Effect of implant depth on accuracy: a comparative study using intraoral scanner and photogrammetry systems

This study aimed to evaluate the influence of implant placement depth on the accuracy of five full-arch digital impression techniques: 2 photogrammetry systems (Imetric [PGI] and Oxo Core [PGO]) and 3 intraoral scanning (IOS) routes (standard IOS, IOS with crown-shaped [IOS+C], and IOS with laterally-extending [IOS+LE] scanning aids).

Three master models including 5 implants with 2-, 4-, and 6-mm subgingival implant depths were fabricated. Implant positions were recorded using each of the 5 techniques (n = 15). The resultant scans were compared to reference data generated by a laboratory scanner. Deviations were 3-dimensionally assessed using root mean square values to quantify both trueness and precision. Angular deviations (AD) were calculated to provide a detailed assessment of spatial inconsistencies. Data were statistically analyzed (α = 0.05).

Implant depth and impression technique, as well as their interaction, significantly affected trueness, precision, and angular deviation values (P < .001). PGI demonstrated the highest accuracy, with the lowest mean AD values across all implant positions (0.24 - 0.32°) and the highest trueness (26.57 µm) and precision (7.72 µm). IOS exhibited the largest distortions, with AD values up to 1.77° and trueness values of 74.84 µm. Precision of both photogrammetry systems were not influenced by implant depth.

Implant depth significantly impacts the accuracy metrics of full-arch digital impressions. The Imetric system outperformed the other groups. Since laterally-extending scanning aids effectively improved accuracy, it may be recommended as a clinically viable alternative to standard IOS.