18 Nov A Review of Tooth Restoration following Root Canal Therapy
A Review of Tooth Restoration following Root Canal Therapy
A literature review
Based on: An Endodontic Restorative Update. Oral Health. 2015 May:105 (5). Sas, GL.
Given the prevalence and success of implants in dentistry, accurately assessing the restorability of teeth prior to subjecting patients to expensive, time consuming and occasionally uncomfortable treatment is critical. Because the long-term success of endodontically (root canal) treated teeth is largely determined by the subsequent restorative treatment, dentists must be acutely aware of those factors which either improve or compromise a tooth’s long-term prognosis.
Accessing the tooth’s root canal system:
When a root canal system is accessed through the chewing surface of the tooth, the focus must be on conserving as much tooth structure as possible. Adhesive dentistry eliminates the need for gross mechanical retention features and allows for less tooth removal, improving the ability to predictably restore the root canal treated tooth to long-term function.
Sealing the tooth and rebuilding the substructure (the core):
Placing a filling, or core, into and onto a tooth immediately at the time that the root canal is sealed and filled optimizes the seal of the root canal system, a critical step in ensuring longevity of the tooth. The immediate build-up of a tooth becomes an extension rather than invasion of the endodontic seal (which occurs when the placement of a core is delayed).
Should a post be placed for added strength/retention?
The function of a post in restoring an endodontically treated tooth is strictly to retain a core/build-up when extensive loss of tooth structure has occurred. To maintain a long-term seal of the endodontic material when placing a post, 4-5mm of gutta percha (the root canal filling material) should be preserved at the tip of the tooth root. Although metal posts do not reinforce the strength of a root, fiber posts have been shown in recent literature to increase root fracture resistance. Further, if a rubber dam is used during post placement, the chances of developing a post-operative infection leading to root canal failure is greatly reduced. Having 1.5-2mm of natural tooth circumferentially around a core when a post is placed is important for long-term success of the final restoration.
Crowns are King!
At a 9 year follow-up exam, teeth with cuspal coverage (crowns) had 6 fold greater survival rate compared to teeth without cuspal coverage.
A conservative access opening into a tooth’s root canal system couple with immediately bonding a core into the tooth will greatly improve long term tooth retention following root canal therapy. If a post is required, due to extensive loss of tooth material, a fiber post ideally should be bonded while ensuring that a rubber dam is in place and 1.5-2mm of circumferential tooth structure is present. A full coverage crown is the final restoration of choice for a root canal treated tooth to restore it to optimal function for the longest predictable amount of time.