Can anyone help with some Dental billing questions?

Hello, I recently made the switch from working in medical billing to working at a dental office. While I have worked at once in the past, and I am a little rusty. My question is regarding posterior composites. If the patient's plan downgrades to amalgam, when I am calculating their co-payment, would it be the... show more Hello, I recently made the switch from working in medical billing to working at a dental office. While I have worked at once in the past, and I am a little rusty.

My question is regarding posterior composites.
If the patient's plan downgrades to amalgam, when I am calculating their co-payment, would it be the difference between our composite fee and insurance amalgam fee, or would it be based on insurance composite / insurance amalgam?

Thank you!