January 1, 2000
by Leah Gibney-McCullough, DMD
This case report describes a seven-year-old female Caucasian who presented with a clinically missing permanent central incisor, an erupted supernumerary tooth, and a bilateral unerupted supernumerary tooth. The decision as to when or whether or not to extract is still a controversy.
Supernumerary teeth can be found anywhere in the mouth.1 They have a predilection for the maxilla2, and more specifically the premaxilla.3 Most commonly they occur between the central incisors and are termed mesiodens.1 The prevalence of supernumerary teeth has been estimated at 0.15-1.0% in Caucasian populations.1,2 In a study of 7,886 Canadians4, the occurrence of supernumerary teeth was .25% of which 81% were found in the maxilla. They are twice as common in boys than in girls1, and have been seen associated with syndromes of cleidocranial dysostosis and Gardner syndrome, as well as in cleft lip and palate patients.5,6,7 They may occur singly, bilaterally, erupted, nonerupted, or inverted.
Supplemental and rudimentary are two morphological forms of supernumerary teeth described by Primosch.7 Supplemental teeth are of normal shape and size and are often referred to as incisiform. They appear most commonly as extra maxillary and mandibular lateral incisors in the permanent dentition, and maxillary central incisors in the primary dentition.5 A supplemental tooth may exhibit a deep cingulum pit and have a coronal invagination.4 In the permanent dentition, the supplemental incisor is likely to result in excess overall tooth material in one arch (Bolton discrepancy). Deviation from the ideal tooth mass relationship will result in an adverse posterior occlusal relationship, abnormal overjet-overbite relationship, or crowding.8
Rudimentary teeth, the second morphological form of supernumerary teeth, can be divided into three subclassifications7:
The conical form is the most common subclassification. It is most often noted as a single palatally positioned midline structure, but may be unilateral or bilateral, and may even be inverted in some cases. The root is found to be completely formed. They rarely delay eruption, but often cause displacement of permanent teeth.7
The tuberculate form is barrel-shaped in appearance7 and is usually larger in comparison to the conical form of mesiodens . The width is usually equal to the length and it is often found with incomplete or total absence of root formation. They may be unilaterally or bilaterally positioned, rarely erupt, and are more likely to delay the eruption of adjacent teeth.5,7
The molariform subclassification closely resembles the morphology of a premolar.7 They appear to occur in pairs in the central incisor area and usually have complete root formation.
Supernumerary teeth are found most commonly in the permanent dentition, but may also be found in the primary dentition.2 In the primary dentition they are usually of the supplemental type, and often go unnoticed due to the primary spacing. They may also be confused with gemination or fusion,5 which may account for the lower reported incidence. Supernumerary teeth in both the primary and permanent dentition of the same child is likely to occur in more than one third of the cases.5,6
A seven-year-old female Caucasian presented for a recall exam on March 12, 1999 with a clinically missing #11 and a supernumerary erupting palatal to the #11 position (Fig. 1). The patient’s mother was concerned with the appearance of the new tooth. Medical and dental histories were non-contributory. There was no record of orofacial trauma. Familial history revealed that the father’s brother’s six-year-old son recently had an extra tooth extracted from the same area. A periapical radiograph was taken and revealed bilateral supernumerary teeth. The mother was advised to delay treatment until the supernumerary tooth erupted further, at which time it would be extracted. A second anterior occlusal radiograph revealed a rotation of tooth #21 (Fig. 2). The erupted supernumerary tooth and its unerupted bilateral counterpart were extracted under nitrous oxide sedation without complications on July 12, 1999 (Fig. 3).
There is much debate as to whether prophylactic removal of these supernumerary teeth is indicated. Most problems associated with supernumerary teeth are due to their ability to delay, displace, or prevent eruption of permanent teeth. This in turn can result in an unesthetic situation and parental concern.7 Rarely, nasal eruption (inverted conical type), cystic degeneration, root resorption and loss of vitality, or diastema formation may occur, therefore careful clinical and radiological monitoring is warranted. Alternatively, there may be no complications and unerupted supernumerary teeth may be noticed incidentally on radiographs of the permanent dentition.9
Proponents for prophylactic removal argue that the teeth serve little if any purpose, and the prognosis of surgical intervention is good, i.e., recurrence is extremely rare.7 On the other hand, Koch,10 in a retrospective study of 208 patients with supernumerary teeth found that more than one-third of the supernumerary teeth were being removed without other indications other than their mere presence. None of the 52 non-operated patients had any symptoms of pathology related to the supernumerary teeth. Thirty-seven percent showed progressive resorption, and 24% had a marked reduction of the pericoconary space.
Once it has been determined that removal is warranted, the timing is controversial. There are two camps: immediate vs. delayed. Immediate denotes removal within a short period of time following identification. Disadvantages of immediate intervention include potential damage to adjacent teeth, traumatic procedure for young children to endure, and performance of an unnecessary surgery if future complications fail to develop.7 Delayed denotes observation until adjacent root formation is complete, i.e., between eight and 10 years of age. Delaying intervention until the laterals develop may result in loss of eruption potential of central incisors, loss of arch space or a midline shift and more extensive surgery or orthodontics if permanent teeth fail to erupt.7
A compromised approach described by Primosch7 is to time surgical intervention based on tooth type and stage of eruption of permanent teeth. Conical forms should be observed for early eruption unless creating complications. Tuberculate or inverted conical forms that do not erupt should be removed immediately if causing adjacent permanent incisors to remain unerupted to prevent space loss. If the supernumerary tooth is highly placed (above apices), observation is indicated. After surgical removal, eruption of the permanent incisors may occur spontaneously or may require exposure and orthodontic traction. Neither patient age nor extent of root formation appears to influence spontaneous eruption of permanent incisors: scar tissue and amount of available space are of greater significance.2
In the present case, both supernumerary teeth were extracted to (1) alleviate parental concern (erupted supernumerary), (2) prevent a second surgical procedure (unerupted supernumerary), and (3) promote normal eruption and position of #21. From a surgical point of view it is imperative to know the buccolingual position of the supernumerary.
Dr. James Posluns, DDS, Dip. Ortho University of Toronto, Faculty of Dentistry.
Dr. Rudy Singh, DMD, 7 Argyle St. S. Renfrew, ON.
Dr. Leah Gibney-McCullough is currently in private practice in Petawawa, Ontario.
Oral Health welcomes this original article.
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