ORAL REHABILITATION
Figure 2 Postoperative panoramic x-ray
Figure 1 Postoperative panoramic x-ray
failure rates have been experienced in situations
with inadequate bone volume and density in
edentulous patients (4, 15, 16).
These problems reduce the patient’s compliance
and may lead to refusal of treatment. Therefore,
during the last two decades the placement of
dental implants in the zygomatic bone process
has become a proposed alternative to bone
augmentation procedures.
The clinical procedure for placement of zygomatic
implants was first described by Brånemark (Nobel
Biocare, Göteborg, Sweden) to provide the
clinician with an alternative to grafting procedures.
After their initial clinical use in patients with
maxillary resection for malignant diseases (17), the
indication of zygomatic implants was expanded
to completely edentulous patients with severe
maxillary atrophy (18). The bone of the zygomatic
arch was used for anchorage of a long implant
and, together with conventional implants, could
be used as an anchor for epistheses, prosthesis
and/or obturators (19).
In clinical practice, zygomatic implants have been
used in association to conventional implants or
alone. The first protocol proposed involved the
placement of a minimum of 2 premaxillary implants
in the canine position, or ideally 4 premaxillary
implants in the canine and the central incisor
positions, allowing for the fabrication of fixed
hybrid prostheses (20). After that, Bothur et all. (21)
proposed the use of prosthesis full supported by
multiple zygomatic implants (Fig. 1-2).
The technique provides many patients with a
Figure 3 The mixed technique
70
restored function, improving their esthetic and
social life. Bedrossian (22) distinguished three
zones in the upper maxilla to provi de a decisional
flowchart: zone 1, the premaxilla: zone 2, the
premolar area: zone 3, the molar area (Table 1).
In case of an adequate bone in zone 1 and
bilateral lack of bone in zones 2 and 3, two to
four conventional implants are distribuited in the
anterior maxilla plus one zygomatic implant on each
premolar/molar side. This is the so-called mixed
technique (Fig. 3). Conventional implants placed
in the premaxilla probably reduce the load applied
to the zygomatic implants and the effectiveness of
this mixed rehabilitation is dependent on a rigid
connection between implants (18). Particularly,
there is a significant biomechanical disadvantage
regarding the long lever arm and the small amount
of bone integration and the biomechanics of these
implants could be improved by inserting angled
implants connected to conventional fixtures (23)
and reducing the distal cantilever (24) . Moreover
the angle head of the zygomatic implant is
designed to allow the placement of the prosthesis
at 45° to the long axis of the implant, minimizing
the lever effect (20).
Instead, in case of lack of bone in all three zones of
the maxilla, four zygomatic implants can be used
for the rehabilitation. In this option, the “QUAD
technique”, zygomatic implants are used alone and
placed in an arch form to counteract the bending
forces (25). Four implants, two on each side, can
restore the entire dental arch: the anterior ones
rehabilitate the incisor-canine region, whereas
Figure 4 The “QUAD” technique
STOMA.EDUJ (2015) 2 (1)