There may be two kind of temporary restorations that are commonly done in the clinic:  the temporary crown which covers tooth while your permanent crowns are being made by dentists, and the temporary fillings which are placed on tooth when it is not yet time to have the permanent fillings (this usually is done during mid phase of root canal treatment or when the cavity is very deep).

When temporary crown falls off, this is not exactly a dental emergency but it may feel a little uncomfortable. Wash the crown first, dry with a clean tissue. Fit it in to tooth to make sure it still fits. If it fits, you may put a small amount of Vaseline or dental adhesives inside the crown and placed it back to the tooth. Call your dentist and let him know what happened and make an appointment for reinstalling the temporary crown if the permanent crowns are not yet available. Avoid biting on that area.

For temporary fillings, there are usually no substitutes to replace the fillings at home. It is best to call your dentists as soon as possible and do not use the involved tooth in eating until you see your dentist to avoid fractures and cracks.

(Always Seek Professional Help)