The Accuracy of Intraoral Scanning Systems for Full-Arch Impressions Is Examined in 10 Participants

In summary, this study intends to address the need for comprehensive in vivo research on the accuracy of intraoral impression methods, especially in the context of modern digital technologies. By comparing various digital and conventional methods, this research will offer valuable information to guide dental practitioners in choosing the most precise and reliable techniques for their clinical applications.

The following study design is planned:

The study is non-randomised. The study setup is monocentric. At the beginning of the session, 3 conventional impression each of the upper and lower jaw is taken. After 8 hours the impression is moulded by a dental technician with a SuperHard plaster (type 4).After 48 hours of setting time the plaster-model is scanned with a lab scanner (inEos X5, Dentsply Sirona) to generate a .stl-file that is comparable to the following digital impressions.

This is followed by 6 digital impressions of the upper and lower jaw and the associated bite registration in habitual occlusion, divided between two experienced practitioners (3 upper, 3 lower jaw scans, 3 bite registrations per practitioner) with the 8 different intra oral scanners. In total, 6 conventional (3 upper, 3 lower jaw impressions), 48 digital impressions and 48 bite registration are taken. If it is not possible to take all the impressions in one session, a new conventional impression is taken at the start of each new session, so that a daily updated reference model is always available. Minimizing bias is achieved, by using the intra oral scanners according to the manufacturers instructions.

The number of scans was calculated as part of a power analysis based on previous study results and should therefore be meaningful.

The selection of scanners represents a heterogeneous selection of devices currently on the market. The scanners come from different price categories and use different optical measuring principles.

The precision measurement is carried out by comparing the impressions within and between the tested groups (precision and trueness respectively). For that, the scans will be exported to STL & PLY format (depending on the scanning device) and imported into evaluation programs (Dentexion, Dentexion and Control X, Geomagic). The evaluation process follows the ISO 5725-1 criteria. After superimposition of the mesh surfaces according to the best-fit alignment, the distances will be measured point-to-point using the signed nearest neighbor method and sorted into a histogram. From that, the distance measure for each pairwise surface superimposition will be calculated from the (90%-10%)/2 percentile value.

Inclusion criteria

• All genders, minimum age for participation is 18 years
• Good general health and healthy dental conditions (gaps with a maximum of 1 missing tooth are permitted)
• Written consent after informed consent discussion is available

Exclusion criteria

• participants under the age of 18
• Addicts or participants with impaired cognitive abilities that do not allow the participant to assess the scope of the study
• participants suffering from periodontitis (pathological tooth mobility could falsify the study results)
• Maximal mouth opening less than 3.5 cm
• participants who wear large reconstructive works and/or have a free-end situation from at least the 2nd premolar