In general, root canal therapy is a good option to consider if you have an infected tooth. In many cases, it’s preferable to extraction and replacement of the tooth. However, we have to be careful to take all factors into account to be sure we’re doing the procedure with the highest rate of success. Overall, root canal therapy is a highly successful restorative dentistry procedure, but it can be sensitive to technique.
Now a new study published in the Journal of the American Dental Association (JADA) reminds us that tooth position can be a major influence on the potential success of root canal therapy.
A Small, but Long-Term Study
Root canal therapy is a very successful procedure, which can make it hard to identify factors that lead to failure. In order to get a good set of failure data, long-term follow-up is necessary. This study has a 22-year follow-up for a series of 88 restorations. This is not a huge number of restorations, but the length of the study makes up somewhat for the small sample size.
This study was performed in Spain. The procedure used in this study is less common in the US these days, and involved the use of metal amalgam fillings around a titanium post. The teeth were then topped with a porcelain-fused to metal (PFM) crown.
Most (58) of the root canals were performed on maxillary teeth. The root canals included six incisors, 18 canines, 28 premolars, and 36 molars.
At the five-year follow-up, the survival rate was well over 90%, but by the 18-year follow-up the survival rate had dropped significantly to only 65%. By the end of the study, it had fallen further, to just 52%.
When researchers looked at the relationship between the position of teeth and their success rates, they found that anterior teeth were 3.26 times more likely to fail after root canal treatment than molars.
Since 2005, there have been four studies on this question. Three of them agree that tooth position affects the survival of endodontically treated teeth. This means that if we are considering root canal treatment or dental implants for an anterior tooth, we may be more likely to recommend dental implants.
Not as Good as Dental Implants
What is striking about this study is the overall poor success rate of teeth treated with root canal therapy. Sometimes, endodontic treatment is said to be as good as or better than dental implants. But this study certainly cast doubt on that assessment.
The largest long-term study of dental implant survival showed that 93% of dental implants are still in place at 17 years.
Of course, the low survival rate in this study may be related to the particular approach used for root canal therapy. Nonetheless, it is certainly an eye-opener.