Discrepancies between centric occlusion and centric relation in orthodontically treated patients.

Condylar position between centric occlusion (CO) and centric relation (CR) was compared for 24 adolescent orthodontic patients at pretreatment, posttreatment, and during the retention phase of orthodontic treatment. Models were mounted using a face-bow transfer and CR interocclusal registrations. Differences in CO-CR were then measured at the condylar level in the x, y, and z dimensions. The data were analyzed statistically to determine the mean CO-CR differences in the sample as well as the magnitude and direction of the CO-CR differences from one time period to the next. Results showed that the mean three-dimensional distance between CO and CR tended to increase from pretreatment to the retention phase for the right and left sides, the left side showing a greater increase. Intraexaminer variability accounted for 20% to 25% of the total variability when all possible sources of variability were considered. Correlation with a second examiner in recording CR was in the range of .61 and .75 for the right and left sides, respectively. Interexaminer variability was found to be similar to the variability associated with the CO-CR discrepancies over time. Consequently, the differences in measurements obtained could be the result of changes in the CO-CR relationship, examiner variability, or a combination of both.