How does an Oral Scan Work?

Intraoral digital impression technology has a history of nearly 40 years. As early as 1980, Dr. Werner Mormann of Switzerland and engineer Marco Brandestini of Italy cooperated to develop intraoral scanning technology.

In 1987, Sirona launched the first generation of dental restoration CAD/CAM system, CEREC I, and successfully released the world's first commercial intraoral 3D scanner.

iTero was developed and marketed by Cadent (Israel) in 2007.

Trios system 3Shape (Denmark) developed the Trios system in 2010 and put it on the market in 2011.

Up to now, in addition to the previous major intraoral digital impression systems, there is also the LavaC.O.S system of 3M company, the DWIO system of Canada, our domestic Langcheng system, and some other brands.

There are three main working principles of intraoral digital impression technology, namely confocal microscopy imaging technology, triangulation technology, and active wavefront sampling technology. The iTero brand of intraoral scanners uses confocal microscopy imaging technology. The CEREC intraoral scanning system is a typical application of triangulation technology. The Lava C.O.S. (3M, USA) intraoral scanner is an existing system using active wavefront sampling technology

Strengths and limitations

Compared with traditional impression techniques, intraoral digital impressions also have the following advantages:

Standard impression technology requires clinical impression making and plaster model reproduction to obtain dental and jaw information. These steps may cause operational errors. The intraoral digital impression technology can simplify the process into one step. The error of the digital impression only comes from the scanning error, and the controllability of the source of the error is greatly improved;

The intraoral digital impression can obtain the color information of the oral soft and hard tissues and realize true color scanning;

Chairside digital restoration can be achieved through intraoral digital scanning, reducing patient waiting time. Improve patient satisfaction;

Some patients with severe gag reflex are unacceptable for the impression-taking materials used in traditional impression techniques, while digital intraoral scanning can effectively improve the comfort of patients;

During intraoral scanning, the doctor can observe the dental preparation in the mouth in real-time, which is convenient for timely adjustment and more flexible.

However, limited by the current technological development, intraoral digital impression technology also has certain limitations. Mainly in the following aspects.

•  For edentulous jaws lacking obvious anatomical features, it is difficult to obtain digital impressions and the scanning accuracy is low;

  
  

• Temporarily unavailable; dynamic functional occlusion information.

  Clinical application

At present, intraoral digital impression technology has been widely used in clinical practice, including the following aspects:

Chairside digital restoration: CEREC system is a typical chairside digital restoration system. After the dental preparation data in the patient’s mouth is quickly obtained by intraoral scanning, the conventional restoration design is carried out immediately. The cutting and manufacturing of the restoration can be completed within 20-30min.

Digital Orthodontics: The I Tero intraoral scanner is compatible with the Invisalign invisible aligner system, omitting the complicated procedures of traditional reproduction and mailing of impressions, realizing an efficient and convenient invisible appliance design and production process.

Digital implant design: 3shape implant design software can integrate with patient CT after importing oral scan files, design a digital implant surgery plan, and design corresponding digital surgical guides

3shape Trios intraoral scan

Before performing an intraoral scan, the items required for the scan should be prepared. In addition to the standing instruments for an oral examination, the scanning head and calibration equipment are also required. 

First, install the 3D calibration head on the scanning gun, and click on the scanner to set the scanning 3D calibration scanner to perform 3D calibration. Intraoral scanners are 3D calibrated once a day.

Then install the tooth color calibration head and the calibration block on the scanner gun, touch the scanner to set the scanning tooth color measurement color calibration and follow the on-screen prompts to perform tooth color calibration. Intraoral scanners are calibrated weekly

1. Install a sterilized scanning head on the scanning gun, tap Add Patient on the scanner, and enter patient and doctor information. Click to add a case, select the processing factory, the corresponding tooth position, and restoration. If considered as a hosted model, you can choose to tap Selected Study Model.

2. The patient's position can be selected at 45°, the intraoral scanner is placed on the left back of the patient, and the doctor stands on the right back of the patient to perform the scanning operation.

3. The saliva on the patient's teeth will affect the accuracy and speed of scanning, so wipe the teeth with a dry cotton ball before scanning, and then dry the teeth with an air gun.

4. When scanning, follow the instructions to scan the occlusal surface first, then the lingual and buccal surfaces, and finally, fill in the gaps in the scan.

5. When scanning the lower jaw, the scanning head is facing down, and when scanning the upper jaw, the scanning head can be removed and turned upside down, and installed on the scanning gun for scanning.

6. After each scanning, the scan pattern needs to be trimmed to remove unnecessary soft tissue patterns.

7. After scanning the upper and lower jaws, start to scan and record the patient's bilateral occlusion to ensure that the patient's occlusion is stable and consistent.

8. After the occlusal scan is completed, check the image on the scanner.

9. After checking, the order can be sent to the corresponding processing plant.