Interesting point. I do like you, find decay under the amalgam, but there is another perspective to consider about this : the caries under the AMG are most of the time arrested caries. When you put your new well fitting crown on top of the old core, there will be a good seal and the arrested carie will stay that way. Also, i am against bonding crowns, it's near impossible to get a perfectly dry field which is mandatory to get a good bond. I think GIC is the best material to cement crowns when there is no esthetic concern.
Interesting point. I do like you, find decay under the amalgam, but there is another perspective to consider about this : the caries under the AMG are most of the time arrested caries. When you put your new well fitting crown on top of the old core, there will be a good seal and the arrested carie will stay that way.
Also, i am against bonding crowns, it's near impossible to get a perfectly dry field which is mandatory to get a good bond. I think GIC is the best material to cement crowns when there is no esthetic concern.