Crowns improved survival of root treated teeth

Root canal treatment (RoCT) is a common treatment and it is believed that the tooth may be weakened during access preparation. Studies have suggested that crowning root treated teeth increased survival.

The aim of this review from the Canadian Agency for Drugs and Technologies in Health (CADTH) was to evaluate the clinical and cost-effectiveness of dental crowns for root canal treated teeth.

Three questions were to be addressed:

What is the clinical-effectiveness and prognosis of placing crowns on endodontically treated teeth?
What is the cost-effectiveness of placing crowns on endodontically treated teeth?
What are the evidence-based guidelines for placing crowns on endodontically treated teeth?

Methods

Searches were conducted in PubMed, The Cochrane Library, ECRI, Canadian and major international health technology agencies. Health technology assessments, systematic reviews, meta-analyses, randomized controlled trials, non-randomized studies, economic evaluations and evidence-based clinical guidelines in English were considered. A single review selected studies. The AMSTAR checklist was used to assess systematic reviews with non-randomised studies being assessed using the Downs & Black checklist. A narrative summary of the findings was presented.

Results

7 studies (3 systematic reviews, 4 non-randomised) were included assessing the effectiveness of crowns on RoCT teeth.
A narrative summary of each of the 7 identified studies is presented.
No evidence-based guidelines or cost-effectiveness studies were identified.

Conclusions

The authors concluded:

The available evidence suggests that the short term survival (2 to 3 years) of root canal treated teeth restored with crowns or direct fillings is comparable. On the long term however, the evidence suggests that root canal treated teeth have better survival rates at 10 and 20 years after treatment.

Comments

This rapid review from the CADTH helpfully pulls together the available evidence on this question. The authors summarise their appraisals and findings of each of the included reviews. The Cochrane review by Fedorowicz et al (Dental Elf – 18^th May 2012) was the most methodologically sound but that only included a single study and found insufficient evidence supporting or refuting the use of crowns to restore root canal treated premolars. The other included studies suggest good survival for crowned RoCT teeth, however they have a have a number of methodological weaknesses, which need to be considered when assessing the findings. The authors also highlight that the study population did not include patients from high-risk populations and risk of caries was not evaluated as an outcome in included studies. This may have implications for the generalisability of the findings.