Digital impression technology is increasingly used in clinical practice as it is said to have many advantages above, and the potential to substitute for, conventional impression techniques.
Intraoral scanners use surface capturing technologies to acquire data. Scan bodies are captured by intraoral scanners and can be used to locate the implant positions in a virtual model.
The accurate transfer of implant positions in relation to neighboring implants or teeth is paramount for the design and the fit of implant-supported prosthesis.
Therefore, this systematic review has evaluated the scientific evidence for the accuracy of optical implant scans compared with scans of stone cast made from conventional implant impressions.
The term accuracy refers to trueness, describing the closeness of a measurement to the actual value, and to precision, describing the closeness of multiple measurement results (ISO 12836: 2015).
The present systematic review includes 79 studies consisting of one RCT, one retrospective study, two clinical studies, and 75 bench studies. A meta-analysis of 63 studies was performed after dividing the data into subgroups; however, a high heterogeneity of reported data was detected.
One of the reasons for the lack of clinical studies is related to the difficulty of assessing the trueness of intraoral impressions, as the actual implant positions can only be approximated as there is no control.
Currently, there is limited clinical evidence on the accuracy of intraoral digital impressions of dental implants compared with conventional implant impressions. The data were based on bench studies and one clinical study.
- The accuracy of digital impressions with intraoral scanners of single or adjacent implants in partially dentate jaws and multiple implants in edentulous jaws is comparable to the accuracy of conventional implant impressions under laboratory conditions.
Consensus statement 1 is based on six bench studies.
- The accuracy of digital impressions is negatively influenced with an increase in the interimplant span between multiple implants in partially dentate and edentulous situations.
Consensus statement 2 is based on three bench studies.
- The scan protocol using intraoral scanners has a significant influence on digital implant impression accuracy in the edentulous jaw.
Consensus statement 3 is based on four bench studies using the same control.
- The accuracy of digital implant impressions of edentulous jaws varies when using different intraoral scanners.
Consensus statement 4 is based on four bench studies.
- The use of digital impressions for single implant restorations can be recommended.
- To optimize digital implant impressions for each clinical situation, device-specific intraoral scanning protocols must be followed.
- The use of scan bodies is recommended for accurate digital implant impressions.
- Digital impressions of large interimplant spans are not yet recommended for routine clinical use.
- For routine clinical use, intraoral digital implant impressions of edentulous jaws cannot yet be recommended.