Effect of hot-etching treatment on shear bond strength of zirconia to resin cement

ABSTRACT

The purpose of this study was to evaluate the effect of hot-etching surface treatment on the shear bond strength between zirconia ceramics and resin cement. Ceramic cylinders were divided randomly into 10 groups (n?=?10) according to different surface treatments (blank control; airborne particle abrasion; hot-etching for 10?min; hot-etching for 30?min; hot-etching for 60?min) and whether or not performed thermal cycling fatigue test. Flat enamel surfaces, were prepared from human permanent incisors and were bonded to the zirconia discs. All specimens were subjected to shear bond strength test by a universal testing machine. All data were statistically analysed using one-way analysis of variance and multiple comparison least significant difference tests (α?=?0.05). Hot-etching for 60?min treatment produced higher bond strengths than the other treatment. Surface treatment of zirconia with a hot-etching solution might enhance surface roughness and bond strength between zirconia and resin cement.     

The effect of different surface pretreatments on the bond strength of veneering resin to polyetheretherketone

The aim of this study was to investigate the effect of different surface pretreatment methods on the bond strength of veneering resin to polyetheretherketone (PEEK) based aesthetic frameworks. Five hundred and forty PEEK disks were fabricated and divided into 6 pretreatment groups (n = 90); (C) untreated control group, (B) airborne-particle abrasion, (S) silica coating, (L) etching with Er:YAG (erbium-doped yttrium aluminium garnet) laser, (LB) etching with Er:YAG laser and airborne-particle abrasion and (LS) etching with Er:YAG laser and silica coating. After topographical surface examinations, specimens were conditioned with adhesive and veneering resin was polymerized onto the PEEK specimens. Twenty-four hours after veneering, specimens were subjected to thermal aging. Afterwards, shear bond strength (SBS) tests were performed and the obtained data were analyzed with one-way ANOVA and Tukey test at a significance level of α = .05. Group B (1.58 ± 0.15 μm), Group L (1.79 ± 0.29 μm), Group LB (2.20 ± 0.23 μm) and Group LS (2.31 ± 0.52 μm) demonstrated significantly higher surface roughness (SR) values compared to Group C (1.03 ± 0.11 μm). Group B (10.97 ± 2.88 MPa), Group S (12.07 ± 2.82 MPa), Group LB (12.09 ± 2.08 MPa) and Group LS (13.14 ± 1.45 MPa) demonstrated significantly higher SBS values compared to Group C (6.35 ± 1.21 MPa). Airborne-particle abrasion, silica coating or their combined use with Er:YAG laser system establish durable bond between PEEK and resin; however, only Er:YAG laser treatment has no positive effect on resin-PEEK bond.     

Shear bond strengths of six different porcelain laminate veneer materials cemented to enamel with two different MDP-containing resin cements

Purpose: To compare the shear bond strengths of six different porcelain laminate veneer (PLV) materials cemented to enamel with two different MDP-containing resin cements. Materials and methods: Totally 120 disc specimens were fabricated with In-Ceram alumina (ICA), Turkom-Cera^TM (TCR), IPS Empress (IPS), IPS Empress-II (IPS2), Finesse (FNS), and Ceramco-3 (CER) ceramic systems (n = 20). Sixty specimens were cemented with self-adhesive resin cement (Clearfil SA), and 60 specimens were cemented with self-etch resin cement (Panavia F2.0) to enamel. Thus, 120 PLV–enamel specimens were assigned to 12 experimental groups (ICA/Pv, ICA/Cf, TCR/Pv, TCR/Cf, IPS/Pv, IPS/Cf, IPS2/Pv, IPS2/Cf, CER/Pv, CER/Cf). Shear force was applied on PLV–enamel interfaces until failure. Obtained data were statistically analyzed with ANOVA and t-tests. Results: Obtained shear bond strength values (SBSV) ranged as follows, respectively; TCR/Cf (7.70 MPa), FNS/Cf (7.57 MPa), TCR/Pv (6.91 MPa), ICA/Pv (5.05 MPa), CER/Pv (4.75 MPa), IPS2/Cf (4.66 MPa), FNS/Pv (4.43 MPa), IPS2/Pv (3.97 MPa), CER/Cf (3.82 MPa), IPS/Pv (3.62 MPa), ICA/Cf (3.59 MPa), IPS/Cf (3.11 MPa). Highest SBSV were obtained in TCR groups (7.70 MPa for TCR/Cf and 6.91 MPa for TCR/Pv) and lowest SBSV were obtained in IPS groups (3.11 MPa for IPS/Cf and 3.62 MPa for IPS/Pv) in both resin cements. No significant bond strength difference was found between two resin cements. Conclusions: TCR groups showed highest SBSV; lowest SBSV were obtained with both IPS PLVs. The resin cement type did not significantly affect the bond strength value of a ceramic type, except for the Finesse system.     

Bond strength of short-pulsed laser-irradiated zirconia to veneer ceramic

Objective: The aim was to evaluate the effect of 1064 nm Yb-doped fiber-based nanosecond pulsed laser on surface roughness and bond strength between veneer ceramic and zirconia. Material and methods: Zirconia discs were divided into three groups: sandblasted (SB), laser irradiated (YL), and control (n?=?12). YL group was treated with ytterbium laser with the setting of 85 W/25 kHz. Sandblasting was done using 50 μm Al₂O₃ particles from a distance of 10 mm for 20 s under 3.5 atm. No surface treatment was applied to the control group. The surface roughness values and SEM images of the groups were obtained. X-ray diffraction analysis was applied to a spare sample of each group to determine the monoclinic phase ratio. The samples were subjected to shear bond strength (SBS) test with a cross-head speed of 1 mm/min after being veneered. The fracture modes were evaluated. One-way analysis of variance and Tukey’s HSD tests were used for statistical analysis. Results: The YL group had higher surface roughness than the control (p?≤?0.0001) and the SB group (p?=?0.007) with a mean value of 2.90 μm. The SEM images of the groups supported this result, but formation of the microcracks was more intense for the YL group. The monoclinic phase ratio was highest for the SB group. However, the differences of SBS between SB and YL groups were not statistically significant. Mostly the combined failure of samples was observed. Conclusions: Ytterbium laser treatment increased the surface roughness of zirconia, but the SBS was not higher than sandblasting. Surface roughness results did not correlate with the SBS results.     

Effect of femtosecond laser beam angle and formed shape on surface roughness and shear bond strength between zirconia and resin cement

Achieving adhesion between resin cement and zirconia requires pretreatment of the surface. This in vitro study aimed to evaluate the effect of femtosecond laser beam angle and the shape of the formed surfaces, on the roughness and shear bond strength (SBS) of resin cement to zirconia ceramic. Seventy Y-TZP ceramic specimens were divided into seven groups (n = 10). A femtosecond laser irradiation was performed on the ceramic surface of three shapes (spiral (SP), square (SQ) and circular (CI) and at two angles (30 and 90°) to give SP-30, SQ-30 and CI-30 and SP-90, SQ-90 and CI-90, respectively. After treatment, the surface roughness of all specimens was evaluated using a profilometer. One specimen from each group was analysed using a scanning electron microscope. The bonded specimens were thermocycled 5000 times and then an SBS test was performed. Kruskal-Wallis and Mann-Whitney U tests were used to analyse surface roughness and SBS values. The control group had statistically lower surface roughness (R_a) values than the treated groups (p < 0.05). SP-30 and SQ-30 laser treated specimens showed higher R_a values than the other specimens. Statistically significant SBS values (p = 0.000) were observed between the groups. All laser treated samples showed greater SBS compared to the control group. SP-30, SQ-30 and SQ-90 groups showed the highest SBS values. Within the limitations of this experimental study, the highest mean values for R_a and SBS were achieved with SP and SQ surfaces using a 30° angle laser beam.     

Adhesive bond strength and compressive strength of a novel bulk fill composite with zirconia nano-hybrid filler

The aim of the study was to investigate the adhesive bond and compressive strength of novel bulk fill resin composite with zirconia (Zr) nano-hybrid filler. Sixty molars were mounted in acrylic resin with flat occlusal surface. Half of the specimen (n = 30) were bonded using total etch (TE) and the other half with self-etch (SE) technique. Specimens treated with SE (n = 30) and TE (n = 30) bonding protocol were divided into three groups, based on the type of bulk fill build-up materials (ZC–ZirconCore, MC–MulticCore Flow and LC–Luxacore Dual), resulting in six study groups [MC-TE, MC-SE, LC-TE, LC-SE, ZC-TE, ZC-SE]. Cylindrical (3 × 3 mm) build-ups were performed followed by shear bond strength testing (crosshead speed-1 mm/min). Ten specimens for each bulk fill build-up material (MC, LC and ZC) were prepared for compressive strength testing. All specimens were tested for maximum failure loads (crosshead speed?0.5 cm/min). Analysis of variance and paired t-test were performed to statistically analyze the data. TE technique showed significantly higher bond strength values as compared to SE technique (p < 0.001) for all three materials (MC, LC and ZC). Shear bond strength for MC [TE,17.88(2.00)-SE,9.43(0.98)] and LC [TE,18.91(2.57)-SE,6.35(1.12)] groups were significantly higher than ZC group [TE,13.99(1.09)-SE,4.61(0.84)]. Specimens in ZC group (266.73 ± 9.76) showed significantly higher compressive strength in comparison to MC (247.66 ± 9.72) (p = 0.004) and LC (249.87 ± 13.17) (p < 0.001) groups. Zirconia nano-hybrid filler resin bulk fill material has comparatively high compressive strength and low bond strength making them suitable for clinical applications in the posterior region with favorable conditions for adhesive bonding.     

Effects of surface treatments on the shear bond strength of luting cements to zirconia

Objective: The aim of this in vitro study was to evaluate the effect of surface treatments on the shear bond strength of resin cements to zirconia. Material and methods: Sintered zirconia specimens (n = 192) were divided into four different surface treatment groups: control (no treatment); airborne-particle abrasion; glaze layer and hydrofluoric acid (HF) application, and hot etching solution application. Then, each group was divided into four subgroups (n = 12), and three different resin cements were applied to the zirconia surfaces. The shear bond strength value of each specimen was measured after 5000 thermo cycles. The failure types were examined with a stereomicroscope and the effects of the surface treatments were evaluated with a scanning electron microscope. Results were analyzed using analysis of variance and Tukey’s post hoc tests (α = 0.05). Results: The surface treatment and resin cement type significantly affected the bond strength results (p < 0.05). For all resin cements, the airborne-particle abrasion treatment increased the shear bond strength values (p < 0.05). The glaze layer & HF application increased shear bond strength values for all groups, except the Single Bond Universal-RelyX Unicem Aplicap group (p < 0.05). The surface roughness values of airborne-particle abraded specimens were similar to comparable values for specimens from the control group and the hot etching solution group (p > 0.05). The glaze layer & HF application group produced the highest surface roughness values (p < 0.05). Conclusion: The results of this study recommend using the appropriate combination of surface treatment and adhesive/silane coupling agent to achieve durable zirconia-resin bonding.     

Effect of different surface treatments on the shear bond strength of resin cement to zirconia ceramic and metal alloy*

The bonding of resin cement to ceramic materials plays an important role in dentistry. The purpose of this study is to evaluate the effects of various surface treatments on the shear bond strength (SBS) of zirconia ceramic and metal alloy. A total of 60 specimens were prepared from Y-TZP ceramic and metal alloy. The specimens were divided into three subgroups (n = 10) that received different surface treatments for each material. An Er:YAG laser (ER), a femtosecond laser (FS), and air-borne particle abrasion (A) were employed as surface treatments. One specimen from each group was analyzed using a scanning electron microscope (SEM) at 500 x magnification after surface treatments. The self-adhesive resin cement was then bonded to the treated surfaces using a Teflon mold. The specimens were thermocycled for 5,000 cycles at 5–55 °C, and then the SBS test was performed. Kruskal–Wallis and Mann–Whitney U tests were used to determine the differences between the groups (p = 0.05), and failure modes were evaluated for each specimen. Statistical analyses revealed significant differences between the surface treatment methods. The mean SBS values of the air-borne particle-abraded groups were higher than those of the other groups. The femtosecond-irradiated groups of each material showed significantly higher SBS values than the Er:YAG-irradiated groups (p < 0.05). Within the limitations of this study, air-borne particle abrasion and the femtosecond laser were more effective than Er:YAG laser treatment.     

Shear bond strength tests of zirconia veneering ceramics after chipping repair

All ceramic systems are replacing the classical metal–ceramic crowns in dental practice. Zirconium dioxide (zirconia) core associated with veneering ceramic provides both good mechanical and aesthetic properties of prosthetic restorations. However, such zirconia crowns may be affected by defects of adaptation, too tight contacts in the proximal area and fissures of the ceramic veneer. The latter produces chipping; this requires a reattachment, therefore a second burning of the zirconia–ceramic interface. Such an additional procedure may affect the mechanical resistance of the ceramic veneer and the bond between the zirconia core and the ceramic veneer. The aim of this study was to evaluate the alterations of this shear bond strength (SB) between the zirconia core and the ceramic veneer, as produced by the first set of complete burning procedures and by the second correction burning of the dental restorations. Thirty-three zirconia discs were veneered with ceramic material and the SB was evaluated for each sample. Each ceramic cylinder detached from the zirconia was bonded on the core through a new layer of dentin and another burning procedure; the SB was tested again. The results of the two SB tests were compared; the statistical analysis concluded that there is an approximately 10% decrease of the resistance after the second burning. Also, the spread of the values for each test showed the high impact of the human factor on such dental restorations. In all the tests, the weakest area proved to be the interface between the zirconia core and the layered ceramics.     

The effect of MDP-based primer on shear bond strength of various cements to two different ceramic materials

The aim of this study was to determine the effect of 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-based primer on the shear bond strengths of thermally aged self-adhesive and conventional adhesive resin cements and zinc phosphate cement to zirconia and lithium disilicate substructures. Sixty zirconia (Z) and 60 lithium disilicate (L) disk specimens were cut from ceramic blocks. Each group was divided into six subgroups (n = 10). Half of the specimens of each ceramic group were treated with primer (P) and the other half was remained untreated. Three types of cement were applied: zinc phosphate cement [(ZPC) (Hoffmann Harmonic Shades)]; self-adhesive resin cement [(SAC) (RelyX U200)]; conventional adhesive resin cement [(CAC) (C&B)]. The specimens were subjected to thermal aging procedure for 1 week under 37 °C water bath. Shear bond strength (SBS) was determined using a universal testing machine at a crosshead speed of 1 mm/min. Data were analyzed with three-way (ANOVA). Pairwise comparisons and interactions between groups were analyzed by using Tukey’s simultaneous confidence intervals. There was no significant difference between the SBS values of SAC-Z (11,47 ± 0,47) and SAC-ZP (11,39 ± 0,42) (p > 0.05). However, the SBS values of SAC-L (12.34 ± 0,55) and SAC-LP (12,50 ± 0,49) were significantly higher than those of SAC-Z and SAC-ZP (p < 0.00). The use of primer significantly increased the SBS value of CAC-ZP (8,05 ± 0,55) when compared to the SBS value of CAC-Z (3,53 ± 0,41) (p < 0.00). Resin cement that contains methacrylate monomers with phosphoric ester functional groups exhibited reliable bond to zirconia. However, the use of an MDP-based primer may not further improve its bond strength.     

Bond strength of veneering porcelain to zirconia after different surface treatments

Aim: The aim of this study was to evaluate the effect of various surface treatments on the bond strength of veneering feldspathic porcelain to zirconia. Methods: Fifty yttria-stabilized tetragonal zirconia polycrystalline specimens were divided into five groups (n = 10) according to various surface treatments. The groups were as follows: Group 1: control group with liner application and no further surface treatment; Group 2: air-particle abrasion with 110 μm of alumina (Al₂O₃) particles; Group 3: grinding with a diamond disk; Group 4: Nd:YAG laser irradiation (the laser and the energy parameters were 10 Hz, and 2 W and 200 mJ, and the pulse duration (short pulse) range was up to 180 μs); Group 5: selective infiltration etching (SIE). After surface treatments, a liner application was performed for all surfaces according to the manufacturer’s instructions. Veneering porcelain was applied on zirconia surfaces using a Teflon mold. Shear bond strength was tested using a universal testing machine. The fractured surface morphologies were examined with scanning electron microscopy. The data were statistically analyzed using Mann–Whitney U and Kruskal–Wallis tests (α = .05). Results: The Megapascal values of the bonding groups were as follows: G1 = 8.62 ± 1.12, G2 = 13.87 ± 5.08, G3 = 12.31 ± 3.35, G4 = 17.32 ± 6.16, and G5 = 16.17 ± 4.55. Statistically significant differences were observed between the control group and the other groups (p < 0.05). Group 4 had the highest bond strength while G1 showed the lowest bond strength. No significant differences were found between the Nd:YAG, grinding, sandblasting, and SIE groups. Conclusion: Surface treatments had different effects on the shear bond strength of feldspathic porcelain to zirconia. Surface treatment techniques used in this study can be used on zirconia specimens prior to liner application to obtain an acceptable bond strength of veneering porcelain to zirconia. The effect of Nd:YAG laser irradiation and SIE techniques on bond strength of veneering ceramic to zirconia should be evaluated with further studies.     

Effectiveness of different surface cleaning methods on the shear bond strength of resin cement to contaminated zirconia: an in vitro study

The purpose of this in vitro study was to evaluate and compare the effectiveness of different surface cleaning methods on the shear bond strength (SBS) of zirconia ceramic surfaces. Seventy polished and cleaned zirconia disk specimens of 8 mm in diameter and 3.4 mm in thickness were immersed in fresh saliva. They were then pressed into a freshly mixed silicone disclosing medium. Six different cleaning methods were applied to the tested groups; they were airborne-particle abraded (AA), covered with a cleaning paste (Ivoclean®) (IV), etched with orthophosphoric acid (PA), immersed in alcohol (AL), rinsed with tap water only (WA), or cleaned with steam (SC). No surface cleaning was done after saliva immersion and silicone disclosing medium contamination to the control group (CC). The specimens were then bonded to an adhesive resin cement using polyethylene tubes. SBS was determined using a universal testing machine at a crosshead speed of 1 mm/min. The specimens were also examined with a scanning electron microscope and a stereomicroscope. Group AA yielded the highest SBS value (7.01 ± 1.4 MPa) among the groups, while Group WA had the lowest SBS value (3.03 ± 0.8 MPa). The SBS values of Group AA (7.01 ± 1.4 MPa) and IV (6.2 ± 1.7 MPa) were also significantly higher than those of the remaining four groups (p < 0.05). Within the limitations of this in vitro study, it was concluded that among the various cleaning methods tested, airborne-particle abrasion and Ivoclean® paste were effective in cleaning the zirconia surface.     

Evaluation of different desensitizing agents effect on shear bond strength of adhesive resin cement to dentin

Desensitizing agents can inhibit the bonding strength between dentin and adhesive resin cement. This study evaluated the effects of different desensitizing agents on the shear bond strength of adhesive resin cement to dentin. Sixty freshly extracted and caries free teeth were classified into five experimental groups, randomly (n?=?12). Each group was treated with a different desensitizing agent (Teethmate, Shield Force Plus, Admira Protect and Ultra-Ez) respectively, except for an untreated control group. After desensitizing agents and adhesive resin cement were applied to each dentin surface, all specimens were stored in incubator at 37?°C for 24?h. The shear bond strength was tested with a Universal testing machine at a 0.5?mm/min crosshead speed. Data were analysed by using a statistical software (SPSS 22). The results of the measurements were analysed by Kruskal Wallis test with Bonferroni correction and multiple comparisons were made by Wilcoxon test (p???.01). Specimens were examined by a scanning electron microscope, additionally. The Shield Force Plus showed significantly the highest shear bond strength compared with other groups (p?<?.01). Ultra-Ez showed the lowest shear bond strength (p?>?.01). There was no significant difference among Teethmate and Admira Protect groups (p?>?.01). Desensitizing agents containing resin monomers increased the bonding strength, however desensitizers containing calcium phosphate, potassium nitrate and fluoride did not effect the bonding strength of resin cement to dentin.     

Correlation among crystalline morphology of PEEK,interface bond strength,and in‐plane mechanical properties of carbon/PEEK composites

The effect of the cooling rate on in‐plane and interlaminar properties of carbon fiber/semicrystalline PEEK matrix composites was studied. Strengths and moduli were measured in tension, flexure, and interlaminar shear, all of which were shown to correlate, to different degrees, with the fiber–matrix interface adhesion and the bulk matrix properties. The in‐plane and interlaminar properties, in general, increased with a decreasing cooling rate, which was attributed to changes in the failure mechanism from adhesive failure involving fiber–matrix interface debonding at high cooling rates to matrix‐dominant cohesive failure at low cooling rates. The present study demonstrates that the mechanical properties of semicrystalline thermoplastic composites can be tailored for desired applications by controlling the processing conditions, especially the cooling rate. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1155–1167, 2002; DOI 10.1002/app.10406     

An investigation of atomic force microscopy,surface topography and adhesion of luting cements to zirconia: effect of silica coating,zirconia primer and laser

This study evaluated the effect various surface conditioning methods on the surface topography and adhesion of luting cements to zirconia. Zirconia blocks (N?=?25) were randomly assigned to five groups according to the surface conditioning methods: (a) No conditioning, control (CON), (b) tribochemical silica coating (TSC), (c) MDP-based zirconia primer (ZRP), (d) coating with nano aluminum nitride (ALN) (e) etching with Er: YAG laser (LAS). The conditioned zirconia blocks were further divided into five subgroups to receive the luting cements: (a) MDP-based resin cement (Panavia F2.0) (PAN), (b) 4-META-based cement (Super Bond) (SUB), (c) UDMA-based (GCem) (GCE), (d) bis-GMA based (Bifix QM) (BIF) and (e) polycarboxylate cement (Poly-F) (POL). Cements were applied in polyethylene moulds (diameter: 3?mm; height: 2?mm). The bonded specimens were first thermocycled for 5500 cycles (5–55?°C) and then adhesive interface was loaded under shear (0.5?mm/min). The data (MPa) were analyzed using 2-way ANOVA, Tukey’s and Bonneferroni tests (alpha?=?0.05). Regardless of the cement type, TSC resulted in significantly higher bond strength (p???0.05) (13.3?±?4.35–25.3?±?6.3) compared to other conditioning methods (2.96?±?1.5–5.4?±?5.47). Regardless of the surface conditioning method, no significant difference was found between MDP, 4-META and UDMA based cements (p?>?0.05) being significantly higher than those of bis-GMA and polycarboxylate cements (p???0.05). Failure types were frequently adhesive in all groups. Tribochemical silica coating provided superior bond results compared to other conditioning methods tested on zirconia especially in conjunction with UDMA- and 4-META-based resin cements.     

Shear bond strength to enamel and failure type of different periodontal splints: an in vivo and in vitro study

The goal of this study was to evaluate the shear bond strength (SBS) and failure mode of four different splint materials [Polyethylene FRC Ribbond Thm (RB), Polyethylene FRC Construct (Kerr), Multifilament Fishing Line (MFL), and Non Fiber Reinforced Composite (control)]. Thirty-seven subjects were randomly divided into four splint methods. After splinting procedures, the subjects were recalled 12 months later. One hundred and sixty human mandibular incisors (for extracoronal and intracoronal splinting) and 40 sheep mandibles (only extracoronal splinting) were used for the in vitro part. The specimens were subjected to SBS at their incisoproximal contact, and debonding forces were measured with a universal testing machine (1 mm/min crosshead speed). Failure sites were examined under a stereomicroscope (×40 magnification). The SBS data were assessed via analysis of variance (ANOVA) and Tukey’s tests. The survival rate was significantly affected by the splint type (RB:95.3%, Kerr:91.6%, MFL:93.5%, Control:52.5%). No statistically significant differences were found between RB, Kerr, and MFL (p > 0.05) at all in vitro parts. Intracoronal splinting showed lower SBS values than extracoronal (p < 0.05). Lower SBS values were obtained in sheep teeth than human teeth (p < 0.05). Significantly different fracture patterns were noted between groups (p < 0.05). Only resin composite application seems to be inadequate for periodontal splinting. MFL splints are also economic and quite resistant, and they might be used as an alternative to fiber-reinforced composites.     

Friction welding joint analysis of dissimilar nanocomposites: PEEK/aluminum to PEEK/titanium

Welding of dissimilar materials is extremely challenging to the researchers. In present work, for the first time, poly(ether ether ketone) (PEEK) based aluminum (Al), titanium (Ti) reinforced nanocomposites with varying reinforcements of 10, 20, 30, and 40 vol% were developed using powder metallurgy technology. Additionally, for the first time, the two dissimilar nanocomposites of PEEK/Al and PEEK/Ti were successfully welded by friction welding (FW) process to produce FW PEEK/Al-PEEK/Ti nanocomposites with equal metallic reinforcements (viz., 10–40 vol% Ti or Al). The nanocomposites were characterized precisely and correlated by physical, microstructural, structural, thermal, and micromechanical tests. Crystallinity being a factor of melting temperature affects significantly the micromechanical characteristics influenced by reinforced particle-concentrations. The FW PEEK/30Al-PEEK/30Ti was found as best material since it showed highest nanohardness (0.652 GPa) and elastic modulus (15.902 GPa) in FW Joint at 40 mN compared to other FW nanocomposites. At the FW joint section, it was discovered that the reinforced particles were being transferred through an interdiffusion mechanism. Mobility of the nanoparticles was influenced by the concentration of the reinforced particles, which further modified the matrix's crystallization behavior and consequently influenced the FW nanocomposites' micromechanical properties. Therefore, the present work has suggested a feasible route for applying thermoplastic nanocomposites in the biomedical and aerospace industries.     

Effect of different surface shapes formed by femtosecond laser on zirconia-resin cement shear bond strength

Objective: The purpose of this study was to evaluate the effect of different surface shapes formed by femtosecond (FS) laser on zirconia (Y-TZP)-resin cement shear bond strength (SBS). Background data: All ceramic restoration is used as an alternative to metal-ceramic restorations, due to its better aesthetics, strength, and toughness properties. However, bond strength of restoration to tooth and other materials is effective to long term success of the restoration, and to achieve it surface treatment is required on ceramic surface. Materials and methods: Forty square-shaped zirconia samples were prepared and assigned to four groups of 10. The details of the groups are as follows: Group A, square-shaped recessed surface; Group B, square-shaped projection surface; Group C, circular-shaped recessed surface; Group D, circular-shaped projection surface. The SBSs values were performed with a universal testing machine at a crosshead speed of 1 mm/min. The data were analyzed statistically using analysis of variance (ANOVA) and Tukey HSD multiple comparisons tests. Results: The one-way ANOVA results on SBSs of the zirconia material bonded with resin cement revealed significant differences among the groups (p < 0.05). The Tukey HSD test results revealed that Group B and D had significantly higher SBS values than other groups (p < 0.05), but there were no significant differences between each other (p > 0.05). Additionally, Group A and C had significantly lower values than other groups (p < 0.05). Conclusions: Different surface shapes formed by FS laser provided a significant increase in SBSs. The SBS values of projection surfaces of circular and square-shapes are greater than that of recessed surfaces of circular and square-shapes.     

Evaluation of a new test method to determine the failure mode and macro-shear bond strength of dental materials to metals

Objective: To compare the macro mean shear bond strength (SBS) and failure mode of three cements to two types of metal using mould-enclosed and non-enclosed cement specimens. Methods: Titanium and base metal cobalt-based substrates were finished with 50 μm aluminium oxide. Two resin-modified glass-ionomers (Riva Luting Plus, Fuji Plus) and one resin cement (RelyX Unicem) were prepared as per manufacturers’ instructions. Metal mould-enclosed and non-enclosed cement specimens with a bonding area diameter of 3.5?mm were prepared and stressed to failure using a 2 mm blunt edge shear knife at a cross-head speed of 1?mm/min to determine mean SBS. The shear knife was placed against the surface of the substrate. Failure analysis of the failed interface was performed with a stereo microscope at 40× magnification. Results: Two-way Analysis of Variance demonstrated a significant difference in mean SBS between materials (p?=?0.004) and cement (p?=?0.001). There was also a significant interaction between method and cement on SBS, F(2,?170)?=?7.209, p?=?0.003. Post hoc Tukey tests demonstrated no significant difference for either resinmodified glass-ionomer cements (RMGIC) (p?=?0.864, p?=?0.620) when comparing non-enclosed and mould-enclosed test methods bonded to titanium. There was however a significant difference (p?<?0.001) between the mean SBS obtained for the resin cement when comparing the non-enclosed and mould-enclosed test methods. For base metal, the RMGIC’s SBS was higher than resin cement but no difference was observed between one of RMGIC’s and the resin cement non-enclosed mean SBS. Although not the case for RMGIC’s bonded to titanium or one RMGIC bonded to non-precious cobalt-based metal, when comparing the test method on each cement, RMGIC and the resin cement showed significant differences between non- and mould-enclosed specimens mean SBS. In the non-enclosed specimen tests, 71% of all specimens tested exhibited adhesive failure, which was statistically different (p?<?0.001) to 91% for the mould-enclosed specimens. Failure mode was not always statistically different within groups, however non-enclosed specimens showed higher frequencies of mixed failures. Conclusion: Within the limits of this study, significant differences were found in comparing the mean SBS between mould-enclosed and non-enclosed specimens. A significant difference was found in failure mode between mould-enclosed and non-mould enclosed specimens. Mould-enclosed specimens bonded to metal exhibited a higher frequency of adhesive failure than non-mould enclosed specimens. Relevance: Mould-enclosed specimens used in place of non-enclosed specimens can be used in SBS testing to give a more valid result when bonding to metal.     

Influence of surface energy parameters of dental self-adhesive resin cements on bond strength to dentin

The purpose of this study was to determine the surface energy parameters of dental self-adhesive resin cements (SRCs) and to measure their bond strength to dentin. Six dental SRCs (RelyX Unicem Clicker, RU; Maxcem Elite, ME; BisCem, BC; Clearfil SA Luting, SA; Multilink Speed, MS; seT PP, SP) and one resin-modified glass ionomer cement (RelyX Luting 2, RL; control) were tested. Smear layer-covered bovine dentin was used as bonding substrate. Using the dynamic sessile drop method, surface energy, surface energy components, degree of hydrophobicity/hydrophilicity (expressed as ΔG _sws using thermodynamic notation), and apparent surface energies for each material were calculated. The luting cements were bonded to the dentin and stored in water at 37?°C for 24?h prior to shear bond strength test (n?=?10). Pearson correlation analysis was applied to detect possible correlations between surface energy parameters and measured shear bond strength (α?=?0.05). RU, SA, and MS produced negative ΔG _sws values (hydrophobic), whereas ME, BC, SP, and RL yielded positive ones (hydrophilic). RU had the highest value among all six SRCs tested, the value for MS being statistically equivalent (p?=?0.785). The base component, ΔG _sws, and surface energy determined with water showed significant negative linear correlations with dentin bond strength (r/p?=??0.801/0.030, ?0.900/0.006, and ?0.892/0.007, respectively). These results suggest that bonding to smear layer-covered bovine dentin was governed by the base component and the hydrophobicity/hydrophilicity of the SRCs.