Thank you for having the interest to reply. The main issue is adhesion of the amalgam to the parent steel. This would be overcome by a thorough cleaning of the pit. My procedure would be as follows : get a pack of brake clean, use the wife's hair dryer and carefully put a right angle bend on the tip of the tube, blast the pit - this will remove most of the grease, oil, crud, and powder/ smoke residue. I would do this twice as it evaporates quite quickly. Then you would use a fairly concentrated solution of caustic soda - Na Oh. Beware this shit requires full P.P.E - safety glasses and rubber gloves, one drop of Caustic in your eye will crater the surface of the eye ball.... This process of using caustic is called scouring the steel. Removes all built up oils, waxes and carbonaceous material. After using the caustic - 20 mins, flush with a full jug of boiling water, this will remove remaining caustic and heat the chambers so they dry out. The next step is to use a cotton bud soaked in strong hydrochloric acid, this will remove some or all rust remaining in the pitting - again flush well with boiling water. By now you will have 2 things, a clean pit and a chamber avid for oxygen, it will start to rust real quick, just with atmospheric oxygen. The steel will be naked and oxygen hungry. You need to perform the last step just before your trip to the dentist. Hopefully your dentist will allow for your slightly deranged request and book it down as a standard tooth filling so you can claim it on your health insurance. Best of luck lol.