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The articulatory displacement of maxillary bones during and after rapid maxillary expansion (RME) was studied with metallic implants and roentgen stereometry (RSA) for 3653 days in a girl aged 12 at start of treatment. She had a narrow upper dental arch with anterior crowding and a normal incisor relationship, and a normal sagittal molar relationship with bilateral cross-bite. Three implants were inserted in each maxillary bone and they remained stable in the bones during the 10-year observation period. In the 3-D analysis of the articulatory displacement, the left maxillary bone was studied in relation to the right bone in three periods: RME (23 days), retention (108 days) and follow-up (3522 days). Extensive relapse of rotations as well as translations was found and the long-term effect of RME was limited. In our opinion the relapse was caused mainly by the resistance to deformation from circum-maxillary sutures and surrounding soft tissue matrix, and inadequate bone formation in the involved sutures. As is generally known in clinical oral orthopaedics, changes obtained by short-term simple mechanical interference with a complex biological system tend to reverse spontaneously. Thus, the rationale for RME treatment may be seriously questioned.