Orthognathic surgery is a surgical procedure involving one or both jaws to correct skeletal discrepancies, restore proper occlusion, and improve facial aesthetics. Individuals with dentofacial abnormalities often experience difficulties with chewing, biting, and social interaction, which may negatively impact psychological well-being and overall quality of life.

Orthognathic surgery must be combined with orthodontic treatment before and after the operation to ensure optimal functional and aesthetic outcomes. The conventional "orthodontics-first" approach involves prolonged preoperative orthodontic treatment (typically 12-24 months, sometimes up to 48 months) to decompensate dental alignment and reveal the true skeletal discrepancy prior to surgery. Although effective for achieving stable occlusion, this method is time-consuming and may temporarily worsen facial aesthetics and function during the preoperative phase.

The "surgery-first" approach eliminates or significantly reduces preoperative orthodontics, performing surgery first followed by postoperative orthodontic treatment. This method shortens overall treatment time, provides immediate aesthetic improvement, facilitates favorable orthodontic tooth movement, and may lead to earlier improvement in conditions such as obstructive sleep apnea. It is generally recommended for patients with mild anterior crowding, minimal transverse discrepancies, a flat or mild curve of Spee, and normally inclined incisors. Common surgical techniques include genioplasty, bilateral sagittal split osteotomy (BSSO), oblique ramus osteotomy, and Le Fort I osteotomy. Whenever possible, procedures are performed intraorally to avoid visible scarring.

Orthognathic surgery induces not only anatomical and functional changes but also psychological adaptations. Soft tissues, masticatory muscles, and the temporomandibular joint (TMJ) adapt to new skeletal relationships, contributing to improved facial balance and patient self-perception. However, there is currently no unified diagnostic algorithm to comprehensively evaluate postoperative anatomical, physiological, and socio-emotional changes. Emotional satisfaction, TMJ structural changes, muscle strength variations, sleep quality, and pain outcomes remain insufficiently studied.

The study proposes two hypotheses: the null hypothesis (H0) assumes no postoperative changes in TMJ anatomy, masticatory muscle strength, emotional response, facial pain, sleep quality, or depressive characteristics; the alternative hypothesis (H1) assumes that such changes do occur.

The objectives are to evaluate masticatory muscle strength and structure, TMJ anatomical changes, emotional state, depression and anxiety predisposition, sleep quality, facial pain, and aesthetic perception before and after surgery.

The study will include up to 100 patients undergoing bimaxillary orthognathic surgery (with or without genioplasty) at the Lithuanian University of Health Sciences Kaunas Clinics. Assessments will be conducted preoperatively, immediately postoperatively, and 3-6 months after surgery. Methods include CBCT imaging for TMJ evaluation, electromyography for masseter muscle strength, emotional analysis using the iMotions platform (facial expression analysis and electrodermal activity), and validated questionnaires (PHQ-15, HADS, VAS). Strict ethical standards will be followed in accordance with international guidelines, with informed consent obtained from all participants. No additional financial costs or conflicts of interest are declared.

The expected outcome is to determine correlations between anatomical, functional, psychological, and aesthetic changes following orthognathic surgery, providing a more comprehensive understanding of patient satisfaction and overall quality-of-life improvement.

Orthognathic surgery is the surgical treatment of one or both jaws by osteotomy of the bones in order to correct the malalignment/abnormal shape of the jaws, to restore their relationship to the central occlusion, thus restoring a correct bite and restoring the correct facial shape.

Individuals with dentofacial abnormalities struggle with biting and chewing, social interactions, and peer pressure to alter their look. Due to these difficulties, these people may suffer from psychological issues and see a marked decline in their quality of life.

Orthognathic surgery is a specialized procedure that must be carried out with orthodontic treatment. This means that before and after the surgical intervention, orthodontic care is essential to align the teeth and jaws, ensuring optimal results properly. The combination of these treatments helps correct misalignments, improve bite function, and enhance facial aesthetics. Without orthodontic preparation and follow-up, the surgical correction alone would not be as effective in achieving a stable and harmonious outcome.

Conventional approach

The term "orthodontic first approach" refers to the conventional method used in treatment, where orthodontic procedures are initiated before any surgical intervention. To achieve a stable surgical occlusion and overcome postoperative occlusal instability, preoperative orthodontic therapy is carried out before orthognathic surgery to realign the maxilla and mandible and to disclose the true skeletal disparity before surgery. The attractive profile of the face and the function of the teeth gradually deteriorate throughout the preoperative phase due to dental decompensation. Preoperative orthodontic therapy has the major disadvantage of being time-consuming. It typically takes 12 to 24 months, but depending on the complexity of the patient's initial oral condition, it may take up to 48 months.

Surgery-first approach

The surgery-first technique refers to an approach in which orthognathic surgery is performed first, followed by postoperative orthodontic therapy, without the need for preoperative orthodontic treatment. The modified surgery technique is used when the preoperative orthodontic treatment duration is reduced to less than six months. The benefits of the surgery-first method includes a reduction in the overall duration of treatment, a favorable postoperative orthodontic direction (which is the same as the direction of natural compensation), early facial aesthetic improvement, and early obstructive sleep apnea correction.

The surgery-first strategy is typically recommended for patients who require less prior care, such as those with:

1. well-aligned to mildly crowded anterior teeth;
2. a flat to mild curve of Spee;
3. normal to mildly proclined or retroclined incisors;
4. a minimal transverse discrepancy.

These days, genioplasty, bilateral sagittal split osteotomy (BSSO) of the mandible, oblique ramus osteotomy of the mandible, and Le Fort I osteotomy of the maxilla are the most commonly performed surgical procedures for correcting dentofacial abnormalities, with some variations. For optimal safety, jaw osteotomies should be performed through an intraoral approach whenever possible. This technique helps prevent facial scarring while ensuring adequate exposure of the skeletal structures. Important structures need to be maintained, and postoperative nutrition needs to be taken into account.

Orthognathic surgery affects many changes that occur in the human body and even the psychological aspects of a patient's personality.

The shape and appearance of the face are not corrected, as during orthognathic surgery the soft tissues, masticatory muscles, and the temporomandibular joint (TMJ) adjust/adapt to the changed bone positions and the altered bite and inter-maxillary relationships, thus correcting and creating a balanced facial appearance/contour that allows the person to feel more complete and emotionally attractive to themselves.

Medical research has not yet developed a unified diagnostic and assessment algorithm to fully evaluate post-operative changes after orthognathic surgery. The socio-emotional component and emotional satisfaction of patients after these operations have not been assessed. Physiological changes in the masticatory muscles and the TMJ after surgery are not assessed. Post-operative emotional and physiological pain was not assessed.

HYPOTHESIS

H0: Following orthognathic surgery, patients will not experience any changes in their temporomandibular joint anatomical structures, masticatory muscle strength, emotional response, facial pain, sleep quality before or after the procedure, or depressed characteristics.

H1: Following orthognathic surgery, patients will experience changes in their temporomandibular joint anatomical structures, masticatory muscle strength, emotional response, facial pain, sleep quality, before or after the procedure, or depressed characteristics.

OBJECTIVES

1. To assess the strength of patients' masticatory muscle contraction and their structures before and after orthognathic surgery.
2. To assess the predisposition to depression and anxiety in patients scheduled for orthognathic surgery and the reasons for the onset or disappearance of these predispositions.
3. To determine and assess the quality of sleep before and after surgery.
4. To assess the emotional state of patients on the I-Motions platform before and after surgery.
5. To assess post-operative acute and chronic pain with the Visual Analogue Scale (VAS) and the I-Motions platform to determine its origin.
6. To evaluate the postoperative changes in the temporomandibular joint (TMJ) anatomic structures in terms of their significance for the success of the surgery, the patient's overall life satisfaction, aesthetics, and the occlusal relationship.

MATERIALS and METHODS

Study design

Following the approval of the Ethical Committee of LSMU Kaunas Clinics' Center and the National Ethical Committee of Lithuania, informed consent was obtained from each patient enrolled in the study. Initially, a comprehensive patient evaluation was conducted (as detailed below) for individuals undergoing orthognathic surgery, including mandibular, maxillary, or bimaxillary procedures, with or without genioplasty. Subsequently, a postoperative evaluation was performed. The study aims to enroll up to 100 patients.

After the first phase of orthodontic treatment the patient will be reevaluated and CBCT scan will be performed for the planning of orthognathic surgery. Main surgeon which performs all orthognathic surgical procedures according to his license will evaluate all CBCT scans. CBCT scan is minimally invasive for patient health and it is required in all steps of the surgery. By performing this study no extra scans will be done.

One day before the orthognathic surgery:

1. Patients will fill in the General Data Questionnaire (gender, age, education, etc.);
2. A non-invasive study using electromyography on the i-Motions platform for emotional assessment (i-Motions 8.2, i-Motions A/S, Copenhagen, Denmark) will be implemented. This equipment uses an integrated artificial intelligence-based facial expression analysis algorithm (Affdex 4.0, Affectiva, Boston, USA) and electrodermal activity modules (Shimmer3 GSR, Shimmer, Dublin, Ireland) to provide a detailed and comprehensive characterization of the respondents' emotional state and the physiological galvanic skin response.
3. A non-invasive study using electromyography for m.masseter straight evaluation will be implemented with i-Motions platform;
4. Patients will fill Patient Health Questionnaire-15 (PHQ-15) for assessing somatic symptoms severity;
5. Patients will fill Hospital Anxiety and Depression Scale (HADS) for assessing depression and anxiety symptoms;
6. Facial aesthetics will be assessed.
7. Visual Analogue Scale (VAS) for preoperative pain in masticatory system.

After the orthognathic surgery:

1. Visual Analogue Scale (VAS) will be performed.
2. A CBCT scan will be performed.

After soft tissue recovery (3-6 months):

1. A non-invasive study using electromyography on the i-Motions platform for emotional assessment will be performed again;
2. A non-invasive study using electromyography on the i-Motions platform for m.masseter strength;
3. Patient Health Questionnaire-15 (PHQ-15) for assessing somatic symptoms severity;
4. Hospital Anxiety and Depression Scale (HADS) for assessing depression and anxiety symptoms;
5. Facial aesthetics assessed.
6. CBCT scan for TMJ anatomic/bone structures area changes evaluation.

Population

In Europe, including Lithuania, there is a lack of statistical data regarding the number of orthognathic surgeries performed; therefore, it is not possible to determine the exact number of potential subjects. This study aims to recruit the maximum feasible number of participants.

The study includes patients of Lithuanian University of Heath Sciences Kaunas Clinics Department of Maxillofacial surgery according to the following diagnoses in the internal register of Kaunas Clinics who are planned to undergo orthognathic surgery:

K07.0 Major abnormalities of jaw size; K07.1 Abnormalities of the relationship between the jaws and the base of the skull; K07.2 Abnormalities of the dental arch relation; K07.4 Malocclusion, unspecified; K07.5 Functional disorders of teeth and face; K07.8 Other anomalies of teeth and face; K07.9 Anomaly of teeth and face, unspecified;

The criteria for subject selection are as follows. The inclusion criterion is patients undergoing scheduled bimaxillary surgery with or without genioplasty, ASA 1 or 2. The exclusion criteria are: refusal to participate in the study, patients scheduled for bimaxillary surgery together with another complementary surgical procedure (such as rhinoplasty, blepharoplasty), age < 18 years, reinterventions, urgent surgeries, allergies to local anesthetics, allergies to anti-inflammatories, allergies to opioids, pregnant women, patients with diagnosed anxiety and depression, taking medication.

Intervention After the initial orthodontic treatment, orthognathic surgery is planned. One of the phases of the planning process is a CBCT scan. We will use CBCT scan to evaluate the anatomical structures of the TMJ.

One day before surgery, the patient will be asked to fill with the General Data Questionnaire, PHQ-15, HADS, a non-invasive study using electromyography on the iMotions platform for emotional assessment, electromyography for m.masseter straight and weight evaluation, facial aesthetics evaluation, VAS.

After the orthognathic surgery VAS will be performed again, a CBCT scan will be performed to evaluate operation.

After soft tissue recovery (3-6 months): electromyography on the iMotions platform for emotional assessment and m.masseter strength, PHQ-15, HADS, facial aesthetics evaluation, CBCT scan for TMJ anatomic/bone structures area changes evaluation.

Ethics

Prior to making a decision regarding participation in the study, all necessary information will be provided to each patient.

The information disclosed will be in strict accordance with the ethical principles outlined in the Declaration of Helsinki (latest revision at the 64th General Assembly, Fortaleza, Brazil, October 2013) and the International Council for Harmonisation Good Clinical Practice (ICH-GCP) Guidelines.

Before the commencement of the study, formal approval will be obtained from the Lithuanian Regional Ethics Committee for Biomedical Research.

The researcher will comprehensively outline the measures implemented to safeguard patient data and privacy, ensuring full compliance with European Directive 95/46/EC, the General Data Protection Regulation (EU) 2016/679, and Organic Law 3/2018 of December 5 on the Protection of Personal Data and the Guarantee of Digital Rights. Additionally, the researcher will elucidate the study's potential risks, inherent limitations, and the patient's right to withdraw at any stage without repercussions on their medical care or relationship with the research team.

Each patient will be provided with a detailed written information sheet and an informed consent document, accompanied by a verbal explanation. Written consent must be obtained before initiating any study-related procedures.

Financial report

This study is not subject to additional costs, since all the necessary data, software and surgical techniques are in the Lithuanian University of Heath Sciences Kaunas Clinics Department of Maxillofacial surgery and no additional procedures are introduced.

Disclosure of financial information

• The researchers state that there is no financial transaction involved in the study;
• The authors declare not to have any interest conflicts.

Expected results

By utilizing a novel algorithm, the I-Motions platform, and validated questionnaires, this study aims to analyze the correlation between depression, anxiety, and perceived changes in appearance before and after orthognathic surgery. The primary objective is to assess patient satisfaction, psychological and lifestyle changes, factors influencing the decision to undergo orthognathic surgery, and alterations in anatomical structures, including the masticatory muscles and TMJ, sleep quality and emotional response.

Inclusion Criteria:

• Patients treated at the Lithuanian University of Health Sciences (LSMU) Kaunas Clinics Department of Maxillofacial Surgery.
• Diagnosed according to the internal registry of Kaunas Clinics with one of the following ICD-10 codes:

K07.0 - Major abnormalities of jaw size K07.1 - Abnormalities of jaw-cranial base relationship K07.2 - Abnormalities of dental arch relationship K07.4 - Malocclusion, unspecified K07.5 - Functional disorders of teeth and face K07.8 - Other dentofacial anomalies K07.9 - Dentofacial anomaly, unspecified

• Scheduled to undergo planned orthognathic surgery.
• Classified as American Society of Anesthesiologists (ASA) physical status I or II.
• Age ≥ 18 years.
• Able and willing to provide written informed consent.

Exclusion Criteria:

• Refusal or inability to provide informed consent.
• Planned orthognathic surgery combined with additional elective surgical procedures (e.g., rhinoplasty, blepharoplasty, or other cosmetic procedures).
• Age under 18 years.
• Reinterventions or revision orthognathic surgery.
• Emergency surgical procedures.
• Known allergy to local anesthetics, anti-inflammatory drugs, or opioids.
• Diagnosed anxiety and/or depression requiring pharmacological treatment.
• Presence of psychiatric disorders classified under ICD-10 Chapter F (Mental and Behavioral Disorders).
• Pregnancy.