Maxillomandibular Advancement (MMA) Surgery Improves Obstructive Sleep Apnea: CAD/CAM vs. Traditional Surgery

Abstract

Obstructive sleep apnea (OSA) is a sleep-related breathing disorder characterized by a reduction or complete interruption of airflow during sleep, with episodes lasting at least 10 s. In severe cases, blood oxygen saturation can drop significantly, reaching levels as low as 40%. The aim of this study was to compare CAD/CAM-assisted maxillomandibular advancement (MMA) with traditional surgical techniques in the treatment of obstructive sleep apnea (OSA). We conducted a retrospective analysis of patients who underwent maxillomandibular advancement (MMA) for obstructive sleep apnea (OSA), all operated on consecutively by the same surgeon between 2022 and 2024 at the Maxillofacial Surgery of Policlinico Hospital San Camillo-Forlanini, Rome, Italy. This study included 18 patients with severe obstructive sleep apnea syndrome (OSAS) who underwent maxillomandibular advancement (MMA) surgery. The patients had a mean age of 38 years; 11 were male and 7 were female. Patients were divided into two groups: Group A, treated using a CAD/CAM-assisted surgical approach (five male and four female), and Group B, treated with conventional surgical techniques (six male and three female). Results: The comparison between preoperative and postoperative CT scans, along with 3D reconstructions using dedicated software, demonstrated a significant increase in airway volume following the skeletal repositioning. Notably, airway volume increased from 19.25 ± 0.5 mm³ to 26.14 ± 1.264 mm³ in group A and 20.564 ± 0.71 mm³ to 25.425 ±1.103 mm³ in group B. Conclusion: No significant differences were observed between the CAD/CAM-assisted and conventional surgical techniques for maxillomandibular advancement (MMA) in the treatment of severe obstructive sleep apnea (OSA). Both approaches led to a reduction in the apnea–hypopnea index (AHI) and an increase in posterior airway space (PAS). However, the use of software and digital planning through CAD/CAM technology allows for greater precision and shorter operative times, making the procedure more efficient overall.

1. Introduction

Obstructive Sleep Apnea (OSA) is a sleep-related breathing disorder characterized by recurrent episodes of partial (hypopnea) or complete (apnea) cessation of airflow during sleep, despite continued respiratory effort. These events occur due to relaxation of the pharyngeal muscles, which leads to the collapse of soft tissues in the posterior oropharynx, thereby obstructing the upper airway. This obstruction results in intermittent hypoxemia, sleep fragmentation, and repeated arousals, contributing to significant cardiovascular, metabolic, and neurocognitive consequences over time. This leads to partial reductions (hypopneas) and/or complete pauses (apneas) in breathing that last at least 10 s during sleep. Most pauses last between 10 and 30 s, but some may persist for 1 min or longer. This can lead to abrupt reductions in blood oxygen saturation, with SpO₂ falling to as much as 40 percent or more in severe cases [1].

In the third edition of the International Classification of Sleep Disorders (ICSD-3), obstructive sleep apnea (OSA) is categorized under sleep-related breathing disorders and is further subdivided into two distinct forms: adult OSA and pediatric OSA [2].

Obstructive sleep apnea (OSA) can be distinguished from central sleep apnea (CSA), which represents a separate category of sleep-related breathing disorders. While OSA is characterized by continued respiratory effort despite airflow limitation due to upper airway obstruction, CSA is defined by a temporary cessation of both airflow and respiratory effort, resulting from impaired central respiratory drive [3]. According to current literature and the third edition of the International Classification of Sleep Disorders (ICSD-3), the prevalence of obstructive sleep apnea syndrome (OSAS) in the general adult population is estimated to be approximately 13% in men and 6% in women. Epidemiological data suggest that over 1 billion individuals worldwide may be affected by some form of OSA, making it one of the most prevalent chronic disorders globally [1]. In addition, the prevalence of OSAS in the general adult population is estimated to range between 9% and 38%, depending on diagnostic criteria, population characteristics, and study methodology. Despite its high prevalence, it is estimated that approximately 80–90% of individuals with OSAS remain undiagnosed, representing a significant public health concern due to the associated cardiovascular, metabolic, and neurocognitive risks [4,5,6].

Several anatomical and physiological factors contribute to the pathogenesis of OSA. Among the most significant are obesity, advanced age, reduced upper airway muscle tone, and genetic predisposition. Structural anomalies of the craniofacial skeleton, such as retrognathia, micrognathia, mandibular hypoplasia, and a high-arched palate, are recognized contributors to upper airway collapsibility during sleep [7]. The most prevalent symptom of OSA is excessive daytime sleepiness, which results from repeated sleep fragmentation and intermittent hypoxemia during the night. In addition to hypersomnolence, patients frequently report morning headaches, difficulty concentrating, depressive symptoms, persistent fatigue, nocturia, and nocturnal gastroesophageal reflux.

Clinically, individuals with OSA often present with a characteristic pattern of morning drowsiness, daytime tiredness, and a tendency to fall asleep during sedentary activities, such as reading, watching television, or driving. These symptoms reflect the cumulative impact of disrupted sleep architecture and impaired restorative sleep. Patients with obstructive sleep apnea typically exhibit short sleep latency, but are often awakened 1–4 times during the night. Other common symptoms include morning headache and fatigue. Most individuals with OSA snore, and snoring combined with excessive daytime sleepiness is a frequent reason why patients seek medical evaluation through sleep studies [7].

Different questionnaires are available for assessing the risk of OSA, the main ones being the Berlin Questionnaire [8]; the STOP-Bang questionnaire, commonly used for screening in the preoperative setting; and the Epworth Sleepiness Scale [9], which, despite its low sensitivity for OSAS, remains an important tool for evaluating daytime sleepiness in both research and clinical practice [7]. With in-lab polysomnography being expensive and potentially inconvenient for patients, home sleep apnea testing (HSAT) is increasingly used, offering both high sensitivity and specificity for the diagnosis of obstructive sleep apnea [7]. Although physical examination may reveal anatomical alterations such as tonsillar hypertrophy, macroglossia, elongated soft palate, turbinate hypertrophy, deviated nasal septum, or retrognathia, normal findings do not exclude the diagnosis of obstructive sleep apnea syndrome (OSAS) [4]. If the clinical evaluation is suggestive of obstructive sleep apnea syndrome, the patient should undergo diagnostic tests, the gold standard being laboratory-based polysomnography [10], which typically includes measures of airflow through the nose via nasal pressure and/or oronasal thermal flow; respiratory effort via thoracic and abdominal inductance bands; oxygen hemoglobin saturation by continuous pulse oximetry; snoring; sleep stage and arousal using electroencephalogram, electrooculography and chin electromyogram findings; cardiac rate and rhythm via electrocardiogram and leg movement via electromyography [7]. HSAT measures air flow, respiratory effort, oxygen saturation, and heart rate without staging sleep or detecting limb movements. According to the third edition of the International Classification of Sleep Disorders, the diagnosis of OSA is confirmed if the total number of obstructive events, recorded by a sleep study, is equal/greater than 15 per hour or equal/greater than 5 per hour in a patient with a positive anamnesis of one or more of the following signs and symptoms: sleepiness; non-restorative sleep; fatigue; insomnia; waking up breath holding, gasping, or choking; bed partner or other observer reporting habitual snoring, breathing interruptions or both during the patient’s sleep; and new diagnosis of hypertension, a mood disorder, cognitive dysfunction, coronary artery disease, stroke, congestive heart failure, atrial fibrillation or type 2 diabetes mellitus [11]. The severity of OSA is typically quantified using the Apnea–Hypopnea Index (AHI), which represents the number of respiratory events per hour of sleep. Mild OSA is defined by an AHI of 5 to 14.9, moderate OSA by an AHI of 15 to 29.9, and severe OSA by an AHI equal to or greater than 30 [12].

Several studies indicate that nearly half of adults with OSA also experience sleep bruxism, suggesting a significant overlap between the two conditions [13]. Some evidence shows a positive correlation especially in patients with mild to moderate OSA, where bruxism episodes may increase and possibly act as a protective reflex to reopen the airway after an apneic event [14].

The aim of this study was to compare CAD/CAM-assisted maxillomandibular advancement (MMA) with traditional surgical techniques in the treatment of OSA.

2. Materials and Methods

We conducted a retrospective analysis of patients who underwent maxillomandibular advancement (MMA) for obstructive sleep apnea (OSA), all operated on consecutively by the same surgeon between 2022 and 2024 at the Maxillofacial Surgery of Policlinico Hospital San Camillo-Forlanini, Rome, Italy. A dedicated informed consent form was developed for this study. All procedures were conducted in accordance with the ethical principles outlined in the Declaration of Helsinki.

The inclusion criteria were as follows:

• Severe or moderate OSA confirmed by polysomnography (AHI > 15).
• Multidisciplinary evaluation by the OSA team of our institution, maxillofacial surgeon, dentist, pneumologist, ENT surgeon, and bariatric surgeon, which proposed MMA.
• Drug-induced sleep endoscopy (DISE) was performed preoperatively to confirm the potential benefit of MMA through mandibular advancement maneuvers.
• Patients in good general health with no anesthetic contraindications for surgery (ASA ≤ 3).

The exclusion criteria were as follows:

• Pediatric patients, as well as those with respiratory diseases or specific craniofacial malformations.
• Patients with severe conditions that contraindicated general anesthesia (ASA ≤ 4).
• Patients with severe heart conditions.
• Presence of psychiatric disorders.
• Age under 18 years.
• Syndromic conditions.
• History of previous orthognathic surgery.
• Refusal to provide informed consent.

For each patient, demographic and clinical data were collected, including age, sex, and preoperative body mass index (BMI). Polysomnographic evaluations were conducted by the Pneumology Unit within six months prior to surgery and repeated six months postoperatively to assess treatment outcomes. Patients were divided into two groups based on the surgical technique used: one group underwent MMA using a CAD/CAM-assisted approach, while the other received traditional surgical treatment. Comparative analysis was performed to evaluate the efficacy of each method in improving OSA-related parameters.

This study included 18 patients with severe obstructive sleep apnea syndrome (OSAS) who underwent maxillomandibular advancement (MMA) surgery. The patients had a mean age of 38 years; 11 were male and 7 were female. Patients were divided into two groups:

• Group A: treated using a CAD/CAM-assisted surgical approach (5 male and 4 female);
• Group B: treated with conventional surgical techniques (6 male and 3 female).

In this retrospective study, patients were not assigned to groups through randomization. Instead, inclusion was based on a chronological review of medical records, proceeding in reverse order starting from December 2024. The first 9 consecutive patients treated with the traditional technique and the first 9 patients treated with the CAD/CAM technique were selected, in accordance with the sample size determined by the power analysis for each group.

Importantly, statistical analysis was performed by an expert biostatistician under blinded conditions, without knowledge of the treatment modality assigned to each patient. This approach was adopted to minimize the risk of bias in data interpretation and to ensure greater objectivity in the comparative analysis between the two groups.

For both groups, helical CT scans were acquired for virtual surgical planning, enabling the design of patient-specific cutting guides and fixation plates. Scans of the head and neck were performed with the patient in a supine position and the head in a natural posture. These imaging datasets, combined with occlusal records derived from digital dental models and clinical photographs, were used to generate a three-dimensional reconstruction of the craniofacial skeleton, accurately aligned with the patient’s natural head position. Preoperative and postoperative assessments included full-night polysomnography, performed within six months before surgery and repeated six months after the procedure. The following respiratory and oxygenation parameters were collected and analyzed:

Apnea–Hypopnea Index (AHI)

Apnea Index (AI)

Hypopnea Index (HI)

Mean Apnea Duration

Oxygen Desaturation Index (ODI)

Mean Oxygen Saturation (SaO₂)

Lowest Oxygen Saturation (Nadir SaO₂)

Mean Desaturation Events

Percentage of Time with SaO₂ < 90%

For patients of group A, the preoperative planning of MMA surgery was performed using Dolphin Imaging software 11.5 version (Dolphin Imaging & Management Solutions, Chatsworth, CA, USA), a validated digital platform widely adopted in craniofacial and orthognathic surgical workflows. This system enables three-dimensional cephalometric analysis, virtual surgical simulation, and high-fidelity prediction of postoperative outcomes.

Computed tomography scans and digital dental models were acquired and imported into the software. These datasets were used to assess skeletal discrepancies, upper airway morphology, and occlusal relationships. Virtual osteotomy simulations were then conducted to determine the required extent of maxillary and mandibular advancement, and to visualize the anticipated impact on the upper airway space.

This digital workflow allowed for precise customization of surgical movements and enhanced interdisciplinary communication. Furthermore, based on the virtual plan, patient-specific surgical guides were fabricated to ensure accurate execution of osteotomies as designed.

Le Fort I osteotomy and bilateral sagittal split osteotomies (BSSO) of the mandibular ramus were digitally planned. Virtual simulations of the maxillary and mandibular movements were performed, and both intermediate and final surgical splints were designed according to a maxilla-first approach. These splints were subsequently fabricated using 3D printing. Following virtual surgical planning, CAD/CAM technology was employed to create polyamide cutting guides tailored to the planned osteotomies, along with custom-made titanium fixation plates. Both the guides and plates were manufactured through 3D printing techniques (Figure 1). CT images were segmented to simulate osteotomies and evaluate the airway. Additionally, patient-specific cutting guides and fixation plates were designed as part of the surgical planning process using Dolphin Imaging surgical planning software.

For patients of group A, an intraoral incision was made in the upper vestibule, above the dental apices, extending from the right first molar to the left first molar. A mucoperiosteal flap was elevated to expose the maxillary bone. The bone-supported cutting guide was then positioned on the maxilla. Both cutting guides were secured in place using 2.0 mm screws. A Le Fort I osteotomy was performed using a piezosurgical device. The maxilla was then repositioned according to the preoperative plan and stabilized with custom-made titanium plates (Figure 1, Figure 2 and Figure 3). An incision was made in the vestibular mucosa of the mandible, extending from the first molar to the anterior region of the mandibular ramus along the oblique line. A mucoperiosteal flap was elevated to expose the lateral surface of the mandibular ramus, allowing identification of the inferior alveolar nerve. A tooth- and bone-supported cutting guide was then positioned, and a bilateral sagittal split osteotomy (BSSO) was performed using a piezosurgical device. The mandible was repositioned according to the preoperative plan and stabilized using titanium plates. All patients received antibiotic prophylaxis with bacampicillin, which was continued orally for six days postoperatively. Postoperative rehabilitation following surgery is a structured, multi-phase process aimed at restoring functional capacity, achieving occlusal stability, and supporting overall patient recovery.

Phase 1—First three Weeks Post-Surgery

The initial phase focuses on managing pain and edema. The protocol includes

Pharmacological therapy with analgesics and anti-inflammatory agents;

Liquid or semi-liquid diet, to minimize mechanical stress on osteotomy sites;

Functional rest and assisted oral hygiene, using antiseptic mouth rinses (e.g., chlor hexidine) to prevent infection and promote soft tissue healing.

Phase 2—Weeks 3 to 6

During this phase, gradual functional recovery begins:

Progressive reintroduction of mastication, starting with a soft diet and transitioning to solid foods based on occlusal stability;

Mandibular mobilization exercises, aimed at restoring mouth opening and closing movements;

Orthodontic follow-up, to monitor occlusal adaptation and address any misalignments.

Phase 3—Week 6 to 6 Months

The final phase is dedicated to comprehensive functional rehabilitation:

Consolidation of masticatory function and occlusal stability;

Neuromuscular coordination exercises, including speech and swallowing training when indicated;

Psychological support, if needed, to assist patients in adapting to changes in facial appearance and oral function.

In Group B, maxillary and mandibular osteotomies were performed without the use of surgical guides. However, in this group as well, splints were used to stabilize the maxillary and mandibular bone segments.

For both groups, anti-edema therapy was administered with dexamethasone for three days, and pain management was provided with ibuprofen.

Statistical Analysis

The sample size was determined using a validated clinical statistics tool (http://clincalc.com/stats/samplesize.aspx (accessed on 10 February 2022)), aimed at calculating the minimum number of cases required to detect a statistically significant difference in the improvement of the Apnea–Hypopnea Index (AHI). The calculation was based on a dichotomous outcome (presence or absence of new bone formation), assuming an effect incidence of 10% in the control group and 95% in the treated group. Under these parameters, the optimal sample size required to achieve adequate statistical power was estimated to be 8 patients. The experimental data has been collected and elaborated using GraphPad 9 software package (Prism, San Diego, CA, USA). The Kolmogorov–Smirnov test has been applied to test the normal distribution of the continuous variables followed by the Student t-test to evaluate the statistical significance among the variables investigated. The following continuous variables were considered prior to and after the treatment: snoring and apnea events, SaO₂, Nadir SaO₂, average desaturation and SaO₂ < 90% The Mann–Whitney test has been applied to evaluate the significance of the categorical data pre-treatment and post treatment including apnea–hypopnea index (AHI), apnea index (AI), hypopnea index (HI) and oxygen desaturation index (ODI). The intergroup comparisons and level of significance has been tested adopting the ANOVA followed by Tukey’s post hoc test for continuous variables and the Kruskal–Wallis test followed by Dunn’s post hoc test for categorial variables. The level of significance was considered for p value < 0.05.

3. Results

3.1. Group A

The comparison between preoperative and postoperative CT scans, along with 3D reconstructions using dedicated software, demonstrated a significant increase in airway volume following the skeletal repositioning. The airway volume increased from 19.25 ± 0.5 mm³ to 26.14 ± 1.264 mm³.

3.1.1. Continuous Variables

The snoring and apnea events calculated before treatment were, respectively, 70% ± 14.5 and 19 ± 7 events, while after the treatment the means were 0% and 1 ± 0.6. The SaO₂ before the treatment was 95 ± 2% and increased to 99 ± 1.2% after the treatment. In this way, a similar trend was reported considering the Nadir SaO₂ that increased from 81 ± 3.9% to 87 ± 3%. The average desaturation decreased from 8.2 ± 2.8% to 0% after the treatment. SaO₂ < 90% values observed prior to and after treatment were 6.7 ± 2.1% to 0%.

3.1.2. Categorial Variables

The Apnea–Hypopnea Index (AHI) and Apnea Index (AI) calculated prior to treatment were respectively 45 ± 12.5 and 28 ± 6.2, while after the treatment they were 3 ± 2.6 and 2 ± 0.7. The Hypopnea Index (HI) was 17 ± 6.4 prior to the treatment to 1 ± 0.6 at the follow-up. The oxygen desaturation index (ODI) decreased from 43 ± 27 to 2 ± 0.9 (

Table 1. Group A: Respiratory and oxygenation parameters were collected and analyzed before and after surgery.

	Group A		Group A		Group A
	Pre-Treatment		Post-Treatment
	Mean	DV	Mean	DV	p Value
Snoring	70%	(14.5%)	0%	(0%)	p < 0.01
AHI (Apnea–Hypopnea Index)	45	(12.5)	3	(2.6)	p < 0.01
AI (Apnea Index)	28	(6.2)	2	(0.7)	p < 0.01
HI (Hypopnea Index)	17	(6.4)	1	(0.6)	p < 0.01
Average apnea	19	(7.0)	6	(3.6)	p < 0.01
ODI (Oxygen desatur. Index)	43	(27)	2	(0.9)	p < 0.01
SaO2 average	95%	(2%)	99%	(1.2%)	p < 0.01
Nadir SaO2	81%	(3.9%)	87%	(3%)	p = 0.0031
Average desaturation	8.20%	(2.8%)	0%	(0%)	p < 0.01
SaO2 < 90%	6.70%	(2.1%)	0%	(0%)	p < 0.01

and Figure 5).

3.1.3. Cephalometric Changes Following Orthognathic Surgery

Cephalometric analysis revealed a significant improvement in sagittal skeletal relationships following orthognathic surgery. Specifically, the SNA angle increased from 77.56° ± 2.13 to 80.45° ± 1.13, indicating a forward repositioning of the maxilla. The SNB angle improved from 67.67° ± 2.00 to 75.00° ± 3.80, reflecting a substantial mandibular advancement. Consequently, the ANB angle decreased from 9.78° ± 1.31 to 4.90° ± 0.79, suggesting a marked correction of the sagittal skeletal discrepancy (Figure 4).

3.2. Group B

The comparison between preoperative and postoperative CT scans, along with 3D reconstructions using dedicated software, demonstrated a significant increase in airway volume following the skeletal repositioning. The airway volume increased from 20.564 ± 0.71 mm³ to 25.425 ±1.103 mm³. The following respiratory and oxygenation parameters were collected and analyzed before and after surgery (

Table 2. Group B: Respiratory and oxygenation parameters were collected and analyzed before and after surgery.

	Group B		Group B		Group B
	Pre-Treatment		Post-Treatment
	Mean	DV	Mean	DV	p Value
Snoring	72%	(14.4%)	0%	(0%)	p < 0.01
AHI (Apnea–Hypopnea Index)	43	(9.73)	2	(1.8)	p < 0.01
AI (Apnea Index)	30	(4.5)	3	(0.9)	p < 0.01
HI (Hypopnea Index)	13	(4.2)	2	(1.2)	p < 0.01
Average apnea	16	(5.4)	6	(4.5)	p < 0.01
ODI (Oxygen desatur. Index)	42	(19)	3	(1.5)	p < 0.01
SaO2 average	94%	(1.6%)	99%	(0.9%)	p < 0.01
Nadir SaO2	80%	(5.2%)	88%	(3.5%)	p = 0.0031
Average desaturation	8.40%	(3.7%)	0%	(0%)	p < 0.01
SaO2 < 90%	6.80%	(1.8%)	0%	(0%)	p < 0.01

).

3.2.1. Continuous Variables

The means regarding snoring and apnea prior to the treatment were 70% ± 14.4 and 16 ± 5.4, while post-treatment the means decreased to 0% and 6 ± 4.5. The SaO₂ assessed at the baseline was 94 ± 1.6%, increasing to 99 ± 0.85% after the treatment. Nadir SaO₂ increased from 80 ± 5.2% at the baseline to 88 ± 3.5%. The average desaturation decreased from 8.4 ± 3.7% at the baseline to 0% at the end timepoint. The SaO₂ < 90% values observed before and after treatment were 6.8 ± 1.8% to 0% respectively.

3.2.2. Categorial Variables

The Apnea–Hypopnea Index (AHI) and Apnea Index (AI) assessed at the baseline were respectively 43 ± 9.73 and 30 ± 4.5, while at the end timepoint they decreased to 2 ± 1.8 and 3 ± 0.9. The Hypopnea Index (HI) at the baseline was 13 ± 4.2, increasing to 2 ± 1.2 at the follow up. The Oxygen desatur. Index (ODI) decreased from 42 ± 19 to 3 ± 1.5 (Table 2 and Figure 5).

3.2.3. Cephalometric Changes Following Orthognathic Surgery

Cephalometric analysis revealed a significant improvement in sagittal skeletal relationships following orthognathic surgery. Specifically, the SNA angle increased from 77.67° ± 2. to 81° ± 1.23, indicating a forward repositioning of the maxilla. The SNB angle improved from 67.2° ± 1.9 to 75.20° ± 3.80, reflecting a substantial mandibular advancement. Consequently, the ANB angle decreased from 10° ± 1.2 to 5° ± 0.79, suggesting a marked correction of the sagittal skeletal discrepancy.

In the present study, no significant postoperative complications were observed among the included patients. Specifically, there were no cases of impaired bone healing or the development of oral or oroantral fistulas.

However, three patients, two from Group B and one from Group A, experienced transient lower lip paresthesia, likely related to surgical manipulation. In all cases, the sensory disturbance resolved spontaneously within approximately six months postoperatively.

Additionally, some patients exhibited a more pronounced postoperative edema compared to others. This variability in the postoperative course was effectively managed with standard medical therapy and did not result in any significant delays in healing or the need for additional interventions.

4. Discussion

The results of this retrospective study demonstrate that all analyzed parameters showed improvement following surgery. Notably, airway volume increased from 19.25 ± 0.5 mm³ to 26.14 ± 1.264 mm³ in group A and 20.564 ± 0.71 mm³ to 25.425 ± 1.103 mm³ in group B. In addition, significant improvements were observed in the following parameters in both groups without statistical difference: Apnea–Hypopnea Index (AHI), Apnea Index (AI), Hypopnea Index (HI), Mean Apnea Duration, Oxygen Desaturation Index (ODI), Mean Oxygen Saturation (SaO₂), Lowest Oxygen Saturation (Nadir SaO₂), Mean Desaturation Events and percentage of time with SaO₂ < 90%. The management of OSA includes medical and surgical interventions as well as behavioral measures, the latter being abstinence from alcohol, avoiding a supine sleep position, regular aerobic exercise and weight loss [15,16,17]. The use of Continuous Positive Airway Pressure (CPAP) is able to counter the collapse of the oropharynx during sleep and is considered the primary therapy for nearly all symptomatic patients suffering from mild to severe OSA, being able to normalize the AHI in more than 90% of cases [7]. CPAP remains the gold standard for OSA management, effectively reducing apnea–hypopnea index (AHI), improving daytime sleepiness, and lowering blood pressure and cardiovascular risk [18,19]. However, adherence rates to therapy are suboptimal, often ranging from 30% to 60%, and its impact on long-term cardiovascular outcomes remains variable. Another option to reduce upper airway collapsibility and increase the caliber of the oro-hypopharynx in patients with mild to moderate OSAS is the use of a Mandibular Advancement Device (MAD), which positions the mandible in a protruded state [20]. When patients are unable to tolerate medical devices such as the aforementioned, or when the reduction in AHI and symptoms is unsatisfactory, surgical intervention should be considered. Mandibular advancement devices (MADs) are recommended for patients with mild to moderate obstructive sleep apnea (OSA) or for those who are intolerant to continuous positive airway pressure (CPAP). Long-term use of MADs significantly reduces AHI and improves daytime sleepiness and blood pressure, with efficacy comparable to CPAP in selected populations [21,22]. According to the Stanford algorithm by Riley and Powell, sleep surgery is divided into phase I and phase II procedures. The first include soft tissue interventions such as nasal surgery (septoplasty, turbinate reduction, nasal valve surgery), tongue reduction, tonsillectomy, uvulopalatopharyngoplasty (UPPP), genioglossus advancement and hyoid myotomy (GAHM); phase II consists of maxillo-mandibular advancement (MMA) [23]. Maxillomandibular advancement (MMA) involves advancing the facial skeleton by at least 10 mm with a clockwise rotation, resulting in a stable increase in upper airway volume and a reduction in the apnea–hypopnea index (AHI). This effect is attributed to enhanced stability of the pharyngeal dilator muscles and increased space for the tongue [1,24]. Traditionally, Phase II surgery was reserved for cases in which Phase I procedures failed to produce clinically meaningful improvement. However, a revised Stanford protocol suggests that this should not always be the case. With the aid of drug-induced sedation endoscopy (DISE), it is possible to assess complete concentric collapse (CCC) of the velum and lateral pharyngeal wall collapse, the latter being particularly difficult to address with soft tissue procedures. Therefore, MMA should be considered as a first-line option in patients demonstrating severe or complete lateral pharyngeal wall collapse on DISE, regardless of their maxillofacial phenotype. Furthermore, other indications for Phase II surgery preceding Phase I procedures include patients with OSAS and concurrent dentofacial deformity and patients with moderate to severe OSAS without dentofacial deformity but presenting with a low hyoid position, obtuse cervicomental angle, and high occlusal plane inclination. Nonetheless, patients should be advised that medical interventions and/or Phase I surgery may still be necessary to achieve full management of OSAS [25,26]. A newer therapeutic approach for OSAS is hypoglossal nerve stimulation (HNS), which aims to increase the tone of the pharyngeal dilator muscles during sleep. This is achieved through the implantation of electrodes around the hypoglossal nerve, which are activated in synchrony with respiratory effort, thereby promoting airway patency and reducing upper airway collapsibility [27]. Surgery, including uvulopalatopharyngoplasty (UPPP), maxillomandibular advancement, and other upper airway procedures, is reserved for patients who cannot tolerate CPAP or oral appliances [28,29].

MMA is an invasive surgical option for OSA, primarily indicated in patients who are unable to tolerate non-surgical therapies and in those who have shown refractoriness to other surgical interventions. MMA achieves enlargement of the nasopharyngeal, retropalatal, and hypopharyngeal airway by physically expanding the facial skeletal framework via Le Fort I maxillary and sagittal split mandibular osteotomies. Advancement of the maxilla and mandible increases tension on the pharyngeal soft tissues, thereby enlarging both the mediolateral and anteroposterior dimensions of the upper airway.

Paulo Alceu Kiemle Trindade et al. [30] evaluate the effectiveness of maxillomandibular advancement surgery in the treatment of Obstructive Sleep Apnea by comparing the pre- and postoperative Apnea and Hypopnea Index, with a mean percentage reduction in the Apnea and Hypopnea Index of 79.5% after surgery. The meta-analysis was in favor of the intervention, characterizing maxillomandibular advancement surgery as an effective treatment for obstructive sleep apnea in adults [8]. MMA consistently leads to substantial reductions in the apnea–hypopnea index (AHI), with mean reductions ranging from 79.5% to over 80%, and postoperative AHI values often falling below 10 events per hour [31]. Surgical success rates (defined as >50% reduction in AHI) range from 73% to 88%, with cure rates (AHI < 5) between 38% and 47% [32]. MMA physically enlarges the upper airway by advancing the maxilla and mandible, resulting in increased airway volume, improved oxygen saturation, and reduced airway collapse during sleep [33]. Most studies and meta-analyses report surgical success rates for MMA between 82% and 93%, with pooled estimates commonly around 85–86%. Success is typically defined as a ≥50% reduction in apnea–hypopnea index (AHI) and a postoperative AHI below 15 or 20 events per hour [34,35,36]. Long-term follow-up studies confirm that success rates remain high (up to 89%) several years post-surgery, with sustained improvements in AHI and quality of life [36]. Factors associated with increased surgical success include younger age, lower preoperative weight and AHI, and greater maxillary advancement [37]. While complications such as temporary facial numbness can occur, MMA is generally considered safe and leads to improvements in quality of life and OSA symptoms, especially in patients with positive airway pressure therapy intolerance [38]. The findings presented in this study are consistent with those previously reported in the scientific literature, confirming the effectiveness and reliability of MMA. This further supports the validity of existing evidence and contributes to the growing of knowledge on MMA and OSA. However, it must be acknowledged that the retrospective design of this study entails several inherent limitations, including the risk of selection bias, the absence of randomization, and reliance on the quality and completeness of recorded data. Furthermore, the observational nature of the study restricts the ability to establish definitive causal relationships between the variables analyzed. Despite these constraints, the findings provide valuable insights and serve as a solid foundation for future prospective studies with controlled designs. No statistically significant differences were observed between the groups for any of the parameters considered. However, the integration of digital technologies into maxillofacial surgery has significantly enhanced the accuracy, efficiency, and predictability of surgical procedures. Among these innovations, CAD/CAM systems have emerged as essential tools, enabling clinicians to streamline workflows and achieve reproducible and predictable outcomes. The rationale for employing CAD/CAM technology lies in its ability to minimize human error, ensure reproducibility, and facilitate the fabrication of restorations with high dimensional precision. In our study, CAD/CAM technology was specifically utilized to improve surgical accuracy. The use of this technology entails an increase in direct costs associated with virtual planning, the production of patient-specific surgical guides, and the use of dedicated software platforms. However, these additional expenses may be partially offset by several clinical and logistical advantages, including reduced operative time; enhanced precision in both planning and execution; lower incidence of complications and reduced need for surgical revisions. In high-volume centers or specialized referral units, the initial investment in CAD/CAM systems may be justified by an overall improvement in procedural efficiency and resource optimization.

The learning curve associated with CAD/CAM implementation is generally steep during the initial phase. Nevertheless, it tends to plateau rapidly due to the intuitive nature of the software interfaces and the standardization of digital workflows. A multidisciplinary integration, encompassing the surgeon, orthodontist, biomedical engineer, and dental technician, is essential to fully exploit the potential of this technology and to ensure optimal clinical outcomes. Although no significant differences have emerged in terms of clinical outcomes, the CAD/CAM surgical approach stands out for its greater operational simplicity and, in some cases, for a reduction in procedural time compared to traditional surgery.

5. Conclusions

No significant differences were observed between the CAD/CAM-assisted and conventional surgical techniques for maxillomandibular advancement (MMA) in the treatment of severe obstructive sleep apnea (OSA). Both approaches led to a reduction in the apnea–hypopnea index (AHI) and an increase in posterior airway space (PAS). However, these results should be interpreted with caution. The retrospective design of the study and the limited sample size do not allow for definitive conclusions regarding the overall efficiency or superiority of the CAD/CAM system compared to conventional methods.