Dentoalveolar ankylosis of a tooth is a serious complication in growing individuals. The ankylosed root is continuously resorbed and replaced by bone, and an infraposition of the damaged tooth will develop. The normal alveolar development will be disrupted in this way, and prosthetic treatment will be compromised. Therefore, an ankylosed tooth should be removed before future orthodontic and/or prosthetic therapy is jeopardized. This article will present a method, decoronation, to remove an ankylosed tooth in such a way that the alveolar ridge is preserved and give guidelines for the timing to intervene. The decoronation method is described, and a possible explanation for the favorable outcome is discussed. Different aids to decide the time for intervention are presented. The alveolar ridge was maintained in buccal/palatinal direction, and the bone level increased after decoronation in patients treated before or during pubertal growth periods. The bone level also increased in those treated after this period but not at the same rate, and in a few patients it was unchanged. The clinical finding that decoronation can maintain or reestablish normal alveolar conditions is important for successful implant insertion later.