Precision of cephalometric landmark identification three-dimensional vs two-dimensional.

摘要

The purpose of this study was to determine if half-skull and multiplanar reconstruction (MPR) images derived from CBCT image volumes will provide more precise location of landmarks and measurements than conventional cephalometric radiographs.;A population of 20 pre-treated surgical orthodontic patients was radiographed and evaluated using lateral cephalometric and CBCT techniques. Four radiographic displays were used: conventional cephalogram, right and left half CBCT cephs, and MPR. Precision was calculated for 23 landmarks, 4 modalities and 20 cases using two measures of observer variation for identifying the same landmark in the same case and modality: ODM (Observers difference from the mean) and DEO (Difference from Every other Observer). Analysis of Variance (ANOVA) was computed for ODM or DEO for all modalities, landmarks, coordinates, and cases as every effect as well as all interactions among them. Statistical significance was defined as an alpha level of 0.05. Paired- t Tests were also used to assess each of the two calculations of variability for each landmark and the 6 possible combinations of 4 modalities. Bonferroni correction for multiple comparisons was applied and a p threshold of 0.0036 was calculated. Landmark variability clinically important used a threshold of 2mm.;Results indicate that overall statistically landmark variation was greater for conventional cephalogram than CBCT modalities when calculated using ODM and DEO approaches. The x and y overall modality variability were higher for conventional cephalograms than for any of the alternative modalities. Landmark variability over 2 mm was greater for conventional cephalogram for more than half of the landmarks. Only soft tissue Pogonion exceeded the 2mm for all modalities.;Based on the results of this study is possible to conclude that CBCT modalities provide a more precise location of landmarks overcoming problems obtained with conventional cephalograms.