The transalveolar sinus elevation,
often called closed or also osteotome technique
is based on a technique developed by Summers
and published in the early 90s.
Summers used a set of sharp osteotomes
of increasing diameter in order to
create a controlled fracture of the sinus floor and
consequently push bone debris from the sides of the osteotomy
to an apical direction,
creating the space necessary under the sinus membrane
in order to place implants.
Ever since the publication of Summers however,
there has been so many modifications and changes
introduced to the transalveolar technique
that today it is difficult to identify a single standard.
The basic principle however remains the same:
the creation of a controlled fracture of the sinus floor
and the creation of a space under the membrane
with or without the use of grafting material.
There is a wide variety of osteotomes available today,
either as generic instruments
or specific to certain systems and techniques.
Nevertheless, some critical elements of osteotomes have to do with
the type of the edge and the shape
of the engaging part of the instrument.
A concave edge is more aggressive
and will concentrate more force on a smaller surface.
It is indicated in cases of harder cortical bone,
but will require precise control.
When using this type of instrument
after the preparation of the osteotomy,
the force is gathered at the margins of the osteotomy
and often pushes the fractured segment of the sinus floor
to an apical direction.
A convex edge of the osteotome is less
aggressive and safer to use in cases of softer bone.
Such an edge is more likely to create
a less defined dome-like fracture of the sinus floor
and it is usually safer than the concave edge.
Furthermore, the engaging part of the osteotome
can be either parallel or tapered.
A tapered instrument will condense the bone laterally
at the same time as advancing
in an apical direction.
This can be beneficial in cases of soft spongious bone.
Now let's take a quick overview of
how this could be applied in a typical patient case.
Our patient is going to receive two implants
in a segment of his posterior maxilla.
After the three-dimensional radiographic assessment,
we have calculated that
the bone height to the sinus floor
is 6 and 4 mm, respectively.
Let's see the implant in the 6 mm site first.
Here we are looking to generate
two more millimetres from the sinus.
To start with, we identify the place of the osteotomy
and then, we continue preparing the osteotomy
stopping short of 1 mm to the sinus.
That is drilling for 5 mm.
After the final drill, we place the osteotome.
Gentle knocking with the mullet will be enough to create
a small, controlled fracture of the sinus floor
and give us two additional millimetres
for implant placement.
Let's now move to the 4 mm site.
In this case, we need to elevate the sinus floor
for another 4 mm.
To achieve this without perforating the membrane,
we often have to use some grafting material.
Again, we mark the osteotomy and
continue preparing to the last drill,
stopping short of 1 mm from the sinus floor.
After the final drill, we place again the
osteotome and create a controlled fracture,
adding another 1 to 2 mm to our preparation length.
We would then use our grafting material
to gently elevate the sinus floor
for the last remaining 2 mm.
Attention!
At this stage, please remember the gentleman
who just popped out!
This is the famous Renaissance anatomist Antonio Valsalva
and I'm sure you're all familiar with
the Valsalva manoeuvre!
Remember, the sinus membrane is like a balloon
with only one narrow opening high at the ostium.
If this opening gets blocked,
and the sinus can no longer drain through the nose,
chronic sinusitis and major problems can follow.
Loose biomaterial in the sinus can
quickly accumulate and block the ostium.
It is crucial therefore to ensure that the membrane is intact
before you place any biomaterials in the sinus.
The transalveolar sinus elevation technique
is widely practised today and most research
points to a high survival rate of the implants placed this way.
Prevalence of membrane perforation is reported around 4%,
while other complications include
tinnitus and low prevalence of nausea,
post operative infections of the surgical wound or the sinus.
Nevertheless, it is a technique that allows no visual inspection
and no margin for errors.
Rare but dangerous complications have also been reported,
such as the case of a patient with a severe bleeding
which required hospitalisation.
As with everything, careful patient selection and plan
as well as good preparation
and education of the operator is the key to success.