DOUBLE TOOTH: REPORT OF TWO UNIQUE CLINICAL CASES.
Double tooth is the general term that is used to describe fusion and gemination in which one tooth is conjoined with another. Fusion is defined as two separately forming teeth joined together while gemination refers to partial development of two teeth from a single tooth bud. In clinical practice fusion and gemination are often confused with one another. This report describes two unique clinical cases of double tooth in maxillary anterior region, and the intent of this report is to facilitate young clinician to differentiate fusion from gemination so that successful diagnosis of double tooth can be reached with certainty.
Key Words: Gemination, Fusion, Supernumerary teeth, Double tooth.
Dental abnormality of the structure and number of teeth can occur in the primary and permanent dentition.1,2 Double tooth is the most common term that has been used to describe anomalies (Fusion or Gemination) in which one tooth is conjoined with another.3 Gemination is defined as the partial development of two teeth from a single tooth bud following incomplete division.4
While fusion is defined as two separately forming teeth joined together.5 Differential diagnosis between gemination and fusion can be made radiographically, as in gemination two crowns are present, either totally or partially separated, with a single root and one root canal while in fusion crowns are united by enamel and/ or dentine, but there are two roots or two root canal in a single root.6 Double tooth may influence alignment of teeth, interdigitation and arch symmetry causing ectopic eruption, delayed eruption of other teeth or some form of malocclusion in human dentition.7,8 The exact cause of double tooth is unknown.9
Grover and Lorton10 claimed that local metabolic interferences that occur during tooth germ morpho-differentiation could be a cause. There is some evidence that the condition has a familial tendency. It may also be associated with syndromes such as achondroplasia and chondroectodermal dysplasia.
Double tooth is more commonly found in deciduous dentition, is more prevalent in the anterior maxillary region, but they can also be seen unilaterally or bilaterally in either the maxillary or mandibular permanent dentition.3,12-14 Prevalence of fusion and gemination is extremely limited in orthodontic cases with prevalence of 0.23% and 0.07%, for fusion and gemination respectively.10 In Pakistan, study conducted by Khan SQ15 reported that double tooth was present only in one orthodontic patient.
The aim of reporting these two unique clinical cases is to help clinicians differentiate fusion from gemination so that successful diagnosis of double tooth can be reached without any ambiguity.
CASE REPORT 1
Eighteen year old boy presented to orthodontic department with the complaint that he does not like the way his teeth look. Medical and dental histories were not significant. Upon extra-oral examination, the patient had no visible asymmetry, straight profile, incompetent lips and normal facial height. Intraorally, except for third molars, all permanent teeth were present in both maxilla and mandible. Oral hygiene was adequate with dental caries present bilaterally in mandibular first permanent molars. Severe crowding was present in the maxillary arch and upper midline was shifted to right side. In mandibular arch, there was severe crowding and midline was shifted to left side. Boltons analysis showed maxillary excess. Molar relationship was Angle's class I on both sides. Overjet and over bite were 2mm.
Width of right lateral incisor was greater than the left lateral and it was greater even when compared with the average mesiodistal width of lateral incisor. On right side of the maxillary arch, two lateral incisors seemed to be joined together. Careful observation of large tooth revealed an indentation on the labial and palatal surface running from the incisal edge to the cervical margin almost dividing the crown into two halves and prominent cingulum on the palatal surface (Fig 1).
Periapical radiograph of the double tooth revealed two separate pulp chambers giving rise to two separate root canals terminating in two apical foramina. The double tooth was clinically asymptomatic neither irritating to the tongue during speech or mastication nor interfering with occlusion. Patient was more concerned with the crowding in both the jaws. Dental Panoramic radiograph showed the presence of a normally developed permanent dentition.
Oral hygiene prophylaxis was performed to improve the patient's oral hygiene and later patient agreed to undergo orthodontic treatment during which double tooth was extracted to deal with crowding in the upper arch. Ground section of the double tooth revealed two separate pulp chambers and two separate canals in the tooth (Fig 2).
CASE REPORT 2
Seventeen year old girl presented to orthodontic department with the complaint that she does not like her front tooth and feels that it is bigger in size than normal. Medical and dental histories were not significant. Upon extra-oral examination, the patient had no visible asymmetry, convex profile, incompetent lips and increased lower facial height. Intraorally, supernumerary tooth (supplemental tooth), resembling permanent lateral incisor, was present palatally (Fig 3). All permanent teeth were present in both the jaws, except for third molars. Oral hygiene was not optimal but no dental caries was present in dentition. Crowding was present in the maxillary arch along with midline distema. Crowding was also present in the mandibular arch and the lower midline was shifted to right side.
Molar relationship was Angle's Class I subdivision II on right sides. Overjet was 6mm while over bite was 2mm and clinically width of right central incisor was greater than the left central and even when compared with the average mesiodistal width of central incisor (Fig 4). Careful observation of large tooth revealed that the crowns of the teeth appeared to be melded together, without any distinct labial groove and clinical diagnosis of double tooth was reached. An indentation on the palatal surface running from the incisal edge to the cervical margin almost dividing the crown into two halves was visible with prominent cingulum.
Periapical radiograph of the double tooth revealed a single tooth with two separate root canals, originating from separate pulp chambers and terminating in two apical foramina. The double tooth was clinically asymptomatic neither irritating to the tongue during speech or mastication nor interfering with occlusion. Patient complained of the bulkiness in the area and aesthetics was the main concern for her because of the large size of one central incisor when compared with the other. Panoramic radiograph showed the presence of a normally developed permanent dentition. No treatment was provided as patient refused to undergo any form of orthodontic treatment.
Orthodontic treatment is required for management of double tooth as it can lead to malocclusion and can adversely affect patient's aesthetics. Double tooth can be due to fusion or gemination. Fusion results when development of two tooth germs takes place so close that they come into contact and fuse before calcification starts.5 Some researchers believe that physical pressure and force generated during growth causes contact between two tooth germs.16 The precise etiology of fusion is still unknown. Fusion is more common in primary dentition than the permanent dentition. Data available in the literature points out that the prevalence of fusion ranges from 0.5%-2.5% according to the population surveyed.17 Fused teeth are usually larger than normal size with total or partial union of dentin and with two separate root canals.
Mandibular anterior teeth are affected more frequently than maxillary, depending upon racial, genetic or geographic factors.18 Fusion is observed to occur unilaterally and can be suspected when the number of teeth in the arch is found to be reduced and radiographically two roots are seen in relation to one crown.19,20
On the other hand, gemination is defined as incomplete division of one tooth germ, resulting in the formation of two partially or completely separated crowns formed on a single root.19 Although the prevalence rate is variable in individual reports, the overall prevalence appears to be approximately 0.5% in the deciduous teeth and 0.1% in the permanent dentition.4
It is frequently observed in the anterior teeth but can also affect molars and bicuspids. Gemination can usually be distinguished from fusion by the presence of a full set of teeth with an incompletely divided tooth. "Two Tooth Rule" proposed by Mader's21 can be a convenient way in differentiating between fusion and gemination. When teeth in arch are lesser in number after counting fused teeth as one, than the term fusion can be considered. But if abnormal tooth is counted as one and the number of teeth in dental arch are normal, then most likely it is the case of gemination or fusion between normal and supernumerary teeth.
Due share must be given to restorative and orthodontic treatment modalities when management of double tooth is planned. Its presence can lead to tooth size discrepancy and may influence teeth alignment, occlusion and arch symmetry.8,22 Morphology of double tooth is not aesthetically pleasing as very deep defects, in the form of groove or fissure occurs at the junction between the two teeth involved. Extension of these fissures or groves subgingivally makes the tooth susceptible to accumulation of bacterial plaque in these defeats leading to caries and periodontal problems. Strict maintenance of oral hygiene is essential to maintain good periodontal health while resin restorations or sealants can be used in deep fissures and grooves to reduce caries risk in these teeth.
As morphology of the double tooth varies greatly, so will be its management. Different treatment modalities like orthodontic correction, selective grinding and surgical separation followed by pulp therapy of the retained segment are available for double tooth.23 For every patient, after correct diagnosis, best treatment modality needs to selected so that excellent results can be achieved in restoring form, function and aesthetics.
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2 Hamasha AA, Al-Khateed T. Prevalence of fused and geminated teeth in Jordanian adults. Quintessence Int 2004; 35: 556-59.
3 Duncan WK, Helpin ML. Bilateral fusion and gemination: a literature analysis and case report. Oral Surg Oral Med Oral Pathol 1987; 64: 82-87.
4 Nandini DB, Deepak BS, Selvamani M, Puneeth HK. Diagnostic Dilemma of a Double Tooth: A Rare Case Report and Review. J Clinical Diag Research 2014; 8(1): 271-72.
5 Rajeswari MRC, Ananthalakshmi R. Fusion - Case Report and Review. Indian J Multidiscip Dent 2012; 2(2): 441-42.
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15 Khan SQ, Ashraf B, Khan NQ, Hussain B. Prevalence Of Dental Anomalies Among Orthodontic Patients. Pak Oro Dent J 2015; 35(2): 224-27.
16 White S. Oral radiology principles and interpretation 5th ed, St. Louis: Mosby Inc 2004; 337-38.
17 Grahnen et al. Numerical variation in primary dentition and their correlation with the permanent dentition. Odont Rev 1961; 12: 248-57.
18 Olivan-rosas G, Lopez-jimenez J, Gimenez-prats MJ, Piqueras-Hernandez M. Considerations and differences in the treatment of a fused tooth. Med Oral 2004; 9: 224-28.
19 Neville DW, Damm DD, Allen CM, Bouquot JE. Color Atlas of Clinical Oral Pathology. 2nd ed. Baltimore, MD: Williams and Wilkins; 1991: 62-64.
20 Hernandez-Guisado JM, Torres-Lagares D, Infante-Cossio P, Gutierrez-Perez JL. Dental gemination: report of case. Med Oral 2002; 7: 231-36.
21 Mader CI. Fusion of teeth. J Am Dent Assoc 1979; 98: 62-64.
22 Bolton W. The clinical application of a tooth size analysis. Am J Ortho 1962; 48: 504-29.
23 Pearson AI, Willmot DR. Combined surgical and orthodontic treatment of bilateral double teeth: A case report. Int J Pediatr Dent 1995; 5(1): 43-47.
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|Publication:||Pakistan Oral and Dental Journal|
|Date:||Jun 30, 2016|
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