Aim: to evaluate change in occlusal plane inclination in relation with Frankfurt Plane in 2 groups of patients treated with extraction and with Straight-Wire appliance and self ligating brackets and with Edgewise Tweed appliance and conventional brackets respectively. Materials and methods: 20 patients with skeletal Class II, with crowding in permanent dentition divided in 2 groups, one treated with self ligating brackets the other treated with Tweed appliance and Standard Edgewise Brackets. Both groups treated with 4 first bicuspids extracion. Evaluated Occlusal Plane inclination on FH before and after orthodontic treatment with cefalometric superimposition on Best Fit and on FH. Results and discussion: in the group treated with self ligating brackets there is an anterotation in occlusal plane with the superimposition both on Best Fit (+2.5°), both on FH (+1,8°). In the group treated with Tweed appliance there is, in superimposition on Best Fit an occlusal plane anterotation (+0.9), in superimposition on FH an occlusal plane postrotation (-0.5°). Conclusions: Statistical analysis show in both cases a not statistical significative difference in angular variation.