4 Theories and techniques of oral implantology

Fig. 1-4. A No. 6 round bur with "stop collar" is used n a slow running contra-angle to penetrate the fibromucosa old bone.d   

Fig. 1-5. The radiograph reveals the round bur in bone.

Fig. 1-6. Two round burs are seen in the correct positions--parallel to each other and to the anterior abutment preparations.

and all occlusal adjustments are made. After refer-ring to the original x-ray films and carefully determining the optimum location and depth of the implants, the procedures for their insertion begin.

Using a No. 6 round bur or a spear-point bur in a slow-speed contra-angle with a water spray attachment (Fig. 1-4), the crest of the alveolar ridge is penetrated to a depth of 5 or 6 mm. The bur is then released from the contra-angle and allowed to remain in the bone. An x-ray is taken (Fig. 1-5).

With the first round bur still in position to serve as a parallel guide, a second No. 6 round bur is driven into the alveolar bone slightly posterior to the first one. The contra-angle is then detached, and another roentgenogram is taken to determine the positions of the two burs and the anterior teeth (Fig. 1-6).

One of the two round burs is removed, and the other is left in position as a parallel guide. A heavy-gauge helical bone bur is set into the contra-angle

Fig. 1-7. A helical bur is driven deeper than the preceding round bur and should be parallel to the remaining round

hur.

and inserted into the site from which the round bur was removed. This bur should penetrate slightly deeper than the round bur. Another roentgenogram is then obtained of the area (Fig. 1-7). If the film shows that the helical bur is not parallel to the round bur, adjustment is made as the bone is penetrated a little deeper. When the first helical bur is in position, the second round bur is extracted and replaced by a second helical bone bur, which in turn is driven the desired distance into the alveolar bone. After x-ray films have demonstrated that the two bone burs are parallel to each other and to the pre-pared abutment teeth (Fig. 1-8), one of them is withdrawn, leaving the other in place as a guide.

At this point, a new instrument, the dental ratchet, is brought into use (Fig. 1-9) . One of the two smaller taps is locked into the ratchet and inserted into the prepared hole, whose diameter is slightly smaller than that of the spiral portion of the implant. The operator turns the ratchet clockwise with