lntraoral Periapical radiographs (IOPA) are useful in the evaluation of teeth and their associated structures. IOPA radiograph can be taken by using two techniques; short cone technique or bisecting angle technique and long cone technique or paralleling technique.
Though the paralleling technique provides an image of teeth with minimal magnification, there is an inherent disadvantage of using this technique as special holders or position indicating devices are required to take the radiographs.
Paralleling technique in Periapical radiographs cannot be employed in children with a shallow palate and a shallow floor of the mouth. In small children, with primary dentition, size zero film should be used. In older children or in situations where a larger area has to be visualized, size 1 film should be used.
The indications for taking Periapical radiographs in children are given below:
- To determine the status of the periapical region in the deciduous and young permanent teeth.
- In the evaluation of pulp treatment or endodontic treatment.
- In the detection of developmental anomalies such as supernumerary teeth, un-erupted teeth or malformed teeth.
- To identify any pathology involving the primary teeth such as periapical pathology or internal resorption.
- To evaluate the status of the periodontal ligament
- In the diagnosis of pulp calcification, root resorption or root development
- Analysis of space in mixed dentition
- Diagnosis of traumatic injuries effecting pathological changes
Obtaining Child’s Co-operation for Periapical radiographs:
The following have been suggested for achieving better co-operation from the child patient during the Periapical radiographs procedure:
1. Acquaint the child with the dental X-ray machine and explain the procedure to him. Use words the child can understand.
2. Pre-set the timer and position the cone in the approximate angulation prior to placing the film when intra-oral radiographs are taken.
3. Obtain the confidence and the co-operation of the child. Take the easiest film for the patient first (e.g., upper anterior films).
4. Talk to the child so that you distract his attention and establish rapport and confidence.
For projection of the maxillary teeth, the head of the patient should be kept upright. The vertical angulation used are:
For the anterior teeth +50
For the premolars +30
For the molars +25
For the Periapical radiographs, the film is positioned on the palatal aspect of the teeth by using film holders. The tooth/teeth to be radiographed should come in the center of the film.
The central x-ray beam is directed in such a way that it hits the film almost perpendicularly. This principle should be followed to prevent magnification of the image and also to avoid a cone-cut appearance image formation in Periapical radiographs.
For projection of mandibular teeth, the following vertical angulations are used:
For the anterior teeth = -20
For the premolars = -10
For the first and second molars = -5
For the third molar = 0
For the lower anterior projection, the film is kept on the floor of the mouth, on the lingual side of the teeth, For the posterior projection, the film is kept on the lingual sulcus. Care should be taken while taking the Periapical radiographs of mandibular teeth to avoid soft tissue trauma due to the sharp margins of the film. The central x-ray beam is directed almost perpendicular to the film.
While employing the long cone technique in Periapical radiographs, the central x-ray beam is directed perpendicular to the long axis of the tooth and the long axis of the film, whereas, while employing the short cone technique in Periapical radiographs, the central x-ray beam is directed perpendicular to an imaginary bisector that bisects the angle formed by the long axis of the tooth and the film.