The following are some examples of Class II malocclusion (dental Class II) or skeletal Class II or both. Some people use the layperson term "overderbite" to describe this condition, but the correct term is actually excessive overjet.
Case 1: 14 yr-old male
For problems similar to this case, most orthodontists would require extraction of premolars. But this case demnonstrates that it is possible to treat without any extraction - by using TADS (temporary anchorage devices).
Fig. 1 View showing ovejet (initial)

Fig. 2 View showing progress (1 year), no extraction