Evaluation of shear bond strength of zirconia-based monolithic CAD-CAM materials to resin cement after different surface treatments.

OBJECTIVE: To compare the shear bond strength of resin cement to zirconia-based monolithic CAD-CAM materials subjected to different surface treatments. METHODS: 2 brands of monolithic zirconia blocks (Vita YZ HT, Sirona inCoris TZI), yttrium-stabilized tetragonal zirconia (IPS e.max ZirCAD) and zirconia-reinforced lithium silicate ceramic (Vita Suprinity) were divided into six groups according to the surface treatment received: no treatment (control), HF acid etching, sandblasting, sandblasting + Er:YAG laser irradiation, Er:YAG laser irradiation and CoJet. Composite resin cylinders were bonded to blocks with self-adhesive resin cement (Theracem). Shear bond strength was evaluated after thermocyling. Failure modes were examined using SEM. Data was analyzed statistically by using 2-way ANOVA and post-hoc Tukey's test (P < 0,05). RESULTS: The bond strength was significantly affected by the surface treatment and the type of CAD-CAM blocks (P < 0,001). Surface treatment with CoJet revealed significantly higher bond strength compared to sandblasting in Y-TZP and monolithic zirconia specimens. CONCLUSIONS: Monolithic zirconia blocks showed higher bond strength values compared to Y-TZP zirconia block in sandblasting and CoJet groups. HF acid etching is more effective than sandblasting and CoJet for Vita Suprinity.

Evaluation of shear bond strength of zirconia-based monolithic CAD-CAM materials to resin cement after different surface treatments

Objective: To compare the shear bond strength of resin cement to zirconia-based monolithic CAD-CAM materials subjected to different surface treatments. Methods: 2 brands of monolithic zirconia blocks (Vita YZ HT, Sirona inCoris TZI), yttrium-stabilized tetragonal zirconia (IPS e.max ZirCAD) and zirconia-reinforced lithium silicate ceramic (Vita Suprinity) were divided into six groups according to the surface treatment received: no treatment (control), HF acid etching, sandblasting, sandblasting + Er:YAG laser irradiation, Er:YAG laser irradiation and CoJet. Composite resin cylinders were bonded to blocks with self-adhesive resin cement (Theracem). Shear bond strength was evaluated after thermocyling. Failure modes were examined using SEM. Data was analyzed statistically by using 2-way ANOVA and post-hoc Tukey's test (P < 0,05). Results: The bond strength was significantly affected by the surface treatment and the type of CAD-CAM blocks (P < 0,001). Surface treatment with CoJet revealed significantly higher bond strength compared to sandblasting in Y-TZP and monolithic zirconia specimens. Conclusions: Monolithic zirconia blocks showed higher bond strength values compared to Y-TZP zirconia block in sandblasting and CoJet groups. HF acid etching is more effective than sandblasting and CoJet for Vita Suprinity

Evaluation of air-particle abrasion of Y-TZP with different particles using microstructural analysis.

BACKGROUND: This study evaluated the effect of air-particle abrasion with different particle sizes on the surface roughness and phase transformation of yttria-stabilized tetragonal zirconia ceramics (Y-TZP). METHODS: Eighty-four Y-TZP discs of 15 mm diameter and 1.0 mm thickness were fabricated. The samples were divided into four groups (n = 21): (1) air-particle abrasion with 30 µm CoJet sand blast coating agent (CoJet, 3M ESPE); (2) 50 µm Al2O3 particles; (3) 110 µm Al2O3 particles; and (4) 250 µm Al2O3 particles. Each group was further divided into three subgroups each (n = 7) and treated for 5 seconds, 15 seconds and 30 seconds. Mean surface roughness was determined using a profilometer. The surfaces were analysed with a scanning electron microscope. XRD analysis was employed and the relative amount of the monoclinic phase was calculated. The results were statistically analysed by two-way analysis of variance (ANOVA, p < 0.05). RESULTS: Air-particle abrasion with 250 µm Al2O3 particles for 30 seconds had the highest surface roughness (p < 0.001) and a significantly higher amount of monoclinic phase compared to air-particle abrasion with 30 µm, 50 µm and 110 µm particles (p < 0.001). CONCLUSIONS: Duration and particle size of air-particle abrasion affects the roughness and phase transformation of Y-TZP. Longer treatment times with larger particles may result in degradation of material.

The retentive effects of pre-fabricated posts by luting cements.

The purpose of this study was to compare the retention of two different pre-fabricated posts cemented to the root canal with four different adhesive luting cements and a zinc phosphate cement. The crowns of 100 freshly extracted human mandibular central and lateral incisors were removed at the cementoenamel junction and divided into two main groups (A = ParaPost and B = Flexi-Post) and further divided into five subgroups to evaluate the effects of five different cements (Rely-X ARC, Panavia F, ParaPost Cement, Flexi-Flow Natural and Adhesor) each with 10 samples. Post-holes were prepared on all of the roots following the manufacturer's instructions. Each sample was placed into a specialized jig and tensile strength tests performed by using testing machine with a crosshead speed of 0.638 cm min(-1) and force applied until failure. The data were analysed with one-way anova (Post Hoc a Scheffe's S test) and two-way anova (P < 0.001). The Flexi-Post dowels had a mean of 54.21 kg (s.d. = 9.37) and demonstrated statistically higher retention than ParaPost dowels with a mean of 33.93 kg (s.d. = 10.69) for all of the cement groups (P < 0.001). In Flexi-Post and ParaPost dowel groups; Rely-X ARC was statistically higher than the Panavia F, ParaPost Cement, Flexi-Flow Natural and Adhesor (P < 0.05). Adhesor was significantly lower than the other subgroups (P < 0.05). Resin luting cements have demonstrated very high tensile strength potential for a strong bond to dentin.

Shear bond strength of resin luting cement to glass-infiltrated porous aluminum oxide cores.

STATEMENT OF PROBLEM: Resin bonding surface treatment methods for conventional silica-based dental ceramics are not reliable for glass infiltrated high alumina content In-Ceram ceramics. PURPOSE: This study developed an alternative surface treatment to improve resin bonding of glass-infiltrated aluminum oxide ceramic blasting with diamond particles and then observed the efficiency of this treatment. Material and methods. In-Ceram test specimens were prepared and divided into 2 groups. All specimens were sandblasted with Al(2)O(3), and blasted with diamond particles and 2 adhesive resins were applied. After bonding and storage in humid conditions, shear bond strength values were measured with a universal testing machine. Surface roughness and fracture interfaces were determined with a perthometer and a SEM. RESULTS: The highest bond strength was obtained on the samples blasted with diamond particles (group II). The differences between the 2 groups and the 2 adhesive resin cements were both statistically significant. CONCLUSION: Panavia-Ex cement exhibited higher bond strength than Super-Bond cement. This higher bond strength was attributed to ceramic oxide and ester bond and the mechanical properties of Panavia-Ex cement.

Comparison of load transfer by implant abutments of various diameters.

The effects of diameter and position of implants on displacement and stress distribution, were investigated. ITI Hollow Cylinder two-stage implants with various diameters (3.5 mm, 4.5 mm and 6 mm) and positions are compared on the basis of a two dimensional finite element analysis. The mathematical results of this study demonstrate that, using conventional assumptions for stress levels in the crestal bone, relatively large diameter implants are preferable in the posterior mandibular area.

Comparison of load transfer by angulated, standard and inclined implant abutments.

In order to avoid improper loading of implants, the type of prosthesis, as well as the number, localisation and position of the abutments, should be analysed. In this study three-unit fixed partial prostheses in the posterior mandibular region, supported by an angulated, standard or inclined Bonefit ITI Hollow-Cylinder two-stage implant connected to a natural tooth, are modelled and the stress distributions investigated using the finite element method. It is suggested that the angulated or inclined implant abutments may be recommended because of lower stress around the crestal region of the implant bone interface.