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Impact of scan body geometry and library file modifications on matching between intraoral implant scans and library
Dong-Hun Lee1, Koungjin Park2, Carme Riera3
1Graduate student, Department of Integrated Dentistry, Seoul National University School of Dentistry, Seoul, Republic of Korea.
Statement Of Problem:
It remains unclear whether trimming sharp edges from scan body library files improves automatching accuracy, what magnitude of trimming is optimal, and whether any benefits are consistent across different scan body geometries.
Purpose:
The purpose of this in vitro study was to evaluate the effect of scan body geometry and the edge trimming of scan body library files on the accuracy of matching between intraoral scans and library files.
Material And Methods:
Two scan body geometries (angular and rounded) were evaluated with 3 library file designs: unmodified (U), 0.1-mm edge removal (E01), and 0.3-mm edge removal (E03). Ten scan bodies per geometry were scanned using a desktop scanner and an intraoral scanner. Library files were matched to the intraoral scan data in a computer-aided design software program to generate implant positions that were compared with reference positions derived from desktop scans. Deviations were measured as the linear distance between implant apices, angular difference between long axes, and root mean square surface deviation (n=10 per group). The data were analyzed by using mixed 2-way analysis of variance (α=.05).
Results:
Edge trimming improved accuracy. For the angular geometry, linear deviation decreased from 118.4 ±21.7 µm (U) to 93.6 ±20.9 µm (E03; P=.001), angular deviation decreased from 0.33 ±0.12 degrees (U) to 0.24 ±0.11 degrees (E03; P=.043), and surface deviation decreased from 56.4 ±4.8 µm (U) to 44.0 ±6.9 µm (E03; P<.001). For the rounded geometry, linear deviation decreased from 91.2 ±12.1 µm (U) to 73.6 ±11.0 µm (E03; P=.020), and surface deviation decreased from 51.7 ±4.9 µm (U) to 39.1 ±5.1 µm (E03; P<.001). The rounded scan body showed lower linear deviation than the angular across all library designs (all P<.05).
Conclusions:
Edge removal in library files and the use of simpler rounded scan body geometry enhanced the accuracy of library automatching between intraoral implant scans and scan body library files.