Currently, extraction is increasingly avoided to alleviate crowding. This study aimed to evaluate changes in the buccal alveolar bone during the alignment phase of orthodontic treatment without extractions using cone beam computed tomographic. Two reviewers, without regard to language limitations, performed a manual search through June 2024 and an electronic search of web databases (Medline, Science Direct, Scopus, and Web of Science). Clinical studies, both randomised and non-randomized, were considered. Utilising the Cochrane risk of bias tool for randomised trials, the same reviewers evaluated the studies' quality. And the Methodological Index for Nonrandomized Studies (MINORS). A total of 2815 records were initially identified. Following title and abstract screening, the full texts of thirty studies were reviewed, and eight studies met the selection criteria and were included in the review. All studies reported unfavourable changes in the bone structure following non-extraction treatment, affecting both the bone thickness and height of maxillary and mandibular incisors; premolars, and the mesiobuccal root of maxillary first molars. Non-extraction alignment of dental crowding resulted in significant bone loss, of both bone thickness and height. These results must be taken into account in non-extraction treatments, to prevent the iatrogenic effects of this therapeutic approach.
