For implants that are to be placed in the mandible, the distance from the edentulous alveolar crest to the upper border of the inferior alveolar canal should be assessed from cross-sectional tomographic radiographs.
The safety zone between the tip of the implant and the border of the canal should be at least 1-2 mm. Patients with compromised vertical bone dimension can sometimes be treated by placing multiple shorter implants of optimal width followed by splinting the prosthetic crowns together during the restorative phase of therapy.
The position of the mental formen should be identified and located when implant surgeries in the premolar and molar areas of the mandible are performed. In some situations a loop of the nerve can be found to extend mesially.
In one report the anterior loop of the mental neurovascular bundle extended mesially from 1.1 - 3.3 mm and a safety zone of 4 mm was recommended to avoid damaging the nerve during implant placement (Kuzmanovic et al.2003)
When placing an implant in the anterior part of the maxilla the size and location of the incisive papilla need to be determined. In addition, it must be established if there is enough bone in the area to place an implant or if the area needs to be grafted.
Anatomic concavities are frequently found on the lingual side of the mandible. It is important to avoid perforating the lingual plate during preparation of the implant site since perforations in this location can result in extensive and even life-threatening bleeding (Bruggenkate et al. 1993)
A safe way of performing surgery in this area is to reflect a lingual flap at least to a level corresponding to the length of the implant to be placed.