Three-dimensional Analysis Of Nasolabial Soft Tissue Changes After Maxillary Anterior And Inferior Movement By Le Fort Ⅰ Osteotomy

Objective:To evaluate the nasolabial soft tissue changes of skeletal Class Ⅲ malocclusion patients after maxillary anterior and inferior movement using a three-dimensional measurement and evaluate the association between the nasolabial morphology indications and the maxillary anterior movement.To validate the consistency and accuracy of the measurements of the nasolabial soft tissue changes by the 3d MD vultus software.Method:From January 2017 to December 2017,45 consecutive patients with skeletal ClassⅢ malocclusion who underwent maxillary Le Fort Ⅰ osteotomy and sagittal split mandible osteotomy were enrolled in this study.Among these 45 patients,20 were male and 25 were female with an average age of 26.3 years old(range,20-35years).Patients’ skull CT data before surgery and at least 6 months after the surgery were selected and Proplan CMF 3.0 software was adopted to measure the three-dimensional movement of the maxilla and mandible.Data of the nasolabial soft tissue were acquired via three-dimensional photographs,while facial landmarks and nasolabial morphology were defined and measured by 3d MD vultus software.Then we try to establish statistical models to describe the relationship between the nasolabial indications and the maxillary anterior movement.At last,to validate the consistency and accuracy of the measurement of the nasolabial soft tissue changes by the software,the landmarks of the nasolabial area were measured twice at two different time by two observer and the Intraclass Correlation Coefficient of two measurements were calculated by the SPSS 22.0 software.Results:The nasolabial area of facial soft tissue changes following maxillary Le Fort Ⅰosteotomy for maxillary anterior and inferior movement.The width of alar and subalar increase after maxillary Le Fort Ⅰ osteotomy.The upper lip length and nasolabial angle increase,while the width of vermilion is statistically stable.We found there’s a non-linear relationship between the increase of the nasolabial angle and the maxillary anterior movement and clockwise rotation.However,the increase of the width of alar was not found to be associated with maxillary anterior movement,which may mean that the subalar width will increase no matter how the maxilla moves for an advancement.Besides,the Intraclass Correlation Coefficient of two measurements shows good consistency and accuracy of the nasolabial threedimensional measurement using the 3d MD vultus software.Conclusions:Bimaxillary orthognathic surgery procedures might widen the alar base,and may increase the nasolabial angle which were unpleasant outcomings for patients and should be taken in consideration before surgery.The study shows clearly of the postsurgical changes of the nasolabial area and validate the importance to evaluate and predict the surgical outcomings.Besides,3d MD photogrammetric system has advantages on the measurement of soft tissue changes and three-dimensional postoperative prediction.