The surgical removal of impacted third molars is the most common procedure performed by maxillofacial surgeons, but ectopic placement is quite rare. Only a few cases of ectopic third molars in sigmoid notch have been reported. We present a clinical case of a third ectopic molar located in sigmoid notch and associated with a dentigerous cyst in a 32-year-old patient, which was extracted through intraoral approach. The aetiology of ectopic mandibular third molars has not yet been completely clarified. Treatment should be carefully planned according to the position of the ectopic tooth and the potential for trauma caused by the surgery.
Keywords: Ectopic third molar; Intraoral approach; Sigmoid notch
Inclusion of the third molar is a common condition with a frequency of 20-30%. Ectopic mandibular third molars, however are unusual, with their heterotrophic positions reported in the mandibular ramus, in the coronoid process and in the condylar or the sub condylar region [1,2]. Ectopic third molar are those that are impacted in unusual positions, or that have been displaced and are at a distance from their normal anatomic location. Tooth development results from a complicated multi-step interaction between the oral epithelium and the underlying mesenchymal
tissue. Ectopic eruption can be associated with developmental disturbances, pathologic processes or iatrogenic activity. Only
seven cases of ectopic mandibular third molars in sigmoid notch reported in the literature over the past 40 years [3-9]. Other locations for ectopic third molar are the maxillary sinus and the infratemporal fossa. In these cases, the removal of the ectopic third molar can be difficult, and procedure requires surgical intervention. The aetiology and protocol for extraction are still unclear .
In this report we present a clinical case of a third ectopic molar located in sigmoid notch and associated with a dentigerous cyst in a 32-year-old patient, which was extracted through intraoral approach and review the literature reports over the past 40 years.
A 31-year-old healthy and asymptomatic Caucasian man was
referred to the department of Oral and Maxillofacial Surgery by
his Dentist. He reported several episodes of left preauricular pain
and swelling of the parotid region that remitted with antibiotic
and anti-inflammatory treatment. The patients also experimented
limitation of mouth opening. The intraoral examination revealed
bulging of the inferior left vestibule that was tender to palpation.
Panoramic radiography showed an inverted ectopic third molar
in the left sigmoid notch region with an associated cyst (Figure
1). The ectopic third molar was situated with the apex facing
the sigmoid notch and the crown facing downward. A small well
defined radiolucent area encompassing the crown of the ectopic
third molar was observed. A Computed Tomography (CT) scan
confirmed these findings.
Under naso-tracheal general anaesthesia, an intraoral access
was obtained via an incision on the anterior edge of the mandibular
ramus and along the external oblique ridge down to the ectopic
third molar. After periosteal dissection of the ascending ramus of
the mandible, a window in the external cortical bone was created
using a 3mm carbide round bur on a straight surgical hand piece
and the crown of the ectopic third molar was exposed. A bony
window just larger that the crown was created and the tooth was
then elevated out of the bony socket by an elevator after odonto
section of the ectopic third molar (Figure 2). The associated cyst
was removed later and the wound was sutured after irrigation
with saline solution.
The patient had a satisfactory postoperative recovery.
Amoxicillin, 1000mg three times a day was given for a week and
Ibuprofen, 600mg three times a day for three days. Mouth opening
improved progressively and the function of the inferior alveolar
nerve was completely normal one month after surgery (Figure 3).
The diagnosis of dentigerous cyst was confirmed by histological
The Etiology of ectopic third molars has not yet been completely
clarified. Tooth development results from an interaction between
the oral epithelium and the underlying mesenchymal tissue.
Abnormal tissue interactions during development may potentially
result in ectopic tooth development and eruption. Many theories
have been put forward including, aberrant eruption, trauma,
infection, cyst, tumours and developmental disturbances. In
many cases the aetiology cannot be identified. A mandibular third
molar may be displaced by a lesion such as a cyst or a tumour. The
expansion of a cyst as it develops may result in pressure on the
crown of a tooth and displace it in a direction opposite to the path
of eruption. The dentigerous cyst is a common lesion [5,8,11]. It is
the second most common odontogenic cyst following the radicular
cyst and it is more common in males occurring in the second or
third decade of life. The radiological image is characterized
by a well circumscribed, unilocular and normally symmetric
radiolucent image around the crown of an impacted tooth. It is
usually found in the region of the third molar, and they are more
commonly an isolated finding.
Ectopic eruption of a tooth into a region other than the oral
cavity is rare although there have been reports of tooth in the
nasal septum, mandibular condyle, maxillary antrum, palate and
coronoid process. From 1965 to 2008, only seven reports were
made of ectopic third molar in sigmoid notch. Patients are mostly
asymptomatic [4,7] and the clinical symptoms caused by these
lesions do not differ much from those of other ectopic inclusions
or maxillary cysts [5,8,9]. The most common signs and symptoms
associated with ectopic third molar in sigmoid notch are:
1. Pain and swelling on the ipsilateral side of the mandible
or the preauricular region
2. Limitation of mouth opening, and difficulty in
mastication. Granite et al.  reported a case of impacted
third molar in the sigmoid notch without clinical symptoms
The diagnosis of this condition can easily be made
radiologically with radiological studies (orthopantomogram) and
CT scans taken in axial and coronal sections, for confirmation.
The precise location of the ectopic third molar, sometimes with
high-resolution CT scans, may provide direction in choosing the
appropriate surgical method .
The usual treatment for a dentigerous cyst associated
with an impacted third molar is its enucleation together with
the extraction of the tooth. The treatments should be carefully
planned according to the location of the ectopic third molar and
the possible trauma caused in the surgery. This situation makes
it much more difficult to extract the third molar and associated
cyst. Treatment of ectopic third molar in the sigmoid notch is
recommended to avoid the morbidity caused by the infection of
the cyst, risk of fracture, and temporomandibular joint syndrome.
In the cases of ectopic third molar in other locations described in
the literature several approaches have been used, such as intraoral
, retromandibular, preauricular and endoscopic. Whenever
possible intraoral approaches should be used but logically this
will be determined by the location of the ectopic third molar.
The use of endoscopic approach has considerable advantages
[11,14], but requires basic endoscopic equipment and special
training, and this technique may not be indicated in all locations
of an ectopic third molar. If conservative treatment is opted for, a
follow-up of the patient will be necessary. The indication for the
extraction of an ectopic third molar is in general determined by
the presence of symptomatology, or it may be aimed at preventing
future complications. In these cases, the removal of the ectopic
third molar can be difficult, and procedure requires surgical
intervention. The aetiology and protocol for extraction are still