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[Application of 3D printing technique in bilateral sagittal split osteotomy].

OBJECTIVE
To investigate the application of osteotomy template manufactured via 3D printing technique in bilateral sagittal split osteotomy (BSSO).


METHODS
The patient group consisted of 32 patients (17 males and 15 females) with mandibular hypoplasia who underwent a BSSO setback (Hunsuck modification; 64 splits). The mean age at the time of surgery was 23.5 years (range 1.9-35 years). All patients were scanned using cone beam computed tomography (CBCT) to create a 3D model of the mandibular, and the osteotomy template of the inner horizontal ramus of mandible bone incision was manufactured via 3D printing technique. All splits underwent operation with or without the osteotomy template by either a young doctor (attending doctor) or a doctor with extensive orthognathic surgery experience (chief doctor). The time it took to perform the mandible bone incision of the inner horizontal ramus of each group was recorded. Postoperative CBCT scan was performed, and the lingual split scale was used to assess the effect of the operation.


RESULTS
Primary healing of incisions was observed in all patients, and no serious complications occurred. The time it took to perform the mandible bone incision of the inner horizontal ramus was significantly different in the four groups (F=30.059, P<0.05), and it was longer in the group of the attending doctor without osteotomy template than in the other three groups (P<0.05). No significant difference was observed in the other groups (P>0.05). Although all splits (n=64) were performed according to the standardized protocol, only 59.38% (38/64) of the fracture lines run according to the Hunsuck's description. By contrast, only 21.88% (14/64) run through the mandibular canal and 18.75% (12/64) was split. The database was analyzed using crosstabs and via Fisher exact test. The split pattern was influenced by the application of an osteotomy template (P<0.05).


CONCLUSION
The application of osteotomy template manufactured via 3D printing technique in BSSO was effective, which enabled the young doctor to complete the operation faster and with good results.