which type of teeth occur only once in a life time i.e. monophydont in human beings...??

In human beings, dentition is diphyodont i.e they have two sets of teeth. The first one is set of milk teeth (temporory teeth) which are found in the children and the second one is the set of permanent teeth which are found in the adults.

Milk teeth if break can come again but if permanent teeth get broken once they will not come back again.