Does Clockwise Rotation of� Maxillomandibular Complex Using� Surgery-First Approach to Correct� Mandibular Prognathism Affect� Surgical Movement and Stability?

Does Clockwise Rotation of� Maxillomandibular Complex Using� Surgery-First Approach to Correct� Mandibular Prognathism Affect� Surgical Movement and Stability?

1. Does Clockwise Rotation of Maxillomandibular Complex Using Surgery-First Approach to Correct Mandibular Prognathism Affect Surgical Movement and Stability? Suraj Prasad Sinha, Nat Lilakitrungrueang , MS,y Thuy-Duong Tran Duy, Ellen Wen-Ching Ko, MS, Yu-Ray Chen, and Chiung Shing Huang

2. Journal of Oral and Maxillofacial Surgery DOI : https://doi.org/10.1016/j.joms.2022.09.007 Received on: march 14 2022 Accepted on: September 8 2022 Published in: January 2023

3. Wolford introduced rotation of MMC for optimizing functional and aesthetic outcomes during OGS. CCWR  mandibular advancement Corrects skeletal Class II malocclusion. Increases the pharyngeal airway space to improve OSA CWR  posterior rotation of mandible corrects skeletal Class III malocclusion

4. Orthognathic surgery (OGS) using the surgery-first approach (SFA) can decrease treatment time and increase patient satisfaction. The combined effect of the SFA and CWR of the MMC in correcting mandibular prognathism  NOT EXPLORED.

5. AIM To explore the combined effect of the SFA and CWR of the MMC to correct mandibular prognathism in terms of surgical movement immediately after OGS and post-operative stability 12 months after surgery

6. SPECIFIC OBJECTIVES To compare the surgical movements in the CWR and control (C) groups at T0-T1 (2) To compare the skeletal stability between the 2 groups at T1-T2.

7. Study Design Prospective cohort study Ethical review board: (201305585B0C601) Ethical approval no. Study design

8. Inclusion criteria Age group: > 18 years skeletal Class III malocclusion with a prognathic mandible undergo bimaxillary surgery using the SFA of OGS. exclusion criteria previous OGS history of trauma chin deviation ( menton deviations of >4 mm) postoperative infection at surgical sites, lack of data for 2 data points after Surgery craniofacial syndrome if they did not provide informed consent.

9. INTERVENTIONS No orthodontic force applied pre surgery Maxillary OP was used to measure the changes in the OP Since preoperative orthodontic treatment is not performed in the SFA, skeletal and dental changes represent the actual movement due to CWR of the MMC immediately after surgery. Fixation method 4 monocortical screws (2 x 6 mm) and 2 two-hole miniplates for BSSO 2 five-hole L shape miniplates (2.0 mm bar) for LeFort I osteotomy.

10. all postoperative orthodontic treatments were carried out between T1 and T2

11. PREDICTOR VARIABLE OP change at T0-T1 ≥ 4 °  the CWR group ≤ 4 °  C group OUTCOME VARIABLE stability of Pog at T1-T2 AP movement of Pog < 1 mm  stable group AP movement of Pog > 1 mm  unstable group

12. OTHER VARIABLEs demographic factors (age and sex) cephalometric measurements (SNA, SNB, ANB, AFH, PFH, LPFH, OP, MP, IMPA, OB, OJ) 3D landmark displacement (ANS; A-point, upper central incisor, upper first molar, lower central incisor, lower first molar, Pog , Go, and Co).

13. Sample calculation and randomization Sample size calculator: ClinCalc 25 per group

14. Data Collection CBCTs were performed at T0, T1 and T2 superimposition of 3D images was done mean 3D movement of skeletal and dental landmarks was calculated

15. Results Demographic data C Group CWR group Number of patients 28 (17 women) 36 (24 women) Mean age 23.89 years 24.08 years

16. BIVARIATE ASSOCIATIONS BETWEEN THE STUDY VARIABLES BASED ON PRIMARY PREDICTOR VARIABLE (CWR GROUP VS CONTROL GROUP) Owing to the CWR at T0-T1 SNB ↓ significantly ANB, OP angle and mandibular plane angle ↑ In the AP movement the upper incisor moved forward whereas the B-point, Pog , Go, lower incisors and lower molars moved backward In the vertical dimension the ANS, A-point, and upper incisor moved downward

17. BIVARIATE ASSOCIATIONS BETWEEN THE STUDY VARIABLES BASED ON PRIMARY OUTCOME VARIABLE (STABLE GROUP VS UNSTABLE GROUP) At T0-T1 unstable group: ↑ in SNB and ANB angles, and more backward movement of mandible at B point and lower central incisor. At T1-T2 the unstable group: more forward movement at B-point, Pog , condylion , upper first molar, and lower first molar All cephalometric measurements and vertical movement of landmarks showed no significant difference between these 2 groups at T1-T2.

18. BIVARIATE ASSOCIATION BETWEEN PRIMARY PREDICTOR (CWR VS CONTROL) AND PRIMARY OUTCOMEVARIABLE (STABLE GROUP VS UNSTABLE GROUP) P value- 0.663 no significant relationship between CWR and the stability of Pog at T1-T2.

19. ASSOCIATION BETWEEN OP CHANGE AND THE SIGNIFICANTLYAFFECTED COVARIATES AT T0-T1 At T0-T1, a large amount of CWR by increasing the OP significantly impacted the PNS Extruded the ANS Setback the Pog Increased the mandibular plane angle.

20. DISCUSSION This study investigated whether the surgical movement and postoperative stability would be affected by a large CWR of the MMC in patients undergoing bimaxillary surgery to correct mandibular prognathism

21. After surgery, skeletal and dental changes ( within 1 month ) showed a statistically significant amount of OP change in CWR group. downward displacement of maxilla More backward displacement of mandible Regarding the effects after12 months of treatment, the parameters were statistically insignificant , except for ANB, OP, and vertical movement of the U6

22. As stated in the literature, the parameters differed by <1mm in SFA and OFA, hence statistically insignificant.

23. Wolford et al, documented the following changes after CWR of the MMC during OGS increase in the OP increase in the mandibular plane angle posterior rotation of the chin and decreased prominence in the A-P position of the lower incisor decrease in the posterior facial height advancement of perinasal bone structures, decrease in the maxillary incisor angulation, increase in the mandibular incisor angulation.

24. 1) Increase in occlusal plane angle large CWR of MMC rotate the OP considerably, therefore leading to a more significant increase in the OP, average surgical increase in OP angulation ranges from 2.30 to 5.60. 2) Increase in mandibular plane angle Significantly increased postoperatively in the CWR group

25. 3) Posterior chin rotation and decrease in prominence in relation to the A-P position of the lower incisor mean horizontal setback at the B-point was significantly larger in the CWR group similar result for Pog and L1 indicate that CWR of the MMC rotates the chin more posteriorly and causes the lower incisors to become less prominent 4) Decrease in posterior facial height Immediate PFH increased in both the groups PFH ( sella -gonion) decreased substantially at T2

26. 5) Advancement of perinasal bone structures More perinasal advancement was observed in the CWR group than in C group 6 ) Decrease in maxillary incisor angulation U1 exhibited more significant setback in the CWR group The ANS and a-point exhibited more forward movement in the CWR group Causing the upper incisors to become upright

27. Postoperative Skeletal Stability at T1–T2 Proffit et al proposed that in orthognathic surgery, the change of landmarks <2mm  clinically insignificant. In this study CWR of the MMC does not show significant change in all cephalometric measurement and vertical movements of landmarks between stable and unstable groups. If at all there were some changes, it was <1.5mm 1 yr post op stability: SAME

28. conclusion The CWR of the MMC significantly increased the OP, displaced the maxilla vertically, and setback the mandible immediately after OGS, similar to those in the control group at 1 year after OGS. The digital analysis performed in the study allowed a more objective evaluation of the facial swelling, reducing costs and possible bias.

29. Critical evaluation

30. Positives Study design: Prospective cohort study Inclusion of Multiple Variables - wide range of cephalometric variables and 3D landmark displacements

31. Negatives Small sample size No CONSORT flowchart Follow up period – only 1 year Does not address functional outcomes. (only structural and cephalometric) No clinical or radiographic or other treatment planning pictures supporting the study

32. Thank you!