According to Atwood residual ridge classiﬁcation order V denotes:
Order I – Pre-extraction-alveolus bearing tooth
Order II – Post-extraction-alveolus after extraction
Order III – High, well rounded-high alveolar process
Order IV – Knife-edge-High, narrow alveolar process
Order V – Low, well-rounded-rounded flat alveolar process
Order VI – Depressed-concave flat alveolar process.
High well-rounded ridge
Low well-rounded ridge
Knife-edge ridge
Depressed ridge