In this paper, we describle a model that relies on the following assumption; ontology negotiation and creation is necessary to make knowledge sharing and KM successful through communication. We mostly focus on the modifying process, i.e. dialogue, and we show a dynamic modification of agents knowledge bases could occur through messages exchanges, messages being knowledge chunks to be mapped with agents KB. Dialogue takes account of both success and failure in mapping. We show that the same process helps repair its own anomalies. We describe an architecture for agents knowledge exchange through dialogue. Last we conclude about the benefits of introducing dialogue features in knowledge management.