Effects of Different Denture Cleansers on the Tensile Bond Strength of Denture Liners

The effect of two denture cleansers (Polident® and Protefix®) on the tensile bond strength between four soft liner materials (Molloplast B®, Permaflex®, Sofreliner Tough Medium®, and GC Reline Soft®) and a conventional denture base resin was investigated. For each of the liner materials 35 test specimens were prepared according to test the requirements and assigned into seven groups (n = 5). Before tensile testing, five of the liner specimens were kept in water or soaked in two cleansing solutions during 2 and 7 d. Five other samples served as a control group subjected directly to tensile testing. The bond strength values were obtained using a universal testing machine and compared statistically. The type of failure was assessed visually. No significant difference was found between the groups for the tested conditions used (p > 0.05). The most frequent failure mode was cohesive for Molloplast and Permaflex specimens, adhesive for Sofreliner Tough Medium, and a mixed type of failure was observed for GC Reline Soft material.     

The Effect of Surface Treatments on Tensile Bond Strength between a Silicone Soft Liner and a Heat-Cured Denture Base Resin

This study evaluated tensile bond strength of a denture soft lining material to a poly (methylmethacrylate) (PMMA) denture base resin subjected to different surface treatment modalities and thermocycling. The materials tested were a silicone-based liner, Molloplast B®, and a heat-cured denture base resin, Meliodent^TM. The denture soft lining material was packed against cured PMMA base resin, which was smoothed; sandblasted with 250-μm Al₂O₃ particles; or lased with a KTP laser; or against uncured PMMA dough (n = 10). In each group, five specimens were thermocycled in a water bath (5–55°C; 3000 cycles) before testing, whereas the other five were directly tested after 24 h. A tensile test was performed using a universal testing machine. Data showed that different treatment modalities of resin surfaces affected adhesion between these two materials and the highest bond values were recorded for cured/smoothed samples under each condition tested. Thermocycling of specimens had no significant reducing effect on measured bond strength values.     

Bond Strength of a Silicone Soft Lining Material to Poly(methyl methacrylate) Resin Treated with Maleic Anhydride and its Terpolymers

This study investigated the effectiveness of surface treatment of Poly (methyl methacrylate) (PMMA) denture base resin on tensile bond strength between PMMA/silicone-based soft liner. A total of 25 specimens were fabricated and assigned into five groups (n = 5). The surfaces of PMMA were treated with maleic anhydride, maleic anhydride-styrene-vinyl-acetate, n-butylmaleate-styrene-vinyl-acetate, or n-pentamaleate-styrene-vinyl-acetate prior to Primo adhesive primer application and silicone liner placement. The Primo adhesive primer on applied group untreated dentuse base resin served as control. The tensile test was performed using a universal testing machine. Fractured surfaces were observed under Scanning Electron Microscopy (SEM) and spectroscopic interpretation of the interfaces was done by Fourier Transform Infrared (FTIR). Test results showed that surface treatment increased interfacial strength giving the highest value for n-butylmaleate-styrene-vinyl acetate treated group. SEM micrographs revealed that the specimens with n-butylmaleate-styrene-vinyl-acetate and n-penta maleate-styrene-vinyl-acetate terpolymers underwent cohesive failure. FTIR analysis indicated secondary interactions such as hydrogen bonding, possibly on acrylic resin surfaces, caused by the use of maleic anhydride and its terpolymers, and the adhesive.     

Tensile bond strengths of silicone soft liners to two chemically different denture base resins

Silicone-based soft liners can be useful for patients who have difficulty to tolerate the hard-based dentures. However lack of adhesion to the denture base resin can be a problem that limits their clinical use. This study evaluated the tensile bond strengths (TBS) of four silicone soft liners (GC Soft, GC XSoft, Silagum, Mollosil) to two chemically different denture base resins, polymethyl methacrylate (PMMA) and urethane dimethacrylate (UDMA). Specimen consisted of soft liner material self-cured between two square plates of cured denture base resin measuring 20×20×4 mm. The circular bonding area of soft liner to each plate was 10 mm in diameter. Proprietary primer was applied to the surface of the denture base specimens before bonding following the manufacturers' recommendations. Ten specimens for each denture base-soft liner combination were prepared and tested under tension on a Shimadzu Universal Testing Machine at a cross head speed of 5 mm/min. The mode of failure was determined using a stereo-microscope at magnification of 10x. Two- and one-way ANOVA and post-hoc Dunnett-T3 and t-test were used for statistical analysis. There were significant differences in TBS values for the effect of denture base resins, soft liner and their interaction (p<0.05). The TBS of soft liners to PMMA was significantly higher than to UDMA denture base resins except for Silagum where no significant difference was observed. A mixed mode of failure was more common for all soft liners bonded to PMMA except for Silagum while adhesive failure was more predominant in the UDMA group.     

Evaluation of Laser Treatment on Reline-Base Composites

The effects of different laser treatments on some mechanical properties of acrylic resin and soft liner were investigated. A total of 60 test specimens were fabricated according to test requirements. The specimens were roughened with Potassium-ticanyl-Phosphate (KTP), Er:YAG, and Nd:YAG lasers before application of soft liner. The flexural, peel, and tensile bond strengths were measured using a universal testing machine. Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) spectra of surfaces were also obtained to evaluate changes on the lased surfaces. No significant difference was apparent between the tensile bond strength values of the groups. Although peel strength values obtained for each of the laser types were lower than those of the control group, flexural strength values were higher than those of the control specimens. The spectra of specimens showed that lasing led to some chemical changes on the resin surfaces. Physical changes on the treated surfaces were visualized by scanning electron microscopy (SEM) analysis. Results of this study suggest that such treatments may be warranted because of the increase in flexural strength.     

Evaluation of Laser Treatment on Reline-Base Composites

The effects of different laser treatments on some mechanical properties of acrylic resin and soft liner were investigated. A total of 60 test specimens were fabricated according to test requirements. The specimens were roughened with Potassium-ticanyl-Phosphate (KTP), Er:YAG, and Nd:YAG lasers before application of soft liner. The flexural, peel, and tensile bond strengths were measured using a universal testing machine. Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) spectra of surfaces were also obtained to evaluate changes on the lased surfaces. No significant difference was apparent between the tensile bond strength values of the groups. Although peel strength values obtained for each of the laser types were lower than those of the control group, flexural strength values were higher than those of the control specimens. The spectra of specimens showed that lasing led to some chemical changes on the resin surfaces. Physical changes on the treated surfaces were visualized by scanning electron microscopy (SEM) analysis. Results of this study suggest that such treatments may be warranted because of the increase in flexural strength.     

Tensile Bond Strength of a Highly Cross-Linked Denture Tooth to the Compression-Molded and Injection-Molded Denture Base Polymers

This study compared tensile bond strengths between conventional compression-molded heat (HC)-, auto (AP)-, and microwave-polymerized (MC) poly(methyl methacrylate)-based denture resins and a relatively new injection-molded, microwave-polymerized polyurethane based resin (MI) bonded to a highly cross-linked denture tooth. In the first part of the experiments, denture teeth were used as received. In the second part, they were treated with dichloromethane to see its effect on bonding of conventional denture bases (HCS and APS). Bond strength was tested in tension according to ADA specification No.15. The results showed that the HC group failed cohesively because of higher interface bonding (49.95 MPa) compared with those of the others (AP: 25.41 MPa; MC: 22.06 MPa; MI: 20.02 MPa). The application of dichloromethane improved bond strengths of HCS and APS groups (60.61 and 32.03 MPa, respectively). It was suggested that dichloromethane could be applied on the denture teeth ridge lap area prior to denture base processing to enhance adhesion between the tooth/resin.     

Shear bond strength of bis-acryl resin provisional material repaired using a flowable composite

This study investigated the shear bond strength of a bis-acryl composite repaired with a flowable composite after different surface treatments. Sixty standardized cylindrical silicone molds were filled with bis-acryl resin provisional material and then divided into six groups (n = 10 per group) to undergo different surface treatments. After a surface treatment had been performed, the flowable composite was injected directly into the cylinder of each specimen, and the specimens were then cured over a 10-mm-thick glass slide for 20 s. The shear bond strength was determined using a universal testing machine at a crosshead speed of 1.0 mm/min by placing a knife-edged blade immediately adjacent and parallel to the adhesive interface between the repair material (flowable composite) and the bis-acryl resin provisional material. The mean shear bond strengths ranged from 8.98 to 17.14 MPa. The highest mean shear bond strength corresponded to the bonding group (17.14 MPa), whereas the air-particle abrasion group exhibited the lowest mean shear bond strength (8.98 MPa). Surface treatment of bis-acryl resins with bonding appears to be a promising approach for improving repair bond strength, and the bonding group exhibited the highest levels of bond strength.     

Influence of oxygen plasma treatment parameters on the properties of carbon fiber

This study is focused on the impact of oxygen plasma treatment on properties of carbon fibers and interfacial adhesion behavior between the carbon fibers and epoxy resin. The influences of the main parameters of plasma treatment process, including duration, power, and flow rate of oxygen gas were studied in detail using interlaminar shear strength (ILSS) of carbon fiber composites. The ILSS of composites made of carbon fibers treated by oxygen plasma for 1 min, at power of 125 W, and oxygen flow rate of 100 sccm presented a maximum increase of 28% compared to composites made of untreated carbon fibers. Furthermore, carbon fibers were characterized by scanning electron microscopy (SEM), tensile strength test, attenuated total reflectance Fourier transform infrared (ATR-FTIR), and Raman spectroscopy analyses. It was found that the concentration of reactive functional groups on the fiber surface was increased after the plasma modification, as well the surface roughness, which finally improved the interfacial adhesion between carbon fibers and epoxy resin. However, high power and long exposure times could partly damage the surface of carbon fibers and decrease the tensile strength of filaments and ILSS of treated fiber composites.     

Effect of self-etching dual-curing universal adhesive system application on bond strength of dentin resinous liners dentin

Purpose: The aim of this study was to evaluate the influence of previous application of an adhesive system on bond strength of resinous liner materials to dentin. Methods: Ninety bovine incisors crowns had a 6 × 6 mm area of dentin exposed, with minimum of 2 mm thickness. They were embedded in acrylic resin, and the dentin was polished with P600 SiC sandpaper for 30 s to standardize the smear layer. The specimens were divided into 6 groups (n = 15) according to the application or not of a self-etching system (Futurabond U – Voco) and the type of resinous liner used: A+Ionoseal (adhesive and Ionoseal – Voco); Ionoseal (Ionoseal only); A+Vitrebond (adhesive and Vitrebond – 3M/ESPE); Vitrebond (Vitrebond only); A+Ionosit (adhesive and Ionosit – DMG) and Ionosit (Ionosit only). Adhesives were used following manufacturer’s instructions, and the liner materials were applied inside a 2-mm-depth matrix and light-cured for 20 s. The bond strength was measured by microtensile test, using a universal testing machine with a cross-speed of 1 mm/min. Data were analyzed using one-way ANOVA and Tukey’s test (p < 0.05). Results: The adhesive system application increased bond strength of all liners tested. Ionoseal presented the highest bond strength when the adhesive system was used and exhibited similar performance to Vitrebond without adhesive. Ionosit without adhesive showed the smallest bond strength compared with the other liners tested. Conclusion: The application of an adhesive system prior to the use of the resinous liners improved the bond strength to dentin and should be preconized.     

Adhesion potential of relining materials to polyamide and PMMA-based denture base materials: effect of surface conditioning methods

This study evaluated the bond strength of relining materials to different denture base materials polyamide and polymethylmethacrylate denture base materials after various surface conditioning methods. Denture base resin specimens (N?=?128; n?=?8 per group) (10?×?10?×?2.5?mm³) were fabricated out of injection-moulded thermoplastic polyamide resin (POL) (Deflex) and heat-polymerized polymethylmethacrylate (PMMA, Dura Dent) (HC). The specimens were randomly divided into 4 main groups according to different surface conditioning methods: (a) No conditioning, control (C), (b) grinding with green stone (G), (c) application of primer (V), (d) silica coating with Al₂O₃ particles coated with SiO₂ (Rocatec) (R). Half of the specimens in each group received auto-polymerized hard relining resin (GC, GC Reline Hard) and the other half PMMA based relining resin (SC, Dura Dent). After thermocycling (×5000), the bonded specimens were tested under tensile forces (0.5?mm/min). Data (MPa) were analyzed using Mann–Whitney U and Kruskal–Wallis tests (alpha = 0.05). Bond strength of relining resins were significantly higher to PMMA than to POL, regardless of the conditioning method (p?<?0.05). While R positively affected the bond strength results (p?<?0.05) (4.99?±?1.65–3.27?±?1.31), application V or G did not show significant effect to POL-relining resin adhesion. After R conditioning, bond strength values were significantly higher in HC-GC group (7.48?±?2.32) than POL-GC group (3.27?±?1.31) (p?<?0.05). Adhesion of auto-polymerized relining materials to thermoplastic polyamide or polymethylmethacrylate denture resins could be improved after surface conditioning with silica-coating.     

Bond Strength of a Silicone Soft Lining Material to Poly(methyl methacrylate) Resin Treated with Maleic Anhydride and its Terpolymers

This study investigated the effectiveness of surface treatment of Poly (methyl methacrylate) (PMMA) denture base resin on tensile bond strength between PMMA/silicone-based soft liner. A total of 25 specimens were fabricated and assigned into five groups (n = 5). The surfaces of PMMA were treated with maleic anhydride, maleic anhydride-styrene-vinyl-acetate, n-butylmaleate-styrene-vinyl-acetate, or n-pentamaleate-styrene-vinyl-acetate prior to Primo adhesive primer application and silicone liner placement. The Primo adhesive primer on applied group untreated dentuse base resin served as control. The tensile test was performed using a universal testing machine. Fractured surfaces were observed under Scanning Electron Microscopy (SEM) and spectroscopic interpretation of the interfaces was done by Fourier Transform Infrared (FTIR). Test results showed that surface treatment increased interfacial strength giving the highest value for n-butylmaleate-styrene-vinyl acetate treated group. SEM micrographs revealed that the specimens with n-butylmaleate-styrene-vinyl-acetate and n-penta maleate-styrene-vinyl-acetate terpolymers underwent cohesive failure. FTIR analysis indicated secondary interactions such as hydrogen bonding, possibly on acrylic resin surfaces, caused by the use of maleic anhydride and its terpolymers, and the adhesive.     

Effect of nonthermal plasma treatment on surface roughness and bond strength between veneer ceramic and zirconia core

This in vitro study evaluated the effect of nonthermal plasma (NTP) treatment on the surface roughness (Ra) of the zirconia and the shear bond strength (SBS) between the veneer ceramic and the zirconia. Ninety zirconia specimens were divided into six groups according to the surface treatments applied: control with no treatment; sandblasting with 50-μm Al₂O₃ particles; oxygen plasma treated for 5 min; oxygen plasma treated for 10 min; argon plasma treated for 5 min; and argon plasma treated for 10 min. Ra values were measured using a profilometer. Specimens (n = 12) were then veneered with a nano-fluorapatite ceramic, and the SBS test was performed. Scanning electron microscopy, atomic force microscopy, and X-ray diffraction analyses were performed. The sandblasting procedure significantly increased the surface roughness; however, the plasma groups showed similar Ra values compared to the control group. NTP and sandblasting treatment significantly increased the bond strength and led to higher SBS values than the control. Plasma application did not induce phase transformation; however, sandblasting caused monoclinic phase transformation of the zirconia. NTP application (either oxygen or argon) can enhance the bond strength between the veneer ceramic and the zirconia core without altering the surface morphology or causing zirconia phase transformation.     

可见光固化义齿软衬材料与义齿基托树脂PMMA的粘接研究

本文配制了用于提高义齿软村材料与PMMA粘接强度的底胶，测试了底腔中稀释剂含量对粘接强度的影响，观察了粘接接头耐人工唾液的性能。     

Performance of protein-based wood bioadhesives and development of small-scale test method for characterizing properties of adhesive-bonded wood specimens

A small-scale test method to measure the tensile strength of adhesive-bonded wood strip specimens was developed by simple modification of commercially available binder clips. As bioadhesives, soy protein concentrate (SPC) and gelatin resins were prepared and were evaluated for shear and tensile bond strengths of bamboo and maple wood-bonded specimens. Titebond-II (TB-II), a commercially available wood glue was also tested to compare its bonding property to SPC and gelatin-based bioadhesives. TB-II glue showed the highest shear and tensile bond strengths with both bamboo and maple wood strips. Hot-pressing increased the shear and tensile bond strengths of SPC resin with wood specimens by 500% while the increase for gelatin resins was up to 200%. Roughness profile and surface properties were also characterized with an optical interferometric profiler and a scanning electron microscope. The results indicated that rougher surface significantly increased the bond strengths in both shear and tensile modes.     

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.     

Effect of Microwave Treatment on the Shear Bond Strength of Denture Tooth/Acrylic Resin

This study investigated the effect of microwave treatment on the shear bond strength of the denture tooth to acrylic resin adhesion, when the glossy ridge laps were unmodified, abraded, grooved, or etched by monomer. Eighty specimens (n = 10) were polymerized in a hot bath at 74°C for 9 hours, and deflasked after flask cooling. Specimens were soaked in 150 mL of distilled water and submitted to microwave treatment in a domestic microwave oven calibrated at 650 W for 3 minutes. Control specimens were not microwave treated. The shear bond strength test was performed in an Instron machine with a cross-speed of 1mm/minute. The ultimate fracture load value was transformed into shear bond strength as a function of the bonding area. Collected data were submitted to ANOVA and Tukey's test (α = .05). Treatment by microwave energy significantly decreased (p < .05%) the shear bond strength values in all ridge lap conditions used for the denture tooth/resin adhesion.     

The effect of atmospheric pressure helium plasma treatment on the surface and mechanical properties of ultrahigh-modulus polyethylene fibers

Ultrahigh-modulus polyethylene fibers were treated with atmospheric pressure He plasma on a capacitively coupled device at a frequency of 7.5 kHz and a He partial vapor pressure of 3.43 × 10³ Pa. The fibers were treated for 0, 1, and 2 min. Microscopic analysis showed that the surfaces of the fibers treated with He plasma were etched and that the 2-min He plasma-treated group had rougher surfaces than the 1-min He plasma-treated group. XPS analysis showed a 200% increase in the oxygen content and a 200% increase in the concentration of C—O bonds (from 11.4% to 31%) and the appearance of C=O bonds (from 0% to 7.6%) on the surface of plasma-treated fibers for the 2-min He plasma-treated group. In the microbond test, the 2-min He plasma-treated group had a 100% increase of interfacial shear strength over that of the control group, while the 1-min He plasma-treated group did not show a significant difference from the control group. The 2-min He plasma-treated group also showed a 14% higher single-fiber tensile strength than the control group.     

Effect of methyl methacrylate monomer on bond strength of denture base resin to acrylic teeth

Bond failures at the acrylic teeth and denture base resin interface are still a common clinical problem in prosthodontics. The effect of methyl methacrylate (MMA) monomer on the bond strength of three types of denture base resins (Acron MC, Lucitone 550 and QC-20) to two types of acrylic teeth (Biotone and Trilux) was evaluated. Twenty specimens were produced for each denture base resin/acrylic tooth combination and were randomly divided into control (acrylic teeth received no surface treatment) and experimental groups (MMA was applied to the surface of the acrylic teeth for 180 s) and were submitted to shear tests (1 mm/min). Data (MPa) were analyzed using three-way ANOVA/Student's test (α=0.05). MMA increased the bond strength of Lucitone denture base resins and decreased the bond strength of QC-20. No difference was detected for the bond strength of Acron MC base resin after treatment with MMA.     

Two-step vs. one-step conditioning systems and adhesive interface of glass ceramic surface and resin systems

The effect of two-step and one-step ceramic surface conditioning/priming, and subjecting to exposure with boiling water on adhesion strength of resin cements was evaluated. Rectangular shaped specimens were cut from CAD blocks of E-max (Ivoclar Vivadent) and Mark II (VITA Zahnfabrik) and randomly assigned to two main study groups. Group one specimens’ surfaces were conditioned using the two-step conditioning/priming procedure and group two specimens were treated using the one-step conditioning/priming system. After treating, 3 mm thick resin cement layer was applied onto the surface using a split stainless steel mold. Each group was further divided into four subgroups (n = 10) depending on type of resin cement applied and subjecting to exposure in boiling water. Adhesion strength of all the specimens was measured using the universal material testing machine, results were tabulated and subjected to statistical analysis at a significance level of p < 0.05. Adhesive resin showed higher values of 22.05 and 18.65 MPa with E-max and Mark II respectively, and resin composites showed 18.13 and 15.13 MPa with E-max and Mark II respectively, when two-step conditioning system was employed. Majority of the adhesive resin specimens showed cohesive failure in cement. Subjecting the specimens to exposure in boiling water for 24 h not only showed adhesive failure but also significantly reduced adhesion strength of adhesive resin and resin composite. The significance of the study is that, the traditional two-step ceramic surface conditioning is more effective than the one-step conditioning and unfilled adhesive resin provides better adhesion strength.