Korean J Orthod.
1999 Oct;29(5):563-573.
Reproducibility and accuracy of tooth size measurements obtained by the use of computer
- Affiliations
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- 1Department of Orthodontics, College of Dentistry, Chonnam National University, Korea.
Abstract
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The purpose of this study was to evaluate the availability of computer system for the
measurement of tooth size in the model analysis through the comparison of two
measurements: One was to use a computer; and the other was to use vernier calipers.
Twenty sets of casts were used, which showed a moderate degree of crowding and full
eruption of all teeth. The mesio-distal width of 12 teeth from the left central incisor to
the left first molar at each set of the casts were measured twice with vernier calipers
and a computer respectively. This measurement was repeated two weeks later. First, for
the reproducibility analysis, the two computer measurements were compared then the
vernier calipers measurements were compared. Second, all the teeth were sepapated into
the region of mesiodistal contact points and its width was measured by a micrometer to
obtain standard measurements. For the accuracy analysis, these standard measurements
were compared with the measurements from the dental casts using two methods. The
difference between them was defined as the measurement error. To investigate the
cause of measurement error, an examination was made for the presence and degree of
contact point deviation on each tooth from the upper and lower occlusograms, and the
mesio-distal angulation of each tooth was measured with TARG. Following results were
obtained through statistical analysis.
1. In the analysis for reproducibility ; the measurements with vernier calipers showed
significant differences in three out of twelve teeth while the computer measurements
showed significant differences in one out of twelve teeth.
2. In the analysis for accuracy : compared with the standard measurements, the
measurements with vernier calipers showed significant differences in three out of twelve
teeth while the compute measurements showed significant differences in two out of
twelve teeth.
3. Compared with the standard measurements. the measurements with vernier calipers
were apt to be larger at the upper first molar, and smaller at the lower first molar. The
computer measurements, however, were apt to be larger at both upper and lower first
molars.
4. the measurements with vernier calipers showed the largest error at the lowe first
molar and the degree of error was variable according to the tooth while the difference
of error was small in the computer measurements.
5. In the analysis for the correlation of the degree of measurement errors with the
contact point deviation index and the mesio-distal crown angulation of each tooth, the
measurements with vernier calipers did not show significant correlation while th
measurements with computer showed slight positive correlations.
The results of this study indicate that a computer system may be useful for the
measurement of tooth size in the model analysis.