The comparative study of three-dimensional cephalograms to actual models and conventional lateral cephalograma in linear and angular measurements

Bae, Gi Sun; Park, Soo Byung; Son, Woo Sung

Abstract

Conventional cephalometrics have inherent errors because their evaluation is performed in two-dimension for threedimensional object. To compensate these errors, three-dimensional cephalograms - derivation of three-dimensional data from conventional lateral and postero-anterior cephalograms - were developed. In this study, the accuracy and precision of three dimensional cephalograms were determined by means of 10 linear and 12 angular measurements on 36 acrylic skull models and by the comparison of conventional lateral cephalograms. The results were as follows 1. Mean difference between three-dimensional cephalograms and actual models in linear measurements was 0.94+/-0.62 mm and mean rate of magnification of three-dimensional cephalograms was 100.31+/-0.91%. There were no statistically significant differences between three-dimensional cephalograms and actual models in linear measurements(alpha=0.1). 2. Mean difference between conventional lateral cephalograms and actual models in linear measurements was 6.44+/-1.48 mm and mean rate of magnification of lateral cephalograms was 106.99+/-1.45%. There were statistically significant differences between lateral cephalograms and actual models in linear measurements(P<0.005). 3. Mean difference between three-dimensional cephalograms and actual models in angular measurements was 1.22+/-0.82degrees and mean rate of magnification of three-dimensional cephalograms was 105.71+/-12.07%. There were no statistically significant differences between three-dimensional cephalograms and actual models in angular measurements(alpha=0.1). 4. Mean difference between conventional lateral cephalograms and actual models in angular measurements was 1.70+/-0.94degrees and mean rate of magnification of lateral cephalograms was 106.35+/-15.70%. There were no statistically significant differences between lateral cephalograms and actual models in angular measurements(alpha=0.1). There were similarity between three-dimensional and lateral cephalograms in angular measurements.