Snoring and Obstructive Sleep Apnea in Children with Class II Skeletal Malocclusion: Efficacy of Twin Block Management

Abstract

Pediatric obstructive sleep apnea is an increasing major public health concern worldwide, partly resulting from the obesity epidemic which has encroached into the pediatric population. Individuals with a Class II skeletal malocclusion may suffer from snoring due to a retrognathic position of the mandible resulting in a restricted posterior pharyngeal airway space thus resulting in snoring and obstructive sleep apnea. This sleep pathology carries devastating health consequences resulting in daytime fatigue, hyperactivity and finally resulting in poor performance at school. Orthodontic therapy at an early age in OSA children may be effective in improving upper airway patency and alleviating symptoms of OSA. The twin block appliance was advocated as an efficient oral appliance for the treatment of children with OSA and mandibular retrognathia. The purpose of this chapter is to study the impact of twin block management on respiratory and biochemical parameters of Class II malocclusion children with OSA.

1. Introduction

The oral cavity, pharynx, and larynx represent upper airway anatomic structures that are responsible for swallowing, respiration, and articulation in humans. In children, the growth and development of the head and neck will affect the anatomy and physiology of the upper airways. Upper airway patency is controlled by several interrelated mechanisms. These include pharyngeal collapsibility, respiratory muscles, and tone of pharyngeal muscles. Sleep-disordered breathing (SDB) is a sleep disturbance with a broad spectrum of signs and symptoms. The pathology may range from habitual snoring to severe obstructive sleep apnea with gas exchange abnormalities. SDB is clinically characterized by snoring and physiologically by increased upper airway resistance and partial or complete upper airway obstruction which may affect respiration and negatively impact sleep quality [1]. The first evidence about sleep disturbance was probably addressed by Charles Dickens in his famous comic narrative The Posthumous Papers of the Pickwick Club. “The fat boy Joe was snoring heavily, he was falling constantly asleep and was described as having slow perception. Damn that boy…!” [2].

Apnea/hypopnea index (AHI) is the most important parameter in defining the severity of OSA. AHI is the number of apneas and hypopneas per hour of total sleep time. Apnea happens when the drop in the peak airflow is ≥90% of the pre-event baseline, with two breaths stopping at least during baseline respiration. This is usually associated with the presence of respiratory effort throughout the entire period of absent airflow [3]. On the other hand, hypopnea happens when the drop in peak airflow is ≥30% of pre-event baseline, with two breaths stop at least and either ≥3% oxygen desaturation or arousal [4]. In children, AHI greater than 1 event per hour is considered abnormal in the pediatric population [5, 6]. However, Diagnostic criteria for OSA is defined as an apnea-hypopnea index (AHI) of 5 or greater events per hour on nocturnal PSG and evidence of disturbed sleep, daytime sleepiness, or other daytime symptoms and thus, the severity of OSA is classified according to AHI as follow [7]: Mild OSA: AHI of 5–15, moderate OSA: AHI of 15–30, severe OSA: AHI of more than 30 event/hour.

2. Epidemiology

There is a wide variation in the prevalence of SDB due to inconsistency in the definition of the disease used by different studies. In their meta-analysis of the prevalence of SDB, Lumeng and Chervin conducted a comprehensive analysis of 48 international articles, encompassing research from regions across the globe, such as the United States, Europe, Asia, the Middle East, and Australia. Their findings indicated that the overall occurrence of snoring in children, as reported by parents using various criteria, stood at 7.45%. Meanwhile, parental accounts of apnea ranged from 0.2–4%. Additionally, they observed that the prevalence of sleep-disordered breathing (SDB) identified through parental responses on questionnaires fell within a range of 4–11%. Furthermore, studies using diagnostic polysomnography revealed that obstructive sleep apnea (OSA) prevalence was approximately 1–4%, as reported in the majority of investigations [7].

In numerous studies conducted within the United States, findings have indicated varying prevalence rates of sleep-disordered breathing (SDB) across different racial groups. African American children have been reported to exhibit a higher prevalence of SDB compared to their Caucasian counterparts, while Asians, when matched with Caucasians, have shown more pronounced cases of obstructive sleep apnea (OSA). However, the extent of these racial differences is less evident in other populations. Lumeng et al. [7] also noted that SDB tends to be more prevalent among male children and those with a higher body weight. While SDB is commonly observed in children aged 2–5 years, it can manifest across all age groups. Additionally, a genetic predisposition is associated with OSA, and it is probable that both genetic and environmental factors contribute to its occurrence [7].

3. Predisposing factors for pediatric OSA

3.1 Anatomical structure

The patency of the airway hinges on a delicate equilibrium involving various factors. These encompass the inward collapsing forces, influenced by intraluminal negative pressure and airway structure, and the outward dilating forces generated by the pharyngeal muscles and alterations in lung volume. Numerous elements come into play here, including anatomical features, neuromotor control, and the presence of inflammation [8]. For individuals with obstructive sleep apnea (OSA), investigations have revealed heightened susceptibility to upper airway collapse during wakefulness. This susceptibility may, in part, be attributable to a potential diminutive pharyngeal airway in these patients. Utilizing awake patients in computerized tomography (CT) scans, Haponik et al. [9] observed reductions in cross-sectional areas within the nasopharynx, oropharynx, and/or hypopharynx of OSA patients. Schwab et al. [10] likewise employed CT imaging, disclosing that an enlarged tongue and lateral pharyngeal wall size were independent risk factors for OSA. Furthermore, the physical dimensions of the craniofacial and dentofacial skeletal structures, coupled with the amount of soft tissue within and surrounding the airway, significantly influence airway size. It is well-established that adenotonsillar tissue attains its greatest relative size during the initial years of life and gradually regresses with adolescence and adulthood (see Figures 1 and 2). Employing magnetic resonance imaging (MRI), Ni et al. [11] ascertained that in children experiencing OSA and primary snoring, the upper airway is constricted by both adenoids and tonsils. Additionally, children with OSA exhibited larger soft palates, further contributing to this constriction.

Figure 1.

Obstructive sleep apnea occurs when muscles at the back of the throat relax and obstruct air-flow.

Figure 2.

Hypertrophied adenoid tissues.

3.2 Neuromuscular

Many children experiencing obstructive sleep apnea (OSA) demonstrate the capacity to intermittently establish a consistent breathing rhythm during sleep. This observation suggests the potential for neuromuscular compensation beneath the arousal threshold, highlighting that factors beyond anatomical attributes influence airway patency [12]. In instances involving children with neurological conditions, such as cerebral palsy, the manifestation of sleep-disordered breathing (SDB) and OSA becomes more apparent. These neurological disorders contribute to the development of OSA by impairing upper airway motor control, resulting in pharyngeal hypotonia, diminished ventilator responses, and reduced respiratory muscle strength. Elsayed et al. [13] documented a 50% prevalence of SDB among a cohort of 48 school-aged children with cerebral palsy. In a separate retrospective investigation utilizing overnight polysomnography on children afflicted with cerebral palsy, Kotagal et al. [14] identified that five out of nine subjects were diagnosed with OSA. These findings underscore the complex interplay between neurological factors and airway patency in this context.

3.3 Pro-inflammatory factors

Obstructive sleep apnea (OSA) also appears to give rise to a subtle form of systemic and local inflammation. This phenomenon is believed to stem from intermittent episodes of hypoxia and disruptions in sleep, leading to the generation of free radicals and systemic oxidative stress. Investigations have unveiled inflammatory alterations within upper airway samples from children grappling with OSA. Furthermore, elevated levels of cysteinyl leukotrienes (CYS LT), recognized as significant inflammatory mediators and potent activators of neutrophils, have been identified [15, 16]. Interestingly, the expression of receptors associated with these compounds has been observed to be heightened in children afflicted with OSA in contrast to those with recurrent infectious tonsillitis. This suggests the involvement of an inflammatory process characterized by the expression and regulation of leukotrienes in children with OSA.

Systemic inflammation, as discerned through C-reactive protein (CRP) levels, has exhibited an upward trajectory in individuals with OSA. Remarkably, following adenotonsillectomy, there is often a discernible decline in systemic inflammation, typically observed within 3 months [17]. The rise in systemic inflammation has been hypothesized to be a consequence of episodic episodes of hypoxia and sleep arousal. The ongoing quest is to unravel whether local and systemic inflammation serves as a component or a causative factor in OSA. The prevailing body of evidence leans toward adenotonsillectomy as an intervention that mitigates inflammation in OSA, whether at the local or systemic level [15]. Nonetheless, there remains a dearth of data affirming the presence of pre-existing inflammation in children newly diagnosed with OSA.

Cytokines serve dual roles, influencing both sleep regulation and contributing to the development of obstructive sleep apnea (OSA). These small proteins are instrumental in orchestrating the body’s immune response. Interestingly, the levels of pro-inflammatory cytokines tend to peak during the nighttime hours. In the face of illness, heightened pro-inflammatory cytokine levels align with increased feelings of fatigue, amplifying a patient’s sense of weariness. This instinctual response to the onset of illness promotes extended periods of sleep, aiding in the recuperation process. Cytokines also exert an influence on sleep architecture by intensifying and fragmenting deep non-rapid eye movement (NREM) sleep while concurrently diminishing rapid eye movement (REM) sleep. This phenomenon can elucidate why individuals often experience restless sleep during bouts of illness. Of particular note are two cytokines, namely interleukin-1 beta (IL1) and tumor necrosis factor-alpha (TNF), which have been extensively studied for their roles in sleep regulation. Evidence gleaned from animal studies has demonstrated that the systemic or central administration of either IL1 or TNF enhances the duration of NREM sleep and augments electroencephalogram (EEG) delta wave power during NREM sleep [18].

3.4 Obesity

Obesity stands out as a recognized risk factor for obstructive sleep apnea (OSA) in the adult population. Insights drawn from various epidemiological investigations indicate that the prevalence of OSA among obese children falls within the range of 46–55% [19]. The mechanisms underpinning how obesity contributes to the development of OSA are multifaceted, encompassing both mechanical and functional aspects. Through a comprehensive volumetric analysis of the upper airway in obese children afflicted with OSA, Arens et al. [20] documented notable distinctions. They observed that OSA-affected children exhibited enlarged adenoids, tonsils, and parapharyngeal fat pads in comparison to their matched counterparts. Additionally, it is worth noting that obese children may accrue an excess accumulation of adipose tissue within the muscles and the surrounding airway structures, potentially influencing the configuration of the chest wall (see Figure 3).

Figure 3.

Airways at the level of oropharynx constricted (left) due to fats infiltration vs normal (right).

4. Diagnosis of sleep disturbances

4.1 Sleep-disordered breathing screening questionnaires

Screening questionnaires serve as essential tools in identifying individuals at elevated risk of developing obstructive sleep apnea (OSA). Phase I screening instruments typically encompass specific initial inquiries conducted during routine healthcare maintenance visits. These instruments aim to aid healthcare providers, including pediatricians, in recognizing symptoms associated with snoring and other sleep-related issues in children. Notable examples of these screening tools encompass BEARS, the Epworth Sleepiness Scale [21], the Ten-Item Sleep Screener (TISS) [22], and the Pediatric Sleepiness Scale [23].

4.2 Polysomnography

For the diagnosis of obstructive sleep apnea (OSA), the gold standard remains the overnight, attended, in-laboratory polysomnogram. This diagnostic test uniquely possesses the capability to quantitatively assess both the respiratory and sleep irregularities associated with OSA in children [22]. Referred to as Type I sleep diagnostic testing, this non-invasive procedure takes place within a specialized sleep laboratory and is overseen by skilled technologists who remain present throughout the study’s duration [24]. It involves the measurement and analysis of intricate polygraphic signals collected from three distinct channels, capturing various physiological functions [4].

5. Clinical symptoms and complications of OSA

5.1 Behavioral and neurocognitive deficits and or poor schooling and academic performance

Those children with OSA show reduced attention capability, hyperactivity, increased aggression, irritability, emotional and peer problems and somatic complains [13, 25]. Neurocognitive deficits include a reduction in memory and intelligence [26], have shown that 13-year-old children with low academic performance are more likely to snore during early childhood compared with children with high academic performance. However, whether this restricts the affected children’s future academic and occupational success is largely unknown.

5.2 Cardiovascular complications

The cardiovascular complications of OSA are of immediate importance because earlier diagnosis and treatment can reverse these processes and prevent their consequences in adult life [1]. Recurrent episodes of upper airway obstruction, which are characteristic of OSA result in intermittent hypoxia, intrathoracic pressure swings, and sleep fragmentation. This results in autonomic system activation supported by the following findings: increased urinary catecholamines, decreased pulse transit time, and alterations in blood pressure regulation in OSA. Right ventricular dysfunction has also been demonstrated [27]. Cardiac benefits of treatment for OSA have been shown. Plasma levels of B-type natriuretic peptide, a marker of ventricular strain, have been found to be elevated in children with OSA and to decrease after Adenotonsillectomy. Similarly, there is evidence of echocardiographic improvement of elevated pulmonary pressure also after Adenotonsillectomy.

5.3 Sleep habits related to pediatric OSA

5.3.1 Nocturnal bruxism

Sleep bruxism is believed to be linked with the arousals influenced by fluctuations in the sympathetic and parasympathetic nervous systems during sleep. Activation of the sympathetic nervous system occurs as a result of arousal and hypoxia [28]. It is plausible that respiratory disturbances, which lead to sleep disruptions and arousal, prompt the muscles in the masticatory system to restore normal breathing. Sleep bruxism may serve to alleviate upper airway obstruction. Therefore, if bruxing and clenching are regarded as part of the arousal process, it’s possible that arousal stemming from apnea could trigger bruxism. Several studies have established a positive correlation between the frequency of apneic episodes and sleep bruxism in obstructive sleep apnea (OSA) [29].

5.3.2 Nocturnal enuresis

Nocturnal enuresis is characterized by the involuntary release of urine during sleep in children aged 5 years or older, with a prevalence of approximately 5–10% among young schoolchildren. Monosymptomatic primary nocturnal enuresis (NE) is considered one of the comorbidities linked to obstructive sleep apnea (OSA). The treatment of NE, whether through adenotonsillectomy or other therapeutic measures such as nasal corticosteroids or rapid maxillary expansion, has been associated with the resolution or reduced frequency of enuresis episodes [30].

5.4 Quality of life and healthcare resource utilization

Oral health is an integral component of systemic health. The links between the two make this topic an imperative public health issue. Poor oral health may affect quality of life (QoL) by interfering with a person’s ability to eat, sleep, and function. It can also contribute to systemic illness, and may further exacerbate challenging and costly medical care. The total number of admissions in children with OSA is 40% higher as compared to matched controls [31]. The validated Child Oral Health Impact Profile (COHIP) is used to assess children’s health-related quality of life (OHRQoL) based on the answers given by parents or guardians and by the children themselves. The COHIP measures how oral health affects daily activities such as speaking, eating, smiling, learning, and emotional/social well-being. It consists of 35 items forming five conceptually distinct domains: oral health, functional well-being, social/emotional well-being, school environment, and self-image. A subscore for each of the five COHIP domains and an overall total COHIP score are calculated. Higher scores reflect worsened OHRQoL. Patient demographics and lifestyle factors such as age, sex, parental education, and smoking are also gathered as part of the COHIP questionnaire. OHRQoL scores significantly improve following treatment [32]. In summary, OSA is associated with serious and measurable end-organ dysfunction. Treatments for OSA are available and the benefits of treatment have been demonstrated which argue for timely diagnosis and treatment of OSA to avoid long-term negative consequences.

6. Treatment of pediatric OSA

6.1 Weight loss

it’s evident that encouraging activities to achieve weight loss and making lifestyle adjustments holds promise for enhancing glucose regulation. Furthermore, there’s supportive evidence highlighting the role of weight loss in managing obstructive sleep apnea (OSA) [33]. In the Wisconsin Sleep Cohort Study, researchers conducted prospective observations to examine changes in the Apnea-Hypopnea Index (AHI) and the onset of sleep-disordered breathing (SDB) in relation to weight fluctuations. The results indicated that maintaining weight control was linked to reductions in AHI and a decreased likelihood of developing OSA [34]. These findings align with evidence derived from randomized controlled trials. For instance, in the Sleep AHEAD study, individuals who were both obese and had type 2 diabetes and OSA were randomly assigned to either an intensive lifestyle intervention program, involving behavioral weight loss and physical activity, or a diabetes support and education regimen. The study demonstrated that the intensive lifestyle intervention led to greater weight loss and reduced AHI over 4 years compared to diabetes support and education alone [35]. Other randomized trials exploring diverse lifestyle modifications, including very low-calorie diets combined with active lifestyle counseling, intensive exercise training, cognitive-behavioral weight loss, and very low-calorie diets, also revealed improvements in OSA severity with these interventions [36]. Importantly, the potential effects of these lifestyle measures on OSA may endure over time [37].

6.2 Adenotonsillectomy

Tonsillectomy and adenoidectomy represent the established primary treatment approach for children diagnosed with obstructive sleep apnea (OSA), and research indicates that the combined removal of both tonsils and adenoids yields superior outcomes compared to either procedure performed in isolation. The underlying rationale centers on the observation that adenoid and tonsillar hypertrophy is most prevalent between the ages of 2 to 6, during which the pharyngeal lymphoid tissue surpasses the capacity of the surrounding airway structures, precipitating pharyngeal obstruction during sleep [38].

Remarkably, the combined tonsillectomy and adenoidectomy procedure has been shown to markedly ameliorate obstructive symptoms in approximately 80% of cases. According to parental-reported questionnaires, this intervention boasts an efficacy rate of approximately 91% in addressing snoring concerns [39]. Furthermore, assessments based on the OSA-18 questionnaire, as well as subjective and objective evaluations of children’s behavior, all reveal significant enhancements post-surgery [23]. Nonetheless, it’s worth noting that Guilleminault et al. [40] reported that 13% of children who initially responded positively to tonsillectomy and adenoidectomy experienced a recurrence of symptoms upon reaching adolescence. Therefore, ongoing monitoring remains imperative for these patients, even in cases where the initial response to the procedure was favorable.

6.3 Orthodontic treatment of OSA

Persistent OSA post-AT has also led to the consideration of orthodontic modalities to treat OSA. There are several craniofacial abnormalities where imbalanced development may contribute to OSA such as posterior crossbite, Class II skeletal and dental patterns, and anterior open bite. Aside from esthetic and occlusion benefits, orthodontic treatment can help guide facial growth in order to correct facial imbalances, improve swallowing, reposition tongue posture, and re-establish nasal breathing [41]. Early detection and treatment of children with OSA and facial imbalances may prevent the sequelae of this disease. Early orthodontic treatment could prevent a need for AT and provide another treatment option for children with OSA who are not adherent to other therapeutic modalities.

6.3.1 Rapid maxillary expansion

Rapid Maxillary Expansion (RME) is a common orthodontic procedure used to correct maxillary arch constriction by opening the mid-palatal suture. It is a common treatment modality to correct posterior crossbites in the primary, mixed, or permanent dentition. The precise role of maxillary constriction in the pathophysiology of OSA is unclear. However, it is known that a significant number of children with OSA have nasal obstruction (nasal septal deviation with or without turbinate hypertrophy) associated with a narrow maxilla [42]. Maxillary constriction is thought to increase nasal resistance and alter tongue position, leading to the narrowing of the retroglossal airway and subsequently the development of OSA [43].

There is no evidence to support that RME enlarges oropharyngeal airway volume. [44], retrospectively studied 24 adolescent patients (mean ± SD age 12.8 + 1.88 years) with maxillary constriction using hyrax palatal expanders and compared that to 24 control patients (mean ± SD age 12.8 + 1.85) undergoing routine orthodontic treatment without palatal expansion. They used cone-beam computed tomography (CBCT) to assess changes in the volume, length, and minimum cross-sectional area of the oropharynx. They found no statistically significant differences between the groups. On the other hand, RME has been shown to increase nasal width and nasal cavity dimensions. [45], investigated the effect of RME on 31 children (19 boys, 12 girls) with maxillary constriction, without adenoid hypertrophy, with OSA demonstrated by PSG. RME was performed for 10–20 days with 6–12 months of retention. The mean AHI fell from 12.2 events per hour to less than one event per hour, demonstrating a resolution of the SDB.

6.3.2 Functional appliance therapy (twin block appliance)

Functional appliances encompass a category of intraoral devices, available in removable or fixed forms, designed to influence muscle forces affecting the teeth and craniofacial skeleton. Their mode of action relies on the alteration of neuromuscular dynamics to stimulate bone growth and facilitate occlusal development. In the context of children with obstructive sleep apnea (OSA), these functional appliances have found utility due to their capacity to reposition the mandible forward, potentially enlarging the upper airway and augmenting upper airspaces, thereby enhancing respiratory function [46].

One such functional appliance is the twin block, introduced by William J. Clark in 1977. Its primary objective is to enhance the functional interplay among dentofacial structures by mitigating unfavorable developmental factors and optimizing the muscular environment surrounding occlusion development. Through adjustments to tooth and supporting tissue positions, the twin block establishes a novel behavioral pattern conducive to a new equilibrium position. This appliance comprises dual plates featuring occlusal bite blocks and inclined planes that guide the mandible to descend and move forward. In its initial iteration in 1977, the twin block featured a 90-degree interlocking angle between the inclined planes. However, by 1982, it was recommended to reduce this angle to 45 degrees, promoting an equal combination of downward and forward force components upon full closure. Subsequent clinical experience led to further refinement, with a recommended interlocking angle of 70 degrees. This adjustment aimed to produce a predominantly horizontal force component and stimulate more pronounced forward mandibular growth (see Figure 4). The twin block regimen involves continuous wear, spanning 24 h each day, including mealtimes, to harness all functional forces applied to the dentition, including those arising from chewing (masticatory forces).

Figure 4.

Twin block appliance.

7. Clinical efficacy of twin block on pediatric OSA

7.1 Effects of twin-block appliance on upper airway parameters using CBCT study

Several reports have advocated the twin block as an efficient oral appliance for the treatment of children with class II skeletal malocclusion with retrognathic mandible with the advantage of being non-invasive and well-tolerated by children [47, 48]. Clinically, twin block appliance therapy could significantly reduce apnea-hypopnea index (AHI) and snoring time, increase the overall oxygen saturation, and improve symptoms related to OSA such as quality of life, behavior, and schooling performance [49, 50]. Anatomically, results have shown an improvement in upper airways dimensions following functional appliance therapy [51, 52].

In 2022, Dr. Zreaqat and his colleagues conducted a prospective study about the effect of twin block appliances on the upper airways of OSA children with class II malocclusion using CBCT scans [53]. They found that correction of class II mandibular retrognathic skeletal malocclusion with twin-block appliance resulted in a significant increase of upper airway volume, minimum cross-sectional area (CSA_min), anterio-posterior and lateral distances of CSA_min at the level of oropharynx, CSA_min at the level of the hypopharynx, upper airway length, and significant decrease in AHI but it has no effect on nasopharynx parameters.

7.2 Effects of twin-block appliance on urinary LTE4 and serum CRP levels in OSA children with class II malocclusion and mandibular retrognathia

Dr. Zreaqat and his colleagues evaluated the effect of twin block appliance therapy on urine leukotriene E4 (uLTE4) and serum C-reactive protein (CRP) levels in OSA children with class II malocclusion and retrognathic mandible [53]. At the end of treatment, a significant improvement in respiratory parameters was observed in the treatment group. AHI, the most important PSG parameter, decreased by 3.52 events/hour (50.65% decrease). A threshold of ≥50% in reduction of the AHI was considered the criterion for response to treatment [54]. This study’s results agreed well with this threshold. Reduction in the AHI after OSA treatment with oral appliances is a common finding in most sleep publications. However, the degree of AHI change after treatment varies considerably; [48], reported an average AHI decrease of 75.9% after twin-block appliance therapy for pediatric OSA. Others reported lower values of AHI reduction: 63.4% by Villa et al., [55], and 28.6% by [49]. Patient compliance might partially explain these conflicting findings, as patients wearing the twin-block appliance might have a more stable and favorable muscle function against upper airway collapsibility than non-compliant patients. In addition, inconsistencies in patient selection criteria and different underlying OSA etiologies might have a role. Twin-block appliance therapy is advantageous in treating pediatric OSA and reducing the overall AHI, although it does not return to normal pediatric reference values. However, it should be noted that some AHI changes may have been attributed to the growth of the upper airway or regression of lymphoid tissues.

7.3 Effects of twin-block appliance on quality of life in OSA children with Class II malocclusion and mandibular retrognathia

Dr. Maen Zreaqat and his colleagues conducted a prospective trial to test the effect of twin block appliances on the quality of life in children with OSA [53]. Results have shown that twin-block appliance therapy resulted in a significant improvement in four out of five domains of the OSA-18 questionnaire including sleep disturbances, emotional distress, daytime problems, and caretaker concerns. The change in total scores of the OSA-18 questionnaire was 28.48 reflecting mild to moderate impact on quality of life. This was the only study that tested the effect of an orthodontic oral appliance on growing children near adolescence. [56], proposed a modified monobloc orthodontic appliance in 4–8 years old OSA children which showed to improve subjective sleep quality and daytime performance among children. In pediatric OSA, most trials evaluated the impact of surgery (adenotonsillectomy) on the quality of life. Several published studies supported the benefits of an adenotonsillectomy on quality of life in children with OSA [57, 58, 59]. These studies showed that surgery offers patients important cognitive and intellectual benefits despite the recurrence of sleep symptoms after surgical intervention in some cases [60, 61] found that adenotonsillectomy had a positive impact on quality of life where the improvement remains for at least 22 months after the surgery.

In adults, quality of life was tested with continuous positive airway pressure (CPAP) and mandibular advancement device (MAD) therapy. Both modalities have a significant influence on quality of life and proven to enhance functional and behavioral outcomes in adults with mild to moderate OSA. Although MAD therapy is less effective than CPAP in treatment outcomes, it has a higher reported compliance and adherence to therapy than that observed in CPAP with a better tolerance rate [62]. Barnes et al. [63], found that treatment with mandibular advancement splint MAS improved quality of life as measured by the Functional Outcomes of Sleep Questionnaire mean score and social outcome domain and by the sf36 overall health score. Gagnadoux et al. [64], evaluated the effect of mandibular advancement devices on quality of life using Nottingham Health Profile (NHP) and found significant improvement in four out of six domains including physical mobility, pain, emotional reaction, and sleep. On the other hand, [65], found no significant effects of oral appliance therapy on quality of life but their results might be biased by the short-term of course treatment (4 months only). In fact, most MAS is used in the treatment of adult OSA but their application in growing children or adolescents is limited due to the dramatic skeletal and dentoalveolar changes and over-bite alterations they result in which preclude their widespread use. Instead, myofunctional orthodontic appliances are implemented where occlusal changes are favorable particularly in children with class II malocclusion and mandibular retrognathia. Continuous positive airway pressure (CPAP) was first described by Colin Sullivan in 1981 as a potential treatment of OSA and has become, since then, the first-line therapy for moderate to severe OSA in adults. CPAP demonstrated superior efficacy over mandibular advancement devices in improving the AHI scores and daytime sleepiness but it has lower adherence to therapy which may result in comparable effectiveness for both treatments. Phillips et al. [62], found that both CPAP and MAD therapies improved neurobehavioral domains and quality of life scores in a similar way.

8. Conclusion

Treatment of pediatric OSA with twin block appliance did not affect urinary LTE4 and serum CRP levels despite the significant improvement in dentoalveolar features and respiratory sleep parameters. In addition, myofunctional twin block therapy has a positive impact on quality of life in growing children with OSA and patients show significant improvements measured with PSG and parent-reported symptoms. However, the long-term effects of twin block therapy on pediatric OSA remain unclear and need to be addressed in future studies.