The paper presents the results of two years observation of clinical application of three variants of space maintainers in early primary molars loss. Sixty-five children aged 6-12 years were included in the study. The most common problems when using fixed space maintainers is a deformation of intermediate part seen in 58.3% of children when applying crown (ring) with bracer. Support elements debonding at stabilizing devise fixed directly to tooth enamel is registered in 49.6% of children. Cementation releasing of support elements is observed by the application of crown (ring) with bracer at 45.8% of children.