The Longevity of Teeth and Oral Implants

A recent systematic review published in the Journal of the American Dental Association by Levin and Halperin-Sternfeld regarding the longevity of teeth and dental implants has raised some interesting, and long overdue questions. This review should have clinicians talking and hopefully talking among dental specialties.

Levin and Halperin-Sternfeld state that the increasing popularity of dental implants may "result in the extraction of teeth that are salvageable, on the basis of convenience rather than as a result of a comparative analysis of prognosis."

Their systematic review was to evaluate the long term survival rates and treatment outcomes for retained compromised teeth in comparison with long term survival rates for dental implants.  Their research question was: "Is the long term survival rate of dental implants comparable to that of natural teeth that are adequately treated and maintained?"

Their review included studies which evaluated long term (15 yrs or more) effectiveness of implants or long term effectiveness of tooth preservation.  Of the 4943 articles identified, 19 met the inclusion criteria.  Special care was taken to evaluate bias, by using the PRISMA guidelines.  Their discussion points out areas where bias may have affected results in any of the studies included in the review.

Some of the points that I found most interesting in the article include:

Periodontally Maintained Teeth

• Long term tooth survival - Of the several studies which identified the initial periodontal prognosis of teeth, teeth which are periodontally "hopeless" or "questionable" are often most likely to be replaced with implants.  In patients with chronic periodontitis, 20.4% of "questionable" teeth and 34.3% of "hopeless" were lost.  This means that 80% of "questionable" teeth with chronic periodontitis and 66% of "hopeless" teeth with chronic periodontitis, when properly maintained, will survive long term.
• The overall tooth loss rate and tooth loss rate for compromised teeth were not affected by aggressive disease when the teeth were properly treatment and maintained.

Implant Survival

• In the studies involving implants, reseachers rarely reported the cause of implant loss.
• The percentage of implant losses during the follow-up period (minimum 15 yrs) varied between 0 and 33.6%.  The cumulative survival rate ranged between 69.6% and 100%.
• Bone loss data was also available in several studies ranging between 0.05mm and 2.1mm.
• Studies with longer follow up periods (up to 23 years) reported an implant loss rate and a marginal bone loss that were almost twice as large as earlier studies - suggesting that greater bone loss and implant loss occur over longer follow up periods. 
• There was greater variability in the survival of implants placed into grafted sinuses, suggesting the sinus graft may decrease the survival rate of dental implants.
• Since implants are exposed to the same pathogens as teeth, while implants cannot decay, they are susceptible to peri-implantitis.  They concluded that one in five implants will result in peri-implant disease.
• Peri-implant disease currently has no standard treatment.
• Levin and Halperin-Sternfeld concluded "We found that, overall, studies dealing with dental implants tended to present a higher risk of bias. An important issue to consider regarding implant survival is the industry-derived financial support for studies of dental implants. Anecdotal evidence suggests that many of the studies in which investigators report on implant success are supported directly or indirectly by the dental implant industry; however, this information is not always disclosed in the articles. Clinicians should keep this in mind when evaluating these materials."
• There is still a lack of consensus regarding what constitutes a "successful implant"  This criteria varies amount different studies and different implant systems.

Levin and Halperin-Sternfeld also discussed the difficulty of comparing tooth and implant survival. For example, tooth survival studies take an epidemiological approach, while implant studies typically use a distinct or ideal-type of patient.  Dental implant systems are constantly changing and many earlier systems are no longer used.  Researchers have studied the rate of tooth loss for much longer than they have studied the rate of implant loss.  Levin and Halperin-Sternfeld stated, "When assessing the general loss rate of teeth and implants over follow-up periods of at least 15 years, we found a range of 3.6 to 13.4 percent for tooth loss and a range of 0 to 33 percent for implant loss.  This may imply a generally higher rate of implant loss than tooth loss."  A final point of their discussion is that "dental implants are not the reference standard for replacing compromised teeth because they will not survive forever".

Levin and Halperin-Sternfeld made several important points regarding dental implants that are often left out of the treatment planning discussion/informed consent regarding dental implants.  They concluded that, "…the decision to retain properly treated and maintained teeth for as long as possible seems to provide an overall solution that can reduce the treatment risks over the long term".

Further Discussion

A recent survey by Azarpazhooh et. al. demonstrated a declining pattern of preference for root canal therapy (RCT) in favor of implant supported crowns (ISC) among general dentists, periodontists, prosthodontists and oral surgeons as opposed to endodontists.  This declining pattern showed a significantly higher preference for ISC over RCT retreatment.


Implants LOOK and FEEL like natural teeth when
they are next to a natural teeth.

Given the historical success of endodontic therapy, what would cause this trend?

Effective marketing by implant manufacturers has gone a long way to convince the public and some dental practicioners that implants are just like teeth.  Some even promote them as superior, when in reality they are very different and should not be compared as alternative treatments.

We recognize that industry is behind most of the innovation that we see in dentistry today.  However, when these same companies are also the financial backers for the research done to evaluate these products there is a serious conflict of interest.  When universities and clinicians are financially supported by these same companies, they forfeit their impartiality and ability to give an objective opinion.  When implant companies or their clinician representatives are the main source of implant continuing education, we may begin to understand how a preference towards more aggressive implant placement is developing.

As clinicians, we have the responsibility to understand the research, interpret the bias, see through the sales pitch and provide our patients with the best treatment options and maintain our fiduciary/ethical relationship at the same time.  This review by Levin and Halperin-Sternfeld makes a bold statement in support of Holm-Pedersen and colleagues' conclusions "that implant survival will not surpass tooth survival over the long term." This is very different from what we hear from the implant manufacturers and their marketing teams.

To read the abstract or access the full article: click here

I look forward to your comments. This article is meant to begin a discussion.

If you don't want to share them here, then forward this article to a colleague and have a discussion with them.

SOURCES:

1. Levin, L., Halperin-Sternfeld, M. "Tooth Preservation or Implant Placement - A systematic review of long-term tooth and implant survival rates" 2013 JADA 144:10, 1119-1133.

2. Azarpazhooh, A. Dao, T., Figueiredo, R., Krahn, M., Friedman, S.,  "A Survey of Dentist' Preferences for the Treatment of Teeth with Apical Periodontitis" 2013 JOE 39:10, 1226-1233.

3. Holm-Pedersen P., Lang, N.P., Muller, F. "What are the Longevities of Teeth and Oral Implants" 2007 Clin Oral Implants Res 18(suppl 3):15-19.