[Study of biomechanical properties of mucosa scars after cleft palate surgery].

OBJECTIVE: To explore biomechanical properties and stress-strain of mucosa scars after cleft palate surgery. METHODS: After the model of mucosa scars was made, the mucosa scars and normal mucosa were excised and examined immediately by tensionometry. RESULTS: The mucosa scars after cleft palate surgery were compared with normal mucosa. The Poisson's ratio of mucosa scars and normal mucosa was 0.5 and 0.49, respectively, showing no significant difference between the two groups. The ultimate Young's modulus of mucosa scars was about 24.22 MPa, however, it declined to 3.32 Mpa in normal mucosa. CONCLUSIONS: The mucosa scars after cleft palate surgery are biomechanically weaker than normal mucosa. It can be used for further research, such as maxillary orthognathic surgery, distraction osteogenesis, and orthodontic treatment.

[Application of the cone beam computed tomography (CBCT) in Le Fort I osteotomy].

OBJECTIVE: To improve the accuracy and safety of the Le Fort I osteotomy. METHODS: Eighty-four patients underwent CBCT scan before maxillary orthognathic surgery. The anatomic structures of maxilla were marked and measured. RESULTS: In 84 cases, there were 3 cases with severe hypoplasia of maxillary sinus, 11 cases with impacted third molar, 8 cases with separation in maxillary sinus, 4 cases with the deviation of nasal septum, and 3 cases with cysts in maxillary sinus. Form CBCT images, the position of the pterygopalatine canal, the thickness of maxillary wall, hidden lesion of maxillary sinus, the location of Impacted molar, the deviation of nasal septum, and other anatomic structure could be accurately localized. CBCT could provide sufficient and valuable information in diagnosis and design for Le Fort I osteotomy. CONCLUSIONS: CBCT imaging technology could provide precise anatomic images for Le Fort I osteotomy. It improves the accuracy and safety of the Le Fort I osteotomy.

[Three-dimensional finite element analysis for external midface distraction after different osteotomy in patients with cleft lip and palate].

OBJECTIVE: To study three-dimensional finite element analysis for external midface distraction after different osteotomy in patients with cleft lip and palate (CLP). METHODS: Three-dimensional FEM models of Le Fort I, II and III osteotomy in CLP patients were established. External midface distraction were simulated. An anteriorly and inferiorly directed 900 g force was applied to bilateral maxillary arch in directions 30 degrees to the occlusal plane. Biomechanical changes for the maxillary complex were investigated by means of finite element analysis. RESULTS: Maxillary complex was advanced after different osteotomy. Constriction of alveolar crest and palate occurred in Le Fort I osteotomy, but not in Le Fort II and III osteotomy. Clockwise rotation occurred in Le Fort I osteotomy complex. Counterclockwise rotation occurred in Le Fort II and III osteotomy complex. CONCLUSIONS: Three-dimensional finite element research on external midface distraction could provide reference for the preoperative design.