Residual ridge form has been described and classified by Cawood and Howell7 as follows:• Class I—dentate• Class II—post-extraction• Class III—convex ridge form, with adequate height and width of alveolar Process• Class IV—knife-edge form with adequate height but inadequate width of alveolar process• Class V—flat-ridge form with loss of alveolar process• Class VI—loss of basal bone that may be extensive but follows no predictable pattern