Digital Dentistry

Digital dentistry means using computer-assisted methods for examination, impressions, planning and some stages of manufacturing. It is not a treatment in itself but a set of tools that help plan and carry out treatments better.

For patients, three main things change:

• More can be seen. With a 3D CT scan, bone, nerves, sinuses and impacted teeth are examined in detail that an X-ray cannot show.
• Impressions are more comfortable. An intraoral scanner takes a 3D record of the teeth, in most cases without impression trays and paste.
• The plan can be seen in advance. The position of an implant, the movement of the jaws or a new smile is planned on screen before treatment and explained to you.

A dental cone beam CT scan (CBCT) images the jaws and teeth in three dimensions. While a panoramic X-ray gives an image in a single plane, a CT scan makes it possible to examine the same area from different angles and in cross-sections, and to take measurements to the millimetre.

The scan is usually taken standing or sitting, is quick and painless. The radiation dose is much lower than with the medical CT scanners used in hospitals. Even so, it is not taken routinely for every patient, but only when needed and for the smallest area necessary. If there is any chance you may be pregnant, you must say so before the scan.

Main uses:

• Measuring bone height, width and density before implants
• Locating structures such as nerves and the sinuses
• Assessing the position of impacted teeth and their closeness to the nerve
• Examining the size of cysts, tumours and infections and their relationship with neighbouring structures
• Assessing the bone of the jaw joint
• Assessing jaw and facial asymmetry and planning before orthognathic surgery
• Detailed assessment of bone loss around teeth

An intraoral scanner creates a 3D digital model by scanning the teeth and gums with a pen-sized camera. In most cases the tray and paste used for conventional impressions are not needed; this is especially comfortable for patients with a strong gag reflex.

The scanned model appears on the computer immediately, and if an area is missing, only that area is rescanned. The record can be sent digitally to the laboratory and is kept on file, so changes over time can be compared. For very large toothless areas or some special prostheses, conventional impressions may still be preferred.

When the CT scan, the intraoral scan and facial photographs are combined on a computer, a detailed plan can be made before treatment starts:

• Implant planning: The length, diameter, angle and depth of the implant are planned with the future tooth in mind (see Guided Implant Surgery).
• Smile design: The shape and length of the teeth are designed on facial photographs; the design can be tried in the mouth (see Smile Design).
• Orthognathic surgery: How far the jaws will be moved is planned virtually, and custom surgical splints are produced from this plan (see Orthognathic Surgery).

Seeing the plan on screen also makes the conversation between doctor and patient easier: what will be done, why it will be done that way and the likely result are reviewed together.

Two methods are used to carry out the plan accurately during surgery:

• Surgical guide: A custom plate produced on a 3D printer from the plan, which fits in the mouth. It helps the drills and the implant follow the planned direction.
• Dynamic navigation: No plate is used in the mouth; special cameras track the position of the drill in real time and the surgeon works while seeing the drill's position against the planned path on a screen.

Neither method replaces the surgeon; both are tools that help carry the plan into surgery. Details are on the Guided Implant Surgery page.

Digitally designed restorations such as crowns, bridges, porcelain inlays and veneers can be produced with computer-controlled milling or 3D printers. This reduces the transfer steps between design and production and can shorten the time for some restorations. Whether production is done in the clinic or in a laboratory depends on the type of restoration.

• Technology does not replace an examination. Images and plans only make sense together with a clinical examination and the doctor's assessment.
• Images are not flawless. Metal fillings and crowns can cause distortion on CT scans; moving blurs the record.
• Plans and guides can also deviate by fractions of a millimetre. This is why a safety margin is left from important structures during planning.
• The radiation is low but not zero. CT scans are only taken when needed.
• An on-screen simulation is a goal, not a guarantee of the final result.