To explore the stability of anatomical markers in the measurement of craniomaxillofacial three-dimensional head shadow.

First, 20 cases of normal population were collected for maxillofacial CT data, respectively for 3d reconstruction of soft and hard tissue, and then the reconstructed 3d skull data were imported into Geomagic Studio 2014 software. Use the object shifter function of the software to determine the measurement head position and re-establish the coordinate system. Secondly, software operation training was conducted after 3 subjects were given the anatomical definition of 45 soft and hard tissue anatomical markers commonly used in clinical practice. After 2 weeks, 20 cranial data were determined and measured respectively according to the time interval of 0 month, 1 month and 2 months, and the coordinate values of each marker were analyzed by using the intra-group correlation coefficient (ICC) .

The results were 0.75 ~ 0.9 for the observer ICC of 5 markers, stilzvr, ZvL, OrL, PR and PL, indicating that repeatability was acceptable. The ICC results among the observers of five mark points, namely ZvR, ZvL, OrL, ZpR, ZpL, were between 0.75 and 0.9, indicating that repeatability was acceptable. Among them, 2 mark points, ZpR and ZpL, were mainly shown as abnormal on the Y-axis. The results of the ICC in and between the observers of 3 markers, such as the bahnans, BcR, and BcL, were<0.75, indicating poor repeatability and mainly focused on the instability of the X-axis. The interobserver ICC<0.75 between the two markers, such as fs, PL, etc., represents poor repeatability and is mainly the instability of the X-axis. The ICC values of the remaining 35 anatomical markers in and between the observers were greater than or equal to 0.9, which was highly repeatable.

In the measurement of three-dimensional head shadow of the craniomaxillofacial anatomical markers, the stability of the conventional fixed point method is limited, which cannot guarantee the high reliability of all the anatomical markers. It is necessary to establish another fixed point method to supplement it, so as to provide help for more accurate diagnosis and evaluation.