256 Theories and techniques of oral implantology

lary tuberosity distal to the most posterior extent of the low-flaring maxillary sinus (Fig. 6-66). In these areas only the blade implant can be employed.

When the sinus floor drops down to the alveolar crest but remains small anteroposteriorly (Fig. 6-67), the operator may place implants anterior and posterior to the sinus. He may use blades or tripodial or quadrapodial pin type implants stabilized with the added support of a scalloped template.

Certain situations are so limited that the opera-

tor has little choice. A low-flaring sinus with very little bone depth on either side of it must be circumvented by pin implants or B-P blades (Fig. 6-68) .

Whether or not a full arch fixed partial denture should tie in the remaining anterior teeth with the implants depends upon the condition of the teeth and their supporting bone. Factors to be considered are the amount of bone support, periodontal condition, individual tooth direction and location in the arch, and opposing jaw dentition. Including these

Fig. 6-70. Uneven resorption of the posterior areas in this mandible limits the choice of endosseous implants in the shallower side to a blade.

Fig. 6-71. When little or no bone exists posteriorly above the mandibular canal, a subperiosteal implant must be used.