Orthodontic closure in cases of aplasia as also in patients with spaces of other genesis is often associated with problems of relapse. In this study ten patients were treated orthodontically in order to close unacceptable interdental spaces. Five patients had paired aplasia. The remaining five patients had interdental spaces of different genesis. Supra-crestal connective tissue fibres were surgically removed in all patients but only on one side of the jaw in the children with paired aplasia. The non-operated side of these children served as a control side. The stability of the orthodontic treatment was acceptable. No definite difference between the operated and the control side was recorded. The histological analysis of the removed tissue did not reveal anything unexpected but a rich infiltration of inflammatory cells. It is suggested that inflammation might aid the reorganization of the connective tissues in this area.