Objective: determine the changes of alveolar bone level following intrusion and extrusion orthodontic movement of mandibular incisors.M & M: 20 patients divided into 2 groups; (I): extrusion group (II): intrusion group pretreatment and post-treatment CBCT & measurements of alveolar bone level in all aspects of the mandibular incisors by Mimics software. The obtained data were statistically analyzed.Results: In group (I), the mandibular lateral incisors showed greater but still statistically non-significant (P >0.05) alveolar bone loss than mandibular central incisors. The lingual aspect of the mandibular lateral incisors showed greater and statistically significant loss (P < 0.05) than the same aspect of the mandibular central incisor (0.70 + 0.13-0.60 + 0.14 respectively). In group (II), there were non-significant alveolar bone changes between mandibular central and lateral incisors. Comparison between the combined sites between group (I) and (II) revealed that, there was a significant greater loss (P < 0.05) in the mesial side of the central incisors in extrusion group than in intrusion group (1.26 + 0.29-1.12 + 0.12 respectively), while a more significant loss in the buccal and lingual side of central incisors in group (II) than group (I). The decrease of the alveolar bone level of lower lateral incisors was significantly greater in the distal side of extrusion group than intrusion group.Conclusions: The mandibular lateral incisors when compared with mandibular central incisors showed a greater amount of bone loss particularly the lingual aspect. Greater bone loss of the buccal and lingual aspects of mandibular incisors in group(II) than in group(I)