More people are electing to have failing
or missing teeth replaced by dental implants. I have experienced an
increase in the number of questions related to dental implants and
scuba diving in my capacity as a dental
consultant for DAN, ScubaDoc and the Scuba Board. It is only natural
because of the confluence of both
diving and dental technologies that occurs within the mouth. Dental
implants are found where the scuba
regulator ends. Dental implants are associated the very same spaces
containing gas that must be equalized
during a dive.
This results in questions ranging from,
“How long should I wait after implant surgery before diving?” to,
“Will the pressure on the bite of my regulator affect the implants
within my mouth?”
First, here is a short history of dental implants.
There is archeological evidence that
certain early civilizations attempted to re-implant lost teeth as well
as
those made of carved wood or ivory. In the eighteen hundreds, first
gold and later, platinum implants were
being placed into the human jaw. These proved to be unsuccessful. In
1937, Strock placed the first
successful implants at Harvard University. These implants were made of
a type of surgical stainless steel
call Vitallium. This is a chrome, cobalt, molybdenum alloy commonly
used in removable partial dentures.
In 1948, Gustav Dahl reported the first subperiosteal implant. Then in
1967, Linkow, and Ralph and Harold
Roberts introduced the endosteal blade implant. Finally, in 1981, the
orthopedic surgeon, Dr. Per Ingvar
Brånemark introduced the titanium, endosteal, root form, implant.
This final type of implant is the
prototype of today’s most common dental implant. The key to the
implant’s
success is the use of titanium metal. In 1952, while Dr.
Brånemark was doing bone-healing studies on
rabbits, he inserted a small titanium plate with a lens attached into
the bone of his experimental animals.
This allowed him the peer into the bone and actually view the healing
process microscopically. At the
completion of the experiments, Dr. Brånemark attempted to remove
the titanium plate, he found that the
surrounding bone had fused to the metal. He called this fusion,
Osseointegration. Through this serendipitous
occurrence, successful dental implants and other implantable orthopedic
devices would be possible.
Obviously, in order to get an implant, one must first have surgery.
There is surgery to extract a tooth and
surgery to insert the implant. It might be necessary to graft bone into
sockets to create a site suitable for the
future implant and it might also be necessary to fill in part of the
maxillary sinuses to give a patient enough
vertical bone height to support implants in the upper back part of the
mouth. Surgery is needed to increase
the bone height in jaws that have receded away and there may even be
surgery at remote sites like the ileac
crest to harvest large quantities of bone to build up the jaws. It is
the surgery, the requisite healing period,
and the prosthetics that affect patients who wish to scuba dive.
Generally, if there is a missing tooth
and there are appropriate bone dimensions, a specially sized hole is
made into the bone using precisely sized drills. Then the implant is
threaded into it. A cover screw or a
healing abutment is then screwed into the “top” of the implant. The
implant is then allowed to
osseointegrated for a period of between 4 to 6 months.
A cover screw is used when the implant is to be covered with a flap of
skin during the healing period. The
implant is then surgically re-exposed following the healing period and
parts are then attached to the exposed
implant to make it possible to restore. To avoid this re-exposure or
second stage surgery, most surgeons are
now using healing abutments that purposely project through the gums
during the healing period. This
abutment is simply unscrewed by the prosthedontist when the implant is
ready to be restored. The
appropriate parts are then added to render the implant restorable.
During the osseointegration period it is necessary to avoid anything
that could apply pressure to the skin
over the implant and cover screw or the healing abutment. It is
possible for such pressure to create small
movements or micro-movement of the implant. Such movements can disrupt
the osseointegration process.
Movements greater than 50-150 microns are sufficient to result in
implant failure.
If the bone dimensions are not adequate, then bone-grafting procedures
are utilized to increase the height
and width of the implant site. Natural bone can be obtained from
shavings from the preparation of the
implant surgical site, other parts of the mouth or even other parts of
the body. This natural bone may be
mixed with human bone from other sources, bone from other animals or
even artificial “bone.” Whatever
the source, this bone is grafted into the surgical sites both to
stabilize the implant and to create an adequate
height and volume of bone to contain the implant.
When a tooth is extracted, the site is
usually allowed to heal from 3 to 6 months. Then the site is re-entered,
the implant is placed, and the appropriate osseointegration period is
allowed to occur. Many surgeons like
to re-enter the site at about 3 months. There is maximum osteoid growth
potential then which can be
harnessed for osseointegration. Under the right conditions, an implant
can actually be inserted into the
extraction site on the same visit. This immediate implant protocol
cannot be used for all extraction sites.
When immediate implant placement can be used, the extraction site
healing period is eliminated and the
patient can have the restoration months sooner.
Diving should be avoided for as long as it takes to avoid complications
associated with revascularization,
stabilization of the implant, oral and sinus cavity pressure changes,
ability of the patient to hold a regulator
in their mouth, medications for pain or infection.
No hard and fast recommendations related to oral surgery and scuba
diving has been developed. These
recommendations are often related to wound healing physiology.
Generally, the more complicated the
surgery the longer the wait. Surgical complications will add to this
time, as can any underlying medical
conditions, tobacco use and alcohol consumption.
Gas exchange is partially a function of the vasculature of the local
tissues. Simple extraction sites quickly
develop a blood supply. Similarly, extraction socket grafting (socket
preservation) also revascularizes
rapidly. Diving following a simple extraction usually requires a 1—2
week recuperation time.
Bone grafting procedures and sinus surgery are more complex and will
require a longer waiting period. The
larger the graft site, the longer the wait. Six weeks to two months is
a more likely time period to avoid
diving. Even three months can be appropriate.
There are no documented medical
guidelines regarding scuba diving and oral surgical recuperation
periods!
Patients will heal at their own rate no matter what “rules” we want to
apply. This period might have to be
revised according to how YOU respond to the surgery. Your surgeon
should determine the appropriate time
period. Even if your surgeon doesn’t dive, follow his advice. He is
motivated by your welfare rather than
your eagerness to return to diving. Don’t wait until after your surgery
to discuss with your doctor the nonrefundable
reservations made months ago for a dive vacation on a live-aboard to
Australia in two weeks.
You won’t like what he is going to tell you!
The quantity and quality of the underlying bone also affects
implant/diving waiting periods. Some people
have very hard, dense bone and others have soft, spongy bone. This
affects the primary stability of the
implant inserted into it. Implants placed into hard dense bone are less
susceptible to micro-movements
already described. The opposite is true for soft, spongy bone. Newly
inserted implants are most vulnerable
to movement within the first 2-4 weeks following surgery. The implants
actually get looser within the
surgical site before they begin to stabilize. Scuba diving must be
avoided during the initial stages of
osseointegration. A minimum of 5 weeks to two months is needed to just
to render the implant stable.
Longer times would be appropriate if substantial bone grafting has been
done.
Diving too soon and applying pressure to the implant, no matter how
slight, could cause sufficient micromovement
that could lead to implant failure. If the regulator’s bite tabs are
over the implant site, biting
forces can be applied directly or indirectly to the healing implant.
This may even occur to implants that
appear to be out of bite. Applying pressure to teeth, flexes the jaws
and this too, is a type of micromovement.
Some doctors will recommend avoiding anything that causes
micro-movement for at least 6 months. It can
actually take up to one year for complete bone healing to occur in an
implant site. While diving sooner than
one year may not cause a problem, it will be up to you and your dentist
or oral surgeon to determine your
own risk tolerance.
Traditionally, an implant is placed and then allowed to integrate for a
period of 4-6 months. Following this
implant healing period (osseointegration), the final prosthesis, be it
an implant supported crown, fixed
bridge or fixed detachable denture is then fabricated. During this
healing period, the patient would either
wear nothing or some sort of temporary prosthesis that is generally not
attached to the healing implant(s)
such as a temporary removable partial denture. In the last several
years however, protocols have been
developed to help patients get into their final prostheses more quickly.
It is now possible to fabricate prostheses that are either put into use
immediately or delayed only a few
weeks. Generally, these immediate or early protocols are used when high
initial stability of the implant can
be achieved at the time the implant is placed. It is extremely
important that excessive forces of abnormal
magnitude or direction do not disturb the underlying implants.
Just because your surgeon and dentist has allowed you to wear an
implant supported device sooner, it would
probably NOT be wise to apply the additional biting load of a scuba
regulator to the healing implants and
the overlying temporary device. Again, micro-movement may occur and any
temporary devices used which
will usually be made of plastic and anchored with some sort of
temporary cement or temporary screw. It
would be safer to be more conservative and delay scuba diving until the
final restorations are in place.
Once dental implants are fully osseointegrated and the final prostheses
have been placed, there is nothing
inherent to scuba diving that would pose a threat to either the
implants or the restorations. The spaces
engineered into the implants to hold the overlying screws, abutments
and prostheses are small and are
completely contained within the titanium structure. There is no air
space communication between the
implants and the surrounding tissues. The implant structure is strong
enough to withstand any pressure
differentials that might occur if small amounts of gas were to migrate
into these engineered spaces.
The overlying implant prosthetics can exhibit some of the same,
extremely rare dental problems reported
with scuba diving. Breakage of porcelain or cementation failures can
occur and the use of implants affords
no special ability of the overlying dental restorations to resist such
failures.
Some implant-supported devices are cemented and as such, a cementation
failure due to pressure changes is
possible. This is a rare occurrence. Some dentists prefer to use a
weaker, temporary cement under the final,
permanent implant crowns and bridges. This allows for future removal of
the restoration if deemed
necessary. Other dentists treat the cementation to implants just like
teeth and use permanent cement. Their
philosophy is, “If I wasn’t worried about permanent cement for teeth,
why worry about it for implants?”
It would be wise to know whether your dentist has used temporary or
permanent cement under your implant
restorations. The likelihood of even the temporarily cemented
prosthesis coming off is rare but you should
be aware that it could become a problem.
Generally, if you have an implant restoration for over a year, in all
likelihood, it will not fail as a result of a
loss of osseointegration. However, there are other failure modes that
can occur that are unrelated to the
surgery, placement and healing of the implants. There are rare
instances of implant breakage, abutment
breakage, or retaining screw failures. This is usually associated with
a very strong bite, trauma, poor
treatment planning or a materials failure. Diving would not be the
proximate cause for such failures.
The increased use of dental implants makes it more than likely that
some scuba divers will be participating
with these devices. Scuba diving is not contraindicated for people who
have had successfully healed and
restored implants. There are certain aspects of dental implant
procedures and restorations that would
temporarily limit a diver’s participation in the sport. A thorough
discussion with you oral surgeon and
dentist should make your implants successful and your diving safe.
*Permission to print from Dr. Stein and DAN. Dr. Stein is an excellent
source of information concerning
dental problems as they relate to scuba diving. He is a valued
consultant for Diving Medicine Online
(scubadoc).