OBJECTIVE: To evaluate the efficacy of occlusal improvement in the labial fixed orthodontic treatment in aggressive periodontitis patients and to explore the relationship between occlusal improvement and inflammation control. METHODS: Twenty-two aggressive periodontitis patients who underwent combined periodontal-orthodontic treatment were included in this study. The patient's photos were matched to the dental models and digital three dimentional models were acquired using 3Shape R700 laser scanner. The occlusal force distribution maps were generated in the OrthoAnalyzer software. The newly established occlusal force distribution score (OFDS) and proximal contact score (PCS) were used to evaluate the occlusal distribution changes before and after labial fixed orthodontic treatment for assessing the effectiveness of orthodontic treatment. The multi-level linear regression analysis was used to explore the relationship between the probing depth changes and OFDS or PCS changes to screen out the favorable orthodontic strategy for inflammation control, which would provide clinical strategy for combined periodontal-orthodontic treatment in aggressive periodontitis patients. RESULTS: At the patient level, OFDS was improved significantly after orthodontic treatment compared with the score before orthodontic treatment (84.5±20.9 vs.105.3±22.6, P <0.001) and PCS was improved significantly after orthodontic treatment compared with the score before orthodontic treatment (68.9±9.1 vs. 83.7±6.3, P <0.001).At the tooth level, the OFDS was significantly increased in the maxillary anterior teeth (P <0.001) while the PCS of the anterior teeth in both maxillary and mandible arches were significantly increased significantly (P <0.01). No significant changes were found in other tooth positions. The multilevel linear regression model showed that no significant correlation was found between age and gender and probing depth decrease (P >0.05). The baseline probing depth,OFDS improvements and PCS improvements (P <0.001) were positively correlated with probing depth decrease. CONCLUSION: This study showed that the distribution of occlusal force was more reasonable and the proximal contacts were more ideal in aggressive periodontitis patients. Orthodontic treatment was effective in improving occlusal force distribution by the above two ways. Especially, the OFDS and PCS improvements were both positively correlated with probing depth decrease, indicating that in the combined periodontal-orthodontic treatment for aggressive periodontitis patients, occlusal force distribution and proximal contact should be improved in order to facilitate periodontal improvement.