A review on the influence of rapid maxillary expansion and mandibular advancement for treating obstructive sleep apnea in children

4.1 Types of Apneas

Apnea is usually classified as central, obstructive or mixed. In central apnea, the air passage is absent due to insufficient respiratory effort [29]. In obstructive apnea, airflow is not present despite constant respiratory effort due to upper airway obstruction [29]. In mixed apnea, central and obstructive apnea occur successively with no normal breathing between the events [29]. It is important to emphasize that there are differences between pediatric OSA and OSA in adults. For instance, OSA in children can cause behavioral problems, while OSA usually manifests as daytime somnolence in adults [8].

4.2 Signs and symptoms

Some common signs of enlarged tonsils and adenoids include maxillary compression, a thin nasal cavity associated with a deep palate and posterior crossbite [8, 30]. Similarly, an atypical orofacial growth pattern known as adenoid facies was also reported [19]. OSA has been associated with several daytime and nocturnal symptoms [29]. The diurnal ones involve excessive drowsiness and abnormal behaviors such as aggressiveness, hyperactivity, or, in contrast, social isolation and pathological shyness. They may present as repetitive upper respiratory infections and headaches [29]. Comparatively, nocturnal symptoms include enuresis, nightmares, intense sweating, snoring and episodes of apnea that impede the normal sleep cycle and hinder its restorative function [29, 31]. Fatal consequences can occur in the most severe cases of OSA due to cardiorespiratory failure caused by the disease [15].

4.3 Apnea Hypopnea Index

AHI is the main diagnostic criterion of OSA. It is defined as the number of apnea and hypopnea events recorded per hour of sleep [15]. AHI is obtained by PSG examination and is based on the following criteria:

In adults, none/minimal: AHI <5 per hour; mild: AHI ≥5, but <15 per hour; moderate: AHI ≥15, but <30 per hour, and; severe: AHI ≥30 per hour [32]. In children, none: AHI <1 per hour; mild: AHI 1–4 per hour, moderate: AHI 5–9 per hour, and; severe: AHI ≥10 per hour [9]. AHI results allow the severity assessment of symptoms, estimate the potential risk of complications over time, and help to guide appropriate treatments [30].

4.4 Diagnostic methods

The diagnosis of OSA is based on the data obtained from laboratory studies, physical examinations, and medical history [11, 29]. The gold standard for diagnosing OSA is PSG [28], consisting of channels for electromyography, electroencephalography, electrocardiography, electrooculography, nasal and oral airflow, chest and abdominal movements, pulse oximetry, carbon dioxide tension and arterial oxygen saturation [14, 29]. PSG provides important data on some parameters related to sleep, including time spent below a certain level of oxygen saturation during the night, number and duration of complete or partial obstructions per hour of sleep, lowest oxygen saturation during each event, presence of arrhythmias, type of heart failure, presence and severity of respiratory disorders, and their impact on the cardiovascular system [29]. It also provides data on the severity of sleep disruptions [29].

4.5 Continuous Positive Airway Pressure

The constant use of CPAP improves symptoms, evidenced by improvement in PSG results in up to 85% of OSA patients. However, potential adverse events include blocked nose, dry mouth and an increased number of awakenings [33].

CPAP consists of using small machines that direct the insufflated air through a tube and a mask placed over the pediatric patient’s nose or nose and mouth. Air is then directed towards the back of the pharynx [33] to keep the airway patent and facilitate optimal breathing [8]. However, children may have difficulties adhering to this treatment as they could develop intolerance [15, 26] and non-compliance [34, 35]. Its use in pediatric patients is limited due to concerns associated with growth abnormalities [33] and the risk of developing maxillary retrognathia over time [10, 36]. Some professionals have described the use of forehead-supported masks to mitigate the negative effects of backward pressures on the face [24].

OAs are often preferred over CPAP. However, OAs may cause residual OSA [37], an issue also observed with CPAP therapy, because many patients either reject treatment outright or only partially tolerate it [38].

4.6 Surgical treatment

Surgery aims to widen the airway by removing the cause of its obstruction after determining exactly where it occurs [39]. The excess tissue is usually located in the oropharyngeal tract in patients with OSA [39].

Adenotonsillectomy is not only used for children with OSA but is also recommended for patients with adenotonsillar hypertrophy [33]. This is the main anatomical risk factor for OSA [21]. Adentonsillectomy has been shown to reduce the severity of OSA in most children, evidenced by polysomnographic findings and quality of life changes [21]. Persistent residual OSA has been reported after surgery in 25% to 40% of children treated with adenotonsillectomy [33]. Maxillary constriction, mandibular retrusion, a narrow upper airway and a long narrow face are craniofacial morphological characteristics often observed in children who coincidentally have OSA and enlarged tonsils [21].

Uvulopalatopharyngoplasty is a surgical intervention that involves resecting the uvula, part of the soft palate and excess tissues in the oropharynx. It is usually performed simultaneously with tonsillectomy [39]. It is widely used as therapy for OSA in selected patients [39].

Some long-term complications include swallowing difficulties and dry throat. In addition, velopharyngeal insufficiency was also reported in up to one-third of the patients [39]. The success of surgery varies depending on whether it is performed alone (success rate, ~30%) or in conjunction with tonsillectomy (success rate, ~60%) [39].

More extensive surgical approaches can be used in craniofacial disorders when upper airway obstruction is severe such as tracheotomy [40]. Patients requiring this procedure often have neuromuscular disorders leading to hypotonia and severe craniofacial abnormalities [40]. Tracheotomy may also be used as a temporary measure to control severe OSA until another surgical procedure can be performed.

4.7 Oral Appliances

Over the last 10 years, oral appliances have gained increasing recognition as a useful alternative to CPAP [39]. OAs are a common therapy for OSA patients [39]. However, mild to moderate OSA cases can be influenced [31] by non-compliance to CPAP, although CPAP seems more efficient in the definitive treatment of OSA than OAs [6, 41, 42]. There are several factors associated with the therapeutic responses to oral appliance treatment, including differences in devices, treatment protocols and craniofacial and upper airway characteristics [37].

4.8 Rapid maxillary expansion

Candidates for RME are patients with dental crowding, narrow palates or high arches, posterior crossbite, and those with class II or III malocclusions [43]. The objective of RME is to expand the maxilla by separating the middle palatine suture due to the late fusion of its structure [43]. Although this procedure is successfully performed in prepubertal patients, there is great variability in clinical results, mainly in late adolescence and young adults, in whom this treatment could have unpredictable outcomes [43] because chronological age cannot be used as an indicator for determining the developmental stage of the midpalatal suture during growth in these patients [43].

Individual evaluation of the midpalatal suture morphology prior to RME is important. Angelieri et al. [43] proposed a methodology for individualized assessment of the midpalatal suture using cone beam computed tomography (CBCT) [43].

RME is performed in patients in stage A, where the midpalatal suture is almost a straight high-density sutural line with no or little interdigitation. It is also performed in stage B, where the midpalatal suture assumes an irregular shape and appears as a scalloped high-density line, with less resisting forces and more skeletal effects than when performed during stage C, in which the midpalatal suture appears as 2 parallel, scalloped, high-density lines that are close to each other and separated by small, low-density spaces in the maxillary and palatine bones [43]. On the other hand, it is important to highlight that, despite the greater sutural resistance to conventional RME in stage C, it is still possible to orthopedically widen the maxilla without surgical intervention. Stages A and B are typically observed up to 13 years of age. Comparatively, stage C occurs from 11 to 17 years old, although it may occasionally be observed in younger or older age groups [43].

Fastuca et al. [14] used an orthodontic appliance in the non-ossified mid-palatal joint to move the maxillary bones away using lateral pressure [14]. This eliminated the compression and increased the volume of the airway, allowing airflow [44]. Their device also caused expansion and flattening of the palatine arch with an inferior direction of the maxilla and a change in the alignment of the jaw [45]. During RME, there is a reduction in nasal resistance, allowing air through the nose and improving the respiratory condition [45]. RME increases the arch of the upper jaw, which favors the position of the tongue, provides the seal of the lips when the mouth is closed and widens the oropharyngeal space, resulting in a significant reduction in oral breathing [45].

In the study by Fastuca et al. [14], the authors reported an increase of ~45% in the transverse nasal area after expansion. However, considering the V-shaped anatomy of the palate of the palatal suture, an increase in respiratory quality as the sole purpose of treatment is not considered an indication for RME [14]. Eichenberger et al. [46] reported that in people with normal occlusion, RME could be the last alternative to consider when other therapies have failed or have not shown satisfactory results [46].

Comparatively, Cabrera et al. [30] showed a significant improvement in the quality of life of the patients regardless of the severity of their respiratory obstruction and a decrease in OSA symptoms after RME therapy, which were evinced by the results of the PSG [30]. Similarly, Ashok et al. [47] concluded that maxillary narrowing was associated with chronic nasal obstruction and that RME could have a key role in alleviating the obstruction [47].

In a systematic review and meta-analysis by Camacho et al. [48], the authors found that RME led to a 50% decrease in AHI, producing an improvement in symptoms associated with pediatric OSA following an approximate 3 years of follow-up. Similarly, Bahammam et al. [32] reported a 77% reduction in AHI between pre-and post-RME (from 12.05 ± 5.06 to 2.6 ± 1.96) in a follow-up of less than 3 years [32], and after a follow-up ≥3 years, they observed that the improvement in AHI between pre-and post-RME was 73% (from 8.46 ± 7.82 to 3.2 ± 2.62) [32].

Marklud et al. [49] discussed the efficiency of OAs over time and expressed that they remained stable for up to 10 years but could be reduced over time [49]. The progression of OSA affects AHI [49]. Efficacy is affected and reduced because patients do not adhere to therapy due to insufficient subjective effects or potential adverse events during OSA follow-up [49]. Pirelli et al. [50] prospectively evaluated the effectiveness of RME in OSA pediatric patients using several clinical records of otorhinolaryngology, orthodontics and questionnaire scores annually over a 12-year follow-up period [50].

In a systematic review and meta-analysis by Tabrizi et al. [51], the authors assessed AHI before and after RME therapy following the treatment of pediatric OSA. They concluded that the mean difference was 6.37 events/hour (95% CI: 6.02–6.72), which was statistically significant (p = 0.00) before and after RME. Sanchez et al. [31] conducted a systematic review of the literature and a meta-analysis to analyze the results of RME on AHI and obtained similar data, with a mean reduction of 5.79 events/per hour [31]. Similarly, Camacho et al. [48] assessed the data obtained from sleep analysis in pediatric patients who underwent RME for OSA and reported that AHI was reduced from 8.9 events/per hour to 2.7 events/per hour in a follow-up of less than 3 years [48].

4.9 Mandibular advancement

Mandibular advancement has been used for several years to solve malocclusion issues [52] as a therapy for pediatric OSA. There is an increasing number of candidates for MAA with Class II and Division 1 mandibular retrusion malocclusions, which often reflect an imbalance or disharmony between the maxilla and mandible, typically due to the underdevelopment of the mandible and/or overdevelopment of the maxilla; thus, leading to a convex soft tissue profile [53].

The purpose of mandibular advancement is to modify the retrognathic mandibular position and redirect its development toward a more frontal position [28, 53, 54]. In addition, it increases the size of the upper airway through OAs that come in different forms, such as orthopedic, orthodontic, removable, and fixed OAs, thereby reducing the risk factors for OSA [13, 52, 53]. From an orthodontic point of view, they can modify the neuromuscular forces in the craniofacial skeleton and dentition, leading to a series of dentoalveolar and skeletal modifications [18, 25, 29].

The use of OA in patients with skeletal Class II jaw showed an increase in the upper airway dimensions, which persisted even after the cessation of facial growth [30].

MAAs represent an efficient therapeutic option for patients with mild-to-moderate OSA before the age of 13 years [53]. However, a treatment period of at least 6 months before the end of the pubertal growth spurt is required for a noticeable and constant change in mandibular development. The 6-month treatment was shown to have better results than a short-term treatment [53].

The need for mandibular advancement depends on the degree of overjet [52]. A literature review showed that mandibular advancement varies from 3 to 7 mm. When the overjet is reduced, the measurement is recorded by locating the incisors in an edge-to-edge relationship. However, in a larger overjet, the incisor relationship is recorded in two or three stages, bringing the mandible 4 mm forward in each stage and creating more orthopedic variability, which typically presents a positive change in airway permeability [52].

Regarding the variation in AHI, some studies have shown that regardless of the various treatments and procedures performed, there is a reduction in AHI after therapy. One study suggested that MAAs reduced AHI [52]. In a systematic review by Carvalho et al. [29], the authors reported that a clinical trial demonstrated a reduction of at least 50% in AHI in 23 patients with an acrylic resin oral bite plate for mandibular positioning compared with those without treatment [29]. Similar results were obtained in a systematic review by Nazaralli et al. [25], in which they suggested that MAAs had positive effects on AHI scores in a short period of time; however, it was not possible to deduce the efficiency of MAAs in the treatment of OSA in children [25].

In a systematic review by Tabrizi et al. [51], the effects of Twin Block, Two acrylic plates, Herbst and Modified monobloc were assessed on AHI compared with a control group. They found a mean of −1.79 events/per hour (95% CI: −2.10; −1.48) with a statistically significant difference (p = 0.000) between the two groups; however, the heterogeneity, I² , was 46%, indicating no significant difference between the two groups (p = 0.16), while the mean difference in AHI effects of MAA before and after OSA treatment in children was 1.84 events/per hour (95% CI 1.60–2.07; p = 0.000) in six studies and the heterogeneity between studies was statistically significant (p = 0.000) [51]. Similarly, Yanyan et al. [53] found a significant mean difference in AHI variation for the mandibular advancement group compared to the control group was −1.75 events/per hour (95% CI: −2 .07–1.44; p = 0.00001) [53].