Effect of surface treatments on adhesion of low-fusing porcelain to titanium as determined by strain energy release rate

Bond strength of ceramic veneered CAD-milled alloy upon prolonged sintering

OBJECTIVES

Ceramic-sintering affects bond strength and longevity of metal-ceramic. This study investigated the effect of sintering temperatures and times on metal-ceramic bond strength vis-a-vis interfacial fracture toughness.

MATERIALS AND METHODS

One hundred eighty rectangular-shaped (25 × 8 × 1 mm) casting (Auriloy® (CA)) and CAD-milling (Ceramill Sintron® (MA)) alloys were prepared and randomly veneered with ceramic at normal (930 °C; (TN)), increased (940 °C; (TI)), and extremely increased (950 °C; (TE)) sintering temperatures and normal (1 min; (HN)), increased (2 min; (HI)), and extremely increased (3 min; (HE)) sintering time (n = 10/group). Pre-cracked was subjected to four loading-unloading cycles at 0.05 mm/min speed to determine interfacial fracture toughness from strain energy release rate (G). Microstructures were examined with a scanning electron microscope (SEM), energy-dispersive X-ray (EDX), and atomic force microscopy (AFM). ANOVA and Tukey comparisons were determined for significant differences (α = 0.05).

RESULTS

Significant differences in G due to the effect of alloy, sintering temperature, and time (p < 0.05) were indicated. MA revealed higher G than CA. Raising temperatures enabled increasing G for CA, not for MA. Extended sintering permitted increasing G for both alloys. Rougher surface of MA than CA was observed. Interfacial ion exchange was differently indicated between CA and MA.

CONCLUSIONS

Bond strength was influenced by alloy, sintering temperature, and time. Ceramic has better adhesion to MA than CA. Enhancing bond for CA was succeeded through increasing sintering temperature and time, whereas through extended sintering for MA.

CLINICAL RELEVANCE

MA offers stronger bond than CA. Enhancing bond is suggested by extended sintering. Raising temperature can enhance bond for CA, not for MA.

Influence of Sandblasting and Chemical Etching on Titanium 99.2-Dental Porcelain Bond Strength

The metal-ceramic interface requires proper surface preparation of both metal and ceramic substrates. This process is complicated by the differences in chemical bonds and physicochemical properties that characterise the two materials. However, adequate bond strength at the interface and phase composition of the titanium-bioceramics system is essential for the durability of dental implants and improving the substrates' functional properties. In this paper, the authors present the results of a study determining the effect of mechanical and chemical surface treatment (sandblasting and etching) on the strength and quality of the titanium-low-fusing dental porcelain bond. To evaluate the strength of the metal-ceramic interface, the authors performed mechanical tests (three-point bending) according to EN ISO 9693 standard, microscopic observations (SEM-EDS), and Raman spectroscopy studies. The results showed that depending on the chemical etching medium used, different bond strength values and failure mechanisms of the metal-ceramic system were observed. The analyzed samples met the requirements of EN ISO 9693 for metal-ceramic systems and received strength values above 25 MPa. Higher joint strength was obtained for the samples after sandblasting and chemical etching compared to the samples subjected only to sandblasting.

Effect of different firing atmospheres on debonding strength of dental porcelain fused to commercially pure titanium

An in vitro investigation was performed to evaluate the bonding characteristics of porcelain fused to metal (PFM)/commercially pure titanium (cp Ti, grade II) in three firing atmospheres of under vacuum and using two noble gases argon (Ar) and helium (He). Three groups of porcelain veneers firing under vacuum, Ar, and He were prepared to evaluate the bonding of porcelain fused to the cold-rolled cp Ti. The bond strength of PFM durability by a three-point bending test, phases, microhardness of cp Ti after firing processes, and fractures were measured and evaluated. Results show the microhardness of cp Ti in group of porcelain firing under He atmosphere was significantly lower than that of the two other groups, which were in vacuum and Ar (P < .05). X-ray diffraction showed the He group produced in relatively small amounts of TiO₂ and TiO oxides than other groups but featured relatively high quantity of airhole defects in the porcelain body leading to the lowest bond strength. The Ar group presented the highest bond strength of comparing with the groups under vacuum and using He (P < .05). Although the firing processes in He could efficiently prevent the diffusion of oxygen into Ti, the porcelain-cp Ti bond strength using Ar protective atmosphere presented the advantage to achieve clinical requirement because porcelain firing under He revealed prominent voids and defects within the body of porcelain.

Effect of atmospheric plasma versus conventional surface treatments on the adhesion capability between self-adhesive resin cement and titanium surface

PURPOSE

The aim of this study was to evaluate the effects of atmospheric plasma (APL) versus conventional surface treatments on the adhesion of self-adhesive resin cement to Ti-6Al-4V alloy.

MATERIALS AND METHODS

Sixty plates of machined titanium (Ti) discs were divided into five groups (n=12): 1) Untreated (CNT); 2) Sandblasted (SAB); 3) Tribochemically treated (ROC); 4) Tungsten CarbideBur (TCB); 5) APL treated (APL). SEM analysis and surface roughness (Ra) measurements were performed. Self-adhesive resin cement was bonded to the Ti surfaces and shear bond strength (SBS) tests, Ra and failure mode examinations were carried out. Data were analyzed by one-way analysis of variance and chi-squared test.

RESULTS

The lowest SBS value was obtained with CNT and was significantly different from all other groups except for APL. The ROC showed the highest SBS and Ra values of all the groups.

CONCLUSION

It was concluded that the effect of APL on SBS and Ra was not sufficient and it may not be a potential for promoting adhesion to titanium.

Enhancement of the adhesion between cobalt-base alloys and veneer ceramic by application of an oxide dissolving primer

OBJECTIVES

Uncontrolled formation of an oxide layer on base metal alloy surface impairs adhesion between the alloy and veneer ceramic. The aim of this study was to investigate the influence of an oxide dissolving primer on the adhesion between cobalt-base alloys and a veneer ceramic.

METHODS

Combinations of two cobalt-base alloys (Bärlight/BL, Cara Process/CP) and one veneering ceramic (HeraCeram) were investigated. 40 rectangular specimens of each alloy were covered with the veneer ceramic; half of the alloy samples were treated with an oxide dissolving primer (NP-Primer) prior to veneering (n=20). Subsequently, the veneering surface was ground flat and notched using the single-edge V-notched-beam method. Then specimens were loaded in a four-point bending test and the critical load to induce stable crack extension at the adhesion interface was determined, in order to calculate the strain energy release rate (G, J/m(2)). Finally, fracture surfaces of the specimens were evaluated by scanning electron microscopy (SEM).

RESULTS

Strain energy release rates averaged between 24.1J/m(2) and 28.8 J/m(2). While application of the primer statistically significantly increased adhesion between alloy and ceramic with the BL specimens (p=0.035), no significant influence was found for the CP specimens (p=0.785). For both material combinations, SEM analysis revealed enhanced wetting of the alloy surfaces with ceramic after application of the primer.

SIGNIFICANCE

Application of an oxide dissolving primer increases the wettability of cobalt-base alloy surfaces and thus improves adhesion to veneering ceramics. This may enhance the long-term stability of bilayer restorations made from these materials.

Withdrawn. Duplicate: Effect of gold sputtering on the adhesion of porcelain to cast and machined titanium

STATEMENT OF PROBLEM

The bond strength of porcelain to titanium is insufficient to provide a clinically acceptable alternative to existing alloys for metal ceramic restorations.

PURPOSE

The purpose of the study was to investigate the effect of gold coating on the adhesion of porcelain to titanium.

MATERIAL AND METHODS

Forty titanium plates (25 × 8 × 1 mm) were prepared by casting and machining procedures to make 2 groups of each type (n=10). All plates were subjected to airborne-particle abrasion with alumina powder. One of each of the cast and machined groups was gold sputtered. A layer of porcelain was built up onto the titanium plates of all groups with a conventional technique. A precrack was created at the center of the specimen. Specimens were then subjected to a 4-point bending test with a universal testing machine. The load recorded from the test was used to determine adhesion in terms of the strain energy release rate (G value). The data were analyzed with ANOVA and post hoc testing (α=.05). The interfacial area of the tested specimen was then examined with scanning electron microscopy.

RESULTS

The G values of the gold-sputtered groups were significantly higher than those of the uncoated groups for both cast and machined groups (P<.05). No significant differences were noted within the groups.

CONCLUSIONS

The adhesion between porcelain and titanium was significantly improved when titanium was sputter coated with gold in both the cast and machined groups.

Effect of gold sputtering on the adhesion of porcelain to cast and machined titanium

STATEMENT OF PROBLEM

The bond strength of porcelain to titanium is insufficient to provide a clinically acceptable alternative to existing alloys for metal ceramic restorations.

PURPOSE

The purpose of the study was to investigate the effect of gold coating on the adhesion of porcelain to titanium.

MATERIAL AND METHODS

Forty titanium plates (25 × 8 × 1 mm) were prepared by casting and machining procedures to make 2 groups of each type (n=10). All plates were subjected to airborne-particle abrasion with alumina powder. One of each of the cast and machined groups was gold sputtered. A layer of porcelain was built up onto the titanium plates of all groups with a conventional technique. A precrack was created at the center of the specimen. Specimens were then subjected to a 4-point bending test with a universal testing machine. The load recorded from the test was used to determine adhesion in terms of the strain energy release rate (G value). The data were analyzed with ANOVA and post hoc testing (α=.05). The interfacial area of the tested specimen was then examined with scanning electron microscopy.

RESULTS

The G values of the gold-sputtered groups were significantly higher than those of the uncoated groups for both cast and machined groups (P<.05). No significant differences were noted within the groups.

CONCLUSIONS

The adhesion between porcelain and titanium was significantly improved when titanium was sputter coated with gold in both the cast and machined groups.

Effect of investment type and mold temperature on casting accuracy and titanium-ceramic bond

This study evaluated the casting accuracy of crown margins and metal-ceramic shear bond strength (SBS) of pure titanium injected into casting molds made using 2 investment types at 3 mold temperatures. Sixty crown (30-degree beveled finish line) and 60 cylinder (5mm diameter × 8mm high) patterns were divided into 6 groups (n=10), and cast using a phosphate-bonded investment (P) and a magnesium oxide-bonded investment (U), at 400°C (groups P400 and U400), 550°C (groups P550 and U550) and 700°C (groups P700 and U700) mold temperatures. Crown margins were recorded in impression material, the degree of marginal rounding was measured and margin length deficiencies (µm) were calculated. Titanium-ceramic specimens were prepared using Triceram ceramic (2mm high) and SBS was tested. Failure modes were assessed by optical microscopy. Data were subjected to two-way ANOVA and Tukey's HSD test (α=0.05). For casting accuracy, expressed by marginal deficiency (µm), investment U provided more accurate results (64 ± 11) than P (81 ± 23) (p<0.001). The increase in temperature resulted in different effects for the tested investments (p<0.001), as it provided better casting accuracy for U700 (55 ± 7) and worse for P700 (109 ± 18). Casting accuracy at 700°C (82 ± 31) was significantly different from 400°C (69 ± 9) and 550°C (68 ± 9) (p<0.05). For SBS, there was no significant differences among the groups for factors investment (p=0.062) and temperature (p=0.224), or for their interaction (p=0.149). Investment U provided better casting accuracy than investment P. The SBS was similar for all combinations of investments and temperatures.