Effect of surface conditioning methods,adhesive systems and resin composite on repair strength of dimethacrylate and silorane resin composites

This study evaluated the effect of surface conditioning methods and adhesive systems on the repair bond strength of resin composites. Specimens (FLS: Filtek LS) (N = 144) were prepared using a silicone matrix. The specimens were stored in distilled water and then were randomly divided into the twelve groups (n = 12) according to the surface conditioning method (unground or diamond bur) and adhesive system (no adhesive, LS: Filtek LS, AS: Adper Scotchbond SE Plus) and resin composite (FLS: Filtek LS; FS: Filtek Supreme). The specimens were fixed in an hourglass-shaped silicone matrix and the other half of the specimen was restored. Hourglass-shaped specimens (n = 12) were used as positive control to measure the cohesive strength of the resin composite (Filtek LS). Microtensile bond test was performed (0.5 mm/min) and failure types were analyzed. Data were analyzed using two-way analysis of variance, Tukey’s and Dunnett’s tests (α = 0.05). Adhesive protocol and resin composite significantly affected the results (p < 0.05). For the FS composite, the highest results were obtained using LS adhesive with (18.4 ± 7.7) and without (18.8 ± 4.8) bur roughening. For FLS composite, the highest results were obtained using AS adhesive with (33.2 ± 7.1) and without (25.7 ± 3.6) bur roughening. Without the use of adhesive resin, significantly lower bond strength results were observed with both LS (5 ± 2.1, 4.5 ± 1.5) and FLS (2.2 ± 1.2, 4.4 ± 1.1) for unground and diamond bur roughened groups, respectively (p < 0.0001). Cohesive strength of the FLS (52.3 ± 7.6) was significantly higher than any of the repaired groups (p < 0.0001). FS–LS combination and the groups repaired without adhesive presented more adhesive (Type I) failures.     

Effect of aging type and aged unit on the repair strength of resin composite to feldspathic porcelain in testing microtensile bond strength

The aim of the present study is to investigate the effect of aging type (thermocycling vs. water storage) and aged unit (block vs. stick) on the repair strength of resin composite to feldspathic porcelain in testing microtensile bond strength (μTBS). Ceramic specimens (N = 30) (10 × 5.7 × 4.5 mm³, Vita Mark II, Vita) were obtained from CAD–CAM blocks. One surface was etched with 10% HF and silanized. An adhesive was applied and resin composite blocks were constructed incrementally on the conditioned surface. The specimens were randomly divided into five groups (n = 6): Control (C): Non-aged; BTC: Blocks were thermocycled (5–55 °C, 6000 cycles); STC: Sticks were thermocycled; BS: Blocks aged in water storage (6 months) after themocycling; SS: Blocks aged in water storage (6 months) after thermocycling. After μTBS test, failure types were classified. Data (MPa) were statistically analyzed (1-way and Dunett and 2-way ANOVA, Tukey`s) (α = 0.05). Two-parameter Weibull distribution values including the Weibull modulus, scale (m), and shape (0) values were calculated. Aging type (p = 0.009) and aged unit (p = 0.000) significantly affected the results. Interaction terms were also significant (p = 0.000). Considering the stick level, there was no significant difference between thermocycling (STC: 25.7 ± 2.3) and water storage (SS: 25.3 ± 3.8) (p > 0.05) but the results were significantly higher when blocks were thermocycled (BTC: 31.6 ± 2.9) (p < 0.05). Weibull modulus and characteristic strength was the highest in BTC (m = 4.2; σ_o: 34.4) among all other groups (m = 3–3.9; σ_o: 14.6–28.5). Adhesive failures were common and cohesive failures occurred in less than 5% in all groups. Aging protocol was detrimental on durability of repair strength of resin composite to feldspathic porcelain. Exposing the sticks to either thermocycling or water storage aging should be considered in in vitro studies.     

Adhesion of conventional and self-adhesive resin cements to indirect resin composite using different surface conditioning methods

This study evaluated the adhesion of conventional and self-adhesive resin cements to indirect resin composite (IRC) using different surface conditioning methods. Cylindrical IRC specimens (N = 192) were randomly assigned to four surface conditioning methods (n = 8 per group): (a) Control group, (b) Hydrofluoric acid, (c) Tribochemical silica-coating, and (d) 50 μm Al₂O₃ air-abrasion. Specimen surfaces were finished using silicon carbide papers up to 600 grit under water irrigation, rinsed and dried. Direct composite blocks were bonded to IRC specimens using three conventional resin cements (Multilink, Panavia F2.0, and Resicem) and three self-adhesive resin cements (RelyX U100, Gcem, Speed Cem). Specimens were subjected to shear bond strength test in a Universal Testing Machine (0.5 mm/min). Failure types were categorized as mixed, adhesive and cohesive. Data were analyzed using 2-way ANOVA and Tukey’s tests. Two-parameter Weibull modulus, scale (m) and shape (0) were calculated. The bond strength results (MPa) were significantly affected by the surface conditioning method (p < 0.0001) and cement type (p < 0.001). For Panavia F2.0, Resicem, air-abrasion with 50 μm Al₂O₃ significantly increased the results (22.6 ± 6.5, 26.2 ± 6.5, respectively) compared to other conditioning methods (13.6 ± 1.4–21.9 ± 3.1) but for Multilink, hydrofluoric acid etching (20.5 ± 3.5) showed significantly higher results (p < 0.01). For the self-adhesive resin cements, air-abrasion with 50 μm Al₂O₃ significantly increased the results compared to other conditioning methods, except for RelyX U100 (p < 0.05). After air-abrasion with Al₂O₃, Gcem, (11.64), RelyX U100 (9.05), and SpeedCem (8.29) presented higher Weilbul moduli. Exclusively cohesive failure in the IRC was observed with RelyX U100 and Speedcem after Al₂O₃ air-abrasion.     

Effect of different adhesive protocols on bond strength between composite resins for indirect use and repair materials

Abstract

The aim of this work is to evaluate the effect of different adhesive protocols on the bond strength (SBS) of composite resin for indirect use to repairs of bulk-fill or conventional nanoparticulated composites. Forty-eight cylindrical specimens of composite resin for indirect use were prepared, aged, and randomly divided into four groups (n?=?12), a control group without any adhesion protocol, and three experimental groups: Silane?+?Scotch Bond Multipurpose adhesive (S?+?SBMP), Tetric N Bond Universal (TBU), and Single Bond Universal (SBU). The treated surfaces were restored using two different composite resins: Filtek Bulk-Fill or Filtek Z350XT. Then, the specimens were submitted to the SBS test, and the resultant data were analyzed with ANOVA on ranks test and Tukey’s test (α?=?0.05). There were no significant differences between the two types of resins used as repair material. For both resins, the groups treated with S?+?SBMP obtained the highest values (p?<?0.001). Groups TBU and SBU did not have statistically significant differences between them. Pre-treatment with a silane coupling agent and a layer of a hydrophobic adhesive can improve the bond strength of repairs performed on a composite resin for indirect use.     

Adhesion of orthodontic brackets to indirect laboratory-processed resin composite as a function of surface conditioning methods and artificial aging

This study compared the shear bond strength of orthodontic brackets to laboratory-processed indirect resin composites (IRC) after different surface conditioning methods and aging. Specimens made of IRC (Gradia Indirect, GC) (thickness: 2 mm; diameter: 10 mm) (N = 80) were randomly assigned to one of the following surface conditioning methods: C – Control: no treatment; AA – Air-abrasion (50 μm Al₂O₃ particles); DB – Diamond bur and HF – Etching with hydrofluoric acid (9.6%). After adhesive primer application (Transbond XT), orthodontic brackets were bonded to the conditioned IRC specimens using adhesive resin (Transbond XT). Following storage in artificial saliva for 24 h at 37 °C, the specimens were thermocycled (×1000, 5–55 °C). The IRC–bracket interface was loaded under shear in a Universal Testing Machine (0.5 mm/min). Failure types were classified using modified adhesive remnant index criteria. Data were analyzed using two-way ANOVA and Tukey`s HSD (α = 0.05). Surface conditioning method did not significantly affect the bond strength results (p = 0.2020), but aging significantly decreased the results (p = 0.04). Interaction terms were not significant (p = 0.775). In both non-aged and aged conditions, non-conditioned C group presented the lowest bond strength results (MPa) (p < 0.05). In non-aged conditions, surface conditioning with DB (8.03 ± 0.77) and HF (7.87 ± 0.64) showed significantly higher bond strength results compared to those of other groups (p < 0.05). Thermocycling significantly decreased the mean bond strength in all groups (2.24 ± 0.36–6.21 ± 0.59) (p < 0.05). The incidence of Score 5 (all adhesive resin remaining on the specimen) was the highest in HF group without (80%) and with aging (80%) followed by DB (40, 70%, respectively). C groups without and with aging showed exclusively Score 1 type (no adhesive resin on the specimen) of failures indicating the least reliable type of adhesion.     

Effect of ceramic surface treatments on the bond strength of different composite resins

This study was aimed to observe the relationship between the different surface treatments and the bond strength of both composite based adhesive cement and zirconia ceramic. Thirty-two zirconia ceramic discs were fabricated by following the instructions of manufacturer (5 × 5 × 1.5 mm). Four subgroups were obtained from the specimens according to the specified surface treatments respectively: (a) C: control groups: no treatment; (b) SB: sandblasting with 125 μm aluminum oxide particles for 10 s; (c) SC: silica coating for 10 s; (d) Nd :YAG laser . The composite resin specimens Panavia F and Clearfil SA were introduced and polymerized to the treated bonding areas. Afterwards the specimens were stored in distilled water at 37 °C during 24 h, and the shear test was applied. The data were statistically analyzed by ANOVA and Duncan tests. The bond strength was stated significantly higher in silica coating/Panavia F group (23.35 MPa). The lowest bond strength was stated in control groups cemented with Clearfil SA (12.25 MPa). As a result it was determined that the bond strength has affected the both surface treatments and cement types (p < 0.001). The silica coating –treated zirconia ceramic recorded a significant increase in mean bond strength values.     

Immediate and delayed repair bond strength of a new ormocer resin restorative material as a function of mechanical and chemical surface conditioning methods

This study evaluated the μ-shear repair bond strength (μSBS) of a new ormocer restorative material as a function of repair time and repair protocol. Ormocer disks (N = 140) (Admira Fusion, Voco) were prepared and divided into 14 groups: Factor 1: Bonding protocol (No Conditioning, Admira Bond, Futurabond M+, Silane/Admira bond, Silane/Futurabond M+, Ceramic repair system, Silane/Cimara bond) and Factor 2: Repair procedure time (immediate versus delayed). Each disk received two ormocer micro-cylinders. Half of the disks were repaired immediately (24 h) and the other half after six-month water storage. Shear test was run at cross-head speed of 0.5 mm/min. Debonded specimens were evaluated for failure mode and SEM analysis was performed. Data were analyzed using two-way ANOVA and Tukey’s tests (p < 0.05). Both the repair time and the surface conditioning method showed a significant effect on the repair μSBS (MPa) of the ormocer material (p = 0.000). When immediate repair strengths were considered, all repair protocols tested reached the mean bond achieved based on oxygen-inhibited layer (10.8 ± 2.4 MPa), except. Futurabond M+(13.9 ± 3.4) and Silane/Cimara adhesives (16.3 ± 2.9) showed significantly higher μSBS (p = 0.001 and p = 0.000, respectively). For the delayed repair, non-conditioned (5 ± 1.7), showed significantly lower values compared to those of the other protocols (p < 0.05). Failure modes were predominantly adhesive type (immediate:95% and delayed:90%). No cohesive failures were observed either in the substrate or in the repair material.     

Effect of clinical and laboratory contamination media on the adhesion of luting cement to direct and indirect resin composite materials

This study evaluated the effect of contamination media on the adhesion of resin cement to resin composites. Specimens of direct (DRC) (Quadrant Photo Posterior) and indirect resin composite (IRC) (Gradia) (N = 300, n = 15 per group) were prepared. Except the control group (C), the specimens of DRC and IRC were contaminated with one of the following media: (a) saliva (S), (b) silicon (SI), (c) dental stone (D), and (d) isolation medium (I). While one half was only rinsed with water, the other half was silica coated (30 μm SiO₂, Siljet). All specimens were silanized (Monobond Plus) and coated with adhesive resin (Heliobond). Resin cement (Variolink II) was bonded to the substrates and photo-polymerized for 40 s. After thermocycling (x5.000, 5–55 °C), composite–cement interface was loaded under shear in a Universal Testing Machine (1 mm/min). Data (MPa) were analyzed using Univariate analysis, Tukey’s and Dunnett-T3 tests. Both contamination media (p = 0.000) and surface conditioning (p = 0.005) significantly affected adhesion to DRC and IRC. No significant difference was found between the DRC and IRC (without: p = 0.098; with: p = 0.084). Significantly lower results were obtained after SI (DRC: 0.66 ± 0.6; IRC: 0.8 ± 1.3) followed by I contamination (DRC: 2.1 ± 2.6; IRC: 0.8 ± 1.3) (p < 0.05). Regardless of contamination medium, surface conditioning significantly increased the results for both DRC (15.1 ± 6.1–23.6 ± 3.7) and IRC (20.3 ± 5.4–25.1 ± 3.6) (p < 0.05). Weibull distribution increased after surface conditioning for both DRC (without: 1.33–3.27; with: 2.55–9.34) and IRC (without: 1.07–3.75; with: 3.7–7.73). Predominantly adhesive (132 out of 150) failures were observed when surfaces were not conditioned.     

Effect of 2% chlorhexidine gluconate cavity disinfectant on microtensile bond strength of tooth-coloured restorative materials to sound and caries-affected dentin

This study evaluated the effect of 2% chlorhexidine gluconate-based cavity disinfectant (CHX) on the microtensile bond strength (μTBS) of glass ionomer, resin-modified glass ionomer and packable resin composite to sound and caries-affected dentin. Sound and occlusal caries-affected human third molars (N?=?36, n?=?3 per group) were randomly divided into three experimental groups to receive one of the following restorative materials. (a) Glass ionomer (Ketac Molar, 3 M ESPE; GI), (b) resin-modified glass ionomer (Vitremer, 3 M ESPE; RMGI) and (c) packable resin composite (Surefil, Dentsply; PRC) with a bonding agent (Prime Bond NT, Dentsply De Trey). Caries was removed using a caries-detecting dye (Caries Detector, Kuraray Medical Ltd.) and flat dentin surfaces were achieved by finishing up to 1200-grit silicon carbide abrasive. Half of the teeth in each group received 2% CHX (Consepsis, Ultradent). Dentin surfaces were built-up with the respective materials incrementally and were sectioned with a slow-speed saw into multiple beams. The beams were subjected to μTBS test (0.5 mm/min) in a Universal Testing Machine. The data were analysed using two-way analysis of variance and Tukey’s tests. For each restorative material, μTBS results were not affected by the application of CHX (p?>?0.05) on both sound and caries-affected dentin (p?>?0.05). PRC in combination with the corresponding bonding agent showed significantly higher results (p?<?0.05) than those of GI and RMGI, on sound and caries-affected teeth, respectively. Cohesive failure in dentin was not observed in any of the groups. The use of 2% chlorhexidine-based cavity disinfectant did not impair the adhesion of the restorative materials tested to either sound or caries-affected dentin.     

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.     

Effect of different surface treatments on the repair bond strength of resin composites with titanium

The purpose of this study was to evaluate the effect of different surface treatment combinations on the bonding of composite resins to NiCr and titanium alloys after thermal cycling. Square-shaped specimens (10?mm x 10?mm x 2?mm) were made from NiCr and titanium alloys. The specimens were divided into 6 pretreatment groups (n?=?11): (1) machined titanium (control, no treatment); (2) CoJet sand application; (3) grinding with a diamond bur; (4) metal primer application; (5) CoJet sand?+?metal primer application; and (6) grinding with a diamond bur?+?metal primer application. The surface roughness of the mechanically treated specimens (control, grinding, CoJet sand) was evaluated. The surface morphology of both metals and elemental composition were examined with SEM and EDS. The composite resin was applied to the specimens. Shear bond strength (SBS) was tested after thermal cycling (5000 cycles, 5?°C to 55?°C). Failure modes were determined. The data were analyzed using the Shapiro-Wilk test, two-way ANOVA and post hoc Fisher’s LSD test (p?=?.05). For titanium specimens, the grinding?+?metal primer exhibited higher values than the other groups, and all groups showed higher SBS values than the control group. Combined use of CoJet sand, grinding with a diamond bur, and metal primer application would be useful for enhancing the bond strength of composite resin to titanium. The grinding of the NiCr surface with a diamond bur is the only method that could improve the bond strength of a composite resin compared to the other methods.     

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.     

Efficacy of different surface treatments and universal adhesives on the microtensile bond strength of bulk-fill composite repair

Abstract

The purpose of this in vitro study was to evaluate the influence of different surface treatments and aging on the microtensile bond strength (μTBS) of bulk-fill composite resins. Bulk-fill composites (Filtek One; 3M ESPE) randomly received five different surface treatments: (1) no treatment, control, (2) 37% phosphoric acid etching (PA), (3) 9% hydrofluoric acid etching (HF), (4) air-borne particle abrasion with 50-μm alumina particles (Al₂O₃), (5) tribochemical silica coating (CoJet). Following, the specimens were divided into three subgroups according to universal adhesive applied: Clearfil Universal Bond (CU; Kuraray), Prime&Bond Universal (PBU; Dentsply Sirona), or Single Bond Universal (SBU; 3M ESPE). A nanofill composite (Filtek Ultimate; 3M ESPE) was employed as a repair. Bonded specimens were stored in water for 24?h at 37?°C or thermal aged, then subjected to the μTBS test. Additionally, specimens were analyzed with a contact profilometer and were evaluated with scanning electron microscopy. Control and PA treatments were showed the lowest µTBS (p?<?0.05), and there was no significant difference between these two groups (p?>?0.05). Al₂O₃ and CoJet treatments generally exhibited a similar influence on µTBS values. In addition, a correlation was found between surface roughness and bond strength (r?=?0.831). CoJet resulted in significantly higher repair µTBS values when compared to the other surface treatments. In addition, the use of silane-containing universal adhesive was increased the cohesive failure rate and maintained the repair µTBS values after thermocycling.     

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.     

Effect of self-etching ceramic primer on the bond strength of feldspathic porcelain repair

The purpose of this study was to evaluate the effect of a self-etching primer on the bond strength of feldspathic porcelain with composite resin. Forty-eight feldspathic porcelain specimens (13 mm × 13 mm × 2 mm) were sectioned from CAD/CAM blocks. Specimens were randomly divided into 4 groups (n = 12) as regards to surface treatment method; HF acid etching (HFE), Monobond Etch and Prime (MEP), sandblasting (SB), and MEP + SB. After silane application for group HFE and SB, an adhesive bond was used as a bonding agent in all groups. Composite resin cylinders were build up onto the specimens. Specimens were stored in distilled water, thermocycled 5–55 °C for 5500 cycles, and subjected to shear bond strength (SBS) test in a universal testing machine. Data were statistically analyzed by Kruskal-Wallis and Mann Whitney U test (α=.05). Type of failures was evaluated under optical microscopy and surfaces were examined by SEM at ×500 and ×2500 magnifications. There was a significant difference among groups. (p = .019) HF group had the highest mean SBS value (17.54 ± 2.98 MPa) which was significantly higher than other groups (p<.05). Followed by the MEP + SB group (14.68 ± 3.41 MPa), SB group (13.98 ± 3.34 MPa) and MEP group (12.75 ± 2.33 MPa). Nevertheless, the HFE group significantly has higher SBS value than other groups all of the tested surface treatment methods have reached the convenient bond strength values for repair. Although MEP showed clinically acceptable SBS values, further researches with another type of porcelains should be tested.     

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.     

Microtensile bond strength of composite-to-composite repair with different surface treatments and adhesive systems

Objectives: The purpose was to investigate the effect of different surface treatments and bonding agents on the repair bond strength of different resin-based restorative materials by microtensile bond strength (μTBS) testing protocol. Materials and Methods: 24 Grandio SO(VOCO) and 24 Filtek Z250(3?M) resin composite blocks were prepared. Half of the samples (N?=?12) were diamond bur-roughened and the other half (N?=?12) were sandblasted by 50?μm aluminum oxide particles. They were further divided into four sub-groups (n?=?3) and received the following: Sub-Group1: Adper Single Bond2 (Etch&Rinse) (3?M); Sub-Group2: Clearfil SE (Self-etch) (Kuraray); Sub-Group3: Beauty Bond (HEMA-free all-in-one) (Shofu); Sub-Group4: All Bond3 (HEMA-free, hydrophobic, etch&rinse) (Bisco). The samples were repaired by Filtek Z250 to form a block. All of the resultant sub-groups combinations consisted of one of the composite type, surface treatment type, and adhesive systems. A total of 18 groups were prepared including 2 homogeneous blocks. They were thermocycled and μTBS measurements were performed. Data were statistically analyzed with Kruskall–Wallis and Mann–Whitney U tests. Results: The experimental regroups’ μTBS reached to 34.67–66.36% and 43.44–95.52% of the cohesive bond strength for Grandio SO and Z250, respectively. The pre-existing composite type is found to be statistically important. When the surface is bur-finished Grandio performed better; when air-abrasion is considered Z250 showed higher bond strength. All-in-one adhesive system produced the weakest bond strength at all parameters. Conclusion: It may be suggested that when the pre-existing composite is unknown, air-abrasion may be performed with etch&rinse or two-step self-etch adhesives.     

Effect of different ceramic primers on shear bond strength of resin-modified glass ionomer cement to zirconia

Purpose: This study evaluated and compared the effect of different ceramic primers on the shear bond strength of RMGIC to zirconia with and without air-particle abrasion. Material and Methods: 120 zirconia square specimens (5 mm × 5 mm × 2 mm) were fabricated. Half of the specimens were air-particle abraded (A) and the other half were left untreated (NA). Both groups were further divided into six subgroups (n = 10). Composite cylinders (2.9 mm × 3.0 mm) were fabricated and bonded to the zirconia samples with RMGIC (RelyX Plus) after different priming methods: no ceramic primer (group NS); Z-Prime (group ZP); Clearfil ceramic primer (group CP); cleaned with Ivoclean then Monobond plus (IV/MS); Monobond plus (group MS); and Rely X ceramic primer (group RX). Specimens were rinsed, stored in distilled water, and thermocycled (TC) for 10,000 cycles between 5 and 60 °C with a dwell time of 15s. Data were analyzed with two-way ANOVA and the Tukey–Kramer method test (a = .05). Results: air-particle abrasion significantly affected bond strength of RMGIC to zirconia regardless of the primer used (p < 0.001 for all primers and the control). After TC, A-ZP (11.1 ± 0.6 MPa), A-CP (11.9 ± 0.6 MPa), and A-MS (11.9 ± 0.5 MPa) revealed the highest shear bond strength values, while NA-NS (2.9 ± 0.3 MPa) and NA-RX (4.7 ± 0.5 MPa) had the lowest. Failure modes were primarily adhesive. Conclusion: air-particle abrasion with aluminum oxide and application of MDP-based ceramic primers provide the highest bond strength of RMGIC to zirconia.     

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.     

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.