The technology allowing for computer aided design / machining (CAD/CAM) of dental restorations such as crowns, porcelain veneers and onlays has been around for decades, but has only developed in recent years into a powerful and universally accessible tool. For example, the information about the size and shape of the required crown must pass from the patient’s mouth to the dental technician. The classic method commonly used to transfer such data is by using impression materials. A metal / plastic tray containing soft impression material is inserted into the patient’s mouth and allowed to set in it. This way, the shape of the teeth is embedded in the impression material. The impression is then sent to a dental laboratory, where the technician casts plaster in it, resulting in a work model allowing to fabricate the prosthetic restoration.
Over the years, ways have been sought to simplify this process, while producing a tool that will allow us to achieve things that using ordinary methods could not be achieved. This gave us the first dental scanner developed in the University of Zurich, which was later marketed by the German company Sirona.
How does the dental scanner work?
The scanner consists of two parts:
1. The scanner itself – a sophisticated optic camera that photographs the patient’s teeth quickly and at high resolution. The dentist passes over the patient’s teeth and the camera takes dozens of quick photographs.
2. Computer + software – the image set is assembled by the software to form a precise digital image of the patient’s mouth. The treated area may be immediately seen in a clear, magnified manner from every possible direction. If a problem is identified, it is possible to go back to the patient’s mouth, correct it immediately and repeat the scan. Everything is quick, accessible and convenient. After that, the software may be used for precise planning of the necessary restorative work, such as the crown, which would be perfectly fitted to the treated tooth and the other teeth in the mouth in terms of size, shape and occlusion. The information is then transferred digitally to the production unit.
Advantages of the scanner:
1. Impression materials are not used in the patient’s mouth! This will come as particularly good news for people who are very sensitive and have a strong gag reflex, but it is good for everyone. The scanning experience is simple and not burdensome.
2. Fast – a quick scan followed by a touch of a button sends the information digitally to the digital milling unit for fabrication. Saving of time and work stages that apply to conventional techniques.
3. High precision.
4. Esthetics – the information from the scanner is transferred digitally to the milling machine. In it, each restoration is created using advanced materials, such as zirconia, or reinforced porcelain, such as e.max. These restorations contain no metal at all and the result is that esthetic “all porcelain” crowns may be fabricated for any tooth, anterior or posterior.
5. The scanner may also be used for preliminary planning of dental implant placement. The combination of the information gathered by the scanner and CT imaging, and planning of a surgical guide for implantation, allows the precise placement of the implants and even preparation of the provisional restoration in advance.