Clean and check the crown. If the crown is mostly hollow, you can attempt to re-cement it at home if you feel confident to do so.
Remove any debris from the crown, you can use something like the tip of a paperclip to scrape the old cement away. Clean your teeth thoroughly. All debris must be removed from both the crown and the tooth for it to seat properly.
Check the crown fits without cement. Check that the bites feel correct, if the tooth feels too tall, it is not fitted correctly, double check the debris. NEVER force a crown or post onto or into your teeth, this can cause a root fracture.
Crowns should be replaced using a dental cement from a pharmacy like Recapit. Do not use SUPERGLUE or FIXADENT to fit your crown.
Once you have practiced placing the crown, dry the tooth and crown, mix the cement as instructed on the packet and fill the crown. Place the crown directly onto the tooth. Bite firmly to press into place.
Remove any extra cement with a toothpick and floss between your teeth to make sure they do not stick together.