There are 4 different types of
full dentures. They are "standard dentures", "immediate
dentures", "implant retained dentures", and "Cu-Sil
dentures".
The
standard denture
As you can see from the
picture below, the back of a standard denture ends just behind the hard bone in
the roof of the mouth. They do this because they require as much surface
area as possible to maximize retention and stability. In the case of people who
gag, the back of the denture can be cut forward making the denture base look
more and more like an arch. However, the more it is cut back, the less
stable and retentive it will be!
Standard dentures are made for
people who are already missing all their teeth. The top denture relies on
"suction" to retain it, and the hardness of the underlying tissues
for its stability. It generally takes 4 or sometimes more appointments to
make a set of standard dentures.
The first appointment consists of an oral examination, sometimes
X-Rays, and a set of impressions of the upper and lower edentulous (toothless)
ridges (gums). These impressions are poured with plaster to form accurate
models of the shape of the edentulous ridges. Other parameters are
determined such as the shade, size and shape of the teeth that will be placed
on the new dentures.
Upon occasion, the dentist
will recommend surgical alteration of the ridges to remove flabby tissue which
will interfere with the stability of the denture, and sometimes to alter the
shape of the underlying bone allowing for a better fit. In most cases,
such surgery is not essential, but can create the conditions for a MUCH more
satisfactory final denture. Alterations like this are generally money
well spent!
In some cases where a patient
has a differently shaped ridge, the first set of impressions are used to make
custom fitting impression trays for a second, more accurate impression.
In this case, there will be one extra appointment in addition to the standard 4
mentioned above.
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Both upper
and lower wax rims are adjusted to fit correctly in the patient's mouth so he
can speak correctly without the wax rims "clicking" together, and
so that the upper and lower rims fit together evenly. Ideally, the wax
rim should be visible slightly below the patient's lip when the lip is at
rest. When the patient smiles, the position of the lip is marked in the
wax to help the lab decide which set of teeth are appropriate for this
patient. Once these relationships are correct, the rims are sent
to the lab where they are used to fabricate the wax-try-in. |
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This gives
us the opportunity to see how the denture looks and works before we are
committed to the setup. At this point, if something is wrong, it can be
changed. If the teeth look too long, or the patient clicks when
talking, or the midline is wrong, we can send the denture back to the lab
where a technician can melt the wax and reset the teeth to
specification. Here, the patient is smiling, and the upper lip falls at
the top of the teeth, which is the ideal result. |
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We try the denture in as many
times as necessary until the teeth look and function like we want them to. What
you see is what you get! When everything is perfect, the denture is sent
back to the lab to be processed and finished. The old lose fitting base
and all the wax are discarded, and replaced by a tightly fitting plastic
denture base.
The fourth appointment is the
insertion date when the patient walks out of the office with new
dentures. The plastic tends to shrink while being processed, so some
adjustment is usually necessary before they will get the suction that you might
associate with a new denture. How stable the denture is depends upon the condition of the
ridges.
Immediate dentures (sometimes called temporary
dentures) are actually made BEFORE the natural teeth are extracted.
The patient walks into the office with natural teeth, and walks out with false
teeth. The teeth are extracted, and a prefabricated denture is inserted
directly over the bleeding sockets. The patient is still numb from the
extractions, and nothing hurts until he gets home. Generally, most
patients do not complain of much pain after their teeth are extracted and the
immediate denture is inserted. The denture acts like a band aid and
reduces pain.
The construction of an
immediate denture requires only one or two preliminary appointments before the
insertion date, depending on how many natural teeth the patient has left.
They usually work out reasonably well. When the patient leaves, he looks
much better than when he walked into the office. The bone that supported
the original teeth is still intact, and the gum tissue is firm. For the
first week or so, the denture remains stable and reasonably retained.
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But there are a number of
problems associated with immediate dentures. These problems account for
the alternate name; "temporary dentures":
1. If the patient has more than
one or two remaining front top teeth, it is usually impossible to do a wax
try in. The denture teeth are placed in about the same position as
the natural teeth before extraction. Even though the denture teeth will
be straight, and clean, their position may not be ideal because there is no way
to preview them as we do with a standard denture. For this reason, not
everyone will be happy with the final appearance of their immediate denture,
and may wish to invest in a new one at the end of about a year when most of the
healing has taken place.
2. After the natural teeth are
extracted and the immediate denture is inserted, there is a relatively fast
loss of the bone that used to hold the natural teeth in place. By the end
of three weeks, enough bone has been lost that there is a LOT of space between
parts of the denture and the healing gums. This leads to rapidly
increasing looseness and sore spots which must be removed frequently. In
some offices, the dentist will include a free temporary "soft" reline
at about one month after the extraction/insertion date. This is a simple
way to tighten the denture against the gums, and since the material is a bit
rubbery, and frequently medicated, it makes the denture much more comfortable
until enough healing has taken place to do a permanent "hard" reline
(at additional charge).
3. At the end of 4 to 6
months, the immediate denture must be relined with the same acrylic that the
denture base was made from originally. The longer you wait, (no more than
6 months), the longer you can expect the denture to remain tight before another
reline is needed. The hard reline is a separate procedure and the cost is
NOT generally included in the original price of the immediate denture.
Thus the immediate denture ends up costing a bit more than the standard denture
when the cost of the reline is taken into account. The hard reline marks the
official transition of the immediate denture into a standard denture.
There are a number of drawbacks associated with full dentures, and not
everyone can successfully wear them. In many instances, false teeth are
not especially useful because of retention or stability problems. For
this reason, even a single healthy tooth left in place can stabilize an
otherwise unstable full denture.
Only recently has it become
possible to build a denture leaving a hole here and there to allow a few
remaining teeth to poke through without ruining the suction which generally
holds the denture in the mouth. The Cu-Sil denture has holes for natural
teeth. These holes are surrounded by a gasket of stable silicone rubber
which hugs the natural teeth and allows the rest of the denture to rest against
the gums giving the benefit of suction in addition to the mechanical stability
offered by the immobility of the natural teeth. These are especially
useful in situations in which the remaining teeth are on the same side or area
of the arch as in the example below. Even a single remaining tooth in the
arch can increase the stability of the entire denture several hundred percent
over a completely edentulous (no teeth) arch.
CuSil dentures are not the
best solution for people with numerous, evenly distributed, stable natural
teeth. They are advertised mostly as "transitional" dentures
meaning that they are especially recommended when the remaining teeth are likely
to be lost (eventually) for any reason, or in cases where stable teeth are
poorly distributed about the dental arch (as in the case below). A CuSil
denture can stabilize loose teeth and, with care, can extend their lives.
It is also easy to replace lost natural teeth on the CuSil denture, and the
denture can be relined like any other standard denture. In other words,
the CuSil denture can eventually be transformed into a regular full denture if
the patient loses all the natural teeth. I have found them to be
especially useful for upper dentures, but more of a problem for lowers.
Lower CuSil dentures are prone to breakage if the patient is a heavy bruxer
(grinder), especially if the remaining natural teeth are located in the front
of the arch. This is because the holes that allow the penetration of the
natural teeth weaken the architecture of a lower denture.
If there are many stable
natural teeth remaining, and they are distributed on both sides of the arch
(unlike the example below) with some in front and some in back to lend support,
a partial
denture may be as good or even better solution. Partial dentures have
the added advantage of not having to cover the entire roof of the mouth.
Note: If you wish to find a
dentist who will make you a Cu-Sil denture, you may be able to get a referral
from one of the 125 dental laboratories throughout the US and Canada who make
them. In order to find a dental lab who has experience with this product,
you may try to contact the manufacturer of the resins (Present Investment) at
the following telephone number: (954) 426-4666. This manufacturer is
located in Deerfield Beach Florida and is open 9-4 Monday thru Friday.
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The images above show a Cu-Sil
denture which was used as an immediate denture. The patient's two front
central teeth were extracted, leaving the natural canine and molar on the
patient's left side in position. The image on the lower right shows the
case immediately after the two central teeth were extracted and the denture
inserted. The black arrow points to one of the patient's two remaining
natural teeth. Cases like this tend to result in an extremely
stable and retentive denture.
Overdentures are defined as
any removable tooth replacement device that is inserted over existing teeth or
their remnants, replacing these teeth with false teeth. Prior to modern
dentistry, overdentures were very nearly the universal tooth replacement device
since surgical removal of teeth was painful, dangerous, and frequently
impossible without modern anesthetics. In those days, dentures were made
to fit over the rotting stumps of decayed or broken teeth.
Today, non restorable teeth
are generally removed prior to the placement of a removable prosthesis,
however, there are still instances where these teeth can be maintained to the
patient's advantage. The most frequently seen overdenture today involves
teeth that have had root canal therapy. If the roots of these teeth are
still serviceable, the crown may be cut off at gum line and a removable
appliance may be placed over the stumps. Sometimes, the stumps are
themselves covered with filling material or cast metal copings in order to
protect them from decay. The advantage to this is that the roots of these
teeth can maintain the bone that supports them. This bone would otherwise
resorb away leaving less tissue to support the denture. In addition, the
root itself can serve as a "rest", or a vertical support for the
denture allowing for more stability than would otherwise be available.
The addition of a soft denture
material such as CuSil on
the denture surface that immediately overlies the rigid root stumps allows the
overdenture to nestle more snugly into the soft tissue on the roof of the
mouth. This allows for more suction to develop and can frequently improve
the retention of an overdenture.
Implants,
as mentioned elsewhere, are quite expensive (generally about $2000 apiece, not
counting the tooth replacement that goes on top of them), but quite effective
in retaining an otherwise non retentive denture. A titanium
"screw" is actually placed into a hole drilled into the bone to
approximate the position of teeth. After several months, the titanium has
integrated (attached) into the bone, and the implant is then uncovered and a
post which "pokes" through the gums into the mouth is attached to the
implant. This post may support a porcelain tooth, or it may support an
attachment for a denture. If the patient has NO teeth at all in any given
arch (upper or lower), a full mouth of individual implants attached to
porcelain teeth and bridges could cost about what an expensive automobile
costs.
On the other hand, a minimum
of 2 implants can maintain a lower denture which would not otherwise be
tolerated by that patient. More than two implants are needed for upper
implant retained dentures. Although the dentures that fit over implants
are considerably more expensive than standard dentures, they offer the added advantage
of allowing upper dentures to be built in the shape of an arch instead of
having to cover the entire palate. This is of special significance to people
who otherwise cannot wear full dentures because they make them gag.
Implant retained dentures have
special significance for people who cannot wear lower dentures. As an
edentulous (toothless) person ages, and the bone continues to resorb away,
lower ridges frequently disappear entirely. Thus there is no vertical
bone underlying the gums to stabilize a lower denture. These people
frequently cannot wear a lower denture at all. The addition of two
implants in the front of the lower jaw can make it possible to retain a lower
denture which would otherwise be impossible for the patient to tolerate. The image
on the left below shows a pair of ball attachments on implants, and the denture
that fits over them is shown in the image on the right.
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Mini implant retained dentures
Since their introduction in the late
1990's, mini implants are beginning to become the standard of care for
retaining lower dentures. Unlike the standard implants discussed above,
there is no three to six month waiting period before mini implants can be
loaded (support the denture). Mini implants can generally be placed
in the lower jaw without cutting an incision in the gums. The only
anesthesia used is an injection directly over the site of each implant.
The old lower denture can then be retrofitted directly over the newly placed
implants, and the patient can use the denture immediately. Furthermore,
because the implants are about the size of a standard wooden toothpick (they
are made out of a titanium alloy), patients who have been told that there is
not enough bone to accommodate standard implants can generally be fitted
with minis. The entire procedure (placing the implants and retrofitting
the old denture so that it is supported by the newly placed minis) takes about
one hour. It is generally painless, and produces very minimal post operative
discomfort. Finally, due to the ease of insertion, this procedure is much
less expensive than standard implants for retaining lower dentures. Click
on the image to read more.
Duplicate
dentures
When a new full denture is
first made, it is possible to make a duplicate, or an exact copy of the denture
cheaply and quickly. This is a "quick and dirty" method of
obtaining a second denture for emergencies. Duplicate dentures are made
by flowing liquid "agar" around the finished denture and allowing it
to harden. (Agar is a gelatin-like material made from seaweed which is
liquid when hot, but cools to form a flexible rubbery substance similar to very
dense Knox Jell-O. When agar is used in dentistry, it is generally called
"reversible hydrocolloid". It is one of the oldest, but still
one of the most accurate impression materials known.) The original
denture is removed from the agar mold (the agar is cast around the denture in
two halves) leaving a hole in the agar where the denture used to be. The
hole is then filled with liquid plastic; white plastic in the tooth indents and
pink to form the base and flanges. The two halves of the agar form are
placed back together and the liquid plastic is allowed to harden.
Duplicate dentures are not especially high quality since the flowable plastic
used to make them tends to be porous and less resistant to wear, and the
delineation between the tooth colored plastic in the tooth indents and the pink
base plastic may not always be exactly at the margins of the teeth, but these
dentures make it possible to keep a spare set of dentures tucked away just in
case the regular denture must be sent out for repair, or is lost and a new
denture must be made. They are frequently delivered to the patient
without adjusting them for sore spots or any other technical modifications to
make them more affordable. Duplicate dentures are only an adjunctive
service and are not intended to take the place of the real thing.
Adjustments cost money, and if the dentist were to spend as much time and effort
on them as he did on the primary service, the duplicate could end up costing as
much as the primary dull denture.