Postoperative Skeletal Stability Following Clockwise and Counter-Clockwise Rotation of the Maxillomandibular Complex Compared to Conventional Orthognathic Treatment
(Reyneke et al., British Journal of Oral and Maxillofacial Surgery, 2007, DOI: 10.1016/j.bjoms.2005.12.015)
Introduction
This study investigates the postoperative skeletal stability of the maxillomandibular complex (MMC) following clockwise (CR) and counter-clockwise (CCR) rotational movements during bimaxillary orthognathic surgery. The rotation of the MMC changes the occlusal plane angle, which is often necessary for achieving optimal facial balance and occlusal function.
One of the major concerns after such rotational repositioning is long-term skeletal relapse. While conventional orthognathic procedures (CT) have been widely studied, few have directly compared the stability of rotated MMCs. Therefore, this study aimed to determine whether such rotational movements can maintain comparable postoperative stability to conventional techniques.
Objectives
The authors sought to:
1. Compare long-term skeletal stability among patients undergoing CR, CCR, and CT approaches.
2. Identify whether rotational techniques cause increased skeletal relapse compared to standard bimaxillary procedures.
3. Examine the time frame during which postoperative changes occur.
Materials and Methods
This comparative clinical study included adult patients who underwent bimaxillary osteotomies (Le Fort I and bilateral sagittal split osteotomies) at a maxillofacial surgery unit in Johannesburg, South Africa.
• Group 1 (CR): Clockwise rotation of the MMC—used mainly to increase the occlusal plane angle or correct vertical maxillary excess.
• Group 2 (CCR): Counter-clockwise rotation—used to reduce the occlusal plane angle or improve facial convexity.
• Group 3 (CT): Conventional bimaxillary orthognathic surgery without significant rotational change.
Rigid internal fixation techniques were employed in all cases. Cephalometric radiographs were used to evaluate skeletal stability over a long follow-up period. Key parameters measured included changes in mandibular and maxillary positions relative to stable cranial reference points.
Results
• Both CR and CCR groups showed excellent postoperative stability, comparable to the conventional treatment group.
• No statistically significant differences in relapse magnitude were found among the three groups.
• Most skeletal changes occurred within the first 6 to 12 months after surgery, followed by minimal movement thereafter.
• The rigid fixation technique played a crucial role in maintaining stability across all surgical approaches.
These findings indicate that rotational repositioning of the MMC, when properly stabilized, can be as reliable as conventional orthognathic movements.
Discussion
The authors highlight that changing the occlusal plane angle via rotation offers important esthetic and functional benefits, such as improving facial harmony and occlusal relationships. However, surgeons have traditionally been cautious due to concerns about postoperative relapse.
This study challenges that concern by demonstrating equivalent skeletal stability for both CR and CCR techniques, provided that rigid fixation and proper case selection are ensured.
They also stress that the choice of rotation direction should be guided by individual patient characteristics:
• Clockwise rotation (CR) is suitable for long-face patients needing occlusal plane steepening.
• Counter-clockwise rotation (CCR) benefits short-face or class II patients requiring occlusal plane flattening.
Furthermore, the study underlines the necessity of accurate planning, stable fixation, and comprehensive orthodontic support before and after surgery.
Limitations
• The study was single-center, limiting generalizability.
• Sample size was modest, and subgroup analyses for TMJ status or soft-tissue effects were not performed.
• Long-term relapse beyond the follow-up period remains uncertain.
• External factors like surgeon experience and orthodontic variability were not fully controlled.
Conclusions
1. MMC rotation (both CR and CCR) in bimaxillary surgery can achieve postoperative skeletal stability comparable to conventional treatment.
2. Rigid internal fixation is critical to prevent relapse.
3. Relapse, if it occurs, tends to appear early (within the first postoperative year).
4. Rotation selection should be patient-specific, based on facial morphology and occlusal goals.
5. The findings support the safe and predictable use of rotational approaches to improve occlusal plane orientation and facial aesthetics.
In summary, this study provides evidence that rotational orthognathic movements can be both stable and esthetically beneficial, opening the door for greater surgical flexibility and precision
