After 2 weeks of "deprogramming" with an occlusal splint, 92 subjects with a history of comprehensive orthodontic therapy had an average centric slide that was comparable not only to that of an untreated control group, but also to equivalent estimates reported in the literature. It is suggested that for modern man a CO-CR difference may be a normal, physiologically significant by-product of the nature and pattern of mandibular function and the tooth attachment mechanism. Moderate changes in the magnitude of a given patient's centric slide would therefore be expected to regress, not to the population mean, but rather to the CO-CR difference that was present before treatment.