|Year : 2011 | Volume
| Issue : 3 | Page : 260-263
Vertex occlusal radiography in localizing unerupted mesiodentes
P Chalakkal1, AM Thomas2, F Akkara3, Ida de Noronha de Ataide4
1 Department of Pedodontics & Preventive Dentistry, Goa Dental College and Hospital, Bambolim, Goa, India
2 Department of Pedodontics & Preventive Dentistry, Christian Dental College and Hospital, Ludhiana, Punjab, India
3 Department of Oral and Maxillofacial Surgery, Goa Dental College and Hospital, Bambolim, Goa, India
4 Department of Coservative Dentistry and Endodontics, Goa Dental College and Hospital, Bambolim, Goa, India
|Date of Web Publication||10-Oct-2011|
Department of Pedodontics & Preventive Dentistry, Goa Dental College & Hospital, Bambolim - 403 202, Goa
| Abstract|| |
The aim was to compare the vertex occlusal projection with the anterior maxillary occlusal projection in localizing the position of mesiodentes. Mesiodentes were observed in an 8-year-old boy with an anterior maxillary occlusal radiograph. A vertex occlusal radiograph was taken to compare it with the former in terms of mesiodentes localization with respect to the maxillary central incisors. The vertex occlusal radiograph provided greater details of the position and proximity of mesiodentes with respect to the long axis of maxillary central incisors in comparison to the anterior maxillary occlusal radiograph. Vertex occlusal radiography is an important diagnostic tool in diagnosing the presence, position, and proximity of mesiodentes with respect to the long axis of normally aligned maxillary central incisors. However, it is not recommended for routine use in a patient as its radiation dose is higher than conventional intraoral radiographic methods.
Keywords: Mesiodens, mesiodentes, occlusal, radiograph, vertex
|How to cite this article:|
Chalakkal P, Thomas A M, Akkara F, Ataide IN. Vertex occlusal radiography in localizing unerupted mesiodentes. J Indian Soc Pedod Prev Dent 2011;29:260-3
|How to cite this URL:|
Chalakkal P, Thomas A M, Akkara F, Ataide IN. Vertex occlusal radiography in localizing unerupted mesiodentes. J Indian Soc Pedod Prev Dent [serial online] 2011 [cited 2013 May 23];29:260-3. Available from: http://www.jisppd.com/text.asp?2011/29/3/260/85838
| Introduction|| |
The supernumerary tooth in the midline between the two maxillary central incisors is referred to as "mesiodens," the plural of which is "mesiodentes."  Mesiodens account for 45-67% of all supernumerary teeth.  Its incidence in the permanent dentition ranges from 0.15% to 3.8%, whereas in the primary dention it ranges from 0% to 1.9%. ,,, The vertex occlusal projection has been largely appreciated for its accuracy in localizing a tooth of its horizontal and anteroposterior position with respect to the arch.
The objective was to compare the vertex occlusal projection with the anterior maxillary occlusal projection in localizing unerupted mesiodentes.
| Case Report|| |
An 8-year-old boy reported with the complaint of a large gap between his upper front teeth. His dental status was coincident with his chronological age. There was no relevant medical or family history and the patient was otherwise healthy.
An anterior maxillary occlusal radiograph revealed the presence of mesiodentes (two in number; [Figure 1]). However, the mesiodentes were unerupted. A vertex occlusal radiograph was also taken to help in localizing the mesiodentes with respect to the maxillary central incisors [Figure 2]. A written consent was obtained from the boy's parents for the same. The data for obtaining the vertex occlusal radiograph were as follows:
|Figure 1: Anterior maxillary occlusal radiograph showing two mesiodentes|
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Machine - SIEMENS BD-CX (Germany) radiography unit.
- Film - Kodak Ultra-speed occlusal.
- Collimator - light beam.
- Focus skin distance - 70 cm.
- Tube current - 200 mA.
- Tube voltage - 90 KVp.
- Exposure time - 0.5 seconds.
- Filter - 2.8 mm aluminum.
- Milliampere second - 100 mAs.
| Results|| |
The anterior maxillary occlusal radiograph could reveal only the presence of mesiodentes (two in number). However, the vertex occlusal radiograph provided a greater understanding of the situation which could not be interpreted from the former. Those were as follows [Figure 2]:
- The mesiodentes were located palatal to the central incisors, out of which, one was located palatal to 21, more toward the midline, while the other was palatal to 11.
- Each mesiodens had similar vertical inclination with the central incisor they were related to. This could be interpreted because they appeared as cross-sectioned images just like the central incisors.
- The proximity of each of the mesiodentes to the central incisors could be assessed.
- The proximity of one mesiodens to the other could be assessed.
| Discussion|| |
The maxillary occlusal projections used in dentistry are as follows:
- Anterior maxillary occlusal projection (vertical angulation of +65°; [Figure 3]a).
|Figure 3: (a) Anterior maxillary occlusal projection, (b) Cross-sectional maxillary occlusal projection, (c) True maxillary occlusal projection, (d) Vertex occlusal projection|
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- Cross-sectional maxillary occlusal projection (vertical angulation of +80°; [Figure 3]b).
- True maxillary occlusal projection (vertical angulation of +90°; [Figure 3]c).
- Vertex occlusal projection [Figure 3]d.
To obtain a vertex occlusal radiograph, the central ray needs to pass through the vertex of the skull and exit through the long axis of the maxillary central incisors. In doing so, the ray makes an anterior angle of 110° to the horizontal, as the maxillary central incisors are normally proclined at approximately 20° to the vertical [Figure 4].The image thus obtained makes the central incisors appear in cross-sections like "buttons with holes," where the holes represent pulp cavities of these teeth [Figure 2]. Therefore, any object near the central incisors will appear in the image with respect to the long axis of the central incisors.
The greatest advantage with the vertex occlusal radiograph is that the image of the central incisors does not superimpose on those of the mesiodentes. This makes positional interpretation of the mesiodentes with respect to the long axis of the central incisors simple and obvious. The vertex occlusal view is the clearest for horizontal and anteroposterior localization and is therefore preferred to assist in determining optimal surgical approach.  It has also been chosen as the gold standard for canine position because it was considered to provide clear, unequivocal information about the relationship of the unerupted tooth with the dental arch. 
A possible contraindication to the use of the vertex occlusal projection could be malaligned central incisors, where it might be difficult to project the rays parallel to the long axes of these teeth [Figure 5] and [Figure 6]. However, the angulation may be varied to obtain the desired result. The maximum radiation dose to obtain a vertex occlusal radiograph is 1.301 cGy.  The total energy imparted for each vertex occlusal view is 0.7 mJ (with an intensifying screen) compared to 0.4 mJ for an anterior maxillary occlusal view.  There also lies the disadvantage of having the rays pass through brain and eye tissues.
|Figure 6: Vertex occlusal radiograph of a patient with malaligned central incisors having mesiodens|
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The parallax method incorporating two periapical radiographs or a combination of occlusal and panoramic radiographs may also be used to localize a mesiodens. 
| Conclusions|| |
Vertex occlusal radiography is undoubtedly an important diagnostic tool in diagnosing the presence, position, and proximity of mesiodentes with respect to the long axis of normally aligned maxillary central incisors. However, it is not recommended for routine use in a patient as its radiation dose is higher than conventional intraoral radiographic methods.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]