I have 6 upper front dental crowns need to be replaced with full ceramic crowns due to black lines. Should I have all 6 of them (all individual crowns, not connected) replaced in one batch or done one by one, or two/three crowns each time? In terms of the difficulty for dentists and labs, which is the least challenging way? I am concerning about this as the more complicated the treatment procedure, the more chances of problems occurring to my teeth in the future, such as occlusion problems and possible infection. Also, since most of these teeth are still vital, will the procedure of crown removal disturb the abutment teeth and cause pain in the future? What is the chance of damaging the abutment teeth during the crown removal?