IPS E-max CAD Research Articles

Comparison of three-dimensional digital technique with two-dimensional replica method for measuring marginal and internal fit of full coverage restorations.

PURPOSEThis study compared digital (reference point matching) and replica methods for measuring marginal and internal fit of full coverage restorations.MATERIALS AND METHODSA maxillary left first molar typodent was fixed on to an aluminum base and prepared to receive all-ceramic full coverage restoration. The model was scanned with an intraoral scanner (CEREC Omnicam, Sirona, York, PA, USA). Twelve crowns were fabricated from lithium disilicate blocks (IPS emax CAD, Ivoclar Vivadent) and then crystalized. Marginal and internal fit of each restoration was measured by two examiners using replica and a new digital three-dimensional technique. Reliability between the two methods and two examiners was assessed by correlation and Cronbach's Alpha coefficient (P<.05). A Bland-Altman assessment for agreement was used to compare the two methods.RESULTSBland-Altman assessment showed that the mean of difference for marginal, absolute marginal, and axial gap was respectively −1.04 µm, −41.9 µm, and −29.53 µm with limit of agreement (LOA) between −37.26 to 35.18 µm for marginal, −105.85 to 22.05 µm for absolute marginal and −80.52 to 22.02 µm for axial gap. Positive correlation for repeatability (P<.05) in determining marginal and internal gaps by the two examiners in both techniques was revealed. Reliability of both techniques in all sites of measurements was at least good (0.8 ≤ α < 0.9).CONCLUSIONBoth measuring techniques appeared highly reliable for evaluating fit of fixed dental restorations, while reference point matching provided higher values in axial and absolute marginal gap assessment.

Effect of Different Surface Finishing Procedures on the Color and Translucency of two CAD/CAM Monolithic Glass Ceramics

Purpose: The purpose of this study was to investigate the effects of different surface finishing procedures, storage solutions, and prophylactic polishing on the color and translucency parameters (TPs) of two machinable glass ceramics; lithium silicate glass-ceramic (Obsidian)and lithium disilicate reinforced glass-ceramic (IPS e-max CAD). Materials and Methods: Obsidian and e-max milling blocks were sectioned with a low speed cutting machineunder water cooling into square specimens (10×10×1 mm3)(N=60). The specimens were divided into 3 groups (n=10 each) according to the received surface treatment; finishing and polishing, glaze, and staining and glaze in accordance with manufacturers’ instructions. Then, each group was further subdivided into 2 storage subgroups, coffee and distilled water as a control (n =5 for each subgroup). Color and translucency values were measured in CIELAB color space with spectrophotometer at the initial stage, and following 18 days, and after fine-grit prophylactic polishing paste application. Color changes (ΔE) and translucency (ΔTPs) were calculated and statistically analyzed using One-way ANOVA for comparing surface treatment followed by Tukey’s pair-wise if showed significant. Student t-test was used within material type to show effect of staining. Multifactorial analysis of variance ANOVA was performed to detect significance between variables (material type, surface treatment, immersion solution and re-polish).Results: There was a statistically significant difference between the ΔE values of both immersion solutions as (p = water) for both ceramics tested. Obsidian and e-max, glaze procedure showed lower color change values than finishing and polishing and staining and glazing surface(p > 0.05) following coffee storage. It was found that re-polish decreased color change significantly for both tested ceramics. The translucency was affected according the monolithic CAD/CAM ceramic type. The translucency of the e-max was found to be higher than that of obsidian glass-ceramic. Colorant coffee solution decreased the translucency of both obsidian and e-max ceramics. According to the results of this study, mechanical polishing exhibited highest translucency than stained and glazed and glazed groups. The re-polishing procedure decreased translucency parameter non-significantly for both tested ceramics. Conclusions: Within the limitations of this study, the following conclusions could be drawn: Staining drinks as coffee had a negative effect on the color stability and translucency of both obsidian and e-max glass ceramic materials tested. Glaze procedure led to more color stability with respect to finishing and polishing and stained and glaze for both ceramics after 18 days coffee storage. Polishing paste led to a decrease in color changes for both ceramics tested. The translucency was affected according the monolithic CAD/CAM ceramic type. The translucency of the e-max lithium disilicate glass-ceramic was found to be higher than that of obsidian lithium silicate glass ceramic after different finishing procedure, after coffee storage and after re-polish. Finished and polished groups presented the highest translucency than stained and glazed and glazed for both ceramics tested. Re-polish decreased translucency parameters non-significantly for both tested ceramics.

Evaluation of Marginal and Internal Adaptation of Endocrowns Fabricated from Three Different CAD/CAM Materials.

This in vitro study aimed to compare the internal and marginal discrepancies of endocrowns fabricated from different ceramics before and after adjustment. Thirty-six endocrowns were fabricated from lithium disilicate (IPS e-max CAD), zirconia-reinforced lithium silicate (Suprinity), and polymer-infiltrated ceramic network (Enamic) using a CEREC intraoral scanner and milling unit. A reference point matching scan protocol was used to measure the endocrowns fit. The mixed ANOVA was used to analyze the data, and α=0.5 was considered as the significance level. There was no significant interaction between the fabrication materials and adjustment (P⟩0.05). Type of the materials did not change discrepancies at cavosurface, line angle, cavity wall, and pulpal floor (P⟩0.05). On the contrary, adjustment significantly decreased the discrepancies at all four sites (P⟨0.001). There were significant differences between every two sites before adjustment (P⟨0.001). After adjustment, except for cavosurface and cavity wall (P=0.058), the differences between other sites remained significant (P⟨0.001). IPS e-max CAD, Suprinity, and Enamic endocrowns were not significantly different regarding internal and marginal discrepancies. However, it is suggested that these materials be adjusted to fall in a clinically acceptable range to minimize the risk of caries and periodontal disease.

Marginal Gap Distance and Fracture Resistance of Lithium Disilicate and Zirconia-Reinforced Lithium Disilicate All-Ceramic Crowns Constructed With Two Different Processing TechniquesWith Two Different Processing Techniques

Statement of problem: The microstructure and processing methods used to produce any dental restoration might affect the final mechanical outcomes as well as the clinical success. Objectives: The purpose of this study was to evaluate the fracture resistance of lithium disilicate and zirconia reinforced lithium disilicate ceramic crowns constructed using two processing techniques after fatigue loading namely, CAD/CAM technique and pressing technique. The marginal integrity of the crowns was examined before and after fatigue loading. Methods: A total number of thirty-two freshly extracted maxillary first molars were collected. The teeth were chosen to be of similar bucco-lingual and mesiodistal dimensions. The teeth were mounted vertically into epoxy resin templates. Full coverage all-ceramic preparation was performed for all samples using a standardized technique. The prepared teeth were randomly divided into four equal groups (n=8) according to the all-ceramic materials and technique used for crown fabrication as follows: Group I: IPS e-max CAD(EC): eight prepared teeth were restored with machinable lithium disilicate glass ceramics. Group II: Celtra Duo(CD): eight prepared teeth were restored with machinable zirconia-reinforced lithium disilicate glass ceramics. Group III: IPS e-max Press (EP): eight prepared teeth were restored with pressable lithium disilicate glass ceramics. Group IV: Celtra Press (CP): eight prepared teeth were restored with pressable zirconia-reinforced lithium disilicate glass ceramics. The crowns were cemented using self-adhesive resin cement (Rely X Unicem). Vertical margin gap distance of all the crowns was measured using a stereomicroscope. Following vertical marginal gap distance measurements, the samples were subjected to fatigue cyclic loading for 60000 cycles which is equivalent to six months clinical service. The vertical marginal gap distance for all samples were subsequently remeasured after the fatigue loading testing. Fracture resistance test was done using universal testing machine. The fracture load was recorded in Newton. Data was collected, tabulated and statistically analyzed. Results: One-way ANOVA test for comparison between the fracture resistance of the four types of all-ceramic crowns revealed that there was a statistically significant difference between mean fracture resistance of different all ceramic materials and techniques used in this study (P-value <0.001). For the marginal gap distance either before or after fatigue cyclic loading; there was a statistically significant difference between the four all ceramic crowns used in this study.Conclusions: CAD/CAM techniques showed better fracture resistance values than pressable techniques, even if the same material was used. The addition of zirconia to lithium disilicate ceramics did not improve the fracture resistance of all ceramic crowns. Pressable processing techniques showed better vertical marginal gap distance than CAD/CAM techniques for both ceramic materials used. Cyclic loading resulted in significant increase in the vertical marginal gap distance for all ceramic crowns using different processing techniques.

Comparison of Bond Strength of Monolithic CAD-CAM Materials to Resin Cement Using Different Surface Treatment Methods

Objective: To compare the bond strength of monolithic CAD-CAM materials to resin cement using different surface treatment methods. Materials and Methods: Lithium disilicate glass ceramic (IPS e-max CAD), zirconia-reinforced lithium silicate ceramic (Vita Suprinity), resin nanoceramic (Lava Ultimate), and hybrid ceramic (Vita Enamic) were used. Five groups of CAD-CAM blocks were treated as follows: control (C), HF etching (HF), HF etching + silanization (HF + S), sandblasting (SB), and sandblasting + silanization (SB + S). After surface treatments, SEM analyses were conducted. Specimens were cemented with self-adhesive resin cement (Theracem) and stored in distilled water at 37°C for 24 h. Shear bond strength (SBS) was measured, and failure types were categorized. Results were analyzed using two-way ANOVA and the post-hoc Tukey test. Results: Statistical analysis revealed significant differences between SBS values obtained for different surface treatments and CAD-CAM block types ( P &lt; .001). Among the CAD-CAM materials, the highest SBS was reported in the HF + S group for Vita Enamic. Although IPS e.max CAD, Vita Suprinity, and Vita Enamic showed higher bond strength when treated with HF + S, Lava Ultimate has the highest bond strength value when treated with SB + S. Conclusions: The bond strength of CAD-CAM materials was influenced by surface treatment. Additionally, silanization significantly improved the bond strength of all materials except Lava Ultimate.

Microstructural, physical, and optical characterization of high-translucency zirconia ceramics

Statement of problemThe microstructural, physical, and optical properties of newly available highly-translucent zirconia ceramics have not been thoroughly investigated. PurposeThe purpose of this in vitro study was to evaluate the microstructural, physical, and optical properties of current zirconia ceramics with different degrees of translucency and to compare the optical properties with lithium disilicate glass-ceramic at different thicknesses. Material and methodsDisk-shaped specimens (N=108) were prepared from 3 different monolithic zirconia ceramics: VITA YZ HT (YZ-HT), VITA YZ ST (YZ-ST), and VITA YZ XT (YZ-XT) and lithium disilicate glass-ceramic (IPS e-max CAD LT [IPS]) with a diameter of 14 mm and 3 different thicknesses (0.5, 1.0, and 1.5 mm ±0.02 mm). The microstructural features (grain size, elemental composition, phase identifications, and quantifications), physical properties (Vickers hardness and fracture toughness), and optical properties (translucency parameter and contrast ratio) were investigated. Data were analyzed using 1-way ANOVA, followed by the post hoc Tukey tests or Kruskal-Wallis and Mann-Whitney U tests (α=.05). ResultsDifferences in grain size, phase assemblages, fracture toughness, translucency parameter, and contrast ratio were found to be significant (P<.05). The average grain size was different for the 3 zirconia specimens with the following order: YZ-XT>YZ-ST>YZ-HT. The fracture toughness of YZ-HT was higher than that of YZ-ST and YZ-XT (P<.05). IPS with 0.5-mm thickness had the highest TP followed by YZ-XT and YZ-ST. The CR values were in the range of 0.54 to 0.91 (YZ-HT), 0.43 to 0.61 (YZ-ST), 0.29 to 0.45 (YZ-XT), and 0.27 to 0.53 (IPS), and all decreased with an increase in thickness. ConclusionsBased on the results of the present study, the microstructural, physical, and optical properties of zirconia ceramics were affected by the changes in chemical composition and sintering parameters.

Evaluation of Marginal Accuracy and Color Stability of Lithium Disilicate Laminate Veneer Compared to Hybrid Ceramic Veneer

Purpose: The purpose of the current study was to evaluate marginal accuracy and color stability of lithium disilicate laminate veneer compared to hybrid ceramic veneer. Materials and Methods: Forty maxillary teeth were collected and prepared (but joint preparation) to receive a laminate veneer. They were equally sub grouped (n= 20) to receive 2 types of laminate veneers (IPS E-max CAD and vita enamic). The veneer was milled from the blocks in a CEREC 3 Machine. All veneers were cemented with resin cement. All samples had been subjected to 20000 thermal cycles which are equivalent twenty years of clinical use. Marginal gap were measured by using universal serial bus (USB) Digital microscope. Colors were measured using a reflective spectrophotometer. Marginal gap and color were measured pre and post thermo cycles. Data were tabulated and statistically analyzed. Results: For the marginal gap, the two tested materials demonstrated an acceptable value. Regarding the color stability there was color change for both groups after thermal cycling with higher mean values for Vita Enamic than E-max and that was statistically insignificant. Conclusion: The E-max veneers recorded less marginal accuracy and more color stability than Vita Enamic and they did not affected by thermo cycling.

Scanning electron microscope evaluation of the marginal gap and internal fit of additive versus subtractive fabrication techniques for posterior lithium disilicate crowns

Statement of the problem: The wide use of digital dentistry in fixed prosthodontics using 3D printers and CAD/CAM in fabricating crowns and partial fixed dental prosthesis created a need for more information about their marginal gap and internal fit.Purpose: This study aimed to evaluate the effect of fabrication technique using CAD/CAM manufactured and heat pressed lithium dislicate crowns made from milled wax and 3D printed resin patterns on their marginal gap and internal fit.Material & Methods: A total of 50 prepared mandibular first molar resin models were used and divided into two main groups according to their fabrication phase: Patterns group and fully fabricated crowns group. Patterns group was subdivided into milled wax patterns (W) (n=10) and 3D printed resin patterns (P) (n=10). Fully fabricated crowns group was subdivided according to fabrication technique of lithium disilicate crowns into: Machinable ceramics (M), using IPS e-max CAD blocks (n=10), Pressable ceramics (Pw), using IPS e-max press ingots following wax milling (n=10) and Pressable ceramics (Pp), using IPS e-max press ingots following 3D resin printing (n=10). All patterns and ceramic crowns were cemented with Rely-X self-adhesive resin cement. Marginal and internal adaptations were measured using SEM at 300 × magnification. Kruskal-Wallis and Wilcoxon signed-rank tests were applied to compare between the groups. Data were presented as median and range values. The significance level was set at P ≤ 0.05.Results: P group showed a significant higher median total marginal gap of 111.4 μm (80.8-139.7) than W group of 51.3 μm (45.1-57.8) before heat pressing. While M group showed the significant highest median marginal gap of 138.4 μm (83.4-191.8) and no significant difference between heat pressed groups (Pw and Pp) (P ≤ .05). Regarding changes after heat pressing, Pw group showed no significant decrease, while Pp group showed a significant decrease in median total marginal gap. For internal fit, there was no significant difference between the pattern groups (W and P) before heat pressing (P ≤ .05). After heat pressing, Pp group showed the significantly highest median gap of 195 μm (138.9-441.5) with no significant difference between M and Pw groups (P ≤ .05). Pw group showed a significant decrease in median gap, and Pp group showed no significant decrease after pressing (P ≤ .05). Conclusions: Heat pressed lithium disilicate glass ceramic crowns produced from CAD/CAM waxing or resin 3D printing techniques resulted in better marginal and fit accuracy than CAD/CAM. 3D printed resin patterns yielded internal fit values higher than other groups, but with promising clinical acceptability.Clinical implications: Both the additive and subtractive production for patterning phase before heat pressing allow clinical acceptability in terms of marginal and internal adaptation when a single unit posterior ceramic lithium disilicate crown is fabricated.

Physicochemical and morphological characterization of a glass ceramic treated with different ceramic primers and post-silanization protocols

ObjectiveEvaluate the effect of different ceramic primers and post-silanization protocols on physicochemical and morphological characteristics of a lithium disilicate glass ceramic. MethodsLithium disilicate ceramic (IPS e-max CAD) plaques (6 × 10 × 2 mm) were divided into 3 groups according to the ceramic primer used: (1) Silane (RelyX Ceramic Primer-RL); (2) Silane + MDP (Clearfil Ceramic Primer Plus-CP); (3) Self-etching ceramic primer (Monobond Etch and Prime-MB). Specimens from each group were distributed into 5 sub-groups according to post-silanization protocols: (a) Treated as recommended by the manufacturer (MR), (b) MR + Additional drying with air at room temperature for 30 s (RTA), (c) MR + additional drying with hot air for 30 s (HT), (d) MR + Surface rinsing with water at room temperature for 10 s and drying with air at room temperature for 30 s (WT), and (e) Specimens were not silanized (NS). Surface free energy (SFE) was determined using static contact angles measurements with water and diiodomethane. SFE data were submitted to Friedman followed by Wilcoxon post-hoc test (α = 0.05). Morphology was analyzed using scanning electron microscopy. Elemental composition and chemical interactions were determined with X-ray photoelectron spectroscopy analysis. ResultsRL presented the highest SFE (62.4 mN/m) followed by CP (59.7 mN/m). Post-silanization protocols resulted in similar SFE, but WT and HT induced the highest water contact angles when using CP and RL. CP modified ceramics’ surface morphology compared to the etched and RL treated groups. The presence of water was identified on CP treated specimen. All analyzed primers formed siloxane bonds with ceramic surface. SignificanceCeramic primers resulted in different surface free energy and morphology, but siloxane bonds were identified for all tested solutions. HT and WT protocols should be used with RL and CP primers. MB was not influenced by the different silanization protocols.

The critical bond strength of orthodontic brackets bonded to dental glass–ceramics

To evaluate the critical bond strength (σ) of ceramic and metal brackets to a lithium disilicate-based glass-ceramic. Two hundred and forty ceramic specimens (IPS e-max CAD) were randomly distributed in 12 experimental groups (n = 20). Two ceramic brackets (monocrystalline, BCm; and polycrystalline, BCp) and a metal bracket (BM) were bonded to glass-ceramic specimens after one of the following surface treatments: HF-hydrofluoric acid applied for 60s; S-silane applied for 3min; HFS-HF followed by S; and MDP-application of an adhesive containing a phosphate monomer (MDP). All brackets were bonded to the treated glass-ceramic using a resin cement, stored in 37°C water for 48h before shear bond strength testing. Optical (OM) and scanning electron (SEM) microscopies were used for fractographic analysis. Data was statistically analyzed using Kruskal-Wallis and Student-Newman-Keuls (α = 0.05). BCm bonded to glass-ceramic treated with either HFS or HF showed the highest median σ values, respectively, 10.5MPa and 8.5MPa. In contrast, the BCp bonded to glass-ceramic treated with MDP showed the lowest median σ value (0.8MPa), which was not statistically different from other MDP-treated groups. The failure mode was governed by the glass-ceramic surface treatment, not by the bracket type. Quantitative (σ values) and qualitative (fracture mode) data suggested a minimum of 5MPa for brackets bonded to glass-ceramic, which is the lower critical limit bond strength for a comprehensive orthodontic treatment. Bonding brackets to glass-ceramic requires micromechanical retention.

Evaluation of patient satisfaction and shade matching of Vita Suprinity versus lithium disilicate (E-max) ceramic crowns in the esthetic zone: a randomized controlled clinical trial

Background: Optical impairments of teeth in the esthetic zone constitute a problem for many dentists and patients as several studies concluded that patients were dissatisfied of their dental appearance because of their restorations' color. The purpose of this study was to assess patient satisfaction combined with shade matching of VITA SUPRINITY versus lithium disilicate (IPS e-max CAD) all-ceramic crowns in esthetic zone. Methods: 26 patients with teeth problems indicated for full coverage restoration on one tooth in the esthetic zone (from upper central incisor to 1st premolar) were randomized into 2 equal groups (n=13) for which different CAD-CAM ceramic materials were used; (VITA SUPRINITY) a zirconia reinforced lithium silicate ceramic and (IPS e.max CAD) lithium disilicate glass ceramic. The crowns were fabricated to match the shade of the contra-lateral/ adjacent tooth and assessed using the modified USPHS criteria. Also patient satisfaction was assessed. The data obtained by evaluating each assessment criteria were statistically analyzed using the Chi-square test that was performed in categorical data. Results: According to the modified USPHS criteria, 100% of the patients were Alpha score with 0% for Bravo, Charlie and Delta scores in both groups. While according to the visual analogue scale (VAS), 100% of the patients were satisfied while 0% were dissatisfied by the restoration in both groups. Conclusions: The results for both materials in terms of patient satisfaction and shade matching were Alpha. This indicated that both materials are clinically accepted to be used as full coverage restorations for excellent esthetic outcome. Registration: NCT0284611.

In vivo wear determination of novel CAD/CAM ceramic crowns by using 3D alignment.

PURPOSETo determine wear amount of single molar crowns, made from four different restoratives, and opposing natural teeth through computerized fabrication techniques using 3D image alignment.MATERIALS AND METHODSA total of 24 single crowns (N = 24 patients, age range: 18 – 50) were made from lithium disilicate (IPS E-max CAD), lithium silicate and zirconia based (Vita Suprinity CAD), resin matrix ceramic material (Cerasmart, GC), and dual matrix (Vita Enamic CAD) blocks. After digital impressions (Cerec 3D Bluecam, DentsplySirona), the crowns were designed and manufactured (Cerec 3, DentsplySirona). A dual-curing resin cement was used for cementation (Variolink Esthetic DC, Ivoclar). Then, measurement and recording of crowns and the opposing enamel surfaces with the intraoral scanner were made as well as at the third and sixth month follow-ups. All measurements were superimposed with a software (David-Laserscanner, V3.10.4). Volume loss due to wear was calculated from baseline to follow-up periods with Siemens Unigraphics NX 10 software. Statistical analysis was accomplished by Repeated Measures for ANOVA (SPSS 21) at = .05 significance level.RESULTSAfter 6 months, insignificant differences of the glass matrix and resin matrix materials for restoration/enamel wear were observed (P>.05). While there were no significant differences between the glass matrix groups (P>.05), significant differences between the resin matrix group materials (P<.05) were obtained. Although Cerasmart and Enamic were both resin matrix based, they exhibited different wear characteristics.CONCLUSIONGlass matrix materials showed less wear both on their own and opposing enamel surfaces than resin matrix ceramic materials.

Physico-mechanical properties of resin cement light cured through different ceramic spacers.

The purpose of this in vitro study was to compare the micro hardness, color stability/ΔE, and degree of conversion/DC of a resin cement light cured through different ceramic spacers. Lithium-disilicate ceramic samples were obtained from IPS E-max CAD blocks (HT A1) and IPS in-Ceram (transparent neutral); and divided in 7 groups (n = 8 for each test): CTR/control group; 06 M/0.6 mm monolithic; 12 M/1.2 mm monolithic; 20 M/2.0 mm monolithic; 06B/0.4 + 0.2 mm bilayered; 12B/1.0 + 0.2 mm bilayered; 20B/1.8 + 0.2 mm bilayered. The resin cement (Variolink veneer) was light cured through the ceramic spacers. The resin cement samples were evaluated for ΔE using a spectrophotometer after 24 h, 7days and after aging (24 h in water at 60 °C). Knoop microhardness and DC tests were conducted immediately after light curing, after 24 h and 7days. All experimental groups showed similar microhardness values, although being lower than CTR group. Similar results were observed after 7days. ΔE was similar between all groups after 24 h (except for 12B and 20B), and increased for all groups after 7days and after artificial aging, especially for thicker and bilayer groups. Only 06 M showed values similar to CTR group. DC values were similar to all groups immediately after light curing, increasing after 24 h and 7days. After 7days, only group 20B showed lower DC than CTR group. A tendency of higher DC could be observed for monolithic and thinner ceramics. All test results showed strong correlation (0.9987). Ceramic interposition can reduce mechanical and physical properties of resin cements, especially with thicker and bilayered ceramics. Group 06 M showed the best ΔE overtime.

Comparative Study between Resin Nano Ceramic and CAD/CAM Ceramic Regarding Their Fracture Resistance, Microtensile Bond Strength and Fatigue Resistance

Purpose: In an attempt to improve the mechanical properties, industriallyCAD/CAM ceramics blocks have been introduced to dentistry. This study was directed to investigate the influence of the material thickness on the fracture resistance ofCAD/CAM Resin Ceramic and CAD/CAM Ceramic and asses the fatigue resistance of class II mesio-occlusal-distal (MOD) inlays of both materials and compare their micro-tensile bond strength (μTBS) after cementation by two different adhesive resin cements. Materials and Methods: A total of 70 specimens were fabricated. The specimens were divided according to the material used into two main groups (n= 35). Group 1 specimens were fabricated from CAD/CAM Resin Ceramic (Vita Enamic), whereas Group 2 specimens were fabricated from Lithium disilicate glass ceramic (IPS e-max CAD). Specimens of each group were further subdivided into 3 subgroups according to type of testing (microtensile bond strength test, fracture resistance and fatigue resistance tests). Specimens of subgroup of microtensile bond strength test (n=40) were further subdivided into 2 divisions (n=20) according to type of surface treatment (control and sandblasting). Then each division was further subdivided into 2 subdivisions (n=10) according to type of cement used (Rely X Ultimate and multilink N). Furthermore, subgroup of fracture resistance test (n=20) was further divided into 2 division (n=10) according to thickness (0.5 mm and 3 mm). Two-way analysis of variance ANOVA test and three-way analysis of variance ANOVA test of significance were done for comparing variables. Results: For microtensile bond strength, it was found that the highest μ-tensile bond strength value was recorded for Multilink N control subgroup (54.07±7.9 MPa), while the lowest μ-tensile bond strength mean values was for Rely X Ultimate sandblasted subgroup (37.12±2.5 MPa) and IPS e-max CAD. Results revealed that the highest μ-tensile bond strength mean value was recorded for Rely X Ultimate

Investigation the Effect of Restorations Fabricated with CAD/CAM Technology, the Heat-Press Technique, and Type of Resin Cement on Marginal and Internal Adaptation of All Ceramic Crowns

Statement of the problem; the use of pressable and CAD/CAM ceramics have been lately frequently used in fixed prosthodontics. However, information about their marginal fit and internal adaptation are is little.Purpose: Marginal adaptation and internal adaptation are an important factor affecting the longevity of all ceramic restorations, so the purpose of the study was to evaluate the effect of restorations fabricated with CAD/CAM technology, the heat-press technique ceramic and luting agent on the Marginal Fit and Internal Adaptation of all Ceramic crowns.Materials & methods: A total of 20 mandibular Second premolars teeth were used in this study and divided into two groups according to technique of fabrication of ceramic crowns as follow: Machinable ceramics (M). IPS E-max CAD blocks have used for fabrication of ceramic crowns. (n=10), Pressable ceramics (P). IPS E-max press ingots have used for fabrication of ceramic crowns. (n=10).Each group is divided into two subgroups according to the type of resin cement used as follow: Group T: Ceramic crowns are cemented with total etch Cement-it resin cement (n=5). Group S: Ceramic crowns are cemented with Rely-x self-adhesive resin cement (n=5). A silicone replica was obtained to measure marginal and internal adaptation of each all-ceramic crown before luting, and they were sectioned vertically in mesiodistal direction. Marginal and internal adaptations were measured using computerized light microscope at 100 × magnification. Data were presented as mean and standard deviation (SD) values. Regression model with repeated measures Analysis of Variance two ways (ANOVA) was used in testing significance for the effect of ceramic type and cement type.Results: related to marginal gap, it was found that press group recorded statistically significant (P 0.05) higher (54.77± 0.8 μm) than total etch cement (50.3± 5.88 μm).while related to internal adaptation, totally it was found that CAD group recorded statistically significant (P<0.05) higher internal gap mean value (87.45 ± 15.4 μm) than press group (36.64± 5.15 μm) and it was found that internal gap mean value of total etch cement was statistically significant (P<0.05) higher (67.24± 11.14 μm) than self-adhesive cement (56.85± 9.4 μm).Conclusion: Within the limitation of this study, The CAD group recorded statistically significant high vertical marginal fit than press group. The cement type has no effect on the marginal fit. The press group recorded statistically significant high internal fit than CAD group.

INVESTIGATION THE EFFECT OF RESTORATIONS FABRICATED WITH CAD/CAM TECHNOLOGY, THE HEAT-PRESS TECHNIQUE, AND TYPE OF RESIN CEMENT ON MARGINAL AND INTERNAL ADAPTATION OF ALL CERAMIC CROWNS

Statement of the problem; the use of pressable and CAD/CAM ceramics have been lately frequently used in fixed prosthodontics. However, information about their marginal fit and internal adaptation are is little.Purpose: Marginal adaptation and internal adaptation are an important factor affecting the longevity of all ceramic restorations, so the purpose of the study was to evaluate the effect of restorations fabricated with CAD/CAM technology, the heat-press technique ceramic and luting agent on the Marginal Fit and Internal Adaptation of all Ceramic crowns.Materials & methods: A total of 20 mandibular Second premolars teeth were used in this study and divided into two groups according to technique of fabrication of ceramic crowns as follow: Machinable ceramics (M). IPS E-max CAD blocks have used for fabrication of ceramic crowns. (n=10), Pressable ceramics (P). IPS E-max press ingots have used for fabrication of ceramic crowns. (n=10).Each group is divided into two subgroups according to the type of resin cement used as follow: Group T: Ceramic crowns are cemented with total etch Cement-it resin cement (n=5). Group S: Ceramic crowns are cemented with Rely-x self-adhesive resin cement (n=5). A silicone replica was obtained to measure marginal and internal adaptation of each all-ceramic crown before luting, and they were sectioned vertically in mesiodistal direction. Marginal and internal adaptations were measured using computerized light microscope at 100 × magnification. Data were presented as mean and standard deviation (SD) values. Regression model with repeated measures Analysis of Variance two ways (ANOVA) was used in testing significance for the effect of ceramic type and cement type.Results: related to marginal gap, it was found that press group recorded statistically significant (P 0.05) higher (54.77± 0.8 μm) than total etch cement (50.3± 5.88 μm).while related to internal adaptation, totally it was found that CAD group recorded statistically significant (P<0.05) higher internal gap mean value (87.45 ± 15.4 μm) than press group (36.64± 5.15 μm) and it was found that internal gap mean value of total etch cement was statistically significant (P<0.05) higher (67.24± 11.14 μm) than self-adhesive cement (56.85± 9.4 μm).Conclusion: Within the limitation of this study, The CAD group recorded statistically significant high vertical marginal fit than press group. The cement type has no effect on the marginal fit. The press group recorded statistically significant high internal fit than CAD group.

Fracture Resistance of Endodontically Treated Teeth Restored with Lithium Disilicate Crowns Retained with Fiber Posts Compared to Lithium Disilicate and Cerasmart Endocrowns: In Vitro Study

Purpose: The purpose of this in vitro study was to compare the effect of endocrowns and glass fiber postretained crowns on the fracture resistance of endodontically treated maxillary premolars made of different ceramics materials. Materials and Methods: Thirty sound maxillary premolars were endodontically treated. They were randomly assigned into 3 groups (n=10), in which, teeth were prepared to receive all- ceramic restorations. GP: fiber post and resin core and ferrule with all-ceramic (IPS E-max CAD, Ivoclar-Vivadent) conventional crown. GE: Endocrown with butt joint finish line design made of (IPS E-max CAD, Ivoclar-Vivadent). GC: Endocrown with butt joint finish line design made of hybrid nanoceramic (CERASMART, GC Dental, USA). The lithium disilicate (IPS E-max press, Ivoclar-Vivadent) and hybrid nanoceramic (CERASMART, GC Dental, USA) all-ceramic restorations were made by CAD/CAM system (CEREC MC XL SW 4.0) and adhesively cemented with dual-cure resin cement (BisCem Bisco, Inc, USA). Specimens were mounted in a universal testing machine (Model 3345; Instron Industrial Products, Norwood, MA, USA). Each specimen was loaded to failure at a crosshead speed of 5.0 mm / min. Mode of failure was also examined. Data were analyzed using one way analysis of variance (ANOVA) and Tukey’s post hoc significance difference tests. Differences were considered significant at P<0.05. Results: One way ANOVA test showed that group (GC) recorded statistically significant (p 0.05) difference between GP and GC groups. Conclusions: Within the limitations of this study, all fracture resistance loads obtained in this study were far beyond the maximum masticatory forces and the presence of hybrid nanoceramic increased the fracture resistance of endodontically treated maxillary premolars restored with endocrown than those restored with lithium disilicate endocrowns, in failure mode hybrid nanoceramic showed favorable fracture pattern than lithium disilicate.

Bonding to silicate ceramics: Conventional technique compared with a simplified technique.

BackgroundSilicate ceramic bonding is carried out by acid-etching with hydrofluoric acid (HF) followed by an application of silane. By replacing HF with ammonium polyfluoride, contained in the same flask as the silane, the number of steps in this clinical procedure, can be reduced, while maintaining bond strength values, and reducing toxicity. A shear bond test was performed to compare the conventional and the simplified surface treatment techniques.Material and Methods Twenty ceramic samples were fabricated from IPS emax CAD® ceramic (Ivoclar Vivadent) and divided into two groups (G1 and G2) (n=10). The conventional technique was applied to G1 samples, and the simplified technique to G2 samples. A resin cement cylinder was bonded to each sample. Afterwards, samples underwent shear bond strength testing in a universal test machine.Results G1 obtained 26.53±6.33 MPa and G2 23.52±8.41 MPa, without statistically significant differences between the two groups.Conclusions Monobond Etch&Prime appears to obtain equivalent results in terms of bond strength while simplifying the technique. Further investigation is required to corroborate these preliminary findings. Key words:Shear bond strength, surface treatment, bonding to ceramic, hydrofluoric acid, ammonium polyfluoride.

EFFICACY OF INCISAL PREPARATION DESIGNS ON THE FRACTURE RESISTANCE OF TWO CAD/CAM LAMINATE VENEERS

Statement of problem: Mechanical properties are cardinal for the long-term clinical success of laminate veneer restorations. The most common failure is fracture and debonding, in which unfavorable occlusion and articulation play an important role. Nonetheless, the effect of different incisal preparations on the behavior of veneers remains controversial.Objective: The purpose of this study was to evaluate the fracture load of two different CAD/CAM laminate veneer materials: resin nano-ceramic [lava ultimate] and lithium disilicate glass ceramic [IPS e-max CAD], with two different incisal preparation designs [butt-Joint and incisal overlap]; using both in-vitro and finite element analysis studies. Materials and Methods: A total of 20 maxillary central incisors were used in this study. The samples were divided into two main groups (n=10), according to the CAD/CAM material used. Ten laminate restorations were constructed for each group following the manufacturer’s directions with the two preparation designs (5 samples each), then cemented on their corresponding teeth. Fracture load was recorded for each specimen using the universal testing machine. Meanwhile, Finite element analysis study was performed to assess the in-vitro observations. Results: The results revealed that incisal overlap design with Lava ultimate laminate veneers recorded the highest mean fracture strength value (395 ±37.18 N). This was supported by the finite element results that showed that the incisal overlap design with lava ultimate laminate veneers had the lowest Von Mises stress (30.75 MPa). Conclusions: Within the limitations of the present study, it was concluded that the butt-joint and incisal overlap designs demonstrated different mechanical behaviors with regard to the two different restorative materials. The incisal overlap design tolerated stresses better than the butt-joint design with both materials. Also, the incisal overlap design with resin nano-ceramic laminate veneers had the best stress distribution. Nevertheless, both types of CAD/CAM materials and different incisal preparation designs used could be considered strong enough to withstand the average anterior masticatory biting forces.

Blue-Light Transmittance of Esthetic Monolithic CAD/CAM Materials With Respect to Their Composition, Thickness, and Curing Conditions.

Determining the amount of blue light (360-540nm) passing through nine monolithic computer-aided design/computer-aided manufacturing (CAD/CAM) materials depends on material thickness, initial irradiance, and the distance between the curing unit and the specimen's surface. A total of 180 specimens of two thicknesses (1 mm and 2 mm, n=10/subgroup) were fabricated from TelioCAD, VITA CAD-Temp (VCT), experimental nanocomposite, LAVA Ultimate (LU), VITA ENAMIC (VE), VITA MarkII (VM), IPS EmpressCAD (IEC), IPS e.maxCAD (IEM), and CELTRA DUO (CD). The irradiance passing through the CAD/CAM materials and thicknesses was measured using a light-emitting-diode curing unit with standard-power, high-power, and plasma modes by means of a USB4000 spectrometer. The curing unit was placed directly on the specimen's surface at 2- and 4-mm distances from the specimen's surface. Data were analyzed using a multivariate analysis and one-way analysis of variance with the post hoc Scheffé test (p<0.05). The highest transmitted irradiance was measured for VM and LU, followed by VCT and IEC, while the lowest values showed VE, followed by IEM and CD. The highest transmitted irradiance was recorded by exposing the material to the plasma mode, followed by the high- and standard-power modes. The measured irradiance was decreased by increasing the specimen's thickness from 1 to 2 mm. Fewer differences were measured when the curing unit was placed at 0 or 2 mm from the specimen's surface, and the irradiance passing through the specimens was lower at a distance of 4 mm.