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150 Osseointegration and Dental Implants
Figure 7.13. Maxillary osteotomy with bone graft
attached to the sinus recesses and nasal cavity by use of
wires.
procedure can be done either as a one-stage
or two-stage procedure. In a one-stage procedure
implants are placed simultaneously with
the bone graft material (Kahnberg et al. 2001;
Keller et al. 1999; Wannfors et al. 2000).
With one-stage protocol the bone tissue
below the sinus cavity has to have a certain
volume—at least 6–7 mm if not more—to stabilize
the implants, otherwise there may be
mobility in the graft material with the
implants, initiating an infl ammatory process
with subsequent loss of both bone graft and
implants.
The two-stage procedure with grafting
fi rst, then allowing for healing for about 4
months, and then implant placement is the
most common (Kahnberg and Vannas-
Löfqvist 2008; Krekmanov and Heimdahl
2000). This procedure is successful according
to most publications, with implant survival
and success rates between 85% and 100%.
The complication that may arise is, of course,
when there is a perforation of the sinus membrane.
If the perforation is limited in size (3–
4 mm) it is normally possible to cover it with
a collagen membrane and still succeed with
the operation. The sinus cavity is a closed
space with drainage only through the osteum,
Figure 7.14. The alveolar crest reconstructed with bone
graft.
which is why infections can easily be established
in sinus lifting procedures. Local sinus
lifting can be done when a single tooth is
missing in the posterior maxilla and the sinus
cavity has extended down in to the alveolar
process. For a local sinus lift we recommend
using the implant as a tent pin to hold
the sinus membrane, reserving the space
around the implant for bone fi lling (Figs.
7.14–7.18).
The use of biomaterial instead of autologous
bone is becoming increasingly popular.
Bio-Oss and similar products function very
well. The only criticism is that healing time is
extended to almost 2–3 times that of natural
bone. With the use of zygoma fi xtures in
resorbed maxillary cases, there are indications
for use of this kind of implant. Zygoma
implants should preferably be used in edentulous
cases with available bone in the anterior
region, for placement of three to four
conventional implants. A combination of two
zygoma implants and two to three conventional
implants has a good success and implant
survival rate (97%) (Kahnberg et al. 2007).
However, the weak points of zygoma implants
are the positioning of the implant from a
prosthetic point of view and the passage
through the alveolar process into the sinus