Fundamentals of Restorability

By Gabriella Blazquez

At the heart of endodontics is a passion for saving restorable teeth which can be maintained as a part of a healthy dentition. By reviewing the key factors, which should be considered when accessing restorability, I hope to provide a concise guide on the management of teeth with questionable prognoses.

Patient Considerations:

First, it is critical that we have a holistic understanding of our patient. Their biology, behavior, financial status, and preferences can, and usually should, inform our treatment planning (1). Medical advances have increased the percentage of medically compromised patients we will see in our daily practice. The most prevalent condition is cardiovascular disease (CVD) followed by endocrine disorders, usually diabetes mellitus (DM)(2). By obtaining a complete medical history, performing a thorough physical examination, routinely taking vitals, and seeking medical consultations, when needed, we prepare ourselves to make informed decisions about the risk of dental procedures for individual patients.

In patients with a history of CVD we must focus on pain control, stress reduction, and the use of epinephrine in local anesthesia. Special attention should be given to patients currently taking antiplatelet, anticoagulant, and antihypertensive medications (3). For diabetic patients, morning appointments are advisable and the provider should confirm that the patient has eaten and has taken all scheduled medications. Diabetes predisposes patients to chronic inflammation, reduces tissue repair capacity, increases susceptibility to infections, delays wound healing, impairs bone deposition, and is strongly associated with periodontal disease. (12) Therefore, elective dental treatment may need to be delayed if the patient’s diabetes is poorly controlled. Patients with diabetes mellitus who have preoperative periradicular lesions have a reduced likelihood of success after endodontic treatment (13).  Diabetes mellitus may have a negative impact on the outcome of endodontic treatment, specifically with regard to periapical healing (14). However, implant placement in patients with poorly controlled diabetes has an unpredictable prognosis, and should be avoided when possible (4).

The clinician should consider the patient’s preferences, needs, attitudes, and motivation to undergo treatment and restoration of remaining dentition. Important behavioral considerations include the patient’s commitment to their oral hygiene, the cariogenicity of their diet, level of fluoride exposure, existence of parafunctional habits, and smoking history. Motivation for treatment as well as the patients’ ability or willingness to maintain care protocols and endure lengthy and/or involved procedures should be factored into treatment planning (1). The patient’s unique preferences surrounding their treatment should always carry substantial weight. At times expectations can be unrealistic and patient education and counseling is required.  Too often, financial limitations, including whether or not the patient is insured, can bring about a decision to extract a restorable tooth.

Evaluating of individual teeth:

Periodontal prognosis: Periodontal health and bone support are the foundation upon which any restored tooth will lie. Therefore it is essential for the provider to evaluate the remaining alveolar bone support and the patients’ ability to clean and maintain supporting tissues. These factors should be considered within the context of periodontal therapy, maintenance, as well as regenerative therapy, if applicable. Periodontal probing is an efficient and effective way to identify active periodontal disease. (15) Teeth with <30% bone support which cannot be cleansed or maintained without acute periodontal infections, are usually considered nonsalvagable (1).

Restorative prognosis: The ultimate success of endodontic treatment relies on the quality of coronal restoration (6) which is limited by the amount of coronal tissue loss. To maximize the likelihood of success, practitioners should aim to minimize the loss of sound dental structure, especially cervically, where a ferrule effect can be created (9). The presence of a “ferrule” enhances the biomechanics of a restored tooth, with a 1.5 to 2mm ferrule significantly increasing the fracture resistance of endodontically treated teeth (7). A ferrule refers to parallel walls of dentin, which extend coronally from the crown margin and serve to reduce stresses within a tooth (8). Teeth where a good ferrule cannot be achieved without compromising the support of adjacent teeth or the crown-root ratio are considered compromised and have high risk of being lost (1). Those without any remaining supragingival tooth structure or with loss of structure deep into the root dentin are generally indicated for extraction (1).

Endodontic prognosis: Certain endodontic factors such as canal calcifications, difficult isolation, resorptive pathology, anatomical variations in the root canal system, the need to retreat, existence of a post, or ledges and perforations can complicate treatment and diminish predictability (10). The presence of a periapical radiolucency, indicating a longstanding pathology, appears to lower the success rate of endodontic treatment (11). Teeth with failing endodontic treatment which cannot predictably be retreated are considered compromised and at high risk of being lost (1). Finally, teeth with vertical root fractures or one which has been retreated several times without resolution is generally considered nonsalvagable (1).

Functional considerations: Over-erupted and severely tipped teeth can sometimes be restored to the correct occlusal plane with enameloplasties, orthodontics, crown lengthening, and/or a partial or full coverage restorations. However, if the tooth cannot be restored into normal functional contact without severely diminishing the crown-root ratio or damaging the health of adjacent structures, it may not be in the patient’s best interest to invest in restoring it. If the tooth is so super-erupted or tilted that it cannot be restored to the correct occlusal plane, or it would interfere with the broader restoration of the arches, it should be extracted (1).

Strategic value of a tooth: To help patients peruse a healthy and functional dentition that lasts, we must also consider the strategic value of a given tooth within the context of the entire dentition. Teeth which can serve as abutments for removable partial dentures or fixed bridge prosthetics are particularly valuable. For example, the value of restoring and a second or third molar, which could serve as an abutment for and increase the stability of a removable partial denture, must be explained to the patient and considered in treatment planning. Additionally, patients are often highly motivated to save teeth in the aesthetic zone (10).

Clinical management of teeth with questionable prognoses begins with a thorough understanding of the patient and an assessment of the tooth’s periodontal, restorative, and endodontic prognoses. Additionally, we should consider both the function and strategic value of a tooth within the context of the entire remaining dentition. Endodontists can use these categories to evaluate the utility of rehabilitating natural teeth to long-lasting, healthy, and useful parts of patients’ dentition.

References:

1. Samet N, Jotkowitz A. Classification and prognosis evaluation of individual teeth–a comprehensive approach. Quintessence Int. 2009 May;40(5):377-87. PMID: 19582242
2. Bhateja S. High prevalence of cardiovascular diseases among other medically compromised conditions in dental patients: A retrospective study. J Cardiovasc Dis Res. 2012;3(2):113-116. doi:10.4103/0975-3583.95364
3. Margaix Muñoz M, Jiménez Soriano Y, Poveda Roda R, Sarrión G. Cardiovascular diseases in dental practice. Practical considerations. Med Oral Patol Oral Cir Bucal. 2008 May 1;13(5):E296-302. PMID: 18449113.
4. Rees TD. Endocrine and metabolic disorders. In: Patton LL, Glick M, editors. The ADA Practical Guide to Patients with Medical Conditions. 2nd ed. Hoboken, NJ: John Wiley & Sons, Inc.; 2016. p. 71-99.
5. Newman MG, Takei HH, Carranza FA. Carranza’s Clinical Periodontology, ed 10. St. Louis: Saunders Elsevier, 2006.
6. Gillen BM, Looney SW, Gu LS, et al. Impact of the quality of coronal restoration versus the quality of root canal fillings on success of root canal treatment: a systematic review and meta-analysis. J Endod 2011;37:895–902
7. Juloski J, Radovic I, Goracci C, Vulicevic ZR, Ferrari M. Ferrule effect: a literature review. J Endod. 2012 Jan;38(1):11-9. doi: 10.1016/j.joen.2011.09.024. Epub 2011 Nov 13. PMID: 22152612.
8. Stankiewicz N, Wilson P. The ferrule effect. Dent Update 2008;35:222–4.
9. Dietschi D, Duc O, Krejci I, Sadan A. Biomechanical considerations for the restoration of endodontically treated teeth: a systematic review of the literature–Part 1. Composition and micro- and macrostructure alterations. Quintessence Int. 2007 Oct;38(9):733-43. PMID: 17873980.
10. Yeng T, Messer HH, Parashos P. Treatment planning the endodontic case. Aust Dent J. 2007 Mar;52(1 Suppl):S32-7. doi: 10.1111/j.1834-7819.2007.tb00523.x. PMID: 17546860.
11. Sjogren U, Hagglund B, Sundqvist G, Wing K. Factors affecting the long-term results of endodontic treatment. J Endod. 1990 Oct;16(10):498-504. doi: 10.1016/S0099-2399(07)80180-4. PMID: 2084204.
12. Nagendrababu V, Segura-Egea JJ, Fouad AF, Pulikkotil SJ, Dummer PMH. Association between diabetes and the outcome of root canal treatment in adults: an umbrella review. Int Endod J. 2020 Apr;53(4):455-466. doi: 10.1111/iej.13253. Epub 2019 Dec 19. PMID: 31721243.
13. Fouad AF, Burleson J. The effect of diabetes mellitus on endodontic treatment outcome: data from an electronic patient record. J Am Dent Assoc. 2003 Jan;134(1):43-51; quiz 117-8. doi: 10.14219/jada.archive.2003.0016. PMID: 12555956.
14. Arya S, Duhan J, Tewari S, Sangwan P, Ghalaut V, Aggarwal S. Healing of Apical Periodontitis after Nonsurgical Treatment in Patients with Type 2 Diabetes. J Endod. 2017 Oct;43(10):1623-1627. doi: 10.1016/j.joen.2017.05.013. Epub 2017 Aug 10. PMID: 28803674.

Gabriella Blazquez is a third-year dental student at the University of Connecticut School of Dental Medicine. She has a passion for endodontics and plans to spend her career practicing, teaching, and researching the specialty. She spends her spare time hiking around New England with her two dogs, watching old movies, and baking cakes. Please feel free to reach out to her with any questions or comments at blazquez@uchc.edu.