Bond strength of acrylic teeth to denture base resin after various surface conditioning methods before and after thermocycling

This study aimed to evaluate the durability of adhesion between acrylic teeth and denture base acrylic resin. The base surfaces of 24 acrylic teeth were flatted and submitted to 4 surface treatment methods: SM1 (control): No SM; SM2: application of a methyl methacrylate-based bonding agent (Vitacol); SM3: air abrasion with 30-μm silicone oxide plus silane; SM4: SM3 plus SM2. A heat-polymerized acrylic resin was applied to the teeth. Thereafter, bar specimens were produced for the microtensile test at dry and thermocyled conditions (60 days water storage followed by 12,000 cycles). The results showed that bond strength was significantly affected by the SM (P < .0001) (SM4 = SM2 > SM3 > SM1) and storage regimens (P < .0001) (dry > thermocycled). The methyl methacrylate-based adhesive showed the highest bond strength.

The effect of water immersion on the shear bond strength between chairside reline and denture base acrylic resins: Basic science research

Purpose: The effect of water immersion on the shear bond strength (SBS) between 1 heat-polymerizing acrylic resin (Lucitone 550-L) and 4 autopolymerizing reline resins (Kooliner-K, New Truliner-N, Tokuso Rebase Fast-T, Ufi Gel Hard-U) was investigated. Specimens relined with resin L were also evaluated. Materials and Methods: One hundred sixty cylinders (20 × 20 mm) of L denture base resin were processed, and the reline resins were packed on the prepared bonding surfaces using a split-mold (3.5 × 5.0 mm). Shear tests (0.5 mm/min) were performed on the specimens (n = 8) after polymerization (control), and after immersion in water at 37°C for 7, 90, and 180 days. All fractured surfaces were examined by scanning electron microscopy (SEM) to calculate the percentage of cohesive fracture (PCF). Shear data were analyzed with 2-way ANOVA and Tukey's test; Kruskall-Wallis test was used to analyze PCF data (α = 0.05). Results: After 90 days water immersion, an increase in the mean SBS was observed for U (11.13 to 16.53 MPa; p < 0.001) and T (9.08 to 13.24 MPa, p = 0.035), whereas resin L showed a decrease (21.74 MPa to 14.96 MPa; p < 0.001). The SBS of resins K (8.44 MPa) and N (7.98 MPa) remained unaffected. The mean PCF was lower than 32.6% for K, N, and T, and higher than 65.6% for U and L. Conclusions: Long-term water immersion did not adversely affect the bond of materials K, N, T, and U and decreased the values of resin L. Materials L and U failed cohesively, and K, N, and T failed adhesively. © 2007 by The American College of Prosthodontists.

Impact strength of denture base and reline acrylic resins subjected to long-term water immersion

Water may influence the mechanical properties of the acrylic resins. Thus, the effect of water storage on the impact strength (IS) of one denture base (Lucitone 550 - L) and four reline resins (Tokuyama Rebase II - T; UfiGel Hard - U; Kooliner - K; New Truliner - NT) was evaluated. Bars of L were made (60 x 6 x 2 mm) and relined (2 mm) with T, U, K, NT and L. Intact specimens of each material (60 x 6 x 4 mm) were also fabricated for comparative purposes. Specimens were submitted to Charpy impact tests without water storage (control) and after immersion in water for 7, 90 and 180 days. Data (kJ/m 2) analyzed by two-way ANOVA and Tukey's test (p=0.05) revealed that after 90 days, U exhibited an increase in the IS (0.93) compared to 7 days (0.58). K (1.48) and L/K (7.21) exhibited a decrease at the 7-day period (1.01 and 3.23, respectively). NT (0.60) showed an increase in the IS after 180 days (1.52), whereas L/ NT (7.70) showed a decrease (3.17). Water immersion improved the IS of U and NT, and decreased the IS of K, L/K, and L/NT. Water may affect differently the IS of acrylic resins and, consequently, the resistance to fracture of relined denture bases.

Adhesion of real seal to human root dentin treated with different solutions

The aim of this study was to evaluate the effects of different irrigants on sealer-dentin bond strength when using Real Seal. Thirty single-rooted teeth were divided into 3 groups. In one group, the teeth were irrigated with 3 mL of 2.5% NaOCl after each file change, flushed with 17% EDTA for 3 min and finally rinsed with 3 mL of 2.5% NaOCl. In the other two groups, rinse with NaOCl was replaced with 2% chlorhexidine gluconate (CHX) and 0.9% saline, respectively. Each root was sectioned transversally into apical, middle and coronal thirds to obtain 2-mm-thick slices. Each slice was filled with Real Seal and Resilon. Push-out test was used to analyze bond strength and failure modes were classified as adhesive, cohesive or mixed, according to SEM observations. The push-out test did not reveal any statistically significant difference (p>0.05) between the irrigants. However, the groups exhibited significantly different (p<0.05) bond strengths in terms of the root canal third. Higher bond strength was observed at the apical third when compared with coronal third, while middle third presented intermediary values. Fifteen specimens were analyzed by SEM (5 per group). Eleven specimens exhibited adhesive failures (5 in saline, 4 in NaOCl and 2 in CHX group); 2 cohesive failures were observed in the CHX group, and 1 mixed failure each was observed in the CHX and NaOCl groups. The tested irrigants did not influence the bond strength of Resilon and Real Seal to dentin. The apical third exhibited higher mean bond strengths and adhesive failures were predominant.

Effect of seating forces on cement-ceramic adhesion in microtensile bond tests

Objectives: The aim of this study was to evaluate the effect of different seating forces during cementation in cement-ceramic microtensile bond strength (μTBS). Materials and methods: Forty-five blocks (5 × 5 × 4 mm3) of a glass-infiltrated alumina-based ceramic (In-Ceram Alumina) were fabricated according to the manufacturer's instructions and duplicated in resin composite. Ceramic surfaces were polished, cleaned for 10 min in an ultrasonic bath, silica coated using a laboratory type of air abrasion device, and silanized. Each treated ceramic block was then randomly assigned to five groups (n = 9) and cemented to a composite block under five seating forces (10 g, 50 g, 100 g, 500 g, and 750 g) using a dual-cured resin cement (Panavia F). The ceramic-cement-composite assemblies were cut under coolant water to obtain bar specimens (1 mm × 0. 8 mm2). The μTBS tests were performed in a universal testing machine (1 mm/min). The mean bond strengths values were statistically analyzed using one-way ANOVA (α ≤ 0. 05). Results: Different seating forces resulted in no significant difference in the μTBS results ranging between 13. 1 ± 4. 7 and 18. 8 ± 2. 1 MPa (p = 0. 13) and no significant differences among cement thickness. Conclusions: Excessive seating forces during cementation seem not to affect the μTBS results. Clinical relevance: Excessive forces during the seating of single all-ceramic restorations cementation seem to display the same tensile bond strength to the resin cement. © 2012 Springer-Verlag.

Bond strength of adhesive systems with different solvents to dry and wet dentin

Aim: This study evaluates bond strength between dentin and composite using adhesives with different solvents to dry and wet dentin. Materials and methods: Ninety bovine incisors were used; the vestibular surfaces were worn by the exposure of an area with a diameter of 4 mm of dentin. The specimens were divided into 6 groups, according to the type of adhesive used and hydratation stals: Group SB-wet: Single Bond 2 in wet dentin, Group SBdry: Single Bond 2 in dry dentin, Group SL-wet: Solobond M in wet dentin, Group SL-dry: Solobond M in dentin dry. Group XPwet: XP Bond in wet dentin, Group XP-dry: XP Bond in dentin dry. They were cut to obtain specimens in the shape of stick with 1 × 1 mm and subjected to microtensile test in universal testing machine with a cross speed of 1mm/min. The data were analyzed with ANOVA and Tukey's tests (5%). Results: ANOVA showed significant differences for surface treatment and interaction, but no difference was found for adhesive factor. The Tukey's test showed that the samples with wet dentin shown higher values of bond strength. Conclusion: The adhesive did not influence in the bond strength. The groups with wet dentin showed higher values of bond strength than groups with dry dentin.

Atmospheric plasma treatment of carbon fibers for enhancement of their adhesion properties

Plasma processing of carbon fibers (CFs) is aimed to provide better contact and adhesion between individual plies without decrease in the CF mechanical resistance. This paper deals with surface modification of CFs by an atmospheric pressure dielectric barrier discharge (DBD) for enhancing the adhesion between the CF and the polymeric matrix. The scanning electron microscopy of the treated samples revealed many small particles distributed over entire surface of the fiber. These particles are product of the fiber surface etching during the DBD treatment that removes the epoxy layer covering as-received samples. The alteration of the CF surface morphology was also confirmed by the Atomic force microscopy (AFM), which indicated that the CF roughness increased as a result of the plasma treatment. The analysis of the surface chemical composition provided by X-ray photoelectron spectroscopy showed that oxygen and nitrogen atoms are incorporated onto the surface. The polar oxygen groups formed on the surface lead to the increasing of the CF surface energy. The results of interlaminar shear strength test (short beam) of CFs/polypropylene composites demonstrated a greater shear resistance of the composites made with CFs treated by DBD than the one with untreated fibers. Both the increase in surface roughness and the surface oxidation contribute for the enhancement of CF adhesion properties. © 2012 IEEE.

Effects of extreme cooling methods on mechanical properties and shear bond strength of bilayered porcelain/3Y-TZP specimens

Objectives: This study investigated the effect of extreme cooling methods on the flexural strength, reliability and shear bond strength of veneer porcelain for zirconia. Methods: Vita VM9 porcelain was sintered on zirconia bar specimens and cooled by one of the following methods: inside a switched-off furnace (slow), at room temperature (normal) or immediately by compressed air (fast). Three-point flexural strength tests (FS) were performed on specimens with porcelain under tension (PT, n = 30) and zirconia under tension (ZT, n = 30). Shear bond strength tests (SBS, n = 15) were performed on cylindrical blocks of porcelain, which were applied on zirconia plates. Data were submitted to one-way ANOVA and Tukey's post hoc tests (p < 0.05). Weibull analysis was performed on the PT and ZT configurations. Results: One-way ANOVA for the PT configuration was significant, and Tukey's test revealed that fast cooling leads to significantly higher values (p < 0.01) than the other cooling methods. One-way ANOVA for the ZT configuration was not significant (p = 0.06). Weibull analysis showed that normal cooling had slightly higher reliability for both the PT and ZT configurations. Statistical tests showed that slow cooling decreased the SBS value (p < 0.01) and showed less adhesive fracture modes than the other cooling methods. Clinical Significance: Slow cooling seems to affect the veneer resistance and adhesion to the zirconia core; however, the reliability of fast cooling was slightly lower than that of the other methods. © 2013 Elsevier Ltd.

Durability of Adhesion between Feldspathic Ceramic and Resin Cements: Effect of Adhesive Resin, Polymerization Mode of Resin Cement, and Aging

Purpose: Adhesive cementation is an important step for restorations made of feldspathic ceramic as it increases the strength of such materials. Incorrect selection of the adhesive resin and the resin cement to adhere to the ceramic surface and their durability against aging can affect the adhesion between these materials and the clinical performance. This study evaluated the effect of adhesive resins with different pHs, resin cements with different polymerization modes, and aging on the bond strength to feldspathic ceramic. Materials and Methods: One surface of feldspathic ceramic blocks (VM7) (N = 90) (6.4 × 6.4 × 4.8 mm3) was conditioned with 10% hydrofluoric acid for 20 seconds, washed/dried, and silanized. Three adhesive resins (Scotchbond Multi-Purpose Plus [SBMP], pH: 5.6; Single Bond [SB], pH: 3.4; and Prime&Bond NT [NT], pH: 1.7) were applied on the ceramic surfaces (n = 30 per adhesive). For each adhesive group, three resin cements with different polymerization modes were applied (n = 10 per cement): photo-polymerized (Variolink II base), dual polymerized (Variolink II base + catalyst), and chemically polymerized (C&B). The bonded ceramic blocks were stored in water (37°C) for 24 hours and sectioned to produce beam specimens (cross-sectional bonded area: 1 ± 0.1 mm2). The beams of each block were randomly divided into two conditions: Dry, microtensile test immediately after cutting; TC, test was performed after thermocycling (12,000×, 5°C to 55°C) and water storage at 37°C for 150 days. Considering the three factors of the study (adhesive [3 levels], resin cement [3 levels], aging [2 levels]), 18 groups were studied. The microtensile bond strength data were analyzed using 3-way ANOVA and Tukey's post hoc test (α= 0.05). Results: Adhesive resin type (p < 0.001) and the resin cement affected the mean bond strength (p= 0.0003) (3-way ANOVA). The NT adhesive associated with the chemically polymerized resin cement in both dry (8.8 ± 6.8 MPa) and aged conditions (6.9 ± 5.9 MPa) presented statistically lower bond strength results, while the SBMP adhesive resin, regardless of the resin cement type, presented the highest results (15.4 to 18.5 and 14.3 to 18.9 MPa) in both dry and aged conditions, respectively (Tukey's test). Conclusion: Application of a low-pH adhesive resin onto a hydrofluoric acid etched and silanized feldspathic ceramic surface in combination with chemically polymerized resin cement did not deliver favorable results. The use of adhesive resin with high pH could be clinically advised for the photo-, dual-, and chemically polymerized resin cements tested. © 2012 by the American College of Prosthodontists.

Effect of immersion cleansers on the bond strength between a denture base resin and acrylic resin teeth

The aim of the present study was to assess the shear bond strength between a heat-polymerized denture base resin and acrylic resin teeth after immersion in different denture cleansers by simulating a 180-day use. Two acrylic teeth (Biotone, Biotone IPN, Dentsply Ind. e Com., Rio de Janeiro, RJ, Brazil) were chosen for bonding to a heat-polymerized denture base resin (Lucitone 550- Dentsply Ind. e Com., Rio de Janeiro, RJ, Brazil). Eighty specimens were produced and divided into eight groups (n=10) according to their experimental condition (distilled water, 2% chlorhexidine digluconate, 1% sodium hypochlorite and Corega Tabs). Shear bond strength tests (MPa) were performed with a universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed by two-way analysis of variance (ANOVA) and Student-Newman-Keuls' multiple comparisons post hoc analysis (α=.05). The shear bond strength results revealed statistically significant differences between the groups. For the Biotone IPN tooth, significantly lower shear bond strength values were found for the group immersed in sodium-perborate solution (4.48±2.18 MPa) than for the group immersed in distilled water (control group) (10.83±1.84 MPa). For Biotone, significantly higher bond strength values (10.04±3.28 MPa) were found for the group immersed in Corega Tabs than for the control group (5.45±2.93 MPa). The immersion in denture cleanser solutions was more detrimental to the conventional acrylic denture tooth (Biotone) than to the highly cross-linked denture tooth (Biotone IPN). However, this effect was not observed for the groups immersed in Corega Tabs solution, regardless of the type of denture tooth. © 2013 Elsevier Ltd.

Effect of fiber surface on flexural strength in carbon fabric reinforced epoxy composites

The effect of carbon fiber surface characteristics on flexural properties of structural composites is studied in this work. Two types of intermediate modulus carbon fibers were used: T800HB and IM7. Results revealed that higher mechanical properties are linked with higher interfacial adhesion. Morphologies and chemical compositions of commercial carbon fibers (CF) were characterized by Fourier Transformed Infra Red (FTIR) and Scanning Electronic Microscopy (SEM). Comparing the results, the T800HB apparently has more roughness, since the IM7 seems to be recovered for a polymeric film. On other hand, the IM7 one shows higher interactivity with epoxy resin system Cycom 890 RTM. Composites produced with Resin Transfer Molding (RTM) were tested on a flexural trial. Interfacial adhesion difference was showed with SEM and Dynamic Mechanical Analyses (DMA), justifying the higher flexural behavior of composites made with IM7 fibers. © 2013 Elsevier B.V. All rights reserved.

Evaluation of metallic brackets adhesion after the use of bleaching gels with and without amorphous calcium phosphate (ACP): in vitro study

OBJETIVO: avaliar, in vitro, a influência do clareamento dentário com gel contendo fosfato de cálcio amorfo (ACP) na resistência da união adesiva de braquetes metálicos. MÉTODOS: trinta e seis dentes incisivos bovinos foram seccionados no limite coronorradicular e tiveram suas coroas incluídas em cilindros de PVC. Os corpos de prova foram divididos em três grupos (n = 12), de acordo com a realização do tratamento clareador e tipo de gel utilizado, sendo: G1 (controle) - sem clareamento; G2 - clareamento com gel sem ACP (Whiteness Perfect, FGM); G3 - clareamento com gel contendo ACP (Nite White ACP, Discus Dental). Os grupos G2 e G3 foram submetidos a 14 ciclos de clareamento, seguidos de intervalo de espera de 15 dias para a fixação adesiva dos braquetes metálicos. O ensaio mecânico de cisalhamento foi realizado em máquina universal Kratos, com velocidade de 0,5mm/min. Após o teste mecânico, os corpos de prova foram avaliados quanto ao índice de remanescente adesivo (ARI). Os resultados foram submetidos à ANOVA, ao teste de Tukey e ao de Kruskall-Wallis (α = 5%). RESULTADOS: diferenças significativas foram observadas entre os grupos testados. O grupo controle G1 (11,1MPa) mostrou uma resistência ao cisalhamento estatisticamente superior aos grupos submetidos ao clareamento (G2 = 5,40MPa; G3 = 3,73MPa), os quais não diferiram entre si. Não se observou diferença significativa para o ARI entre os grupos estudados. CONCLUSÃO: o clareamento dentário reduz a resistência da união adesiva de braquetes metálicos, enquanto a presença de ACP no gel clareador não influencia os resultados encontrados.

Comparison of Physicochemical Surface Conditioning Methods for Adhesion of bis-GMA Resin Cement to Particulate Filler Composite and Surface Characterization

This study compared the effect of physicochemical surface conditioning methods on the adhesion of bis-GMA-based resin cement to particulate filler composite (PFC) used for indirect dental restorations. PFC blocks (N (block)=54, n (block)=9 per group) were polymerized and randomly subjected to one of the following surface conditioning methods: a) No conditioning (Control-C), b) Hydrofluoric acid (HF)etching for 60s (AE60), c) HF for 90s (AE90), d) HF for 120s (AE120), e) HF for 180s (AE180), and f) air-abrasion with 30 mu m silica-coated alumina particles (AB). The conditioned surfaces were silanized with an MPS silane, and an adhesive resin was applied. Resin composite blocks were bonded to PFC using resin cement and photo-polymerized. PFC-cement-resin composite blocks were cut under coolant water to obtain bar specimens (1mmx0.8mm). Microtensile bond strength test (mu TBS)was performed in a universal testing machine (1mm/min). After debonding, failure modes were classified using stereomicroscopy. Surface characterization was performed on a set of separate specimen surfaces using Scanning Electron Microscopy (SEM), X-Ray Dispersive Spectroscopy (XDS), X-Ray Photoelectron Spectroscopy (XPS), and Fourier Transform-Raman Spectroscopy (FT-RS). Mean mu TBS (MPa) of C (35.6 +/- 4.9) was significantly lower than those of other groups (40.2 +/- 5.6-47.4 +/- 6.1) (p<0.05). The highest mu TBS was obtained in Group AB (47.4 +/- 6.1). Prolonged duration of HF etching increased the results (AE180: 41.9 +/- 7), but was not significantly different than that of AB (p>0.05). Failure types were predominantly cohesive in PFC (34 out of 54) followed by cohesive failure in the cement (16 out of 54). Degree of conversion (DC) of the PFC was 63 +/- 10%. SEM analysis showed increased irregularities on PFC surfaces with the increased etching time. Chemical surface analyses with XPS and FT-RS indicated 11-70% silane on the PFC surfaces that contributed to improved bond strength compared to Group C that presented 5% silane, which seemed to be a threshold. Group AB displayed 83% SiO2 and 17% silane on the surfaces.

Evaluation of Resin Bond Strength to Yttria-stabilized Tetragonal Zirconia and Framework Marginal Fit: Comparison of Different Surface Conditionings

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Adhesion of substrate-adherent combinations for early composite repairs: Effect of intermediate adhesive resin application

This study evaluated the effect of intermediate adhesive resin application (IAR) on tensile bond strength (TBS) for early composite repairs in situations where substrate and repair composite bonded together were once of the same kind with the substrate (similar) and once other than the substrate material (dissimilar). Specimens from three types of composites (TPH Spectrum (TPH), Charisma (CHA) and Filtek Z250 (Z250)) were fabricated. The specimens in each composite group (n=72) were randomly divided into six subgroups (n=12). In each composite group, the similar and two dissimilar composites were bonded onto the substrates once using an IAR (Adper Single Bond Plus) and once without. After water storage for I week at 37 degrees C, substrate-adherent combinations were submitted to tensile test. Data were analyzed with three-way ANOVA and Tukey's tests (alpha=0.05). The substrate-adherent combination (p=0.0001), adherent (repair) composite (p=0.0001), and application of IAR (p=0.0001) significantly affected the results. Utilization of IAR improved the repair bond strength for all composite combinations. (C) 2013 Elsevier Ltd. All rights reserved.