Korean J Orthod.  2019 Jan;49(1):32-40. 10.4041/kjod.2019.49.1.32.

Benefits of lateral cephalogram during landmark identification on posteroanterior cephalograms

• Hwang SA
• Lee JS
• Hwang HS
• Lee KM

• KMID: 2431078
• DOI: http://doi.org/10.4041/kjod.2019.49.1.32

Abstract

OBJECTIVE
Precise identification of landmarks on posteroanterior (PA) cephalograms is necessary when evaluating lateral problems such as facial asymmetry. The aim of the present study was to investigate whether the use of lateral (LA) cephalograms can reduce errors in landmark identification on PA cephalograms.
METHODS
Five examiners identified 16 landmarks (Cg, N, ANS, GT, Me, RO, Lo, FM, Z, Or, Zyg, Cd, NC, Ms, M, and Ag) on 32 PA cephalograms with and without LA cephalograms at the same time. The positions of the landmarks were recorded and saved in the horizontal and vertical direction. The mean errors and standard deviation of landmarks location according to the use of LA cephalograms were compared for each landmark.
RESULTS
Relatively small errors were found for ANS, Me, Ms, and Ag, while relatively large errors were found for N, GT, Z, Or, and Cd. No significant difference was found between the horizontal and vertical errors for Z and Or, while large vertical errors were found for N, GT, and Cd. The value of identification error was lower when the landmarks were identified using LA cephalograms. Statistically significant error reductions were found at N and Cd with LA cephalograms, especially in the vertical direction.
CONCLUSIONS
The use of LA cephalograms during identification of landmarks on PA cephalograms could help reduce identification errors.

Keyword

Landmark identification error; Posteroanterior cephalogram; Lateral cephalogram

MeSH Terms

Facial Asymmetry

Figure

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  Figure 1 Head posture aligner used in this study.

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  Figure 2 Landmarks used in this study. Definition of each landmarks has been described in Table 1.

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  Figure 3 A flowchart showing the sequence in which the landmark identification procedure was performed. The first set of 16 cephalograms were examined twice with or without lateral cephalograms accordingly, including a washout period of 2 weeks. Two weeks following the first set, the identical procedure was repeated for the remaining 16 cephalograms to avoid the rehearsal effect. ceph, Cephalogram.

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  Figure 4 Scattergrams illustrating the errors of 5 landmarks identification in posteroanterior cephalograms with (A) and without (B) the use of lateral cephalograms.Definition of each landmarks has been described in Table 1.

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