I have a dental post implant with a crown. The dentist used a temp cement and the crown came out last night.

If the crown is not a front tooth I would suggest leaving off the crown until your appointment. If it is a front tooth try the crown in carefully. Once you have determined which way the crown is inserted place a small amount of cement in it and push to place. It is important to get the crown correctly in position otherwise you risk breaking the crown or abutment. Good luck.