Objectives The palatal scans of the same individuals were compared after two years
to assess forensic reproducibility. The effect of orthodontic treatment, the comparison
area and the digitization approach were investigated. Methods The palate was scanned
in 20 pairs of monozygotic twins by an intraoral scanner (IOS) three times to assess
repeatability. They were rescanned two years later by two different IOSs. An elastic
impression and a plaster model were also made and scanned by a laboratory scanner
(indirect digitization). Mean absolute distance between scans was compared after best-fit
alignment. Scans from the two sessions were compared to evaluate the combined effect
of aging, orthodontic treatment and different digitization methods (forensic reproducibility).
Additionally, the scans of different digitization methods from the second session
were compared (technical reproducibility). The between-siblings difference was compared
in the two sessions to evaluate the effect of aging on palatal morphology. Results
The anterior palatal area showed significantly better repeatability and forensic reproducibility
than the whole palate (p<0.001), but orthodontic treatment had no effect. Indirect
digitization produced lower forensic and technical reproducibility than IOSs. For
IOSs, repeatability (22 µm) was significantly (p<0.001) better than either forensic
(75-77 µm) or technical reproducibility (37 µm). No significant changes were observed
from the first to the second session in the between-sibling comparison. The closest
between-sibling value (239 µm) considerably exceeded the highest forensic reproducibility
value (141 µm). Conclusions Reproducibility is acceptable between the different IOSs,
even two years apart, but is poor between IOS and indirect digitization. The anterior
palate is relatively stable in young adults. Clinical Significance Intraoral scanning
of the anterior palatal area has superior reproducibility, regardless of the IOS brand.
Therefore, the IOS method could be suitable for identifying humans through anterior
palatal morphology. However, the digitization of elastic impressions or plaster models
had low reproducibility, preventing their application for forensic purposes.
