572 Theories and techniques of oral implantology

tions. From a physical point of view alone, a full arch horseshoe type universal subperiosteal implant is more stable than unilateral types, since it utilizes the symphysis and genial tubercles and also extends to both sides of the arch, which increases stability and primary retention of the implant. An added safety gap is included in the universal implant in that if ever the anterior teeth should have to be extracted, the

Fig. 12-107. A preoperative photograph of a disheartened patient.

patient still can retain a full arch implant denture without any further surgery.

MAXILLARY TOROPLANTS

Maxillae exhibiting very little or no bone below the maxillary sinus and nasal vestibulum along with the clinical appearance of extremely flat ridges have always presented problems in the fabrication of well-fitting dentures. Patients with this condition cannot obtain dentures that are stable and retentive enough to satisfy them.

The introduction of mucosal inserts is certainly not advisable, for they might be pushed into the superficially located maxillary sinus. Subperiosteal maxillary implants would also fail in such situations, since the metal struts of the substructure crossing over the atrophied alveolar crest would eventually sink into the antrum and nasal cavities.

— Since the hard palate is the only area in the maxilla that is of a permanent type bone, while all the rest of the maxillary osseous structures are of a transient type, Linkow decided to utilize only the hard palate   and he thus created the toroplant.

A preoperative photograph of the patient as well as a preoperative Panorex of his edentulous jaws are seen (Figs. 12-107 and 12-108).

Clinically, the soft tissues covering the atrophied maxillary alveolar ridge created a very flat appearance, making it extremely difficult for an adequately fitting conventional denture (Fig. 12-109). A sub-

Fig. 12-108. A preoperative Panorex radiograph of both arches.