Missing Tooth and Tooth Replacement options for Long Island, Suffolk County and Babylon, New York (NY)

Options for Replacing a Missing Tooth

When tooth is lost the individual faces many choices. The first choice is should I replace the missing tooth? The second is what is the best way to replace it? In making these decisions there are many factors to consider and research data to be evaluated.

There are three basic ways to replace missing teeth.

These include:

1) Removable partial dentures
2) Tooth supported bridges and
3) Implant supported teeth.

Removable partial dentures have metal clasps that clip onto teeth to hold the device in the mouth. Patients need to take these in and out for cleaning after eating.

Tooth supported bridges rely on the adjacent teeth for support. The teeth next to the missing tooth space are ground down and the bridge is cemented onto them. This bridge does not come in and out and relies on the integrity of the adjacent teeth for support.

Dental implants. The final method of tooth replacement is the dental implant, which is a replacement for the root of a tooth. The implant is placed where the root of the missing tooth used to be. The replacement root is then used to attach a replacement tooth.

Should I Replace a Missing Tooth?

There are a number of studies reporting on survival of teeth next to missing tooth spaces. These studies look at the survival of the teeth next to the missing tooth space in cases where the missing tooth is replaced and the missing tooth is not replaced. Studies show that there is a significant loss of adjacent teeth if the missing tooth is not replaced. Tooth replacements with fixed bridges attached to teeth improves the survival of the teeth compared to no replacement.

When removable partial dentures are used to replace missing teeth, the failure of the adjacent teeth is much higher than if there was no replacement, or if the replacement was with a tooth supported bridge. Patients who do not replace missing teeth may experience shifting of teeth, spaces opening between teeth (resulting in food impaction), collapse of the bite, alterations in their chewing ability, TMJ pain, and trauma to the remaining teeth. People sometimes don’t replace teeth that are “in the back” of the mouth because no one sees them. The back teeth are needed to support the bite and grind up food. We can all swallow food that is not chewed thoroughly, but this compromises the nutrition we extract from our diet. When enough back teeth are lost the front teeth can start to flare or become “buck teeth” as they carry forces in excess of what they were designed for.

Let’s look at some of the data from scientific studies that look at replacing missing teeth.

VA Medical Center Longitudinal Study Shugars JADA 1998

19% of adjacent teeth failed if the space was untreated
10% failed if the space was treated with a tooth supported bridge
30% failed if the space was treated with a removable partial denture

Permanente Dental Associates looked at 317 patients who wore tooth supported fixed bridges for an average of 6.7 years and removable partial dentures for an average of 4.2 years. Their findings:

13% of adjacent teeth failed if the space was untreated
7% failed if treated with a tooth supported bridge
17% failed if treated with a removable partial denture

Truman Medical Center, 8.6 years tooth supported bridge and 7 years observation for removable partial dentures

12% of adjacent teeth failed if untreated
7% failed if treated with a tooth supported bridge
22% failed if treated with a removable partial denture

In conclusion, we can see the following:

• There is significant loss of adjacent teeth (ranging from 12%-19%) if the missing tooth is not replaced.
• Tooth supported bridges improve the survival rate, with abutment tooth loss from 7%-10% at 6.7 and 8.6 years.
• Removable partial dentures increase abutment tooth failure rate ranging from 17% to 30% at 4.2 to 7 years.
• There is no significant difference in the statistics of the various studies.

We said earlier that there are three basic ways to replace missing teeth. They are removable partial dentures, tooth supported bridges and implant supported teeth. Lets looks at each of these options.

Tooth Replacement with Removable Partial Dentures

Removable partial dentures (also called partials) have clasps that attach to the teeth. The teeth that hold the partial are called “abutment teeth”. Sometimes crowns with hidden interlocks are used to attach the partial denture so that the metal clasps do not show.

Numerous studies have demonstrated the problems clinicians and patients see with removable partial dentures. Koivumaa showed that only 80% of people still wore their partial dentures after the first year. Carlsson showed that only 60% wore them after 4 years.

Why did patients pay good money for these partials and stop wearing them? Discomfort. Wetherell showed that the teeth that bear the twisting forces of the partial denture clamps fail at an alarming rate. For patients who were able to tolerate and wear their removable partial dentures, his data showed 40% survival at 5 years and 20% at 10 years. What this means is that as a partial denture is worn longer and longer, it is more destructive to the supporting teeth. As these teeth fail, new partials are made which then begin destroying new abutments teeth. In some cases, a removable partial denture is a stepping stone to a full denture.

Tooth Replacement with Tooth Supported Bridges

The next method of tooth replacement is a tooth supported bridge. In this method, the teeth adjacent to the missing tooth are ground down and a bridge is placed. This bridge may be 3 or more teeth. The two caps on the teeth are called abutments and the cap connected to the abutment teeth is called the pontic. Although bridgework has served patients well for decades and is usually preferable to a removable partial denture, they have their limitations including potential failure of the abutment teeth.

A natural tooth has two parts, the crown of the tooth is the part you see, and the root of the tooth is the part that is in the bone. A tooth supported bridge only replaces the crown and not the root of the root. As a result, the bone where the root used to be will start to atrophy or wither away. When you lose a tooth you lose part of your jaw bone as well.

Although the studies report various success/failure rates for tooth supported fixed bridges over different time spans, many studies appear to report similar results for periods of 10-15 years.

Various studies report the mean life span to be about 10 years, with decay and root canal problems the main causes of failure. Studies also report that a significantly higher percentage of abutment teeth (the teeth that are ground down to support the missing tooth) require root canal therapy compared to nonabutment teeth.

Often the failure of tooth supported fixed bridges result in loss of abutment teeth and the need for additional abutment teeth and pontics in the replacement prosthesis.

Failure of tooth supported bridges falls into two categories, biologic and mechanical:

Biologic Failures:
*Caries-(tooth decay)
*Periodontal disease (gum disease)
*Endodontic or periapical problems (root canal problems)

Mechanical Failures:
*Loss of retention (the bridge comes uncemented)
*Fracture of porcelain
*Wear of gold restoration
*Fracture of bridge
*Fracture of solder joints in the bridge
*Fracture of abutment tooth or root
*Poor foot of the bridge
*Poor contours
*Poor aesthetics

Let’s look at the studies concerning survival of tooth supported bridges:

• Palmquist 1993 103 fixed bridges 18-23 years observation only 79% success
• Lindquist 1998 140 bridges 20 years, only 65% success
• Yi 1995 10-15 years only 70% success (8% of abutments had to be extracted)
• Glantz 1993 15 years only 64% success
• Hammerle 2000 5-26 years 115 bridges and 229 abutment teeth
• 12% of abutment teeth died and needed a root canal
• 8% of abutment teeth got cavities
• 8% of the bridges came uncemented
• 3% of the abutment fractures
• Scurria 1998 combined data from 9 studies giving a total of 2761 abutment teeth observed over 3-20.5 years. The 10 year success was 85%, 15 year success 66%.

In conclusion, there seems to be agreement in the studies that:

• Tooth supported bridges are about 66% successful for periods of 15 years.
• The mean life of a tooth supported bridge is about 10 years.
• Studies report abutment tooth loss ranging from 2% to 30% for periods of 8-14 years.
  

Replacing Teeth with Dental Implants

The final method of tooth replacement to be considered is the dental implant. An implant is a titanium replacement for the root of a tooth. The implant fuses with the bone. A crown is then attached to the implant. The implant crown does not depend on the adjacent teeth for support or longevity. The implant crown does not invade or damage the adjacent teeth. Another major advantage of the implant is that it stimulates the bone much like a natural root does. By replacing both the root and the crown of the missing tooth we do not see the loss of that segment of the jaw bone like we do with a tooth supported restoration.

In contrast with the success rate of the tooth supported fixed bridges over extended periods of time, implant supported teeth have a much higher survival rate and have become very predictable. Immediate success rates are 98%+ and once the implants achieve osseointegration (fusion with the bone) the failure rate is extremely low. As opposed to failure of tooth supported fixed bridges, implant failure does not compromise the adjacent teeth and increase the risk of their loss.

The two most significant advantages of implant replacement teeth over tooth supported fixed bridges are that healthy adjacent teeth do not need to be ground down and the bone in the missing tooth site is preserved. Other advantages include: decreased risk of decay and root canal treatment on abutment teeth, improved ability to clean the front and back surfaces of adjacent teeth (with single tooth replacement), decreased risk of cold or contact sensitivity of abutment teeth and decreased risk of abutment tooth loss.

These advantages are so significant to the health of the adjacent teeth and maintenance of the arch form that implant prostheses have become the treatment of choice in most situations.

Since the late 1950’s the use of dental implants has developed into a routine method for treatment of the jaw with no teeth at all. Numerous studies have been published going back to the 1970’s indicating success rates in these cases of over 98%. Although long-term documentation is still not as extensive as for the jaw with no teeth, the results for single tooth replacement are excellent. The following is just a sample of the results for single tooth replacement.

• Priest 1999 99 patients, 116 implants 10 year survival 97.4%. Dr. Priest commented that “The use of implants to support dental prosthesis (replacement teeth) demonstrated a tooth preserving effect by avoiding the use of intact teeth as abutments.”
• Engquist 1995 58 patients, 82 implants, 97.6% survival at 5 years
• Krenmair 2002 112 patients, 146 implants 7 years 97.3% survival
• Gomes 1997 376 patients 696 implants 5 years 96% survival
• Lindhe 1998 Combined the data of 19 studies for a total of 2686 implants, 570 single crowns and 2116 in implant bridges, 6-7 year survival of 93.6% for implant bridges and 97.5% for single implant crowns.

If we compare the data on survival of implant supported restorations versus tooth supported restorations we can see that the success rate for implant supported restorations is significantly higher.

Retreating a Root Canal Tooth or Extracting it and Placing an Implant.

Sometimes a tooth that has a root canal becomes re-infected or never became healthy after root canal therapy. The patient and clinician must then decide whether to retreat the root canal, or replace the tooth with an implant. Success rates for root canal therapy are as low as 53% and as high as 95% according to Eriksen 1991. A root canal infected with bacteria will develop a hollow space in the bone at the tip of the root. If this occurs, the success rate for the root canal retreatment is reduced 10-20% according to Sjorgren 1997.

Cycle of Re-Restoration

Adult patients often have one or more crowns as a consequence of large restorations that had been broken down and needed to be replaced in order to restore the integrity of the teeth. Tooth decay and root canal therapy are the primary causes for failure of crowns and these teeth are at increased risk for extraction as a result of these complications, which are a leading cause of loss of back teeth.

It is interesting to note that as a result of decay or root canal failure, nearly 30% of the people between the ages of 50 and 59 years examined in a US National Survey had one or multiple missing back teeth.

Brantley published this data in 1995:

• The more frequently a patient visited a dentist, the more restorations he was likely to receive. Furthermore the more restorations a patient had, the more he was likely to receive in the future.
• 70% of dental treatment recommendations result in an increased number of restored surfaces.
• Prosthesis failure is common (due to failure of a tooth under the prosthesis).
• Replacement restorations are larger than the ones that preceded them.

What this data shows us is that crowns and fillings have a limited life span and when they need to be replaced the next restoration is usually larger or more complex than the previous one. We call this the cycle of re-restoration. As we saw in the data above, the mean life span for a tooth supported bridge is 10 years. Think of how many cycles of re-restoration will be necessary (and the huge cost and time commitment) with a tooth supported tooth replacement verses an implant supported tooth replacement.

Success Summary:

In conclusion it is important to thoroughly evaluate the treatment options for tooth replacement and root canal treated teeth, taking into consideration the prognosis for long-term success.

Tooth Supported bridges

85% successful at 10 years
66% successful at 15 years

Implants

90% to 98% successful for periods of 5 to 30+ years

Root canal retreatment

53% to 95% successful
10% to 20% reduction in success with bone loss at tip of root

Dental implants are highly predictable both short term and long term and are more permanent than conventional options. They protect both the dentition and the bone, and decrease the need for future dentistry.

The 1990’s were a decade during which dental implants moved from the fringes of dental treatment into the mainstream of therapy. Today, there is substance to the claim that implants are the standard of care and the optimal solution for replacement of missing or failing natural teeth. The scientific literature supports this paradigm shift in dentistry. Of course every patient is different and each instance of tooth replacement must be evaluated on its own merits with the patient and their dentist. We hope that this material has provided some insight into the clinically documented data regarding the various tooth replacement methods. You only get one body and the choices you make are important.