to Zn-HA/glass composite coating on glass-infiltrated zirconia (ZC). In addition, to pertain the extracellular matrix of bone, biopolymer (alginate/gelatine) was embedded in a developed 3D construct (ZB and ZCB). A zirconia-printed scaffold (Z) group served as a control. The structural and mechanical properties of the constructed scaffolds were studied using essential characterization techniques. Furthermore, the biological performance of the designed scaffolds was tested by a sequence of in vitro cell tests, including the attachment, proliferation, and osteogenic differentiation of dental pulp cells (DPCs). The ZC and ZCB scaffolds exhibited 20% higher compression strength than the zirconia (Z) scaffolds. More importantly, the ZC constructs exhibited superior cell-adhesion, distribution, and osteogenic differentiation ability due to the synergistic effects of the composite coating. In addition, the biopolymer-embedded scaffolds (ZB, ZCB) showed an excellent biological and mechanical performance. Thus, our results suggest that the Zn-HA/glass composite-coated glass-infiltrated zirconia (ZC, ZCB) scaffolds are a dynamic approach to designing bioactive 3D scaffolds for the load-bearing bone regeneration applications.

Evaluation of the color and translucency of glass-infiltrated zirconia based on the concept of functionally graded materials

Statement of problemInfiltrated zirconia has promising mechanical properties. However, information about its optical behavior is scarce. PurposeThe purpose of this in vitro study was to evaluate the color and translucency of zirconia submitted to infiltration and aging. Material and methodsSixty zirconia disks were machined. Ten disks received no treatment (NT group), 10 disks were immersed in a coloring liquid (A2 group), and 10 disks were immersed in a fluorescent liquid (F group). The other 30 disks were submitted to the same treatments plus glass infiltration (NT+I, A2+I, and F+I groups). The coordinates L*, a*, and b* and the Y tristimulus values were obtained to calculate the color (ΔE00), lightness, chroma, and hue differences; the translucency parameter (TP); and the contrast ratio (CR) associated with the specimens. After aging in an autoclave for 4 hours (T1), new measurements were made. Two- and 3-way ANOVAs were used to analyze color differences, TP, and CR. The lightness, chroma, and hue differences were evaluated by a repeated measures ANOVA. Multiple comparisons were made with the Tukey honestly significant difference (HSD) test (α=.05). ResultsThe greatest color differences were observed in the A2+I group (11.23 ΔE00) (P<.001). Aging affected the chroma of the colored groups (P=.013 and P=.001) but did not affect their translucency (P=.347 for TP and P=.132 for CR). The greatest TP values were found in the NT and NT+I groups (2.54 and 2.34, respectively), whereas the CR was equal to or close to 1 in all groups. ConclusionsColor differences were observed in the glass-infiltrated groups. The TP and CR were affected by infiltration. Aging did not influence the optical behavior of the specimens.

Tailoring interfacial interaction through glass fusion in glass/zinc-hydroxyapatite composite coatings on glass-infiltrated zirconia

In the current study, the biocompatibility and mechanical characteristics of glass-infiltrated zirconia were improved via a simple composite coating made of Zn-doped hydroxyapatite (ZnHA) ceramic and a silicate-based glass. During thermal treatment, significant reaction and crystallisation occurred and some of the ZnHA was transformed into β-tricalcium phosphate, calcium oxide phosphate, and calcium zirconium oxide. Moreover, the glass crystallised into a sodium calcium aluminium silicate phase. The mechanical properties were investigated and the results indicated that the amount of glass in the composite and in the glass-infiltrated zirconia layer strongly affected the flexural strength and adhesion of the coating layer. The composite coatings on the glass-infiltrated zirconia displayed better mechanical properties than the pure ZnHA coating due to the newly formed crystalline phases. Murine pre-osteoblastic (MC3T3-E1) cells adhered to and spread well on the composite coating surfaces. The cell viability results revealed that the glass/ZnHA composites demonstrated a superior bioactivity of osteoblast cells compared to uncoated zirconia. These results show that the glass/ZnHA composites on the glass-infiltrated zirconia structure are suitable for use as hard tissue implant coatings due to their morphological and mechanical stability and enhanced bioactivity to pre-osteoblastic cells.

Evaluation of Acid Etching on Surface Characteristics, Strength and Biological Response of Glass-Infiltrated Zirconia.

This study evaluated the effect of acid etching on surface characteristics, flexural strength and osteoblast cell response of glass-infiltrated zirconia. Zirconia specimens were divided into six groups: untreated zirconia (Z); glass-infiltrated zirconia (ZG); glass-infiltrated and sandblasted zirconia (ZGS); glass-infiltrated, sandblasted and 5 min acid-etched zirconia (ZGS-E5); glassinfiltrated, sandblasted and 15 min acid-etched zirconia (ZGS-E15); glass-infiltrated, sandblasted and 25 min acid-etched zirconia (ZGS-E25). Surface roughness, biaxial flexural strength and MC3T3-E1 cell proliferation were evaluated. When increasing etching time, surface roughness significantly increased while flexural strength decreased. Cell proliferation rate at day 3 on group ZGS-E15 and ZGS-E25 was significantly higher than that of other groups. Surface roughness and flexural strength of glass-infiltrated zirconia can be controlled by adjusting etching time. Rough surface made by acid etching following glass infiltration significantly enhanced osteoblast cell response. Glass infiltration improved strength of zirconia but severe acid etching slightly reduced strength of zirconia.

Evaluation of the Fitness of Glass-Infiltrated Zirconia Core in Maxillary Central Incisor.

The purpose of this study was to evaluate the fitness of zirconia cores according to the amount and treated surface of glass infiltration. A maxillary right central incisor customized abutment was milled to have a 6° slope and a 1 mm deep chamfer margin and was manufactured in an intaglio mold using silicone impression material. Fifty-six stone dies were produced by injecting high strength dental stone into a mold and then zirconia cores were milled with CAD/CAM systems. The control group (Control) used non glass-infiltrated zirconia, and the experiment group was divided by one with the glass and distilled water ratio of 1:300 and the other with the ratio of 1:100. Each group was divided into subgroups by glasstreated surface: external surface infiltration, internal surface infiltration, and both surface infiltration. The zirconia cores sintered after glass infiltration were attached to the stone dies and then cut. Afterwards, the absolute marginal discrepancies and internal gaps of the buccal and lingual sides were measured. The buccal absolute marginal discrepancies and lingual internal gaps were influenced by the glass infiltration amount (p < 0.05); while fitness of zirconia core were not affected by the glasstreated surface (p > 0.05). As a result of the above experiments, the glass-infiltrated zirconia cores showed a clinically acceptable fitness, which is within 120 μm. This means that glass infiltration can be clinically used.

Evaluation of Sandblasting on Mechanical Properties and Cell Response of Bioactive Glass Infiltrated Zirconia.

This study investigated the mechanical properties and initial cell response of bioactive glass infiltrated zirconia before and after sandblasting. One hundred zirconia specimens were divided into the following four groups: untreated zirconia (ZR), sandblasted zirconia (ZS), glass infiltrated zirconia (ZG), and sandblasted glass infiltrated zirconia (ZGS). Surface roughness, biaxial flexural strength, hardness and osteoblast cells proliferation were evaluated. ZGS group showed a slight decrease in hardness. However it has improvement in flexural strength (686.2 MPa). After sandblasting, the ZGS group had the highest surface roughness (R a = 1.24 μm) with enhanced osteoblast cells response. Our results indicated that sandblasting method can improve the mechanical properties of bioactive glass infiltrated zirconia with better osteoblast cell response. This new surface is promising for zirconia dental implant application in the future.

The Effect of Glass Layer Thickness on the Shear Bond Strength Between Glass Infiltrated Zirconia and Veneering Porcelain.

This study was to investigate the various glass thicknesses on the shear bond strength between zirconia and veneering porcelain. The zirconia specimens were classified into 5 groups (n = 12). For the control group, the Y-TZP disk was sintered (G0). For the test group, the presintered zirconia disks were spin coated with different W/P ratio glass compositions. The glass thickness on the zirconia was 1 μm (G1), 4 μm (G4), 10 μm (G10), and 40 μm (G40), respectively. All specimens were build-up veneering porcelain and fired. The shear bond strength (SBS) was tested in a universal testing machine (crosshead speed = 0.5 mm/min). As the thickness of the glass decreased, the shear bond strength increased. The G1 group showed significantly higher than the control group (G0) (P < 0.05). The results suggest that the thickness of glass coating on the zirconia structure needs to be made thin for better bonding strength with veneering porcelain.

Surface Characteristics of Bioactive Glass-Infiltrated Zirconia with Different Hydrofluoric Acid Etching Conditions

The purpose of this study was to examine the surface characteristics of bioactive glass-infiltrated zirconia specimens that underwent different hydrofluoric acid (HF) etching conditions. Specimens were classified into the following six groups: Zirconia, Zirliner, Porcelain, Bioactive glass A1, Bioactive glass A2, and Bioactive glass A3. Zirliner and porcelain were applied to fully sintered zirconia followed by heat treatment. Bioactive glass was infiltrated into presintered zirconia using a spin coating method followed by complete sintering. All the specimens were acid-etched with 10% or 20% HF, and surface roughness was measured using a profiler. The surface roughness of the zirconia group was not affected by the etching time or the concentration of the acid. The roughness of the three bioactive glass groups (A1, A2, and A3) was slightly increased up until 10 minutes of etching. After 1 hour of etching, the roughness was considerably increased. The infiltrated bioactive glass and acid etching did not affect the adhesion and proliferation of osteoblasts. This study confirmed that surface roughness was affected by the infiltration material, etching time, and acid concentration. For implant surfaces, it is expected that the use of etched bioactive glass-infiltrated zirconia with micro-topographies will be similar to that of machined or sand-blasted/acid-etched (SLA) titanium.

Acid etching of glass-infiltrated zirconia and its biological response.

PURPOSEThe purpose of this study was to evaluate the influence of acid etching treatment on surface characteristics and biological response of glass-infiltrated zirconia.MATERIALS AND METHODSA hundred zirconia specimens were divided into four groups depending on surface treatments: untreated zirconia (group Z); acid-etched zirconia (group ZE); glass-infiltrated zirconia (group ZG); and glass-infiltrated and acid-etched zirconia (group ZGE). Surface roughness, surface topography, surface morphology, and Vickers hardness of specimens were evaluated. For biological response test, MC3T3-E1 cell attachment and proliferation on surface of the specimens were examined. The data were statistically analyzed using one-way ANOVA and Tukey's HSD test at a significance level of 0.05.RESULTSGroup ZGE showed the highest surface roughness (Ra = 1.54 µm) compared with other groups (P < .05). Meanwhile, the hardness of group Z was significantly higher than those of other groups (P < .05). Cell attachment and cell proliferation were significantly higher in group ZGE (P < .05).CONCLUSIONWe concluded that effective surface roughness on zirconia could be made by acid etching treatment after glass infiltration. This surface showed significantly enhanced osteoblast cell response.

Effect of Infiltration with Ferric Oxide Containing Glass on the Color and Mechanical Properties of Zirconia

This study was to examine the effects of ferric oxide contents, which is one of the components of a newly developed glass, on the color and mechanical strengths of zirconia surfaces after glass infiltration. The composition of bioactive glass contained: SiO2–Al2O3–Na2O–MgO–BaO–CaO–Nb2O5–TiO2–Fe2O3. 84 presintered zirconia discs (diameter 15 mm, height 1.2 mm) were prepared. The experimental groups were divided into 6 groups by Fe2O3 contents of 0, 1, 1.5, 2.0, 2.5 and 2.9 wt%. Non-glass infiltrated zirconia was used as a control. Bioactive glass was coated on the presintered zirconia disc by a spin coating and infiltrated into zirconia by complete sintering at 1450°C for 2 hr. The color of the specimens was measured using a digital spectrophotometer and biaxial flexural strength and fracture toughness was compared. The colors of glass infiltrated zirconia were from yellow to yellowish orange according to ferric oxides contents and those were within the range of natural teeth colors. The mechanical properties of glass infiltrated zirconia were not inferior to those of zirconia. Glass infiltration with ferric oxide into zirconia can improve the color and mechanical properties of zirconia and be applicable for dental purpose.

The effect of silane applied to glass ceramics on surface structure and bonding strength at different temperatures.

PURPOSETo evaluate the effect of various surface treatments on the surface structure and shear bond strength (SBS) of different ceramics.MATERIALS AND METHODS288 specimens (lithium-disilicate, leucite-reinforced, and glass infiltrated zirconia) were first divided into two groups according to the resin cement used, and were later divided into four groups according to the given surface treatments: G1 (hydrofluoric acid (HF)+silane), G2 (silane alone-no heat-treatment), G3 (silane alone-then dried with 60℃ heat-treatment), and G4 (silane alone-then dried with 100℃ heat-treatment). Two different adhesive luting systems were applied onto the ceramic discs in all groups. SBS (in MPa) was calculated from the failure load per bonded area (in N/mm2). Subsequently, one specimen from each group was prepared for SEM evaluation of the separated-resin–ceramic interface.RESULTSSBS values of G1 were significantly higher than those of the other groups in the lithium disilicate ceramic and leucite reinforced ceramic, and the SBS values of G4 and G1 were significantly higher than those of G2 and G3 in glass infiltrated zirconia. The three-way ANOVA revealed that the SBS values were significantly affected by the type of resin cement (P<.001). FIN ceramics had the highest rate of cohesive failure on the ceramic surfaces than other ceramic groups. AFM images showed that the surface treatment groups exhibited similar topographies, except the group treated with HF.CONCLUSIONThe heat treatment was not sufficient to achieve high SBS values as compared with HF acid etching. The surface topography of ceramics was affected by surface treatments.

Effect of Different Surface Treatments on Porcelain-Resin Bond Strength.

The aim of this study was to evaluate the effects of various surface treatments on the surface structure and shear bond strength (SBS) of different ceramics. A total of 192 disk-shaped cores were prepared using two all-ceramic systems, of which 168 were submitted to SBS tests, and 24 were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The ceramics used were IPS Empress e.max (EX) lithium glass-ceramic and Vita In-Ceram Zirconia glass-infiltrated zirconia (ICZ). The specimens were randomly divided into seven groups (n = 12) on the basis of the surface treatment used: control; SB-sandblasting with 50 μm Al2 O3 particles; CJ-chairside silica coating with 30 μm SiO2 particles and silanization (Clearfil Porcelain Bond Activator); HF-etching in 5% hydrofluoric acid and silanization; ER-etching with an Er:YAG laser (10 W); ND-Nd:YAG laser etching (0.8 W); and FS-etching with a femtosecond laser (860 mW). A luting cement (Clearfil Esthetic) was photopolymerized on each treated ceramic disk. After subjecting the specimens to thermocycling (1000 cycles, 5°C to 55°C), SBS tests were performed using a universal testing machine. The data were analyzed with two-way ANOVA and Tukey's tests using a significance limit of 5%. Among the EX ceramics, the CJ (29.10 MPa) and HF (26.07 MPa) specimens had statistically higher SBS values. For the ICZ ceramics, the highest value (28.08 MPa) was obtained for the CJ specimens. Silanization after coating with silica improves the bond strengths of both EX and ICZ specimens, while HF etching is favorable only for the EX specimens.

Ten-year clinical outcome of three-unit posterior FDPs made from a glass-infiltrated zirconia reinforced alumina ceramic (In-Ceram Zirconia)

ObjectivesTo evaluate the long-term survival and complication rates of posterior three-unit fixed dental prostheses (FDPs) fabricated from a glass-infiltrated zirconia reinforced alumina ceramic (In-Ceram Zirconia). MethodsFifty-eight patients received 65 FDPs. Twelve FDPs replaced the second premolar (8 in the maxilla, 4 in the mandible), and 53 replaced the first molar (19 in the maxilla, 34 in the mandible). The In-Ceram Zirconia ceramic frameworks were designed and milled using the Cerec CAD/CAM system. The minimum dimension of the proximal connectors of the frameworks was 12mm2 and 16mm2 for premolars and molars, respectively. After milling and glass infiltration, the frameworks were veneered with a feldspathic ceramic. All FDPs were cemented with glass-ionomer cement. The patients were recalled 6–12 months after placement, and then annually. Kaplan–Meier analysis was used to calculate the survival and complication rates of the FDPs. ResultsThe mean observation time was 9.7 years. Six patients with 6 FDPs were regarded as dropouts. Using the Kaplan–Meier method the 10-year cumulative survival rate was 93.6%. In a worst-case scenario, in which the 6 missing FDPs are considered as failed, the 10-year survival rate would be 84.6%. ConclusionThree-unit posterior FDPs made from In-Ceram Zirconia presented a 10-year survival rate similar to that reported for conventional FDPs. However more technical and biological complications were reported. Clinical significanceThree-unit posterior FDP made from In-Ceram Zirconia may be a viable treatment modality, taking the strict adherence to the manufacturer's recommendations into consideration.

Fracture strength of borosilicate glass melt infiltrated zirconia 3-unit bridge

This study examined the fracture strength of 3-unit all-ceramic zirconia bridges treated with a melt-infiltration process of borosilicate glass. The zirconia specimens were milled with presintered yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) blocks. Before veneering the porcelain, borosilicate glass was infiltrated into the zirconia at 1,100°C for 1 hr. A 3-point flexural test was carried out at crosshead speed of 0.1 mm/min. The fracture surface and interface between the zirconia and veneer porcelain were observed by scanning electron microscopy. The fracture strength of the Y-TZP specimens was increased significantly by the melt-infiltration process of borosilicate glass (P < 0.05). The bond strength of the porcelain on zirconia was also improved significantly by meltinfiltration process of borosilicate glass (P < 0.05). The resistance to the initial chipping of the veneered porcelain in the 3-unit allceramic zirconia bridges was increased significantly by melt-infiltration process of borosilicate glass (P < 0.05). According to the microscopic observations of the fracture surface of porcelain, the glass-infiltrated zirconia group showed a rough fracture surface, whereas the sintered zirconia group showed a smooth fracture surface containing many pores.

Chipping Resistance of Graded Zirconia Ceramics for Dental Crowns

A serious drawback of veneering porcelains is a pronounced susceptibility to chipping. Glass-infiltrated dense zirconia structures can now be produced with esthetic quality, making them an attractive alternative. In this study, we examined the hypothesis that such infiltrated structures are much more chip-resistant than conventional porcelains, and at least as chip-resistant as non-infiltrated zirconia. A sharp indenter was used to produce chips in flat and anatomically correct glass-infiltrated zirconia crown materials, and critical loads were measured as a function of distance from the specimen edge (flat) or side wall (crown). Control data were obtained on zirconia specimens without infiltration and on crowns veneered with porcelains. The results confirmed that the resistance to chipping in graded zirconia is more than 4 times higher than that of porcelain-veneered zirconia and is at least as high as that of non-veneered zirconia.