New approach for evaluating metal-porcelain interfacial bonding

Area of Science:

• Biomaterials Science
• Materials Science
• Dental Materials

Background:

• Porcelain-fused-to-metal (PFM) restorations are widely used in dentistry.
• Evaluating the bond strength between porcelain and metal is crucial for restoration longevity.
• Fracture mechanics offers a quantitative approach to assess interfacial integrity.

Purpose of the Study:

• To quantitatively evaluate the bonding characteristics of PFM systems.
• To determine the strain energy release rate (SERR) at the metal-porcelain interface.
• To compare the adhesion of different metal alloys (gold, palladium, nickel-chromium) and titanium.

Main Methods:

• PFM specimens were fabricated using commercially pure titanium and three metal alloys.
• Specimens were subjected to controlled 4-point bending tests to induce interfacial fracture.
• Strain energy release rate was calculated from load-displacement data; interfacial areas were examined using SEM.

Main Results:

• Mean SERR values varied significantly across materials: Gold (72.7 J/m²), Palladium (58.5 J/m²), Nickel-Chromium (39.4 J/m²), and Titanium (16.6 J/m²).
• SEM analysis revealed fracture predominantly within the porcelain layer near the interface.
• Gold alloys exhibited the highest SERR, suggesting superior adhesion.

Conclusions:

• The fracture mechanics approach provides a reliable method for assessing PFM bond strength.
• Gold alloys demonstrate the strongest adhesion among the tested materials, while titanium shows the weakest.
• Findings offer valuable insights for selecting appropriate PFM materials for dental applications.