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Statement of problem Polyphenylene sulfone (PPSU) is a thermoplastic that can be processed using 3-dimensional printing. PPSU is new to dentistry, and scientific data on its properties are lacking. Purpose The purpose of this in vitro study was to test the surface properties and the tensile bond strength (TBS) between PPSU and a veneering composite resin in comparison with a polyetheretherketone (PEEK). Material and methods Gehr PPSU (PPSU-B1), Radel R-5000 NT (PPSU-B2), and Juvora Dental Disc (PEEK-CG) substrates were cut from bulk material, while FIL-A-GEHR PPSU (PPSU-3D) was 3-dimensionally printed (N=504, n=126/material). TBS to veneering composite resin (CeramageUp) was tested initially and after 5000 and 10 000 thermocycles, and fracture types were analyzed. Surface free energy (SFE) and surface roughness (Ra) were determined after pretreatment with aluminum oxide (Al2O3) of different grain sizes (50 and 110 μm) applied with different pressures (0.1, 0.2, 0.4 MPa), silicon dioxide (SiO2)-coated Al2O3 (0.28 MPa), sulfuric acid, or polished. Qualitative surface characterization was performed by using a scanning electron microscope (SEM). One-way ANOVA, the Kruskal-Wallis, Mann-Whitney U, and the Spearman correlation tests were computed (α=.05). Results PPSU-3D and PEEK-CG presented higher TBS results than PPSU-B1 and PPSU-B2. Initial TBS values were higher than after 10 000 thermocycles. Adhesive fractures between substrate and veneering composite resin occurred most frequently. With a few exceptions, PEEK-CG presented higher SFE values than all other materials within a pretreatment group, while PPSU-3D and PEEK-CG showed consistently high Ra values. An increase in pressure and particle size increased SFE and Ra. Conclusions FFF-printed PPSU-3D showed similar TBS values with the veneering composite resin to the more established PEEK. Pretreatment methods devised for PEEK represent valid strategies for increasing both the SFE and Ra of the high-performance polymer PPSU.

Objectives To investigate the chemical (degree of conversion (DC)) and mechanical properties (Martens hardness (HM), elastic indentation modulus (EIT), and biaxial flexural strength (BFS)) of four dual-polymerizing resin composite core build-up materials after light- and self-polymerization. Materials and methods Round specimens with a diameter of 12 mm and a thickness of 1.5 mm were manufactured from CLEARFIL DC CORE PLUS (CLE; Kuraray), core·X flow (COR; Dentsply Sirona), MultiCore Flow (MUL; Ivoclar Vivadent), and Rebilda DC (REB; VOCO) (N = 96, n = 24/material). Half of the specimens were light-polymerized (Elipar DeepCure-S, 3 M), while the other half cured by self-polymerization (n = 12/group). Immediately after fabrication, the DC, HM, EIT, and BFS were determined. Data was analyzed using Kolmogorov–Smirnov, Mann–Whitney U, and Kruskal–Wallis tests, Spearman’s correlation, and Weibull statistics (p Results Light-polymerization either led to similar EIT (MUL; p = 0.119) and BFS (MUL and REB; p = 0.094–0.326) values or higher DC, HM, EIT, and BFS results (all other groups; p p p p = 0.020) and Weibull modulus after light-polymerization. Positive correlations between all four tested parameters (R = 0.527–0.963, p Conclusions For the tested resin composite core build-up materials, light-polymerization led to similar or superior values for the degree of conversion, Martens hardness, elastic indentation modulus, and biaxial flexural strength than observed after self-polymerization. Among the tested materials, COR should represent the resin composite core build-up material of choice due to its high chemical (degree of conversion) and mechanical (Martens hardness, elastic indentation modulus, and biaxial flexural strength) properties and its high reliability after light-polymerization. The examined chemical and mechanical properties showed a positive correlation. Clinical relevance The chemical and mechanical performance of dual-polymerizing resin composite core build-up materials is significantly affected by the chosen polymerization mode.

Objective The study aims to investigate the shear bond strength (SBS) between silicate ceramic restorations and ceramic brackets after different pretreatments and aging methods. Material and methods Leucite (LEU) and lithium disilicate (LiSi) specimens were pretreated with (i) 4% hydrofluoric acid + silane (HF), (ii) Monobond Etch&Prime (MEP), (iii) silicatization + silane (CoJet), and (iv) SiC grinder + silane (SiC). Molars etched (phosphoric acid) and conditioned acted as comparison group. SBS was measured after 24 h (distilled water, 37 °C), 500 × thermocycling (5/55 °C), and 90 days (distilled water, 37 °C). Data was analyzed using Shapiro–Wilk, Kruskal–Wallis with Dunn’s post hoc test and Bonferroni correction, Mann–Whitney U, and Chi2 test (p Results LEU pretreated with MEP showed lower SBS than pretreated with HF, CoJet, or SiC. LiSi pretreated with MEP resulted in lower initial SBS than pretreated with HF or SiC. After thermocycling, pretreatment using MEP led to lower SBS than with CoJet. Within LiSi group, after 90 days, the pretreatment using SiC resulted in lowest SBS values. After HF and MEP pretreatment, LEU showed lower initial SBS than LiSi. After 90 days of water storage, within specimens pretreated using CoJet or SiC showed LEU higher SBS than LiSi. Enamel presented higher or comparable SBS values to LEU and LiSi. With exception of MEP pretreatment, ARI 3 was predominantly observed, regardless the substrate, pretreatment, and aging level. Conclusions MEP pretreatment presented the lowest SBS values, regardless the silicate ceramic and aging level. Further research is necessary. Clinical relevance There is no need for intraoral application of HF for orthodontic treatment.

PURPOSE To investigate the influence of different cleaning methods for additively manufactured fixed dental prostheses (FDPs) for long-term temporary use on the degree of conversion (DC), surface roughness, Martens parameters, and biaxial flexural strength. MATERIALS AND METHODS A total of 180 specimens per material (3Delta Etemp, DeltaMed; Freeprint Temp, Detax; Temp PRINT, GC Europe; Temp CB N = 180) were additively manufactured (D20 II, Rapid Shape) and subsequently cleaned by different methods: by rinsing for 5 minutes in acetone (Hofer Chemie; 99.5%); butyl glycol (Algin Chemie; 100%); ethanol (Otto Fischar; 96%); isopropanol (SAV LP; 100%); Yellow Magic 7 (Bradley Systems; 100%); or by applying centrifugal force for 4 minutes (n = 30 per subgroup). After postpolymerization (Otoflash G171, NK-Optik), the DC was measured using Raman spectroscopy, and the surface roughness, as well as the Martens parameters, were recorded. Biaxial flexural strength was investigated after artificial aging (thermocycling for 10,000 cycles). Data were statistically analyzed (Kolmogorov-Smirnov, Kruskal-Wallis, and Mann-Whitney U tests, and Pearson correlation coefficient). RESULTS The highest DC was recorded after the use of butyl glycol or isopropyl (P < .001 to P = .047). The highest surface roughness was measured after the use of butyl glycol (P < .001 to P = .024). The use of centrifugal force or Yellow Magic resulted in the highest Martens parameter values (P < .001 to P = .036) and the highest biaxial flexural strength (P < .001 to P = .013), while acetone and butyl glycol led to the lowest values. CONCLUSION The use of centrifugal force and Yellow Magic resulted in the highest Martens parameter values and the highest biaxial flexural strength. Concerning Yellow Magic, no negative effect on the mechanical properties was observed. The 3Delta Etemp material especially was prone to degradation after chemical cleaning.

Objective To investigate the degree of conversion (DC), Martens hardness (HM), elastic indentation modulus (EIT), and biaxial flexural strength (BFS) of six dual-polymerizing resin composite luting materials initially and after 2 and 7 days of aging. Materials and methods Specimens fabricated from Bifix QM (BIF; VOCO), Calibra Ceram (CAL; Dentsply Sirona), DuoCem (DUO; Coltène/Whaledent), G-CEM LinkForce (GCE; GC Europe), PANAVIA V5 (PAN; Kuraray Europe), and Variolink Esthetic DC (VAR; Ivoclar Vivadent) (n = 12 per material) were light-polymerized through 1 mm thick discs (Celtra Duo, Dentsply Sirona). DC, HM, and EIT were recorded directly after fabrication, and after 2 and 7 days of aging. As a final test, BFS was measured. Univariate ANOVAs, Kruskal–Wallis, Mann–Whitney U, Friedman, and Wilcoxon tests, and Weibull modulus were computed (p Results While CAL presented low DC, HM, EIT, and BFS values, DUO and BIF showed high results. Highest Weibull moduli were observed for VAR and DUO. DC and Martens parameters increased between the initial measurement and 2 days of aging, while aging for 7 days provided no further improvement. Conclusions The choice of dual-polymerizing resin composite luting material plays an important role regarding chemical and mechanical properties, especially with patients sensitive to toxicological issues. DUO may be recommended for bonding fixed dental prostheses, as it demonstrated significantly highest and reliable results regarding DC, HM, and BFS. As DC and HM showed an increase in the first 48 h, it may be assumed that the polymerization reaction is not completed directly after initial polymerization, which is of practical importance to dentists and patients. Clinical relevance The chemical and mechanical properties of dual-polymerizing resin composite luting materials influence the overall stability and long-term performance of the restoration.

New materials and precise manufacturing processes allow for new processes in the veneering and production of fixed dental prostheses. However, data on the bond strength of computer-aided design and computer-aided manufacturing (CAD-CAM) and conventional veneering materials to substrates bonded with different composite resins are lacking.The purpose of this in vitro study was to investigate the shear bond strength (SBS) of 2 CAD-CAM, Lava Ultimate (LVU) and VITABLOCS Mark II (VMII), and 3 conventional veneering materials (VM9, VM13, VTI) to 3 different substrates: zirconia (ZIR), cobalt-chromium (CC), and titanium (TIT).Substrates and veneering cylinders were manufactured and bonded by using 3 different composite resins, RelyX Unicem (RUL), RelyX Ultimate (RXU), and Sinfony (SIN), after various pretreatments (n=18). Half the specimens underwent artificial aging before SBS testing, and failure types were analyzed. Univariate 1-way ANOVA, Kruskal-Wallis, and Mann-Whitney U were computed (α=.05).CC substrates bonded with RUL showed the highest SBS (P=.007). ZIR substrates bonded with RXU presented higher SBS than TIT substrates (P=.007). ZIR substrates bonded with SIN showed higher SBS than CC substrates (P.001). SIN veneered groups showed lower SBS than that observed for VM9/13/VTI (P.001). SIN veneered LVU and VMII substrates presented lower SBS (P.001). Thermocycling led to a reduction in SBS for most groups (P=.001-.022). SIN veneered substrates and RXU veneered VMII substrates resulted in lower SBS than that seen for VM9/13/VTI and veneered ZIR substrates bonded with SIN or RXU (P.001). Adhesive failures were most common.While RUL is capable of forming a stable bond to CC without pretreatment, ZIR substrates achieve higher SBS after conditioning with an MDP-containing primer when using RXU or SIN than that seen for RUL. Pretreated CAD-CAM-veneered ZIR substrates bonded with SIN or RXU led to similar SBS results to those observed for conventional veneers, while veneering with SIN resulted in lower SBS.

To investigate the degree of conversion (DC), Martens hardness (HM), elastic indentation modulus (EIT), and flexural strength (FS) of veneering resin composites (SR Nexco Paste (NP), Ceramage Incisal (CI), Gradia Plus (GP); n=60/group) cured with different polymerization devices (bre.Lux Power Unit, Labolight DUO, Otoflash G171, LC-3DPrint Box, PCU LED; n=12/subgroup) after storage. Otoflash G171 and Labolight DUO showed increased DC/HM/EIT. CI presented the lowest DC and highest HM/EIT. NP showed the highest DC and lowest HM/EIT. Within Otoflash G171, Laboligth DUO and PCU LED, highest FS was observed for CI. Storage did not affect DC/HM/EIT for specimens cured with Otoflash G171 or Labolight DUO. With storage not showing an influence on the tested parameters for polymerization devices that otherwise presented superior results, increased storage time cannot be recommended. For the tested resin composites, this study observed a high/low degree of conversion to coincide with respectively low/high amounts of fillers/mechanical properties.

Statement of problem Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) materials of different formulations (3Y-TZP, 4Y-TZP, and 5Y-TZP) can be colored by using color liquids. However, practically and clinically relevant factors such as modifications of sintering protocols and hydrothermal aging might affect the extent of light transmittance and flexural strength of zirconia materials of different formulations; studies on these outcomes, however, are lacking. Purpose The purpose of this in vitro study was to test the impact of hydrothermal aging on the light transmittance and flexural strength of colored zirconia materials compared with a lithium-disilicate (LiSi2) ceramic. Material and methods A total of 210 specimens were prepared from 3Y-TZP0.25 (n=30), 3Y-TZP0.05 (n=30), 5Y-TZP (n=30), 4Y-TZP (n=60), pre4Y-TZP (preshaded, n=30), and LiSi2 (n=30). All specimens, except for pre4Y-TZP and LiSi2, were manually colored, predried, and either conventionally sintered at 1450 °C (3Y-TZP0.25, 3Y-TZP0.05, 5Y-TZP, and half of 4Y-TZP) or high-speed sintered at 1580 °C (other half of 4Y-TZP and pre4Y-TZP). Light transmittance was measured initially and after 2, 5, 10, 20, 40, and 160 hours of hydrothermal aging (134 °C, 0.2 MPa). Biaxial flexural strength was tested initially and after 160 hours of hydrothermal aging (n=15). The Kolmogorov-Smirnov test, multivariate analysis, and 1-way ANOVA with the Tukey HSD post hoc test, the t test, and linear mixed models were calculated (α=.05). Results LiSi2 showed the highest translucency, followed by 5Y-TZP, 4Y-TZP, pre4Y-TZPspeed, 3Y-TZP0.05, and 3Y-TZP0.25. 4Y-TZPspeed was most opaque and matte. The decrease in translucency related to aging hours was higher for LiS2 and conventional sintered zirconia materials than for 4Y-TZPspeed and pre4Y-TZPspeed. Initially, 3Y-TZP0.25 had the highest flexural strength, followed by 3Y-TZP0.05, 4Y-TZP, and pre4Y-TZPspeed. pre4Y-TZPspeed was comparable with 4Y-TZPspeed but significantly higher than 5Y-TZP. LiSi2 had the lowest biaxial flexural strength. Hydrothermal aging increased biaxial flexural strength for 3Y-TZP0.25 and 3Y-TZP0.05 (P Conclusions Manually colored, conventionally sintered 4Y-TZP was resistant to hydrothermal aging regarding flexural strength. High-speed sintering inhibited color development for manually colored 4Y-TZP but did not affect the resistance to hydrothermal aging. The findings were reversed for industrially preshaded 4Y-TZP.

Statement of problem The selection of an appropriate restorative material based on fracture behavior is important for the marginal integrity of a dental restoration. For computer-aided design and computer-aided manufacturing (CAD-CAM) restorative materials, information regarding their edge chipping resistance is scarce. Purpose The purpose of this in vitro study was to determine the edge chipping resistance (ECR) and Martens hardness (HM) of 6 different dental CAD-CAM restorative materials before and after thermocycling. Material and methods Four composite resin materials including Brilliant Crios; Cerasmart, an experimental material; Lava Ultimate, a polymer-infiltrated ceramic-network (PICN) material (VITA Enamic), and a glass-ceramic control (IPS Empress CAD) were tested. The specimens were tested before and after thermocycling (30 000 times, 5 °C/55 °C). The ECR was measured for each material (n=25) and related to the point of loading and to the maximum chipping depth. HM was determined for each material (n=25). The Kruskal-Wallis and Mann-Whitney U tests were used to compare materials (α=.05). The impact of thermocycling was analyzed by using the Wilcoxon test (α=.05). The correlations between all parameters were calculated by using the Spearman-Rho test (α=.05). For fractographic analysis of chip patterns, chipped surfaces were analyzed by laser scanning microscopy. Results For ECR and HM, the materials showed different values. ECRmd and ECRpl showed a positive correlation, but both showed a negative correlation to HM. The materials showed a different chip size (P Conclusions All tested CAD-CAM materials behaved as brittle materials, but HM and ECR differed among the materials. The control glass-ceramic material showed the highest values for HM, followed by the PICN material. ECR values revealed the opposite order of materials, with the highest for composite resins. Artificial aging by thermocycling affected all dental CAD-CAM restorative materials. Especially for composite resin materials, ECR changed after aging.

Statement of problem High-performance thermoplastics have been adopted as framework materials. However, their bond strength to an esthetic veneering material is unclear. Purpose The purpose of this in vitro study was to test the tensile bond strength (TBS) between an aryl-ketone polymer (Ultaire AKP) and veneering resins. Material and methods AKP substrates (N=324) were prepared, airborne-particle abraded (Al2O3, 50 μm, 0.2 MPa), and divided into 9 groups (n=36) with different bonding systems (visio.link, Adhese Universal, All-Bond Universal, CLEARFIL UNIVERSAL BOND, G-Premio BOND, iBOND Universal, ONE COAT 7 UNIVERSAL, Scotchbond Universal) and without a bonding system as a control. Each group was further divided for opaquer (n=18). Further subdivision followed according to flowable or paste veneering resin (n=9). Specimens were stored in distilled water for 24 hours at 37 °C and thermocycled (×5000, 5/55 °C). TBS was measured and analyzed with the Kolmogorov-Smirnov test and 3-way ANOVA with partial eta squared (ηP2), followed by the Kruskal-Wallis and Mann-Whitney-U tests. Relative frequency of failure types was analyzed with the Chi2-test and a Ciba-Geigy table. Results The highest impact on TBS was exerted by the adhesive (ηP2=0.458, P Conclusions The application of opaquer increased TBS for all universal adhesives. Using opaquer and flowable veneering resin is beneficial for bonding to Ultaire AKP.

Objectives To test and compare five pressable lithium-X-silicate-ceramics on their mechanical and wear properties. Methods Specimens were pressed and prepared from: i. Amber Press (AP), ii. Celtra Press (CP), iii. Initial LiSi Press (IL), iv. Livento Press (LP), and v. IPS e.max Press (IE). Four-point flexural strength (FS), SEVNB fracture toughness (KIC), three-body wear (3BW), Martens hardness (HM) and indentation modulus (EIT) were measured. For CP, FS and HM were measured with and without additional Power Firing. Each subgroup contained 15 specimens. Data were analyzed using Kolmogorov–Smirnov, one-way ANOVA followed by Scheffe test, Kruskal–Wallis-H-, Mann–Whitney-U-, and Spearman–Rho-test (p Results AP and CP presented higher FS than IL. LP presented the highest Weibull modulus. CP showed lower KIC values than AP, and AP was not significant compared to LP and IE. The most 3BW material loss was observed for CP. CP revealed higher HM values than the remaining ceramics. IL presented lower EIT compared to AP and CP. The following correlations were observed between the test parameters: 3BW with FS (r = 0.279, p = 0.015), with HM (r = −0.378, p = 0.001), and with EIT (r = −0.344, p = 0.004); EIT with FS (r = 0.203, p = 0.028); and HM with FT (r = −0.223, p = 0.027) and EIT (r = 0.884, p Significance AP followed by LP showed the highest and IL followed by CP the lowest properties tested. Power Firing of CP improved the flexural strength. Ceramics with high flexural strength and Martens parameters showed lower wear. Materials with high Martens hardness presented lower fracture toughness values and ones with high indentation modulus showed high flexural strength.

Objective This interlaboratory round robin test investigated the robustness of the Chevron-Notch Beam (CNB) test method and the effect of the processing and testing variations on the fracture toughness of a dental 3Y-TZP ceramic. Methods The round robin test was performed precisely following the procedures recommended in ISO 24370:2005 and applied on a commercial 3Y-TZP ceramic (product information). A total of 335 test specimens with dimensions 3×4 x 45 mm³ was equally distributed among 10 participating laboratories of varying experience in fracture toughness testing. A standard operating procedure was defined with either narrow processing tolerances or alternative (wider) processing tolerances (as proposed in ISO 24370). Fracture toughness data (series 2) was analyzed using one way ANOVA followed by post hoc Tukey HSD test and 95% Confidence Intervals (CI) were computed (p < 0.05). A further, preceding round-robin (series 1) test was conducted with - more possible variations of test conditions regarding CNB notch processing and storage conditions. Those results are summarized in the supplement and discussed with the actual ISO 24370 test. Results Fracture toughness of the 3Y-TZP ceramic material, summarized over all laboratories was measured to KIc = 4.48 ± 0.11 MPam0.5 for the standard processing tolerance and KIc = 4.55 ± 0.31 MPam0.5 for the alternative tolerance. The results revealed a significant influence of cutting offset and notch geometry on KIc when using CNB method. The test medium also has a significant influence on KIc in terms of reduced fracture toughness under the influence of water. With defined testing conditions the number of valid tests and reduced standard deviation increased. In case of strictly following such standard operation procedures, KIc can be determined with high reliability. There is no difference between the involved laboratories, but significant influence of cutting offset on KIC was observed. Significance The CNB method is suitable method for determination of KIc on fine-grained ceramics such as 3Y-TZP ceramic. By using tighter tolerances for processing and testing, i.e. closely following the ISO 24370 procedure, a highly-precise evaluation of fracture toughness with low data variation is achievable. The information of the storage medium should always be reported along with the data. CNB fracture toughness testing is an alternative method compared to Single-edge V-notch beam (SEVNB), especially for fine-grained ceramics.

PURPOSE To investigate the tensile bond strength between zirconia abutments and titanium bases, luted with two different resin composite cements, after different cleaning procedures. MATERIALS AND METHODS Zirconia abutments and titanium bases were luted with either a DMA/HEMA-based cement (n = 80; Multilink Hybrid Abutment, Ivoclar Vivadent) or a Bis-GMA/TEGDMA-based cement (n = 80; Panavia V5, Kuraray Noritake). The adhesive gap of half of the specimens was polished (n = 40 per resin composite cement). Four separate specimens underwent roughness measurements and scanning electron microscopy. The specimens were divided into four groups (n = 10 per subgroup): (1) not cleaned, (2) cleaning in an ultrasonic bath, (3) cleaning in an autoclave, and (4) treatment with low-pressure plasma. The specimens were thermocycled (20,000×, 5°C/55°C), tensile bond strength was tested, and fracture types were analyzed. Data were examined using the Kolmogorov-Smirnov test, univariate ANOVA with additional partial eta-squared (ηp2), and the Mann-Whitney U test. The defined level of significance was adjusted by Bonferroni correction (P < .003). RESULTS The tensile bond strength of specimens luted with the DMA/HEMA-based cement was higher than that of specimens luted with the Bis-GMA/TEGDMA-based cement. The polishing step and the cleaning procedures showed no impact on tensile bond strength results. Specimens luted with the DMA/HEMA-based cement presented more cohesive fractures, whereas specimens luted with the Bis-GMA/TEGDMA-based cement presented themselves with more fractures of the interface between the resin composite cement and zirconia abutment. Ra values showed a decline in roughness after polishing for both resin composite cements. CONCLUSION As the DMA/HEMA-based cement showed higher tensile bond strength values, the usage of this resin composite cement for luting implant abutments to titanium bases can be recommended. Neither polishing nor the use of different cleaning procedures had an impact on tensile bond strength.

PURPOSE To assess surface characteristics and implant stability after implantoplasty performed by two different instrument sequences regarding material loss, surface roughness, and fracture load resistance. Additionally, operators' subjective experience during instrumentation and the damage to neighboring teeth were evaluated. MATERIALS AND METHODS Titanium implants were placed in the position of both first maxillary molars in models exposing 6 mm of their surface. Implantoplasty was performed in phantom heads: Exposed surfaces were instrumented with diamonds and Arkansas stones or abrasive stones and silicone polishers. Operators reported on abrasion, gloss, effectiveness, and tactility using a visual analog scale (VAS). Residual wall thickness of implants was measured on radiographs, material abrasion using three-dimensional (3D) scans, and surface roughness by contact profilometry. Maximum bending moments were measured. RESULTS Residual thickness and weight loss were comparable after both treatments (0.3 ± 0.1 and 0.25 ± 0.07 mm and 0.22 ± 0.01 g, and 0.03 ± 0.01 mm and 0.02 ± 0.01 g, respectively, P > .05). Mean surface roughness was lower (P = .0001) for the group with the silicone polishers (0.4 ± 0.2 μm) compared with the group employing diamonds (0.8 ± 0.1 μm). Maximum bending moments showed neither intergroup differences nor stability loss compared with untreated implants. The stone-and-silicone polisher group showed less abrasion (4.6 ± 2.2) and higher gloss values (8.1 ± 1.4) than the diamond-and-Arkansas group (3.1 ± 1.3 and 4.1 ± 2.1, respectively). Superficial tooth injuries at proximal neighbor teeth were common (73% and 80%). CONCLUSION Implantoplasty did not weaken implant stability. The use of silicone polishers revealed lower surface roughness. Regarding surface smoothness, the instrumentation sequence employing silicon carbide and Arkansas stones followed by silicone polishers seems to be superior to the combination of diamond and Arkansas stones.

Objective To test the impact of zirconia pretreatment and aging on flexural strength and phase structure. Methods For flexural strength measurements, 180 3Y-TZP0.25 specimens were fabricated and pretreated: (i) air-abraded (105-μm alumina, 0.25 MPa), (ii) air-abraded (50-μm alumina, 0.25 MPa), (iii) air-abraded (30-μm silica-coated alumina, 0.28 MPa) (iv) non-pretreated. Each pretreated group (n = 15) was aged: (a) hydrothermal (134 °C, 0.23 MPa, 2 h) (b) in a mastication simulator (1,200,000×, 5/55 °C) and (c) not aged. The fractured specimens were stored dry for 5 years (23 °C) for analysis of phase transformation. Additionally, specimens were fabricated from 3Y-TZP0.25 (n = 12) and 3Y-TZP0.05 (n = 8), pretreated (i, ii, iii, iv), and hydrothermally aged. Each air-abrasion method was alternated using 0.05, 0.25 and 0.4 MPa pressure. The phase transformation was examined by Raman spectroscopy and surface topography by scanning electron microscope. Data were analyzed using univariate ANOVA with the Scheffe post hoc test and partial-eta-squared (ƞp²) (α = 0.05). Results The highest impact on flexural strength was exerted by the pretreatment (ηP² = 0.261, p Significance Air-abrasion with 30-μm silica-coated alumina powder can be recommended for pretreatment of 3Y-TZP0.25 and 3Y-TZP0.05. For air-abrasion using alumina powder lower pressure should be used.

To test the impact of polishing strategies on zirconia properties. One hundred eight zirconia specimens were divided into nine groups (n = 12/group). Seven groups were polished in the white-stage with either (1) a felt wheel (FW), (2) a felt wheel combined with a polishing paste (FWP), (3) a goat hair brush (GB), (4) a goat hair brush combined with a polishing paste (GBP), (5) a green-state finishing kit (FK), (6) a universal polisher (UP), or (7) with SiC polishing paper (PP), and sintered. Thereafter, the seven groups were divided into two subgroups each and polished using (1) a fine polisher (one-step, n = 6) or (2) a rough and fine polisher (two-steps, n = 6). The positive control group (polish-lab-kit, PLK) was sintered and polished in two-steps. The no polished group (NP) acted as negative control group. Translucency (T%) was measured after white-stage polishing and sintering, and after sintered-stage polishing. Surface free energy (SFE), surface roughness (SR), and flexural strength (FS) were determined. Data were analyzed using one-way ANOVA with Tukey-B post-hoc, t test, and Wilcoxon-test (p

To investigate the impact of pretreatment and conditioning on shear bond strength (SBS), surface free energy (SFE) and surface roughness (SR) between polyetheretherketone (PEEK) and cold-cured polymethylmethacrylate (PMMA).PEEK substrates (Dentokeep PEEK Disc, nt-trading) were air abraded with Al2O3 particles of different grain sizes applied with varying pressure at 1) 0.2 MPa - 50 µm Al2O3; 2) 0.4 MPa - 50 µm Al2O3; 3) 0.2 MPa - 110 µm Al2O3; 4) 0.4 MPa - 110 µm Al2O3; or 5) without air abrasion (n = 172/group). Surface properties were quantified using SFE and SR (n = 10/group), and scanning electron microscope imaging (n = 2/group). Substrates were conditioned with a) Visio .link (VL, Bredent); b) Scotchbond Universal (SU, 3M Oral Care); c) Bonding Fluid (BF, Schütz Dental); or d) without conditioning (WC; n = 40/subgroup) and bonded to the polymer (Futura Jet, Schütz Dental). SBS and fracture types were determined before and after 10,000 thermal cycles (n = 20/subgroup). Univariate ANOVA, Kruskal-Wallis test, Mann-Whitney U-test, Kaplan-Meier survival estimates, and Weibull distribution were computed (p0.05). Ciba-Geigy tables and the chi-squared test were used to analyze fracture type distributions.An increase in particle size and pressure resulted in similar or increased SBS, Weibull characteristic strength, and Weibull moduli (p0.001 - 0.046). The lowest results were observed for the control group (without air abrasion), while pretreatment with 0.4 MPa - 110 µm Al2O3 presented the highest values (p0.001). In comparison with the other conditioning procedures, VL showed high (p0.001 - 0.03), and SU and WC low SBS (p0.001 - 0.006). Although it did not influence SFE, an increase in particle size and pressure led to an increased SR (p0.001).Pretreatment with 0.4 MPa - 110 µm Al2O3 can be recommended to increase bonding properties between PEEK and PMMA. Application of adhesives such as VL can enhance SBS further.

OBJECTIVE To analyze the impact of the color of a resin composite cement (RCC) on the optical properties of different computer-aided design and computer-aided manufacturing (CAD/CAM) ceramics. MATERIALS AND METHODS Specimens (N = 220, thickness: 0.9 ± 0.03 mm) were fabricated from: leucite (Initial LRF Block/IPS Empress CAD), lithium disilicate (Amber Mill/IPS e.max CAD), lithium metasilicate (Celtra Duo), and lithium alumina silicate ceramic (n!ce) in translucency levels HT and LT. All specimens were bonded with an RCC (Light+/Warm+). Color was analyzed (spectrophotometer) initially as well as after bonding of RCC with CAD/CAM ceramics using CIELab and CIEDE2000. Kolmogorov-Smirnov test, one-way ANOVA and t test served for analyzing (α = 0.05). RESULTS Highest impact on ΔE presented the choice of ceramic (ηp2 = 0.155/p

Purpose Evaluation of the effect of three different dynamic fatigue protocols on the fracture resistance of two monolithic strength-gradient zirconia materials. Materials and methods A total of 240 specimens (3 × 4 × 45 mm) was milled from two different layers (incisal and middle) of two types of strength-gradient zirconia blanks (IPS e. max ZirCAD MT Multi A2 vs. IPS e. max ZirCAD Prime A2), resulting in 60 specimens per material and layer group (IPS e. max ZirCAD MT Multi A2: incisal (MI), middle (MM); IPS e. max ZirCAD Prime A2: incisal (PI), middle (PM)). Each group was divided into one static (n = 15) and three dynamic fatigue protocols (N = 45, n = 15): i. 50 N increase every 5000 cycles ii. Increase by 5% of static fracture load every 5000 cycles iii. 10 N increase every 1000 cycles until facture. All specimens were loaded until facture in CeraTest 2 k. Kaplan-Meier, Log-Rank and Chi-squared-test as well as Weibull statistics were performed. A fractographic analysis was performed. The specimens were classified according to the number of crack origins and evaluated using the Ciba-Geigy table. Results With regard to the fracture load, in the static loading MI and PI showed a higher fracture load and in dynamic fatigue protocol 2 PI showed a lower fracture load. The number of cycles until fracture only differed within three groups: MM and MI survived a higher number of cycles in dynamic fatigue protocol 2; PI survived a higher number of cycles in dynamic fatigue protocol 2 than in protocol 1. Within dynamic fatigue protocols, PM resisted the highest number of cycles in protocol 1 and 3 and MI in protocol 2. Comparing groups, Weibull modulus differed only within the static loading, with PI showing lower values than MM and MI. Within the material groups, MI showed higher values in static loading than in dynamic fatigue protocol 1 and 2, and PI showed higher values in the dynamic fatigue protocol 3 than in static loading. With regard to fracture patterns, no differences were found between the groups. Conclusions Dynamic fatigue protocols provide clinically relevant information on the long-term stability and reliability of monolithic strength-gradient zirconia materials. However, no definitive instructions for dynamic testing can be provided from this investigation.

Objective The aim of this interlaboratory round robin test was to prove the robustness of the DIN EN ISO 6872:2019 and to identify the influence of processing and testing variations. Methods Each of the 12 laboratories participated (A–L) received 60 (n = 720) assigned zirconia specimens. All participants seperated the specimens from the blanks, sintered them, polished half of all specimens and performed the biaxial flexural test (DIN EN ISO 6872:2019). The surface roughness was determined by using tactile measuring device. Fractographic examination was performed under scanning-electron-microscopy (SEM). Data was analysed using Kolmogorov–Smirnov-, Kruskal–Wallis-, Mann–Whitney-U-test and two-parametric Weibull statistic (p Results The results for both preparation methods (as-fired and polished) showed significant differences for some participants. The values for as-fired groups ranged between 513 (I) and 659 (E) MPa. H showed higher Weibull modulus than C, E and I. Within polished groups flexural strengths values from 465 (L) to 1212 (E) MPa were observed, with a tendency to clustered groups A, I, J, L (465–689 MPa) and remaining groups (877–1212 MPa). E presented the highest and H the lowest Weibull modulus. Within A and J, no impact of the preparation method on flexural strength values was observed. Within L, as-fired specimens showed higher flexural strength than polished ones. The flexural strength increase did only associate to a certain extent with measured surface roughness. Fractography showed defect populations depending on polishing techniques, associated to the strength level, especially for polished groups. Reduced strength is related to machining defects, regardless of the surface state. Significance DIN EN ISO 6872:2019 can be seen as guidance to biaxial flexural strength testing but additional effort is necessary to ensure interlaboratory comparability. Calibrated furnaces and reliable sintering conditions are mandatory requirements together with detailed specifications on finishing or polishing procedures. Biaxial flexural testing is really a matter of understanding specimen preparation, alignment and mechanical testing by itself. DIN EN ISO 6872:2019 should further recommend reporting of mean surface roughness along with any biaxial flexural strength data. Fractography is a mandatory tool in interpretation and understanding of strength data.

This study tested and compared properties of six modern indirect veneering resin composites (VRC), namely Ceramage (Shofu), dialog Vario (Schutz Dental), Gradia Plus (GC Europe), in:joy (Dentsply), Signum composite (Heraeus Kulzer), and SR Nexco (Ivoclar Vivadent). Specimens were fabricated from dentin and enamel pastes and following properties were analyzed: (1) two-body wear (TB), (2) surface roughness (SR), (3) Martens hardness parameters (HM and EIT), and (4) translucency (T). The highest impact on HM and EIT was exerted by VRC brand (HM: ηP2=0.960/ EIT: ηP2=0.968; p

Objective To test the impact of three varying step-stress protocols on the fatigue behavior of two 3Y-TZP, one 4Y-TZP and one 5Y-TZP zirconia materials. Methods Eight specimens per zirconia material (N = 32) were selected for static testing to determine the start load for dynamic tests (30% of the mean value of static fracture load). 45 specimens per material (N = 180) were used for dynamic load tests using three step-stress protocols: 1. 50 N/5000 cycles; 2. 5% of static load/5000 cycles, and 3. 10 N/1000 cycles. Following materials were tested: 3Y-TZP( Results The step-stress protocols showed no impact on the fracture load or Weibull modulus within one zirconia material. However, the zirconia materials T, ET and HT showed differences in cycle number to fracture between the step-stress protocols (T: 3 > 2 > 1; ET: 2 > 3 > 1; HT: 2, 3 > 1) with lowest cycle number to fracture for protocol 1. Within one step-stress protocol, the cycle number to fracture varied according to the zirconia material as follows: 1: T, O ≥ O, ET > HT; 2: ET > O, T, HT; 3: O, T, ET > HT. Cracking started at the tensile side of the specimens at all times. All specimens showed typical compression curls (single or double). Fragmentation patterns were similar for all materials with a lot of crack branching and fragmentation due to secondary cracks indicating high energy fractures. Significance Dynamic fatigue tests seem to provide important information on the long-term stability of zirconia materials. Zirconia materials with higher opacity seem to be more robust towards varying step-stress protocols than translucent zirconia materials. Regarding expenditure of time, a step-stress protocol with a load increase of 50 N every 5000 cycles seems favorable to gain information on the long-term stability of zirconia materials.

Objectives To investigate the edge chipping resistance (ECR) of six veneering composite resins after different treatment protocols. Materials and methods Rectangular bar specimens were manufactured from Ceramage Incisal (CER; Shofu), dialog Vario Occlusal (DIA; Schutz Dental), Gradia Plus Heavy Body Enamel (GRA; GC Europe), in:joy incisal (INJ; Dentsply Sirona Deutschland), SR Nexco Paste Incisal (SRN; Ivoclar Vivadent), and Signum composite enamel (SIG; Kulzer). ECR was determined after five treatment protocols: (1) no treatment, (2) after storage in distilled water at 37 °C for 7 days, (3) storage in distilled water with an additional 10 000 thermal cycles (5 °C/55 °C), and hydrothermal treatment at 134 °C at a water vapor pressure of 0.2 MPa for a duration of (4) 3.5 min or (5) 23.5 min. Force was applied with the universal testing machine ZHU 0.2 (Zwick Roell) mounted with a Vickers diamond indenter until the chip fractured off the specimen and ECR values were computed by dividing the applied maximum force by the distance to the center of the applied force. Fracture analysis was performed employing light microscope imaging. Univariate and one-way ANOVA, Scheffe and Tukey-B post hoc, and partial eta squared (ƞp2) were computed (p Results DIA presented consistently high ECR values, while CER showed low results. For some groups, seven days’ storage in water and hydrothermal treatment for 3.5 min led to higher ECR results than observed in the initial state, while an additional 10 000 thermal cycles and hydrothermal treatment for 23.5 min resulted in lower ECR values. Conclusions The examined veneering composite resins differed in regard to their mechanical properties, with DIA possessing the highest resistance to chipping. While post-processing can initially increase a material's edge chipping resistance, intensified treatment protocols reduced the mechanical properties of veneering composite resins.

The purpose of this study was to analyze the impact of plasma treatment and (universal adhesives) UAs on the bonding properties of zirconia. Zirconia specimens (N = 744; n = 186/pretreatment) were prepared, highly polished, and pretreated: (i) plasma (oxygen plasma, 10s, 5 mm), (ii) airborne-particle abrasion (alumina, 50 μm, 0.05 MPa, 5 s, 10 mm), (iii) airborne-particle abrasion + plasma, and (iv) without pretreatment (highly polished surface). Surface roughness (Ra) and surface free energy (SFE) were measured (n = 6/pretreatment). Tensile bond strength (TBS) specimens (n = 180/pretreatment) were further divided (n = 18/conditioning): Clearfil Ceramic Primer (PCG), All-Bond Universal (ABU), Adhese Universal (AU), Clearfil Universal Bond (CUB), G-Premio Bond (GPB), Futurabond U (FBU), iBond Universal (IBU), One Coat 7 Universal (OCU), Scotchbond Universal (SBU), and no conditioning. PCG was luted with Panavia F2.0 and the remaining groups with DuoCem. After storage in distilled water (24 h; 37 °C) and thermocycling (5000×; 5 °C/55 °C), TBS was measured and fracture types (FTs) were determined. Data were analyzed using univariate ANOVA with a partial eta square (ƞP2), the Kruskal–Wallis H, the Mann–Whitney U, and the Chi2 test (P

Objectives To investigate and compare the mechanical and optical properties of novel strength- and color-gradient multilayered zirconia and the impact of conventional and high-speed sintering. Materials and methods Following zirconia materials were analyzed and compared: the high-speed sintered Katana Zirconia Block STML (4Y-TZP, KZC), the conventionally sintered Katana Zirconia Disc STML (4Y-TZP, KZL) and IPS e. max ZirCAD Prime (5Y-TZP/3Y-TZP, EZL). As control group acted the crystallized lithium disilicate ceramic IPS e. max CAD (ELC). Monolithic single molar crowns were fabricated and half of them were aged in a chewing simulator with human enamel antagonists (1.2 × 106 cycles, 50 N, lateral movement of 0.7 mm, 5/55 °C). The fracture load was tested in a universal testing machine (N = 96/n = 12). The two-body wear was determined using 3D matching of pre- and post-scans (N = 48/n = 12). Translucency (N = 36/n = 10) was evaluated with UV/Vis spectrophotometer. Data was analyzed using Kolmogorov-Smirnov test, one-way ANOVA followed by post-hoc Scheffe test, unpaired t-test and Weibull analysis (p Results Zirconia groups showed higher fracture load than ELC (p ≤ 0.001). Initially, all zirconia materials ranged in the same values (p > 0.05). After chewing simulation, EZL showed higher fracture load than KZC (p Conclusions The novel strength and color-gradient multilayered zirconia showed higher mechanical properties than lithium disilicate ceramic. The high-speed sintering of zirconia showed neither a negative impact on the fracture load nor on the two-body wear. However, the optical properties and the reliability of zirconia is lower than those of highly translucent lithium disilicate ceramic.

Testing and comparing of different non-shaded zirconia materials (3Y-TZP, 4Y-TZP and 5Y-TZP) on optical and mechanical properties.Zirconia materials (N = 320, Opaque O, Translucent T, Extra Translucent ET, High Translucent HT) were investigated on translucency, Martens parameter, biaxial flexural strength, Chevron-Notch-Beam (CNB) fracture toughness (KThe translucency of ET and HT increased with the thermo-mechanical aging (p 0.001). The zirconia material and aging had no impact on the Martens hardness and the indentation modulus. ET showed the highest flexural strength values after initial and thermo-mechanical aging (p 0.001 - 0.683). All four materials showed the highest flexural strength after thermo-mechanical aging after 1.2 Mio cycles. Thermo-mechanically (1.2 Mio cycles) aged HT presented the highest Weibull modulus (m = 15.0) regardless of aging. Within initial groups, T (p ≤ 0.001) showed the highest fracture toughness, followed by O (p ≤ 0.001), ET (p 0.003) and HT (p ≤ 0.001).Translucency of ET and HT increases with thermo-mechanical aging. Chevron-Notch-Beam (CNB) is a valid alternative to the single-edge-V-notched beam (SEVNB) method for testing fracture toughness.

OBJECTIVES This investigation evaluated the impact of multiple firings during the veneering process of all-ceramic restorations on the thermal properties and bond strength between veneering ceramics and zirconia. METHODS For the measurements of the coefficient of thermal expansion (CTE) prismatic specimens of four different veneering ceramics (ZRT/ZRO/HFZ/STR; N��=��40/n��=��10 per veneering ceramic) and rod-shaped zirconia specimens (N��=��2) were produced. 2 specimens of each veneering ceramic were fired 2, 4, 6, 8, and 10 times simulating dentine-firing. Measurements were performed in a dilatometer and glass transition temperature (Tg) was determined graphically. To analyze bond strength (BS), crack initiation test specimens were prepared using the same veneering ceramics and zirconia (N��=��600/n��=��150 per veneering ceramic). 30 specimens of each veneering ceramic were fired 2, 4, 6, 8, and 10 times. Half of them were thermocycled (5000 cycles, 5����C/55����C, 20s). The crack initiation test was conducted in a universal testing machine. Data was analyzed using ANOVA with partial eta squared statistics and post-hoc Scheff�� test as well as Pearson correlation test. RESULTS CTE was mostly affected by the choice of veneering ceramic (p��

Statement of problem The development of zirconia materials with optimized properties has been rapid, and studies comparing the mechanical and optical properties of recently introduced zirconia with lithium disilicate materials are limited. Purpose The purpose of this in vitro study was to compare the mechanical and optical properties of cubic/tetragonal zirconia materials with those of a lithium disilicate ceramic. Material and methods Specimens were fabricated from 6 different noncolored zirconia materials: Ceramill Zolid FX (CZ), CopraSmile (CS), DD cubeX2 (DD), NOVAZIR MaxT (NZ), priti multidisc ZrO₂ (PD), and StarCeram Z-Smile (SC), and 1 lithium disilicate ceramic as a control, IPS e.max Press LT A2 (CG). Four-point flexural strength (N=105/n=15) and fracture toughness using the single-edge V-notched beam (N=105/n=15) were examined according to International Organization for Standardization standard 6872:2015. Translucency (N=70/n=10) was evaluated with an ultraviolet spectrophotometer. Grain size (N=6/n=1) of zirconia was investigated by using scanning electron microscopy. Data were analyzed using the Kolmogorov-Smirnov test, multivariate analysis, 1-way analysis of variance, followed by the post hoc Scheffe test and Kruskal-Wallis and Mann-Whitney U tests, and Weibull analysis, using the maximum likelihood estimation method at 95% confidence level (α=.05). Results Zirconia materials showed higher mechanical and lower optical properties than CG (P Conclusions Cubic/tetragonal zirconia showed better mechanical properties than lithium disilicate ceramic. However, the optical properties and the reliability of zirconia are lower than those of lithium disilicate ceramic.

Objective : This study investigated the influence of postpolymerization of a three-dimensional (3D) printed denture base polymer. The effect of post-curing methods on surface characteristics, flexural strength, and cytotoxicity was evaluated. Methods : A total of 172 specimens were additively manufactured using one denture base material (V-Print dentbase, VOCO) and further post-cured by different light-curing devices, including Otoflash G171 (OF), Labolight DUO (LL), PCU LED (PCU), and LC-3DPrintbox (PB), respectively. Polymethyl methacrylate resin (PalaExpress Ultra) was used as a reference (REF). Afterward, surface topography was observed using scanning electron microscopy, and surface roughness was measured (n = 6). Furthermore, flexural strength was tested (n = 20). Cytotoxicity was evaluated by the extract and direct contact tests. The data were analyzed using the Kolmogorov-Smirnov test and one-way ANOVA followed by Tukey's multiple comparisons and Kruskal-Wallis tests (p Results : The different post-curing methods applied did not significantly influence surface topography and roughness (Ra). Meanwhile, specimens post-cured by PCU (162.3 ± 44.16 MPa) and PB (171.2 ± 34.41 MPa) showed significantly higher flexural strength than those post-cured by OF (131.3 ± 32.87 MPa) and REF (131.2 ± 19.19 MPa), respectively. Additionally, various post-curing methods effectively decreased the cytotoxic effects of 3D-printed denture base polymer. Conclusions : Different post-curing methods did not significantly alter the Ra values of the 3D-printed denture base material. However, flexural strength was significantly affected by the postpolymerization methods, which might be attributed to the different wavelengths of post-curing devices. In addition, various postpolymerization methods reduced the cytotoxic effects of the 3D-printed denture base polymer. Clinical Significance : Flexural strength of additively manufactured denture bases depends on the postpolymerization strategy. Therefore, an appropriate post-curing method is required to optimize the flexural strength of 3D-printed denture materials.

Objective The aim of this study was to investigate the impact of a heating/quenching process on the optical, mechanical and thermodynamic properties of filled (20%_4000) and unfilled PEEK films (0%_2000 and 0%_4000). Heating/quenching was performed to simulate thermoforming as possible method to process thermoplastic polymers for dental application. Methods For the investigation, films of different PEEK qualities (0%_2000, 0%_4000, 20%_4000) were produced using isostatic pressing (n = 10/quality). From each PEEK film, round specimens (n = 20/PEEK film) with a diameter of 34 mm were cut and following parameters were determined: translucency (T%), Martens-Hardness (HM), indentation modulus (EIT), glass transition temperature (TG), melting temperature (TM) and enthalpy of fusion (ΔHf). Same specimens were exposed to heating/quenching using defined parameters. Afterwards, T%, HM, EIT, TG, TM and ΔHf were determined again. Data were analysed using Kolmogorov–Smirnov test, univariate ANOVA followed by post-hoc Scheffe test with partial eta squared (ηp2), Kruskal–Wallis and Mann Whitney U test. Level of significance was defined to 95%. Results Materials showed significant differences for all investigated parameters in the initial state, except of TG (p = 0.249). The heating/quenching process showed a significant increase on T% for the unfilled materials 0%_2000 and 0%_4000. HM and EIT decreased significantly through heating/quenching for all materials. Moreover, heating/quenching showed a reduction of TG for 0%_2000 and 20%_4000, while TM decreased for 0%_2000 and 0%_4000. ΔHf confirms different crystallinities of tested materials. Significance The heating/quenching process showed a significant impact on all investigated parameters. The highest impact was found for mechanical properties resulting in decreased values of HM and EIT.

The objective of the study was to investigate the tensile bond strength (TBS) to polyaryletheretherketone (PEEK) after different pretreatment and conditioning methods. Four hundred PEEK specimens were fabricated and allocated to the following air-abrasion methods (n 1 = 80/pretreatment): (i) 50 μm Al2O3 (0.05 MPa); (ii) 50 μm Al2O3 (0.35 MPa); (iii) 110 μm Al2O3 (0.05 MPa); (iv) 110 μm Al2O3 (0.35 MPa); and (v) Rocatec 110 μm (0.28 MPa). These pretreatments were combined with the following conditioning methods (n 2 = 20/pretreatment/conditioning): (a) visio.link (VL); (b) Monobond Plus/Heliobond (MH); (c) Scotchbond Universal (SU); and (d) dialog bonding fluid (DB). After veneering of all specimens with dialog occlusal and aging (28 days H2O, 37 °C + 20,000 thermal cycles, 5/55 °C), TBS was measured. Data was analysed using Kaplan–Meier survival analysis with Breslow–Gehan test and Cox-regressions. The major impact on TBS showed the conditioning, followed by the air-abrasion-pressure, while the grain size of the air-abrasion powder did not show any effect. Specimens air-abraded at 0.35 MPa showed the highest survival rates. However, within VL groups, this observation was not statistically significant. Within MH groups, pretreatment using 110 μm Al2O3 and 0.05 MPa resulted in higher survival rates compared to groups treated with 50 and 110 μm Al2O3 using a pressure of 0.35 MPa. The use of VL showed the highest survival rates between the adhesive systems and the TBS values higher than 25 MPa independent of the pretreatment method. As an exception, only VL showed significantly higher survival rates when compared to MH. The adequate choice of the adhesive system and higher pressures improved the TBS between PEEK and veneering resin composite. The particle size had no major impact. According to this study, best veneering of PEEK with dialog occlusal can be achieved by conditioning with visio.link in combination with the pretreatment of airborne particle abrasion at a pressure of 0.35 MPa.

Elastic properties of Aryl-Ketone-Polymer (UAKP) and tensile bond strength (TBS) to denture resin (PalaXpress) were tested. Indentation modulus (EIT) and indentation hardness (HIT) were measured via Martens hardness (n=10 specimens) with 4.2±0.6 kN/mm2 and 261±8 N/mm2 respectively. TBS was tested in dependence of different adhesives (visio.link (VL), Adhese Universal (AU), All-Bond Universal (ABU), CLEARFIL UNIVERSAL BOND (CUB), G-Premio BOND (GPB), iBOND Universal (IBU), ONE COAT 7 UNIVERSAL (OCU), Scotchbond Universal (SBU) and without adhesive (CG), n=18/group) and the application of opaquer (n=9/group) after thermocycling (5°C/55°C, 10,000×). TBS was affected by the adhesive (η (P2=0.715, p

To investigate the influence of high-speed and conventional sintering on the flexural strength (FS) of three zirconia materials initial and after artificial aging.Milled zirconia specimens (3Y-TZP: ZI and Zolid; 4Y-TZP: Zolid HT+; Amann Girrbach AG; N = 288, n = 96/group) were sintered in a high-speed sintering protocol (final temperature 1580 °C, n = 48/subgroup) or a conventional sintering protocol (control group, final temperature 1450 °C, n = 48/subgroup). FS was tested initially and after artificial aging (10 h in an autoclave or 1,200,000 chewing cycles; n = 16/subgroup). Univariate ANOVAs, post-hoc Scheffé, partial eta-squared, Kolmogorov-Smirnov-, Kruskal-Wallis- and Mann-Whitney-U-test were performed (p0.05).ZI showed the highest and HT+ the lowest FS, regardless of the sintering protocols and aging regimens (p0.001). High-speed sintered HT+ showed higher initial FS than the control group (p0.001). ZI (p0.001-0.004) and Zolid (p0.001-0.007) showed higher FS after thermo-mechanical aging. High-speed sintered HT+ showed higher FS in the initial stage (p0.001). The Weibull modulus of the three thermo-mechanically aged materials was negatively influenced by high-speed sintering.As shorter sintering times represent a cost and time efficient alternative, high-speed sintering is a valid alternative to conventional sintering protocols.

Objective This investigation tested pre-shaded 3Y-TZP materials on optical, mechanical and structural properties and calculated correlations between these properties. Methods Seven A2-shaded 3Y-TZP zirconia materials were investigated on translucency (T) via UV–vis-spectrophotometer, fracture load of 3-unit FDPs (FL), biaxial flexural strength (FS), Chevron-Notch Beam (CNB), fracture toughness (KIC) and Martens parameter (hardness: HM and indentation modulus: EIT). FL, FS and KIC were measured in a universal testing machine. The grain size was evaluated by scanning electron microscopy (SEM). Data was analyzed using one-way ANOVA followed by post hoc Scheffe, Kruskal–Wallis-, Mann–Whitney-U- and Pearson-test (p Results For translucency, negative correlations were found with results of facture load (R = −0.444, p Significance Despite of being based on the same raw material, tested zirconia materials significantly differed regarding optical, mechanical (except biaxial flexural strength and Martens hardness) and structural properties. Materials with highest optical properties were those with lowest mechanical properties (CER, COP).

To investigate two-body wear (2BW) and fracture load (FL) of monolithic ceramics after different surface pretreatments. Zirconia (MOZ), lithium-disilicate (LIT), and leucite-reinforced (LEU) specimens (n = 60/group) were manufactured with CAD/CAM-technology and underwent (n = 15/subgroup): 1) grinding + polishing (GrPo), 2) grinding + glazing (GrGz), 3) grinding (Gr), or 4) glazing (Gz). Scanning electron microscope (n = 3/subgroup) and 3D measurements of the ceramic crowns and antagonists (N = 180) were performed to determine 2BW before and after 120,000/1,200,000 masticatory cycles. FL was examined for all specimens (N = 180). Data were analyzed using Kolmogorov-Smirnov, one-way ANOVA, Scheffe post hoc, Kruskal-Wallis, Mann-Whitney-U, and Wilcoxon (p

Clinical RelevanceAs temporary materials are often used in prosthetic dentistry, there is need to investigate their behavior in the oral environment. Parameters such as surface roughness and surface free energy correlate to the level of plaque adhesion, which can impact gingival health.SUMMARYObjective:To test computer-aided design/computer-aided manufacturing (CAD/CAM)-fabricated and conventionally processed polymer-based temporary materials in terms of radiopacity (RO), surface free energy (SFE), surface roughness (SR), and plaque accumulation (PA).Methods and Materials:Six temporary materials (n=10/n=10) were tested, including three CAD/CAM-fabricated (CC) materials—Art Bloc Temp (CC-ABT), Telio CAD (CC-TC), and VITA CAD Temp (CC-VCT)—and three conventionally processed (cp) materials: Integrity Multi Cure (cp-IMC), Luxatemp Automix Plus (cp-LAP), and Protemp 4 (cp-PT4). Zirconia acted as the control group (CG, n=10). RO was evaluated according to DIN EN ISO 13116. SFE was investigated using contact angle measurements. SR was measured using a profilometer. The PA tests were performed using three microorganisms: Streptococcus mutans, Actinomyces naeslundii, and Veillonella parvula. Data were analyzed using Kolmogorov-Smirnov, Kruskal-Wallis, Mann-Whitney U-, Dunn-Bonferroni, Wilcoxon, Levene, and Pearson tests and one-way analysis of variance with post hoc Scheffé test (α=0.05).Results:No radiopacity was observed for any CC material or cp-PT4. CG showed the highest RO, while no differences between cp-IMC and cp-LAP were found. CG showed lower SFE compared to all polymer temporary materials, except in the case of CC-TC. cp-LAP and cp-IMC presented higher SFE than did CC-TC and CG. CC-ABT presented lower initial SR values compared to cp-PT4 and cp-LAP. For cp-LAP, a higher initial SR was measured than for all CAD/CAM materials and cp-IMC. All specimens showed a certain amount of PA after the incubation period. A naeslundii and V parvula resulted in comparable PA values, whereas the values for S mutans were lower by one log level. CAD/CAM materials showed superior results for SR, SFE, and PA, whereas all materials lacked RO.

For several years, there has been a clear trend in the dental market towards monolithic tooth-colored restorations. In this context, further developments, particularly in the field of zirconia ceramics, have led to considerable improvement in the materials' optical properties. Modern zirconia materials can be divided into several cohorts, differing from each other with respect to their optical and mechanical properties. The knowledge about indications and limitations of each zirconia cohort is essential for a correct clinical application. Clinical long-term experience for the zirconia of the newest generations is still scarce and only in-vitro data are available. Despite all advancements, clinical long-term success remains closely linked to the specific indications, preparation, material selection, knowledge, and experience of the dental practitioner and dental technician, as well as an adequate luting mode and occlusal concept. Due to the high innovation rate within materials and CAD/CAM technology in general, clinicians and dental technicians need to be well informed in order to be able to work successfully with the various options.

Statement of problem Veneering composite resins (VCRs) are often used to veneer frameworks, but knowledge of mechanical, surface, and discoloring properties is scarce. Purpose The purpose of this in vitro study was to evaluate the impact of thermocycling on flexural strength (FS) and the influence of different staining media on the discoloration (ΔE) and surface free energy (SFE) of VCRs. Material and methods The following VCRs were tested: Ceramage, dialog Vario, Gradia Plus, in:joy, Signum composite, and SR Nexco. FS was tested with enamel and dentin pastes (except SR Nexco: only enamel paste), whereas ΔE and SFE were analyzed for enamel pastes. ΔE was determined by using a spectrophotometer, and SFE was evaluated with contact angle measurements. For FS, rod-shaped specimens (N=660, n=10/subgroup; 25×2×2 mm) were fabricated, thermocycled for 220, 1500, 10 000, 20 000, and 40 000 cycles (5 °C/55 °C). and tested immediately after fabrication (initial) and after aging. For ΔE and SFE, disc-shaped specimens (N=300, n=10/subgroup; 15x15x1.4 mm) were fabricated and stored for 14 days in coffee, red wine, carrot juice, beetroot juice, or curry solution. ΔE and SFE were measured initially after polishing, after discoloration, and after repolishing. Data were analyzed using univariate analysis, 1-way ANOVA followed by the Scheffe post hoc test, Kolmogorov-Smirnov test, Kruskal-Wallis test, Mann-Whitney U test, and Wilcoxon test (α=.05). Results Ceramage had the highest FS, followed by dialog Vario and SR Nexco. Gradia Plus, and in:joy had the lowest FS, followed by Signum composite. FS was reduced by increasing of thermocycles. The highest ΔE was measured for curry and the lowest for carrot juice and red wine, followed by beetroot juice and coffee. The highest ΔE between the initial polished specimens and repolished specimens were observed for Ceramage. The remaining VCRs showed differences in ΔE between 0.95 (Signum composite) and 1.30 (SR Nexco). The SFE of the VCRs was similar. After storage in discoloring media, all VCRs had higher SFE than directly after polishing (initial). Repolishing decreased the SFE values compared with those of specimens measured after storage. Conclusions FS, ΔE, and SFE differed between the VCRs tested. Discoloration of the VCRs depended on the food and beverage and could be corrected to a clinically acceptable range by repolishing.

SUMMARY Objectives: To evaluate and compare the fracture toughness of dental CAD/CAM materials of different material classes intended for in-office milling (glass ceramics, hybrid, resin composites) and the influence of aging on this property. Methods and Materials: The fracture toughness (critical intensity factor, KIc) values of 9 CAD/CAM restorative materials (Ambarino High-Class, Brilliant Crios, Cerasmart, exp. CAD/CAM composite, Katana Avencia, Lava Ultimate, VITA Enamic, IPS Empress CAD, and IPS e.max CAD) were determined using the SEVNB method in a four-point bending setup. Twenty bending bars of each material with a 4 × 3 cross and a minimum length of 12 mm were cut out of CAD/CAM milling blocks. Notching was done starting with a pre-cut and consecutive polishing and v-shaping with a razor blade, resulting in a final depth of v-shaped notches of between 0.8 and 1.2 mm. Half of the specimens were selected for initial fracture toughness measurements. The others were thermocycled in distilled water for 30,000× (5/55°C; 30-second dwell time) before testing. Specimen fracture surfaces were analyzed using confocal laser scanning microscopy. Results: All specimens for each material fractured into two fragments and showed the typical compression curl and brittle failure markings. Comparing initial KIc values, lithium disilicate ceramic IPS e.max CAD showed significantly the highest and leucite-reinforced ceramic IPS Empress CAD significantly the lowest KIc values (p0.999-0.060). After thermal cycling, the highest KIc values were measured for lithium disilicate ceramic IPS e.max CAD, followed by resin composite materials Ambarino High-Class (p Conclusions: The materials tested show differences in fracture toughness typical for the class they belong to. With one exception (Ambarino High-Class), thermocycling affected the fracture toughness of materials with a resin component negatively, whereas the leucite and lithium disilicate ceramic showed stability.

Background The aim of this study was to investigate the effects of storage medium and aging duration on Martens hardness (HM) and indentation modulus (EIT) of self-adhesive resin-based cements (SARCs). Methods A total of 416 discs were fabricated from 8 SARCs (n = 52 per SARC): (i) BeautyCem (BEA), (ii) Bifix SE (BIF), (iii) Clearfil SA Cement Automix (CLE), (iv) RelyX Unicem2 Automix (RXU), (v) SeT (SET), (vi) SmartCem 2 (SMC), (vii) SoloCem (SOC) and (viii) SpeedCEM (SPC). The specimens were ground and stored in (a) physiological saliva, (b) artificial saliva, (c) sodium chloride and (d) distilled water, at 37°C for 1, 7, 14, 28, 90 and 180 days. Non-aged specimens (3 hours after photo-initiation) of each SARC acted as control groups. HM and EIT were assessed using a universal hardness testing machine. Data were analyzed using Kolmogorov-Smirnov and Kruskal-Wallis tests and paired t-test, and 3-, 2- and 1-way ANOVA with post hoc Scheffé test (pResults SARC materials exerted the highest influence on HM and EIT values (pP²] = 0.753 and 0.433, respectively), closely followed by aging duration (pP² = 0.516 and 0.255) and storage medium (pP² = 0.043 and 0.033). The interaction effect of the combinations of the 3 independent parameters was also significant (pP² = 0.163 and 0.133). The lowest initial HM and EIT was presented by CLE, followed by SET and SPC; highest HM was for BIF, followed by RXU and SMC. SET gave a greater HM and EIT percentage decrease than SOC, SPC, BEA, SMC, RXU or CLE. Conclusions Aging duration is a major factor affecting the micromechanical properties of SARCs, while storage medium was shown to have a significant but minor role.

Purpose To determine the effect of different individual, laboratory and professional cleaning methods on the surface-roughness (SR) and surface free energy (SFE) of polyetheretherketone (PEEK), PMMA-based (PMMA) and composite (COMP) materials. Methods 330 specimens of PEEK, PMMA and COMP (N = 990) were prepared and divided into the following cleaning protocols (n = 30/group): (i) individual prophylaxis using (ST) soft, (MT) medium-hard and (SOT) sonic toothbrushes, (ii) in-lab cleaning protocols consisting of (SY) Sympro cleaning system, (SS) SunSparkle, (UB) ultrasonic bath and (AP) Al2O3-powder device and (iii) professional prophylaxis applying (PS) Perio Soft-Scaler, (SO) Sonicsys, (AFC) Air Flow Comfort, and (AFP) Air Flow Plus. After each protocol SR (profilometer), SFE (contact angle devise) and surface topography (SEM) were measured. Data were analyzed using multivariate analysis, Kruskal-Wallis-H- and Mann-Whitney- U-test (pResults No impact of material on SR was observed (p = 0.443). Cleaning using conventional air-abrasion and powders (AP), followed by AFC produced higher SR values than the remaining methods (p2 = 0.246), closely followed by the polymer material (p2 = 0.136). PMMA and PEEK presented after cleaning lower SFE than COMP. PS, UB and SO showed lower SFE than specimens cleaned using SS, ST and SY. Cleaning using SY led to the highest SFE. Conclusions With regard to SR, all methods – with exception of conventional air-abrasion – can be recommended to clean PEEK. According to the SFE, PEEK may be an acceptable material providing even lower plaque accumulation rates than COMP. The field for more research is now open for scrutiny.

To assess the discoloration and stain removal potential of different cleaning methods relevant to individual/professional prophylaxis and laboratory cleaning on polyetheretherketone (PEEK), poly(methyl methacrylate) (PMMA)-based, and composite (COMP) materials after storage in different media for 7 days. One thousand three hundred twenty specimens of PEEK, PMMA, and COMP (N = 440 of each group) were prepared and stored in four different media for 7 days to cause stain. Samples were divided into three cleaning groups (n = 10): (i) individual prophylaxis, (ii) laboratory protocols, and (iii) professional prophylaxis. Color was determined by a portable spectrophotometer and calculated between different time points (∆E). The data was statistically evaluated using univariate analyses, Kruskal–Wallis H and Mann–Whitney U tests (p

Objective To investigate the impact of storage up to one year on the micro-mechanical properties of dental bioactive restoratives (R) used for bulk-application and their intermediate layer (IL) to dentin (D). Methods One giomer bulk-fill resin composite (RBC) and one glass-ionomer cement (GIC) were applied in 5-mm deep Class I cavities, which were prepared in 50 sound human molars. Specimens were stored in distilled water at 37 °C for 24 h, one week, one month, three months and one year. The variation in micro-mechanical properties (indentation modulus (Y HU ) and Vickers hardness (HV)) were determined in 100-μm steps in line-profiles located parallel to the tooth axis, starting 0.1 mm from the filling surface, through the IL in between R and D, and ending 300 μm in D. Results HV and Y HU were influenced by the material (p η 2 P = 0.011 and η 2 P = 0.395), immersion duration ( η 2 P = 0.081, η 2 P = 0.081) and depth ( η 2 P = 0.050, η 2 P = 0.091). The micro-mechanical properties progressively increased with immersion time in both restoratives, with a comparable time-dependency pattern, but to a different extent. IL showed weaker mechanical properties compared to more superficial cavity areas, which were maintained in RBC and even enhanced in GIC during storage. After one year of storage HV ranked in the following sequence: GIC: D: 61.4 ± 7.25-N/mm 2 , IL: 86.0 ± 23.63-N/mm 2 , R: 112.3 ± 30.36-N/mm 2 and RBC: D: 67.2 ± 11.55-N/mm 2 , IL: 76.7 ± 18.88-N/mm 2 , R: 94.1 ± 12.28-N/mm 2 . Conclusion No degradation with aging was identified in the giomer restorative. The gradual ascending transition in micro-mechanical properties from D through R identified in both restoratives might have a positive effect on the bond quality. Clinical significance Giomers represent a new category of restoratives with promising clinical behavior and good mechanical stability up to one year of aging under simulated clinical conditions.

Because of their industrially standardized process of manufacturing, CAD/CAM resin composites show a high degree of conversion, making a reliable bond difficult to achieve. The purpose of this experiment was to investigate the tensile bond strength (TBS) of luting composite to CAD/CAM resin composite materials as influenced by air abrasion and pretreatment strategies. The treatment factors of the present study were (1) brand of the CAD/CAM resin composite (Brilliant Crios [Coltene/Whaledent], Cerasmart [GC Europe], Shofu Block HC [Shofu], and Lava Ultimate [3M]); (2) air abrasion vs. no air abrasion; and (3) pretreatment using a silane primer (Clearfil Ceramic Primer, Kuraray) vs. a resin primer (One Coat 7 Universal, Coltene/Whaledent). Subsequently, luting composite (DuoCem, Coltene/Whaledent) was polymerized onto the substrate surface using a mold. For each combination of the levels of the three treatment factors (4 (materials) × 2 (air abrasion vs. no air abrasion; resin) × 2 (primer vs. silane primer)), n = 15, specimens were prepared. After 24 h of water storage at 37 °C and 5000 thermo-cycles (5/55 °C), TBS was measured and failure types were examined. The resulting data was analyzed using Kaplan–Meier estimates of the cumulative failure distribution function with Breslow–Gehan tests and non-parametric ANOVA (Kruskal–Wallis test) followed by the multiple pairwise Mann–Whitney U test with α-error adjustment using the Benjamini–Hochberg procedure and chi-square test (p

Statement of problem The lengthy sintering time of zirconia is costly and limits applications. The consequences of shortening the sintering time are mainly unknown. Purpose The purpose of this in vitro study was to test and compare 2 high-speed sintering protocols and 1 conventional sintering protocol on the translucency, phase content, grain sizes, and flexural strength of 3 zirconia materials. Material and methods In total, 450 specimens of 3 zirconia materials—two were 3 mol% yttria-stabilized tetragonal zirconia polycrystals (3Y-TZPs), Ceramill ZI and Zolid (ZD), and a 4 mol% yttria-stabilized tetragonal zirconia polycrystal (4Y-TZP), Zolid HT+ (n=150)—and 5 thicknesses (1.0, 1.5, 2.0, 2.5, and 3.0 mm; n=30) were sintered according to 2 high-speed sintering protocols (final temperature 1570 °C and 1590 °C; n=10) and a reference sintering protocol (1450 °C; n=10). After measuring the monoclinic phase content with Raman spectrometry (n=3), the specimens were polished, and translucency was determined. The biaxial flexural strength of specimens with a thickness of 1.0 mm and 1.5 mm was tested (n=20). Statistical evaluation included 1-way ANOVA, the Kolmogorov-Smirnov, Kruskal-Wallis, Mann-Whitney-U, and Spearman-Rho tests and the Bonferroni correction (α=.0011). Results For ZI, the sintering protocols did not affect the translucency or biaxial flexural strength. ZD and HT+ showed significantly lower translucency for high-speed sintering protocols (P≤.001), but the biaxial flexural strength remained the same after the high-speed sintering protocol at 1590 °C. Grain sizes increased with increasing final sintering temperature for ZI and HT+, whereas translucency generally decreased with increasing material thickness. No monoclinic phase was detected in any group. Conclusions The flexural strength was maintained with high-speed sintering but led to a decrease in translucency for ZD and HT+.

The purpose of this topic review is to give a general overview of gingival retraction agents used during prosthodontic treatment, and the possible difficulties connected to them that may be faced by the dentist. Hemostatic agents are important for successful gingival retraction and in achieving hemostasis. However, these agents may show numerous negative effects on the prosthodontic treatment and oral tissues of which the practicing dentist must be aware, and which will be elucidated in this review. PubMed and Google Scholar databases were searched for publications up to and including 2017. The following key words were used in different combinations: "hemostatic agent," "astringent," "astringency," "epinephrine," "ferric sulfate," "aluminum chloride," "hemorrhage control," "soft tissue," "hard dental tissue," "self-etch adhesive," "total-etch adhesive," "bond strength," "impression," "gypsum," "plaster cast," and "dental cast." In the last three decades the hemostatic agents used by practicing dentists have changed from epinephrine towards astringents, with AlCl3 and Fe2(SO4)3 now the most popular. All of the currently known hemostatic agents cause some local, temporary gingival tissue damage, but only epinephrine is known to elicit negative systemic effects. Studies concerning the influence of hemostatic agents on impression materials show highly contradictory results regarding the possible polymerization-inhibiting properties of hemostatic agents, probably due to the lack of standardization of methodology. Hemostatic agents seem to alter the dentinal surface properties making it more resistant to acid etching. Therefore the relatively low acidity of self-etch adhesives when compared to total-etch systems may not be strong enough to sufficiently etch a more resistant dentinal surface, and consequently may result in lower adhesive bond strengths.

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.

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

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.