Differences between nickel-chromium and cobalt-chromium alloys, and how to choose?

In comparison, cobalt-chromium alloys are currently more prevalent in dental applications, primarily used for fabricating dental restorations such as crowns and bridges. Here is a comparative analysis of these two dental alloy materials:

Advantages:

Biocompatibility: Both cobalt-chromium and nickel-chromium alloys exhibit excellent biocompatibility, with minimal tissue irritation and reduced risk of allergic reactions. Generally, cobalt-chromium slightly outperforms nickel-chromium; scoring a 9 and 8 out of 10 respectively.

Mechanical Properties: Cobalt-chromium alloys possess high strength and hardness, coupled with superior wear resistance, making them suitable for long-term dental restorations.

Corrosion Resistance: Both materials exhibit nearly equivalent corrosion resistance.

Cost-Effectiveness: Compared to precious metal alloys and full-ceramic zirconia, nickel-chromium alloys offer the lowest cost, providing a higher cost-benefit ratio.

Disadvantages:

Aesthetics: Cobalt-chromium alloys have a darker appearance, less aesthetically pleasing than ceramic restorations, and are typically used for posterior tooth restorations.

Processing Difficulty: Cobalt-chromium alloys are more challenging to process and require specialized equipment and techniques.

Potential Health Risks: Although cobalt-chromium alloys have good biocompatibility, long-term use may result in the release of trace metal ions, posing potential health risks to sensitive individuals.

When choosing between cobalt-chromium and nickel-chromium alloys, the following factors should be considered:

Biocompatibility: Nickel-chromium alloys may cause allergic reactions in some individuals due to the presence of nickel, whereas cobalt-chromium alloys generally offer better biocompatibility.

Mechanical Properties: Select an alloy with appropriate strength and hardness based on the location and usage requirements of the restoration.

Aesthetics: Anterior tooth restorations typically require better aesthetics, and materials such as ceramic restorations or other more aesthetically pleasing options should be chosen.

Cost: Based on the patient’s economic situation and treatment budget, choose an alloy with a high cost-benefit ratio.

Patient Health Status: For patients with a history of metal allergies or specific health conditions, materials with better biocompatibility should be selected.

Overall, while cobalt-chromium seems to outperform nickel-chromium in various aspects, nickel-chromium alloys are not without merits. They generally have lower hardness, easier processing, and are more affordable, making them accessible to most patients while still maintaining decent biocompatibility and physical properties, suitable for the majority of individuals.

However, it is important to note that these comparisons are limited to these two materials. The use of metals as dental bases is becoming less common, with the digital processing of zirconia full-ceramic materials emerging as the mainstream in this era.