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.     

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.     

Long-term bond strength of fiber posts cement to dentin with self-adhesive or conventional resin cements

The aim of this study was to evaluate the immediate and the long-term push-out bond strength of glass fiber posts (GFP) cemented with conventional or self-adhesive dual-curing resin cements, at different root depths. Prior to cementation, the GFP (Reforpost #3, Angelus) were etched with 37% phosphoric acid for 30 s followed by silane for 1 min. Thirty canine roots were divided into two groups (n = 15) according to resin cement type: ARC – dual resin cement (RelyX ARC/3M ESPE) combined with an three-step etch-and-rinse adhesive (Adper Scotch Bond Multi-Purpose Plus 3M/ESPE) or U200 – self-adhesive resin cement (RelyX U200/3M ESPE). The manufacturer’s instructions were followed. After 48 h, the roots were cross-sectioned at three different depths, resulting in serial slices corresponding to the cervical, middle, and apical root thirds. Slices were randomly divided into two groups, according to the period of water storage prior to push-out bond strength analysis: 48 h or 180 days. The data (MPa) were analyzed using three-way ANOVA for randomized blocks (p < 0.05), which showed no significant interaction between the three factors (p = 0.716). The main study factors were also proven not significant (cement: p = 0.711; time: 0.288; root third: p = 0.646). In conclusion, root depth, cement type (self-adhesive or conventional), and storage in water for 180 days did not influence the bond strength of GFP to intracanal dentin.     

Influence of desensitizing procedures on adhesion of resin cements to dentin

This study evaluated the effect of two desensitizer agents with different contents and Nd:YAG laser irradiation on the shear bond strength (SBS) of adhesive resin cements to dentin. New treatment options of Nd:YAG laser irradiation and tetracalcium phosphate-containing agent applications were compared with routinely used glutaraldehyde-containing agents. One hundred and twenty human, caries-free premolars were embedded in acrylic resin blocks 2 mm below the cementoenamel junction. Buccal surfaces of the teeth were ground to expose dentin. The specimens were randomly assigned into three different surface treatments (desensitizing agents, Nd:YAG laser) and the control, then into three different adhesive resin cement applications (n = 10). Resin cements (Panavia SA cement (PA), Panavia SA cement with Clearfil Universal Bond (PACU), and Multilink N (MN)) were applied to the conditioned teeth surfaces using Teflon tubes. The specimens were thermocycled (5000 cycles, 5–55 ± 1 °C, dwell time 30 s). The SBS test was performed in all groups. The results were submitted to two-way ANOVA and Tukey HSD tests (p < .05). Further, SEM analysis was performed on the dentin surfaces. SBS values were significantly difference among the surface treatment groups and also among adhesive resin cement groups (p < .05). The specimen cemented with PA showed lower SBS values than PACU- and MN-applied specimens. The highest SBS value was obtained in the Nd:YAG laser group which was cemented with PACU cement. The lowest SBS value was obtained in the control group which was cemented with PA cement. In addition, SEM evaluation revealed that desensitizing agents and Nd:YAG laser occluded dentin tubules.     

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

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

Bonding ability of self-adhesive resin-cements after dentin biomodification with hyaluronic acid

Purpose: The present study evaluated the influence of the hyaluronic acid (HA) on the bonding ability of self-adhesive resin cements to dentin regarding the bond strength. Eighty bovine incisors were ground flat to obtain a 2-mm thick slices which received conical preparations. The specimens were randomly distributed into 4 groups (n = 15) according to the dentin pretreatment (1 – control: untreated dentin; 2 – application of HA) and the evaluation time (1 – control: immediate evaluation; 2 – hydrolytic degradation: 6 months of storage in water at 37 °C). Preparations received the application of a self-adhesive resin cement (RelyX U200 or MaxCem Elite). Push-out bond strength test was conducted (0.5 mm/min). The bond strength data was submitted to two-way ANOVA/Tukey’s test (α = 0.05). For U200, no significance was observed when comparing the immediate (24 h) and 6 months means for the control groups (unexposed specimens). Previous application of HA to dentin significantly reduced the bond strength of U200 to dentin in both evaluation times (p < 0.05). HA had no significant influence on the push-out bond strength means for the cement MAX in both evaluation times (p > 0.05). The type 1 failure mode (adhesive mode) occurred in 100% of the specimens, irrespective of the dentin treatment or evaluation times. Pretreatment of dentin with HA produces a material-dependent influence on the push-out bond strength. The bonding ability of RelyX U200 is negatively influenced by the pretreatment of dentin with HA, whereas the biomodification of dentin with this bioactive agent causes no impact for the cement MaxCem Elite.     

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 cyclic loading and resin cement type used for luting fiber posts on bond strength at different root levels of crown-restored human teeth

Objective: This study aimed to evaluate the bond strength (BS) of glass fiber posts (GFP) at different root levels when luted with conventional or self-adhesive cements in crown-restored human premolars subjected, or not, to cyclic mechanical loading.

Materials and Methods: Sixty lower premolar roots were endodontically treated and prepared for a GFP system. Half of the roots (n = 30) had their posts cemented with a self-adhesive resin cement, while the remaining roots followed a three-step conditioning method: acid etch, bonding agent, and a conventional resin cement. Metal crowns were luted onto the post-core preparations and the specimens were embedded to simulate the periodontium. Half of the specimens from each group (n = 15) were submitted to cyclic loading simulations (130 N; 2.0 Hz) and then sections were obtained from each root for the pushout BS test.

Results: Independently of the cyclic loading and the root level tested, the conventional resin cement provided significantly higher values of BS (p = 0.002). For either cement or either root level, cyclic loading caused a significant decrease in BS values (p = 0.023). The Tukey test indicated that, regardless of the resin cement used or the cyclic loading, BS was highest at the middle and cervical thirds of the root (p = 0.026), and their values did not differ between themselves.

Conclusions: When used for luting GFP, self-adhesive resin cement resulted in lower pushout BS than the conventional counterpart, with cyclic loading causing a decrease in BS of the GFP to dentin for both resin cements.     

Endodontic irrigants effect on long-term intraradicular adhesion of resin cements

The aim of this study was to evaluate over time the bond strength of dual-cure and self-adhesive resin cements used for bonding fiberglass posts following irrigation with different solutions. Ninety roots from single-rooted premolars were selected and divided into 6 groups (n = 15) according to the resin cement, dual-cure or self-adhesive (RelyX ARC and RelyX U100) or the endodontic irrigant used (2% chlorhexidine digluconate - CH, 1% sodium hypochlorite - SH and deionized distilled water – control). Following post cementation, the roots were cross-sectioned in order to obtain two slices from each root third (cervical, mid and apical). The specimens were stored for 7 or 180 days in water and the push-out bond strength test applied. The data was analyzed using three-way ANOVA and Tukey Kramer. The interaction endodontic irrigants-resin cement vs. storage time was significant (p = 0.008), where 7 days of storage induced no difference between the groups, however, after 180 days, the groups for which CH or SH combined with RelyX U100 were used showed higher bond strength values than RelyX ARC, regardless of the irrigant solution. There was no difference between the use of RelyX ARC after 7 and 180 days of storage. For Rely X U100 180 days of storage increased the push-out bond strength when either CH or SH was used. The dual-cure and self-adhesive resin cements associated with CH or SH demonstrated similar immediate bond strength performance. The self-adhesive cement, however, showed improved bond strength over time when either irrigant was used.     

Degree of conversion and adhesion of methacrylate-based resin cements with phosphonic or phosphoric acid acrylate to glass fiber posts at different regions of intraradicular dentin

This study evaluated the degree of conversion (DC) and adhesion of methacrylate-based resin cements to glass fiber posts at different regions of intraradicular dentin. Single-rooted teeth (N?=?24, n?=?12 per group) were cut at the cement–enamel junction (CEJ), endodontically treated and post space (depth?=?8 mm) was prepared. Teeth were randomly divided into two groups according to the resin cements: (a) Group ML: methacrylate-based cement with phosphonic acid acrylate (Multilink Automix, Ivoclar Vivadent); (b) Group RXU: methacrylate-based cement with phosphoric acid acrylate (RelyX Unicem 2 Automix, 3 M ESPE). Fiber-reinforced composite root posts (RelyX Fiber Post, 3 M ESPE) were cemented according to the manufacturers’ instructions of the resin cements. Root slices of 2-mm thickness (n?=?3 per tooth) were cut below the CEJ 1, 3, and 5 mm apically. The DC of each section was analyzed with micro-Raman spectrometer and push-out test was performed in the Universal Testing Machine (0.5 mm/min). After debonding, all specimens were analyzed using optical microscope to categorize the failure modes. While data (MPa) were statistically evaluated using Kruskal Wallis, Mann–Whitney U tests for DC data 3-way ANOVA and Tukey’s tests were used (α?=?0.05). Regardless of the resin cement type, the mean push-out bond strength results (MPa), were significantly higher for the coronal slices (ML: 9.1?±?2.7; RXU: 7.3?±?4.1) than those of the most apical ones (ML: 7?±?4.9; RXU: 2.89?±?1.5) (p?=?0.002). Resin cement type and (p?p?=?0.002) significantly affected the DC values, while the interaction terms were not significant (p?=?0.606). Overall, DC was significantly higher for ML (67?±?8.2%) than RXU (26?±?8.8%) (p?相似文献   

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 timing for core preparation,luting cement type and root level on adhesion of fiber posts to intraradicular dentin

This study assessed the effect of timing of core preparation and luting cement on adhesion of fiber-reinforced composite (FRC) posts on different levels of intraradicular dentin when cemented with either conventional dual-polymerized or self-adhesive resin cement. Single-rooted human teeth (N = 80) were endodontically treated and randomly divided into 2 groups (n = 40) according to resin cement: (a) Conventional dual resin cement (Variolink II, V) or (b) Self-adhesive resin cement (RelyX U200, R). They were further divided into two subgroups according to timing of core preparation (n = 20): (a) immediate (i) or (b) delayed (d). FRC posts (Cytec Blanco) were cemented and the roots were sliced into discs at the coronal, middle, and apical levels. Push-out tests were then performed in a Universal Testing Machine (1 mm/min). Data (MPa) were analyzed using three-way ANOVA and Tukey’s tests considering the factors ‘core preparation time’, ‘luting cement’, and ‘root level’ (α = 0.05). Type of luting cement (p < 0.001), time of core preparation (p < 0.001), and root level (p < 0.001) significantly affected the bond strength results. R cement was more significantly affected by core preparation time (Ri: 2.91 ± 1.1; Rd: 4.83 ± 1.68) compared to V cement (Vi: 2.92 ± 1.63; Vd: 2.65 ± 1.6) (p < 0.05). Coronal region demonstrated significantly higher bond strength values than those of middle and apical third in all groups (coronal: 4 ± 1.9; middle: 3.1 ± 1.4; apical: 2.4 ± 1.1) (p < 0.05). Adhesive failure between cement and dentin was the most frequent (64%) followed by adhesive failure between cement and post (18%). Delayed core preparation can improve bond strength of FRC posts to intraradicular dentin when cemented with self-adhesive cement compared to conventional dual-polymerized resin cement.     

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

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

Adhesion of resin cements to contaminated zirconia resin cements on zirconia: effect saliva-contamination and surface conditioning

This study evaluated the adhesion of resin cements to zirconia after saliva contamination using resin cements with different chemistries. Zirconia discs (N?=?240, n?=?10 per group) were randomly divided into three groups: (a) C: No contamination (Control), (b) S: Contamination with saliva, (c) S?+?AA: Contamination with saliva followed by air-abrasion (CoJet). While half of the specimens were not conditioned, the other half were conditioned with 37.5% H₃PO₄ for 60?s. After rinsing, all specimen surfaces were silanized (Monobond Plus). Resin cements based on either methacrylate (Variolink II–VL) or MDP monomer (Panavia 21-PN) were polymerized on the substrates. The specimens were randomly divided into two further groups to be tested either after (a) 24?h dry storage at 37?°C or (b) thermocycling (×5000, 5–55?°C). Microshear bond (MSB) tests were conducted in a Universal Testing Machine and failure types were analyzed. Data were analyzed using Univariate analysis and Tukey’s tests (alpha = 0.05). While saliva contamination, 37.5% H₃PO₄ application (p?<?.001) and aging (p?<?.05) significantly affected the bond results, cement type did not show significant difference after aging (p?>?.05). Adhesive strength of PN (1.2–4.4?MPa) on saliva contaminated and etched zirconia was more stable than that of VL (0–2.8?MPa). After aging, bond strength results decreased the most with VL (3–100%) compared to PN (32–71%) but the decrease was less in the air-abraded groups after aging (VL: 3%; PN: 32%). Exclusively adhesive failures were experienced in all groups.     

Adhesion to zirconia as a function of primers/silane coupling agents,luting cement types,aging and test methods

This study evaluated the adhesion of resin cements to zirconia with different primers/silane coupling agents using two test methods with and without aging. Zirconia discs (Cercon) (N = 900, n = 15 per group) were ground finished to 2000 grit silicone carbide and randomly divided into seven groups: (a) C: No treatment (Control), (b) SG: Signum, (c) CL: Clearfil Ceramic Primer, (d) AP: Alloy Primer, (e) Monobond Plus, (f) ES-R: ESPE-Sil after Rocatec and (g) ES-C: ESPE-Sil after CoJet. Methacrylate (Variolink II-VL) and MDP based (Panavia F2.0-PN) dual-polymerized and self-adhesive resin cements (RelyX Unicem-RX) were adhered and polymerized accordingly. The specimens were further randomly divided into two groups to be tested after (a) 24-h dry storage at 37 °C and (b) thermocycling (×5000, 5–55 °C). Macroshear (MSB) and macrotensile bond tests (MTB) were conducted in an universal testing machine (crosshead speed: 1 mm/min) and failure types were analyzed after debonding. Data were analyzed using Univariate analysis and Tukey’s tests (α = 0.05). Two-parameter Weibull modulus, scale (m) and shape (0) were calculated. While primer/silane (p < 0.001), cement type (p < 0.001) and aging (p < 0.001) significantly affected the bond results, test method did not show significant difference (p = 0.237). In MSB test, Weilbul moduli were more favorable for MP-VL (4.2) and AP-PN (6) combinations and after aging for MP-VL (4.2) and AP-PN (5.66). In MTB test, after aging, Weilbul moduli were more favorable for AP-PN (5.41). Bond strength results mostly decreased with SG (24–92%) after aging. Cohesive failures in the cement were more frequent with PN (252) compared to VL (83).     

Adhesion of cast metal alloy and lithium disilicate copings luted to different core build-up materials with self-adhesive resin cement

This study evaluated the shear bond strength of two coping materials (non-nickel chrome-based cast alloy and lithium disilicate ceramic (IPS Empress) to four different core foundation materials (resin composite, cast metal alloy, lithium disilicate, and dentin), luted with adhesive resin cement (RelyX Unicem). Specimens (N = 56) were fabricated and divided into eight groups (n = 7 per group). Each coping material was luted with self-adhesive resin cement (RelyX Unicem) to the core materials. Bond strength was measured in a Universal Testing Machine (0.5 mm/min). Data were statistically analyzed using a two-way analysis of variance (ANOVA) and Tukey’s HSD tests (alpha = 0.05). Both core (p = 0.000) and coping material type (p = 0.000) significantly affected the mean bond strength (MPa) values. Interaction terms were also significant (p = 0.001). The highest bond strength results were obtained when lithium disilicate was bonded to lithium disilicate (21.48) with the resin cement tested. Lithium disilicate in general presented the highest bond results when bonded to all core materials tested (16.55–21.38) except dentin (3.56). Both cast alloy (2.9) and lithium disilicate (3.56) presented the lowest bond results on dentin followed by cast-alloy-cast alloy combination (3.82).     

Effect of experimental primers on hydrolytic stability of resin zirconia bonding

This study assessed the effect of experimental silane primers and two adhesive resin cements on resin zirconia adhesion strength. The surfaces of cut Y-TZP zirconia blocks (Lava? Frame), 16 mm × 16 mm × 4.5 mm, were pretreated twice. First, they were grit-blasted with Korox? alumina powder (110 μm) followed by silica-coating with Rocatec? Soft. Next, the blocks were randomly assigned into eighteen sub-groups (n = 6, N = 108) according to three primers (control ESPE Sil?, 1.0 vol.-% 3-acryloxypropyltrimethoxysilane, and 1.0 vol.-% 3-acryloxypropyltrimethoxysilane + 0.5 vol.-% bis-12-(triethoxysilyl)ethane), two in dentistry used resin cement products (Multilink? Speed, and Multilink? N), and three storage conditions (24 h dry, 1 month immersed in distilled water, and 6 months immersed in distilled water at room temperature) used. Onto each pretreated zirconia block, four cylindrical resin composite cement stubs were prepared and light-cured. The surface roughness, contact angle, and adhesion (shear bond) strength (SBS) were measured, and statistically analyzed (ANOVA, the Tukey’s test, p < 0.05). No statistical differences were observed in surface roughness values of different primer-treated zirconia groups. After six months of water aging, the shear bond strength of the groups that employed 1.0 vol.-% 3-acryloxypropyltrimethoxysilane (9.0 MPa ± 0.8 MPa), and the blend of 1 vol.-% 3-acryloxypropyltrimethoxysilane + 0.5 vol.-% bis-12-(triethoxysilyl)ethane (8.9 MPa ± 2.0 MPa) with Multilink? Speed resin composite cement were statistically insignificantly higher compared to using ESPE Sil? (8.7 MPa ± 1.8 MPa). The experimental primers may have potential to be used for long-term resin zirconia adhesion.     

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%).     

Effects of different surface treatments of zirconia on the bond strength of self-adhesive resinous cement

Purpose: The aim of this study was to evaluate the effects of different zirconia surface treatments on the bond strength of two self-adhesive resinous cements (SARC).

Methods: Two hundred and eight cylindrical specimens were obtained from Y-TZP zirconia (half with diameter 3.2 mm and half with 4.8 mm). After sintering and polishing, specimens were divided into four groups (n = 26), according to surface treatment: Control (no treatment); Sandblasting (Al₂O₃ particles); Rocatec (Al₂O₃ particles, tribochemical silica coating and silane application); Laser (Nd: YAG laser: 20 Hz, 100 mJ, 0.2 J/cm²). The surface roughness (Ra) was evaluated after the surface treatments, and the groups were divided into two subgroups (n = 13), according to the SARC tested: RelyX U200 and Bifix SE. The 2.2-mm cylinders were bonded to 4.8-mm cylinders and stressed until failure under shear using a universal testing machine. Bond strength and Ra were analyzed using ANOVA, and Tukey’s test (α = 0.05).

Results: Surface treatment was significant (p < 0.0001), but cement type (p = 0.73) was not. Related to roughness, significant differences were found for the treatment type (p < 0.0001), with laser being the treatment with higher Ra values.

Conclusions: Nd:YAG laser produced a rougher surface and a higher bond strength compared with sandblasting, silicatization, and control groups.     

The effect of polymerization mode on mechanical properties of commercial self-adhesive cements associated with hydroxyapatite

This study aimed to evaluate the mechanical properties of self-adhesive resin cements mixed with hydroxyapatite, as a function of the polymerization activation mode among a variety of commercial self-adhesive cements. Four cements (MaxCem Elite, Bifix SE, G-Cem, and RelyX U200) were mixed, combined with hydroxyapatite, dispensed into molds, and distributed into three groups, according to polymerization protocols: IP (immediate photoactivation for 40 s); DP (delayed photoactivation, 10 min self-curing plus 40 s light-activated); and CA (chemical activation, no light exposure). After polymerization, the specimens were stored at 37 °C for 24 h. After storage, a three-point bending test was performed at 0.5 mm/min. Flexural strength (S) and flexural modulus (E) were calculated. The fractured surfaces were analyzed with scanning electron microscopy (SEM) technique. Data were analyzed by two-way ANOVA/Tukey’s test (5%). The tested parameters varied according with the resin cements and polymerization protocols. Regarding the S means, MaxCem Elite, G-Cem, and RelyX U200 demonstrated dependence on photoactivation (immediate or delayed), whereas Bifix SE exhibited no dependence on the polymerization protocol. The same was observed for Bifix SE for the E means, which presented the best balanced formulation, irrespective of the activation protocol. SEM analysis exhibited the presence of bubbles and porosities in all of the fractured surfaces. Chemical activation is not a guarantee of a complete polymerization for most of the cements tested. Only one of the cements maintained its mechanical properties when chemically activated, important characteristic in clinical situations in which the curing light penetrating the bulk material can be attenuated or scattered.