[Surgery First : prediction for skeletal objectives through structural analysis. Comparison of Sassouni and Delaire analysis].

INTRODUCTION: The purpose of this study was to compare two structural cephalometric analysis (Delaire and Sassouni) as surgical decision tools. These two analyses do not include dental compensation for skeletal discrepancies and have been proven reliable especially for the Sendai surgery first protocol developed by Sugawara.

MATERIAL AND METHOD: The two analysis were performed on 20 surgical cases and the proposed skeletal modifications were compared in order to measure the differences and see if those differences varied according to the facial type. For 10 cases the Virtual Surgical Planning (VSP) images obtained from Dolphin 11.95 Premium software (based on the presurgical CBCT and facial photographs) allowed a comparison of the two analyses as surgical decision indicators and to the realised surgical procedure. The VSP photographs obtained were graded by two panels: one professional and the other one non professional.

RESULTS: Sassouni's analysis favored more forward movements for the maxilla (ENA +5,45) as well as more vertical modifications (Me 1,595). The facial type did not appear to have a significant effect. The quality of Dolphin VSP prediction was judged rather reliable above average (3.7/6) by the panels. The VSP photographs obtained from the two analyses were presented to the panels as well as the VSP obtained from the actual surgery. The three facial outcomes: Sassouni, Delaire and "Surgery Realised" called Dolphin showed some potentially interesting differences. The small size of the sample did not show any significant findings (t test) but a special analysis revealed a valid difference between the three outcomes. The most aesthetic being Dolphin (surgery realised) 17.4 then Sassouni 16.6 (diff 0.8) and finally Delaire 14 (diff 2.6).

CONCLUSIONS: The two structural analysis Delaire and Sassouni did not give the same surgical objectives. Sassouni favored more forward movements for the maxilla as well as more vertical modifications. The Dolphin software appeared to be the quite reliable software to predict the facial outcomes of the surgery. The VSP photographs obtained using Sassouni's analysis were more balanced than when the Delaire analysis was followed (16.4/14 = +2.6). The VSP based on the actual surgery was judged to be even more aesthetic. This shows that beyond a cephalometric analysis the facial aesthetic details and the functional analysis are very important during the phase of surgical planning.