This month’s Endo Newsletter topic: Effect of Delayed Crown Placement On Retention of Endodontically Treated Teeth

It has been demonstrated repeatedly that the quality of a coronal resto­ration after endodontic therapy is crucial to the long-term success and retention of the tooth. Crowning an endodontically treated tooth with a full coverage crown has also been shown to increase the tooth’s reten­tion. In addition, there is some indica­tion that the timing of placement of the full coverage restoration has also an impact on success rate.

To that point, a recent study found that teeth crowned >4 months after endodontic therapy were 3× more likely to be extracted than were teeth crowned within 4 months. That study, however, was performed in a uni­versity setting with a relatively small sample of <900 teeth, so the question remains whether the same outcomes apply to a private practice setting.

To determine the effect of delayed crowning of endodontically treated teeth in a general setting, Yee et al from Marquette University School of Dentistry, Wisconsin, researched the database of Delta Dental of Wisconsin. They collected data from all insurance claims for endodontic therapy over a 13-year period, includ­ing in their total sample all teeth that had subsequently received core or post/core, and a crown. More than 160,000 teeth fit the inclusion criteria in the database. These teeth were then cross-referenced to see whether they had subsequently needed retreatment, apicoectomy or extraction.

The authors found that timing of post/core placement after endodontic treatment varied quite a bit. Although the average between the 2 procedures was 66.6 days, the median was only 14 days:

  • 52% of the teeth were treated within 14 days
  • 30% of the teeth were treated within 15 to 59 days
  • 18% of the teeth were treated after ≥60 days

This gave the authors an opportunity to assess the question of timing with some ease.

The results showed no statistically significant difference in survival when the post/core was placed within the first 59 days; however, there was a statistically greater risk of needing retreatment, apicoectomy or extrac­tion in the group in which the post/ core had been placed at ≥60 days after completion of the endodontic therapy. The same result was found for timing of crown placement on the post/core. Teeth on which the crown was placed ≥60 days after the post/ core placement fared worse than did those having the crown placed sooner.

The authors further broke down their sample to determine the effect of placing post/core vs only core. They found that teeth treated with a post/core placement showed a higher rate of failure. In addition, they discovered that when the endodontic therapy was completed by a trained endodontist, there was less reported failure than there was for those teeth completed by general practitioners.

Conclusion

While these types of studies provided an opportunity to investigate a large number of treatments, they did not directly assess the quality of the treatment rendered, and there was a chance that the failure might not have been registered in the database because of coding issues or patients having lost their insurance coverage when the failure occurred. Thus, there was some risk of overestimating the total long-term retention of the treated teeth. There is, however, no question that this study confirmed that the sooner the final restoration is placed on an endodontically treated tooth, the better the tooth’s long-term prognosis.

Yee K, Bhagavatula P, Stover S, et al. Survival rates of teeth with primary endodontic treatment after core/post and crown placement. J Endod 2017; doi: 10.1016/ j.joen.2017.08.034.