Russell KA, Folwarczna MA. Mesiodens – diagnosis and management of a common supernumerary tooth. J Can Dent Assoc. 2003; 69:362-366
Hidalgo-Sanchez O, Leco-Berrocal MI, Martinez-Gonzalez JM. Metaanalysis of the epidemiology and clinical manifestations of odontomas. Med Oral Patol Oral Cir Bucal. 2008; 13:730-734
Mossaz J, Kloukos D, Pandis N Morphologic characteristics, location, and associated complications of maxillary and mandibular supernumerary teeth as evaluated using cone beam computed tomography. Eur J Orthod. 2014; 36:708-718 https://doi.org/10.1093/ejo/cjt101
Haney E, Gansky SA, Lee JS Comparative analysis of traditional radiographs and cone-beam computed tomography volumetric images in the diagnosis and treatment planning of maxillary impacted canines. Am J Orthod Dentofacial Orthop. 2010; 137:590-597 https://doi.org/10.1016/j.ajodo.2008.06.035
This case report discusses the incidental finding of a very unusually positioned supernumerary tooth in a 9-year-old male patient which presented to our oral and maxillofacial department. Along with two other unerupted conical supernumeraries in the anterior maxilla, this supernumerary was uniquely located within the nasopalatine canal extending into the base of the right nasal fossa. The abnormal morphology of this supernumerary was consistent with the presentation of a compound odontoma.
CPD/Clinical Relevance: This report highlights the value of three-dimensional imaging in managing such cases, surgical approaches to remove the impacted teeth and evaluates the need for removal of these supernumerary teeth.
Article
A supernumerary tooth is defined as an additional tooth to the normal dentition. The prevalence of supernumerary teeth in the permanent dentition is reported to range between 0.1% and 3.8% for the White populations, and between 2.7% and 3.4% for sub-Saharan African and Asian populations.1 They tend to occur more frequently in males compared to females with a ratio of 2:1.1,2 Single supernumerary teeth have been most commonly reported in 76–86% of cases. Multiple supernumerary teeth in an individual have been reported as a pair in 12–23% of cases, and more than two teeth have been reported in less than 1%.3
Supernumeraries may present as an isolated finding, or as part of a syndrome such as cleidocranial dysostosis, cleft lip and/or palate and Gardner's syndrome. They often present among family members; however, it does not follow a Mendelian inheritance pattern. The most widely accepted theory for the aetiology of supernumerary teeth is the localized and independent hyperactivity of the dental lamina.1,2
While they can remain asymptomatic, various complications can arise from the presence of supernumerary teeth. They can cause delayed eruption or impaction of permanent teeth, crowding, displacement, dilaceration, root resorption of neighbouring teeth as well as cyst formation.1,2
The most common type of supernumerary is a mesiodens, which is located between the central incisors, with a prevalence of 0.15–1.9% in the general population.4 They can be further classified according to their morphological type: conical; tuberculate; supplemental; or odontoma. Odontomas are recognized as the most common type of odontogenic tumours, accounting for 30–40%. They are considered to be benign hamartomatous malformations and are classified as either compound or complex, depending on their conformation.5 A meta-analysis by Hidalgo-Sanchez et al demonstrated 41.2% of cases with odontoma lesions in the anterior maxilla – more than any other site. As a result, the upper incisors and canine teeth are those most frequently affected by odontomas.5
Mossaz et al evaluated the type, location and proximity of supernumerary teeth to adjacent structures using cone beam computed tomography (CBCT) scans. Mesiodentes represented the most common type of supernumerary in 49/101 (48.5%) of cases. Of the mesiodentes, their relationship to the nasopalatine canal were reported as: 38.8% with external contact; 8.2% with partial perforation of the canal; and 2.0% as being located within the canal. Of mesiodentes, 8.2% were observed having partial perforation of the cortical bone of the nasal floor.6
Case report
A 9-year-old patient was referred by his orthodontist to the Ashford and St Peter's Hospital joint dento-alveolar multidisciplinary clinic regarding the presence of two unerupted supernumerary teeth in the anterior maxilla. The patient was medically fit and well, with no allergies. The removal of these teeth was requested prior to commencing orthodontic treatment. His pre-treatment clinical photographs are shown in Figures 1–3.
Class I incisor relationship on a Class I skeletal base with average vertical proportions;
Permanent dentition with upper and lower 7–7 present, with the exception of a missing lower incisor;
Normal overjet and overbite;
Palatally positioned upper second premolars (UR5, UL5) and upper lateral incisors (UR2, UL2), with associated crossbite;
Molar relationship: Class I on the right and ¼ unit Class III on the left;
Two midline supernumeraries in the anterior maxilla were observed on the panoramic view (Figure 4).
Figure 4. Panoramic radiograph showing the presence of two supernumerary teeth in the anterior maxilla.
A CBCT scan was taken to assess the proximity of the supernumerary teeth in relation to the roots of the upper incisor teeth and obtain precise localization to aid surgical planning. The CBCT highlighted the palatal position of the two supernumeraries in question, confirming the absence of root resorption or cystic change. In addition, the scan revealed the presence of a very atypical third odontomatous supernumerary – reported by a dental and maxillofacial radiologist as follows:
‘There is a further, third very anomalous supernumerary tooth lying centrally, just to right of the midline and within the lateral margin of the incisive canal. The canal itself is slightly dilated to a diameter of 6 mm. This tooth has a rudimentary crown and very elongated curved root and measuring approximately 17 mm in length. The root passes up the incisive canal and into the base of the right nasal fossa. No cystic change is noted. This is a very unusual presentation for a supernumerary tooth, appearing to represent very ectopic dental tissue developing within the nasopalatine duct.’
The positioning, size and morphology of the third supernumerary tooth can be seen in Figure 5.
Following clinical examination and radiographic investigations, treatment options were discussed with the patient and parents as part of informed consent, including the risks and benefits of any surgical intervention. The patient was keen to seek orthodontic management for his malocclusion, and therefore arrangements were made for this patient to undergo a general anaesthetic for the surgical removal of all three supernumerary teeth. Owing to the position of the third supernumerary tooth in the nasopalatine canal, the patient and parents were informed of the risk of temporary or permanent altered sensation to the anterior palate post-operatively. The surgical site was prepared and a palatal flap was raised in order to expose the supernumerary teeth. The two conical supernumerary teeth were initially located and removed easily with simple elevation. Following this, the incisive canal was opened and an alveolar bone gutter was made using a surgical handpiece and bone rongeurs. The third anomalous supernumerary was removed intact. Surgicel was placed and the palatal flap was repositioned with 3-0 Vicryl rapide mattress sutures. There were no reported complications in the immediate post-operative healing period and the patient was subsequently discharged back to his orthodontist to commence fixed appliance treatment. Figure 6 shows a post-operative photograph of the supernumerary teeth following removal. The relative positioning of the tooth is displayed in relation to the CBCT sagittal view in Figure 7.
Figure 6. Post-operative photograph of the three supernumerary teeth.Figure 7. The anomalous supernumerary tooth superimposed on the CBCT sagittal view.
Discussion
From an orthodontic perspective, supernumerary teeth can have an effect on adjacent teeth and may interfere with tooth movement. Removal of these teeth is often indicated prior to commencing any orthodontic treatment. A panoramic radiograph is important in initial orthodontic assessments by both general dental practitioners and orthodontists alike. In this case report, the presence of two supernumerary teeth were highlighted as potential complications prior to orthodontic treatment.
Conventional two-dimensional radiographic images, such as panoramic, cephalometric, peri-apical and occlusal views, are very useful diagnostic aids in cases such as this. However, the images do not accurately determine the precise location of supernumerary teeth and their relationship to neighbouring structures. Furthermore, for panoramic radiographs, structures in the anterior maxilla can often appear obscured. In this case report, the third supernumerary tooth was an incidental finding on the CBCT scan and not identified from the panoramic view alone. It is plausible that an occlusal radiographic view, had it been taken, may have identified the additional supernumerary tooth. However, the CBCT images allowed for the analysis of the precise shape, positioning and relationship to adjacent structures. Furthermore, it was important for aiding with treatment and surgical planning. A study among orthodontists by Haney et al compared the diagnostic value of two-dimensional radiographs with three-dimensional CBCT images. The orthodontists had a significantly different perception of localization, and greater confidence in diagnosis and treatment planning with the CBCT images compared with routine radiographs.7
The surgical approaches used to remove supernumerary teeth are largely dependent on their shape and positioning, which further emphasizes the value of CBCT scans. The anomalous supernumerary located in the nasopalatine canal could have been surgically removed with either palatal access or from the floor of the nose. However, with the shape and angulation of this tooth observed on the CBCT, it appeared more favourable and less invasive to remove this tooth with palatal access. In addition, palatal access was also required to remove the other two conical supernumeraries. Sectioning is often required to facilitate the removal of large curved teeth; however, this was not required as it was possible to remove the whole tooth intact. Given the rudimentary crown, unusual curvature and length of this supernumerary, it was consistent with the presentation of a compound odontoma with ectopic dental tissue.
Following review of the literature, there appears to be only one documented case report describing the presence of a supernumerary tooth within the nasopalatine canal. In that particular case, the supernumerary tooth was also an incidental finding following a CBCT scan for an implant assessment on a 50-year-old male.8 However, this was a conical supernumerary tooth representing more normal dental tissue and morphology, compared to an odontomatous presentation.
Conclusion
This case report highlights the low incidence of supernumerary teeth located within the nasopalatine canal. Furthermore, the atypical morphology observed in this case report makes this a very rare presentation altogether. It also emphasizes the value of three-dimensional imaging modalities, such as CBCT scans, in aiding with diagnosis, treatment planning and surgical approaches.
