1. You may remember that your
first denture fit fairly tightly after it was first made, and improved your
facial appearance by improving your smile. For many of you, however, over the
course of a number of years, the dentures slowly disappeared under your lip,
and your upper and lower dentures began to fit together differently bringing
your lower jaw forward, and in some cases making it possible to bite only on
the front denture teeth.
This happens because the bone that used to support the
dentures is slowly reabsorbed by the body allowing the
top denture to sit higher and higher under the top lip, and the lower to to
drift ever lower below the bottom lip reducing the distance between the nose
and the tip of the chin. If you allow this condition to persist for too
long, the shape of the face actually changes to accommodate the new
conditions.
You begin to notice deep diagonal lines forming between the
corners of the lips and the chin. The lips flatten, and the mouth starts
to resemble a thin "slit".
The muscles that allow you
to chew shorten permanently, and even if the dentist tries hard to
build new dentures that restore the length of your face, and the shape of your
mouth, it is possible that you will not be able to tolerate them without
constantly clenching on them causing headaches and constant sore spots.
If, on the other hand, you get new dentures every 5 to 7 years (as we
recommend), your dentist can usually restore the length of your face and the
shape of your mouth because the new dentures will be only a little
"larger" than the old ones.
2.
As the bone that supports the dentures changes shape, more and more space
forms between the base of the denture and the gums that it rests on.
This is why your old denture begins to get looser and looser. If you
simply wear thick denture adhesives, the denture may retain some suction.
In other words, they still have RETENTION, which means that they
resist being dislodged vertically. But
thick layers of denture adhesive do not support the denture well and it moves around when
chewing (and even talking) and dislodges easily. In
other words denture adhesives do not lend the denture STABILITY.
Stability is the denture's ability to resist horizontal dislodgement--side
to side or front to back. Lack of stability leads to sliding of the
denture when biting, chewing or sometimes just talking with consequent
breaking of the suction so that it tends to loose retention and drop out
unexpectedly.
If you wear loose dentures
long enough, even with adhesives, your body will tend slowly to build more and
more
soft flabby gum tissue to fill the spaces between the denture base and
the underlying bone. Eventually, you might even get to the point where
the space between the bone and the denture is completely filled with this
flabby tissue, and you no longer need adhesives to retain the denture.
This may seem like a good thing, but the denture moves around on all that
flabby tissue like it was sitting on Jello. Jello WILL stick to the wall
(it has retention), but it will not support any weight (it lacks stability).
Even if a dentist makes you a
new denture, the flabby tissue that now covers the bone will cause the new
denture to lack stability as well, and you may be disappointed in the result,
with a new denture that dislodges as easily as the old one. If this has
become a major problem, the soft tissue can be surgically removed and
the ridge of bone surgically altered to create better supporting
structures. This is frequently money very well spent, so if your dentist
recommends it, give it careful consideration.
On the other hand, you can avoid the problem of flabby
tissue altogether by having your dentures
relined every two
years. This procedure keeps the denture well adapted to the bony ridge
and does not give the body enough time to build the redundant tissue in the
spaces between the bone and the denture base.
3. If you have been wearing the same denture for a long time (over 7
years) without routine maintenance, you cannot always expect the dentist to
restore your original smile. The reason for this is that during the
time you have been wearing the denture, your body has been adjusting to the
slow changes that both the denture and your mouth have been undergoing over
the years. The ridges (gums) have shrunk back, the denture has worn,
and the way you bite has changed, sometimes drastically. As the
dentures slowly retreat behind your lips, you are forced to stick out your
lower jaw more and more over the years to allow the back teeth to make
contact. During this period, the muscles that work the jaws tend to
change permanently to accommodate the new way of biting that the old denture
has forced upon the jaws. A change in muscle length and bulk may make
it impossible for a dentist to fabricate new dentures with the wider smile
or longer teeth you had hoped to get from a new denture.
| I learned this lesson the "hard
way". To read an account of the lesson itself, click
here to learn the story of my patient
Popeye. |
4.
Lower dentures can be very hard to wear. Many people with upper
and lower dentures often wear only the upper on a routine basis, since
uppers are retained with at least a degree of suction. Lower
dentures are the real challenge, since they are retained mostly by the
muscles of the lips and cheeks, and the tongue. Fortunately, now
there is a new, relatively inexpensive way to stabilize the lower
denture. Indeed, this technology can make the denture act almost
like real teeth.
The image to the right is a schematic of a lower denture
retained in position by four mini implants. Mini implants, unlike
standard implants can be placed in the jawbone in a one hour procedure
that often does not involve cutting an incision in the gums.
The denture (usually an old denture) is then retrofitted with tiny
housings that contain a rubber o-ring made to slip over the implants.
The denture then snaps into position over the implants and the patient
can wear, and use the denture immediately upon walking out of the
office. The cost of this procedure is much less than the cost of
retrofitting a denture with standard implants, and since the surgery is
much less invasive, it can be performed on nearly any patient with
nearly any medical condition. Click on the image to read more.
5. Plastic teeth Vs Porcelain teeth
Denture teeth may be made out of either plastic or porcelain,
however dentists always prefer to order plastic. Patients frequently
want to know why, since porcelain teeth are not prone to wear and thus
should last longer. The answers are as follows:
-
While the porcelain teeth do not wear, the plastic base
into which they are set does. Porcelain teeth do not bond
chemically with the denture base, and they are held onto the plastic
base using a diatoric method, ie using either a hole in the tooth into
which the plastic flows during processing, or wires fused into the
porcelain, both of which mechanically hold the denture tooth on the
base. Over time, porcelain teeth start to pop off the denture
base. In addition, the base retains water and odors and gets
weaker over time.
-
As discussed above, the structure of the oral tissue
under the denture changes over time. When a patient removes his
old denture and observes that the teeth still look good, they tend to
avoid getting a new denture when the old one becomes dangerously
unserviceable. They do not realize that the resorption of their
ridge has caused the denture to disappear under their lip, or that their
gums have become flabby. As long as the front teeth remain in
place, they do not even mind the loss of a few back denture teeth.
They don't even realize that they are holding the denture with their
tongue rather than with the suction characteristic of a newer denture.
Porcelain denture teeth are a bit like chrome hubcaps on an old rusted
out jalopy. In the end, it is better to have the teeth wear at the
same rate as the rest of the denture in order to remind the patient that
it is time to get a new one.
-
Porcelain denture teeth will seriously wear natural
teeth.
In the image above, the top teeth are what is left of an
old (35 years) denture with porcelain teeth. The patient kept it
for years because at least the four front teeth stayed in place, and he
could keep it in his mouth provided he never took it out. The
lower teeth, or at least what is left of them, are natural. This
is what years of chewing and grinding with a porcelain denture can do.
Plastic denture teeth would have worn at the expense of the natural
ones, and would have preserved the natural lowers.
-
We always recommend new dentures every five to seven
years. If a patient keeps to this schedule, plastic teeth do not
wear significantly enough to be a cosmetic issue, and any remaining
natural dentition remains pristine. This schedule also keeps the
facial appearance intact.
The
different types of dentures and the steps in making them
What
is a reline?
You
can find much more about the process of resorbtion and how it
can be prevented by visiting an entire page devoted to
it: 
