Compromised endodontically treated teeth with minimal tooth structure can be a challenge to restore. Traditional approaches of a prefabricated post and core or cast post and core have worked well.

However, there are instances in which a post and core may be especially difficult or not feasible for a tooth. The endocrown provides an alternate approach for saving and restoring these compromised teeth.

What is the endocrown? The concept was first introduced by Bindl and Mormonn in 1999, when they defined the endocrown as “ceramic restoration workpieces compromising the entire crown and an integrated, apically protruding retention part.”1

In their research, Bindl and Mormonn looked at 19 cases (four premolars and 15 molars) in which an endocrown was utilized. They found that after 28 months, 95% of the restorations were successful and failures were only due to secondary caries.

Intaglio surface of the endocrown, showing the portion that protrudes into the pulp chamber.
Figure 1: Intaglio surface of the endocrown, showing the portion that protrudes into the pulp chamber.

Since the early work on endocrowns was published by Bindl and Mormonn, a host of other studies have looked at preparation design for endocrown restorations. When preparing a tooth for an endocrown, a 2-mm occlusal reduction with extension into the pulp chamber is required.

Both a shoulder and a chamber finish line have been suggested in the literature,2, 3, 4 with the extension into the pulp chamber protruding approximately 2mm into the chamber.5 Minimal retention is present and thus these restorations must be bonded in place with a resin cement.

Endocrown restorations can be designed and fabricated using CAD/CAM technology and delivered in a single-visit appointment. Fabricating a provisional can be a challenge due to the lack of traditional retentive features present in an endocrown preparation. Studies performed that have involved fabricating a provisional for an endocrown preparation have utilized various materials, including Cavit-1 and acrylic-based provisional materials.6

Clinical image of a patient with a compromised, endodontically treated number 31.
Figure 2: A young patient presents with a compromised, endodontically treated #31. The patient is too young to consider an implant and the decision was made to save #31.
Endocrown prep with shoulder finish line and extension into the pulp chamber.
Figure 3: Endocrown prep with shoulder finish line and extension into the pulp chamber.
Delivery of endocrown number 31.
Figure 4: Delivery of endocrown #31.
Post-op radiograph #31 showing the endocrown result.
Figure 5: Post-op radiograph #31 showing the endocrown result.

Early results have shown that the endocrown has a high success rate, especially in molar teeth. A seven-year study comparing traditional crowns on endodontically treated teeth with endocrown restorations found success rates of 99.78% for traditional crown restorations and 98.66% for endocrown restorations.7 Also, a retrospective study looking at severely broken-down teeth with endocrowns found a survival rate of 99.0% and success rate of 89.9%.8

The endocrown is a unique type of restoration that has been shown to be predictable in restoring complex endodontically treated teeth and is yet another option to consider when developing a treatment plan to restore endodontically treated teeth.

Andy Janiga, D.M.D., is a contributor to Spear Digest.

References

  1. Bindl, A., and Mormann, W.H. “Clinical evaluation of adhesively placed endo-crowns after 2 years—preliminary results.” J Adhesive Dent: 1999: 1 225-265.
  2. Fages, M., et. al. “Chairside computer-aided design computer aided-manufacture all-all-ceramic crown and endocrown restorations: A 7-year survival rate.” Int J Prosthodont 2017; 30: 556-560
  3. Chang, C.Y., et al. “Fracture resistance and failure modes of CEREC endo-crowns and conventional post and core-supported CEREC crowns.” J Dent Sci 2009: 4 (3): 110-117
  4. Biacchi, G.R., et al. “The endocrown: An alternative approach for restoring extensively damaged molars.” J Esthet Restor Dent. 2013: 25 (6): 383-390.
  5. Hayes, A., et al. “Effect of endocrown pulp chamber extension depth on molar fracture resistance.” Oper Dent: 2017: 42 (3): 327-334.
  6. Biacchi, G.R., et al. “The endocrown: An alternative approach for restoring extensively damaged molars.” J Esthet Restor Dent. 2013: 25 (6): 383-390.
  7. Fages, M. et al. “Chairside computer-aided design/computer-aided manufacture all-ceramic crown and endocrown restorations: A 7-year survival rate.” Int J Prosthodont 2017; 30: 556-560
  8. Belleflamme, M.M. et al. “No post-no core approach to restore severely damaged posterior teeth: An up to 10-year retrospective study of documented endocrown cases.” Journal of Dentistry: 2017: 63: 1-7.

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Comments

Commenter's Profile Image Matthew M.
March 31st, 2021
I like this concept but I was wondering if there is good data on the use of PFM or gold when there is a lack of enamel to bond to?
Commenter's Profile Image Andy J.
April 1st, 2021
Hi Matthew. Thanks for reading the article, and for your question. There are case reports of PFM crowns being used as endocrowns. However, with the lack of retentive features in the preparation, bonding a ceramic endocrown has been seen to be the most predictable option for these restorations.