Le Fort I osteotomy is often used in orthognathic surgery for patients to solve midface retrusion. It is known that post-surgical stability of Le Fort I osteotomy can be influenced by single jaw or bimaxillary procedures, fixation techniques or interpositional grafting. In patients with cleft lip and palate, the postoperative instability of Le Fort I osteotomy can be even worse due to scar tissue resulted from palate surgery. Segmental LeFort I osteotomy is another useful surgical modifications that can be easily done through the alveolar cleft. It is performed to allow the correction of differences in the occlusal planes, correction of transverse discrepancy or to facilitate an optimal occlusion. The most important benefits is that the alveolar cleft in patients who have not had alveolar bone graft surgery or failed to have successful result can be narrow down or even closed by approximation of two separating alveolar segments. However, there are limited previous studies comparing the stability of segmental versus one-piece Le Fort I osteotomy especially in patients with cleft. It is our aim to investigate whether one-piece Le Fort I osteotomy or segmental Le Fort I osteotomy can provide a better stability after surgery.

Measurements Skeletal movement

1. Skeletal Surgical movement from T2 to T1

   • positional change of landmarks in vertical from constructed Frankfurt plane
   • positional change of landmarks in horizontal plane in relative to constructed coronal plane through Sella point

2. Post-Surgical skeletal movement (Stability) from T3 to T2

   • positional change of landmarks in vertical from constructed Frankfurt plane
   • positional change of landmarks in horizontal plane in relative to constructed coronal plane through Sella point

3. Skeletal angular measurement change on mid-sagittal plane from (T2 to T1) and (T3 to T2)

4. Dental change measured from digital maxillary cast in transverse direction from (T2 to T1) and (T3 to T2)

5. Facial Height / Facial Proportion changes from (T2 to T1) and (T3 to T2)

6. Alveolar cleft width changes from (T2 to T1) and (T3 to T2)

Inclusion Criteria:

1. Cleft lip/palate patients
2. Non growing Taiwanese adults, at least 18 years old for men and 16 years old for women
3. Patients with midface retrusion and malocclusion that will need Le Fort I osteotomy
4. Rigid fixation with bone plates
5. Patients who signs the informed consent form

Exclusion Criteria:

1. Association with craniofacial anomalies
2. Patient without complete 3D imaging records including CBCT scans and digital dental models