Aim: Identification of bone changes due to remodelling at the top of the alveolar ridge and changes of the bone next to the root apex during the intrusive movement.
Materials and Methods: 16 patients whose treatment plan involved extraction of premolars were included in the set. The forces of 50g and 150g were applied on the maxillary first molars for 6 months. Before and after the intrusion, the CT scans in longitudinal tooth axis in vestibulooral dimension were made. We followed the length of the tooth, root and crown, the relationship between the apex and sinus maxillaris, and the relationship between CEJ and the alveolar ridge. The results were compared with the actual length of the teeth extracted.
Results: The application of intrusive force for six months together with the physiological relationship between the alveolar crest and cementum-enamel junction led to the inception of “bone sulcus”. The mean value of the sulcus was 0.63mm (light force of 50g), and 2.17mm (heavy force of 150g). When the force of 50g was applied, the bone sulcus represented 41% of the intrusion; when the force of 150g was applied, the sulcus represented 44% of the intrusion. Therefore, we assume that it is possible to move the tooth into the bone by this extent.
Conclusion: During intrusion, the alveolar ridge dislocated in the direction of the tooth movement, and the tooth was partially shifted into the bone. In case the tooth moved into the bone in the area of enamel, the bone sulcus formed.