Introduction
The management of impacted third molars (M3s) or wisdom teeth is a decision encountered by oral and maxillofacial surgeons (OMSs) daily. The decision-making is usually very straightforward, owing to the presence of disease. A challenging management decision is how to manage the asymptomatic, disease-free wisdom tooth. For these types of M3s, the treatment is essentially a binary choice: (1) operative treatment (eg, extraction) or (2) retention.
Management (ie, extraction versus retention) of the asymptomatic, disease-free wisdom tooth is fiercely controversial, with avid proponents of each treatment option. Because of the risk of future disease, the American Association of Oral and Maxillofacial Surgeons historically advocated “… that wisdom teeth be removed by the time the patient is a young adult to prevent future problems and to ensure optimal healing.” The American Public Health Association (APHA) rejects this strategy. APHA “opposes prophylactic removal of third molars, which subjects individuals and society to unnecessary costs, avoidable morbidity, and the risks of permanent injury.” However, the management of most asymptomatic, disease-free wisdom teeth lies somewhere between these two polar views. The author recommends that wisdom teeth be evaluated by the time the patient is a young adult to ensure optimal, patient-oriented management.
The traditional evidence-based tool to address a clinical dilemma is the critical appraisal exercise (CAE). The CAE has 4 elements: (1) asking a relevant clinical question, (2) reviewing the literature, (3) assessing the validity of the best information available and answering the clinical question, and (4) applying the findings to enhance patient care. The relevant clinical question for this article is: Among patients with asymptomatic, disease-free M3s, do those patients who choose to retain their M3s, when compared with those who elect M3 removal, have “better” or “different” outcomes? “Better” outcomes primarily include avoiding the costs and risks of an operation. These outcomes, however, are short-term benefits. There are no guarantees that avoiding an operation today assures no operation in the future. As such, the short-term benefits of M3 retention are tempered by the tangible, but unknown, risk for M3 removal at some point in the patient’s lifetime with its associated costs and risks.
In executing the second and third steps of the CAE, namely, reviewing and assessing the literature, the author identified a Cochrane systematic review that addressed the clinical question. The reviewers concluded that “no evidence was found to support or refute routine prophylactic removal of asymptomatic impacted wisdom teeth in adults.” Well-meaning advocates of both management strategies have used this review to support their positions.
The final step of the CAE is to apply the findings to provide and enhance patient care. However, in the absence of good evidence to support either management position as the predominant strategy, what is the clinician (or policy maker or payor) to do? Evidence-based clinical decision-making is not using the best theoretical evidence to make decisions. For example, without one or more randomized clinical trials, Cochrane reviewers commonly conclude that no recommendation can be made owing to inadequate evidence, leaving the clinician at a loss. Evidence-based clinical decision making is characterized as providing care given the best evidence accepting fully that the decisions are being made in the face of relative ignorance. As such, management decisions must incorporate the clinician’s experience and expertise, and weigh heavily the patient’s wishes and desires regarding extraction versus retention after a careful, balanced review of the risks and benefits of both treatment options. The content of this article reflects largely the author’s personal decision-making process based on a careful literature review and clinical experience/expertise. The author admits freely and fully that the quality of the evidence used to support the management of asymptomatic, disease-free M3s is Level 5, namely, expert opinion.
The purpose of this article is to: (1) review the functional definition of impaction used herein, (2) outline a clinical classification system to categorize M3s based on patients’ report of symptoms and the presence of clinical or radiographic disease associated with the M3s, (3) introduce an algorithm for managing M3s, and (4) discuss in some detail the rationale for advocating treatment of asymptomatic, disease-free M3s either with extraction (or other appropriate operative interventions) or retention active surveillance.
Definition of an impacted tooth
For the purposes of this article, the working definition of an erupted tooth is one that is fully visible in the mouth, has reached the occlusal plane, all 5 surfaces are accessible for examination, and has attached gingiva around the tooth. An erupted tooth may be functional, malpositioned in the arch, or nonfunctional. An impacted tooth may or may not be visible. Its presence may only be detectable by periodontal probing or on radiographic images. If visible, it does not meet the definition of an erupted tooth. An impacted tooth is not disease. It is simply an anatomic description suggesting that there is inadequate space to accommodate the tooth in the dental arch. An erupting tooth is visible in the mouth and, based on physical and radiographic examinations, appears to have adequate hard and soft tissue space available to become an erupted tooth. An erupting tooth is a dynamic situation. Its status needs to be reevaluated periodically to determine if the tooth has erupted or has become impacted. In this article, there is no working definition for a partially erupted tooth. A tooth is either erupted, impacted, or erupting. These definitions ( Table 1 ) apply to all teeth, not solely to M3s.
| Symptoms Attributable to M3s | Clinical or radiographic evidence of disease | |
|---|---|---|
| Yes (D+) | No (D−) | |
| Yes (S+) | A | B |
| No (S−) | C | C |
Definition of an impacted tooth
For the purposes of this article, the working definition of an erupted tooth is one that is fully visible in the mouth, has reached the occlusal plane, all 5 surfaces are accessible for examination, and has attached gingiva around the tooth. An erupted tooth may be functional, malpositioned in the arch, or nonfunctional. An impacted tooth may or may not be visible. Its presence may only be detectable by periodontal probing or on radiographic images. If visible, it does not meet the definition of an erupted tooth. An impacted tooth is not disease. It is simply an anatomic description suggesting that there is inadequate space to accommodate the tooth in the dental arch. An erupting tooth is visible in the mouth and, based on physical and radiographic examinations, appears to have adequate hard and soft tissue space available to become an erupted tooth. An erupting tooth is a dynamic situation. Its status needs to be reevaluated periodically to determine if the tooth has erupted or has become impacted. In this article, there is no working definition for a partially erupted tooth. A tooth is either erupted, impacted, or erupting. These definitions ( Table 1 ) apply to all teeth, not solely to M3s.
| Symptoms Attributable to M3s | Clinical or radiographic evidence of disease | |
|---|---|---|
| Yes (D+) | No (D−) | |
| Yes (S+) | A | B |
| No (S−) | C | C |
Classifying M3s to facilitate clinical decision making
M3s can be grouped into 4 clinical categories based on 2 axes, patients’ report of symptoms (present or absent), and clinical or radiographic evidence of disease (present or absent).
During the preoperative visit, clinicians should ask patients about symptoms or concerns that may be related to the M3s. Patients commonly report symptoms of pain, swelling, limitation of motion, bad taste, or smell. Patients also attribute signs of incisor crowding to their impactions. Most data, however, suggest that the crowding is due to insufficient space to accommodate all of the teeth because of a discrepancy between tooth and jaw size, not the result of impacted teeth trying to erupt and “squeeze” into the dental arch by crowding out other teeth.
The clinician then needs to determine if the symptoms are attributable to the M3s. Although usually not a major diagnostic challenge, some patients will mistake masseter muscle pain (myalgia) for M3 pain. Other patients with erupting M3s will report pain symptoms that may be due to the inflammatory side effects of teething. In the setting of adequate space to accommodate the M3s, teething pain is a side effect of development, not an inflammatory disease. In the absence of adequate space to accommodate the M3s, teething pain may be sufficiently severe to warrant intervention.
Patients commonly report no symptoms attributable to the M3s and present for evaluation because “My dentist referred me.” After completing the history and physical and radiographic examinations, the clinician will need to decide that the patients’ symptoms are related to the M3s (symptomatic, abbreviated S+) or that patients have no symptoms or the symptoms are unrelated to the M3s (asymptomatic, abbreviated S−).
Because of the high percentage of asymptomatic disease present in M3s, careful physical and radiographic examinations are indicated. Obvious signs of inflammatory disease such as pericoronitis, caries, or periodontal disease are common. More subtle signs of disease, however, may be present. The following aspects of physical examination are important: (1) eruption status and, if erupted, the position in the arch; (2) functional status of the tooth; and (3) probing status. If the tooth is not visible, probing is important to determine whether the tooth communicates with the oral cavity. If the tooth can be detected on probing, this suggests the tooth is chronically contaminated with oral flora. Probing is also valuable to determine the periodontal health around the M3 and the adjacent second molar (M2). Probing depths (PDs) that are greater than 4 mm are associated with an increased risk of clinically significant (>2 mm) changes in PDs, suggesting a progression of periodontal disease. Specifically, when compared with subjects with PDs less than 4 mm at baseline, those with PDs greater than 4 mm have a nearly 40% increased risk for worsening periodontal health as evidenced by increased PDs after 2 years of follow-up.
After completing the physical examination, the clinician can initially classify the M3 as disease free (abbreviated D−) or disease present (abbreviated D+). A D− M3 can be fully erupted and well positioned in the arch and have PDs of less than 4 mm around the M3, and may be functional. At the other extreme, a D− M3 is not visible in the mouth, cannot be probed, and has PDs of less than 4 mm around the distal aspect of the adjacent M2, and its presence is only confirmed by radiographic imaging.
A radiographic examination is required to confirm the disease status of the M3. Without clinical evidence of M3s, the radiograph will confirm the presence (or absence) of M3. Imaging is also valuable to assess the anatomy of the M3 and its relationship to other local anatomic structures such as the mandibular nerve or adjacent second molar (M2). Although a numerically rare complication of retained M3s, in a tertiary referral practice it is not uncommon to see community patient referrals who are asymptomatic by history and have an unremarkable clinical examination, only to discover on radiographic examination jaw lesions that are several centimeters in diameter ( Fig. 1 ). More commonly, disease radiographically associated with asymptomatic M3s includes inflammatory radiolucent lesions, internal resorption or caries, or caries/resorption of the adjacent M2.
