Endo
Treatment Planning for the Future: Endodontics, Post and Core, and Periodontal Surgery -- or an Implant?
George S. Matosian DDS
George S. Matosian, DDS, is a clinical assistant professor
at the University of Southern California School of Dentistry and co-director
of the Odontic Seminar in San Diego.
Copyright 2003 Journal of the California Dental Association.
After the early years of unpredictable and problematic results, dentistry
now has dental implant procedures that mimic traditional restorative techniques
and offer an extremely high degree of success and predictability. Dental
practitioners now accept the validity of the use of endosseous dental
implants to replace the traditional fixed partial denture, especially
when the natural abutments for that fixed prosthesis have minimal or no
existing restorations.1 However, it is time to expand the use
of dental implants in day-to-day restorative treatment planning. Despite
every effort to provide superior care, the unavoidable cascade of events
seen in the "A.K." case history demonstrates the limitations
of dentists’ abilities when traditional therapies are inadequate to overcome
the weaknesses that patients present. Rather than rebuilding a badly compromised
but still "restorable" tooth, dentists now need to reconsider
their approach to its restoration. Given advances in implant therapy,
it is now appropriate to consider the "early" removal of marginal
teeth. Although dentists had no previous choice but to rely upon compromised
teeth as key elements in restorative plans, a more predictable and successful
result may be possible by their early replacement with one or more dental
implants. In many situations, a single-tooth implant offers improvements
in ease of restoration, preservation of alveolar bone, superior strength,
predictability, and survivability as compared with the natural tooth that
requires an elaborate rebuilding procedure following endodontic therapy.
In addition, the implant-supported restoration may frequently be more
economical, since initial costs are similar; and the weakened endodontically
posted tooth will very likely require follow-up care or removal at a later
time, increasing complexity and expense.
The A.K. case history illustrates a number of sophisticated, traditional restorative treatment procedures that remain in common use today. In the past, dentists were often obliged to rely on debilitated natural teeth to support a crown restoration, fixed bridge, or removable partial denture. A debilitated tooth has a guarded long-term prognosis as a restorative abutment, since all or most of the coronal tooth structure is lost, its root has a thin cross-section or is "hemi-sected" or short, or the tooth has a compromised periodontal attachment. Endodontics, periodontal therapy, and the placement of a post and core were regularly needed to restore these teeth prior to the final restoration. Even when well done, the final root and post "complex" remains an unavoidable weak link under our final restorations. When under routine functional load, let alone the stresses associated with being an abutment for a fixed or removable partial denture, such teeth are often subject to catastrophic failure.
Studies show that if adequate tooth structure remains in a posterior tooth after endodontics, a cast restoration is adequate to preserve its strength; and it can support a crown or serve as an abutment without the need for a post or post and core.2 This consideration remains valid. Endodontic posts provide no additional strength to the tooth and increase its risk of fracture.3 The risk of root fracture increases in teeth that have larger post spaces, thin root walls, or when short posts are used to support a core.4 Reports of post and core failures due to root fracture range from 3 percent to as high as 10 percent. Furthermore, loosening of posts is an even more common occurrence than root fracture, leading to additional endodontic post and final restoration failures.5
A comparison of the survivability of debilitated teeth to the success rates for single-tooth implant-supported restorations, shows significant improvements in implant survivability over natural teeth. Priest reports a 97.4 percent survival rate of single-tooth implant restorations and, even more importantly, a concomitant stability in the health of the untouched adjacent natural teeth in a 10-year retrospective study.1 This is highly significant because if a traditional fixed partial denture were to be placed, the potential need for subsequent therapy (typically endodontics due to pulpal stress or retreatment due to recurrent decay) would greatly increase overall treatment costs with time.6
Dental professionals must therefore recognize the fact that the preservation of debilitated natural teeth, no matter how "noble" a concept, may offer patients a poorer prognosis than the early removal of such teeth and their pre-emptive replacement with a dental implant. Treatment planning paradigms need to be updated to reflect these changes. Instead of routinely restoring debilitated and/or endodontically treated teeth, dentists need to evaluate them as follows:
* Teeth that have unusually enlarged root canal spaces or roots with thin peripheral walls are prone to root fracture when in function. These teeth should be removed and replaced with a dental implant so that the prosthesis they support will not be compromised later. This is of particular concern when these teeth are to be used for abutments for fixed or removable prosthetics to avoid the failure of the entire restoration and bone loss. The greater the functional load, the more likely this is to occur.
* Teeth that have little remaining coronal tooth structure should also be evaluated for removal and replacement with a dental implant unless there is significant bulk to the root. Proper post-endodontic restoration of a badly broken down tooth requires the use of a long post that is placed without weakening the walls of the remaining root structure or harming the apical seal. The greater the loss of coronal tooth structure and the shorter the root, the less resistance the post and core has to dislodgment, leading to the failure of the overlying crown or fixed partial denture.6
* Teeth with very poor crown-to-root ratios should also be considered for early removal and replacement if adequate bone support for a dental implant is available or can be developed without undue difficulty. While the ongoing loss of alveolar bone must be averted for successful implant placement, the literature also supports that 15 percent of teeth that require periodontal surgery prior to prosthodontic treatment will also require root-weakening endodontic therapy after restoration.7
* Long-span fixed partial dentures abutted on endodontically treated teeth often have a poor long-term prognosis. Instead, the placement of multiple implants will provide superior support to the arch and the separation of individual teeth, minimizing the complications associated with long-span restorations.
* Teeth that have adequate bulk to restore but do not respond to endodontic retreatment should be evaluated more critically than they have been in the past. Prolonged or ineffective healing will destroy needed alveolar bone and complicate future implant or other restorative procedures.
* The successful long-term restoration of an endodontically treated posterior tooth that has adequate coronal tooth structure can routinely be accomplished without the need for a post or post and core.6 However, if a tooth lacks coronal integrity, dentists must now also consider the effect that its debilitated condition will have on its long-term prognosis, and compare that to its prognosis were it to be replaced with a dental implant.
* Anterior areas present other issues, as the need for precise control of gingival architecture and the preservation of the gingival papillae are critical esthetic issues. When there is adequate tooth structure, the literature supports that a minimal restoration of the natural tooth is adequate.6 When implant replacement is required, a careful team effort between periodontist or surgeon and restoring dentist is indicated to ensure optimal anterior esthetics.
In conclusion, dentists become accustomed to those techniques that they believe will provide their patients with a high level of predictability and success. Their instincts direct them to preserve every tooth they possibly can, just as was done for patient A.K. However, dentistry must continually evaluate the merit of traditional methods and compare them to advances, so that dentists can offer their patients the benefits of proven technological innovations. The literature now offers significant substantiation that implant-supported restorations represent efficacious and effective improvements over the use of the traditional endodontic, post and core, and periodontal surgery (or crown-lengthening) techniques needed to rebuild badly compromised teeth as in the A.K. case history. Dentistry therefore needs to rethink its traditional approach to treatment planning for these teeth with a long-range perspective. As always, the dental practitioner needs to confer with his or her patient as to the consequences of treatment planning decisions. The challenge to dentists is to "look ahead" for their patients and, through an understanding and appreciation of the long-term potential that dental implant technology offers, recognize how and when treatment planning must change. This process will require dentists to expand their "comfort zones" and incorporate the use of dental implants at a far earlier point in their day-to-day restorative treatment planning.
References
1. Priest G, Single-tooth implants and their role in preserving remaining teeth. Int J Oral Maxillofac Implants 14:181-8, 1999.
2. Sorenson JA, Martinoff JT, Intracoronal reinforcement and coronal coverage: A study of endodontically treated teeth. J Prosthet Dent 51:780-4, 1984.
3. Troupe M, Maltz DO, Tronstad L, Resistance to fracture of restored endodontically treated teeth. Endodont Dent Traumatol 1:108-11, 1985.
4. Trabert KC, Kaputo A, Abou-Rass M, Tooth fracture -- A comparison of endodontic and restorative treatments. J Endodont 4:341-5, 1978.
5. Turner CH, Post-retained crown failure: A survey. Dent Update 9:193-202, 1982.
6. Goodacre CJ, Spolnik KJ, The prosthodontic management of endodontically treated teeth: A literature review. Part 1. Success and failure data, treatment concepts. J Prosthodont 3:243-50, 1994.
7. Bergenholtz G, Nyman S, Endodontic complications following periodontal and prosthetic treatment of patients with advanced periodontal disease. J Periodontal 55:63-8, 1984.
To request a printed copy of this article, please contact/George S. Matosian, DDS, 5565 Grossmont Center Drive, La Mesa, CA 91942-3020.
