The orthopantomography (OPG), also called panoramic radiography, is a widely used extraoral radiographic technique and great diagnostic utility in the dental clinic, since it allows the visualization of elements that could not be seen with conventional intraoral or extraoral techniques.
In this post we will update you on the various applications of the OPG, talk about observable structures when the technique is well performed, tell you how to obtain a perfect radiographic image and avoid common errors, and give you some clues to decide if the best thing for your dental clinic is a panoramic X-ray equipment or a CBCT (Cone Beam Computed Tomography). Are you ready? Let's begin!
What is an orthopantomography and what is it used for?
The orthopantomography is a radiological technique used in dentistry, especially in orthodontics, which allows obtaining a complete panoramic image of the teeth, mandible and maxilla. It is performed using special equipment called orthopantomograph, which can be conventional or digital. This equipment is essential for diagnosis in the dental clinic, and is widely used in oral surgery, implantology, orthodontics, periodontics, and oral pathology.
The OPG has various applications in the dental clinic, including:
- Detection of injuries, diseases and disorders of the jaws, teeth and their supporting structures.
- Confirmation of the diagnosis of some diseases.
- Assessment of the extent of a bone pathology.
- Evaluation of included or impacted teeth.
- Diagnosis of fissures or fractures, considering their displacement and consolidation.
- Evaluation of patterns of tooth eruption, growth and development.
- Detection of foreign bodies.
- Diagnostic complement to intraoral radiographs.
- Obtaining information during dental procedures.
- Assessment of growth and development.
What structures are seen on an orthopantomography?
For the technique to be considered acceptable, a panoramic radiography should clearly show the following anatomical structures:
- Teeth: The dentition should show a smooth curve at the smile line, with an easily distinguishable gap between the upper and lower teeth. The posterior teeth should be of normal size and there should not be excessive overlap between the premolars. The apices of the anterior teeth must be complete and the crowns must be visible on the radiographic image.
- Sinuses and nose: The soft tissues of the nose and its cartilage should be clearly visible on the radiographic image. The shadow of the hard palate should be prominent and some ghost images of the palate may be visible in the maxillary sinuses. In the image the tongue must be observed in contact with the palate.
- Mandibular condyles: Both condyles should appear centered in the radiographic image, with similar size and height in relation to the horizontal plane.
- Ramus of the mandible and cervical spine: The ramus of the mandible should be similar on both sides of the image. The vertebral column, when visible, must not overlap the mandibular ramus and the distance between them must be equal on both sides.
- Mandibular body : The lower cortex of the mandible should show a uniform and continuous image. There should be no ghost images or double images of the hyoid bone and the midline of the mandible and maxilla should not be magnified.
What mistakes should be avoided in an orthopantomography?
⚠️ Ghost Image
A ghost image consists of a radiopaque artifact that is visible in a panoramic image and is caused by the double penetration of the X-ray beam into an object. This ghost image looks similar to the real image, but appears on the opposite side of the film, is larger and taller than the real image, and is fuzzy.
Solution: Ask the patient to remove all metallic or radiodense objects, such as glasses, earrings, piercings, necklaces, removable dentures, removable orthodontic appliances, etc.
Image 1: ghost images
⚠️ Lead Apron Artifact
Radiation protection is essential for the patient and wearing a lead apron and a thyroid collar is essential during X-ray exposure It may happen that when the apron or collar are poorly positioned, they appear in the image as a cone-shaped radiopaque artifact that makes diagnostic information difficult.
Solution: Position correctly the patient's protection elements and choose those that allow a more comfortable and easy fit to avoid positioning errors. Take a look at our lead aprons and find the one that suits you best.
Image 2: an artifact corresponding to the lead apron is observed
⚠️ Radiolucent shade on anterior teeth
This error can occur for two reasons, the first is when the patient's lips are not closed on the bite-tab during the panoramic X-ray , this can cause a shadow to be seen dark radiolucent that blocks the view of the front teeth. The second reason is that the tongue is not resting against the palate during the orthopantomography, this can cause a dark radiolucent shadow to be seen on the apices of the upper teeth, making diagnosis difficult.
Solution: Explain correctly to the patient the importance of remaining still, with the lips closed on the bite tongue and the tongue resting on the palate.
⚠️ Hard palate and floor of nasal cavity superimposed on roots of upper teeth
⚠️ Loss of detail in larger, diffuse upper incisors
⚠️ Flat or upward curved smile line
The cause of these errors could be attributed to the incorrect placement of the Frankfurt plane, with the head tilted backwards. This occurs when the patient's chin is too high or tilted upward, causing the Frankfurt plane to tilt.
Solution: Position correctly the patient to avoid these errors. Remember that the Frankfurt cephalometric plane must be parallel to the ground and we can identify it because it is that imaginary line that passes from the infraorbital point and through the upper edge of the external auditory canal (top of the ear hole) or tragus.
Image 3: Flat or upward curved smile line
⚠️ Little detail in the anterior apical region, blurred lower incisors
⚠️ Absence of condyles in the radiographic image
⚠️ Exaggerated smile line or like a bird's beak
These errors occur due to a situation contrary to the previous one, that is, the patient has the Frankfurt plane tilted downwards and the solution, of course, is the same as the previous one: position correctly the plane parallel to the ground.
Image 4: exaggerated smile line
⚠️ Blurred or distorted front teeth
The bite tongue of the panoramic X-ray unit has a groove in which to position the teeth. If this groove is not used and the teeth are positioned in front of or anterior to the focal canal, they are they will look thinner or out of focus and if, on the contrary, the teeth are positioned behind the groove, they will look blurry, wide and also out of focus.
Solution: Ask the patient to use the groove to position their teeth on the bite tongue.
⚠️ One side of the x-ray is magnified and the other side is reduced
This occurs because the sagittal plane is not correctly centered, therefore, the magnification of the ramus and of the posterior teeth will be asymmetric in the orthopantomography.
Solution: Center the patient's head and check that the sagittal plane is right in the middle and is perpendicular to the floor. Normally the teams have guides that help to position the planes correctly.
Image 5: One side is enlarged and one side diminished in OPG because the patient's head is not in the sagittal plane.
⚠️ The spine is radiolucent seen in the center of the radiographic image
It is an error that can be caused by a bad posture of the patient, who is not upright. The radiolucency present in the center of the image makes diagnosis difficult.
Solution: Position the patient correctly, adjusting the radiographic equipment with the chin rest at his height. A piece of advice is for the patient to hold the handle with both hands from the bottom part, in this way their shoulders will be lower and their back more upright. In addition, he should put his feet forward slightly, noting that he is going a little backwards.
Is a panoramic X-ray machine or a CBCT (cone beam) machine better?
The answer to this question has many variables. If your specialty is implantology or maxillofacial surgery, most likely your best option would be a CBCT due to the greater number of useful benefits that can offer you The precision in the measurements made in the preoperative examinations in maxillofacial surgery and implantology is crucial for the success of the surgical procedure and in the postoperative period. To assess the amount of existing mandibular bone, the panoramic radiograph is the most commonly required radiological examination and, in some cases, it is the only one used in the preoperative process.
Panoramic radiographs suffer from distortion because they do not comply with basic projection principles, resulting in an increase in image size compared to structures. This limits the precision of the measurements made in the exam.
It is of great importance to use more precise technologies that provide a greater amount of data at a more favorable cost for the patient and the dentist. An example of this is the Cone Beam CT (CBCT) system , which has revolutionized the area of implantology and maxillofacial surgery, as it provides a wide variety of both two-dimensional and three-dimensional examinations with a ratio of 1:1 with respect to the anatomical and/or pathological structures of interest, and with a much lower cost-dose compared to TC equipment used in medicine.
1020S CBCT 3-in-1 Dental Scanner: Panoramic, TC and Cephalometric X-ray Equipment
If you are undecided, don't worry because at Dentaltix we have the CBCT intelligent dental scanner, in which, in addition to enjoying all the benefits of a 3D device , you can use it as panoramic X-ray equipment and considerably reduce metal artifacts, as well as distortion and overlapping.
In addition, this equipment is very smart, since it has an intelligent Pano 3D system, capable of automatically generating 33 slices of TC panoramic images of 0.8 mm thickness, adapted to the shape of each patient's maxilla and mandible with just a touch. It allows 16 TC panoramic images to be displayed simultaneously on the screen, resulting in a more intuitive and convenient experience compared to traditional panoramic. Do you want to meet it? Take a look!
Go to Bondent 3D-1020S Smart Dental Scanner
In conclusion, orthopantomography is and will continue to be a great diagnostic technique due to its great advantage of providing the complete anatomy of the maxillofacial area with a low radiation dose for the patient , although it is clear that it is not recommended or appropriate for diagnoses that require a high level of detail, such as in the case of early bone loss or incipient caries, since it is necessary to visualize small anatomical details, which are appreciable in the images obtained with intraoral radiographs.
The effectiveness of any diagnostic procedure is measured by the amount of information obtained through its use. In the case of orthopantomography, there are several very specific factors that can negatively affect the diagnostic quality of the images. The main factor is the inadequate position of the patient. That's why it's important to be aware of these factors and make sure to monitor the quality of your panoramic X-rays, using only those that are free of errors.
We hope that our post has served you to refresh your knowledge and avoid some frequent errors in this radiographic technique. Do not forget to follow us on our social media to always be informed about the latest news in the dental sector. See you soon!