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[Sensitivity of four representative angular cephalometric measures]
T Xü1, J Ahn, S Baumrind
1Department of Orthodontics, School of Stomatology, Beijing Medical University, Beijing 100081, China.
Objective:
Examined the sensitivity of four representative cephalometric angles to the detection of different vectors of craniofacial growth.
Methods:
Landmark coordinate data from a stratified random sample of 48 adolescent subjects were used to calculate conventional values for changes between the pretreatment and end-of-treatment lateral cephalograms. By modifying the end-of-treatment coordinate values appropriately, the angular changes could be recalculated reflecting three hypothetical situations: Case 1. What if there were no downward landmark displacement between timepoints? Case 2. What if there were no forward landmark displacement between timepoints? Case 3. What if there were no Nasion change? These questions were asked for four representative cephalometric angles: SNA, ANB, NAPg and UI-SN.
Results:
For Case 1, the associations (r) between the baseline and the modified measure for the three angles were very highly significant (P < 0.001) with r2 values no lower than 0.94! For Case 2, however, the associations were much weaker and no r value reached significance.
Conclusions:
These angular measurements are less sensitive for measuring downward landmark displacement than they are for measuring forward landmark displacement.