The assessment of antero-posterior dental base relationships.

The reliability and validity of four methods of assessing skeletal pattern (Reidel's method, Eastman correction, Ballard's method, and 'Wits' analysis) from cephalometric tracings have been examined, and the levels of agreement between them investigated. The possibility of the Y-axis length and SN-Y-axis angle having a bearing on the skeletal pattern was also examined. Strong correlation was found between the four methods considered. Ballard's method correlated very closely with Reidel's method, and like 'Wits' method, is not as unreliable as previously reported. Measurement of the SN-Y-axis angle was not found to be of benefit to the assessment of the anteroposterior dental base relationship. Reidel's method, which is the easiest to apply, is recommended as the method of choice, and routine application of the Eastman correction is not recommended.