Bonding between titanium and dental porcelain: a systematic review

Bonding of ceramics to silver-coated titanium-A combined theoretical and experimental study

It would be very beneficial to have a method for joining of ceramics to titanium reliably. Although several techniques have been developed and tested to prevent extensive interfacial chemical reactions in titanium-ceramic systems, the main problem of the inherent brittleness of interfaces was still unsolved. To overcome this problem also in dental applications, we decided to make use of an interlayer material that needs to meet the following requirements: First, it has to be biocompatible, second, it should not melt below the bonding temperatures, and third, it should not react too strongly with titanium, so that its plasticity will be maintained. Considering possible material options only the metals: gold, platinum, palladium, and silver, fulfill the first and second requirements. To find out-without an extensive experimental testing program-which of the four metals fulfills the third requirement best, the combined thermodynamic and reaction kinetic modeling was employed to evaluate how many and how thick reaction layers are formed between the interlayer metals and titanium. With the help of theoretical modeling, it was shown that silver fulfills the last requirement best. However, before starting to test experimentally the effect of the silver layer on the mechanical integrity of dental ceramic/Ag/Ti joints it was decided to make use of mechanical analysis of the three-point bending test, the result of which indicated that the silver layer increases significantly the bond strength of the joints. This result encouraged us to develop a new technique for plating silver on titanium. Subsequently, we executed numerous three-point bending tests, which demonstrated that silver-plated titanium-ceramic joints are much stronger than conventional titanium-ceramic joints. Hence, it can be concluded that the combined thermodynamic, reaction kinetic, and mechanical modeling method can also be a very valuable tool in medical research and development work.

Surveillance study on the application of titanium and its alloys to removable dental prostheses

This review describes individual studies of removable dental prostheses, evaluated their performance and clinical applicability for the proposal to expand health insurance coverage of titanium and its alloys to removable dental prostheses. Titanium and its alloys have become clinically applicable as prosthetic materials by improving dental casting systems. They have high biosafety and good mechanical properties, are excellent substitutes for the silver-palladium-gold alloys for casting, and are highly useful for removable dental prostheses. Therefore, the introduction of health insurance coverage for removable dental prostheses made of titanium and its alloys is worthy of consideration.

The effect of nanocoatings of SiO2, TiO2, and ZrO2 on titanium-porcelain bonding

STATEMENT OF PROBLEM

Durable titanium-porcelain bonding is challenging because of the formation of a thick oxide layer on the surface during porcelain firing.

PURPOSE

The purpose of this in vitro study was to evaluate how atomic layer deposition (ALD) of different oxide coatings affected titanium-porcelain bonding and failure types.

MATERIAL AND METHODS

Forty-four airborne-particle abraded Type-2 titanium specimens were coated by ALD with either SiO₂, TiO₂, or ZrO₂ (n=11) at a thickness of 30 nm, whereas control specimens were left uncoated (n=11) (airborne-particle abraded only). The surface roughness of the specimens was analyzed with a profilometer before applying porcelain (Vita Titankeramic). Titanium-porcelain bonding was analyzed by using a 3-point bend test. Surface properties and titanium-porcelain interfaces were examined under scanning electron microscopy combined with energy-dispersive spectroscopy, and failure types were evaluated by using a stereomicroscope. Surface roughness and bond strength data were analyzed by 1-way ANOVA and Tukey HSD tests. Failure type data were analyzed by the Fisher-Freeman-Halton exact test (α=.05).

RESULTS

All nanocoatings increased surface roughness values, but only TiO₂ and ZrO₂ coatings showed statistically significant higher roughness than the control surfaces (P<.001). Specimens coated with SiO₂ (28.59 ±4.37 MPa) and TiO₂ (26.86 ±3.66 MPa) presented significantly higher bonding strength than control (22.04 ±4.59 MPa) specimens (P<.01). Fracture types of different groups were not statistically different (P>.05).

CONCLUSIONS

Nanocoating titanium surfaces with SiO₂ and TiO₂ by using the ALD technique significantly improved titanium-porcelain bonding.

Bond strength of commercial veneering porcelain to experimental cast Ti-Cr alloy

This study evaluated bond strengths of three commercial veneering porcelains to experimental cast titanium-chromium (Ti-Cr) alloy and commercially pure titanium (cp-Ti) via three-point bending test. After the bending test, the fractured specimens were analyzed using an electron probe microanalyzer (EPMA). The Ti-Cr specimens showed lower bond strengths than the cp-Ti specimens, irrespective of the layering porcelain material; however, all the strengths exceeded the minimum requirement of ISO 9693-1:2012 (>25 MPa). EPMA revealed that titanium and/or chromium elements were detected on the debonded porcelain surface of the Ti-Cr and cp-Ti specimens in the case of the higher bond strength. Contrastingly, the residual porcelain was retained on the metallic surface in the case of the lower bond strength. Although porcelain bonding to the titanium alloy is influenced by porcelain type, the Ti-Cr alloy could be feasible for porcelain-fused-to-metal restorations.

Retentive Force of Glass-Ceramic Soldered Customized Zirconia Abutment Copings with Prefabricated Titanium Bases

Two-piece abutments consisting of customized zirconia abutment copings and prefabricated titanium bases are popular due to their biological and esthetic advantages. Glass-ceramic solder (GS) is an alternative biocompatible connective agent. This in vitro study evaluated the retentive force of GS in comparison to classical resin composite cements (RC) after artificial aging and autoclaving. Ninety specimens consisting of prefabricated titanium bases and zirconia abutment copings were fabricated. The two parts of each specimen were fixed either by RC (n = 30) or GS with a luting space of either 30 µm (n = 30) or 100 µm (n = 30). Ten specimens of each group underwent autoclaving before artificial aging (water storage, thermocycling). Twenty specimens (including the 10 autoclaved specimens) of each group were exposed to a mechanical load. The retentive force between the zirconia and titanium in all specimens was determined. A fractographic analysis was performed to analyze the fracture surfaces of the GS specimens. The RC- and GS-connected two-piece abutments showed no relevant differences, independent of the luting space. RC appears to be more vulnerable to the thermal and mechanical loads than GS. Thus, GS may be an appropriate alternative to RC for two-piece abutments, especially for patients with enhanced biocompatibility requirements.

Cast, milled and EBM-manufactured titanium, differences in porcelain shear bond strength

The objectives were to analyze the oxide layer generated between titanium and porcelain during firing and compare it in different manufacturing techniques: cast, milled and EBM-technique. Seventy two specimens were manufactured, subdivided according to surface treatment: time of passivation (P) and no time of passivation (NP) before porcelain firing. Specimens from each group were analyzed with scanning electron microscopy: one only fired once, and one subjected to six firings. Remaining specimens were subjected to shear bond strength test. The EBM-produced NP-group had highest mean value (25.0 MPa) and the milled P-group showed lowest mean value (18.5 MPa) when all factors were compared. No significant difference was detected according to time of passivation. SEM showed consistent and well-defined boundary between the different layers. Time of passivation and impact on oxide growth was not detected. The bond strength of porcelain to milled titanium is lower when compared to cast titanium and EBM-produced titanium.

Evaluation and comparison of shear bond strength of porcelain to a beryllium-free alloy of nickel-chromium, nickel and beryllium free alloy of cobalt-chromium, and titanium: An in vitro study

Aims:

The aim of this study was to evaluate and compare the shear bond strength of porcelain to the alloys of nickel-chromium (Ni-Cr), cobalt-chromium (Co-Cr), and titanium.

Materials and Methods:

A total of 40 samples (25 mm × 3 mm × 0.5 mm) were fabricated using smooth casting wax and cast using Ni-Cr, Co-Cr, and titanium alloys followed by porcelain buildup. The samples were divided into four groups with each group containing 10 samples (Group A1–10: sandblasted Ni-Cr alloy, Group B1–10: sandblasted Co-Cr alloy, Group C1–10: nonsandblasted titanium alloy, and Group D1–10: sandblasted titanium alloy). Shear bond strength was measured using a Universal Testing Machine.

Statistical Analysis Used:

ANOVA test and Tukey's honestly significance difference post hoc test for multiple comparisons.

Results:

The mean shear bond strength values for these groups were 22.8960, 27.4400, 13.2560, and 25.3440 MPa, respectively, with sandblasted Co-Cr alloy having the highest and nonsandblasted titanium alloy having the lowest value.

Conclusion:

It could be concluded that newer nickel and beryllium free Co-Cr alloys and titanium alloys with improved strength to weight ratio could prove to be good alternatives to the conventional nickel-based alloys when biocompatibility was a concern.

Surface characterization of Ti and Y-TZP following non-thermal plasma exposure

Novel non-thermal plasma (NTP) technology has the potential to address the bonding issues of Y-TZP and Ti surfaces. This study aims to chemically characterize and evaluate the surface energy (SE) of Y-TZP and Ti surfaces after NTP application. Y-TZP and Ti discs were treated with a hand-held NTP device followed by SE evaluation. Spectra of Y-TZP 3d and Ti 2p regions, survey scans, and quantification of the elements were performed via X-ray photoelectron Spectroscopy (XPS) prior and after NTP. Separate Y-TZP and Ti discs were NTP treated for contact angle readings using (10-methacryloyloxydecyl dihydrogenphosphate) MDP primer. Significant augmentation of SE values was observed in all NTP treated groups. XPS detected a large increase in the O element fraction on both Y-TZP and Ti surfaces. Reduction of contact angle reading was obtained when the MDP primer was placed on NTP treated Y-TZP. Ti surface showed high SE before and after NTP application on Ti surfaces. NTP decreased C and increased O on both surfaces independently of application protocol. Wettability of MDP primer on Y-TZP was significantly increased after NTP. The high polarity obtained on Y-TZP and Ti surfaces after NTP applications appear promising to enhance bonds.