IPS Empress Research Articles

Effect of Two Different Surface Treatments on Retention of Cosmopost with Two Different Core Materials.

ObjectiveThe objective of this study was to determine the effect of Cosmopost’s two different surface treatments (sandblasting and silica coating) on persistence to various core materials using push-out test set-up.Material and MethodsA total of 30 Cosmoposts was used in this study. Cosmoposts were divided into three groups (10 samples each) according to the post-surface treatment received. Every category was additionally subdivided into two subgroups according to the type of core material (n = 5 samples). A specially designed copper mold was used for construction of different core materials with standardized dimensions around the posts, in such a way to ensure that the posts will be centralized. Surface roughness was estimated for all Cosmoposts, following different surface treatments using SEM. Cylindrical cores were fabricated of either composite resin or heat-pressed zirconia-containing glass-ceramic (IPS Empress Cosmo, Ivoclar Vivadent). Following the construction of different Core materials, samples were subjected to push-out test set-up to Evaluate the impact of various treatments on post/core bond strength. Data were collected, tabulated and statistically analyzed. SEM was performed on Cosmoposts following debonding of different post/core samples to determine their mode of failure.ResultsResults of push-out bond strength revealed that core material, surface treatment and the interaction between the two variables using Two-way ANOVA had a statistically significant effect on mean push-out bond strength. Regarding the effect of type of core material on Push-out bond strength, results showed that IPS Empress Cores showed statistically significant higher mean push-out bond strength to Cosmopost (36.4±9.7MPa) than composite cores (15.8±2.5 MPa).ConclusionWithin the limitations of this study, direct heat-pressed ceramic core was more beneficial for zirconia post buildups, than Composite Cores, since they provided higher bond strength. Thanks to a double improvement: increase in fracture resistance and retentive capacity to post. Also, Tribochemical Silicacoating technique was proved to be more effective in Cosmopost treatments than sandblasting technique.

Effects of 16% Carbamide Peroxide Bleaching on the Surface Properties of Glazed Glassy Matrix Ceramics.

Objective To determine the influence of the home bleaching agent, Opalescence PF, on the surface roughness and microhardness of glazed glassy matrix CAD-CAM ceramics. Materials and Methods. The 28 sintered leucite- and lithium disilicate-reinforced ceramic specimens (IPS Empress CAD and IPS e.max CAD) were divided into control and bleached groups. The home bleaching agent was applied to specimens of bleached groups for 7 days. The surface roughness and microhardness of all specimens were measured. A scanning electron microscope was used to evaluate the surface properties. The data were statistically analyzed by two-way ANOVA. Results The control e.max CAD showed the lowest surface roughness values. For both Empress and e.max CAD, surface roughness was significantly higher for the bleached group (p < 0.05). No significant differences in microhardness were observed. Conclusions According to our study, patients should be careful when using home bleaching agents because whitening agents can affect the mechanical properties of full ceramic restorations like e.max CAD and Empress CAD. Ceramic polishing may be required in clinical situations where ceramic restorations are accidentally exposed to bleaching gels.

Bond strength of modern self-adhesive resin cements to human dentin and different CAD/CAM ceramics

The aim of the study was to evaluate the shear bond strength of CAD/CAM ceramics to dentin after cementation with conventional or self-adhesive resin cements. Three self-adhesive, self-etching cements (Panavia SA, RelyX U200, Maxcem Elite), and one conventional cement (Panavia V5), were selected to lute three CAD/CAM ceramics (IPS Empress CAD, IPS e.max CAD, IPS e.max ZirCAD) onto the dentin. The bond strength was evaluated using a shear strength test according to the PN-EN ISO 29022:2013-10. Evaluation of the differences was performed using the Statistica software. Failure modes were analyzed using a light microscope. All the studied cements differed (regardless of the ceramic type) in the bond strength. The highest bond strength was observed in Panavia V5, lower - in RelyX U200 and Panavia SA, and the lowest - in Maxcem. For IPS e.max ZirCAD, it was observed that compared to Panavia V5, the other cements were characterized by a significantly higher bond strength. For the IPS Empress CAD and the IPS e.max CAD, Panavia V5 displayed the highest bond strength. For all the studied self-adhesive cements, the failure of adhesion between the cement and dentin was predominant mode. Significant differences were found in the shear bond strengths of the CAD/CAM ceramics luted to dentin using tested self-adhesive and conventional cements. The bond strength depended on the combination of ceramic and cement. The IPS e.max ZirCAD had the highest bond strength to dentin after cementation with RelyX U200, while the IPS Empress CAD and IPS e.max CAD - with Panavia V5.

The micro-shear bond strength of two different repair systems to indirect restorative materials

Introduction The aim of this study was to evaluate the micro-shear bond strength (μSBS) of different repair systems (Clearfil Repair, iGOS Repair) to restorative materials for CAD/CAM (Cerasmart, Lava Ultimate, InCoris TZI , VITA Suprinity, VITA Mark II, IPS e.max CAD, IPS Empress CAD). Methodology The 140 1.2 mm-thick specimens were prepared from CAD/CAM blocks (n=20) and thermocycled (10,000 cycles, 5–55°C, dwell time 20s). The specimens were randomly divided into two groups according to the repair system: Clearfil Repair (40% phosphoric acid+mixture of Clearfil Porcelain Bond Activator and Clearfil SE Bond Primer+Clearfil SE Bond+CLEARFIL MAJESTY ES-2) and iGOS Repair (40% phosphoric acid+ Multi Primer LIQUID+ iGOS Bond+ iGOS Universal). The composite resins were polymerized. All specimens were stored in distilled water at 37°C for 24 hours. The μSBS test was performed with a micro-shear testing machine (at 1 mm/min). The data were analyzed using two-way ANOVA, Tukey’s multiple comparison tests at a significance level of p&lt;0.05. Each failure modes were examined under a stereomicroscope at×16 magnification. Results The type of CAD/CAM restorative material and repair system showed a significant effect on the μSBS (p&lt;0.05). Specimens repaired with the iGOS Repair system showed the highest μSBS values than the Clearfil Repair system among all tested materials except for the InCoris TZI group (p&lt;0.05). Conclusion All groups, except for the InCoris TZI group, repaired with iGOS Repair system showed higher μSBS than Clearfil Repair. The type of restoration and repair material is important in the success of the fracture repair.

Influence of Preparation Depth and Design on Stress Distribution in Maxillary Central Incisors Restored with Ceramic Veneers: A 3D Finite Element Analysis.

To evaluate the influence of different preparation designs and depths on the stress field developed in maxillary central incisors restored with veneers made with different ceramic materials using finite element analysis (FEA). A linear static three-dimensional finite element analysis model was used with the aid of reverse engineering to develop digital models of maxillary central incisors restored with ceramic veneers, according to two different preparation depths (thin vs deep) and two different preparation designs (feather edge vs butt joint). Three ceramic systems were tested: (i) feldspathic porcelain, (ii) heat pressed glass ceramic IPS Empress 2 (Ivoclar Vivadent AG), and (iii) heat pressed glass ceramic IPS e.max-Press (Ivoclar Vivadent AG). Each model was subjected to a compressive force of 200N applied to the palatal surface 2 mm below the incisal edge. The longitudinal axis of the restored tooth formed an angle of 130o with the direction of the force. The biomechanical behavior of the different models was examined according to the von Mises stress criterion. Statistical analysis was performed using nonparametric confidence interval estimation using bootstrapping. The maximum observed stress values were calculated and found to be similar between prepared and intact teeth. The cervical margin of the veneers displayed the highest von Mises stress values. Irrespectively of the depth and preparation design, the biggest von Mises stress values were observed at the veneer structures with the following order: (i) IPS Empress 2, (ii) IPS e.max-Press, (iii) feldspathic (p = 0.001). Preparation depth resulted in statistically significant differences (p = 0.001) in the stress distribution in the majority of tested structures. As the preparation depth was increased, the stresses within the veneer structure and the tooth structures were decreased. No statistically significant differences were detected in the stresses among the different restored models, when the preparation design was considered. This FEA study suggests that ceramic veneers could restore the biomechanical behavior of prepared central incisors and made it similar of that of an intact tooth. Regardless of the preparation depth and design and the ceramic system used, the cervical margin of ceramic veneers presents the highest von Mises stress values. When feldspathic porcelain was compared with lithium disilicate (IPS e.max Press), the latter displayed the lowest transfer of stresses to dental tissues. An increase in preparation depth resulted in a statistically significant stress decrease in both the veneer and the tooth.

DETERMINATION OF ABRASION RESISTANCE OF DENTAL MATERIALS USED FOR DIRECT AND INDIRECT RESTORATIONS OF TEETH OF THE FRONTAL GROUP

Introduction. Tooth restorations fabricated of any material carry multiple loads in the oral cavity. The ability of restoration materials to resist the forces of shear, bending, and abrasion without losing their functional and aesthetic properties is a valuable factor on which the choice of a dentist and a patient will depend on the stage of coordinating the type and material of restoration. Objectives. Determination of the abrasion resistance of samples of dental restoration materials: light composite resin samples EsthetX (Dentsply-Sirona), feldspatic ceramics EX3 (Noritake), ceramics based on leucite glass IPS Empress Esthetic (Ivoclar Vivadent). Materials and methods. To carry out the corresponding experiment, plates 10 × 10 mm in size and 1 mm thick were prepared from the tested restoration materials. Before testing, the samples were degreased with ethyl alcohol and their density was determined by hydrostatic weighing. Samples of plates (composite or ceramic) were fixed on plates of organic glass. Abrasion of the samples was determined by 200 revolutions of the volcanic disk. At the end of the elongated shoulder of the lever suspended the load, selected so that the shoulder of the lever was in the test in a horizontal position. After testing, the samples were weighed again. Results. Ceramic based on leucite glass has the most optimal parameters from the specific gravity and abrasion resistance. structures made of this material will have a significantly lower weight compared to feldspar ceramics (apr. 43.1% lighter), and 14.2% composite resin material with the same restoration thicknesses. Conclusions. Expluatation of restorations made of leucite glass, according to the experiments, will also be a more extended due to the high abrasion resistance of leucite glass in comparison with the light curing composite resin (17.5% higher), and 77.5% higher comparing to feldspatic ceramics.

Comparative Study Between Monolithic Translucent Zirconia (Y-TZP) and IPS Empress 2 in Marginal Fit and Fracture Strength

Abstract :Purpose : The aim of this study was to compare between Monolithic Translucent Zirconia (Y-TZP) and IPS e.max press in marginal fit and fracture strength. Materials and methods, forty ceramic crowns were fabricated, : Then divided into 4 groups: Group A: Ten monolithic TZI CAD/CAM zirconia crowns (n=10) Group B: Ten monolithic IPS e.max press crowns (n=10), Group C: Ten veneered ZI CAD/CAM zirconia core (n=10), Group D: Ten veneered IPS e.max press core (n=10),then Each group was subdivided into two subgroups: Subgroup 1: Samples not subjected to thermocycling (n=5) as control. Subgroup 2: Samples subjected to thermocycling (n=5). The crowns were cemented to corresponding epoxy resin dies. The marginal fit was measured and scanned with digital microscope. The fracture strength of restoration was measured by using universal testing machine with a load 5 KN. The obtained data were collected, tabulated and statistically analyzed. Results of marginal fit: Results showed that, the vertical marginal gap values of all groups were within the clinically acceptable range. Results of fracture resistance: The fracture strength of monolithic translucent Y-TZP is (3484.28 N) considerably higher than monolithic IPS e.max press (1515.45 N), followed by veneered ZI zirconia (1483.84 N), and finally veneered IPS e.max press (1091.64 N) after thermocycyling. Conclusions: The vertical marginal gap values observed were all within the clinically acceptable range (120 μm). The monolithic crown groups recorded higher fracture strength than veneered groups.

Impact of storage media and temperature on color stability of tooth-colored CAD/CAM materials for final restorations.

This in-vitro study examined the impact of storage solution, storage duration, and storage temperature on discoloration of three tooth-colored CAD/CAM materials for final restorations. Specimens (N = 288; n = 96 per material) with a thickness of 1 ± 0.03 mm of the following CAD/CAM materials were fabricated: resin composite (Lava Ultimate, 3M), polymer-infiltrated ceramic (VITA Enamic, VITA Zahnfabrik), and leucite ceramic (IPS Empress CAD, Ivoclar Vivadent). After baseline measurement, specimens were stored in red wine, curry solution, cress solution, and distilled water at 37°C or 55°C. The discoloration was measured using a spectrophotometer (Lambda 35 Perkin Elmer, Perkin Elmer Inc.) after 1 and 7 days storage. Data were analyzed using four-way ANOVA followed by the Scheffé post-hoc test and partial eta squared (ηP²) test (p < 0.05). The highest influence on ∆E was exerted by storage duration (ηP² = 0.295, p < 0.001), followed by storage solution (ηP² = 0.171, p < 0.001), CAD/CAM material (ηP² = 0.049, p < 0.001), and storage temperature (ηP² = 0.033, p < 0.001). Specimens stored for 7 days in staining solutions showed more discoloration than those stored for just 1 day. Higher ∆E values were achieved for specimens stored in curry solution, followed by red wine, cress solution, and distilled water. Resin composite Lava Ultimate showed larger ∆E values compared with the resin hybrid ceramic VITA Enamic and leucite ceramic IPS Empress CAD. Specimens stored at 37°C showed significantly less discoloration than those stored at 55°C. The degree of coloration of the materials depends on food and temperature and was most pronounced with Lava Ultimate.

Color stability of Lucirin-photo-activated resin composite after immersion in different staining solutions: a spectrophotometric study.

IntroductionExceptional optical properties characterize teeth. As such, an esthetic restorative material should enable the dental professional to imitate the optical properties of natural teeth accurately. IPS Empress Direct was introduced to the market with the claim that it can mimic optically dental tissues with superior clinical performance.AimTo evaluate the ability of IPS Empress Direct to mimic tooth appearance and color and resist staining.Materials and methodsThree disc specimens were prepared for each shade of enamel and dentin of Lucirin-based composite, IPS Empress Direct (Ivoclar Vivadent) (A1, A2, A3, B1, and B2) (total of 60). The specimens were submitted to colorimetric evaluation in comparison after immersion in 10 different solutions (coffee, coffee with sugar, coffee with milk, red tea, red tea with sugar, red tea with milk, tomato juice, pomegranate juice, coke, and distilled water as a control group) for 4 weeks using spectrophotometric analysis.ResultsAfter plotting the data and conducting linear regression analyses, IPS Empress showed high potential in mimicking the optical properties of natural tooth color according to the CIE color space. Three solutions showed a change in color higher than 3, coffee, coffee with sugar, and red tea. All other solution showed changes in color that are acceptable clinically.ConclusionIPS Empress Direct can satisfactory mimic teeth appearance and color while manifesting high stability of color resisting staining upon clinical aging.

Comparative Evaluation of Esthetic Materials Used for Fixed Partial Prosthesis Placed On Vital Abutments on The Periodontal Status: A One Year Retrospective Follow-Up

BACKGROUND: The replacement of missing teeth with fixed partial dentures is largely dependent upon the health and stability of the surrounding periodontal structures. FPDs are often prepared on vital teeth as abutments. Esthetic materials have become popular in fixed prosthodontics today.&#x0D; AIM: The present study aimed to assess the long term effect and tissue responses of various types of fixed partial prosthesis placed on vital abutment teeth on the periodontal parameters both clinically and radiographically.&#x0D; MATERIALS AND METHOD: Following ethical committee approval, the study group comprised of 87 abutment teeth in 41 systemically healthy patients (24 males and 17 females) aged between 18 – 45 years who had received 3 unit fixed prosthesis(IPS empress, PFM or zirconia), having equigingival margins using vital teeth as abutments. The following parameters were assessed at the time of bridge placement and 1 year follow up – CAL, Probing depth, Distance between CEJ/ cervical crown margin and alveolar crest of the abutment teeth(radiograph).&#x0D; RESULTS: Statistical analysis carried out by SPSSV22 software revealed significant changes in clinical parameters with IPS empress and radiographic parameters with PFM and Zirconia from time of bridge placement till the 1 year follow up.(P&lt;0.05).&#x0D; CONCLUSION: There seemed to be favorable responses of the periodontal tissues to the various esthetic materials used on vital abutments of FPDs.

Effects of Different Storage Conditions on Mechanical Properties of CAD/CAM Restorative Materials

The aim of this study was to evaluate mechanical properties of six new-generation all-ceramic materials for CAD/CAM (Lava Ultimate [LU], VITA Mark II [VM], InCoris TZI [IC], IPS e.max CAD [EM], VITA Suprinity [VS], IPS Empress CAD [EC]) and two different provisional restoration CAD/CAM materials (Telio CAD [TC], Vita CAD-Temp [VC]) after different storage conditions. 36 bar-shaped samples of 4 mm in width and 14 mm in length with 1.2 mm thicknesses were prepared from each material group (N=288). The specimens from each material were kept under three different storage conditions (n=12): under dry conditions at room temperature; 37°C distilled water for 7 days; and 37°C distilled water for 7 days followed by 10,000 thermal cycles. All specimens were subjected to a 3-point flexural test with a crosshead speed of 1.0 mm/min. The specimens were loaded until failure. Twelve fractured specimens after the flexural test from each group were used for the Vickers hardness test (under 300 gf of loading in 15 seconds). The flexural modulus, flexural strength and Vickers hardness values were separately analyzed with two-way analysis of variance, Tukey’s multiple comparison tests at a significance level of p&lt;0.05. There were statistically significant differences between materials and storage conditions according to flexural modulus, flexural strength and Vickers hardness values (p&lt;0.05). The flexural strength, flexural modulus and Vickers hardness values of LU, VC, TC, VS and IC decreased after water storage followed by thermal cycling (p&lt;0.05). The mechanical properties of provisional restoration CAD/CAM materials had showed a significantly decrease after water storage followed by thermal cycles but their mechanical properties were acceptable for fabrication of provisional restorations. The mechanical properties of VM, EC and EM were not affected by different storage conditions whereas IC and VS were affected.

Evaluation of the Fracture Strength of Different CAD/CAM Inlay Restorations After Accelerated Aging

Background: The purpose of this study was to compare the fracture resistance of inlay restorations manufactured by CAD/CAM using different materials after accelerated artificial aging.Methods: Class I inlay preparations were made for 40 mandibular molar teeth. The teeth were allocated into four groups (n=10) according to the type of manufacturing material used: feldspathic-ceramic (CEREC blocks); leucite-based glass-ceramic (IPS Empress CAD); resin nano-ceramic (Lava Ultimate); and a control (intact teeth). After obtaining digital impressions, restorations were designed and milled with CAD/CAM. Inlay restorations were cemented to the inlay cavities using a dual-polymerizing resin cement (Rely X Ultimate) and stored in distilled water at 37°C for a week. All the samples were then exposed to accelerated ultraviolet aging for 300 hours. Finally, a compressive load was applied to the samples until fracture. Statistical analysis was conducted using One-Way ANOVA and the Tukey HSD test (a=0.05).Results: The mean fracture strength values of the groups were; Control (1555.3±412.2 N)&amp;gt; Lava Ultimate (1525±394N)&amp;gt;IPS Empress CAD (1364.3±545.6N) &amp;gt; CEREC(1231.9±412.2N), respectively. However, there was no statistically significant difference in mean fracture strength among different inlay restoration groups (P&amp;gt;0.05). Fifty percent of the both CEREC and IPS Empress CAD groups and 60% of the Lava Ultimate group showed reparable fractures. Conclusion: The type of material used did not influence the fracture strength of inlay-restored molar teeth and inlay restorations did not weaken the strength of the restored teeth. Therefore, all of the tested materials are suitable for use in the posterior region. Keywords: Inlay, fracture strength, resin nano-ceramic, ceramic, CAD/CAM

Fatigue resistance of ultrathin CAD/CAM ceramic and nanoceramic composite occlusal veneers

ObjectiveThe fracture resistance of different ultrathin occlusal computer-aided design/computer-aided manufacturing (CAD/CAM) veneers was investigated under cyclic mechanical loading to restore combined enamel-dentin defects. MethodsEighty-four molars were reduced occlusally until extensive dentin exposure occurred with a remaining enamel ring. Twenty-four molars were ground flat for examination of highly standardized specimens, of which 8 were treated with uniformly flat 0.3mm IPS Empress CAD and 0.3 and 0.5mm IPS e.max CAD restorations. Sixty-four molars were anatomically prepared until dentin exposure and were restored using occlusal veneers with fissure/cusp thicknesses of 0.3/0.5mm from 3 different dental CAD/CAM materials: IPS Empress CAD, IPS e.max CAD and Lava Ultimate CAD/CAM. Teeth were etched with 37% phosphoric acid, and occlusal veneers were bonded using an adhesive luting system (Syntac Primer, Adhesive, Heliobond and Variolink II). Specimens were placed under cyclic mechanical loading in a chewing simulator (1 million cycles at 50N) and were examined for cracks after each cyclic loading sequence. The anatomical 0.3/0.5mm IPS e.max CAD specimens experienced an additional 1 million cycles at 100N. Kaplan–Meier survival curves and log-rank tests were used for data analysis. ResultsAll highly standardized and 0.3/0.5mm IPS e.max CAD specimens tolerated cyclic loading. One anatomical Lava Ultimate CAD/CAM and 10 IPS Empress CAD specimens showed cracks. SignificanceUltrathin occlusal veneers of lithium disilicate ceramic and nanoceramic composite showed remarkably high fracture strength under cyclic mechanical loading. These veneers might be a tooth substance preserving option for restoring combined dentin–enamel defects.

ASSESSMENT OF SHEAR BOND STRENGTH OF RESTORATIVE MATERIALS IN VARIOUS DEPTH OF HARD DENTAL TISSUE PREPARATION IN FRONT TEETH

In modern dentistry, there are two different approaches to the restoration of anatomy and aesthetics of anterior teeth. The most common is the option of direct restoration with using composite resin materials. The second option is the restoration with using ceramic materials that is carried out through the cooperation of the dentists and the dental laboratory technicians, or, alternatively, with various CAD-CAM systems directly at the dental office. This experiment was carried out by using teeth (premolars, incisors) without significant loss of hard dental tissues. Teeth with abrasion (all except 1st degree) were excluded from the test group. Within the framework of the planned study, the selected extracted teeth were prepared (a certain volume of hard tissues was removed from the vestibular side (a subgroup of the teeth prepared within in the enamel layer, and a subgroup of teeth with the exposed dentine). A total of 40 teeth were prepared (20 teeth with the exposed dentine, 20 with the enamel preparation). The tests were carried out by using a universal testing machine AUTOGRAPH AGS-J. A sample with a tooth was placed at the top of the device then the second part of the sample containing the plate of the material (composite or ceramic), was covered with the second part of the device to be tested, and neatly, trying to avoid applying tension to the adhesive butt joints, and then fastened to the lower clamping device of the tension testing machine. We created the shear forces before the sample was destroyed, paying attention to the character of adhesion line oddments. The results of the experiment have demonstrated that the most optimal shear strength is found out in the complex of hard tooth tissues and ceramic materials IPS Empress Aesthetic and EX3, in the teeth prepared within the tooth enamel layer. When using composite resin, the values studied are lower by 11,4% and 18,1%, (application of adhesion systems of 5th and 7th generations, respectively). In the cases when dentin is exposed, the shear strength decreases by 19,5% when using ceramics modified by leucite glass, by 17,3% in the case of application of feldspar ceramics, and by 8,4% and 13,2% for composite resin restoration when using adhesive systems of 5th and 7Ith generations respectively.

Study of Surface Structure Changes for Selected Ceramics Used in the CAD/CAM System on the Degree of Microbial Colonization, In Vitro Tests.

In the article has been presented an analysis of susceptibility of selected dental materials, made in the CAD/CAM technology. The morphology and structural properties of selected dental materials and their composites were determined by using XRPD (X-ray powder diffraction) techniques, as well as the IR (infrared) spectroscopy. Moreover, an adhesion as well as development of biofilm by oral microorganisms has been studied. It has been shown that a degree of the biofilm development on the tested dental materials depended on microorganism genus and species. Streptococcus mutans has demonstrated the best adhesion to the tested materials in comparison with Candida albicans and Lactobacillus rhamnosus. However, the sintered materials such as IPS e.max® and the polished IPS e.max® have showed the best “anti-adhesive properties” in relation to S. mutans and L. rhamnosus that have not formed the biofilm on the polished IPS e.max® sample. Furthermore, S. mutans have not formed the biofilm on both surfaces. On the contrary to S. mutans and L. rhamnosus, C. albicans has demonstrated the adhesive properties in relation to the above-mentioned surfaces. Moreover, in contrast to S. mutans and C. albicans, L. rhamnosus has not formed the biofilm on the polished IPS Empress material.

The contribution of ceramic thickness and adhesive type on the de-bonding strength of dental ceramic veneers using Er,Cr:YSGG laser.

Purpose: De-bonding strength of ceramic veneers by laser use needs to be evaluated in detail. The aim of this study, is to determine the contribution of ceramic thickness and cementing agents to the de-bonding strength of ceramic veneers using Er,Cr:YSGG laser. Methods: A total of 120 maxillary central incisors specimens were randomly divided into twelve groups on the basis of disc thickness, cementing agent, and Er,Cr:YSGG laser use. Under laboratory conditions, 120 IPS Empress II system discs 0.5mm, 1mm, and 2mm in thickness were applied to the tooth surfaces, for laser use. An Er,Cr:YSGG laser system was applied to the central surface of the IPS Empress II discs on specimens in all laser groups (Groups 1,3,5,7,9,11). Then the shear bond strength (SBS) for all specimens were tested with a testing machine at a speed of 0.5mm/min. The SBS values were considered as the de-bonding strength. Results: The mean de-bonding strength values for Groups 9 and 11 (0,5 mm disc thickness + laser application) have the lowest median load (0.000 N), while Group 4 (2mm disc thickness + no laser) has the highest median load (573.885 N). The de-bonding strengths of all the groups without laser application were higher than those of all groups with laser use. When laser is applied, the mean de-bonding strength decreases with decreasing disc thickness, and it reaches zero at 0.5mm thickness of discs cemented by self- or total-etch adhesives. Conclusions: The de-bonding strength decreases with laser use, and decreasing disc thickness. In the absence of laser, the mean de-bonding values of discs cemented by a total etch adhesive system are always higher than those of discs cemented with a self-etch adhesive system. Without any extra load, all 0.5mm thick discs were dislodged from teeth while applying or testing the laser.

La contribución del espesor de la cerámica y el tipo de adhesivo a la resistencia de desunión de las carillas dentales de cerámica con láser Er, Cr: YSGG.

Purpose: De-bonding strength of ceramic veneers by laser use needs to be evaluated in detail. The aim of this study, is to determine the contribution of ceramic thickness and cementing agents to the de-bonding strength of ceramic veneers using Er,Cr:YSGG laser. Methods: A total of 120 maxillary central incisors specimens were randomly divided into twelve groups on the basis of disc thickness, cementing agent, and Er,Cr:YSGG laser use. Under laboratory conditions, 120 IPS Empress II system discs 0.5mm, 1mm, and 2mm in thickness were applied to the tooth surfaces, for laser use. An Er,Cr:YSGG laser system was applied to the central surface of the IPS Empress II discs on specimens in all laser groups (Groups 1,3,5,7,9,11). Then the shear bond strength (SBS) for all specimens were tested with a testing machine at a speed of 0.5mm/min. The SBS values were considered as the de-bonding strength. Results: The mean de-bonding strength values for Groups 9 and 11 (0,5 mm disc thickness + laser application) have the lowest median load (0.000 N), while Group 4 (2mm disc thickness + no laser) has the highest median load (573.885 N). The de-bonding strengths of all the groups without laser application were higher than those of all groups with laser use. When laser is applied, the mean de-bonding strength decreases with decreasing disc thickness, and it reaches zero at 0.5mm thickness of discs cemented by self- or total-etch adhesives. Conclusions: The de-bonding strength decreases with laser use, and decreasing disc thickness. In the absence of laser, the mean de-bonding values of discs cemented by a total etch adhesive system are always higher than those of discs cemented with a self-etch adhesive system. Without any extra load, all 0.5mm thick discs were dislodged from teeth while applying or testing the laser.

Optical properties of computer aided design and computer aided manufactured materials for veneer restorations

Objective: To investigate the translucency parameters (TP) and the color parameters of computer-aided design and computer-aided manufacturing (CAD/CAM) materials for veneer restorations in order to guide clinical practice. Methods: Eleven groups of CAD/CAM materials (A2 shade) were included in this study: IPS e.max CAD HT/LT, IPS Empress CAD HT/LT, Lava(TM) Ultimate HT/LT, VITA SUPRINITY HT/T, VITA ENAMIC HT/T, VITABLOCS Mark Ⅱ, and were named as Group A, B, C, D, E, F, G, H, I, J, K. Each material was designed and milled to disk-shaped specimens (10.0 mm×8.0 mm×0.7 mm) (n=6). The specimens were polished with silicon carbide paper and the thickness of specimens were adjusted into (0.60±0.03) mm. The color parameters of specimens were individually measured with the colorimeter against black and white ceramic tiles background to obtain the TP values. The color parameters of the specimens against the composite resin background were also measured and the color differences (ΔE values) between specimens and the A2 shade tab were calculated. Results: One-way ANOVA showed that the translucency parameters of the 11 groups of materials were statistically significant (F=253.69, P<0.05). The ΔE values of CAD/CAM material groups ranged from 1.78 to 4.12 (ΔE values<5.5). Conclusions: The microstructure of CAD/CAM materials and the types of material translucency influence the optical properties. The CAD/CAM materials in this experiment have achieved color matching with the A2 shade tab.

EFFECT OF TWO DIFFERENT SURFACE TREATMENTS ON MICRO-SHEAR BOND STRENGTH OF CAD/CAM AND HEAT PRESSED GLASS CERAMICS

Objective: The aim of this study was to evaluate the micro-shear bond strength between a dual cured resin cement and five different types of ceramics in composition and techniques of construction, using two different surface treatments.Materials & methods: A total of 50 ceramic disks were made and divided into 5 equal groups according to material type IPS Empress CAD, IPS e.max Press, IPS e.max CAD, Vita Suprinity and PM9 (n = 10). Each group was subdivided into 2 subgroups according to surface treatment they will be subjected to (n=5). Subgroup I: Bonding surfaces were etched with 5% HF acid, then coated with Monobond S. Subgroup II: Monobond Etch & Prime was applied on the bonding surfaces. For standardization of bonding surface area, 5 plastic tubings distributed on the bonding surface of each disk were used to place the dual resin cement. The samples were then subjected to micro-shear bond strength.Results: Results showed insignificant difference in micro-shear mean values between the IPS Empress CAD subgroups while significant differences were found between the other subgroups within the same group. Monobond Etch & Prime surface treatment resulted in higher micro-shear bond strength compared with HF surface treated subgroups for all the tested materials except for the PM9 and IPS e.max CAD. Conclusions: It was found that ceramic microstructure as well as the fabrication technique affects the selection surface treatment type. Also, Monobod Etch and Prime as a single step surface treatment produced clinically accepted and comparable results to that of HF treatment.

The influence of different shades and brands of resin-based luting agents on the final color of leucite-reinforced veneering ceramic

ObjectivesThis study aimed to evaluate the influence of different shades and brands of resin-based luting agents on the final color of a leucite-reinforced veneering ceramic. MethodsThis in-vitro study was done on 36 ceramic discs (IPS Empress I, 11 × 0.5 mm, A2 shade) and 36 cement disks (11 × 0.2 mm) made of Panavia SA Cement Plus (Kuraray Medical Inc.) and Choice2 (Bisco Inc., Schumburg) brands in translucent, universal A2, and opaque shades (n = 6 per each color in each resin cement brand). Color parameters (CIEL*a*b*) of ceramic specimens were calculated without and with each brand/shade of resin-based luting agents by using a spectrophotometer, and put into CIELab formula. The color differences (ΔE) between the two sets of measurements were calculated and analyzed with two-way ANOVA and Tukey’s post hoc test (α = 0.05). ResultsBoth the resin-based luting agent shade (P < 0.001) and brand (P = 0.023) significantly affected the color differences. ΔE values were significantly different between Panavia-opaque and Choice2-opaque (P < 0.001). No significant difference existed between ΔE of the two brands in A2 (P = 0.178) and translucent shades (P = 0.079). The ΔE values of Panavia-A2 was significantly different from the translucent and opaque shades of the same brand. Moreover, the ΔE of Choice2-translucent shade was significantly lower than that of A2 and opaque shades. The ΔE values were higher than the clinically-acceptable threshold in all groups (ΔE > 3.7) except for Choice2-translucent (ΔE = 3.37). ConclusionsThe final color of leucite-reinforced veneering ceramic can be affected by the same shades of resin-based luting agents from different brands and different shades of resin-based luting agents from the same brand.