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Measurements using orthodontic analysis software on digital models obtained by 3D scans of plaster casts

Intrarater reliability and validity

Virtuelle Modellvermessung mit einer kieferorthopädischen Analysesoftware nach 3-D-Scan von Gipsmodellen

Intrarater-Reliabilität und Validität

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Journal of Orofacial Orthopedics / Fortschritte der Kieferorthopädie Aims and scope Submit manuscript

Abstract

Objective

The purpose of this work was to determine the reliability and validity of measurements performed on digital models with a desktop scanner and analysis software in comparison with measurements performed manually on conventional plaster casts.

Materials and methods

A total of 20 pairs of plaster casts reflecting the intraoral conditions of 20 fully dentate individuals were digitized using a three-dimensional scanner (D700; 3Shape). A series of defined parameters were measured both on the resultant digital models with analysis software (Ortho Analyzer; 3Shape) and on the original plaster casts with a digital caliper (Digimatic CD-15DCX; Mitutoyo). Both measurement series were repeated twice and analyzed for intrarater reliability based on intraclass correlation coefficients (ICCs). The results from the digital models were evaluated for their validity against the casts by calculating mean-value differences and associated 95 % limits of agreement (Bland–Altman method). Statistically significant differences were identified via a paired t test.

Results

Significant differences were obtained for 16 of 24 tooth-width measurements, for 2 of 5 sites of contact-point displacement in the mandibular anterior segment, for overbite, for maxillary intermolar distance, for Little’s irregularity index, and for the summation indices of maxillary and mandibular incisor width. Overall, however, both the mean differences between the results obtained on the digital models versus on the plaster casts and the dispersion ranges associated with these differences suggest that the deviations incurred by the digital measuring technique are not clinically significant.

Conclusion

Digital models are adequately reproducible and valid to be employed for routine measurements in orthodontic practice.

Zusammenfassung

Ziel

Ziel der vorliegenden Studie war die Bestimmung der Reliabilität und Validität eines Systems aus Desktopscanner und Analysesoftware im Vergleich zum konventionellen Gipsmodell.

Material und Methoden

20 Gipsmodellpaare von vollbezahnten Probanden wurden mit einem Desktopscanner (D700, 3Shape) digitalisiert. Die Vermessung erfolgte mit einer Analysesoftware (Ortho Analyzer, 3Shape). Alle Messungen wurden analog an denselben Gipsmodellen mit einem digitalen Messschieber (Digimatic CD-15DCX, Mitutoyo) durchgeführt und sowohl analog als auch digital zweimal wiederholt. Die Reliabilität der einzelnen Variablen wurde mit dem Intraclass Correlation Coefficient (ICC) ermittelt. Die Validität wurde durch die Differenzen der Mittelwerte sowie deren 95%igen Konfidenzintervallen (Bland-Altman-Plot) dargestellt. Ein gepaarter T-Test wurde durchgeführt.

Ergebnisse

Es lagen statistisch signifikante Unterschiede für 16 von 24 Zahnbreitenmessungen, für 2 Kontaktpunktverlagerungen im Unterkieferfrontzahnbereich, für den Overbite, für die intermolare Distanz, für den Little-Index sowie für die Summenindizes der Ober- und Unterkieferschneidezähne vor. Das Ausmaß der mittleren Differenzen zwischen analoger und digitaler Messung, sowie das Ausmaß der Streuung der Abweichungen, deuten jedoch auf klinisch nicht signifikante Abweichungen zwischen den Messmethoden hin.

Schlussfolgerung

Digitale Modelle sind für routinemäßige Messungen in der Kieferorthopädie ausreichend reproduzierbar und valide.

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Authors and Affiliations

  1. Department of Orthodontics, Martin Luther University, Große Steinstrasse 19, 06108, Halle (Saale), Germany

    Judith Czarnota & Robert Fuhrmann

  2. Department of Prosthodontics, Martin Luther University, Große Steinstrasse 19, 06108, Halle (Saale), Germany

    Jeremias Hey

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  1. Judith Czarnota
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  2. Jeremias Hey
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  3. Robert Fuhrmann
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Correspondence to Judith Czarnota.

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On behalf of all authors, the corresponding author states that there are no conflicts of interest. Informed consent was obtained from all patients included in studies.

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Czarnota, J., Hey, J. & Fuhrmann, R. Measurements using orthodontic analysis software on digital models obtained by 3D scans of plaster casts. J Orofac Orthop 77, 22–30 (2016). https://doi.org/10.1007/s00056-015-0004-2

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  • DOI: https://doi.org/10.1007/s00056-015-0004-2

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