Gemination of mandibular third molar – A rare case with use
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Tooth development is a complex process that occurs under the effect of numerous genetic and environmental factors. As a result of alterations in these factors, numerous alterations of teeth can occur. Of these, variations in the number of teeth are the commonest anomaly seen.

The developmental disturbances in the shape of the teeth include gemination, fusion, concrescence, dilaceration, talon cusp, dens in dente, dens evaginatus, taurodontism, and supernumerary roots.

A 23-year-old female patient reported with the chief complaint of pain in the left lower back tooth region for the past 10 days. Clinical examination revealed partially erupted 38 with redness and swelling of pericoronal flap. In light of history and clinical picture, a provisional diagnosis of pericoronitis i.r.t partially erupted 38 was made and radiographic examination was advised.

Orthopantomogram (OPG) showed a mesioangular impacted 38 and a radio-opaque distinct crown-like structure attached to the distal surface of 38 root. Enamel and dentin-like structures were appreciated in the distal crown-like structure. A well-defined homogenous radiolucency distal to 38 and anomalous crown-like structure suggestive of pericoronal bone loss was noted.

Based on the radiographic findings, a differential diagnosis of gemination in relation to 38, a fusion of 38 with a distomolar/supernumerary tooth and presence of compound odontoma were considered. A supernumerary tooth commonly shows aberrant; conical or tuberculated form. Thus, for the elucidation of anatomy and confirmation diagnosis, CBCT imaging was advised.

CBCT scan of the left posterior mandible region was taken with a 3D digital imaging system with 80 kVp tube voltage and 10 mA tube current. CBCT images of 38 regions revealed two crown-like structures: mesial (crown/tooth I) and distal (crown/ tooth II); with the distal crown angulated buccally within the anterior border of left ramus and showed close approximation to the inferior alveolar canal. The mesial crown (crown I) revealed typical molar anatomy showing 5 cusps—mesiobuccal, distobuccal, distal, mesiolingual, and distolingual. The distal crown (crown II) also showed 5 cusps showing comparable morphology .

Homogeneously hypodense pericoronal area of bone loss was noted i.r.t crown II with loss of crestal bone. Discrete coronal pulp chambers were seen with respective crowns. The complex root anatomy encountered was interpreted by a series of multiplanar images which revealed that radicular region of tooth I bifurcates to form buccal and lingual roots. The buccal root housing the mesiobuccal root canal and the lingual root accommodating mesiolingual and distal root canals was noted. At the point of bifurcation, the distal root canal (lingual root) fuses with the tooth II pulp chamber and continues now as a single broad lingual root and root canals in I–II configuration. Both roots showed about 2–2.5 mm distance from the inferior alveolar canal .Based on the above evidence, the radiographic diagnosis of the gemination of the third molar was concluded.

Following this, necessary blood investigations were done and surgical extraction of 38 was planned. Careful surgical removal of the tooth was carried out under local anesthesia . The teeth were spliced for convenient extraction with minimal trauma . Two separate molar crowns with common roots were identified indicating an incomplete division of single tooth germ. A definitive diagnosis of gemination 38 was given. Post-extraction sutures were placed, medications prescribed, and the patient was followed up for postoperative healing, which was uneventful.
In this case, the offending tooth was a third molar causing pericoronal infection, so extraction was chosen over conservation for the best patient interest.

Source : http://www.jiaomr.in/article.asp?issn=0972-1363;year=2019;volume=31;issue=4;spage=377;epage=381;aulast=Bhatt
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