Intraboney (vertical) defects are defects within the bone right adjacent to the tooth structure. If an intraboney defect has three walls, and a narrow angle of the defect exists, there is a higher success rate for regeneration. It is also possible to regenerate defects in furcations. Guided tissue regeneration (GTR) is a technique whereby cell exclusion principle is used to allow bone regeneration to take place with less competition from other fast growing cells such as epithelium and connective tissue.

An intraboney defect on the mesial of tooth # 31 is treated with GTR with a very positive result.