CE 5 CONTINUING EDUCATION Some Wisdom About the Removal of Wisdom Teeth Daniel M. Laskin, DDS, MS, DSc (Hon)Indications for the removal of impacted third molars include Occasionally, however, the infection can spread beneathpericoronitis, periodontitis, caries, resorption of the second the buccinator muscle and give rise to a buccal spacemolar, cyst formation, and interference with orthodontic abscess or posteriorly into the pterygomandibular space.treatment. While the prophylactic removal of asymptomatic Once there has been an episode of pericoronitis, there isthird molars may still be controversial, there is a general a tendency for the infection to recur intermittently whenagreement that they should be removed when a patho- complete eruption of the tooth is not possible.logic condition is present. This article reviews specificindications for removal of impacted third molars, the argu- Periodontitisments for their prophylactic removal, and the specific Constant food impaction and plaque retention between ainstances when such teeth should not be removed. partially impacted third molar and the adjacent second molar can result in inflammation and considerable loss ofIndications for Removal of Impacted interseptal bone (Figure 1). Such periodontal pocket for-Third Molars mation not only weakens the support of the second molar,Pericoronitis which may loosen, but also apical extension of the infec-Pericoronitis is the most common condition affecting tion that can lead to its devitalization. Once a deep perio-impacted third molars. Bacteria gain access into the fol- dontal pocket develops, removal of the impacted thirdlicular space through an opening in the overlying gingivaor through the gingival crevice distal to the second molar.Such infections may remain localized in the pericoronalregion, spread via the lymphatic system into the sub-mandibular lymph nodes, or extend directly into thesurrounding tissues. The most frequent site of direct exten-sion is the buccal vestibule above the attachment of thebuccinator muscle, which causes a vestibular abscess.Daniel M. Laskin, DDS, MS, DSc (Hon), received a DDS degreefrom Indiana University and a Master of Science degree fromthe University of Illinois. He is Professor and Chairman of theDepartment of Oral and Maxillofacial Surgery, School of Figure 1. Radiograph of an impacted third molarDentistry, and Professor and Chairman of the Division of Oral causing severe periodontal destruction as well as caries involving the second molar. This couldand Maxillofacial Surgery, Department of Surgery, School of have been prevented by earlier removal ofMedicine, Virginia Commonwealth University. the third molar. September/October 2001 15
Wisdom About Wisdom Teeth CE 5 CONTINUING EDUCATION molar will not eliminate it. Therefore, the impacted tooth should be extracted at the first sign of periodontal infec- tion. This will not only arrest the condition, but may also decrease the excessive crevicular depth on the distal aspect of the second molar. 1 Dental Caries Partial eruption of an impacted third molar in the oral envi- A ronment increases its susceptibility to caries due to the accumulation of food debris and the difficulty of keeping the area clean. The restoration of such carious lesions is often impossible due to poor access. Even when the tooth is restored, recurrent caries is a frequent finding. For these reasons, removal of the third molar is indicated, even when the carious lesion does not extend into the pulp. The same factors that make the third molar suscep- tible to caries can also affect the adjacent second molar B (Figure 1). Such lesions should not be restored until the Figure 2A. Impacted third molar causing resorption of the third molar is removed. This not only reduces the possi- distal root of the second molar. 2B. Post-extraction radio- bility of recurrent tooth decay, but also avoids possible graph reveals the extent of the damage. damage to the restoration during the surgical procedure. follicular enlargement. Frequent radiographic evaluation Root Resorption is indicated in those instances when there is possible Pressure from the crown of an impacted third molar against enlargement of the follicle and the tooth has been allowed the root of the second molar may result in pathologic to remain. A cyst can develop and remain asymptomatic resorption (Figure 2A & 2B). When this diagnosis is made, 2 for long periods during which it may grow to a large size care must be exercised not to confuse such areas of root and cause considerable bone destruction. Moreover, resorption with the shadows produced in the radiograph ameloblastomas and even carcinomas arising in the walls by the overlap of the molars due to improper horizontal of dentigerous cysts have been reported.4,5 angulation of the cone of the x-ray machine or the bucco- or linguoversion of the impacted tooth (Figure 3). Idiopathic Pain Removal of only the impacted tooth is indicated if the Occasionally, a patient may complain of facial pain, yet resorptive process has not involved the pulp of the sec- there may be no apparent clinical or radiographic evidence ond molar. If the second molar has been devitalized and of any abnormality other than the presence of a deeply must be extracted, however, it may be advisable to leave embedded, impacted third molar with no obvious oral com- the third molar in young patients. munication. Though there may be no satisfactory expla- nation for why such a tooth can cause pain, some patients Cyst Formation experience relief following its removal. Therefore, it is jus- The third molar is the tooth most often involved in the for- tified to remove impacted third molars in such instances. mation of dentigerous cysts. Eighty percent of the follicles around the crown of the third molar are wider than 2.5 mm Presence in an Edentulous Ridge and have been shown to have an epithelial lining. Such 3 An impacted tooth is occasionally found during a routine teeth should be removed whenever there is indication of radiographic examination in a ridge that appears to be16 The Journal of Practical Hygiene
CE 5CONTINUING EDUCATION Laskin molar should never be allowed to remain when its reten- tion would jeopardize the successful removal of the lesion. Moreover, an impacted third molar should never be left in an area that will be subjected to radiation therapy. The presence of an impacted third molar weakens the mandible and therefore trauma to the jaw is more likely to cause a fracture. Should a mandibular fracture occur in the third molar region, removal of the tooth is often indi- cated as part of the treatment (Figure 4). It may be advis- able to consider removal of impacted teeth prophylactically in persons who engage in contact sports.Figure 3. Impacted third molar in linguoversion appearingto be causing resorption of the second molar. Prophylactic Removal of Impacted Third Molarsedentulous. Unless the tooth is completely covered with Clinical experience has shown that most impacted teethbone and its extraction would cause considerable destruc- will ultimately give rise to some difficulty. For example,tion of the alveolar process, it should be removed. the incidence of pericoronitis has been reported to rangeDetermining the amount of bone over the tooth from a from 27% to 34%, and the incidence of caries to rangeradiograph, however, is not always a simple task. Since from 3% to 15% in patients presenting for removal ofthe radiograph provides merely a two-dimensional view of impacted teeth.6-8the tooth, it may appear to have considerable bone over Several studies have also shown a significant rela-the superior surface when actually it is only partially cov- tionship of periodontitis and periodontal pocket formationered. If allowed to remain, compression of the overlying with impacted third molars.9,10 Moreover, an increase in themucosa between the crown of the tooth and a denture visible plaque and gingival bleeding indices as far forwardmay not only cause considerable pain, but the pressure can as the canine teeth has been demonstrated in patients withcause an ulceration of the mucosal tissue, which can pro- partially erupted third molars, and the plaque index wasduce a pathway for the development of an infection. found to improve after their removal.11-13 With the recent implication of chronic periodontal infection as a possibleOther Indications contributor to cardiovascular disease,14 this may also beIn addition to the aforementioned conditions, impacted an important justification for the prophylactic removal ofthird molars may also be involved in other situations that impacted teeth. Additionally, removal of these teeth at anrequire their removal. These teeth can sometimes interfere early age (before 25 years) has been shown to result in awith the normal path of eruption of the adjacent second significant postoperative reduction in the depth of the infra-molar and should be removed as soon as this situation is bony defects, whereas this does not occur in older patients.15recognized so that the second molar has the best oppor- The National Institute of Dental Research Consensustunity to erupt. Likewise, impacted third molars can inter- Development Conference on Removal of Third Molarsfere with distal orthodontic tooth movement. They can also recommends that such teeth be removed as soon as it isinterfere with the proper performance of orthognathic obvious that there is insufficient space to accommodatesurgery when this involves the third molar region. In such them or that they are not in a position for normal erup-cases, the impacted tooth must be removed at the time of tion to occur.16 This conference concluded that impactionsurgery or, preferably, prior to it. or malposition of a third molar may justify its removal, and Benign and malignant neoplasms of the soft tissues and that such treatment is not considered prophylactic. Growthbone can occur in the third molar region, and the third of the mandible, with the accompanying resorption of the September/October 2001 17
Wisdom About Wisdom Teeth CE 5 CONTINUING EDUCATION Figure 4. Mandibular fracture in the third molar region. Figure 5. Radiograph of an impacted third molar in a patient in whom the second molar is at risk due to a deep restoration. anterior border of the ramus to provide space for the third by a deep maxillary overbite and the natural tendency of molar as well as growth of the maxilla are essentially these teeth to upright with age. completed between 16 and 17 years of age, and therefore the decision regarding prophylactic removal can generally Contraindications be made at about that time. Since the surgical procedure in an adult is generally more Although their potential for causing crowding of the complex,19 it is best to allow deeply embedded, asympto- mandibular incisors is frequently given as a reason for matic impacted third molars that are covered with bone and the prophylactic removal of impacted third molars, and do not communicate with the oral cavity to remain, even this is sometimes seen as these teeth are erupting, the rela- though there is a possibility that pathologic involvement tionship between these two events remains unproven.17,18 may subsequently occur. If one is dealing with serious If an anterior force was caused by the erupting third pathology, it is generally possible to adopt a temporiz- molars, it would require a corresponding forward shift of ing approach in a patient who is a poor surgical risk. all of the posterior teeth in order for it to be transmitted Pericoronal and/or periodontal infections can be treated to the incisors, and this does not occur. Moreover, under with irrigation and antibiotics, caries can be excavated and such circumstances, the disruption of tooth contact would a restoration placed, a pulp can be devitalized, a cyst can be expected to occur in the canine and not the incisor be marsupialized and, if necessary, a second molar can be region. An alternative explanation for the development of extracted to create space in the dental arch. It should be anterior tooth crowding may be the increased plasticity of emphasized, however, that such procedures are compro- the alveolar bone and periodontal ligaments that accom- mises and not the usual treatments of choice. panies the hormonal changes in adolescence, which causes An impacted third molar should not be removed when an imbalance between the forces ordinarily contributing to there is some question about the future status of the tooth stability.18 Supporting this concept is the fact that second molar (eg, deep caries, large restoration, endodon- incisor crowding is also evident in persons with missing tic treatment, or extensive periodontal disease) (Figure 5). third molars and in those who have had them removed In such cases, it is assumed that if the second molar is prior to orthodontic treatment. 16,17 In the latter instance, the extracted at a subsequent time, the third molar will either crowding may represent the relapse of teeth orthodonti- erupt into a more functional position or can at least serve cally placed in a physiologically untenable position. Other as a bridge abutment. The position of the impacted tooth possible factors contributing to crowding of the lower and the age of the patient are important considerations incisors are a restriction of forward mandibular growth in making this assumption.18 The Journal of Practical Hygiene
CE 5CONTINUING EDUCATION SPONSORED BYConclusionImpacted third molars are subject to a variety of pathologicprocesses, some of which may result in serious irreversibleconditions. Therefore, it is important to carefully examinethese teeth at every dental visit. The dental hygienist playsan important role in this process. When such teeth are pre- Lookingsent, the advantages and disadvantages of prophylactic for Justremoval need to be discussed with the patient so that Phenomenalan informed decision about their retention or removal can Hygienists!be made.References 1. Szmyd L, Hester WR. Crevicular depth of the second molar in impacted third molar surgery. J Oral Surg 1963;21:185-189. 2. Nitzan D, Keren T, Marmary Y. Does an impacted tooth cause root resorption of the adjacent one? Oral Surg Oral Med Oral Pathol 1981;51(3):221-224. 3. Conklin WW, Stafne EC. A study of odontogenic epithelium in the dental follicle. J Amer Dent Assoc 1949;39:143-148. 4. Shteyer A, Lustmann J, Lewin-Epstein J. The mural ameloblastoma: A review of the literature. J Oral Surg 1978;36(11):866-872. 5. Maxymiw WG, Rood RE. Carcinoma arising in a dentigerous cyst: A case report and review of the literature. J Oral Maxillofac Surg 1991; 6. 49(6):639-643. Nordenram A, Hultin M, Kjellman O, Ramstrom G. Indications for Ultradent Products and JPH— surgical removal of the mandibular third molar: Study of 2,630 cases. Swed Dent J 1987;11(1-2):23-29. Celebrating 7. Lysell L, Rohlin M. A study of indications used for removal of the mandibular third molar. Int J Oral Maxillofac Surg 1988;17(3):161-164. EXTRAORDINARY HYGIENISTS 8. Stanley HR, Alatter M, Collett WK, et al. Pathological sequelae of “neglected” impacted third molars. J Oral Pathol 1988;17(3):113-117. 9. Ash MM Jr, Costich ER, Hayward JR. A study of periodontal hazards The Journal of Practical Hygiene (JPH) is pleased to partner with of third molars. J Periodontal 1962;33:209-219. Ultradent Products, Inc. to sponsor the “Just Phenomenal10. von Wowern N, Nielsen HO. The fate of impacted lower third molars Hygienist” Program featured in past issues of JPH. after the age of 20. A four-year clinical follow-up. Int J Oral Maxillofac Surg 1989;18(5):277-280. Ultradent recognizes the importance of quality service for the den-11. Ylipaavalniemi P, Turtola L, Rytomaa I, et al. Effect of position of wisdom teeth on the visible plaque index and gingival bleeding index. tal profession and would like to acknowledge those hygienists who Proc Finn Dent Soc 1982;78(1):47-49. take pride in their professional role, give 110% to their patients and12. Giglio JA, Gunsolley JC, Laskin DM, Short KJ. Effect of removing third coworkers, and make everyone’s day a little brighter. molars on plaque and gingival indices. J Oral Maxillofac Surg 1994; 52(6):584-587. If you would like to nominate such an individual, please provide a13. Grondahl HG, Lekholm U. Influence of mandibular third molars on related supporting tissues. Int J Oral Surg 1973;2(4):137-142. short essay describing why this person is a “Just Phenomenal14. Beck JD, Pankow J, Tyroler HA, Offenbacher S. Dental infections Hygienist.” One winner will be chosen and featured within and atherosclerosis. Am Heart J 1999;138:528-533. each edition of JPH. One grand prize winner will be selected from15. Kugelberg CF, Ahlstrom U, Ericson S, Hugoson A. Periodontal heal- ing after impacted lower third molar surgery. A retrospective study. these winners for a FREE trip to the 2002 ADHA in Beverly Hills, Int J Oral Surg 1985;14(1):29-40. California—compliments of Ultradent.16. NIH consensus development conference on removal for third molars. J Oral Surg 1980;38(3):235-236. Please include a photograph of the entire dental team as well as an17. Bjork A, Skieller V. Normal and abnormal growth of the mandible. A individual photograph of the “Just Phenomenal Hygienist.” synthesis of longitudinal cephalometric implant studies over a period of 25 years. Eur J Orthodont 1983;5(1):1-46. Mail nominations to:18. Ades AG, Joondeph DR, Little RM, Chapko MK. A long-term study of the relationship of third molars to changes in the mandibular dental The Journal of Practical Hygiene arch. Am J Orthodont Dentofac Orthop 1990;97(4):323-335. Just Phenomenal Hygienist Program19. Osborn TP, Frederickson G, Small IA, Torgeson TS. A prospective study of complications related to mandibular third molar surgery. Montage Media Corporation J Oral Maxillofac Surg 1985;43(10):767-769. 1000 Wyckoff Avenue Mahwah, NJ 07430 SEND YOUR NOMINATIONS TODAY!
CONTINUING EDUCATION (CE) EXERCISE NO. 5 CE 5 CONTINUING EDUCATION To submit your CE Exercise answers, please use the answer sheet found within the CE Editorial Section of this issue and complete it as follows: 1) Identify the Article; 2) Place an X in the appropriate box for each question; 3) Clip the answer sheet from the page and mail it to the CE Department at Montage Media Corporation. For further instructions, please refer to the CE Editorial Section. Answers to the 10 multiple-choice questions for this CE exercise are based on the article “Some Wisdom About the Removal of Wisdom Teeth” by Daniel M. Laskin, DDS, MS, DSc (Hon). WARNING: The Journal of Practical Hygiene encourages its readers to pursue further education when necessary before implementing any new procedures expressed in this article. Reading an article in The Journal of Practical Hygiene does not fully qualify you to incorporate these new techniques or procedures into your practice. Learning Outcomes: • Review specific indications for removal of impacted third molars. • Understand the arguments for their prophylactic removal. • Identify specific instances when such teeth should not be removed. 1. A partially impacted mandibular third molar 6. Which of the following statements regarding can cause loss of the interseptal bone between radiographs of impacted third molars is false: it and the second molar due to: A. There may be only partial bony coverage of the A. Pressure on the bone. superior surface even when there appears to be B. Movement of the second molar. full coverage. C. A failure to support the bone. B. Radiographs are helpful in determining the amount D. Constant food impaction. of bone over the tooth. C. Radiographs are not helpful in determining whether 2. Which of the following occurs following there is buccal or lingual bone over the crown. removal of an impacted third molar? D. A radiograph may show bone over the crown A. It can result in regeneration of the interseptal bone even when no bone is present. distal to the second molar. B. It can result in decreased crevicular depth distal to 7. Which of the following is usually not a contraindi- the second molar. cation to the removal of impacted third molars: C. It can prevent further periodontal disease distal to A. A deeply embedded, asymptomatic third molar in the second molar. an adult. D. All of the above. B. The poor systemic condition of the patient. C. The potential risk of having to extract the second 3. Restoration of carious lesions in third molars is molar at a future time. seldom done because of: D. The lack of radiographic pathosis in a patient with A. The difficult access to the lesion. chronic facial pain. B. The cost of such restorations. C. The close proximity of the dental pulp in such teeth. 8. Which of the following is not a reason for removing D. The weakness of the enamel makes restoration impacted third molars in orthodontic patients? difficult. A. They can interfere with orthodontic tooth movement. 4. A follicular space around the crown of an B. They can interfere with orthognathic surgery. C. They can cause crowding of the lower incisors. unerupted third molar greater than 2.5 mm D. They can impede eruptions of the second molar. wide is generally considered to be: A. Within the range of normality. 9. The most common pathologic condition involving B. A dentigerous cyst. impacted third molars is: C. An early ameloblastoma. A. Dental caries. D. An eruption cyst. B. Periodontitis. 5. With regard to periodontitis and periodontal C. Pericoronitis. D. Cyst formation. pocket formation, removal of impacted mandibular third molars causes decreased: 10. The most frequent site for the spread of a A. Gingivitis in the maxillary teeth. periocoronal infection is the: B. Plaque and bleeding indices in the anterior teeth. A. Submandibular space. C. Periodontal pocket formation in the molar and B. Buccal vestibule. premolar teeth. C. Pterygomandibular space. D. Plaque and bleeding indices in the posterior teeth. D. Buccal space.20 The Journal of Practical Hygiene