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Dentures (False Teeth)

 

 

 

 Denture  Denture

If you still have teeth, even badly decayed ones, you need to read the page "Should I have my teeth pulled and get full dentures?". It is VERY important to your own future happiness that you fully understand the implications of the decision you are about to make.

Click here to read an exchange of e-mails between me and a patient who  got a denture and found she could not wear it.  These situations happen all the time and can be downright tragic.

Dentures: What you need to understand about your dentures

A new denture will not last you forever, and if your old ones are much over 7 years old, your mouth and face will have changed in ways which will make it difficult, or sometimes even impossible for your dentist to build you satisfactory new ones!  The following discussion focuses on the unfortunate effects of keeping an old denture for too long.

Does your upper denture make you Gag? 
If you have tried everything else, click here.

1. Your mouth and face change in response to wearing a denture

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".  

Edentulous skullYou can find much more about the process of resorption and how it can be prevented by visiting an entire page devoted to it:
Bone resorption and Bone grafting

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. Retention vs. Stability

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 Jell-O.  Jell-O 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. Permanent changes to facial muscles

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.

New hope for people who can't wear their lower dentures

Lower dentures can be very hard to wear.  Mini ImplantsMany 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.

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, i.e. 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. 

Serious attrition

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. 

Gagging

Some people cannot wear their upper denture because they gag.  Unfortunately, there is no pharmaceutical (drugs) way to stop gagging so that you can wear the denture.  There are, however two ways that chronic gaggers MAY be able to tolerate their upper dentures. 

There is no law that says that the center of the posterior flange of the denture (the curving part at the back of the denture where it "stops") cannot be reduced in length.  It is the center of the flange that stimulates gagging, and if this is cut back smoothly, you may be able to wear the denture.  Unfortunately, the more you cut it back, the less suction you can expect from the denture, the main reason the dentist puts the flange back there in the first place.  It is in the posterior palate where the denture finds enough soft tissue to allow the post dam to compress the tissue so that the denture can form a seal.  The post dam is a low hump of plastic over the area of the posterior flange which helps with suction.  As you move the flange forward onto the hard palate, the less compressible the tissue is, and the more likely you will need denture adhesive to keep it in.  You can overcome this to a certain extent if you have the dentist do the cutting back, and then ask him or her to send the denture back to the lab to place another post dam on it.

Or You can get two or more implants in order to hold the denture in place, and then have the entire palatal extent of the plastic removed.

Note to dentists and dental students: The broad butterfly shaped post dam works quite well because it broadens out to take advantage of the softer tissues on either side of the midline, while becoming more narrow and dipping toward the distal as it approaches the midline where the depth of the soft tissue decreases.  (See image below.)  The posterior line of the post dam remains just distal to the hard palate.  There is nothing holy about the posterior extent of the denture if the patient can't wear it because it makes him gag.  You can still get a post dam by taking advantage of the soft tissue on either side of the midline, even with a short palatal flange.  Just Check the softness of the tissues along the new posterior limit and draw the post dam on the denture with a pencil, broadest in the softest tissue and narrowest in the midline, and return it to the lab for processing.

 

Denture flange Where to cut back flange

Posterior flange

Area to cut back

Post Dam

Old Tyme Denture

If all else fails!
Porcelain teeth with soft silver base, retained by springs
c. 1850

The different types of full dentures

Denture relines

Should you have all your teeth pulled and get false teeth?

 

 

 

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