Augmentation Procedures
When a tooth is extracted, the healing of the tooth socket
involves the jaw bone remodelling as a normal process. This results
in bone loss which can sometimes compromise the placement of dental
implants. Success in dental implant treatment is much more likely
when there is an adequate amount of bone and also the bone is in the
right anatomical position. If there is a lack of bone then an
implant is not possible. A variety of procedures are available to
increase the amount of bone prior to dental implant placement. These
procedures can be performed both under a local anaesthetic or a
general anaesthetic:-
A
Socket preservation and contouring
This procedure involves the placement of artificial bone -
Bio-oss - into the tooth socket (picture right) at the time of
the tooth extraction.
Bio-oss
is a specially prepared artificial bone in the form of granules
which convert to normal bone over a period of 3-4 months.
It is known that the placement of this material will preserve the tooth socket in readiness for a dental implant.
In most cases the granules have to be retained in the socket (see picture left) by using a membrane over the socket.
B. Sinus lift procedures
The maxillary sinus is an air-filled cavity just below the
cheekbones which is connected to the nose (diagram right).
When posterior maxillary teeth (upper back teeth) are extracted, the bone, like any other part of the jaw bone, remodels in the normal process of healing.
This can sometimes result in a lack of bone in the posterior maxilla for dental implant placement.
To increase the amount of bone in the posterior maxilla (upper back jaw), a procedure known as a sinus lift procedure is performed.
This can be done on one
(unilateral) or both sides (bilateral) of the jaw. Bilateral sinus
lifts are performed at the same time.
The procedure can be carried out under a local, or more often, a general anaesthetic.
However, even under general anaesthetic, surgery does not require an overnight stay in hospital.
The procedure lifts up a flap of gum and the sinus is
entered. Granules of Bio-oss are packed into the floor of the
sinus (diagram above) to increase the height of the bone in the posterior maxilla.
The Bio-oss granules are covered with artificial membrane (diagram right) and the gum stitched over with dissolvable stitches. Four months later, dental implants can be inserted into the posterior jaw onto which crowns and bridges can be fitted at a later date.
C. Onlay graft
In the upper front jaw (anterior maxilla) bone remodelling frequently involves the loss of the outer or lip surface of the jaw bone. This makes the placement of dental implants, particularly in the correct position, very difficult.
Onlay grafting involves the placement of bone on the outer surface of the anterior upper jaw bone. In this procedure, the patient’s own bone is preferred to provide the best contour and lip support. For small defects (a single missing tooth), bone from the lower jaw is taken and placed into the top front jaw. Where several teeth are missing, a larger piece of bone is required, usually taken from the iliac crest (hip bone).
In some circumstances, the bone requires a screw to hold it
in place during the healing process. Three to four (3-4) months
later dental implants can be placed into the bone graft (if required
the screws are removed at the time of implant placement).