Bone Grafts
There are times when it is necessary to perform
bone grafting or bone regeneration in conjunction with an implant.
This is necessary to ensure that there is an adequate amount of
bone to anchor the implant so that it can withstand the forces that
it is subjected to. The following are situations where bone regeneration
may be required.
Extraction
If at the time of extraction there has been a
lot of bone loss, it might be necessary to place a bone graft. In
these situations there has usually been some type of infection that
has destroyed the bone that held the tooth in place. The infection
is cleaned out and the bone graft is placed into the site where
the tooth was (the extraction socket). Sometimes a membrane is placed
over the area to hold the graft in place and improve the areas of
regeneration.
Ridge Augmentation
If it has been a long time since the tooth has
been extracted or if there was a lot of bone loss at the time of
infection, the remaining bone might be far too thin to hold an implant.
In these situations it might be necessary to do bone grafting prior
to placing the implant a process termed ridge augmentation. In these
instances, the bone graft is placed, usually covered with a membrane
and left to sit for six months. After six months, the implant can
be placed.
Implants: Guided bone regeneration
Sometimes when an implant is placed there may
not be enough bone to cover the whole implant. If the implant is
stable and held in place with bone, we can perform a bone graft
to try and cover up the part of the implant that is not covered
by bone. In these instances, the implant is covered with bone and
a membrane. The gum is then closed over the area and the implant
is uncovered 6 months later.
Sinus elevation procedures
The maxillary sinus is an air filled space in
the upper jaw (the maxilla). As we age, and when we lose teeth,
the sinus can increase in size. When this happens, it tends to grow
down and take the place of bone that used to hold the teeth in place.
If a sinus grows too large at the expense of bone, it might prevent
us from placing implants that are long enough to withstand the forces
to which they will be subjected. In these situations, we consider
something called a sinus elevation procedure. This is often done
at the same time as placing the implant(s). During this procedure,
a bone graft is placed into the sinus in the area where the implants
will be placed. This bone will then help to anchor the implants.
Usually the procedure does not result in much more pain or sinus
symptoms.
Type of Bone Grafts
The most common question when talking about bone
grafts is: Where does the bone come from? Most forms of bone grafts
work well and the decision is often a personal one for the patient
to make. It is important to discuss all relevant issues with your
dentist prior to making this decision. Basically there are a few
different options.
Bone from yourself.
In most cases, bone can be taken from sites within
a patient’s own mouth. The most common places to get the bone
are sites where teeth are missing such as the third molar sites,
the side of the lower jaw or the chin region. An incision is made
to retrieve the bone and the site is then sutured.
Bone from human donors.
Bone can be obtained from human donors through
bone banks. The donors are screened and the bone is put through
a sterilization process. To date, there is no evidence of disease
being transmitted through a bone graft. This type of bone graft
is easier to use as there is no need for a second surgical site.
Other types of grafts
Other types of grafting material may be used.
These include collagen taken from cows and artificial substances
based on a material not unlike glass. Although these materials will
provide bulk in the area, they usually do not resorb and remain
in the mouth for a very long time. Other bone grafts using human
bone tend to be replaced by the patient’s own bone over time.
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