Atrophic Anterior Mandible
In the atrophic mandible (l.e., less than ‘8 mm of vertical height), the shortest implant may be longer’ than the available bone. Implants may be placed by purposefully perforating the inferior cortex. This’ may decrease the crown-to-root ratio or increase th, risk of “fracture .’ Recent studies have shown that afte. restoration ‘ofthe. atrophic mandible with an entirely implant-supported prosthesis, bone height and density increase, presumably as a result of the functional stresses that result horn the
prosthesis. Therefore an effective approach in the atrophic’ mandible is to place five implants, leaving 2 .to 3 rnm above the height of the residual bone. An entirely implantsupported hybrid prosthesis is then fabricated. Alternatively the transmandibular implant (TMI) has also been shown to be effectIve in the very atrophic mandible, with’ similar remodeling and formation of new bone. Either of these techniques may be considered in ·the atrophic mandible where 6 mm or more of bone height is’ found If the bone height is less than 6 mrn, augmentation of the .bony height in this area with autogenous gratis may be necessary. Autogenous grafts onlayed onto the residual ridge will undergo resorption if conventional dentures are placed but are generally maintained well if an implant-borne prosthesis is placed.