Comparison of methanol/hydrochloric,ferric chloride acid versus tribochemical silica coating for adhesion of resin cement to zirconium dioxide

This study compared air-abrasion and etching regimens on adhesion of resin luting agent to zirconium dioxide. Ceramic specimens (LAVA, 3 M ESPE) (N = 16) were embedded in acrylic resin and exposed surfaces were polished. The specimens were randomly assigned into four groups (n = 12, 3 specimens for each disc): SC: Air-borne particle abrasion (30 μm aluminum oxide particles coated with silica, CoJet, 3 M ESPE); MH: Heated chemical solution (Methanol-800 mL; 37% Hydrochloric Acid-200 mL; Ferric Chloride-2 g) at 100 °C for 30 min, MHP: Primer (Metal/Zirconia Primer, Ivoclar Vivadent) + MH, P: Primer only (Metal/Zirconia Primer). Cylindrical molds (internal diameter: 0.7 mm; height: 1.5 mm) were placed on each conditioned specimen, filled with resin cement (Multilink Automix) and photo-polymerized for 60 s. After 24 h, the molds were removed and the specimens were stored in distilled water at 37 °C for six months). Microshear test was performed in a Universal Testing Machine (1 mm/min). Failures types were classified as adhesive, mixed, or cohesive. In another set of specimens (n = 2 per group) contact angle measurements were recorded. Data were analyzed statistically using Kruskal–Wallis and Dunn’s tests (α = 0.05). The surface conditioning method significantly affected the mean bond strength (MPa) (p < 0.0001): SC(18.3 ± 0.3)^a < P(5.00 ± 0.07)^b < MHP(4.7 ± 0.08)^c < MH(0.84 ± 0.01)^c. While Group SC showed mainly adhesive (58%) and mixed (41.7%) failure types, groups MH, MHP, and P presented exclusively adhesive failures. SC, MHP, and P (29–32°) showed lower contact angle than MH (78.9°). Volume loss was the highest with MHP (9.92 μl) followed by SC (9.67 μl).     

Analysis of structural,morphological alterations,wettability characteristics and adhesion to enamel after various surface conditioning methods

Minimal invasive dental reconstructions and orthodontic appliances are bonded to enamel without removing the enamel with rotating instruments but the top layer of enamel may be partially aprismatic and impair adhesion. The objectives of this study were to investigate the effect of mechanical surface conditioning methods for removing enamel on its structural, morphological alterations, wettability characteristics, and adhesion of resin-based cement to the conditioned surfaces. Maxillary human incisors (N = 40, n_quadrant = 160) were obtained and coronal sections were embedded in acrylic with their labial surfaces exposed. The teeth were randomly divided into four groups and the enamel surface of each tooth was divided into four quadrants. The surfaces were conditioned in a clockwise manner by one of the following methods: (1) Non-conditioned enamel acted as the control group (C); (2) Silicone-coated disk (Sof-Lex disc, Black, 3 M ESPE) (SD); (3) Diamond bur at slow speed (DB) and (4) Airborne particle abrasion (50 μm Al₂O₃, 2 bar, 5 s) (AA). Surface roughness was measured at each quadrant using a non-contact digital profilometer and contact angle measurements were performed using a goniometer. Enamel surfaces were then etched with 37% H₃PO₄ for 60 s and roughness and wettability measurements were repeated. The enamel surfaces in each quadrant received resin composite luting cement (Variolink II, Ivoclar Vivadent) incrementally in a polyethylene mold (diameter: 1 mm²; height: 4 mm) and photopolymerized. The specimens were stored in distilled water for 24 h at 37 °C until the testing procedures and then shear force was applied to the adhesive interface until failure occurred in a Universal Testing Machine (0.5 mm/min). Microshear bond (μSBS) was calculated by dividing the maximum load (N) by the bonding surface area of the resin cement. Representative enamel surfaces were analyzed under the scanning electron microscope (SEM) (x5000) to assess the surface morphology. Failure types were analyzed using optical microscope and SEM. Data (MPa) were analyzed using one-way ANOVA and Tukey`s test for each parameter and Linear model for group comparisons (α = 0.05). Surface conditioning method significantly affected the adhesion results (p < 0.001), surface roughness (p = 0.017), and contact angle (p < 0.001). Interaction terms were significant (p > 0.05). AA (338 ± 182) created significantly higher surface roughness compared to SD (308 ± 180) and DB (242 ± 197) (p < 0.05). After etching with 37% H₃PO₄, DB (307 ± 223) resulted in significantly lower roughness than those of SD (385 ± 173) and AA (414 ± 193) (p < 0.05). AA (40 ± 11) delivered significantly lower contact angle compared to those of SD (61 ± 9) and DB (59 ± 10). After etching with 37% H₃PO₄, AA (42 ± 10) and DB (50 ± 10) presented the lowest contact angle (p < 0.05). Mean μSBS results (MPa) showed significant difference between the experimental groups (p = 0.011) and were in descending order as follows: DB (20 ± 8)^a?a b < C (12 ± 5)^b. Failure types were predominantly mixed failure type between the enamel and the resin cement with more than half of the resin remained on the enamel surface (32 to 33 out of 40) in all groups. Cohesive failure in the enamel was not observed in any of the groups. SEM analysis showed that AA group leaves abundant particles on the enamel surface and after DB and AA, etching could not remove the particles completely and expose the enamel prisms.     

Effects of different particle deposition parameters on adhesion of resin cement to zirconium dioxide and phase transformation

This study evaluated the effect of air-abrasion parameters such as particle size, distance, and time on adhesion of resin cement to zirconium dioxide (Y-TZP) and t→m phase transformation. Y-TZP blocks (N = 80) (In-Ceram YZ, Vita) (4 mm^3?×?4 mm^3?×?3 mm³) were assigned into eight groups (n = 10): air-abrasion with 30 μm (CoJet Sand, S30) and 110 μm (Rocatec-Plus, S110) silica-coated alumina particles, applied for either for 10–20 s (T = time), from a distance of 10–20 mm (D = distance), composing the following groups: S₃₀T₁₀D₁₀, S₃₀T₁₀D₂₀, S₃₀T₂₀D₁₀, S₃₀T₂₀D₂₀, S₁₁₀T₁₀D₁₀, S₁₁₀T₁₀D₂₀, S₁₁₀T₂₀D₁₀, and S₁₁₀T₂₀D₂₀. Resin composite (RelyX ARC) was bonded to Y-TZP blocks in polyethylene molds. The specimens were aged (10,000 thermal cycles and water storage for 90 days) prior to shear bond test. Failure types were analyzed under stereomicroscope and SEM, and phase transformation was calculated. Data (MPa) were analyzed using 3-way ANOVA and Tukey’s tests. Air-abrasion with 110 μm silica particles (10.96) presented significantly higher bond strength (p = 0.0149) compared to 30 μm (8.96). Time (p = 0.403) and distance (p = 0.179) parameters did not affect the results significantly. Air-abrasion with 110 μm particles (12.3) promoted higher bond strength than that of 30 μm (6.4) when applied for 10 s from a distance of 10 mm (Tukey’s). Failure types were predominantly adhesive. Phase transformation ranged between 30.3 and 35.9% for 30 μm particles and 23.8–43.7% for 110 μm particles. While the size of silica-coated alumina particles were more relevant parameter for resin cement adhesion to Y-TZP, time (up to 20 s) and distance (up to 20 mm) appear to be less pertinent.     

Effect of mechanical and air-particle cleansing protocols of provisional cement on immediate dentin sealing layer and subsequent adhesion of resin composite cement

Immediate dentin sealing (IDS) could avoid contamination of dentin from impression material and provisional cement but prior to final cementation of indirect restorations, removal of the provisional cement may damage the IDS. The objectives of this study were to investigate the effect of mechanical and air-particle cleansing protocols of provisional cement on IDS layer and subsequent adhesion of resin composite cement. The cuspal dentin surfaces of human third molars (N = 21, n_quadrant = 84) were exposed by a low-speed diamond saw under water cooling and conditioned with an adhesive system based on the three-step etch and rinse technique (OptiBond FL). Provisional cement (Freegenol) was applied on each specimen. They were then randomly divided into six subgroups where the provisional cement was removed either by (1) air-borne particle abrasion with 50-μm Al₂O₃ particles at 2 bar (AL2), (2) air-borne particle abrasion with 50-μm Al₂O₃ particles at 3.5 bar (AL3.5), (3) air-borne particle abrasion with 30-μm SiO₂ particles at 2 bar (SL2), (4) air-borne particle abrasion with 30-μm SiO₂ particles at 3.5 bar (SL3.5), (5) prophylaxy paste (Cleanic) (PP) or (6) pumice-water slurry (PW) at 1500 rpm for 15 s. The dentin surface on each tooth was assigned to four quadrants and each quadrant received the cleansing methods in a clockwise sequence. The non-contaminated and non-cleansed teeth acted as the control (C). Two separate teeth, contaminated and cleansed according to six cleansing protocols, were allocated for scanning electron microscopy (SEM) analysis (×2000). The dentin surfaces in each quadrant received resin composite luting cement (Variolink II, Ivoclar Vivadent) incrementally in a polyethylene mould (diameter: 1 mm²; height: 4 mm) and photopolymerized. The specimens were stored in distilled water for 24 h at 37 °C until the testing procedures and then shear force was applied to the adhesive interface until failure occurred in a universal testing machine (0.5 mm/min). Microshear bond (μSBS) was calculated by dividing the maximum load (N) by the bonding surface area of the resin cement. Failure types were analysed using optical microscope and SEM. Data (MPa) were analysed using one-way ANOVA (α = 0.05). Two-parameter Weibull distribution values including the Weibull modulus, scale (m) and shape (₀), values were calculated. Mean μSBS results (MPa) showed a significant difference between the experimental groups (p = 0.011) and were in a descending order as follows: C (8 ± 2.3)^a < AL2 (6.7 ± 2.4)^b < PP (6.9 ± 2)^b < PW (6.5 ± 2.1)^b < AL3.5 (5.8 ± 1.1)^b < SL2 (5.3 ± 1)^b < SL3.5 (5.2 ± 1)^b. Failure types were predominantly mixed failure type between the dentin and the adhesive resin which is a combination of adhesive and cohesive failures in the adhesive resin. Cohesive failure in the dentin was not observed in any of the groups. Weibull distribution presented lower shape (₀) for C (3.9), AL2 (3.2), PP (3.5) and PW (3.6). SEM analysis showed rough surfaces especially in the air-abraded groups whereas mechanical cleansing methods presented smoother surfaces and partially covered by particle remnants all of which occluded the dentin tubuli.     

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.     

Effects of chemical and physico-chemical surface conditioning methods on the adhesion of resin composite to different mineral trioxide aggregate based cements

This study investigated the adhesion of resin composite to mineral trioxide aggregate based cements after different chemical and physico-chemical surface conditioning methods. Mineral trioxide aggregate based cements (Biodentine, ProRoot MTA, Imicryl MTA) were embedded in Teflon disks (N?=?180). After storing at 37?°C at 100% humidity for 72?h, substrate surfaces were polished using silicon carbide papers. Specimens were allocated to 3 groups to be conditioned with one of the following (n?=?15 per group): a) Adhesive resin (Clearfil SE Bond, CSE), b) Adhesive resin (Adper Single Bond 2, SB2), c) air-abrasion with 30?μm alumina coated with silica?+?silane?+?adhesive resin (ALB), d) no surface conditioning, control group (CON). Microhybrid resin composite (Filtek Z250) was applied on the conditioned substrate surfaces and photo-polymerized. After storage at 37?°C at 100% humidity for 24?h, adhesive interfaces were loaded under shear (1?mm/min) in a universal testing machine. After debonding failure types were analyzed. Data were analyzed using 2-way ANOVA and Tukey’s test (alpha = 0.05). SBS results were significantly affected by surface conditioning (p?<?0.05) and materials (p?<?0.05). Interaction terms were significant (p?<?0.05). Biodentine-ALB resulted in significantly higher SBS values (3.96?±?1.24) compared to those of other combinations, while ALB and SB2 resulted in no significant difference for ProRoot MTA and Imicryl MTA (p?>?.05). CSE (1.36?±?0.5- 1.98?±?0.76) did not significantly increase SBS for all MTA materials compared to the control group (0.8?±?0.52 – 2?±?0.91) (p?>?9.05). While CON groups resulted in exclusively adhesive failures, ALB presented the highest incidence of mixed failures for all materials tested (60–100%).     

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.     

Could readily silanized silica particles substitute silica coating and silanization in conditioning zirconium dioxide for resin adhesion?

This study investigated the effect of particle types with different morphology and surface properties on the wettability and adhesion of resin cement to zirconia. Zirconia specimens (5 × 5 × 1 mm³) were wet polished. Specimens were randomly assigned to one of the following protocols (N = 36, n = 9 per group): Group CON: Control, no surface conditioning; Group AL: Chairside air-abrasion with aluminium trioxide (50 μm Al₂O₃) + silane; Group SIL: Chairside air-abrasion with alumina particles coated with silica (SIL) (30 μm SiO2, SilJet) + air-drying + silane; Group 4: Chairside air-abrasion with readily silanized silica particles (SILP) (30 μm SiO_2, SilJet Plus). Adhesive resin was applied and resin cement (Variolink II, Ivoclar) was bonded using polyethylene moulds and photo-polymerized and aged (thermocycling, 6.000 cycles, 5–55 °C). Shear bond test was performed using Universal Testing Machine (1 mm/min). Pretest failures were considered 0 MPa. Contact angle measurements were performed (n = 2/group, sessile drop with water). Data (MPa) were analyzed (ANOVA, Tukey’s (α = 0.05). Two-parameter Weibull distribution values including the Weibull modulus, scale (m) and shape (0), values were calculated. Contact angle measurements were in descending order as follows: SIL (74°)^c < CON (60°)^c < AL (51°)^b < SILP (40°)^a. Bond strength (MPa) with SIL (17.2 ± 4)^a and SILP (17.3 ± 1.9)^a demonstrated no significant difference (p > 0.05), being higher than AL (8.4 ± 1.5)^b and CON (0)^c (p < 0.05). Failure types were exclusively adhesive in all groups. Weibull distribution presented the highest shape (0) for SILP (10.8). SILP presented better wettability than AL. SILP provided similar bond strength to SIL. Readily silanized silica particles may substitute for conventional silica coating and silanization.     

Effect of different air-abrasion protocols on topography,surface wettability and adhesion of MDP monomer-based resin cement to zirconia

This study evaluated the effect of air-abrasion protocols on the topography, surface wettability and adhesion of resin cement to zirconia. Ceramic specimens (N?=?49; n?=?7) (15?mm × 2?mm) were randomly allocated to seven groups to be treated with: (1) Air-abrasion with 45?μm Al₂O₃ (A45), (2) 80?μm Al₂O₃ (A80), (3) 30?μm Al₂O₃ coated with SiO₂ (CoJet) (C30), (4) 30?μm Al₂O₃ coated with SiO₂ (Rocatec Soft) (R30), (5) 110?μm Al₂O₃ coated with SiO₂ (Rocatec Plus) (R110); (6) R110R30 (Rocatec) (R110R30) and (7) control, no conditioning (NC). Air-abrasion was performed using a chairside air-abrasion device (2.5?bar, 10?mm, 90?s). Contact angle measurements were performed using goniometry (n?=?5). MDP-based dual resin cement (Panavia F2.0) was bonded on four locations after air-abrasion protocols (n?=?20 per group). Half of the specimens were tested after 24?h and the other half after thermal cycling (×3000, 5–55?°C). Data were analyzed using 1-, 2-way ANOVA and Tukey’s test (alpha = 0.05). Significantly lower contact angle values were observed for groups C30 (62.6?±?0.91), R30 (61.91?±?1.05) and R110R30 (61.54?±?1.02) compared to those of other groups (65.5?±?0.9–110.61?±?0.9) (p?<?0.05). In dry conditions, surface conditioning methods tested did not show significant effect on bond strength (MPa) (10.57?±?1.42–16.86?±?2.54) (p?=?0.238). After thermocycling, bond strength results decreased significantly (p?<?0.05) (12.6–51.2%). R110 (7.18?±?1.34) and A80 (4.92?±?1.53) showed significantly higher bond strength compared to other groups (2.13?±?0.73–4.16?±?1.34) (p?<?0.05). The best wettability and adhesion results with MDP-based resin cement to zirconia was achieved with A80 and R110 air-abrasion.