Effect of Different Adhesive Strategies and Time on Microtensile Bond Strength of a CAD/CAM Composite to Dentin

Effect of combining different 10-MDP-containing primers and cement systems on shear bond strength between resin cement and zirconia

PURPOSE

The longevity of zirconia restoration depends upon its esthetic, proper occlusion, marginal adaptation, and restoration retention. This study aimed to investigate the combination of 10-MDP-containing primers between the two commercial systems (Scotchbond Universal Plus Adhesive and Panavia V5) and airborne-particle abrasion on shear bond strength (SBS) between zirconia and resin cement.

METHODS

High translucency zirconia discs were sectioned and sintered according to the manufacturer's recommendations. The specimens were randomly applied with three different primers (Scotchbond Universal Adhesive, Tooth Primer, and Clearfil Ceramic Primer). Then, each group was bonded with Panavia V5 and RelyX™ Universal resin cements. Airborne-particle abrasion on the zirconia surfaces was also conducted using the manufacturer's bonding protocol for both resin cements. SBS was analyzed by a two-way ANOVA with Tukey's adjustment for multiple comparisons (α = 0.05).

RESULTS

Panavia V5 exhibited the highest SBS with Scotchbond Universal Adhesive (9.66±2.00 MPa) and Tooth Primer (8.47±2.08 MPa), respectively. As-sintered zirconia luted with primers and RelyXTM Universal resin cement exhibited lower SBS than that of Panavia V5. In regard to air-abrasion, air-abraded zirconia luted with Tooth Primer and Panavia V5 exhibited statistically significant higher SBS (29.26±3.26 MPa) than other groups (p<0.0001).

CONCLUSIONS

Combining primers from different adhesive cement systems may significantly enhance the bond strength. Zirconia luted with Scotchbond Universal Adhesive and Panavia V5 achieved the highest bond strength when combined with airborne-particle abrasion.

The effect of combining primers and cements from different cement systems on the bond strength between zirconia and dentin

OBJECTIVE

The aim of this study was to evaluate the influence of combining primers and cements from two different resin cement systems on the microtensile bond strength (μTBS) between zirconia and human dentin.

MATERIALS AND METHODS

A total of 120 specimens of zirconia cemented to dentin were allocated into eight groups based on cement type (RelyX Ultimate or Panavia V5) and primers (Tooth Primer, Clearfil Ceramic Primer and Scotchbond Universal Adhesive) combinations, applied to dentin or ceramic surfaces. Following artificial aging with 5000 thermocycles, μTBS tests were conducted. Statistical analysis was performed using One-way ANOVA and Tukey's post hoc tests (p ≤ 0.05), and failure modes were assessed.

RESULTS

The Panavia V5 cement system demonstrated the highest bond strength (19.4 ± 4.4 MPa), significantly higher than the other groups except when RelyX cement was used with Panavia primers (16.9 ± 3.7 MPa). Cohesive fractures within the cement layer were the predominant failure mode.

CONCLUSIONS

The combination of primers from different adhesive cement system brands may significantly affect the bonding effectiveness. Therefore, using products from a single product line of the same adhesive cement system, and following the manufacturer's recommendations for indications and use, is crucial for a more predictable clinical outcome.

Different surface treatment strategies on etchable CAD-CAM materials: Part 1-Effect on the surface morphology

STATEMENT OF PROBLEM

Polymer-based computer-aided design and computer-aided manufacturing (CAD-CAM) materials have either a high content of ceramic filler particles or a ceramic network structure. Proper etching of these materials is challenging. Therefore, it is relevant to assess different surface etching strategies and morphological alterations as a result of these techniques.

PURPOSE

The purpose of this 2-part in vitro study was to evaluate different etching strategies on the surface roughness and its relationship to the surface contact angle with a subsequent morphological characterization of different CAD-CAM materials.

MATERIAL AND METHODS

Two CAD-CAM polymer-based materials and 1 CAD-CAM ceramic material were selected for this study. The materials were treated with different strategies, including a combination of airborne-particle abrasion and an application of 9% hydrofluoric acid etching. After the surface treatment, roughness measurements (Sa) were assessed by using an optical profilometer on an area of 1.47 mm2. Subsequently, the contact angle on the surface was examined by means of the sessile drop technique and an optical contact angle meter. The data were analyzed by using a 2-way analysis of variance, the post hoc Tukey test (α=.05), and the Pearson correlation coefficient.

RESULTS

The 3 materials tested showed an increase in surface roughness when treated with surface airborne-particle abrasion. However, the materials with polymer in their composition concomitantly increased the contact angle. More hydrophilic surfaces were observed when hydrofluoric acid was applied, regardless of the composition of the materials. The surface roughness presented a strong positive linear tendency in the surface treatments used.

CONCLUSIONS

The application of airborne-particle abrasion on the surface of the polymer-based CAD-CAM materials increased the roughness and contact angle. However, the application of acid etching after the airborne-particle abrasion decreased the contact angle for polymer-based CAD-CAM materials, resulting in considerable enhancement of the surface quality for proper bonding.

Influence of the activation mode on long-term bond strength and endogenous enzymatic activity of dual-cure resin cements

Objective

To investigate the long-term microtensile bond strength (µTBS), interfacial nanoleakage expression (NL), and adhesive stability of dual-cure resin cements with/out light activation to dentin.

Materials and methods

Composite overlays (N = 20) were luted to deep dentin surfaces with RelyX Ultimate (RXU, 3M) or Variolink EstheticDC (VAR, Ivoclar-Vivadent). A universal adhesive was used for bonding procedures (iBond universal, Heraeus Kulzer). The resin cements were either self-cured (SC; 1 h at 37 °C) or dual-cured (DC; 20s light-cure followed by 15 min self-cure at 37 °C). Specimens were submitted to µTBS immediately (T₀) or after 1 year of laboratory storage (T₁₂). The fracture pattern was evaluated using scanning electron microscopy (SEM). Data were statistically analyzed with two-way ANOVA/Tukey test. Further, the NL was quantified and analyzed (chi-square test) and in situ zymography was performed to evaluate the endogenous enzymatic activity within the hybrid layer (HL) at T₀ and T₁₂ (Mann–Whitney test)_. The significance level for all statistical tests was set at p = 0.05.

Results

DC resulted in higher bond strength and decreased fluorescence at the adhesive interface, irrespective of the material and the storage period (p < 0.05). Significantly lower bonding performances (p < 0.05) and higher endogenous enzymatic activity (p < 0.05) were observed within the HL at T₁₂ compared to T₀ in all tested groups.

Conclusions

Light-curing the dual-cure resin cements, more than the cement materials, accounted for good bonding performances and higher HL stability over time when used with a universal adhesive.

Clinical significance

The curing condition influences the bonding performances of dual-cure resin cements to dentin when used with a universal adhesive.