IPS Empress Research Articles

Effect of machining damage on the surface roughness and flexural strength of CAD-CAM materials

Computer-aided design and computer-aided manufacturing (CAD-CAM) materials are available for different types of restorations. However, the longevity of the material is affected by chipping, milling damage, flexural strength, and surface roughness, and a standard edge chipping test or standardized measurements are unavailable for monitoring edge chipping of rotary instrument-milled materials. The purpose of this in vitro study was to analyze the surface roughness and edge chipping of different CAD-CAM diamond rotary instrument-milled dental material bars, correlate the effect of machining damage with material strength, and compare the flexural strength of rotary instrument-milled and sectioned CAD-CAM blocks. Five dental CAD-CAM materials were tested: lithium disilicate glass-ceramic (IPS e.max CAD), leucite-reinforced glass-ceramic (IPS Empress CAD); feldspathic porcelain (Vitablocs Mark II); feldspar ceramic-polymer infiltrated (Enamic), and composite resin (Lava Ultimate). Rectangular bars were designed and milled for each material (n=10). The surface roughness of the bars was measured using a profilometer. All edges of 3 selected bars were analyzed with scanning electron microscopy (SEM) for the chip length, depth, and area. The 3-point bend test was used to test the flexural strength of rotary instrument-milled and saw-cut bars with the same dimensions. Analysis of variance and the Tukey honestly significant difference post hoc test were used to determine the difference among the groups (α=.05). IPS e.max CAD had the highest surface roughness and Lava Ultimate the lowest. Lava Ultimate had the smallest chipping factor and IPS Empress CAD the largest. The surface location significantly affected the chipping depth, area, and length (P<.05). A strong correlation was found between the decrease in flexural strength and the chipping length on the central tensile side of the rotary instrument-milled materials (R2=.62, P=.01), as well as the chipping depth (R2=.44, P=.01). Edge chipping was significantly associated with the material type, milling surface, and edge location and strongly correlated with a decrease in flexural strength.

Effect of ceramic type and thickness on the masking ability of chairside machinable all-ceramic crowns.

This study aimed to evaluate the influence of ceramic type and thickness on the masking ability and final aesthetic effects of chairside machinable all-ceramic crowns. Six kinds from three types chairside machinable ceramic materials (IPS e.max CAD HT/MT/LT, IPS Empress LT, and VITA Suprinity HT/T) in shade A2 were fabricated to slice specimens into 1.0, 1.5, and 2.0 mm-thick sections (n=10). The color parameters of the specimens against black and white tiles and four resin substrates (A2, A4, B3, and C4 shade) were measured with a spectrophotometer. The translucency parameter (TP) was calculated using color parameters measured over standard white and black backgrounds. The color differences (ΔE) were calculated between there substrate shades (A4, B3, C4 ) and A2 shade (control group). Two-way analysis of variance (ANOVA) was performed on the TP values. The two va-riables were ceramic type and ceramic thickness. Three-way ANOVA was used to determine the effects of ceramic materials, ceramic thickness, and substrate shades on the ΔE values, followed by Tukey test for multiple comparisons (α=0.05). Ceramic type, ceramic thickness, and substrate shade significantly affected the ΔE values (P<0.001). The L* and b* values of the specimens increased with increasing ceramic thickness, except in substrate A2, whereas the ΔE values decreased. The color difference of all 1.0 mm-thick specimens or all specimens over the substrates C4 shade exceeded the clinically acceptable threshold (ΔE>3.3). The masking ability of chairside machinable all-ceramic crowns is influenced by ceramic type and thickness, and ceramic material. The thickness of ceramic less than 2.0 mm cannot mask the gray shade abutment.

Effect of Surface Treatments on the Biaxial Flexural Strength of High Leucite Feldspathic Porcelains

The purpose of this study was to examine the effect of altering surface topography on the biaxial flexural strength (BFS) of four dental ceramics, Mir age (MI), Flexoceram (FL), Optec-HSP (OP) and IPS Empress (EM).Twelve groups of ten discs 123mm were prepared and fired according to the manufacturers' instructions. Ten specimens of each material were subjected to three surface treatments, polished, grit blasted and etched with 10% hydrofluoric acid (HF) for 2 minutes. Some specimens were gold coated for examination under Scanning Electron Microscope (SEM). BFS was determined using Lloyd M5K universal testing machine at a cross - head speed of 0.5 mm/min. A one-way ANOVA was used to evaluate the differences between groups.The results obtained showed that the only significant difference in the BFS was the 10% HF for OP and FL (One-way Anova, P&lt;0.05). The decrease in BFS is most likely due to an increased surface flaw size, such that surface initiated crack growth dominates over the bulk internal flaw size of the ceramics.The BFS of dental porcelain used in this st udy may be governed either by the internal or surface flaws dependi ng on the manner of surface preparation. Specimens etched with 10% HF became weaker for OP and FL ceramics.

Evaluation of Sealing Ability of New Composite Filling Material

This study was conducted to investigate the sealing ability (microleakage) of new composite restorative materials at tooth/composite interface.Thirty non carious, extracted human premolars teeth were mounted in acrylic resin, the teeth were randomly divided into three groups (n=10) according to the type of composite (tetric T-Econom, Evo ceram,IPS Empress). A standardize class V (5×3×2) mm dimensions cavity was prepared on the facial surface of each tooth (each group with corresponding bur type). After the specimens were filled with three types of composite restoration. They stored for one month in 37ºc distilled water, thermo cycled for 500 cycles between (5ºc &amp; 55ºc) and immersed in 2% methylene blue solution for 24h., and then sectioned longitudinally. For both occlusal and gingival margins, dye penetration at the tooth/composite interfaces were scored from 0-3 under stereomicroscope at a magnification x10. Data were analyzed using unpaired T-test, ANOVA, and Duncan’s multiple rang test at 5% significant level.Kruskal-wallis test show that there was a significant difference in microleakage between the three types of composite it represent that there was less microleakage in group filled with IPS Empress while tetric T-Econom show the highest leakage.There was no significant difference in microleakage between IPS Empress and Evo ceram composite filling.AS Conclusions; Within the limitations of this in vitro study the results show that there was less microleakage in the cavities filled with IPS Empress composite and EVO ceram composite as compared with Tetric T-Econom composite.

The effect of tooth bleaching using violet LED (405–410 nm) on the properties of resin-based composites

BackgroundThe objective of this study was to evaluate the effect of bleaching techniques, including or not the use of violet light (405–410 nm), on resin-based composites' color, surface roughness, nanohardness, and elastic modulus. MethodsNinety-six disk-shaped specimens (12 mm x 2 mm; n = 12) were prepared using Filtek Z350 XT (Z350) and IPS Empress Direct (ED) resin-based composites. After 24 h, specimens were stained in red wine for 28 days. After staining, specimens were divided into four experimental groups: 40 % Hydrogen Peroxide (HP); Violet Light (VL); 40 % Hydrogen Peroxide associated with Violet Light (HP+VL), and a control group - no treatment (NT). Specimens were evaluated at six experimental times: initial (24 h after light curing); after staining and after the 1st, 2nd, 3rd, and 4th bleaching sessions regarding the color change (ΔE00, L*, a*, b*, and WID); roughness (Ra), nanohardness and elastic modulus (GPa). Two-way analysis of variance for repeated measures was performed (α=0.05 %). ResultsThere was a statistically significant difference between staining and the 1st bleaching session for all ED groups (p<0.05). After the last bleaching session, there were no differences between the experimental and the control groups of both resin-based composites. Bleaching using violet light did not change the roughness, nanohardness and elastic modulus of the tested resin-based composites (p>0.05). ConclusionsAlthough hydrogen peroxide and violet light remove pigments from resin-based composites without affecting their surface roughness, nanohardness, and elastic modulus, the color change was similar to the one obtained by immersion in distilled water.

Evaluation of Retention and Fracture Strength of All Ceramic Crowns with Three Different Esthetic Cast Post-Core Systems.

This study investigates the fracture and retention strength of all-ceramic crowns with modified composite resin and ceramic cores compared to conventional casted post and core systems. A prepared human central tooth was initially scanned to design and 3D print the post and core. Subsequently, 40 bovine teeth were adjusted to accommodate the fabricated post and cores. They were then divided into four groups of 10 each: group 1 comprised cast cores without cover (control group), group 2 involved cast cores reduced and replaced with IPS Empress material (IPS group), group 3 consisted of cast cores covered with opaque composite (composite group), and group 4 included cast cores covered with opaque ceramic (ceramic group). Zirconia crowns were cemented onto all samples. After an aging process, pull-off and fracture strength tests were conducted. Fracture strength was determined by applying a compressive force at an angle of 135° to the tooth's longitudinal axis until the fracture occurred. For retention strength assessment, a universal testing machine with a 10 mm/min crosshead speed was employed. The resulting data underwent statistical analysis utilizing two-way analysis of variance (ANOVA) and Mann-Whitney U tests. The analysis revealed no significant difference in fracture strength among the groups (P-value = 0.997). However, the retention strength of the control and IPS groups was significantly higher than that of the other groups. There were no discernible distinctions among the three study methods regarding fracture strength. Nonetheless, the retention strength of the IPS group resembled that of the control group, surpassing that of the composite and ceramic groups.

Effect of Different Polishing Systems on Surface Roughness of IPS Empress Ceramic Materials

For evaluation and comparison of the effect of surface treatment (glazings, polishing with rubber wheel and diamond paste, and polishing with rubber wheel) on pressable porcelain (IPS Emax porcelain) surface roughness in comparison with non-treated surface. Forty-disc shaped specimens of baseplate wax with 10 mm diameter and 2 mm thickness have been prepared. They were invested and subjected to lost wax technique in fabricate the pressable ceramic. Following pressing, they have been divided randomly into four groups: Group A: no surface treatments, Group B: glazing (paste, HT, Ivoclar, Vivadent, Germany) glazing (paste, HT, Ivoclar, Vivadent, Germany), Group C: polishing with burs (DIAPRO TWIST, EVE, GmbH, Germany), and Group D: polishing with burs (DIAPRO TWIST, EVE, GmbH, Germany) and diamond paste (All in one, RENFERT, GmbH, Germany). For each specimen, examination of mean roughness profile (Ra) was performed for total surface roughness description. Specimens were stabilized with the acrylic holder used previously in the initial polishing procedure. A contact stylus profilometer was used to conduct a quantitative measurement of surface roughness in micrometers (µm) for all specimens. The highest (Ra) value was for control group (1.9520), whereas the lowest values were in group D (Polishing by rubber wheel .4670. One-way ANOVA test showed a high significant value at (P &lt;. 000), and LSD test showed a high significant value at (P &lt;. 000) when comparison was established among groups. From the results of the current study, we can conclude the following; polishing procedure for the surface of pressable ceramic with or without diamond paste produced better surface smoothness than glazed surface and non-treated surface and polishing with burs could be an alternative to glazing to provide smooth surface.

Effect of remaining pericervical dentin on biomechanical behavior of endocrown-restored molars with different materials: Three-dimensional finite element and Weibull analyses.

To evaluate the effect of remaining pericervical dentin (PCD) on the biomechanical behavior of endocrown-restored molars with different materials, six three-dimensional finite element (FE) models were reconstructed with different thicknesses and heights of pulp-chamber lateral dentinal wall (PCLDW). IPS Empress 2, In-Ceram Zirconia, and Lava Ultimate were selected as the materials. Compared with the Lava Ultimate FE models, the maximum tensile stress in the FE models using ceramics was higher in the endocrown and lower in the PCD surrounding it, and the overall failure probabilities with different PCLDW thicknesses and heights were similar, ranging from 9.8% to 12.9% under the normal lateral masticatory force, which were lower than the FE models using Lava Ultimate (ranging from 13.4% to 15.1%). Considering the bonding properties of ceramics, endocrown-restored molars using etchable lithium disilicate-reinforced glass ceramic exhibit superior longevity due to the stress shielding effect, regardless of the thickness and height of PCLDW.

A Comparative Evaluation of Enamel Wear Against Different Surface Finished Ceramics: An In Vitro Study.

An essential factor in the clinical acceptability of all ceramic restorations is the degree of tooth enamel wear. Wear of human enamel has been shown to produce traumatic occlusion, loss of vertical dimension, supra eruption of opposing teeth, periodontal disintegration, and temporomandibular dysfunction. To assess and compare enamel wear against two different ceramics (IPS Empress and Zirconia) and against three different ceramic surface treatments (autoglazed, overglazed, and polished). Zirconia and IPS Empress (Ivoclar Vivadent, Liechtenstein) ceramic samples totaled 30, of which 10 each underwent glaze, overglaze, or polishing with Diaglaze polishing paste. Using a horizontal pin on the disc machine, 60 mounted premolar tooth samples were produced and put through wear tests against ceramic discs. Prior to and following wear, the weight of the tooth samples was measured, and the results were then statistically analyzed using the student t-test, unpaired t-test, and analysis of variance (ANOVA). The qualitative data employed proportions, and the quantitative data used mean and standard deviation to express statistical information. The threshold of significance was set at 5% (α = 0.05). The results for weight loss after 25,000 cycles for ceramic surfaces that had been overglazed were just a little bit greater than those for ceramic surfaces that had been autoglazed and polished. In each of the various subgroups, it was shown that the weight loss values obtained with polished ceramic after 25,000 cycles were significantly lower than those obtained with autoglazed and overglazed ceramic surfaces (P=0.001). When comparing the results produced by the two separate primary groups, IPS Empress and Zirconia, there was no statistically significant difference between the autoglazed, overglazed, and polished groups. While statistically significant difference was seen for each subgroup of IPS and Zirconia (p ≤ 0.01), particularly Zirconia glazed (1.227) with a highly significant p-value of 0.00. The findings contribute to the understanding of the potential clinical implications of different ceramic materials and surface finishes in restorative dentistry, offering valuable insights for practitioners in their treatment decisions. Further research and clinical observations may be needed to corroborate these findings and guide evidence-based practices in dental restorations.

Bond durability of a silane-containing self-adhesive and conventional resin cements to CAD/CAM glass and hybrid ceramics

To evaluate the effect of CAD/CAM materials surface treatments for bonding of different cementing systems on shear bond strength, including conventional and silane-containing resin cements, after 24 h and one year of water storage. Samples (12 mm × 6 mm × 1 mm) of each CAD/CAM material (IPS E.Max; Suprinity; Enamic; Cerec Bloc; IPS Empress) were divided into 4 groups: G1) 4.5% hydrofluoric acid (HFA) + silane + adhesive + RelyX Veneer (conventional); G2) HFA + Clearfil Ceramic Primer + Tooth Primer + Panavia V5 (conventional); G3) HFA + Panavia SA Cement Universal; G4) blasting with Al2O3 + Panavia SA Cement Universal. After the bonding procedures, two resin cement cylinders (1.5 mm × 1.5 mm) were constructed on each sample and tested after 24 h or one year of water-storage, using shear bond strength testing (n = 10). Data were submitted to generalized linear models’ analysis (p < .05). The conventional treatment for glass ceramics with HFA and silanization or priming (G1 and G2) did not necessarily yielded higher bond strength than the simplified technique (G3 and G4). For IPS E.Max and Suprinity, all protocols had bond strength reduction after one year. For Enamic, Cerec Bloc and IPS Empress, G3 did not reduced statistically at one year. Panavia SA Cement Universal seemed not appropriate when IPS E.Max and Suprinity were blasted with Al2O3. On the other hand, the bond strength to etched or blasted with Al2O3 Enamic, Cerec Bloc and IPS Empress showed no difference or was higher than conventional luting protocols.

Effect of surface treatment on the repair bond strength of OMNICHROMA and Charisma Diamond ONE resin composites bonded to variable substrates

ObjectivesTo compare repair bond strength of OMNICHROMA and Charisma Diamond ONE resin composites bonded to variable composite substrates. Also, to evaluate the influence of different surface treatments on repair bond strength. MethodsA total of 80-disc shaped specimens was fabricated using two resin based composite materials; IPS Empress Direct Enamel and OptiShade (n = 40). Substrate discs were thermocycle 5000 cycles then each substrate material was subdivided based on the surface treatment into two groups; air particle abrasion (APA) and silicon carbide grinding (SiCr) both groups followed by phosphoric acid etching. All groups received a single bond universal adhesive application prior to repairing with composite, in a smaller disc shape. All specimens were thermocycled for 10,000 cycles prior to shear bond strength testing and subsequent failure analysis. Statistical analyses were conducted and the level of statistical significance was set at 0.05. ResultsThe comparison of mean values (considering the combination of the two types of substrates, surface treatments and repairing materials) showed a highly statistically significant difference in the shear bond strength among the eight study groups (p < 0.0001). The highest value of mean shear bond strength was associated with OptiShade substrates repaired by Diamond ONE (38.6 ± 2.4). Meanwhile, the lowest value was recorded for the SiCr treated OptiShade group repaired by Diamond ONE (13.6 ± 2.3). The failure analysis revealed that cohesive mode of failure was the most predominant. ConclusionOmnichroma showed higher repair bond strength values with SiCr surface treatment. Meanwhile, Charisma Diamond ONE had better bond strength with APA. Surface pretreatment had a significant impact on the repair bond strength where APA groups had significantly higher values compared to SiCr groups. Clinical Significance: Within the limitation of the present study; APA is recommended as surface pretreatment for improved bond strength in restorative composite repairs.

Post-fatigue fracture load, stress concentration and mechanical properties of feldspathic, leucite- and lithium disilicate-reinforced glass ceramics

ObjectiveTo evaluate the mechanical properties of different CAD/CAM ceramic systems and the post-fatigue fracture and stress distribution when used as cemented crowns. Materials and methodsSixty (60) CAD/CAM monolithic crowns were milled using three different ceramic materials (FD – Feldspathic [Vita Mark II]), LE - Leucite-based ceramic [IPS Empress CAD] and LD - Lithium Disilicate [IPS e.max CAD]) and adhesively cemented on resin composite dyes. Specimens were stored in distillated water (37 °C) for 7 days. After, half of the crowns were submitted to immediate fracture load test while the other half was submitted to fatigue cycling. The average cement layer of approximately 80 μm was assessed using scanning electron microscopy (SEM). The average thickness was used in the three-dimensional (3D) Finite Element Analysis (FEA). For each ceramic material, the density, Poisson ratio, shear modulus, Young modulus, fracture toughness, and true hardness were assessed (n = 3). The data was used to assess the Maximum Principal Stress throughout 3D-FEA according to each material during load to fail and post-fatigue. Data were submitted to two-way ANOVA and Tukey test (α = 0.05). ResultsLD showed the highest compression load, density, shear modulus, Young modulus, fracture toughness and true hardness values. While LE presented the lowest mechanical properties values. There is no difference in the Poisson ratio between the evaluated ceramics. ConclusionLD was susceptible to aging process but presented stronger physicomechanical properties, showing the highest post-fatigue fracture load and highest stress magnitude.

Does Sterilization Affect the Performance of Single-Step Resin Composite Polishers?

(1) Background: Single-step polishers are used extensively for resin-composite polishing. The purpose of this study was to evaluate the effect of sterilization on their performance. (2) Methods: Optrapol Next Generation/Ivoclar-Vivadent, Jazz Supreme/SS White, Optishine Brush/Kerr and Jiffy Polishing Brush/Ultradent were used for polishing a nanohybrid resin composite (IPS Empress Direct/Ivoclar-Vivadent). Polishers (n = 40) were microscopically inspected before use. After polishing, surface roughness (Sa, Sz, Sdr, Sci) and gloss were determined. Polishers were subsequently sterilized and microscopically re-examined. The process was repeated four times on new samples (n = 200). Data were analyzed using the Friedman test and Wilcoxon post hoc test, at α = 0.05. (3) Results: Optrapol's performance improved after the first sterilization for Sa and gloss, whereas it declined after the fourth sterilization for Sa. Jazz's, improved after the second sterilization for Sa and gloss and after the third sterilization for Sdr. An improvement trend was observed for Optishine after the first sterilization, but not statistically significant. Sa, Sz, and gloss declined after the fourth sterilization. Jiffy's performance was inconsistent, with a trend of performance loss after the fourth sterilization. (4) Conclusions: Performance of all polishing systems improved after the initial sterilization, but deteriorated after the fourth sterilization cycle. However, their performance can be considered clinically acceptable for a longer period of use.

Fracture Load of Veneered and Monolithic Single-Unit Fixed Dental Prostheses Made from the High-Performance Thermoplastic Polyphenylene Sulfone

To investigate the fracture load of different veneers for monolithic single-unit fixed dental prostheses (FDPs) made of a novel potential framework material, polyphenylene sulfone (PPSU). The fracture loads of four PPSU frameworks with different veneers (manual polymer veneer with Ceramage Body A3B; prefabricated polymer veneer with Novo.lign; digital polymer veneer with Telio CAD; digital ceramic veneer with IPS Empress CAD) and a monolithic control group (PPSU, Gehr) were examined initially and after 1,200,000 masticatory (50 N, 1.3 Hz) and 6,000 thermal cycles (5°C/55°C). Fracture analysis was performed using light microscope imaging. Fracture types were classified, and relative frequencies were determined. Univariate analysis of variance, post hoc Scheffé, partial eta squared, Kruskal-Wallis test, and Weibull moduli using the maximum likelihood estimation method were calculated. The defined level of significance was adjusted by Bonferroni correction (P < .005). Aging did not affect the fracture load values. Single-unit FDPs with a digital ceramic veneer showed lower values than monolithic and manual polymer-veneer specimens. Single-unit FDPs with a prefabricated and digital polymer veneer were in the same value range as specimens with a manual polymer and digital ceramic veneer. No differences were observed between manual polymer veneer and monolithic single-unit FDPs. All veneered specimens showed a fracture of the veneer. For monolithic single-unit FDPs, a plastic deformation was observed. Veneered and monolithic PPSU showed sufficient fracture load values to indicate successful clinical use in single-unit FDPs. The choice of veneering method and material may play a minor role.

Effect of tooth brushing simulation on the surface properties of various resin-matrix computer-aided design/computer-aided manufacturing ceramics.

The purpose was to investigate the alterations in surface properties of different resin-matrix CAD/CAM ceramics following tooth brushing simulation (TBS) and compare them with a direct resin composite and a glass ceramic CAD/CAM material. Four resin-based CAD/CAM restoratives (Brilliant Crios-BR, Lava™ Ultimate-LV, Grandio Blocs-GR and Shofu Block HC-SH), a leucite-reinforced glass ceramic (IPS Empress® CAD-EC) and a resin composite (Filtek™ Z250-FZ) for direct restorations were tested. In particular, surface loss, hardness, roughness and morphology were investigated utilizing confocal microscopy, scanning electron microscopy and nanoindentation tester. TBS was conducted for 4 × 15 min on the surface of the samples and then the changes in their surface properties were evaluated. After TBS, all the experimental groups exhibited surface loss to different extent. FZ and BR presented the highest surface loss, while EC and GR the lowest (p < 0.05). Regarding surface roughness, all the tested materials exhibited increase after TBS (p < 0.05), except LV (p = 0.099). EC presented the lowest Sa values, while FZ and BR the highest (p < 0.05). Changes in surface morphology were in compliance with the results of surface roughness and also surface hardness was correlated with surface loss. The tested resin-matrix CAD/CAM ceramic restorative materials showed a competent behavior against abrasive forces applied during TBS. Surface loss and roughness changes were material dependent and superior compared to a resin composite for direct restorations, while in comparison with a leucite-reinforced glass ceramic exhibited inferior properties. Tooth brushing affected differently the surface of the tested restorative materials. However, the abrasive wear that was induced was negligible. Clinical studies are necessary to ascertain if there is clinical significance of these surface alterations that may demand repair of such restorations.

Effect of Polishing Systems on Translucency Parameter of the Resin Composites after Aging

The purpose of this study was to evaluate the effect of finishing/polishing systems on the translucency parameter (TP) of resin composites after accelerated artificial aging (AAA). Four composite resins (Filtek Z250, Admira, IPS Empress Direct, Clearfil Majesty Esthetic) were evaluated. Thirty samples were prepared with each resin composite and divided into three subgroups: control (Mylar strip), disc (Optidisc), and rubber (Dimanto) (n=10). The spectrophotometer was used to determine color measurements. TP was calculated the using the CIEDE 2000 formula. Data were analyzed using Generalized Lineer Model (p[0.05). The three factors (composite resin, finishing/ polishing, and AAA) had no statistically significant influence on the TP. However, composite and finishing/polishing influenced the TP. Filtek Z250 showed the lowest TP values and the IPS Empress Direct showed the highest TP values before and after AAA. Polished groups showed higher TP values than control groups before and after AAA. IPS Empress Direct with Dimanto had higher TP values than other groups (except for IPS Empress Direct with Optidisc); Filtek Z250 with finishing/polishing groups showed lower TP values than other groups. Composite type and finishing/polishing systems influenced TP values. Unfinished groups exhibited lower TP values than finished groups. There was no difference in TP values between finishing/polishing systems (Dimanto and OptiDisc).

Evaluation of shade matching in the repair of indirect restorative materials with universal shade composites.

To evaluate color differences in repair of indirect ceramic and resin nanoceramic CAD/CAM blocks with two universal shade composites after different surface preparations. 120 samples were prepared from IPS Empress and GC Cerasmart270 CAD/ CAM blocks and thermocycled (5000 cycles, 5°C-55°C). Initial colors of sample surfaces were measured using a spectrophotometer. Rectangular prism-shaped cavities were prepared and repaired with Tokuyama Universal Bond/Omnichroma and G-Multiprimer/G-Premio/Essentia Universal following surface preparation with aluminum oxide, Cojet, and bioactive glass (Sylc). Repaired samples were thermocycled (5000 cycles) and color measurement was performed. Color coordinates L*a*b* were recorded, and color differences were calculated using the CIELab formula. Color differences between pre-and post-repair (ΔE1) and between post-repair and post-aging (ΔE2) were determined. Data were analyzed using Three-way ANOVA with a significance level set at p<0.05. ΔE1 values in all subgroups exceeded the threshold of 3.3. No significant difference was found between the surface preparation processes regarding ΔE1 values. There was no significant difference between the composites and bonding agents in ΔE1 values, except for Cerasmart/Sylc and Empress/Sylc groups. No statistically significant difference was detected in ΔE2 values between the surface preparation treatments in all groups. (p >0.05). Color match of the universal shade composites, which are preferred to increase the esthetic satisfaction and to simplify repair procedures, were found above the acceptable threshold. Post-aging color stability of universal shade composites was below the acceptable threshold.

Effects of Streptococcus mutans and its fluoride resistant strains on the adhesion of CAD/CAM ceramics to teeth and resin.

The similar elastic modulus of resin-matrix ceramics to dentin has resulted in their recent widespread application clinically. Nevertheless, the bacterial environment of oral cavity can degrade the resin composite. The objective was to analyse the effect of S. mutans and its fluoride-resistant strains on the adhesion of three CAD/CAM ceramics. S. mutans UA159 (UA) was identified, and its fluoride-resistant strain (FR) was induced. For crack observation, three kinds of CAD/CAM ceramics (IPS Empress, Lava Ultimate and Vita Enamic) were bonded with tooth complex (enamel, dentin and flowable resin) through adhesive. For micro-tensile test, ceramics were bonded with flowable resin, and cut into strip test pieces. Then specimens were immersed into the UA, FR and the control solution (BHI) separately for 14 d. Ceramic-adhesive interface and adhesive-tooth complex interface were observed and analyzed through electron microscope and stereomicroscope. Micro-tensile test was conducted. Specimens in bacterial solutions had more cracks and comparatively weaker micro-tensile strength than those in BHI. In ceramic-adhesive interface, Lava Ultimate produced the most cracks. In adhesive-tooth complex interface, adhesive-dentin produced the most cracks. Meanwhile, IPS Empress had the strongest micro-tensile strength when bonded with resin. S. mutans and its fluoride resistant strain can cause cracks in the bonding of ceramics and dental tissue, especially resin-matrix ceramic and dentin, and weaken the bonding strength between ceramics and resin.

Repair Bond Strength of Aged Composite Resins Using Different Surface Treatment Protocols.

This study evaluated shear bond strength (SBS) of thermally aged composite resins repaired using different surface protocols. Four-hundred composite resin samples were made using the following materials (100 samples per material): Filtek Z350XT (FXT); Spectra Smart (SSM); IPS Empress Direct (EDI); and Forma (FOR). Each group's samples were then divided into 10 groups (n = 10 samples per group): G1: no surface treatment; G2: phosphoric acid-etching + universal-adhesive (PU); G3: surface roughening + PU (RPU); G4: RPU + silane (RPSU); G5: surface roughening + hydrofluoric acid-etching + universal adhesive (RHU); G6: RHU + silane (RHSU); G7: dry sandblast + PU (DsPU); G8: DsPU + silane (DsPSU); G9: wet sandblast + PU (WsPU); and G10: WsPU + silane (WsPSU). G1 was freshly repaired, and G2 to G10 were thermally aged before repair. Specimens were tested for SBS, and the failure type was observed with a magnifying loupe. Representative images were obtained using a scanning electronic microscope. Data were analyzed by two-way analysis of variance and Tukey post hoc tests (P = .05). Differences were detected among different surface treatments and among different composite resins with equal surface treatments (P < .05). SBS means ranged from 10.48 (FOR:G2) to 20.70 (FXT:G7). The highest SBS values were seen in G7 to G10 (P > .05), while lowest values were generally observed for G2. G1 showed higher results compared to G2 (P < .05), except for EDI (P > .05). Most failures corresponded with cohesive type. In general, thermally aged composite resin presented a decreased repair bond strength potential when no additional surface treatment was applied. Sandblasting improved the SBS of repaired aged composite resins.

Digital image analysis of fluorescence of ceramic veneers with different ceramic materials and resin cements.

The objective of this study was to analyze the effect of the type of ceramics and resin cements on the fluorescence of ceramic veneers under the 405 nm UV-light by digital imaging. One hundred and ninety-two veneers were fabricated using three types of ceramics (IPS e.max CAD, IPS Empress CAD, and Zenostar). Eight pieces of substrates were made of resin-nano-ceramic (Lava Ultimate). The level of fluorescence for each sample cemented with the substrate using three kinds of resin cements (RelyX U200, Variolink N, and Choice 2) was analyzed by using histogram data of luminosity from Adobe Photoshop software. Furthermore, the fluorescence values were evaluated by two-way ANOVA and Tukey's test. The highest fluorescence values were observed for the IPS e.max CAD cemented with Choice 2 cement, followed by IPS Empress CAD, and Zenostar the lowest. The final fluorescence intensity of ceramic veneer is affected by ceramic materials and resin cements.