Docs can you explain, is it safe to replace deep amalgam fillings with composite fillings?

Safe, yes: If you are asking is it dangerous, the answer is no. But replacing perfectly good fillings (even if they are silver) can cause problems, including cracked teeth and pulpal tissue that becomes non-vital, all due to the trauma of the drill. You accept those risks when replacing a bad filling or fixing a cavity, but do you accept them in this case? Advice is accept the risks or leave them alone.

Risk vs. reward?: Any time we perform a service, there are always slight risks inherent in the specific procedure. Having said that, in general replacing a deep amalgam filling with a composite filling is not problematic. I would ask your own dentist to evaluate each tooth on a case by case basis to better ascertain the risks and give you a more accurate answer to your question.

Safe and predictable: Amalgam fillings over time can crack and decay. Replacing them with composite resin is a predictable, safe and long term solution.

To quote Dr Isidore Rosenfeld's grandmother, "In every medicine there's a little poison:" Pro's and con's should be discussed with your Dentist. I have silver fillings that are over 70 years old. Yes, required preparation can undermine enamel. But tooth-colored fillings wear out quickly (~10 years. Safe to do replacements, but learn all you can first.