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The inapplicability of formulae to determine vertical dimension
Author(s) -
Darvell B. W.,
Spratley M. H.
Publication year - 1979
Publication title -
australian dental journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.701
H-Index - 71
eISSN - 1834-7819
pISSN - 0045-0421
DOI - 10.1111/j.1834-7819.1979.tb03597.x
Subject(s) - standard deviation , mathematics , dimension (graph theory) , standard error , statistics , orthodontics , radiography , dentistry , medicine , surgery , combinatorics
A bstract — The accuracy and precision of certain external cephalometric measurements were investigated on a subject presenting optimal conditions, using ten operators. Due to difficulties in identifying landmarks and tissue compressibility, the standard deviation of a measurement for ten replications ranged from 0.3 to 1.7 mm, while the “between operators” standard deviation was no better than 2.0 mm. Measurement accuracy was also poor; that of primary interest, subnasale‐gnathion, had a bias of the order of 7 mm, judged by a radiographic determination. A minimum denture success rate of 97 per cent is equated with a standard deviation of 1 mm in the design freeway space. A recently published regression equation for predicting occlusal vertical dimension has a minimum error of prediction of 5.8 mm and thus is considered an inadequate predictive tool. The errors demonstrated in facial measurements suggest that using formulae to predict occlusal vertical dimension is unlikely to produce clinically acceptable results.