We understand that many people are cynical when we say that dental implants last a lifetime. After all, most of us have had a negative experience with a “lifetime” warranty that really only lasts five years or less.
But dental implants aren’t most products: their lifetime, as defined by traditional product failure analysis, really is longer than anyone has been able to figure out. For most intents and purposes, it’s infinite.
The “Bathtub Curve” of Product Lifetime
Every product has what is known as a “bathtub curve” that describes its failure rate. When products first enter service, their failure rate is relatively high. Use exposes inherent flaws in the material, problems of compatibility, inappropriate usage, or difficulties with related equipment.
After a short period of time, the failure rate slows down, and there’s a small number of random failures over the course of what is known as the product’s useful lifetime. Then, at some point, a product reaches the end of its useful life and failure rates increase again, and, eventually, we reach a point where the probability of failure is basically 100%.
A product’s “lifetime” is defined as the point at which we expect some percentage (typically 50%) of the product to fail.
Applying the Bathtub Curve to Dental Implants
Now, let’s look at how this bathtub curve applies to dental implants, using this large, 20-year study of dental implants.
In this study, we can see there’s at least one side of the bathtub: an initially high failure rate. Of course, this is relative. There were nearly 200 implant failures (out of a total of more than 12,500 implants) during the first year. This accounted for about 60% of the total failures. (Most of the time, failure is due to gum disease or failure of the implant to integrate into the bone.) Over the next 16 years, another 119 dental implants failed, which accounts for a total failure rate of only 2.5%, though because of the way statistical analysis is done, the survival rate was only reported as 93.3%.
But we never see the other side of the bathtub. We don’t know the point at which dental implants will inevitably begin to fail, if there is such a point. We only know it’s more than 20 years away. Other 20-year studies come to similar conclusions. And it’s not known if we’ll ever figure out where the other side of the bathtub is: people who have had dental implants for more than 20 years are likely in their 80s or 90s, and many of them pass away with their dental implants in place.
So, when we tell you that dental implants last a lifetime, we really do mean it.