Trueness and precision of combined healing abutment-scan body system depending on the scan pattern and implant location: an in-vitro study
Citation
Donmez MB, Çakmak G, Atalay S, Yilmaz H, Yilmaz B. Trueness and precision of combined healing abutment-scan body system depending on the scan pattern and implant location: an in-vitro study. J Dent. 2022 Jun 1:104169. doi: 10.1016/j.jdent.2022.104169. Epub ahead of print. PMID: 35661761.Abstract
Objective: To test the effect of scan pattern and the location of the implant on the trueness and
precision of implant scans when the combined healing abutment-scan body (CHA-SB) system is
used.
Material and Methods: A partially edentulous maxillary model with CHA-SBs secured on
implants at 3 different sites in the left quadrant (central incisor, first premolar, and first molar)
was fabricated. The model was scanned with an industrial light scanner to generate a master
reference model (MRM) file. An intraoral scanner (TRIOS 3) was used to perform the test scans
(n=8) with 4 different scan patterns (SP1, SP2, SP3, and SP4) with an intraoral scanner. The test
scans were superimposed over the MRM file with a metrology software to calculate the distance
deviations of the CHA-SB system. Data were analyzed with a 2-way analysis of variance and
Tukey’s honestly significant difference tests for accuracy (α=.05).
Results: Trueness (P=.001) and precision (P=.018) were significantly affected by the interaction
between the scan pattern and implant location. The implant located at the central incisor site (56.7
±35.9, 36.2 ±18.6) had higher trueness than that of located at the premolar site (94.1 ±20.4, 100.3
±20) when SP2 (P=.037) and SP4 (P=.002) were used. The implant at the molar site (71.9 ±25.7,
147.2 ±49.7) had trueness either similar to (when SP2 was used, P≥.276) or lower than (when
SP4 was used, P≤.024) those of others. Scans of the central incisor and premolar implants had the
lowest trueness when scanned with SP1 (P≤.009), while the scans of molar implant showed
higher trueness when performed by using SP2 and SP3 when compared with SP4 (P≤.005).
When SP4 was used, the implant at the molar site had lower precision (43 ±18.9) than the
implants located at the central incisor (14.1 ±11) and premolar sites (15.4 ±11.3) (P=.002). Scan
patterns affected the scan precision of central incisor implant (P=.009), as SP4 (14.1 ±11) led to a
higher precision than SP1 (47.7 ±27) (P=.006).
Conclusions: The scan accuracy of combined healing abutment-scan body system was affected
by scan pattern and implant location. SP1, which involved palatal and rotational scans resulted in
the lowest trueness for central incisor and premolar implants, while the scans of the central
incisor implant showed the highest trueness among different sites when SP4 was used. However,
the scan pattern and implant site had a minor effect on precision. Scan precision at different
implant sites only differed when SP4 was used, which resulted in the lowest precision for molar
implant.
Clinical Significance
Rotational scanning of the palate after linear scanning of complete arch did not have any
additional benefit for accuracy. In addition, rotational movements could impair the scan accuracy
at the molar site.