Recommendation: Before a new crown is fabricated for a tooth that has had a root canal, making sure that the root canal is asymptomatic, no periapical lesions, and the root canal itself is of good quality. Additionally, all silver cone root canals should be retreated before new crowns are made.
This is an example of what I found in a lower first molar.
Pre Op - with Silver Points
Photo of ten silver points removed from tooth #30
Please note how corroded each point is.
Post Op - Root canal completed with gutta percha
(I can only speculate as to what the distal overhang is on the crown.)