Intraosseous eruption involves the formation of root of a tooth which allows the tooth to being eruption from the bone. This phase precedes the Supraosseous Eruption phase which consists of Infragingival eruption and Supragingival Eruption. Both the Intraosseous eruption and Supraosseous eruption are part of an eruption phase called Prefunctional eruption.
References
Intraosseous eruption Wikipedia(Text) CC BY-SA