Orthosurgical treatment is recommended for the correction of dentofacial deformities and often involves bimaxillary surgery. This procedure can be performed by altering the patient’s maxillomandibular complex (MMC) in order to optimize final functional (dental occlusion, respiration, temporomandibular joint (TMJ) and long-term stability) and aesthetic results.

Orthognathic surgery may be performed by means of ‘conventional’ treatment, or be complemented with clockwise or counterclockwise MMC rotation. ‘Conventional’ treatment is understood to be that where the cephalometric prediction tracing is able to correct antero-posterior maxillomandibular discrepancies through the pre-existing occlusal plane, and the final occlusal plane is determined by the mandibular occlusal plane after its autorotation, which occurs both clockwise and counterclockwise at a superior–posterior point to the condyle, depending, respectively, on the inferior or superior repositioning of the maxilla. Surgical planning that includes MMC occurs independently of a pre-existing mandibular occlusal plane.

In bimaxillary surgery cases, the vertical position of the upper incisors, the antero-posterior position of the maxilla, and the angulation of the occlusal plane are taken into account. These factors dictate the position of the mandible and affect both functional and aesthetic results. The impacts of these alterations have major implications for surgical planning, and long-term aesthetic stability and function of the stomatognathic system are of the utmost importance.

A specific treatment proposal is established according to the type of dentofacial deformity, by evaluating the surgical movements to be performed as well as aesthetic and functional effects on clinical and cephalometric variables that occur after orthognathic surgery.

The possibility of occlusal plane management in bimaxillary surgery was first described in the literature in 1985. Nevertheless, Wolford and Hilliard had already performed an occlusal plane alteration through MMC counterclockwise rotation as a differentiated surgical approach applied to a Class II patient in 1979, but this procedure was only publicized several years later.

There must be a correlation between clinical evaluation data (facial analysis) and cephalometric analysis so as to aid in the establishment of a surgical treatment plan. However, these data do not always correlate due to the abnormal orientation of the Frankfort plane, which must be corrected. The normal occlusal plane angular relation must be 8 ± 4° in relation to the Frankfort plane.

Autorotation of the mandible – following either the superior or inferior repositioning of the maxilla where the mandible can be repositioned without surgical manipulation – is one of the most stable long-term procedures in orthognathic surgery. This treatment is recommended for patients with excessive exposure of anterior and superior teeth at rest or smiling, or in large inter-labial distance cases, generating labial incompetence. These patients usually present anterior open bite and Angle’s Class II or I, where the superior and anterior repositioning of the maxilla with autorotation of the mandible will keep a Class I occlusion, only interfering in aesthetic improvement.

In situations where there is a decrease in the occlusal plane angulation (<4°), the gonial angle is very prominent, the chin very pronounced in relation to the alveolar process, and in cases where there is Angle’s Class II division 2 malocclusion (Class I or III may also occur) and deep overbite, the most acceptable treatment proposed is clockwise MMC rotation, i.e., an increase in the occlusal plane inclination.

For patients with an increase in occlusal plane angulation (>12°), mandibular deficiency, anterior vertical maxillary excess, and decreased chin projection, counterclockwise rotation is the most appropriate procedure, resulting in a decreased inclination of the occlusal plane angle. This technique limits the correction of Class III patients and is largely used in the treatment of patients suffering from obstructive sleep apnoea/hypopnoea syndrome (OSAHS).

Complementary genioplasty to MMC rotation allows optimization of the aesthetic results in both movements, and the shape of the chin plays an important role in the surgery decision-making process, provided that this is more important than its antero-posterior positioning (horizontal pogonion position).

Based on these concepts, the aim of the current study was to perform a systematic literature review of the functional and aesthetic implications of MMC clockwise or counterclockwise rotation in orthognathic surgery, including evaluation of skeletal stability, aesthetics, and respiratory and TMJ function.

Methodology

A flowchart of the selection and evaluation procedure is given in Fig. 1 .

Flow diagram of study selection; PRISMA.

Following the initial selection and amalgamation of the first two search topic lines (‘alteration’ × ‘rotation’) by the three reviewers, a total of 16 potentially relevant items were identified, among which six were duplicates, i.e., these papers were found in both the ‘alteration’ and ‘rotation’ groups; so a shortlist of 10 relevant articles was reached. Two further articles found through the ‘autorotation’ search item were added, thus reaching a sample of 12 relevant articles; two of these were duplicates, i.e., they were found in the ‘alteration’/’rotation’ and ‘autorotation’ groups. A final sample of 10 relevant articles was then accessed fully and analyzed.