Hello packets are to keep neighbour establishments, OSPF uses Link State Advertisements ( LSA`s ) to communicate changes.
When OSPF first starts up is uses Hello to find its neighbours, then uses DBD ( database descriptior updates ) to describe their databases, then LSA for Link changes etc.
LEEroy
MCNE6,CCNA2,3/4 CCNP,CWNA,CCSA,Project+