Choosing the Right Dental Radiography System

There are four main types of dental radiography systems: dental X-ray generators, panoramic X-ray systems, cephalometric X-ray systems, and CBCT scanners.

• Dental X-ray generators: Dental X-ray generators can take X-rays of one or more teeth. There are different types of radiographs or X-rays:
  • Bitewing X-rays: Very common and usually carried out as a preventive examination. They can be used to identify decay between teeth or below the gum line, as well as the source of potential dental discomfort.
  • Periapical X-rays: Periapical radiographs allow you to take a radiograph of the whole tooth (and not just part of it, as with Bitewing radiographs), and go even slightly beyond the root of the tooth. This type of X-ray is used when a problem is suspected at the tooth’s root tip or in the jawbone.
  • Occlusal X-rays: Occlusal radiographs allow us to view a small group of teeth. This allows the dentist to see the full development and position of the teeth, to understand why certain teeth have not yet erupted, or to identify supernumerary teeth. Cysts, abscesses, cleft palates, or fractures can also be detected with this type of X-ray.

• Panoramic X-ray systems: Panoramic X-rays take a 2D image of the entire dentition (front view).
• Cephalometric X-ray systems: Cephalometric X-rays take a 2D image of one side of the entire head (lateral view).
• CBCT (or Cone Beam) scanners: CBCT scanners take digital images of bone structures and three-dimensional reconstructions. Depending on the model, the device can capture a larger or smaller volume of the teeth and surrounding bones. It should be noted that this device uses a much lower dose of radiation than conventional CT scans, which use a fan-shaped radiation beam, also known as a ‘fan-beam’.

Nowadays, there is a lot of hybrid equipment, capable of carrying out more than one type of extraoral radiography:

• panoramic and cephalometric
• panoramic and CBCT
• panoramic, cephalometric, and CBCT

Acteon panoramic + cephalometric + CBCT system

There are several features to consider when choosing a dental generator, such as size and configuration, power, and collimator size.

• Size and configuration: Depending on the space available in the office, there are three different sizes and configurations to choose from:
  • Wall-mounted X-ray machines: With these machines, it’s important to check the arm lengths.
  • X-ray machines on wheels: A seat can sometimes also be integrated.
  • Portable X-ray machines: It’s important to know their weight.

• Power: The device’s power determines the type of image possible (digital, analog, or both) and the exposure time required. Dental X-ray generators have a high power – between 30 kW and 100 kW – to generate images quickly. The average power used is between 50 kW and 70 kW.

• Collimator size and adjustability: The collimator limits the size of the X-ray field of incidence and the maximum image size generated.

KaVo Dental wall-mounted dental X-ray generator

Intraoral X-ray devices are the most economical solution for dental X-rays because they are compact and the examination is very quick. However, their use remains limited to only certain applications. It is better to use a sensor with an intraoral radiography device, particularly one that works with lower radiation doses, such as CMOS digital intraoral sensors. CMOS sensors have advantages over flexible photostimulable phosphor plate-type image receptors, including:

• Greater durability and resistance compared to flexible sensors
• (Almost) immediate visualization of the image on the screen
• Reduced exposure time and therefore the radiation dose absorbed by the patient
• Reasonable maintenance costs
• Ease of sterilization

However, the following characteristics of these sensors should also be taken into account:

• Maximum possible resolution
• Sensor size, which should be sufficient for radiographing large teeth (at least 22 mm)
• Degree of water resistance (IPx7 rating recommended)
• Connection type (preferably USB)
• Compatibility of the supplied software with existing equipment

Intraoral DR sensor with CMOS technology from Simple&Smart

Although it is the most expensive dental imaging device, a cone beam computed tomography scanner is necessary in several situations, particularly whenever a 3D image is required to establish a precise diagnosis or to carry out specific assessments. These are the main cases in which a CBCT scanner is used:

• More information needed for diagnosis: Sometimes, when 2D radiology (panoramic) doesn’t provide enough information for a diagnosis or to prescribe a treatment, a 3D image is essential, and CBCT scanning is used.
• Pre-surgical periapical assessment: CBCT is recommended for pre-surgical periapical assessments, particularly in the posterior region of the jaw or in the mental foramen.
• Root pathology assessments
• Additional root canal: CBCT scans are used to search for and locate an additional root canal.
• Pre-implant assessment: CBCT scans are used for pre-implant assessments, in particular, to assess whether the bone volume is sufficient to receive the implant.
• Assessment of the extent of tumor lesions in the jaws.
• Study of maxillary sinuses and nasal cavities.

Planmeca dental CBCT scanner

CBCT scanners can be categorized according to the size of their field of view (FOV). The size of the FOV will make it possible to acquire larger or smaller volumes and is therefore a key criterion for choosing a CBCT scanner. The following CBCT scanners are available:

• Small field: Less than 10 cm
• Medium field: Between 10 and 15 cm
• Large field: Greater than 15 cm

Another important parameter to consider when choosing a CBCT scanner is the voxel size, which defines the resolution of the 3D image.

A device that uses a very small voxel (0.076 mm) generates very detailed images, making it possible to observe minute changes in anatomical structures. In other words, the larger the voxel size, the lower the resolution of the image and, consequently, the more difficult it is to distinguish between nearby small structures.

Most CBCT scanners have voxels of 0.2 mm, 0.3 mm, or 0.4 mm. The size of the voxel you use will depend on the object of study and the degree of detail you need the images to show.

In certain cases, it is preferable to opt for an isotropic voxel (the sides of the voxel are the same size), which makes it possible to take reliable measurements of the various anatomical structures analyzed.