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. 2026 Jan;87(1):83-90.
doi: 10.1007/s00056-024-00558-7. Epub 2024 Oct 24.

Tooth segmentation by low-dose CBCT for orthodontic treatment planning : Explorative ex vivo validation

Maurice Ruetters  1 , Holger Gehrig  2 , Sinclair Awounvo  3 , Ti-Sun Kim  2 , Sara Doll  4 , Korallia Alexandrou  5 , Anna Felten  2 , Christopher Lux  5 , Sinan Sen  6
Affiliations

Tooth segmentation by low-dose CBCT for orthodontic treatment planning : Explorative ex vivo validation

Maurice Ruetters et al. J Orofac Orthop. 2026 Jan.

Abstract
in English, German

Purpose: Three-dimensional imaging has become an increasingly important component of orthodontics. Associated with this, however, is a higher radiation exposure for patients. New cone-beam computed tomography (CBCT) devices have been developed that can provide low-dose CBCT (LD-CBCT). We hypothesized that LD-CBCT is as precise and reproducible as standard high-dose CBCT (HD-CBCT) in segmenting roots and crowns as well as measuring tooth length.

Methods: HD-CBCT and LD-CBCT scans were taken of four human cadaveric heads. Thirty single-rooted teeth were segmented twice by one investigator. The length of each tooth was also measured. Lin's concordance correlation coefficient (CCC) was calculated to assess the agreement of HD-CBCT and LD-CBCT measurements and the intraclass correlation coefficient (ICC) was calculated to assess intrarater reliability. Analyses were supported by Bland-Altman plots.

Results: Volume measurements obtained using HD-CBCT were significantly higher than those obtained using LD-CBCT (p < 0.001). CCC was 0.975 (95% confidence interval [CI] = 0.956-0.986) indicating excellent agreement between the two modalities. Intrarater reliability between the two sets of LD-CBCT and HD-CBCT volume measurements was excellent (ICC = 0.998, 95%CI = 0.995-0.999 [HD-CBCT], ICC = 0.997, 95%CI = 0.992-0.998 [LD-CBCT]). CCC for tooth length measurements was 0.991 (95% CI = 0.983-0.995), indicating excellent agreement between HD-CBCT and LD-CBCT. Intrarater reliabilities between the two sets of tooth length measurements were also excellent for both methods (ICC = 0.998, 95%CI = 0.995-0.999 [HD-CBCT], ICC = 0.997, 95%CI = 0.992-0.998 [LD-CBCT]).

Conclusions: Within the limitations of this experimental setting, LD-CBCT is as valid as HD-CBCT for measuring tooth length. Regarding the volume differences, in vivo studies are required to determine their clinical relevance.

Zusammenfassung: ZIELSETZUNG: Dreidimensionale Bildgebung ist zu einem immer wichtigeren Bestandteil der Kieferorthopädie geworden. Damit verbunden ist jedoch eine höhere Strahlenbelastung für Patienten. Neu entwickelte Geräte für die digitale Volumentomographie („cone-beam computed tomography“, CBCT) ermöglichen Tomographien mit reduzierter Strahlenbelastung („low dose cone-beam computed tomography“, LD-CBCT). Wir stellten die Hypothese auf, dass die LD-CBCT bei der Segmentierung von Zahnwurzeln und -kronen sowie bei der Messung von Zahnlängen genauso präzise und reproduzierbar ist wie die konventionelle HD-CBCT mit hoher Strahlendosis.

Methode: Von 4 Köpfen menschlicher Leichen wurden HD-CBCT- und LD-CBCT-Scans angefertigt. 30 Zähne mit einer Wurzel wurden von einem Untersucher zweimal segmentiert. Die Länge jedes Zahns wurde ebenfalls gemessen. Der Konkordanz-Korrelationskoeffizient (CCC) nach Lin wurde berechnet, um die Übereinstimmung von HD-CBCT- und LD-CBCT-Messungen zu ermitteln. Zur Bewertung der Intrarater-Reliabilität wurde der Intraklassen-Korrelationskoeffizient (ICC) berechnet. Die Analysen wurden durch Bland-Altman-Diagramme bestätigt.

Ergebnisse: Die mit HD-CBCT ermittelten Volumenmessungen waren signifikant höher als die mit LD-CBCT ermittelten (p < 0,001). Der CCC betrug 0,975 (95 %-Konfidenzintervall [KI] = 0,956–0,986), was auf eine hervorragende Übereinstimmung zwischen beiden Modalitäten hinweist. Die Intrarater-Reliabilität zwischen den beiden Sätzen von LD-CBCT- und HD-CBCT-Volumenmessungen war ausgezeichnet (ICC = 0,998, 95 %-KI = 0,995–0,999 [HD-CBCT], ICC = 0,997, 95 %-KI = 0,992–0,998 [LD-CBCT]). Die CCC für Zahnlängenmessungen betrug 0,991 (95 %-KI = 0,983–0,995), was auf eine hervorragende Übereinstimmung zwischen HD-CBCT und LD-CBCT hinweist. Auch die Intrarater-Reliabilität zwischen den beiden Messreihen der Zahnlänge war bei beiden Methoden ausgezeichnet (ICC = 0,998, 95 %-KI = 0,995–0,999 [HD-CBCT], ICC = 0,997, 95 %-KI = 0,992–0,998 [LD-CBCT]).

Schlussfolgerungen: Innerhalb der Grenzen dieser experimentellen Anordnung ist LD-CBCT für die Messung der Zahnlänge genauso aussagekräftig wie HD-CBCT. Hinsichtlich der Volumenunterschiede sind In-vivo-Studien erforderlich, um ihre klinische Relevanz zu bestimmen.

Keywords: Low-dose cone-beam computed tomography; Radiation exposure; Three-dimensional imaging; Tooth length; Tooth volume.

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Conflict of interest statement

Declarations. Conflict of interest: M. Ruetters, H. Gehrig, S. Awounvo, T.-S. Kim, S. Doll, K. Alexandrou, A. Felten, C. Lux and S. Sen declare that they have no competing interests. Ethical standards: All procedures involving human participants were in accordance with the ethical standards of the institutional and national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. The study was approved by the ethical review board of the University of Heidelberg, Germany (S-017/2020) and by the ethical review board of the medical association of Rhineland–Palatinate (Germany) (2021-15661). Informed consent was not required for this study, because human donors have already given their consent prior to donation of their body to the Department of Anatomy and Cell Biology of the University of Heidelberg for research.

Figures

Fig. 1
Fig. 1
Flowchart of tooth volume (a–c) and tooth length (d) measurements. a Axial high-dose cone-beam computed tomography (HD-CBCT) slice, b segmentation of tooth 31 in the axial HD-CBCT slice, c three-dimensional model of the tooth after segmentation, d measurement of tooth length (L) Flowchart der Messungen von Zahnvolumen (a–c) und Zahnlänge (d). a Axiale Schichtaufnahme, high-dose digitale Volumentomographie (HD-CBCT), b Segmentierung von Zahn 31 in der axialen HD-CBCT-Schicht, c dreidimensionales Modell des Zahns nach der Segmentierung, d Messung der Zahnlänge (L)
Fig. 2
Fig. 2
Bland–Altman plots of low-dose (LD-CBCT) and high-dose cone-beam computed tomography (HD-CBCT) volume measurements (mm3) from a the first round of measurements and b the second round of measurements Bland-Altman-Plots der Zahnvolumenmessungen (mm3) mit der dosisreduzierten (LD-CBCT) und der high-dose digitalen Volumentomographie (HD-CBCT) a aus der ersten und b aus der zweiten Messrunde
Fig. 3
Fig. 3
Bland–Altman plots of low-dose (LD-CBDT) and high-dose cone-beam computed tomography (HD-CBCT) tooth length measurements (mm) from a the first round of measurements and b the second round of measurements Bland-Altman-Plots der Zahnlängenmessungen (mm) mit der dosisreduzierten (LD-) und der high-dose digitalen Volumentomographie (HD-CBCT) a aus der ersten und b aus der zweiten Messrunde
See this image and copyright information in PMC

References

    1. Ruetters M, Gehrig H, Kronsteiner D et al (2022) Low-dose CBCT imaging of alveolar buccal bone adjacent to mandibular anterior teeth—a pilot study. Clin Oral Investig 1: - PMC - PubMed
    1. Ruetters M, Gehrig H, Kronsteiner D et al (2022) Ex-vivo imaging of buccal and oral periodontal bone with low-dose CBCT in porcine jaws. Dentomaxillofac Radiol 51(1):20210233 - DOI - PMC - PubMed
    1. Patcas R, Markic G, Muller L et al (2012) Accuracy of linear intraoral measurements using cone beam CT and multidetector CT: a tale of two CTs. Dentomaxillofac Radiol 41(8):637–644 - DOI - PMC - PubMed
    1. Lee RJ, Ko J, Park J et al (2019) Accuracy and reliability of the expected root position setup on clinical decision making of root position at midtreatment. Am J Orthod Dentofacial Orthop 156(4):566–573 - DOI - PubMed
    1. Lee RJ, Pi S, Park J et al (2018) Accuracy and reliability of the expected root position setup methodology to evaluate root position during orthodontic treatment. Am J Orthod Dentofacial Orthop 154(4):583–595 - DOI - PubMed

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