it varies from school to school. in umdnj we have certain "junior year" requirements that must be done in the year, and some requirements can carry over. for examples, we have to do 12 units of removable (6 rpd's/ 6 Full dentures)...but for junior year we have to have a certain amount of points done (each denture is worth a certain number of points) in order to move onto senior year...19 units fixed total, 6 for junior year....by graduation, 6 scaling/root planings total, 8 root canals, lots of operative, minimum 20 extractions, 5 nitrous admins, etc