This article was published in Quintessence International, Vol. 30, Num. 12 1999

I. Major Factors Affecting the Prognosis of the Strategic Tooth

When is treatment futile? The question appears deceptively simple, but the answer is surprisingly complicated. Without some qualifications, the answer would also be far beyond the space constraints placed on the authors. For this reason, we will respond to the question with the following assumptions:

1. The dental practitioner has superb diagnostic, treatment planning, and treatment skills.

2. Posttreatment management of oral hygiene is excellent.

3. The involved tooth is a strategic tooth and, if successfully treated, would become a functioning component of the patient’s masticatory apparatus.

4. There are no systemic contraindications or economic restrictions affecting treatment.

The tooth, rather than the entire dentition, will be the focus of our concern. The hopeless, untreatable tooth of the new millennium is far different from its counterpart a half century ago. The advances since the 1950s and ‘60s in technology, biomaterials, delivery systems, surgical and nonsurgical therapies, scientific evidence, and access to continuing education have been remarkable. The modern dental practitioner can accomplish what his/her predecessor of a few decades ago would have considered impossible. But the hopeless tooth still exists.

There are two major factors that most commonly relegate a strategic tooth to the “hopeless” status: restorability and periodontal support. The tooth that cannot be restored or that has inadequate, unmanageable periodontal support is hopeless.

Restorability. With modern restorative materials and techniques, most teeth can be restored. Even teeth with carious lesions causing destruction of most of the coronal tooth structure are now restorable. Extensive coronal destruction frequently requires endodontic therapy, and/or crown-lengthening therapy.

Endodontic therapy. Restorative requirements often dictate endodontic treatment of the involved tooth. Restoration may require a post and core, superseding other considerations (eg, the status of the pulp) and rendering pulpal diagnosis essentially inconsequential. The post and core function collectively. The core replaces lost coronal tooth structure and provides retention for the crown. The post provides retention for the core. The post must be designed or selected to prevent the possibility of root fracture from insertional or functional forces. The crown restores function and protects the remaining root and coronal structure from decay and trauma.

Clinical dilemma. If a post and core are not required for restorative purposes, the most frequently encountered clinical dilemma involves the decision to treat or not to treat endodontically prior to coronal restoration. It is far easier to perform root canal treatment before crown preparation and fabrication, to allow better visibility, easier access, greater instrument control, and less likelihood of perforation, ledging, or other untoward treatment sequelae. In addition, patients generally respond negatively to the necessity of “making a hole” in their new crown, especially when informed of the possibility of porcelain fracture in porcelain-fused-to-metal crowns. The decision not to treat endodontically prior to restoration is usually based on one or more of the following factors: (1) the patient has no symptoms, (2) there is no periapical radiolucency, and (3) there is no pulpal exposure after caries removal. Each of these factors may lead to false conclusions and poor clinical decisions that may be regretted later.

Symptoms. It is essential to carefully analyze all subjective information and objective findings to obtain an accurate diagnosis of the pulpal status. If the diagnosis is either pulpal necrosis or irreversible pulpitis, endodontic treatment is indicated. If the diagnosis is questionable (ie, between irreversible and reversible pulpitis), the experienced practitioner will wisely decide to initiate endodontic treatment. If symptoms such as moderate to severe thermal sensitivity and/or masticatory sensitivity exist, endodontic treatment is clearly indicated.

Pulpal necrosis presents many clinical faces and therefore can be a real challenge to diagnose. Pulpal necrosis can cause such severe, spontaneous pain that the patient seeks immediate palliative treatment (many times in the hospital emergency room). It can also present with no symptoms and no prior history of symptoms. Most practitioners have observed the latter by discovering an obvious periapical radiolucency associated with an asymptomatic tooth. When apprised of this objective finding, the patient often has difficulty believing that a problem exists. Therefore, the absence of symptoms is not adequate justification for the decision not to perform endodontic treatment prior to full coronal coverage.

Periapical radiolucency. The absence of a periapical radiolucency does not indicate that there is no periapical inflammation resulting from pulpal breakdown. The presence of a radiolucency suggests pulpal necrosis with extension of the pulpal disease into the periapical tissues (the most common of several differential diagnoses requiring evaluation).

Radiographic evidence of periapical bone loss does not appear until bone destruction occurs at the junction of cancellous and cortical bone.1 The anatomic relationship of the root apex to the adjacent buccal or lingual cortical plate dictates the amount of bone loss that must occur before it is observable radiographically. In maxillary lateral incisors, mandibular anteriors, and certain roots of maxillary and mandibular premolars and molars, periapical bone loss can be considerable without radiographic evidence of a radiolucency.

The presence of a periapical radiolucency with diagnostic evidence of pulpal necrosis indicates the need for endodontic therapy. The absence of a periapical radiolucency means nothing.

Pulpal exposure. There is a common misconception within the dental profession that the only important dimension of a carious lesion is the depth of penetration. This reflects a lack of understanding of pulpal pathosis and its etiology. It also suggests that many dentists do not understand that pulpal injuries are cumulative. The fact that there is no pulpal exposure is meaningless.

Pulp never returns to a normal state after the first carious assault. Further pulpal injury occurs with cavity preparation and with insertion of any restoration replacing coronal tooth structure. Each succeeding carious attack, caries removal, and restoration adds its damaging effects on the pulp. As a result, pulp that has suffered through several carious lesions and several restorations may not be capable of withstanding the damage inherent in crown preparation. (There should be no delusion that coronal preparation of any type is not damaging to the pulp.) Unfortunately, obvious symptoms and signs of pulpal breakdown, a result of cumulative injuries over many years, may not become clinically evident until long after full coronal coverage.

The wise practitioner considers the cumulative effect of injuries to the pulp (similar to the cumulative damage of irradiation to tissues) when making the appropriate clinical decision regarding the need for endodontic therapy prior to full-coverage restoration of the tooth with moderate to severe coronal destruction.

Success rate in modern endodontics. The success of endodontic therapy in the new millennium will be approaching 95%, a phenomenally high rate in comparison to several decades ago. The technological boom in endodontics has provided the general dentist and the specialist with methods and instruments that allow successful treatment of teeth with calcified chambers, calcified canals, severe root curvature, ledging, resorptive defects, perforations, and canal blockage. With enhanced vision, direct lighting, use of ultrasonics, nickel-titanium mechanical and hand instruments, and multiple delivery systems for obturation, almost all teeth requiring endodontic therapy can be successfully treated. In fact, the two primary causes of endodontic failure are actually due to restorative and periodontal failures.

Crown-lengthening therapy. With extensive carious destruction of coronal tooth structure, crown lengthening procedures are frequently indicated. The purpose is to allow sufficient exposure of tooth structure to prevent crown margins from impinging on the biologic width of the cervical attachment apparatus. This may be accomplished by periodontal surgery or orthodontic extrusion.

Periodontal health is essential for long-term success of the restored tooth, and the effect of the planned restoration on the cervical attachment apparatus must be considered. Violation of the biologic width by the crown margins invites failure due to the increased potential for progressive periodontal disease. This problem is easily solved by periodontal crown-lengthening surgery, which essentially moves the cervical attachment apparatus apically prior to crown preparation. The same result can be obtained by orthodontic extrusion, but this treatment is more complicated and requires a longer period of time.

Periodontal support. Periodontal disease may cause destruction of the periodontal support of a tooth to the extent that it becomes a hopeless cause. But modern treatment and maintenance capabilities have made tremendous advances in allowing the severely damaged, periodontally involved tooth to continue as a functioning member of the masticatory apparatus.2 The periodontally hopeless tooth, similar to the restoratively hopeless tooth, will be quite different in the new millennium as compared to its counterpart in the mid-20th century.

Major factors affecting prognosis. Among the determinants most commonly used in the assessment of the prognosis for a tooth with a diseased periodontium are: (1) pocket depth, (2) pattern and degree of bone loss, (3) degree of mobility, and (4) crown-root ratio. In addition, the practitioner must be able to identify and eliminate (or control) the etiologic factors responsible for the periodontal destruction. (Vitality status of the pulp is a potential etiologic factor that always requires evaluation.) Pocket formation, bone loss, mobility, and an unfavorable crown-root ratio are reflections of the normal progression of periodontal disease.3 If the history related to each of these factors can be determined, the rate of progression of the disease and the age of the patient can be used as important considerations in determining the prognosis. The older the patient, the more favorable the prognosis for any degree of periodontal destruction.

Periodontal pockets. The depth, size, and location of periodontal pockets provide a preliminary assessment of the extent of disease. In general, the deeper the pocket, the poorer the prognosis. If the deeper pocket accurately reflects greater loss of alveolar bone, the problem is more serious. Pockets associated with single-rooted teeth usually respond to treatment better than those associated with multirooted teeth, especially if the furcation area is involved. The presence of furcation involvement does not indicate a hopeless prognosis. However, involvement of the furca area by periodontal disease causes two significant problems: (1) limited access for scaling and root planing and for performing surgery and (2) limited access for plaque removal by the patient. The more accessible the pocket for treatment, the better the prognosis. Deep proximal and circumferential intrabony defects do not respond predictably to treatment.

Bone loss. The greater the bone loss, the more guarded the prognosis. As bone loss approaches and exceeds 50% and as the pattern of bone loss becomes more irregular, the prognosis worsens. Irregular, vertical, and troughlike intrabody defects adversely affect prognosis, especially if the interradicular bone of a furcation is involved. If the roots are widely spread and root concavities are minimal, furcation involvement is more amenable to root resection procedures (after endodontic therapy when possible) and other types of corrective surgery. If the entire interradicular septum has been lost or if the roots converge or fuse at or near the apices, the prognosis is hopeless.4

In the past decade, a new form of periodontal treatment has proved to be remarkably successful. Many teeth previously regarded as hopeless are salvageable via guided tissue regeneration (GTR). Badly involved class II furcation involvements, large three-walled intrabony defects, and osseous craters that were nontreatable have become predictably treatable. Recent advances with extensive GTR procedures have made most two-walled infrabony defects routinely treatable. Multiple-tooth GTR procedures are becoming increasingly successful; even groups of teeth with more than 50% loss of attachment can be maintained with regenerated support.4

An isolated vertical intrabony defect may result from a fracture extending vertically and apically along the root (vertical root fracture). This type of fracture may be due to occlusal trauma (especially in teeth with restorations involving the mesial and distal marginal ridges), post placement, or excessive compaction (condensation) forces during root canal treatment.4,5 These are difficult to diagnose because they mimic other conditions, including failed root canal treatment and periodontal disease. If only one root of a multirooted tooth is involved, root resection is an option. Otherwise, vertical root fractures have a hopeless prognosis.

Mobility. Teeth with deep pockets and bone loss have a more favorable prognosis if they are stable rather than mobile. Mobility may be caused by inflammatory changes in the periodontal ligament, trauma from occlusion, or lo ss of alveolar bone. Mobility caused by inflammation and traumatic occlusion are often easily corrected, but mobility caused by loss of alveolar bone support presents a much greater problem. Teeth with 50% loss of attachment and 2 to 3 degrees of mobility have a very guarded prognosis, perhaps hopeless. However, if the cause of mobility can be eliminated and the mobility can be controlled (by splints, fixed prostheses, etc), then the prognosis is better. In general, a direct association exists between increasing mobility and worsening prognosis. If a tooth is depressible, the prognosis is usually hopeless.

Crown-root ratio. The more favorable the crown-root ratio, the better the tooth can withstand masticatory forces and the better the prognosis. Teeth with short, slender, or tapering roots have a poorer prognosis than those with long and broad roots. Multirooted teeth usually resist traumatic forces better than single-rooted teeth. Flared molar roots give better support than fused, conical roots. Broad occlusal tables and large crowns can contribute to increased mobility. The support of the tooth is determined by the height of the alveolar crest and the length and shape of the root. Canines can withstand loss of support better than lateral incisors by virtue of their longer roots and root concavities. Maxillary first premolars show early mobility because of the tapered roots.3 Some patients have teeth with short roots and others have root resorption, both of which may be the result of orthodontic therapy. Such teeth are less resistant to excessive occlusal forces.

Assessing loss of periodontal support. It is apparent from this all-too-brief review of the problems inherent in the loss of periodontal support that the clinical decision to declare a tooth hopeless is not an easy call. The variables of periodontal disease are numerous when faced with determining the long-range (another variable) prognosis of a given tooth. The interrelationship of the four major factors affecting prognosis is very obvious. All are essentially a form of loss of attachment (loss of periodontal support) and a method of measuring the potential for future maintenance and function.

Summary. The decision to place a tooth in the hopeless category is by no means a simple one. There is always the possibility of being wrong, the possibility that this tooth may prove to be the exception and, against all odds, survive as a functioning component of the masticatory apparatus. These are the decisions that make us dentists rather than technicians.

References

1. Bender IB, Seltzer S. Roentgenographic and direct observation of experimental lesions in bone. II. J Am Dent Assoc 1961;62:708–716.

2. Wilson TG, Kornman KS, Mellonig JT, Brunsvold MA. Treating aggressive forms of periodontal disease. In: Wilson TG, Kornman KS (eds). Fundamentals of Periodontics. Chicago: Quintessence, 1996:389–421.

3. Grant DA, Stern IB, Listgarten MA (eds). Periodontics, ed 6. St Louis: Mosby, 1988:573–591.

4. Hall WB. Decision Making in Periodontology, ed St Louis: Mosby, 1998:70–75.

5. American Association of Endodontists. Cracking the cracked tooth code. Endodontics, Colleagues for Excellence 1997;Fall/Winter:1–8.

For reprints contact:

Dr John W. Harrison,

Department of Restoratice Sciences,

Baylor College of Dentistry,

PO Box 660677,

Dallas, Texas 75266-0677.

Fax: 214-874-4544.

II. Retrain or Extract: The Decision Process

When does a tooth become “hopeless,” and when is further treatment no longer a viable option? When is it time to cut our losses and make the decision to extract the questionable tooth? Becker et al1 suggest that if at least two of the following conditions exist, then a tooth is hopeless and further treatment is futile: (1) loss of bone support over 75%, (2) probing depths greater than 8 mm, (3) class III furcation involvement, (4) class III mobility with movement in the mesial, distal, and vertical directions, (5) a poor crown-root ratio, (6) root proximity with minimal interproximal bone, (7) evidence of horizontal bone loss, or (8) a history of repeated periodontal abscess formation.

What about the tooth with a horizontal or vertical fracture? What about the tooth that does not lend itself to endodontic or restorative procedures? Is it a tooth that the patient has neither the desire nor the money to retain? Webster’s dictionary defines hopeless as “having no expectation of, or showing no sign of, a favorable outcome.” The prognosis of a tooth is defined as the prediction of the duration, course, and termination of a disease and the likelihood of its response to treatment.2 It then becomes the responsibility of the dentist to decide the prognosis of the tooth, determine if it is truly hopeless, and make an educated recommendation to the patient.

Everyday, the practicing dentist must make a decision as part of the diagnosis and treatment planning process, whether it is for a new patient, a patient who has been with the practice for many years, or for the emergency patient for whom the decision must be made quickly. What are the guidelines for deciding to treat and maintain or to stop the progression of the disease and extract the tooth?

Patient involvement. Sometimes the decision is easy. Patients who show very little motivation by exhibiting poor oral hygiene or chronically missing appointments may be poor candidates for extensive, heroic types of treatment. Third-party payers may also be a deciding factor due to their policy on which procedures can be reimbursed. The responsibility, therefore, falls on the patient, who may be either unwilling or unable to pay for the procedure without outside help. This, however, does not relieve the professional from his or her obligation to inform the patient of the various treatment options, the cost and possible sequelae from each of the options, and to represent the patient’s best interest to any third party.

As the ultimate decision maker, the patient may decide that the risk/benefit ratio is not in his or her best interest, and decide on less-than-ideal treatment. On the other hand, some patients will wish to maintain the tooth no matter how hopeless it may be. The professional should not let practice productivity, practice setting, or environment influence his or her recommendations, but let standard of care and professional judgment guide the recommendations on the proper treatment.

In an ideal world, dental professionals would prefer to rely on scientific research to guide them in this decision-making process. Unfortunately, many times our “best guess” guides us in our recommendation since this process often becomes an art determined by experience rather than a science determined by research.

Another deciding factor in treatment selection should be patient compliance.

Even the most routine treatment can become a problem to complete satisfactorily when the patient exhibits a difficult or uncooperative personality. Claustrophobia or fear of radiation, pain, or needles can impair a patient’s ability to behave well in the dental office.3 This may make any treatment difficult and deem the patient a poor candidate for any extensive treatment, because it may lead to an uncertain outcome with unknown longevity.

In a recent study by Reich and Hiller,4 it was found that from the patients’ perspective, pain was usually the major reason for seeking extraction of the offending tooth. When the dentist was consulted, periodontal disease was the most frequent cause of tooth extraction for people over 40 years of age, while for patients below 40 years of age, caries and third molar extractions were the most frequent reasons for exodontia.

Strategic value. Ultimately, one of the first decisions that must be made is the strategic value of a tooth. This will have a bearing on whether the tooth is retained or extracted. For example, a third molar in an arch with many missing teeth may need to be saved so that it can be used as an abutment for a partial denture. A third molar with an otherwise full complement of teeth may not be worth the time or effort to restore, and the decision to extract would be the correct decision.

This same decision process can be made for other strategic abutment teeth. A full denture is a poor substitute for natural teeth; however, an average patient is usually satisfied with a maxillary complete denture after some period of adjustment. The same cannot be said for many mandibular complete dentures. A mandibular complete denture is much more difficult to adapt to, and every effort should be made to maintain strategic abutment teeth as long as possible to provide retention for a partial denture. This is especially true if the patient is a poor candidate for a dental implant.

The next area to consider is the restorability of the tooth. Sometimes the decision is made to rebuild a badly broken-down tooth with some kind of post and core (ie, cast gold, prefabricated, or one of the new flexible systems). This would be the wrong decision if a lack of tooth structure precludes an adequate ferrule. The ability to create a ferrule of 1.5 to 2 mm in height with 1 mm of dentinal wall thickness in the area of greatest resistance is the key to long-term predictability of the restoration. The inability to do so may mean the tooth should be removed, especially in a mouth with heavy occlusal function.5

Vertical fractures. Another diagnostic problem is the fractured tooth. Most vertical fractures into the root make the decision easy: The tooth should be considered hopeless and scheduled for extraction. Experience shows that only rarely will any heroic attempt to save this tooth be successful.6

The signs and symptoms of the fractured tooth may mimic those of periodontal disease or a failed root canal treatment, complicating diagnosis. An isolated, narrow, and sharply defined periodontal pocket, which prevents the probe from moving laterally, usually indicates a late-stage vertical fracture. This is unlike the broad pocket associated with periodontal disease. The most frequent clinical and radiographic sign and symptom of a vertical fracture is the presence of a periodontal pocket.

Many of the teeth referred to the endodontist for treatment are actually fractured teeth that should be considered for extraction. If, at the time of the endodontic access, it is noticed that the fracture extends into the pulpal floor, then the prognosis is poor and further treatment is questionable.

With the present knowledge in the field of endodontics, there are few true contraindications to endodontic treatment. Severe root caries, furcation caries, severe internal or external resorption, and poor crown-root ratio present problems with restoration and may contraindicate endodontic treatment. Calcified or blocked canals used to be problems for treatment, but now with use of a microscope, these situations are less troublesome. This is an area where general dentists may wish to refer the patient to a specialist.

Periodontal disease. Determining the prognosis for a periodontally hopeless tooth is difficult. If a tooth has little periodontal involvement and is initially given a good prognosis, then dentists are generally correct in their projections. However, when any other prognosis (fair, poor, questionable, or hopeless) is initially assigned, projections are often incorrect. 7 In fact, many teeth remain in function for long periods of time even when initially classified as hopeless.

Several factors must be taken into consideration during the initial evaluation of the patient: (1) a deep initial probing depth, (2) severe initial furcation involvement, (3) malposition of the tooth, (4) initial unsatisfactory root form, (5) initial endodontic involvement, (6) patient history of smoking or diabetes, (7) parafunctional habits without using a biteguard, (8) poor oral hygiene, and (9) infrequent recall visits. If these factors are ignored, the periodontal condition may deteriorate more rapidly than anticipated.

Wojcik et al8 found that periodontally hopeless teeth that are retained do not significantly affect the proximal periodontium of adjacent teeth when treated with scaling and root planing, oral hygiene instructions, occlusal adjustments, and periodontal surgery. Their success was correlated to supportive periodontal treatment at least twice per year. However, without periodontal treatment, retention of hopeless teeth has a destructive effect on the periodontium of adjacent teeth. 9

Many teeth previously regarded as hopeless due to their periodontal condition are now salvageable by means of guided tissue regeneration (GTR). New surgical procedures make it more practical to retain the marginal tooth, even some teeth with badly involved class II furcation, large three-walled infrabony defects, and osseous craters that had been previously untreatable. A recent study evaluated clinical outcomes 4 to 8 years after surgery and found that GTR is a predictable and effective option for the treatment of severely compromised abutments.10

In addition, chlorhexidine-containing mouthwashes, new formulations of toothpaste that reduce the bacterial insult, and powered toothbrushes make it easier to retain the tooth through improved home care. These aids are available to patients who are motivated to use them and who want to maintain those teeth with questionable prognosis.

In some cases, it may be better to extract a questionable tooth and leave a larger amount of natural bone. The process of bone loss around periodontally compromised teeth diminishes the chances of successful implant placement. This argument for early extraction can be made because the predictability of implants has increased. The cumulative success rate of implants was reported in one study at 98.9% after 10 and 15 years.11 Another study reported a success rate of 95.5%.12 These are very impressive results and make implants a viable part of any treatment decision, if sufficient bone is available for implant placement.

Summary. It is difficult to give up attempts to save a tooth and decide to extract. Sometimes the decision is easy because experience allows the dentist to evaluate the patient and the situation and make an educated prognosis for the tooth. The thought process is extremely involved and many variables must be taken into consideration, some of which the dentist has very little control over. The process was much less involved when there were fewer options available to the patient and the dentist.

Teeth in themselves are very rarely hopeless; it is the desires of the patient, the expertise of the dentist, and the conditions of the oral environment that lead to a hopeless prognosis. A tooth can be moved to another place in the mouth or even into another patient’s mouth, and the treatment decision changes, making it not as hopeless. The wish of the patient is usually the final, determining factor for how treatment is carried out. Patients make the decision whether to spend their time and money to save the tooth with extraordinary effort or whether to cut their losses and give up on the tooth.

References

1. Becker W, Berg L, Becker BE. The long-term evaluation of periodontal treatment and maintenance in 95 patients. Int J Periodontics Restorative Dent 1984;4(2): 54–71.

2. Carranza F, Newman M. Clinical Periodontology, ed 8. Philadelphia: Saunders, 1996:390–398.

3. Cohen S, Burns R. Pathways of the Pulp, ed 7. St Louis: Mosby, 1998:62–63.

4. Reich E, Hiller KA. Reasons for tooth extraction in the western states of Germany. Community Dent Oral Epidemiol 1993;21:379–383.

5. Spear F. When to restore, when to remove: The single debilitated tooth. Compendium 1999;20:316–328.

6. Weine F. Endodontic Therapy, ed 5. St Louis: Mosby, 1996:5–8.

7. McGuire M. Prognosis versus actual outcome: A long-term survey of 100 treated periodontal patients under maintenance care. J Periodontol 1991;62:51–58.

8. Wojcik MS, DeVore CH, Beck FM, Horton JE. Retained “hopeless” teeth: Lack of effect periodontally treated teeth have on the proximal periodontium of adjacent teeth 8 years later. J Periodontol 1992;63:663–666.

9. Machtei EE. Hopeless teeth without periodontal treatment jeopardize adjacent teeth. J Periodontol 1989;60:512–515.

10. Cortellini P, Stalpers G, Pini Prato G, Tonetti M. Long-term clinical outcomes of abutments treated with guided tissue regeneration. J Prosthet Dent 1999;81: 305–311.

11. Lindquist LW, Carlsson GE, Jemt T. A prospective 15-year follow-up study of mandibular fixed prostheses supported by osseointegrated implants. Clin Oral Implants Res 1996;7:329–366.

12. Nevins M, Langer B. The successful application of osseointegrated implants to the posterior jaw: A long-term retrospective study. Int J Oral Maxillofac Implants 1993;8:428–432.

For reprints contact:

Dr James F. Simon,

Department of Operative Dentistry,

University of the Pacific, School of Dentistry,

2155 Webster Street,

San Francisco, California 94115.