Comprehensive analysis of ectopic mandibular third molar: a rare clinical entity revisited

Abstract

BackgroundEctopic mandibular third molar is a rare clinical entity with incompletely known etiology. Here, we sought to delineate its epidemiological, clinical and radiographic characteristics, and therapy by integrating and analyzing the cases treated in our institution together with previously reported cases.MethodA new definition and classification for ectopic mandibular third molar was proposed based on its anatomic location on panoramic images. Thirty-eight ectopic mandibular third molars in 37 patients and 51 teeth in 49 patients were identified in our disease registry and from literature (1990–2016), respectively. These cases were further categorized and compared according to our classification protocol. The demographic, clinicopathological and radiographic data were collected and analyzed.ResultsThese ectopic teeth were categorized into four levels, 33 in level I(upper ramus), 32 in level II (middle ramus), 15 in level III (mandibular angle) and 9 in level IV (mandibular body). The common clinical presentations included pain, swelling and limited mouth opening, although sometimes asymptomatic. Most teeth were associated with pathological lesions. Treatments included clinical monitor and surgical removal by intra- or extraoral approach with favorable outcomes. Clinical presentations and treatment options for these teeth were significantly associated with their ectopic locations as we classified.ConclusionsEctopic mandibular third molars are usually found in patients with middle ages and in upper and middle ramus of mandible. Surgery is preferred to remove these ectopic teeth and associated pathologies when possible.

Extraoral surgical removal of an ectopic impacted third molar of the mandible. Report of a case

“…Several theories have been proposed such as alterations during odontogenesis and trauma to a developing tooth germ, pathologic and iatrogenic conditions or even crowding ( 1 - 6 ). More specific, a mandibular third molar may be dislocated at a greater distance from its habitual site due to aborted eruption, pathologic causes such as the development of cysts or intraosseous tumors, or due to alteration of its eruption in the presence of odontogenic tumors ( 1 - 6 ). In some cases, dentigerous cysts initially might have been occupying a large part of the ramus forcing and directing the molar in an altered position and then they might have been perforated and subsided ( 2 ).…”

“…A tooth is considered as “ectopic” when it is located in an unusual site, distant from its natural anatomical position ( 1 ). Even though ectopic eruption limited within the dentoalveolar structures is not rare, the dislocation of a tooth in distant sites is infrequent ( 2 , 3 ).…”

“…Even though ectopic eruption limited within the dentoalveolar structures is not rare, the dislocation of a tooth in distant sites is infrequent ( 2 , 3 ). Impaction of third molars is found in 20-30% of the general population, with a predilection for women, however only a few cases of ectopic impacted third molars have been reported in the literature so far ( 1 , 4 ).…”

“…Trauma in the region of eruption and ectopic formation of tooth germs has also been proposed as a possible mechanism ( 4 ). Additionally, contiguity with cystic or neoplastic lesions may lead to an altered location of the tooth ( 1 - 3 , 5 ).…”

“…Usually ectopic third molars are randomly found in panoramic radiographs during routine clinical examinations, as they remain asymptomatic for years ( 1 , 7 ). In some cases they may cause severe episodes of pain, swelling or trismus leading the patient to the clinician, where the diagnosis of an ectopic molar is placed in combination with a cystic or neoplastic lesion ( 8 , 9 ).…”