Clinical manifestations of severe periodontitis are very often associated with tooth migration. The aim of this retrospective study is to evaluate dental bone support before orthodontic-periodontal treatment, at immediate postoperative, and long-term postoperative and to compare these results with those obtained from periodontal treatment alone. Fifteen patients (11 women and four men), all with severe periodontitis, mean age 42.8years (22–61), were followed for an average of 16years (11–32). Comparison was made between periodontal–orthodontic treatment (Group 1) and periodontal treatment alone (Group 2). Alveolar bone height was measured at T0 (before treatment), T1 (immediate postoperative) and T2 (long-term postoperative). Assessment was performed by means of digitized radiography using Image J Software from the National Institute of Health. The average postoperative observation period between T0 (before treatment) and T2 (long-term results) was 16years (11 to 32). Results showed an overall bone apposition in groups (1 and 2) immediately after treatment (T1), then at long-term (T2). No statistical difference was observed between both groups (1 and 2). In conclusion: an overall bone gain was observed in both treatment groups (periodontal–orthodontic and periodontal alone). The orthodontic treatment combined with periodontal treatment never compromised the benefits of periodontal treatment alone. On the opposite, it appeared to be quite beneficial.