Hi, i have a composite inlay on the lower back molar, it got slightly chipped recently from having a wisdom tooth extracted which was next to it. I now want a gold onlay and have the old composite inlay taken out and the decay cleaned from underneath it. My question is how many carats of gold would be best suited to a back molar inlay and do the nhs do this under their treatment? (would 22 carats be good?) Also is it a good idea for me to request them not to add nickel, beryllium and cobalt (base metals) as these are commonly allergic metals and I am generally sensitive to lots of things. Thank you.