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Objectives To test the tensile bond strength (TBS) between two self-adhesive resin composite cements and PEEK after helium plasma treatment and used glycine as a potential coupling agent incorporated in different adhesives. Methods In summary, 896 air-abraded PEEK specimens were fabricated. Half of the specimens were treated with cold active inert helium plasma and the other half were left non-treated. Both groups were then split in two groups: In group 1 ( n = 256), 64 specimens were pre-treated with: (a) soft-liner liquid, (b) visio.link, (c) Ambarino P60 and (d) no pre-treatment (control), respectively. In group 2 ( n = 192), specimens were conditioned accordingly, but the adhesive materials were modified by including a commercially available glycine (Air-Flow PERIO). PEEK specimens were then luted using either RelyX Unicem or Clearfil SA Cement and TBS was measured initially and after 14 days water storage combined with 10’000 thermal cycles (16 specimens/subgroup). Fracture type analysis was performed. For statistical analyses Kolmogorov–Smirnov, Shapiro–Wilk tests, 1-, 4-way ANOVA (post hoc: Scheffe), and t -test were used ( p Results Helium plasma pre-treatment without glycine showed no impact on initial TBS ( p > 0.348). In contrast, a combination between glycine application and Softline/Ambarino P60 allowed for significantly higher initial TBS was measured after helium plasma treatment ( p = 0.001). However, this effect was no evident after thermo-cycling. All groups conditioned with visio.link showed the highest TBS values. Significance The introduction of amine groups by simple provision of amino acids in the form of glycine can improve the bond strength after helium plasma treatment using different adhesive materials. However, using this simple approach, the method cannot withstand thermal challenge yet.

To assess the retention force between primary and secondary PEEK crowns made by different fabrication methods. Primary crowns with different tapers (0°, 1°, and 2°) were fabricated and secondary crowns that were either milled from breCam BioHPP blanks, pressed from pellets (BioHPP Pellet) or granules (BioHPP Granulat) were produced. Each specimen was measured 20 times in a pulloff-test and results were analyzed using 2-/1-way ANOVA and linear regression analyses (p

Computer aided design/computer aided manufacturing (CAD/CAM) polymers for long-term dental restorations benefit from enhanced mechanical properties. However, the quantification of their bonding properties on teeth is lacking. Therefore, the aim of this study was to determine the retention strength (RS) of differently pretreated new developed polymethylmethacrylate/ urethanedimethacrylate-based CAD/CAM polymer bonded on dentin. In summary, 120 human caries-free molars were prepared, and polymeric crowns were milled and pretreated (n = 20): visio.link (VL), Scotchbond Universal (SU), Monobond Plus/Heliobond (MH), Margin Bond (MB), Margin Bond mixed with acetone (1:1) (MBA) or not pretreated (CG). Half of the specimens were cemented using Variolink II and the other half with RelyX Ultimate. Specimens were stored for 24 h in distilled water and thermal cycled (5000 ×, 5 °C/55 °C). The retention load was measured and failure types were defined. RS was calculated and analyzed using both two- and one-way ANOVA with a post-hoc Scheffé-test, unpaired t-test, Kaplan–Meier with Breslow–Gehan test and chi-squared test (p &lt, 0.05). Crowns bonded using RelyX Ultimate showed higher RS than those bonded using Variolink II. The pretreatment showed no impact on the RS. However, survival analysis within Variolink II found an impact of pretreatment. The median RS for MH was the lowest and statistically different from MB, MBA and CG. For Variolink II MH had the poorest survival as the estimated cumulative failure function of the debonded crown increased very quickly with increasing TBS. Within the RelyX Ultimate groups, no significant differences were determined. The newly developed CAD/CAM polymer showed the highest bonding properties after cementation using RelyX Ultimate.

To investigate the retention forces of differently fabricated secondary crowns made of Co-Cr alloy and electroforming secondary crowns considering different taper angles. Cobalt-chromium primary crowns with 0°, 1° and 2° taper angles were fabricated. Secondary crowns were made either by i.) a milling and sintering, ii.) casting or iii.) electro-forming process. Pull-off tests were performed and data were analyzed by parametric statistics (p

Objective To assess the efficiency of intraoral repair kits on the tensile bond strength (TBS) of resin composites (RCs) to aged RC substrates. Methods 840 aged (six months, 37 °C, distilled water) RC substrates (Tetric EvoCeram) were air-abraded (CoJet) with and without following phosphoric acid contamination or treated with silicon carbide (SiC) grinding paper. Seven repair kits were used as intermediate agents (Embrace First-Coat, CLEARFIL CERAMIC PRIMER, Tokuso Ceramic Primer, Monobond Plus+Heliobond; Scotchbond Universal, One Coat Bond and visio.link) for conditioning. Specimens were repaired using two direct RCs (Clearfil Majesty ES2 and Clearfil Majesty Posterior), stored in distilled water (37 °C, 24 h) and thermal aged (5 °C/55 °C, 10,000 cycles). The cohesive strength of the repair RCs ( N =40) served as control and was determined by applying the RCs on the fresh polymerized substrates, followed by thermal-aging procedure. TBS and failure types were determined and evaluated with three-/one-way ANOVA, and chi-square test ( p Results The highest influence on the TBS was exerted by the intermediate agent (repair kit) (partial eta squared η P ²=0.320, p P ²=0.017, p P ²=0.015, p =0.003) were significant but low. Except for Embrace First Coat and Tokuso Ceramic Primer, phosphoric acid contamination after air-abrasion maintains the TBS. Conclusions Air-abrasion induced superior TBS compared with grinding the surface with SiC paper prior to repair. Tested universal adhesives as well as the combination between a universal primer and an adhesive were in-vitro efficient intermediate agents for repairing aged RCs.

Statement of problem Dual-polymerized luting composite resin cements would benefit from enhanced irradiance transmitted through a ceramic restoration. A quantification of the amount of transmitted light through translucent zirconia is lacking. Purpose The purpose of this study was to evaluate the amount of light (360 to 540 nm) passing through translucent and conventional zirconia and a glass ceramic with respect to material thickness and different polymerizing modes. Material and methods Six translucent and a conventional zirconia (negative control) and a glass ceramic (positive control) were considered. Ten specimens of each material and thickness (.5, 1, 1.5, 2, 2.5, 3 mm) were fabricated (n=480). Zirconia materials were sintered according to manufacturers' instructions. The irradiance passing the different ceramics and thicknesses was measured with a violet-blue LED polymerizing unit in 3 polymerizing modes (plasma, high, and standard power mode) with a USB4000 Spectrometer. The polymerizing unit was placed directly on the specimen's surface. Data were analyzed with one and multivariate analysis and the Pearson correlation analysis (α=.05). Results In all materials, the translucency and its rate decreased exponentially according to the specimen thickness. The highest influence on the measured irradiance passing through translucent zirconia was exerted by ceramic thickness ( P P ²]=.998), closely followed by polymerizing mode (η P ²=.973), while the effect of the material ( P =.03, η P ²=.06) and mean grain size ( P =.029, η P ²=.027) was significant but low. Conclusions Zirconia was less translucent than the glass ceramic, but the translucency decreased more slowly with material thickness, thus approaching the translucency of glass ceramics at a specimen thicknesses of 2.5 to 3 mm.

Objectives Comparison of estimation of the two-parameter Weibull distribution by two least squares (LS) methods with interchanged axes. Investigation of the influence of plotting positions and sample size. Derivation of 95% confidence intervals (95%CI) for Weibull parameters applicable in the context of LS estimation. Preparation of a free available Excel template for computation of point estimates and 95%CI for Weibull modulus ( m ) and characteristic strength ( s ). Methods Monte Carlo simulation covering a wide range of Weibull parameters and sample sizes. Mathematical derivation of formulae for computation of 95%CI according to a Menon-type approach for both m and s . Empirical proof that the practically observed coverage agrees with the nominal one of 95%. Results Relative and absolute performance of LS estimators depended on sample size, plotting positions and parameter to be estimated. For most situations they outperformed the corresponding Maximum Likelihood (ML) estimator in terms of bias, while precision was almost the same. Naive Wald-type 95%CI based on standard errors of LS regression coefficients did not reach targeted coverage. An easy-to-apply alternative based on asymptotic standard errors (Menon 95%CI) resulted in excellent coverage. Conclusion Accuracy of the LS methods for Weibull modulus and characteristic strength essentially depend on plotting position and sample size. Large sample sizes ( n ≥ 30) support a credible Weibull parameters estimation. An important complement of the point estimates of Weibull parameters is provided by the Menon 95%CI. A free available Excel template considerably facilitating computation of point and interval estimates of Weibull parameters is provided.

This study investigated the influence of different surface treatments on fracture load (FL) of canine crowns fabricated from two different pressable lithium-disilicate ceramics: A (HS10PC, estetic ceram, n=180) and B (IPS e.max Press, IvoclarVivadent, n=120). The standardized specimens were divided into groups of six different surface treatments and two glazing temperatures. A-group specimens were additionally assigned two glazing pastes with various thermal expansion coefficients (TEC). FL was measured and TECs were determined. Data were analyzed using three/one-way ANOVA followed by post-hoc Scheffe's test. B showed comparable or higher FL than A (B: 503-876 N; A: 375-734 N). Lithium-disilicate crowns show higher FL when not grinded but only polished or glazed. Glazing pastes affected FL depending on their TECs, firing temperature and crown treatment. TEC of A and B was 10 ppm/K, glazing pastes for A presented TECs of 7.5 ppm/K and 10 ppm/K and for B of 9 ppm/K.

To investigate discoloration reduction and changes of surface properties of a CAD/CAM resin composite after 14 days´ storage in red wine and polishing with nine different prophylactic polishing pastes (PPPs). Rectangular discs (N = 172) were fabricated and polished (P4000) using GC Cerasmart (GC Europe) to investigate different polishing protocols with 1–4 related descending PPPs (22 in total): Cleanic/CLE-Kerr, CleanJoy/CLJ-Voco, Clean Polish/Super Polish/SPO-Kerr, Clinpro Prophy Paste/CPP-3M, Detartrine/DET-Septodont, Nupro/NUP-Dentsply Sirona, Prophy Paste CCS/CCS-Directa, Proxyt/PXT-Ivoclar Vivadent, and Zircate/ZIR Prophy Paste-Dentsply Sirona. Surface properties (roughness values (RV)/Ra, Rz, Rv, surface free energy (SFE), surface gloss (G), and discoloration (ΔE)) were analyzed before and after storage and additional polishing. Data were examined using Kolmogorov-Smirnov test, three-way ANOVA followed by Tukey-B post hoc, Mann-Whitney U, and Kruskal-Wallis H tests (α

Polymeric material for 3-dimensional printing can be used to fabricate occlusal devices. However, information about fracture resistance and wear is scarce.The purpose of this in vitro study was to investigate the fracture resistance and 2-body wear of 3-dimensional-printed (3DP) (FotoDent splint; Dreve Dentamid GmbH), milled polymethylmethacrylate (CAM) (Temp Basic; Transpa 95H16, Zirkonzahn GmbH), and conventionally fabricated polymethylmethacrylate (CAST) (Castdon; Dreve Dentamid GmbH) occlusal devices.A total of 96 occlusal devices were prepared according to the 3 different manufacturing techniques 3DP, CAM, and CAST (n=32). For each manufacturing technique, specimens were further divided into initial fracture resistance tests (n=16) and artificial aging in the mastication simulator (50 N, 37°C) with 2-body wear followed by fracture resistance tests (n=16). The fracture resistance was determined using a universal testing machine (1 mm/min). The wear was measured after 20 000 and 120 000 mastication cycles with the replica technique, mapped with a laser scanner, and quantified in R software. Data were analyzed using a 2-way ANOVA followed by a 1-way ANOVA with Scheffé or Games-Howell post hoc tests, repeated measures ANOVA with corrected Greenhouse-Geisser P values, and the Levene, Mann-Whitney, and paired t tests (α=.05).CAM presented higher initial fracture resistance than 3DP or CAST (P.001). After mastication simulation, CAM followed by 3DP showed higher fracture resistance than CAST (P.001). Mastication simulation decreased the fracture resistance for CAM and CAST (P.001) but not for 3DP (P=.78). Three-dimensional-printed occlusal devices showed the highest material volume loss, followed by CAM and the lowest in CAST (P.001).Three-dimensional-printed occlusal devices showed lower wear resistance and lower fracture resistance than those milled or conventionally fabricated. Therefore, only short-term application in the mouth is recommended. Further developments of occlusal device material for 3-dimensional printing are necessary.

To investigate the impact of pretreatment and conditioning on bonding behavior of polyetherketoneketone (PEKK) to methylmethacrylate(MMA)- and dimethacrylate(DMA)-based polymers.1200 PEKK substrates (Pekkton ivory) were fabricated, air abraded (110 µm, Al2O3) and divided into 8 pretreatment groups as follows: 1. Visio.link (VL); 2. VL+ opaquer; 3. Pekk Bond (PB); 4. PB + opaquer; 5. plasma; 6. plasma + opaquer; 7. plasma + VL+ opaquer; 8. plasma + PB + opaquer. A low-density cold oxygen plasma was used to treat specimens in groups 5-8. All pretreated PEKK substrates were bonded with either MMA-based polymers (denture acrylic: "Anaxdent acryline") or DMA-based polymers (veneering composites: flowable "Anaxdent dentin flow" or packable "Anaxdent dentin paste"). On denture acrylic, the anaxgum opaquer paste was applied, and on veneering composites, the anaxblend opaquer paste. All specimens were stored in water for 24 h at 37°C, and 20 specimens of each subgroup were additionally thermocycled (5°C/55°C, 10,000x). Tensile bond strength (TBS) was measured and analyzed with the general linear model analysis, Kaplan-Meier survival estimates, and Breslow-Gehan tests.The combination of plasma and VL showed the highest TBS results, followed by VL and the combination of plasma and PB. The lowest TBS was observed among PEKK specimens treated with plasma and without pretreatment, followed by specimens conditioned with PB. The application of an opaquer layer increased the TBS. Bonding to PEKK with MMA-based polymers showed higher TBS results than with DMA-based polymers. Among DMA-based polymers, the flowable polymer bonded significantly better to PEKK compared to paste polymer. After thermocycling, the TBS decreased.Sufficient bonding to PEKK is possible when plasma treatment is used in combination with the tested adhesives and an opaquer layer.

WOS:000448767900010 PubMed: 29703672 Statement of problem. The color of resin cements and computer-aided-design and computeraided-manufacturing (CAD-CAM) restorations may change with aging. Purpose. The purpose of this in vitro study was to analyze the influence of thermocycling on the color of CAD-CAM materials with underlying resin cement. . Material and methods. Seven different CAD-CAM materials, composite resins and glass-ceramics were cut into 0.7-mm and 1.2-mm thicknesses (n=10) and cemented with a dual-polymerizing resin cement, a light-polymerizing resin cement, and a preheated composite resin (N=420). Color values were measured by using spectrophotometry. Specimens were subjected to thermocycling (5 degrees C and 55 degrees C; 5000 cycles). The measured color difference (Delta E) data were analyzed by using descriptive statistics. Normality of data distribution was tested by using the Kolmogorov-Smirnov test. Three-way and 1-way ANOVA followed by the Scheffe post hoc test and unpaired 2-sample Student t test were computed to determine the significant differences among the tested parameters (alpha=.05). Results. Delta E values were significantly influenced by the CAD-CAM material (eta(2)(p)=0.85, P

This article presents the historical development of the different generations of zirconia and their range of indications, from veneered to monolithic zirconia restorations. While Part I concentrated on detailed information about the development of zirconia for dental use and the mechanical and optical properties, Part II deals with the resulting guidelines for working with the relevant generations by summarizing the correct cementation procedure. Furthermore, this part also focuses on translucency measurements for better characterization and understanding of the different materials. The results obtained from measuring light transmission and contrast ratio are compared and discussed in detail, with the aid of clinical photographs. Finally, the reader is given practice-relevant recommendations for different areas of clinical use of the zirconia generations along with advice on how to process them appropriately.

Polyetheretherketone (PEEK) can be used as a framework material for fixed dental prostheses. However, information about the durable bond to veneering resins is still scarce.The purpose of this study was to investigate the effect of chemical treatments of PEEK on tensile bond strength (TBS) to veneering resins with special emphasis on surface free energy (SFE) and surface roughness (SR).Seven-hundred fifty PEEK specimens were fabricated and divided into the following 3 pretreatment groups (n=250/group): etching with sulfuric acid for 60 seconds, etching with piranha acid for 30 seconds, and an unetched control. After pretreatment, SFE was determined by using contact angle measurements and SR with a profilometer (n=10/group). The topography of pretreated PEEK surfaces was examined with scanning electron microscopy. Remaining specimens (n=240 per group) were conditioned with visio.link or Signum PEEK Bond, or were left untreated as the control group. Half of each group was veneered with Sinfony or VITA VM LC (n=40/group), and TBS was measured after storage in distilled water at 37°C for either 24 hours or 60 days. Data were analyzed by 4-way and 1-way ANOVA followed by the Scheffé post hoc test and chi-square test (α=.05).PEEK specimens etched with sulfuric acid resulted in higher SFE and SR than specimens without pretreatment or etching with piranha acid. Etching with sulfuric acid or piranha acid led to no general recommendations with respect to TBS. Conditioning with visio.link or Signum PEEK Bond significantly increased the TBS (P.001). PEEK veneered with Sinfony showed significantly higher TBS values than those veneered with VITA VM LC (P.001).Sufficient TBS for bonding to veneering resin can only be achieved when additional adhesive materials were applied.

Objective This study investigated the impact of sulfuric acid etching duration of PEEK on work of adhesion (WA) with resin composite cements, and compared additionally measured surface parameters to shear bond strength (SBS) results. Methods PEEK specimens were fabricated and divided according to different etching times using 98% sulfuric acid (N=448/n=54): 0, 5, 15, 30, 60, 90, 120 or 300 s, respectively. The resin composite cements RelyX ARC, Variolink II and Clearfil SA Cement (N=54/n=18) were smoothed on a glass plate. The sessile drop method was applied in all contact-angle measurements; distilled water and diiodomethane served as testing liquids. Overall 1350 single contact angle measurements were performed. Thereafter, surface free energy (SFE), WA, interfacial tension (IFT) and spreading coefficient (SC) of all combinations between etched PEEK and resin composite cements were calculated. Data were statistically analysed using Kolmogorov–Smirnov, Shapiro–Wilk tests, descriptive statistics and two-/one-way ANOVA with post-hoc Scheffe test (p Results Variolink II showed the lowest WA, followed by RelyX ARC and Clearfil SA Cement, respectively. Etching specimens for 60 s showed the lowest WA values while etching times between 0 s and 30 s, and 300 s showed higher results. WA values for groups etched for 90 s and 120 s showed no differences when compared to the 60 s groups. SFE and disperse percentage showed a positive correlation with SBS. A negative correlation was observed between SBS and polar percentage for etched PEEK, WA, IFT and SC. Conclusions The WA values do not allow statements about the bond between two materials to be made; other parameters must be taken into account. A waiver of conventional bond test methods is not possible.

To analyse the marginal fit of 4-unit fixed dental prostheses (FDPs) and the accuracy of three-dimensional cast-datasets using both approaches to Computer Aided Design (CAD)/Computer Aided Manufacturing (CAM): direct and indirect digitalization.A titanium model of a 4-unit FDP was digitized by an intraoral scanning device (iTero, Align Technology, Carlstadt, US; DD, n=12). Additionally 12 conventional impressions were taken and referring master casts were digitized by a laboratory scanner (CS2, Straumann, Basel, Switzerland; ID, n=12). Frameworks were fabricated (CARES CADCAM GmbH, Straumann, Markkleeberg, Germany) from base metal alloy (coron, Straumann; DD-C: n=12; ID-C: n=12) and zirconia (zerion, Straumann; DD-Z: n=12; ID-Z: n=12) from the same datasets. The marginal fit of the resulting frameworks and the accuracy of the underlying datasets from DD and ID were evaluated. Data were analyzed by unpaired two sample Student's t-test with Levene-test (p0.05).Frameworks from group DD-C showed significantly better marginal fit than ID-C (DD-C: 56.90±27.37 μm, ID-C: 90.64±90.81 μm). For zirconia frameworks no differences between both digitalization methods (DD-Z: 127.23±66.87 μm, ID-Z: 141.08±193.17 μm) could be observed. Base metal alloy frameworks exhibited significantly better marginal fit than zirconia frameworks (DD: p0.001; ID: p=0.022). Regarding the accuracy group DD showed significantly higher "trueness" than ID.Direct and indirect digitalization lead to clinically acceptable marginal fit of 4-unit FDPs from base metal alloy and zirconia. Higher accuracy of datasets from DD leads to better marginal fit of frameworks from base metal alloy but not for ones from zirconia.

Objectives To test the tensile bond strength of luted composite computer aided design/computer aided manufacturing (CAD/CAM) crowns after use of different adhesive systems combined with different resin composite cements on dentin abutments. Methods Human molars ( n = 200) were embedded in acrylic resin, prepared in a standardized manner and divided into 20 groups ( n = 10). The crowns were treated as follows: (i) Monobond Plus/Heliobond (MH), (ii) Ambarino P60 (AM), (iii) Visio.link (VL), (iv) VP connect (VP), and (v) non-treated as control groups (CG) and luted with Variolink II (VAR) or Clearfil SA Cement (CSA). Tensile bond strength (TBS) was measured initially (24 h water, 37 °C) and after aging (5000 thermal cycles, 5/55 °C). The failure types were evaluated after debonding. TBS values were analyzed using three-way and one-way ANOVA, followed by post hoc Scheffe-test, and two-sample Student's t -tests. Results Among VAR and after aging, CG presented significantly higher TBS ( p = 0.007) than groups treated with MH, AM and VP. Other groups showed no impact of pre-treatment. A decrease of TBS values after thermal aging was observed within CSA: CG ( p = 0.002), MH ( p p p = 0.002), VP ( p p = 0.002) and AM ( p = 0.014). Groups cemented with VAR showed significantly higher TBS then groups cemented with CSA: non-aged groups: CG ( p p = 0.003), MH ( p p = 0.005), VP ( p = 0.010). Significance According to the study results nano-composite CAD/CAM crowns should be cemented with VAR. Pre-treatment is not necessary if the tested resin composite cements are used.

This study investigated the influence of several dentin bonding agents, resin composites and curing modes on push-out bond strength to human dentin. 360 extracted caries-free third molars were prepared, cut into slices, embedded in epoxy resin and perforated centrally. One half of the specimens (180) were treated by using one-step adhesive systems and the other half (180) with multi-step adhesive systems. Subsequently, the cavities were filled with either universal, flowable or bulk-fill resin composite according to the manufactures&rsquo, product line and cured with either turbo or soft start program. After storage the push-out test was performed. The data was analyzed using Kolmogorov-Smirnov, three- and one-way ANOVA followed by the Scheff&eacute, post-hoc test, unpaired two-sample t-test (p &lt, 0.05). The strongest influence on push-out bond strength was exerted by the resin composite type (partial eta squared &eta, P2 = 0.505, p &lt, 0.001), followed by the adhesive system (&eta, P2 = 0.138, p &lt, 0.001), while the choice of the curing intensity was not significant (p = 0.465). The effect of the binary or ternary combinations of the three parameters was significant for the combinations resin composite type coupled adhesive system (&eta, P2 = 0.054, p &lt, 0.001), only. The flowable resin composites showed predominantly mixed, while the universal and bulk-fill resin composite showed adhesive failure types. Cohesive failure types were not observed in any group. Multi-step adhesive systems are preferable to one-step adhesive systems due to their higher bond strength to dentin. Flowable resin composites showed the highest bond strength and should become more important as restoration material especially in cavity lining. The use of a soft start modus for polymerization of resin composites does not enhance the bond strength to dentin.

Purpose This study analyzed the impact of cement layer thickness (CLT) and Young's modulus of the cement on the stress distribution in a three-unit zirconia fixed dental prosthesis (FDP) and in the bonding interfaces by means of finite element method. Materials and Methods A 3D finite element model was created from a stylized three-unit FDP-cement-tooth/socket system. The pulp and the periodontal ligament were not modeled. Two CLTs (50 and 150 μm) and two values of Young's modulus of the cement (4.9 for simulation of resin cement, 20.1 GPa for glass ionomer cement) were evaluated. A 500 N static vertical load was applied at the central fossa of the pontic to calculate maximum displacement in the framework and maximum principal stresses in both framework and bonding interfaces. Results The simulated results showed that the Young's modulus affected stress occurrence only in the cement interface. Lower moduli were associated with less stress. The thickness of the cement layer influenced the maximum principal stress in both the FDP and in the cement layer itself. Thicker cement layers led to higher stresses in the framework but lower stresses in the cement layer. Maximum displacement was less dependent of the investigated variables. During all trials, the location of the maximum principal stress did not change. Maximum stress concentrations were observed at the lower embrasures of the connector areas and in the bonding layer at the cervical margin of the preparation. Conclusions Choosing cements with a preferably low Young's modulus in combination with a CLT as small as possible might increase the clinical survival rate.

Objectives The authors investigated the use of ceramic primers combined with self-adhesive resin composite cements on the shear bond strength (SBS) to zirconia and compared them with one conventional resin composite cement. Methods The authors divided zirconia substrates (N = 550) into three groups: RelyX Unicem Aplicap self-adhesive universal resin composite cement (3M ESPE, St. Paul, Minn.) (group A) (n = 220); G-CEM Capsule self-adhesive resin composite cement (GC Europe, Leuven, Belgium) (group B) (n = 220); and Panavia 21 with Clearfil Porcelain Bond Activator and Clearfil SE Bond primer (n = 110) (Kuraray Dental, Tokyo) used as a standard comparison (SC). The authors examined the self-adhesive resin composite cements without (0) and with (1) the use of a ceramic primer. They measured SBS initially (37°C for three hours), after water storage (37°C for one, four, nine, 16 or 25 days) and after thermal cycling (5°C and 55°C for 1,500, 6,000, 13,500, 24,000 or 37,500 cycles). The authors analyzed data by using descriptive statistics, the Mann-Whitney test, the Kruskal-Wallis test and a χ 2 test. Results Application of a ceramic primer did not result in a negative impact on SBS. Specimens in the A1 group (that is, RelyX Unicem Aplicap with ceramic primer) exhibited significantly higher SBS before and after water storage and thermal cycling compared with specimens that were not treated with a primer. The self-adhesive resin composite cements combined with ceramic primer exhibited similar or higher SBS values compared with those in the SC group at each aging duration (that is, water storage and thermal cycling). With respect to G-CEM Capsule, the authors observed a significantly positive effect of the primer after nine and 16 days' water storage and after one and four days' thermal cycling. They observed predominantly adhesive failures. Conclusions Ceramic primer in combination with self-adhesive resin composite cement demonstrated a positive effect on SBS to zirconia and should be used for cementation. Practical Implications Long-term adhesion to ceramic plays an important role in the longevity of dental restorations. Therefore, the authors recommend that clinicians use a ceramic primer when cementing zirconia restorations.

Objectives This study evaluated and compared the impact of soldering on fracture resistance of veneered 4-unit fixed dental prostheses (FDPs). Materials and methods Forty-eight 4-unit zirconia frameworks were milled and randomly divided in four groups ( n =12). Untreated frameworks served as control, one group underwent thermal treatment, one group was sectioned and soldered in the connector between both pontics and one group was sectioned and soldered centrally in the mesial pontic. All frameworks were veneered with glass-ceramic material in powder build-up technique. The fracture load was determined on two different failure types, namely on chipping of the veneering ceramic and on total fracture of the FDP. Data were analysed using descriptive statistics, one-way ANOVA together with the Scheffe post-hoc test and Weibull statistics ( p Results The mean range of fracture load of chipped FDPs was determined between 655 N and 789 N; no differences between the tested groups were found ( p =0.587). The mean fracture load until total fracture ranged in all tested groups from 768 N to 1261 N. Sound FDPs and soldered FDPs in the connector area presented lower mean total fracture load compared to soldered FDPs in the pontic ( p Conclusions Soldered zirconia frameworks showed similar in-vitro performance compared to sound frameworks.

OBJECTIVES: To study the surface properties of polyetheretherketone (PEEK) and its bond strength with two veneering resins after different conditioning methods as well as fracture load of PEEK three-unit fixed dental prostheses (FDPs). METHODS: Two hundred and twenty five PEEK specimens were fabricated and divided into five groups: no treatment (A), etching with 98% sulfuric acid for 1 min (B), air-abrasion for 10 s with either 50 or 110 μm alumina (C and D, respectively), and silica coating using the Rocatec System (E). On 15 specimens of each conditioning method, contact angle and surface roughness were determined. The remaining 150 specimens of each conditioning method were divided into two groups for the veneering procedure with the composites Gradia (GC Europe) and Sinfony (3M ESPE). Shear bond strength (SBS) was measured and failure types were assessed. In addition, 15 FDPs were milled and the fracture load was tested. Data were analyzed using descriptive statistics, one-way ANOVA (Scheffe test), two sample Student's t-test, and Weibull statistics (p < 0.05). RESULTS: Silica-coated PEEK surfaces showed the highest wettability. The highest roughness and lowest contact angles were observed for 110 μm air-abraded and silica-coated PEEK surfaces. The highest SBS values were, however, achieved in the acid-etched group. PEEK three-unit FDPs showed a mean fracture load of 1383 N with a plastic deformation starting approximately at 1200 N. CONCLUSIONS: Acid etching should be applied when PEEK is used as substructure material and composite veneering material is applied. In this combination, PEEK might be a suitable material for FDPs, especially in load-bearing areas.

Objectives This study determined the two-body wear and toothbrushing wear parameters, including gloss and roughness measurements and additionally Martens hardness, of nine aesthetic CAD/CAM materials, one direct resin-based nanocomposite plus that of human enamel as a control group. Materials and methods Two-body wear was investigated in a computer-controlled chewing simulator (1.2 million loadings, 49 N at 1.7 Hz; 3000 thermocycles 5/50 °C). Each of the 11 groups consisted of 12 specimens and 12 enamel antagonists. Quantitative analysis of wear was carried out with a 3D-surface analyser. Gloss and roughness measurements were evaluated using a glossmeter and an inductive surface profilometer before and after abrasive toothbrushing of machine-polished specimens. Additionally Martens hardness was measured. Statistically significant differences were calculated with one-way ANOVA (analysis of variance). Results Statistically significant differences were found for two-body wear, gloss, surface roughness and hardness. Zirconium dioxide ceramics showed no material wear and low wear of the enamel antagonist. Two-body wear of CAD/CAM-silicate and -lithium disilicate ceramics, -hybrid ceramics and -nanocomposite as well as direct nanocomposite did not differ significantly from that of human enamel. Temporary polymers showed significantly higher material wear than permanent materials. Abrasive toothbrushing significantly reduced gloss and increased roughness of all materials except zirconium dioxide ceramics. Gloss retention was highest with zirconium dioxide ceramics, silicate ceramics, hybrid ceramics and nanocomposites. Temporary polymers showed least gloss retention. Martens hardness differed significantly among ceramics, between ceramics and composites, and between resin composites and acrylic block materials as well. Conclusions All permanent aesthetic CAD/CAM block materials tested behave similarly or better with respect to two-body wear and toothbrushing wear than human enamel, which is not true for temporary polymer CAD/CAM block materials. Ceramics show the best gloss retention compared to hybrid ceramics, composites and acrylic polymers.

The aim of this study is to evaluate the adhesion between PEEK and two self-adhesive resin cements after plasma treatment.Eight hundred sixty-four polyetheretherketone (PEEK) disks were cut and polished to silicon carbide (SIC) P4000. One half of the specimens were randomly selected and pretreated with plasma, whereas the remaining 432 specimens remained untreated. Subsequently, specimens were randomly allocated to four groups (n = 108/group): Visio.link (Bredent), Signum PEEK Bond (Heraeus Kulzer), Ambarino P60 (Creamed), and a control group without additional treatment. Half of the specimens of each group (n = 54) were then cemented with either RelyX Unicem Automix 2 (3 M ESPE) or with Clearfil SA (Kuraray). All specimens were stored in water for 24 h (37 °C). Afterwards, specimens were divided into three groups (n = 18) for different aging levels: (1) no aging (baseline measurement), (2) thermal aging for 5,000 cycles (5/55 °C), and (3) thermal aging for 10,000 cycles (5/55 °C). Thereafter, shear bond strengths (SBS) were measured, and failure types (adhesive, mixed, and cohesive) were assessed. Data were analyzed using descriptive statistics, four- and one-way ANOVA followed by a post hoc Scheffé test (p 0.05).No adhesion could be established without adhesive pretreatment, irrespectively, whether plasma was applied or not. Also, no bond strength was measured when Ambarino P60 was applied. In contrast, adhesive pretreatment resulted in SBS ranging between 8 and 15 MPa. No significant differences were found between the resin cements used. In general, no cohesive failures were observed. Groups without plasma treatment combined with Visio.link or Signum PEEK Bond showed predominantly mixed failure types. Control groups, plasma treated, or treated using Ambarino P60 groups fractured predominantly adhesively.The use of methyl methacrylate (MMA)-based adhesives allows bonding between PEEK and self-adhesive resin cements. Plasma treatment has no impact on bond to resin cements.PEEK reconstructions can be cemented using self-adhesive resin cements combined with pretreatment with MMA-based adhesives.

Statement of problem Information about the accuracy of digital computer-aided design and computer-aided manufacturing (CAD-CAM) complete dentures is scarce. Purpose The purpose of this in vitro study was to assess the reproducibility of the occlusion of wax dentures fabricated with digital steps and the contraction behavior of wax trial dentures processed with combined conventional-digital steps. These were compared with those fabricated completely conventionally in terms of storage duration. Material and methods Five sets of maxillary and mandibular wax trial dentures were milled from a gingiva-colored wax blank (Ceramill D-Wax, Amann Girrbach AG) using the Ceramill Motion 2 System (Amann Girrbach), scanned, and matched by best-fit triangulation for each of the 5 denture pairs. Processing deformation was measured and the maximum deviations calculated. A 3-dimensional color-coded mapping of the differences between each pair of dentures was generated. Five sets of maxillary and mandibular wax trial dentures were processed with digital steps, and 5 sets of maxillary and mandibular wax trial dentures were fabricated in the conventional way with the help of a silicone index from a CAM-fabricated wax trial denture to standardize the wax amount. All dentures were scanned immediately after waxing and after 1 week of storage. After surface matching, the deformation was measured, and the milled wax bases were compared with those conventionally fabricated. Data were interpreted using descriptive statistics. Results The occlusion of wax trial dentures fabricated with digital steps was not reproducible. The deviations in the maxillary dentures were mostly marginal, with exceptions for single teeth/tooth groups in denture No. 2 (occlusal areas of teeth in second quadrant, second molars) and No. 4 (central incisor and canine in second quadrant inclined to palatal side, and first premolar in first quadrant and first molar in second quadrant displayed greater deviations). Among the mandibular dentures, denture Nos. 4 and 5 the central incisor (fourth quadrant) inclined to the labial side. Additionally, in denture No. 5 the lateral incisor (fourth quadrant) inclined to the lingual side. Conclusions In digitally fabricated dentures, the manual placing of the teeth into the denture base sockets can lead to deviations from the planned arrangement. The deviations were greater in the area of the denture bases in the conventionally fabricated dentures compared with those processed with combined conventional-digital steps. The milled wax bases showed better contraction behavior than the conventionally fabricated wax bases.

STATEMENT OF PROBLEM Polyetheretherketone (PEEK) can be used as a framework material for fixed dental prostheses. However, information about laboratory and chairside polishing methods is still scarce. PURPOSE The purpose of this in vitro study was to determine the effects of laboratory and chairside polishing methods on the surface roughness (SR) and surface free energy (SFE) of PEEK, an autopolymerizing poly(methyl methacrylate), and a veneering composite resin. MATERIAL AND METHODS For each of the 3 materials, 80 specimens were prepared (N=240) and divided into 7 polishing groups and 1 control group (n=10). The 7 groups were split into 4 laboratory protocols: polishing paste (Abraso), a second polishing paste (Opal L), silicone polisher (Ceragum), and diamond grinder (Diagen-Turbo grinder). The other 3 groups were chairside protocols: rainbow technique (Super-Snap kit), polishing paste (Prisma gloss), and a polishing system (Enhance finishing). Machine polishing with SiC P4000 served as the control treatment. The protocols' average SRs and SFEs were measured, and their surface topographies were evaluated with scanning electron microscopy (SEM). The logarithmically transformed data were analyzed using covariance analysis, 2-way and 1-way ANOVA, and partial correlation (α=.05). RESULTS The polishing protocol exerted the highest influence on SR and SFE values (P

Objectives To assess the impact of irradiation on Martens hardness parameters of different PEEK qualities filled with titanium dioxide (TiO 2 ), namely PEEK/0%, PEEK/20%, and PEEK/>30%. Methods For Martens hardness (HM) measurements, 40 specimens of each PEEK quality were fabricated and air-abraded with 50 μm Al 2 O 3 . HM parameters of PEEK specimens were measured initially and stepwise after irradiating for 5, 10, 20, 30, 40, 60, 80, 100, 180, 360 and 540 s using light units with different wavelength: Elipar S10 (430–480 nm), EyeVolutionMAX (385–390 nm + 465–470 nm), Translux CL (380–500 nm) and bre.Lux Power Unit (370–500 nm). HM parameters of 10 human teeth were measured initially on enamel and dentin. Data was analysed using 3-way ANOVA with partial eta-squared ( η P 2 ) and post-hoc Tuckey-HSD-test (p Results PEEK qualities followed by the wavelength showed the highest effect on Martens hardness (p 30% (197.35 ± 19.9 N/mm 2 ), followed by PEEK/20% (191.45 ± 15.49 N/mm 2 ) showed significantly higher values for HM than PEEK/0% (189.55 ± 16.89 N/mm 2 ). PEEK/>30% (5.49 ± 0.4 kN/mm) and PEEK/20% (5.38 ± 0.26 kN/mm 2 ) presented higher indentation modulus (E IT ) than PEEK/0% (4.77 ± 0.36 kN/mm 2 ). Irradiated with wavelength of 430–480 nm (PEEK/0%: 193.28 N/mm 2 , PEEK20%: 198.83 N/mm 2 , PEEK/>30%: 200.5 N/mm 2 ) indicated higher HM compared to specimens irradiated with 380–500 nm (PEEK/0%: 186.63 N/mm 2 , PEEK20%: 191.05 N/mm 2 , PEEK/>30%: 196.13 N/mm 2 ). Irradiation using 430–480 nm (PEEK/0%: 4.95 kN/mm 2 , PEEK20%: 5.52 kN/mm 2 , PEEK/>30%: 5.59 kN/mm 2 ) and 370–500 nm (PEEK/0%: 4.92 kN/mm 2 , PEEK20%: 5.43 kN/mm 2 , PEEK/>30%: 5.53 kN/mm 2 ) indicated higher E IT values compared to specimens irradiated with 380–500 nm (PEEK/0%: 4.72 kN/mm 2 , PEEK20%: 5.34 kN/mm 2 , PEEK/>30%: 5.47 kN/mm 2 ). Duration of irradiation presented no impact on results. Enamel (HM: 2263.6 ± 405.16, E IT : 63.16 ± 19.24) and dentin (HM: 468.2 ± 30.77 N/mm 2 , E IT : 14.14 ± 4.59 kN/mm 2 ) presented significantly higher HM and E IT than the tested PEEK qualities (p Significance Irradiation with different wavelength impacted HM parameter. The increase of TiO 2 percentage in PEEK matrix improved the HM parameter. However, PEEK showed significantly lower HM parameter than human teeth.

This study investigated the impact of different light curing units (LCUs) for the polymerization of adhesive system visio.link (VL) on the tensile bond strength (TBS) of different PEEK compositions. For TBS measurements, 216 PEEK specimens with varying amounts of TiO2 (PEEK/0%, PEEK/20%, PEEK/>30%) were embedded, polished, air abraded (Al2O3, 50 µm, 0.4 MPa), conditioned using VL, and polymerized using either a halogen LCU (HAL-LCU) or a LED LCU (LED-LCU) for chairside or labside application, respectively. After thermocycling (5000×, 5/55 °C), TBS was measured, and fracture types were determined. Data was analyzed using a 2-way ANOVA followed by Tukey–HSD, Kruskal–Wallis H and Mann–Whitney U tests as well as a Chi2-test and a Ciba–Geigy table (p < 0.05). Globally, the light curing units, followed by PEEK composition, was shown to have the highest impact on TBS. The HAL-LCUs, compared to the LED-LCUs, resulted in a higher TBS for all PEEK compositions—without significant differences between chairside and labside units. Regarding the different PEEK compositions, PEEK/20%, compared to PEEK/0%, resulted in a higher TBS when both, HAL-LCUs or LED-LCUs were used for labside application. In comparison with PEEK/>30%, PEEK/20% resulted in a higher TBS after using HAL-LCU for labside application. No significant differences were found between PEEK/0% and PEEK/>30%. HAL-LCU with PEEK/20% for labside application showed a higher TBS than HAL-LCU with PEEK/20% for chairside application, whereas LED-LCU with PEEK/>30% for chairside application showed a higher TBS than LED-LCU with PEEK/>30% for labside application.

SUMMARY 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

This study evaluated the fracture loads of different threeunit fixed dental prostheses (FDPs) for temporary restorations. In total, three CAD/CAM materials (VITA CADTemp [CT], Telio CAD [TC], and ZENO ProFix [ZP]) and two chairside materials (Protemp 4 [PT], and Dentalon Plus [DP]) were used for the fabrication of the FDPs. Sixteen FDPs were fabricated from each material in an anatomical shape and stored in 0.9% NaCl solution at 37°C for 14 days. Thereafter, one half of the specimens from each group (n = 8) were additionally mechanically and thermally loaded (240,000 chewing cycles, 50 N, 5°/55°C, 2,100 thermal cycles). Fracture loads were measured and data analyzed using two- and one-way ANOVA, followed by Scheffé's post hoc test. ZP showed the highest mean fracture loads, regardless of the aging regime. Significantly lowest values were identified for DP and TC within the non-thermal loaded group, and for PT and CT within the thermal loaded group. No negative impact of aging regimes could be observed.

Zirconia as a restoration dental material are gaining attention because of their high mechanical properties and good biocompatibility. Therefore, investigation of the flexural strength of zirconia is of great interest. For this purpose, Weibull statistics for description of the material reliability are frequently used. The aim of this work was to present a blinded data set to two independent statisticians for two parallel statistical analyses in order to find an optimal statistical approach for analysis of in-vitro measured flexural strength data of zirconia materials. A prospectively planned independent blinded statistical analysis implementing three quality control actions "blinded data set", "independent statistical analyses" and "parallel manuscript writing" was designed. Statistical analysis paths taken by both biostatisticians differed. They arrived at complementary results. The major difference was caused by two alternative distributional assumptions (Weibull/Normal) and alternative fitting methods (LS/ML). The parallel statistical analysis and manuscript writing approach on a blinded data set greatly supported our choice of statistical methods for analysis of flexural strength results of zirconia materials.

This study investigated the colorimetric properties of different veneering materials on core materials. Standardized specimens (10 mm × 10 mm × 1.5 mm) reflecting four core (polyetheretherketone (PEEK), zirconia (ZrO2), cobalt–chromium–molybdenum alloy (CoCrMo), and titanium oxide (TiO2); thickness: 1.5 mm) and veneering materials (VITA Mark II, IPS e.max CAD, LAVA Ultimate and VITA Enamic, all in shade A3; thickness: 0.5, 1.0, 1.5 and 2 mm, respectively) were fabricated. Specimens were superimposed to assemblies, and the color was determined with a spectrophotometer (CieLab-System) or a chair-side color measurement device (VITA EasyShade), respectively. Data were analyzed using three-, two-, and one-way ANOVA, a Chi2-test, and a Wilson approach (p < 0.05). The measurements with EasyShade showed A2 for VITA Mark II, A3.5 for VITA Enamic, B2 for LAVA Ultimate, and B3 for IPS e.max CAD. LabE-values showed significant differences between the tested veneering materials (p < 0.001). CieLab-System and VITA EasyShade parameters of the different assemblies showed a significant impact of core (p < 0.001), veneering material (p < 0.001), and thickness of the veneering material (p < 0.001). PEEK as core material showed comparable outcomes as compared to ZrO2 and CoCrMo, with respect to CieLab-System parameters for each veneering material. The relative frequency of the measured VITA EasyShade parameters regarding PEEK cores also showed comparable results as compared to the gold standard CoCrMo, regardless of the veneering material used.

Pull-out testing was used to determine the tensile load (TL) and tensile strength (TS) of five different fiber post systems bonded to human intracanal dentin.120 caries-free premolars, canines, and maxillary central incisors were divided into 5 different groups for 5 fiber post systems (n = 24): 1. RelyX Fiber Post 3D (RX3D); 2. RelyX Fiber Post (RX); 3. Luxa- Post (LP); 4. FibreKleer 4X Tapered Post (FK); 5. ParaPost Taper Lux (PP). The teeth were prepared and posts inserted. Core buildups were performed with the corresponding product's resin composite. All specimens were stored in water for 24 h at 37°C. TL and TS were tested on half of the specimens (n = 12/group). The remaining samples were thermocycled (10,000 x 5°C/55°C) before testing. TL was directly measured and TS was calculated using the bonding surface. Failure modes were identified using a stereomicroscope. Data were analyzed using twoway ANOVA with the post-hoc Scheffé test, as well as the chi-squared test (p0.05).FK and LP resulted in the lowest mean TL but were not significantly different from those of RX and RX3D. The highest mean TL and TS were observed for PP. Nevertheless, PP fell within the same statistical subset as RX3D and RX. Thermocycling showed no impact on the results. RX3D predominantly showed debonding of the post plus core buildup from the tooth; all other systems mainly demonstrated detachment of the core from the posts.PP, RX, and RX3D together with an adhesive core buildup yielded the highest bond strength to human dentin. Parameters TL and TS showed the same tendencies and statistical evidence.

In prosthetic dentistry, double crown systems have proved their suitability as retainers for removable partial dentures. However, investigations in this context, regarding polyetheretherketone, are scarce. Therefore, the aim of this study was to test the retention force (RF) between polyetheretherketone (PEEK) primary and cobalt-chromium (CoCr), zirconia (ZrO2) and galvanic (GAL) secondary crowns with three different tapers. Primary PEEK-crowns were milled with the tapers 0°, 1°, and 2° (n = 10/taper, respectively). Afterwards, 90 secondary crowns were fabricated: (i) 30 CoCr-crowns milled from Ceramill Sintron (AmannGirrbach, Koblach, Austria) (n = 10/taper), (ii) 30 ZrO2-crowns milled from Ceramill ZI (AmannGirrbach, Koblach, Austria) (n = 10/taper), and (iii) 30 GAL-crowns made using electroforming (n = 10/taper). RF was measured in a pull-off test (20 pull-offs/specimen) and data were analyzed using 2-/1-way Analysis of Variance (ANOVA) followed by the Tukey-Honestly Significant Difference (HSD) post hoc test and linear regression analyses (p < 0.05). The measured mean RF values ranged between 9.6 and 38.2 N. With regard to the 0°, 1°, and 2° tapered crowns, no statistically significant differences between CoCr and ZrO2 were observed (p > 0.141). At 0° taper, no differences in retention forces between GAL, CrCr, and ZrO2 crowns were found (p = 0.075). However, at 1° and 2° taper, lower RF for GAL-crowns were observed (p < 0.009, p < 0.001, respectively). According to this laboratory study, PEEK might be a suitable material for primary crowns, regardless of the taper and the material of secondary crown. Long-term results, however, are still necessary.

Objectives This study evaluated and compared Weibull parameters of resin bond strength values using six different general-purpose statistical software packages for two-parameter Weibull distribution. Methods Two-hundred human teeth were randomly divided into 4 groups ( n = 50), prepared and bonded on dentin according to the manufacturers’ instructions using the following resin cements: (i) Variolink (VAN, conventional resin cement), (ii) Panavia21 (PAN, conventional resin cement), (iii) RelyX Unicem (RXU, self-adhesive resin cement) and (iv) G-Cem (GCM, self-adhesive resin cement). Subsequently, all specimens were stored in water for 24 h at 37 °C. Shear bond strength was measured and the data were analyzed using Anderson–Darling goodness-of-fit (MINITAB 16) and two-parameter Weibull statistics with the following statistical software packages: Excel 2011, SPSS 19, MINITAB 16, R 2.12.1, SAS 9.1.3. and STATA 11.2 ( p ≤ 0.05). Additionally, the three-parameter Weibull was fitted using MNITAB 16. Results Two-parameter Weibull calculated with MINITAB and STATA can be compared using an omnibus test and using 95% CI. In SAS only 95% CI were directly obtained from the output. R provided no estimates of 95% CI. In both SAS and R the global comparison of the characteristic bond strength among groups is provided by means of the Weibull regression. EXCEL and SPSS provided no default information about 95% CI and no significance test for the comparison of Weibull parameters among the groups. In summary, conventional resin cement VAN showed the highest Weibull modulus and characteristic bond strength. Significance There are discrepancies in the Weibull statistics depending on the software package and the estimation method. The information content in the default output provided by the software packages differs to very high extent.

Objective The study aimed to analyze the shear bond strength of aged silorane composite repaired with the same substrate or a conventional methacrylate-based composite after different mechanical and adhesive surface treatments. Methods Silorane composite specimens were aged by thermal cycling (5000 cycles, 5–55 °C) and randomly assigned to different surface treatments (each group n = 16): diamond bur abrasion, aluminum oxide sandblasting, silica coating, or hydrofluoric acid etching. Then, an adhesive system corresponding to the repair composite or a combination of silane agent and the respective adhesive was applied. Silorane composite or a nanofiller composite were adhered onto the conditioned surfaces. In the control group ( n = 16), silorane composite was adhered to fresh substrate (incremental build up). After further thermal cycling, shear bond strength was tested and failure modes were assessed. Data were analyzed by ANOVA/post hoc tests, Weibull statistics and Chi 2 -test ( p ≤ 0.05). Results Incremental shear bond strength (control group: 21.0 ± 10.5 MPa) was achieved by all groups except those etched with hydrofluoric acid or samples abraded with diamond bur and repaired with the nanofiller composite without silane application. Generally, the application of the silane agent improved repair bond strength of the nanofiller but not of the silorane composite. Cohesive failure was observed more frequently than adhesive failure when the silane agent was applied or when silorane composite was used for repair. Significance Silorane composite can be repaired with either the same substrate or a methacrylate-based nanofiller composite but requires mechanical surface treatment and – in case of the methacrylate-based composite – silanization prior to adhesive application.

Objective: This study investigated the effect of sintering temperatures on flexural strength, contrast ratio, and grain size of zirconia. Materials and Methods: Zirconia specimens (Ceramill ZI, Amann Girrbach) were prepared in partially sintered state. Subsequently, the specimens were randomly divided into nine groups and sintered with different final sintering temperatures: 1,300°C, 1,350°C, 1,400°C, 1,450°C, 1,500°C, 1,550°C, 1,600°C, 1,650°C, or 1,700°C with 120min holding time. Three-point flexural strength (N = 198; n = 22 per group) was measured according to ISO 6872: 2008. The contrast ratio (N = 90; n = 10 per group) was measured according to ISO 2471: 2008. Grain sizes and microstructure of different groups were investigated (N = 9, n = 1 per group) with scanning electron microscope. Data were analyzed using one-way ANOVA with Scheffé test and Weibull statistics (p

Objectives: To test the fracture load of zirconia abutments with different types of implant-abutment connections after chewing simulation and to compare their bending moments to internally connected identical titanium abutments. Materials and methods: Forty-eight identical customized zirconia abutments with different implant-abutment connections were fabricated for four different test groups: one-piece internal implant-abutment connection (BL; Straumann Bonelevel), two-piece internal implant-abutment connection (RS; Nobel Biocare Replace Select), external implant-abutment connection (B; Branemark MK III), two-piece internal implant-abutment connection (SP; Straumann Standard Plus). Twelve titanium abutments with one-piece internal implant-abutment connection (T; Straumann Bonelevel) served as control group. After aging by means of thermocycling (5-50°C, 120 s) and chewing simulation (1,200,000 cycles, 49 N load, 1.67 Hz), static load was applied at a 30° angle to the palatal surface until failure. Bending moments were calculated for comparison of the groups. Data were analyzed descriptively and by performing the Kruskal-Wallis test with Bonferroni correction. Results: The mean bending moments of the abutments were 714.1 ± 184.9 N cm (T), 331.7 ± 57.8 N cm (BL), 429.7 ± 62.8 N cm (RS), 285.8 ± 64.4 N cm (B) and 379.9 ± 59.1 N cm (SP). The bending moments of control group T were significantly higher than those of all other groups. The values of group RS were significantly higher than those of group B but within the value range of groups SP and BL. Conclusion: The bending moments of the different tested types of zirconia abutments vary with different implant-abutment connections after chewing simulation. The use of a secondary metallic component might have a beneficial influence on the stability of zirconia abutments. To cite this article: Truninger TC, Stawarczyk B, Leutert CR, Sailer TR, Hammerle CHF, Sailer I. Bending moments of zirconia and titanium abutments with internal and external implant-abutment connections after aging and chewing simulation. Clin. Oral Impl. Res. 23, 2012; 12-18. doi: 10.1111/j.1600-0501.2010.02141.x.

Objectives The aim of this in vitro study was to assess the influence of thermal properties of veneering ceramics on the fracture load of layered ceria stabilized zirconia/alumina nanocomposite (Ce-TZP/A) single crowns. Methods Ce-TZP/A single crown frameworks (nanoZr) were veneered with 5 different veneering ceramics for zirconia (Cerabien ZR, IPS e.max, Triceram, Vintage ZR, VM9). In addition, veneering ceramics for alumina (Allux) and for the metal–ceramic technique (Reflex) were included in order to cover a wide range of coefficients of thermal expansion. Fracture load of the crowns was assessed in a shear test ( n = 10). Glass transition temperatures ( T g ) of the ceramics as well as the coefficients of thermal expansion of the ceramics ( α veneer ) and Ce-TZP/A ( α core ) between 25 and 500 °C were determined ( n = 6). Results Fracture load ranged from 574.0 ± 97.1 N (IPS e.max) to 1009.6 ± 150.0 N (VM9). Δ α = α core − α veneer and Δ T = T g − 25 °C (Δ T in K) were calculated. The fracture load was strongly correlated to Δ α Δ T with a maximum at Δ α Δ T ≈ 580 × 10 −6 . Significance The overall fracture load of veneered Ce-TZP/A crowns is correlated to the thermal properties of the respective veneering ceramic.

To investigate the retention loads of differently fabricated secondary telescopic polyetheretherketone (PEEK) crowns on cobalt-chromium primary crowns with different tapers.Cobalt-chromium primary crowns with 0°, 1°, and 2° tapers were constructed, milled, and sintered. Corresponding secondary crowns were fabricated by milling, pressing from pellets, and pressing from granules. For these nine test groups, the pull-off tests of each crown combination were performed 20 times, and the retention loads were measured (Zwick 1445, 50 mm/min). Data were analyzed using linear regression, covariance analysis, mixed models, Kruskal-Wallis, and Mann-Whitney U-test, together with the Benferroni-Holm correction.The mixed models covariance analysis reinforced stable retention load values (p = 0.162) for each single test sequence. There was no interaction between the groups and the separation cycles (p = 0.179). Milled secondary crowns with 0° showed the lowest mean retention load values compared to all tested groups (p = 0.003) followed by those pressed form pellets with 1°. Regarding the different tapers, no effect of manufacturing method on the results was observed within 1° and 2° groups (p = 0.540; p = 0.052); however, among the 0° groups, the milled ones showed significantly the lowest retention load values (p = 0.002). Among the manufacturing methods, both pressed groups showed no impact of taper on the retention load values (p0.324 and p0.123, respectively), whereas among the milled secondary crowns, the 0° taper showed significantly lower retention load values than the 1° and 2° taper (p0.002).Based on these results, telescopic crowns made of PEEK seem to show stable retention load values for each test sequence; however, data with thermo-mechanical aging are still required. In addition, further developments in CAD/CAM manufacturing of PEEK materials for telescopic crowns are warranted, especially for 0°.

The aim of this work was to evaluate the influence of specimen preparation and test method on the flexural strength results of monolithic zirconia. Different monolithic zirconia materials (Ceramill Zolid (Amann Girrbach, Koblach, Austria), Zenostar ZrTranslucent (Wieland Dental, Pforzheim, Germany), and DD Bio zx2 (Dental Direkt, Spenge, Germany)) were tested with three different methods: 3-point, 4-point, and biaxial flexural strength. Additionally, different specimen preparation methods were applied: either dry polishing before sintering or wet polishing after sintering. Each subgroup included 40 specimens. The surface roughness was assessed using scanning electron microscopy (SEM) and a profilometer whereas monoclinic phase transformation was investigated with X-ray diffraction. The data were analyzed using a three-way Analysis of Variance (ANOVA) with respect to the three factors: zirconia, specimen preparation, and test method. One-way ANOVA was conducted for the test method and zirconia factors within the combination of two other factors. A 2-parameter Weibull distribution assumption was applied to analyze the reliability under different testing conditions. In general, values measured using the 4-point test method presented the lowest flexural strength values. The flexural strength findings can be grouped in the following order: 4-point < 3-point < biaxial. Specimens prepared after sintering showed significantly higher flexural strength values than prepared before sintering. The Weibull moduli ranged from 5.1 to 16.5. Specimens polished before sintering showed higher surface roughness values than specimens polished after sintering. In contrast, no strong impact of the polishing procedures on the monoclinic surface layer was observed. No impact of zirconia material on flexural strength was found. The test method and the preparation method significantly influenced the flexural strength values.

OBJECTIVES To evaluate marginal adaptation, fracture load and failure types of CAD/CAM polymeric inlays. METHODS Standardized prepared human molars (48) were divided into four groups (n=12): (A) PCG (positive control group); adhesively luted glass-ceramic inlays, (B) TRX; CAD/CAM polymeric inlays luted using a self-adhesive resin cement, (C) TAC; CAD/CAM polymeric inlays luted using a conventional resin cement, and (D) NCG (negative control group); direct-filled resin-based composite restorations. All specimens were subjected to a chewing simulator. Before and after chewing fatigue, marginal adaptation was assessed at two interfaces: (1) between dental hard tissues and luting cement and (2) between luting cement and restoration. Thereafter, the specimens were loaded and the fracture loads, as well as the failure types, were determined. The data were analysed using three- and one-way ANOVA with post hoc Scheffe test, two sample Student's t-test (p

Objective To test and compare the two-body wear rate of three CAD/CAM polymer materials and the influence of specimen geometry, antagonist material and test set-up configuration. Methods Three CAD/CAM polymeric materials were assessed: a thermoplastic polyetheretherketone (PEEK), an experimental nanohybrid composite (COMP) and a PMMA-based material (PMMA). Crown-shaped and flat specimens were prepared from each material. The specimens underwent thermo-mechanical loading (50 N, 5/55 °C; 600,000 chewing cycles) opposed to human enamel and stainless steel antagonists. Half of the specimens of each group were loaded with a sliding movement of 0.7 mm, the remaining half without. Thereby, 24 different test set-ups were investigated ( n = 12). Wear of the materials and antagonists was evaluated with a match-3D procedure. The topography of all surfaces was examined with scanning electron microscopy (SEM). Data were statistically evaluated with four-/one-way ANOVA followed by Scheffe post hoc test and unpaired t -test ( p Results All PEEK specimens showed significantly less material loss than COMP and PMMA specimens when loaded laterally. Within the axial loaded groups this was only true for the flat specimens tested with enamel antagonists. Crown specimens of these groups exhibited lower loss values than flat ones. Lateral force application led mostly to significantly higher material loss than the axial load application. On the antagonist side, no impact of CAD/CAM polymer material, antagonist material, force application and specimen geometry was found. Significance Wear of PEEK was lower than that of the resin-based materials when lateral forces were applied, but showed comparable antagonist wear rates at the same time.

The aim of this study was to assess the bonding properties between CAD/CAM resin and three resin composite cements combined with different bonding agents using three test methods.Four hundred twenty CAD/CAM resin substrates were fabricated and divided into three test methods (shear bond strength (SBS, n = 180), tensile bond strength (TBS, n = 180) and work of adhesion (WA, n = 60)), further into four pretreatment methods (VP connect (VP), visio.link (VL), Clearfil Ceramic Primer (CP) and no pretreatment (CG)) and three cements (RelyX ARC, Variolink II and Clearfil SA Cement). Each subgroup contained 15 specimens. SBS and TBS were measured after 24 h H2O/37 °C + 5000 thermal-cycles (5/55 °C) and failure types were assessed. WA was determined for pretreated CAD/CAM resin and non-polymerized resin composite cements. Data were analysed with Mann-Whitney U, Kruskal-Wallis H, Chi(2) and Spearman's Rho tests.Within SBS and TBS tests, CGs and groups pretreated with CP (regardless of resin composite cements), and VP pretreated with Clearfil SA Cement showed no bond. However, CG combined with RelyX ARC showed a TBS of 5.6 ± 1.3 MPa. In general, highest bond strength was observed for groups treated with VL. CG and groups pretreated using VL showed lower WA than the groups treated with VP or CP.Measured TBS values were higher than SBS ones. In general, SBS and TBS showed similar trends for the ranges of the values for the groups. WA results were not comparable with SBS/TBS results and admitted, therefore, no conclusions on it.For a clinical use of XHIP-CAD/CAM resin, the bond surface should be additionally pretreated with visio.link as bonding agent.

This study aimed to examine and compare the retention load values (RL) of different telescopic crown assemblies (Y-TZP and CoCr primary crowns with electroformed and Y-TZP secondary crowns each) with three different taper angles (0°, 1° and 2°). Thirty Y-TZP primary crowns with electroformed gold copings (Z/G group) and Y-TZP secondary crowns (Z/Z group) and 30 CoCr primary crowns with electroformed gold copings (C/G group) and Y-TZP secondary crowns (C/Z group), each with taper angles of 0°, 1° and 2°, were fabricated, respectively. With the exception of the electroformed gold copings, all specimens were Computer-Aided-Design/Computer-Aided-Manufacturing (CAD/CAM)-milled, then sintered and afterwards manually adapted. In order to stabilize the gold copings, they were fixed in a tertiary structure. The secondary crowns were constructed with a hook, which ensured self-alignment with an upper chain. Afterwards, 20 pull-off test cycles were performed in a universal testing machine under artificial saliva and after weighing the secondary crowns with a 5 kg object for 20 s. Data were analyzed by one-way and two-way Analysis of Variance (ANOVA). C/Z with 1° showed higher (p = 0.009) RL than 0° and 2° tapers. C/G at 1° also showed higher (p = 0.001) RL than at tapers of 0° and 2°. Z/G and C/G at 0° showed lower RL than Z/Z and C/Z (p < 0.001). Primary crowns had no impact on the 0° group. Z/G showed lower RL as compared to C/Z within the 1° group (p = 0.007) and Z/Z in the 2° group (p = 0.006). The primary crown material had no influence on RL. Electroformed copings showed lower RL. Further investigations for 1° as well as for the long-term performance after thermomechanical aging are necessary.

This study investigates the retention load (RL) between ZrO2 primary crowns and secondary polyetheretherketone (PEEK) crowns made by different fabrication methods with three different tapers. Standardized primary ZrO2 crowns were fabricated with three different tapers: 0°, 1°, and 2° (n = 10/group). Ten secondary crowns were fabricated (i) milled from breCam BioHPP blanks (PM); (ii) pressed from industrially fabricated PEEK pellets (PP) (BioHPP Pellet); or (iii) pressed from granular PEEK (PG) (BioHPP Granulat). One calibrated operator adjusted all crowns. In total, the RL of 90 secondary crowns were measured in pull-off tests at 50 mm/min, and each specimen was tested 20 times. Two- and one-way ANOVAs followed by a Scheffé’s post-hoc test were used for data analysis (p < 0.05). Within crowns with a 0° taper, the PP group showed significantly higher retention load values compared with the other groups. Among the 1° taper, the PM group presented significantly lower retention loads than the PP group. However, the pressing type had no impact on the results. Within the 2° taper, the fabrication method had no influence on the RL. Within the PM group, the 2° taper showed significantly higher retention load compared with the 1° taper. The taper with 0° was in the same range value as the 1° and 2° tapers. No impact of the taper on the retention value was observed between the PP groups. Within the PG groups, the 0° taper presented significantly lower RL than the 1° taper, whereas the 2° taper showed no differences. The fabrication method of the secondary PEEK crowns and taper angles showed no consistent effect within all tested groups.

Due to its high fracture toughness ceria-stabilized ZrO(2)/Al(2)O(3) nanocomposite (Ce-TZP/A) could be superior to Y-TZP in clinical use. However, the compatibility to veneering ceramics is not yet investigated and therefore subject of this study.Fracture strength and crazing resistance of veneered Ce-TZP/A frameworks (Nanozir, Matsushita Electric Works) were investigated in comparison to sintered and hipped Y-TZP (Hint-ELs). Frameworks were machined (HiCut, Hint-ELs), sintered where applicable (hiTherm, Hint-ELs), and veneered in a standardized procedure (Cerabien ZR, Noritake). Fracture strength of the crowns was assessed in a shear test (n=10). Biaxial flexural strength of the core materials was measured according to ISO 6872 (n=10). To assess the thermal compatibility between framework and veneer the coefficient of thermal expansion (CTE) of all materials was determined (n=3) and a crazing test carried out (n=12).Fracture strength was equal for crowns with Ce-TZP/A (866.6+/-132.1N) and sintered Y-TZP (904.5+/-168.2N), while crowns with hipped Y-TZP were significantly stronger (1380.6+/-253.2N) (Student's t-test, p0.05). These values correlated with the biaxial flexural strength of the three core materials (Ce-TZP/A: 1238.0+/-200.0MPa, sintered Y-TZP: 1181.8+/-232.5MPa and hipped Y-TZP: 1521.8+/-163.8MPa). Failure of both hipped and sintered Y-TZP crowns occurred by chipping of the veneer or total fracture, while the Ce-TZP/A crowns predominantly failed by chipping of the veneer. In the crazing test both sintered and hipped Y-TZP performed slightly better than Ce-TZP/A. CTE's were as follows: Ce-TZP/A: 10.3microm/mK, sintered Y-TZP: 10.7microm/mK, hipped Y-TZP: 10.9microm/mK, and Cerabien ZR: 9.9microm/mK.The CTE of the veneering ceramic has to be adjusted to Ce-TZP/A frameworks.

To test the impact of preheating (25, 37, 54, or 68 °C) of TetricEvoCeram (TEC), FiltekSupremeXT (FSXT), and Venus (V) on flexural strength (FS), shear bond strength (SBS) and interfacial tension (IFT). FS was tested with TEC and FSXT. For SBS, glass-ceramic and human dentin substrate were fabricated and luted with the preheated resin composite (RC). SBSs of 1500 thermal cycled specimens were measured. For IFT, glass slides covered with the non-polymerized RC were prepared and contact angles were measured. Data were analyzed using 2/1-way ANOVA with Scheffé-test, and t-test (p < 0.05). Preheated TEC (37–68 °C) showed higher FS compared to the control-group (25 °C) (p < 0.001). FSXT presented higher FS than TEC (p < 0.001). For SBS to dentin higher values for FSXT than TEC were found. The preheating temperature showed no impact on SBS to dentin. SBS to glass-ceramic revealed a positive influence of temperature for TEC 25–68 °C (p = 0.015). TEC showed higher values than V and FSXT (p < 0.001). IFT values increased with the preheating temperature. A significant difference could be observed in every RC group between 25 and 68 °C (p < 0.001).

The aim of this study is to investigate the fracture load of different veneered PEEK 3-unit fixed dental prosthesis (FDPs) after different aging regimens. Congruently anatomically shaped 3-unit FDPs were milled using a master stl-data set and randomly divided into four groups (N = 120, n = 30 per veneering group), which were veneered using different veneering methods: (i) digital veneering with breCAM.HIPC, (ii) conventional veneering with crea.lign, (iii) conventional with crea.lign paste, and (iv) using pre-manufactured veneers visio.lign. The FDPs were then adhesively cemented on a metal abutment and fracture loads were measured in a universal testing machine (1 mm/min) before and after aging (10,000 thermal cycles, 5/55 °C). Two- and one-way ANOVA followed by post hoc Scheffe tests were used for data analysis (p