Migrating third molar: A report of a case

Military Medicine, Oct 2003 by Francis, Paul Olsen, Fowler, Edward Brian, Willard, Craig C

Pathologic migration is an abnormal change in the position of a tooth within the dental arch. There are many etiologic factors associated with this phenomenon, but the exact cause is often difficult to diagnose. The following is a report of a 42-year-old man exhibiting a unique form of bilateral migration of his mandibular third molars. He was asymptomatic and unaware of this occurrence. The morbidity to remove these teeth was deemed too great to justify extraction. Biopsy of the overlying tissue associated with a left-impacted third molar revealed no significant pathologic process other than inflammation and some hyperplasia within the dental follicle. Histologic-radiographie correlation was inconclusive in determining whether epithelium from pericoronal soft tissue involving the right third molar was from a hyperplastic dental follicle or a small dentigerous cyst. It is speculated that the ultimate cause of the migration of the third molars was severe, aggressive periodontal disease of the adjacent molars.

Introduction

Pathologic tooth migration is defined as "The movement of a tooth out of its former position when the etiology or etiologies responsible for such movement are associated with a disease process."1 Carranza2 defined pathologic migration as a tooth displacement that results when the balance among factors that maintain the physiologic position of the tooth are disturbed by periodontal disease. Pathologic migration is often disfiguring. When it affects the anterior dentition, it is often the chief complaint expressed by periodontal patients.3 The prevalence of pathologic migration has been reported as ranging from 30% to 56%.4-7 Etiologic factors of pathologic migration may include periodontal attachment loss, inflammation, occlusal factors, parafunctional habits, frenum pull, iatrogenic dentistry,4 tooth loss, drifting, drug-induced gingival overgrowth, caries, and overhangs.8 Behavioral factors may include bruxism, tongue thrust, lip habits, sucking habits, and frequent use of musical instruments.4

In the developing mandible, space for the third molar is made by forward movement of the erupting dentition and resorption of bone at the back of the dental arch.9 Lack of space for the third molar and subsequent impaction may primarily be a result of inadequate mandibular growth and a backward direction of eruption.10 Third molars can change their angulation despite contact or before contact with second molars.11 Studies in a transverse dimension suggest that the buccolingual position of a third molar may be important in its development. The bone density of the internal oblique ridge, the pterygomandibular raphe, or attachment of the buccinator muscle may influence eruption.12,13

Completely covered and deeply impacted third molars may not necessarily require extraction. Risk of complications, which include paresthesia and damage to second molars, may preclude extraction in asymptomatic cases, particularly after age 25 years.14 Despite morbidity, there is often good reason to extract partially and completely impacted third molars. Gingivitis, caries, cheek biting, difficult access, for hygiene, and recurrent pericoronitis are just some of the complications associated with third molar retention. Orthodontic and prosthetic considerations might necessitate extraction. Additionally, oral pathology, such as cysts and neoplasms, are further reasons for removal.15,16 Chronic destructive periodontitis frequently involves the distal aspect of the second molars. Furthermore, inadequate development and maturation of the attachment apparatus distal to the second molar or destruction of this supporting attachment are complicating risks that may necessitate third molar extraction.14

The following case report illustrates bilateral migration of mandibular third molars. The patient was asymptomatic and unaware of the presence of these teeth. Due to severe periodontal disease, adjacent teeth were extracted and biopsies of the overlying follicles were obtained.

Case Report

A 42-year-old Caucasian man was referred to the periodontal service because of Periodontal Screening and Recording scores of 4 in three sextants. His medical history was significant for having quit smoking approximately 11 years earlier. His dental history included a periodontal evaluation 3 years previously and 1 year previously. His only periodontal treatment during that time period included extraction of maxillary second and third molars plus one session of initial therapy. Basically, he had been noncompliant with periodontal therapy. Clinical examination revealed poor homecare, moderate-to-severe bleeding upon probing, generalized mobility with teeth 3 and 18 being depressible, suppuration around teeth 10, 11, 18, and 31, and isolated areas of recession. However, his gingivae demonstrated an adequate zone of keratinized, attached tissue.

Current radiographs revealed severe bone loss at his molars, maxillary and mandibular anterior teeth, and teeth 11 and 12. Furcations of all molars exhibited radiolucencies. Although teeth 5 and 6 exhibited moderate horizontal bone loss, the other bicuspid regions presented with mild involvement. Previous endodontic therapy at teeth 3 and 9 was considered questionable, but these teeth were asymptomatic.