|Year : 2015 | Volume
| Issue : 2 | Page : 241-244
Mandibular third molar gemination: A rare anomaly
Harsha Vardhan Talla1, Shailendar Reddy Adamala1, Sudhir Surapaneni2, Deepa Chillakuru3
1 Department of Oral Medicine and Radiology, Meghna Institute of Dental Sciences, Nizamabad, Telangana, India
2 Department of Oral and Maxillofacial Surgery, Gandhi Dental College, Bhubaneswar, Odisha, India
3 Department of Oral and Maxillofacial Pathology, Narayana Dental College and Hospital, Nellore, Andhra Pradesh, India
|Date of Submission||17-Dec-2014|
|Date of Acceptance||14-Oct-2015|
|Date of Web Publication||21-Nov-2015|
Harsha Vardhan Talla
H. No: 1-2-133, 3rd lane, JKC Nagar, Guntur - 522 006, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Gemination and fusion are anomalies which have close similarity. These anomalies may develop during tooth bud morphodifferentiation as a result of a developmental aberration of the ectoderm and mesoderm. The incidence of these anomalies was reported to be less than 1%, occurring predominantly in incisors and canines with equal distribution in the maxilla and mandible. Gemination and fusion are generally asymptomatic and do not require treatment. However, there could be poor aesthetics, periodontal destruction, or caries leading to pulp necrosis. This article reports a rare occurrence of fusion/gemination in the third molar region.
Keywords: Ectoderm, fusion, gemination, mesoderm
|How to cite this article:|
Talla HV, Adamala SR, Surapaneni S, Chillakuru D. Mandibular third molar gemination: A rare anomaly. J Indian Acad Oral Med Radiol 2015;27:241-4
|How to cite this URL:|
Talla HV, Adamala SR, Surapaneni S, Chillakuru D. Mandibular third molar gemination: A rare anomaly. J Indian Acad Oral Med Radiol [serial online] 2015 [cited 2019 Oct 17];27:241-4. Available from: http://www.jiaomr.in/text.asp?2015/27/2/241/170145
| Introduction|| |
Morpho-anatomical undulations in teeth can be grouped according to the site of occurrence, i.e. crown, root, and root canal of the tooth.  Gemination and fusion are anomalies which have close similarity. These anomalies may develop during tooth bud morphodifferentiation as a result of a developmental aberration of the ectoderm and mesoderm.  Severity of this anomaly depends on the stage of development of the tooth involved. The incidence of these anomalies was reported to be less than 1%,  occurring predominantly in incisors and canines with equal distribution in the maxilla and mandible. These anomalies are more common in deciduous teeth and very rare in permanent molars. ,
According to the stage of tooth development, different degrees of union of cementum, dentin, and enamel are possible. Gemination is an attempt of the tooth bud to divide. This partial division is arrested before tooth development is completed.  The end result is a single tooth with a bifid crown, and the total number of teeth is normal. Fusion is a condition in which two separate tooth buds join together to form a large crown. When counted, the number of teeth is reduced by one. Four types of these anomalous teeth have been reported: 
The etiology of fusion and gemination remains unclear. Grover and Lorton (1985)  claim that local metabolic interference, which occurs during morphodifferentiation of the tooth germ, may be the cause. They suggest that there could be a relationship among gemination, twinning, and odontoma. Another possibility is trauma.  Gemination and fusion are generally asymptomatic and do not require treatment. However, there could be poor aesthetics, periodontal destruction, or caries leading to pulp necrosis.  This article reports a rare occurrence of fusion/gemination in the third molar region.
- Concrescent teeth - two teeth fused by coalescence of their cementum;
- Fused teeth - teeth joined by dentine in their developmental stage;
- Geminated teeth - fusion of a tooth with a supernumerary one; and
- Dens in dente.
| Case Report|| |
A 25-year-old female reported to the outpatient department with a complaint of pain in the right lower back tooth region since 1 month. Past medical and dental histories were not contributory. On intraoral examination, partial appearance of the crown of 48 was noted with redness of the gingiva surrounding the tooth and swelling of the pericoronal flap of gingiva [Figure 1]. Considering the inflamed gingiva and the partial appearance of 48, a provisional diagnosis of pericoronitis with impacted tooth in relation to 48 was made. A radiographic examination was done.
Orthopantomograph (OPG) revealed the presence of an anomalous tooth in the third molar region [Figure 2]. It appeared like two crown structures which were fused and the root portion having three roots. The pulp chamber appeared to be continuous for both the crowns, and the root canal of the middle root appeared to be large when compared to the other two roots. A radiographic diagnosis of gemination was arrived at. The patient was subjected to surgical extraction and tooth was examined thoroughly to differentiate it from fusion.
The occlusal surface of the tooth appeared to be continuous [Figure 3], but on the buccal and lingual surfaces [Figure 4] and [Figure 5], the two crowns were separated by a marked groove which caused incomplete division of the tooth. There was a common root for both the crowns, which confirmed incomplete division of the tooth. The extracted tooth was imaged using radiovisiography (RVG) [Figure 6] and [Figure 7] which again confirmed gemination. Diagnosis of gemination of the tooth in relation to 48 was thus confirmed.
| Discussion|| |
Fusion and gemination are developmental anomalies with unusual anatomy. Geminated teeth are developmental anomalies of the tooth shape that arise from an abortive attempt by the single tooth bud to divide, resulting in a bifid crown or trifid crown.  Clinically, it may be difficult, if not impossible, to differentiate fusion from germination when supernumerary teeth are involved. , This similarity of clinical features causes much confusion. Brook and Winter (1970)  proposed that these anomalies be referred to by a neutral term such as "double teeth."  Mader (1979)  emphasized the similarity of the clinical appearance of fused and geminated teeth and suggested to refer to teeth joined together by dentine as "fused teeth."
Distinguishing joined teeth as either germination or fusion is often difficult. Several clinical and radiographic criteria are used to differentiate between the two entities. Fusion is the incomplete attempt of two tooth buds to fuse into one, whereas gemination is the incomplete attempt of one tooth bud to divide into two. In the absence of an involvement of a supernumerary tooth, a full complement of teeth usually means that the phenomenon represents gemination and less than full complement of teeth usually indicates fusion. Radiographically, in case of fusion, there are usually two separate canals, whereas in gemination, there is usually one large common root canal. In the case presented here, there was no reduction in the number of teeth; moreover, due to the presence of a large root canal in the middle root, we arrived at the diagnosis of gemination of 48. According to previous reports, communication between the pulp chambers of fused or geminated teeth is a common feature. It should be removed to facilitate a straight-line access to the root canals. ,,,
There are different treatment approaches. One of the deciding factor to retain or extract these teeth, is esthetic quality. One possible treatment involves their extraction and conversion crowning of the adjacent teeth. The second option is surgical division of the double teeth when the degree of fusion is mild. The third option is selective grinding in order to reduce the width. A fourth option is to extract and replace these teeth. In the present case, as the anomalous tooth was a third molar and it was causing pericoronal infection, the patient was subjected to surgical extraction rather than performing conservative procedures to save the tooth.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]