Survival rate vs. success rate

Studies of crowns, root canals and implants report two different numbers, and they are easy to confuse. A survival rate counts what is still in the mouth. A success rate counts only what is still there and also meets a stricter standard, such as limited bone loss, no mobility, no pain or no complications.

The gap between them can be meaningful. In a review of immediate implants placed in molar sockets that Ryan covers, one-year survival was 96.6% but success, measured against the stricter criteria, was 93.3%. Quoting the survival figure as a "success rate" to a patient overstates the result.

The time frame matters as much as the definition. The often-repeated claim of a 98% improvement from crowning a cracked tooth early turns out to be a one-year survival rate, not an improvement percentage; the same study's eleven-year survival was 55.9%. Before quoting any rate, check which one it is and over how many years.