The most well recognized technique for orthodontic bonding to porcelain surfaces is:

 # The most well recognized technique for orthodontic bonding to porcelain surfaces is:

A. Traditional acid-etch technique with phosphoric acid.

B. Chemical retention using 4-META coupling agent.

C. Chemical and micro-mechanical retention using hydrofluoric acid and a silane coupling agent.

D. Chemical retention using hydrofluoric acid only.

The correct answer is C. Chemical and micro-mechanical retention using hydrofluoric acid and a silane coupling agent

Explanation:
The most effective and well-recognized technique for bonding to porcelain involves etching the porcelain surface with hydrofluoric acid to create micro-mechanical retention, followed by the application of a silane coupling agent to enhance chemical adhesion. This combination ensures a strong bond between the orthodontic bracket and the porcelain surface.

• A: Phosphoric acid etching is effective for enamel but not adequate for porcelain bonding.
• B: 4-META is less commonly used for porcelain.
• D: Hydrofluoric acid alone provides micro-mechanical retention but lacks the chemical bond achieved with silane.