Radiographic Modalities and Views in Dentistry

What Is the Use of Dental Radiographs?

Dental Radiographs are a valuable diagnostic tool adjunct to clinical examination in diagnosing dental diseases. Dental radiography is mainly utilized to study endodontic, periodontal, or maxillofacial purposes like assessing pulp and root canal morphology, the status of alveolar bone and the inter-dental region, and detection of periapical pathologies and crown or root fractures.

For most cases in endodontics, dental radiology is especially useful for endodontic or root canal treatment. It helps in pre-treatment evaluation of roots and root canal morphology, assessing calcified canals, root curvatures, periapical lesions, or abscesses, determining working length during RCT (root canal treatment), and monitoring the quality and extent of root canal obturation material after treatment and its healing in a few days.

Correct use of appropriate imaging technology, correct interpretation by the radiologist or dental surgeon by following the principle of ALARA (as low as reasonably achievable), and cost-effectiveness form the crux of today’s dental radiology. Two-dimensional imaging uses periapical and panoramic radiographs that are most commonly utilized in dental practice.

How Are Dental Radiographs Classified?

Broadly, imaging techniques in dentistry can be classified as:

1. Intraoral and extraoral radiography.

2. Analog and digital radiography.

3. Ionizing and non-ionizing radiographic imaging.

4. Two-dimensional (2-D) and three-dimensional (3-D) imaging.

2-D and 3-D imaging are used more commonly by the dentist to highlight the differences and educate the patient about the technological upgrade and benefits mainly. However, certain limitations accompany two-dimensional radiographs, which can be definitively reduced, or there is less scope for technical error in three-dimensional imaging techniques. These are mainly cone-beam computed tomography, magnetic resonance imaging, and ultrasound (though cone-beam computed tomography is the most preferred by dentists in the maxillofacial region).

From simple intra-oral periapical X-rays to advanced imaging techniques like computed tomography, cone beam computed tomography, magnetic resonance imaging, and ultrasound have also been used, with CBCT being the most adopted technique in modern dentistry.

What Is the Difference Between Conventional and Digital Radiography?

In modern dentistry, the switching from analog to digital radiography has made dental radiography simpler and faster with additional benefits like image storage, manipulation (brightness and contrast or cropping of the obtained image), image retrieval software, etc.

The conventional or the long-time use of film-based radiography requires the presence and proper care or maintenance of the darkroom. Also, the chemical handling in the darkroom may be associated more often with processing or technical errors that depend upon the radiologist who is developing the X-ray.

Now the frequently used and preferred advent of digital radiography has overcome these disadvantages of development and fixation. This revolution in recent decades is the result of innovation by researchers and technicians alike for speeding up the image acquisition process. Also, the development of networked computing systems is beneficial and ideal for the dual purpose of image retrieval and image transmission.

Mainly there are three types of digital radiography systems used and commonly available for dental imaging, that include:

• CCD-Charge-Coupled Device (direct system).

• CMOS-Complementary Metal Oxide Semiconductor (direct system).

• PSP-Photo-Stimulable Phosphor (indirect system).

Why Is Digital Imaging Preferred Over the Conventional Imaging Techniques?

According to researchers, the advantage of digital radiography over conventional film radiography is that the radiation dose is almost reduced by up to 80 %. Given the apparent benefits of processing time within a short duration and the quick acquisition of the image post-radiography, it has been the most preferred way for more than a decade.

Also, the elimination of the darkroom and its processing chemicals for developing the film and fixation coupled with the technical errors, if any, by the operator, those errors associated with improper darkroom maintenance or mishandling of the chemical solutions is all avoided altogether by the digital imaging adopted in modern dental clinics and hospitals. Digital radiography also allows manipulation of the image produced to enhance contrast, density, sharpness, and image orientation. Also, the radiation exposure to the patient and the operator is much reduced.

What Are the Different Views in Dental Radiography?

1. Occlusal Radiographs: An occlusal radiograph displays a large segment of a dental arch that cannot be viewed on a periapical radiograph. It helps locate supernumerary or impacted teeth, any foreign bodies possibly in the jaw region, salivary stones (sialoliths), ductal stones of the salivary glands, and cysts.
2. Bitewing Radiographs: Also known as interproximal radiographs, they are commonly used to evaluate inter-proximal surfaces of the upper and lower teeth when the patient bites on the film. This is useful for diagnosing dental caries.
3. Extra-Oral Radiographic Views: The extra-oral radiographic examination in oral medicine includes the systematic study through panoramic radiographs, lateral skull view, Water’s view, the posteroanterior view, and lateral cephalometric view (based upon the indication by the dental surgeon). Extraoral radiographs will help the dentist precisely study the jaws and skull (especially the landmarks of importance). In addition, monitoring the growth and development of craniofacial structures skeletally, indicating the location of impacted wisdom teeth and large pathological lesions, and evaluating the temporomandibular joint make extraoral radiographic views an idealistic study.
4. Cephalometric Radiographs: It helps identify the entire side of the head and neck region and evaluate the spatial relationships between craniodental and craniofacial structures. This radiography is mainly valuable in comparing and contrasting growth and development in the dental and skeletal structures (done commonly by the orthodontist before, during, and after orthodontic treatment). The benefit is the correct acquisition of the patient’s soft tissue profile and lesser X-ray exposure compared to the other techniques.
5. Cone-Beam Computed Tomography: This is the most advanced and upgraded element of modern dentistry that dental clinicians prefer. This technique or method uses fan-shaped X-ray beams that produce multiple exposures around an object to reveal its internal structures in a three-dimensional view. These 3-D views of the object help the clinician view morphologic features and pathology. CBCT’s varied applications in all fields of dentistry include the detection of oral and maxillofacial or dental and developmental cysts, tumors, infections, anomalies, traumatic injuries, etc., in the orofacial region. Further, due to its high-resolution advantage, it is also extensively used for dental and osseous disease evaluation of the temporomandibular joints and treatment planning before placing dental implants by the dental implantologist.

Conclusion:

To conclude, the recent advances in imaging technologies have revolutionized dental diagnostics and treatment planning. Also, the correct use of newer radiographic techniques and the recent upgrades in technology can help detect dental and maxillofacial pathologies early and provide an excellent long-term prognosis for the patients affected.