Endocrowns: A Systematic Review

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Episode 40 introduced the endocrown from a foundational 2013 paper; this time we turn to a review that brings together 41 studies — 8 clinical and 33 in vitro — and asks whether the endocrown really is a dependable alternative to the post-and-crown. The answer is not the same for every tooth, and that is exactly where the clinical decision is made: molars, premolars and incisors are three quite different situations.

Key Points and Main Findings

• Molars: on badly damaged molars, the endocrown is a remarkably dependable treatment, with high survival rates in the short, medium and long term.
• The main cause of failure: unlike conventional crowns (with or without a post), which show more catastrophic failures such as root fracture, 71% of endocrown failures are loosening and debonding — which, fortunately, can be repaired and managed!
• Premolars: clinical studies have reported lower survival rates, and every failure involved loss of adhesion; in vitro studies, however, recorded fracture resistance comparable to post-retained crowns.
• Incisors: no clinical study is available, the in vitro studies are few and their results conflicting, and at present no clinical indication can be stated for them.

Golden Keys to a Successful Treatment

• Choosing the right material:
  • Nanofilled composite resins: with an elastic modulus similar to tooth structure, they absorb stresses well and reduce the likelihood of an irreparable failure.
  • Lithium disilicate ceramics: an excellent option with high esthetics and excellent adhesion (ceramics generally retain less plaque than composites).
• A flawless adhesion protocol: since the bulk of failures stem from debonding, following the bonding protocol precisely and using a material with high adhesion is vital.
• Cavity design: if the residual height of the pulp chamber walls is less than 2 mm, the risk of debonding rises; and rather than removing undercuts by cutting tissue away, it is better to block them out with suitable materials so that tooth structure and overall strength are preserved.
• The importance of the finish line form: providing a ferrule increases the fracture resistance of the endocrown, but the attempt to create one must not come at the cost of losing enamel (especially near the CEJ) (note that this is this paper's view only)

Final Conclusion

The endocrown is a fully dependable treatment, especially for molar teeth, provided that the principles of cavity design, the bonding protocol and the choice of material (such as nanocomposites or lithium disilicate) are observed carefully and to a high standard.

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