Mandibular endosseous implant interventions 337

Fig. 9-6. A round bur is drilled through the crest of the ridge and into the underlying alveolar bone. (From Linkow, L. I.: The radiographic role in endosseous implant interventions, Chron. Omaha Dent. Soc. 29 [10]: 304-311, 1966.)

Fig. 9-7. An x-ray revealing two No. 6 round burs parallel to each other. (From Linkow, L. I.: The radiographic role in endosseous implant interventions, Chron. Omaha Dent. Soc. 29 [101:304-311, 1966.)

margins and occlusal relationships were checked and adjusted as necessary (Fig. 9-5). The tissue-bearing surface of the temporary acrylic splint was hollowed out. The splint was tried in position and ground into proper occlusion.

To insert the first vent-plant, a No. 6 round bur, placed in a slow running contra-angle with a water spray attachment, was positioned over the center of the alveolar crest and drilled directly through the mucoperiosteum into the underlying osseous tissues until stopped by the built-in "stop guard" on the bur shaft. The bur was left in position (Fig. 9-6) and radiographed. The x-ray reveals its proximity to the mandibular canal and its degree of parallelism to the previously prepared natural tooth abutments.

Leaving the first bur in the alveolus as a parallel guide, a second round bur was drilled into the bone about 4 mm. behind the first and radiographed (Fig. 9-7).

Leaving one of the round burs in position, the other was removed, and a helical bone bur was inserted through its vacated hole. This was driven deeper into the bone, making sure that it was parallel both mesiodistally and buccolingually with the pre-pared teeth and with the extended shaft of the round bur (Fig. 9-8). Another x-ray was taken to deter-mine the depth of the helical bur, its proximity to the mandibular canal, and its degree of parallelism with the prepared teeth and round bur shaft. Leaving the helical bur in the bone as a parallel guide, the remaining round bur was removed and the second helical bur driven into its site parallel to the shaft of the first helical bur and deeper than the hole created

Fig. 9-8. Two helical burs are then drilled into the bone deeper than the previously removed round burs. (From Linkow, L. I.: The radiographic role in endosseous implant interventions, Chron. Omaha Dent. Soc. 29[10]:304-311, 1966.)

Fig. 9-9. An x-ray showing both helical burs in position. (From Linkow, L. I.: The radiographic role in endosseous implant interventions, Chron. Omaha Dent. Soc. 29 [10]: 304-311, 1966.)