Cysts associated with longstanding impacted third molars

Copyright©Munksgaard 1993

Int. Z Oral MaxilloJac. Surg 1993, 22:110-112 Printed in Denmark. All rights reserved

tnternationalJoumal of

OraI 8c Max_il]ofacialSurgery ISSN 0901-5027

Pathology

Cysts associated with 10ngstanding impacted third molars

S, C. Girod 1, K.-L. Gerlach 1, G. Krueger 2 1Department of Oral and Maxillofacial Surgery and 2Institute of Pathology, University of Cologne, Joseph-Stelzmann-Str. 9, 5000 K61n 41, Germany

S. C. Girod, K.-L. Gerlach, G. Krueger. Cysts associated with long-standing impacted third molars. Int. J. Oral Maxillofac. Surg 1993," 22." 110-112. © Munksgaard, 1993 Abstract. Three patients are described in w h o m large cysts developed around third molars that had purposely been left in place. The cases presented emphasize the need for an adequate prospective study to evaluate the long-term morbidity of asymptomatic third molars that are left in place. Zusammenfassung. Bei drei Patienten entwickelten sich im Laufe mehrerer Jahre groBe Zysten ausgehend von retinierten Weisheitsz/ihnen, deren Entfernung die Patienten abgelehnt hatten. Die vorgestellten F/ille belegen die Notwendigkeit der Durchf/ihrung einer prospektiven Studie zur K1/irung der Frage von Langzeitfolgen bei retinierten Molaren, die im Kiefer belassen werden.

The surgical removal of impacted third molars is the most c o m m o n l y performed procedure in oral and maxillofacial surgery. It accounts for 50% o f the cost of oral and maxillofacial surgery in the U S A 4. In 1979, the N I H Consensus Development Conference agreed on a number of indications for removal o f impacted third molars, including infection, nonrestorable carious lesions, cysts, tumors, and destruction of adjacent teeth and bone s . Analysis o f retrospective studies reveals that in onethird of the reported cases asymptomatic, "nonfunctional", impacted third molars were removed, presumably as a preventive measure 5'9'1°. The risks and benefits of the removal o f such teeth have recently been discussed and reviewed in the literature, but controversy still exists 4'7. Some authors found that impacted third molars did not cause any problems over a period o f several years in edentulous patients 6. STEPHENSet al. 13 mention that especially the development of dentigerous cysts has been overemphasized. The present paper describes three patients in w h o m large cysts developed

over a 2-13-year period, displacing the third molars involved. The implications for the patients are discussed.

Case reports Patient 1 A 50-year-old man first came to our clinic in 1979. At that time, the impacted third molar of the left mandible was removed because of pericoronitis. Removal of the impacted third molar on the right side was recommended, but the patient refused treatment. In 1992, 13 years later, the patient presented again with a painless swelling in the right mandible. A radiograph showed a large, well-defined osteolytic lesion and displacement of the third molar to the lower border of the mandible. The second and first molars showed root resorptions (Fig. 1). A biopsy showed features consistent with the diagnosis of a dentigerous cyst. The patient underwent a cystectomy with removal of the first, second, and third molars. He was hospitalized for 17 days. A bone graft was used to fill the defect, and the patient also had intermaxillary fixation for 3 weeks.

Patient 2 A 56-year-old man was first seen in 1974 for treatment by a dentist. The radiograph taken

Key words: impacted third molar; cyst. Accepted for publication 10 January 1993

at that time showed an impacted third molar in the left mandible. In 1984, 10 years later, the patient presented with a painless swelling of the left mandible. The radiograph showed displacement of the impacted third molar and a well-defined unilocular radiolucency (Fig. 2). A tentative diagnosis of a dentigerous cyst was made, and the patient underwent surgical removal of the cyst and the impacted third molar. The diagnosis was confirmed by histologic examination.

Patient 3 A 22-year-old woman presented in 1981 with an impacted third molar in the right mandible. An ill-defined radiolucency could already be seen around the impacted tooth. The patient, however, refused surgery at that time. Two years later, radiographs showed a large, well-defined radiolucency and displacement of the impacted third molar (Fig. 3). Because of the magnitude of the lesion, a marsupialization was performed first and cystectomy was performed several months later. The patient was hospitalized for 9 days. She was also advised to come to the clinic at weekly intervals, but, unfortunately, she was lost to follow-up. Initially, the cyst was diagnosed as a dentigerous cyst, but reevaluation of the slides led to the diagnosis of keratocyst.

Cysts with impacted molars

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Discussion

Fig. 1. Panoramic radiograph showing situation at first presentation (top) and 13 years later (below). Note root resorption of first and second molars and displacement of third molar along with large cystic lesion.

Fig. 2. Panoramic radiograph showing situation at first presentation (top) and 10 years later (below). Note unilocular cyst around crown of displaced third molar.

Well-defined guidelines have been established for the removal of pathologically symptomatic impacted third molars s. At present, however, in a large percentage of cases, asymptomatic third molars are removed for various reasons, including prevention of crowding of the dentition, resorption of adjacent teeth, and development of pathologic conditions such as infection, cysts and tumors. Three cases have been described in which asymptomatic, impacted third molars were left in place, but within a 2-13-year period, large cysts developed. The surgical treatment of these large cysts is often associated with considerable morbidity. The risk of permanent damage to the mandibular nerve is increased, and sometimes bone grafts or immobilization of the mandible for several weeks is necessary. The incidence of the development of large cysts and tumors around third molars differs greatly in various studies. BRUCE et al. 1 reported an incidence of 6.2% of cysts and tumors developing around impacted third molars. The incidence was notably highest (13.3%) in the oldest age group (mean age 46.5 years) and lowest (1.5%) in the youngest age group (mean age 20 years). Two of the patients presented belonged to the older age group. In the cases described, it took 2-13 years for these large cysts to develop. In a prospective study, NORDENHAM et al. 9 reported that in 4.5% of the cases suspected cysts were the indication for the removal of an impacted molar. OSBORN et al. reported that, in their study, cysts and tumors were in 0.3% of cases the reason for mandibular third molar surgery 1°. In radiographic studies, DACHI et al. 2 found widening of the pericoronal space larger than 2 mm in 3% of the third molars investigated. ELIASSON et al. 3 found in 3.9% of their third molar group a widening of the pericoronal space of more than 2.5 mm. It was noted in both studies that widened pericoronal spaces are three to eight times more often associated with third molars in the mandible. In neither of those studies was the diagnosis of cyst reconfirmed by histologic examination. The diagnosis was presumably due to arbitrarily defined radiographic findings in all cases. The only study where the diagnosis of a dentigerous cyst was confirmed by histologic examination of the removed tissue is the epidemiologic

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Girod et al. surgery. J Am Dent Assoc 1980: 101: 240 5. 2. DACHISF, HOWELLFV.. A survey of 3874 routine full-mouth radiographs; a study of impacted teeth. Oral Surg 1961: 14: 1165-9. 3. ELIASSON S, HEIMDAHLA, NORDENRAM A. Pathological changes related to longterm impaction of third molars. A radiographic study. Int J Oral Maxillofac Surg 1989: 18: 210-11. 4. FRIEDMAN JW. Containing the costs of third-molar extractions: a dilemma for health insurance. Public Health Rep 1983: 98: 376-84. 5. GOLDBERGMH, NEMARICHAN, MARCO WP. The impacted third molar: referral patterns, patient compliance and surgical requirements. J Am Dent Assoc 1983: 107: 43941. 6. HUANGH, MERCIERP. Asymptomatic impacted teeth in edentulous jaws undergoing preprosthetic surgery. Int J Oral Maxillofac Surgery 1992: 21: 147-9. 7. MERCIERP, PRECIOUSD. Risks and benefits of removal of impacted third molars. Int J Oral Maxillofac Surg 1992: 21: 17-27.

Fig. 3. Panoramic radiograph showing situation at first presentation (top). A vague, undefined radiolucency is already visible around right third molar. Two years later a giant keratocyst had developed, hollowing out almost the entire ascending ramus (below).

study of SHEAR t~ SINGtt 12. They found an annual mean incidence rate for dentigerous cysts of 8.95 per million a m o n g whites in South Africa. It can be concluded from the above studies that the incidence of dentigerous cysts developing around third molars is relatively low 4. Yet, no guidelines have been established to predict, in an individual case, whether cyst development is likely. A recent study showed that pericoronal changes in third molars seem to be unpredictable and that guidelines cannot easily be established 11. This notion is confirmed by two of the cases presented (Figs. 1 and 2). The asymptomatic third molars were left in place at the time of first examination. Both patients developed large dentigerous cysts, and the third molars were severely displaced. The development of the cysts took 10 and 13 years, respectively, in these cases. In the third patient, a third molar of the right m a n dible was left in place that already

showed an ill-defined pericoronal radiolucency (Fig. 3). This keratocyst, as it was later diagnosed, grew rapidly within 2 years and also caused severe displacement of the third molar. The cases presented illustrate the need for further research to calculate the risks when asymtomatic third molars are left in place. Inevitably, these studies have to be conducted over a long time. It appears that even in middleaged patients relatively large cysts m a y develop. With increased age the m o r bidity associated with infection, general anesthesia, and surgery is likely to increase. These factors need to be considered when patients are advised about the advantages and disadvantages of third molar removal. References 1. BRUCE RA, FREDERICKSONGC, SMALL GS. Age of patients and morbidity associated with mandibular third molar

8. NIH Consensus Development Conference on Removal of Third Molars. J Oral Surg 1980: 38: 235-6. 9. NORDENRAM A, HULTIN M, KJELLMAN O, RAMSTROMG. Indications for surgical removal of the mandibular third molar. Swed Dent J 1987: 11: 23-9. 10. OSBORNTP, FREDERICKSONG, SMALLIA, TORGERSON S. A prospective study of complications related to third molar surgery. J Oral Maxillofac Surg 1985: 43: 767-8. 11. SEWERIN I, VON WOWERN N. A radiographic four-year follow-up study of asymptomafic mandibular third molars in young adults. Int Dent J 1990: 40: 24~30. 12. SrmARM, SINGHS. Age-standardized incidence rates of ameloblastoma and dentigerous cysts on the Witwatersrand, South Africa. Community Dent Oral Epidemiol 1987: 6: 195-9. 13. STEPHENSRG, KOGON SL, REID JA. The unerupted or impacted third molar a critical appraisal of its pathological potential. J Can Dent Assoc 1989: 55: 201 7. Address: Dr Dr Sabine C, Girod Department of Oral and Maxillofacial Surgery University of Cologne Joseph-Stelzmann-Str. 9 5000 Kgln 41 Germany