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260 Journal of IndIan SocIety of PedodontIcS and PreventIve dentIStry | Jul - Sept 2011 | Issue 3 | Vol 29 |

Case RepoRt

Vertex occlusal radiography in localizing unerupted mesiodentes

chalakkal P, thomas aM 1, akkara f2, Ida de noronha de ataide3 Department of Pedodontics & Preventive Dentistry, Goa Dental College and Hospital, Bambolim, Goa, 1Christian Dental College and Hospital, Ludhiana, Punjab, 2Department of Oral and Maxillofacial Surgery, 3Department of Coservative Dentistry and Endodontics, Goa Dental College and Hospital, Bambolim, Goa, India

correspondence: Dr. Paul Chalakkal, Department of Pedodontics & Preventive Dentistry, Goa Dental College & Hospital, Bambolim – 403 202, Goa. E-mail: [email protected]

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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.

Key words

Mesiodens, mesiodentes, occlusal, radiograph, vertex

Introduction

The supernumerary tooth in the midline between the two maxillary central incisors is referred to as “mesiodens,” the plural of which is “mesiodentes.”[1] Mesiodens account for 45-67% of all supernumerary teeth.[2] 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%.[3-6] 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:Machine – SIEMENS BD-CX (Germany) radiography unit.• Film–KodakUltra-speedocclusal.

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Chalakkal, et al.: Vertex occlusal radiography in localizing unerupted mesiodentes

261Journal of IndIan SocIety of PedodontIcS and PreventIve dentIStry | Jul - Sept 2011 | Issue 3 | Vol 29 |

• Collimator–lightbeam.• Focusskindistance–70cm.• Tubecurrent–200mA.• Tubevoltage–90KVp.• Exposuretime–0.5seconds.• Filter–2.8mmaluminum.• Milliamperesecond–100mAs.

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]:• Themesiodenteswerelocatedpalataltothecentral

incisors, out of which, one was located palatal to 21, more toward the midline, while the other was palatal to 11.

• Eachmesiodenshadsimilarverticalinclinationwiththe central incisor they were related to. This could be interpreted because they appeared as cross-sectioned images just like the central incisors.

• Theproximityof eachof themesiodentes to thecentral incisors could be assessed.

• Theproximityof onemesiodenstotheothercouldbe assessed.

Discussion

The maxillary occlusal projections used in dentistry are as follows:• Anteriormaxillary occlusal projection (vertical

angulation of +65°; [Figure 3a]).• Cross-sectional maxillary occlusal projection

(vertical angulation of +80°; [Figure 3b]).• True maxillary occlusal projection (vertical

angulation of +90°; [Figure 3c]).• Vertexocclusalprojection[Figure3d].

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

Figure 1: Anterior maxillary occlusal radiograph showing two mesiodentes

Figure 2: Vertex occlusal radiograph showing two mesiodentes

Figure 3: (a) Anterior maxillary occlusal projection, (b) Cross-sectional maxillary occlusal projection, (c) True maxillary occlusal projection, (d) Vertex occlusal projection




262 Journal of IndIan SocIety of PedodontIcS and PreventIve dentIStry | Jul - Sept 2011 | Issue 3 | Vol 29 |

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.[7] 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.[8]

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 [Figures 5 and 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.[9] 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.[10] There also lies the disadvantage of having the rays pass through brain and eye tissues.

The parallax method incorporating two periapical radiographs or a combination of occlusal and panoramic radiographs may also be used to localize a mesiodens.[7]

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.

References

1. Ray D, Bhattacharya B, Sarkar S, Das G. Erupted maxillary conical mesiodens in deciduous dentition in a Bengali girl – A case report. J Indian Soc Pedod Prev Dent 2005;23:153-5.

2. Zhu JF, Mauricio M, King DL, Henry RJ. Supernumerary and congenitally absent teeth: A literature review. J Clin Pediatr Dent 1996;20:87-95.

3. Sharma A, Gupta S, Madam M. Uncommon mesiodens – a report of two cases. J Indian Soc Pedod Prev Dent 1999;17:69-71.

4. Gallas MM, Garcia A. Retention of permanent incisors by mesiodens: A family affair. Br Dent J 2000;188:63-4.

5. Prabhu NT, Rebecca J, Munshi AK. Mesiodens in the primary dentition – A case report. J Indian Soc Pedod Prev Dent 1998;16:93-5.

Figure 4: Angulation of the vertex occlusal projection

Figure 5: Maxillary cast showing a malaligned central incisor

Figure 6: Vertex occlusal radiograph of a patient with malaligned central incisors having mesiodens

will appear in the image with respect to the long axis of the central incisors.




263Journal of IndIan SocIety of PedodontIcS and PreventIve dentIStry | Jul - Sept 2011 | Issue 3 | Vol 29 |

How to cite this article: Akkara F, Ataide IN, Chalakkal P, Thomas AM. Vertex occlusal radiography in localizing unerupted mesiodentes. J Indian Soc Pedod Prev Dent 2011;29:260-3.

Source of Support: Nil, Conflict of Interest: None declared.

6. Castillo Kaler L. The incidence of mesiodens in children of Hispanic descent. J Pedod 1986;10:164-8.

7. Cameron AC, Widmer RP. Dental anomalies. In: Cameron AC, Widmer RP, editors. Handbook of Pediatric Dentistry. 2nd ed. Mosby; 2003. p.193.

8. Fox NA, Fletcher GA, Horner K. Localising maxillary canines using dental panoramic tomography. Br Dent J 1995;179: 416-20.

9. Roth SF, Bohay RN, Barnett RB. Surface and internal absorbed doses in mandibular and maxillary occlusal radiography. J Can

Dent Assoc 1995;61:955-9.10. Wall BF, Fisher ES, Paynter R, Hudson A, Bird PD. Doses

to patients from phanto-. mographic and convention dental radiography. Br J Radiol 1979;52:727-34.

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