[A comparison of two methods for pre-operative radiographic examination in treatment with oral implants in the anterior mandibular area].

Insertion of osseointegrated implants in the anterior mandibular region for retaining a removable denture represents a treatment, which is cheap for the patient and surgically uncomplicated. Bone height measures from two radiographic examinations 1) panoramic radiographs and 2) lateral tangential views, were compared. Radiographs from 20 patients were analyzed. The vertical height of the mandible was measured in the midline as well as in the cuspid region on the panoramic radiographs and the tangential views ("maximum" bone heights). The mean maximum bone heights were higher on tangential views in both regions. On the tangential views the inclinations of the future implants were estimated and the part of the alveolar ridge having a width less than 5 mm, which is the minimum width for housing an implant, was compiled. The resulting height ("effective bone height") was calculated. In 10% of the cases the effective bone height was equal to the maximum height, and in 90% it was smaller. The over-estimation varied between 0 mm and 15.3 mm. It is concluded that panoramic radiographs are unreliable for evaluating bone height in planning insertion of oral implants in the anterior mandibular region. They give no information about form and width of the bone. Tangential views reveal the true morphology of the mandible as seen in a cross-section, and offer an opportunity for calculating the effective bone height at disposal for oral implants.