ABSTRACT OBJECTIVES: To study the correlation between pharyngeal airway volume (PAV), the clinical indicators of obstructive sleep apnea (AHI, ESS), and the impact of orthognathic surgery on them.

METHODS: A prospective, descriptive, unicentric study carried out by a multidisciplinary team to evaluate the following parameters in patients undergoing orthognathic surgery at Maxillofacial institute Teknon medical center.

During the study period:

• Record of the type, magnitude and direction of surgical movements of the maxillofacial complex made during the surgery (Day 0-Month 1).

• Assessment of PAS/PAV stability (relapse) at short term (1 month).

  3D PAV assessment by cranial voxel-based superimposition protocol before and one month and 12 months after orthognathic surgery.

• Household polysomnography (PSG) registry/ apnea-hypopnea index (Day 0, Month 1 and Month 12). (AHI evaluation bu neurophysiologist)

• Assessment of the clinical indicators of obstructive sleep apnea at day 0, month 1 and month 12:, blood pressure (mm Hg) , and daytime hypersomnia test (Epworth sleepiness scale, ESS) (Day 0, Month 1 and Month 12).

• Record of body mass index (BMI) (cm/Kg2)

Main Objective:

• Evaluate the impact of orthognathic surgery (bimaxillary or monomaxillary) and its movements on the PAV and the clinical indicators of OSA.

Specific objectives:

• Interrelate the degree of dentofacial deformity with the IAH.

• Study the potential correlation between the volume of the VAS and the IAH.
• Correlate the type, direction and magnitude of the surgical movements of the maxillofacial complex with PAV/PAS increase Correlate the type, direction and magnitude of the surgical movements of the maxillofacial complex with the cure of OSA (household PSG AHI assessment) and the following clinical indicators of OSA: diurnal hypersomnia test (ESD, ESS).
• Evaluate negative effects of either maxillary or mandibular surgical movements in PAS/PAV increase and the cures of OSA.

Evaluate negative effects of either maxillary or mandibular surgical movements in the improvement of the clinical symptoms and the cure of OSA.

• To study the possible effect of surgical complications on PAS/PAV stability at long term and the clinical symptoms of OSA.
• Demonstrate that maxillomandibular surgery is a defined, predictable and a definitive cure for OSA.
• Demonstrate that skeletal, linear, and cross-sectional volume parameters remain stable at long-term.
• Demonstrate that AHI and OSA-related parameters stay stable at long term after mono- or bimaxillary surgery.

Hypothesis

• H1a: Maxillomandibular advancement (orthognathic surgery) does correlate with the volume of the upper airway, at both short or long term.
• H2a: Maxillomandibular advancement (orthognathic surgery) does correlate with the clinical indicators of obstructive sleep apnea, at both short or long term.

Inclusion Criteria:

1. Patients over 18 years of age who present any kind of dentofacial deformity candidates for orthognathic surgery treatment.
2. Growth of the maxillofacial complex completed.
3. Patients without uncontrolled cardio-pulmonary disease.
4. Patients willing to understand the procedures of the study and that agree to give their signed informed consent.
5. Patients who commit to perform the postoperative controls for at least one postoperative year.
6. Patients with a good general condition of health, confirmed by pre-operative study and assessment by Anaesthesiology (ASA).

Exclusion Criteria:

1. Patients with a clinical history in which any surgery would be contraindicated
2. Patients with any facial Syndromic malformation
3. Patients who have undergone chemotherapy or radiotherapy during the last 5 years, including area of head and neck.
4. Patients who refuse to accept the clinical conditions of the study and are not willing to sign the form corresponding informed consent.
5. Patients who are expected to lack adherence to follow-up or to the treatment.
6. Treatment with bisphosphonates or Denosumab (Prolia®).