Functional Appliances in the Treatment of Sleep Apnea in Children: A Systematic Review

AHI: Apnea/Hypopnea Index; OSA: Obstructive Sleep Apnea; REM: Rapid Eye Movement; SDB: Sleep Disordered Breathing; UA: Upper Airways; PS: Primary Snoring; OB: Oral Breathing; PSG: Polysomnography Exam; CPAP or BPAP: Air Pressure Devices; FA: Functional Appliances

Obstructive Sleep Apnea (OSA) is a breathing disorder sleep characterized by partial or complete obstruction of the Upper Airways (UA) interfering with the normal sleep pattern. The prevalence of this disease in children is 0.2 to 3% [1-4]. Children with OSA usually present insidious signs and symptoms such as Primary Snoring (PS), Oral Breathing (OB), behavioural disorders, hyperactivity daytime, which cannot be recognized as part of that disease [5-11].

The Polysomnography Exam (PSG) is considered the gold standard for diagnosis, expressed by the apnea and hypopnea index (AIH), classified according to the number of occurrences per hour of sleep: the diagnosis is confirmed when the AHI is higher than [1,12,13]. The criteria diagnostic for children are different from adults and have not been completely established yet [4]. Many studies suggest more diagnostic tools and options should be considered, such as parents reports, clinical examination, questionnaires addressing behavioral and cognitive information and 3D imaging studies [14-23]. The multi displinary and multi professional nature of the disease, recommending an interactive diagnostic approach [24-28]. Adenotonsillar hypertrophy is known to be the main risk factor for the disease [1-11] followed by obesity, neuromuscular disorders and craniofacial anomalies [29-34]. The gold standard treatment for children is removal of the oropharyngeal lymphoid tissue [9,11,30-34]. Treatment during childhood is believed to be crucial; the delay in its recognition may play a negative influence on the quality in their adult life [35-38].

The most common non-surgical types of treatment include devices of air pressure (CPAP or BPAP), however, they are expensive and little accepted by children [39,40]. Recurrence of the clinical condition can happen after adenotonsillectomy, and it is believed to be due to concomitant craniofacial problems, among others [41-43]. These alterations can be easily recognized and treated by the orthodontist [23-26]. The persistence of OB and PS during the growing and developmental period may lead or exacerbate dental skeletal changes [39,42,43]. The incurred changes coupled with genetic predisposition make the OSA even more severe, allowing the development of a vicious circle. Orthodontic appliances can be used before or after surgery as preventive or curative [5,6,34,39,42-49]. The FA is widely used in children to promote mandibular growth and to improve craniofacial changes [50-56]. The mandibular advancement devices protrude the mandible and the tongue, increasing the passage diameter of the UA, improving the tonicity of the muscles in the region, particularly the genioglossus muscle, and consequently preventing the collapse of the soft tissue [57-63].

FA offer no risks, they are well tolerated by the patients, they minimize the overall costs of the treatment and are an alternative for the children treatment with OSA who persist with the disease after surgery [42,44]. The best results are obtained when the child enters in the pubertal growth spurt [51-57]. The restriction of this treatment is the lack of children´s cooperation by not using the device properly. Good results depend on the appropriate device use, at least for 12 months, all day long [59-65]. The objective of this research was to demonstrate through a systematic review, the effectiveness of a FA in the treatment of OSA in children.

The search was in the databases included "pubmed, scholar, Medline, scielo" with the filters, "human, children, in all languages, with the key words "obstructive sleep apnea and children and orthodontic appliance" between the years 1988-2015. Initially were obtained 49 studies and 14 studies were excluded from the first selection by checking their overall goals as Osa and enuresis, OSA and syndromes. This pre-selection was made by three researchers individually. The selected 35 studies were requested by subjects in a comprehensive manner, including etiology of the disease, related to other sicknesses such as OB, PS, size of UA, diagnostic and treatment. The results of research we could see in Table 1.

Table 1: First selection.

A second selection was made, only including studies which are related to OSA with FA and Orthodontics. Articles dealing with OSA and other diseases as OSA and weight, OSA and rapid maxillary expansion, Osa and surgical treatments, OSA and diagnosis, were excluded, so were obtained 13 specific studies on this subject but, only 8 of them were eligible by level of evidence [66]. Some review and clinical studies that dealt with OSA and other variants which were excluded from the systematic review but some helped to explain the matter. These articles were citaded in the introduction of the study. The search methodology, is illustrated in the Figure 1.

Figure 1: Search in the database and selection studies.

Eight studies addressed to FA impact in the treatment of OSA, but the results, could not answer yet the question whether the use of the device type can improve OSA. These studies were listed below by chronological order and methodologically summarized in Table 2.

Selected Studies- Chronological order

Villa et al. [47], evaluated the clinical use and tolerance of FA for OSA treatment in 32 children at an average age of 7.1 ± 2.6 years, 20 boys and 12 girls who had OSA symptoms an AHI>1 event per hour and malocclusion. Randomly were selected 19 patients (SG) with AHI=6, which used the FA and the remaining patients formed the CG. After the treatment, the polysomnography exam showed the SG achieved a significant decrease in the AHI compared to the same index at the treatment beginning, and the CG showed no change. Clinical symptoms examination before and after the appliance use showed that 7 of the 14 subjects, had reduced 2 points in the score of respiratory symptoms, and 7 had solved the main complaints of respiratory symptoms compared to the CG which continued with baseline symptoms. Therefore, they concluded the treatment of OSA with FA is effective and well tolerated.

Cozza et al. [51], in a comparative clinical study evaluated 20 children (10 boys and 10 girls) aged between 4 and 8 years with OSA and 20 control children (10 boys and 10 girls) aged 5 and 7 years without OSA to determine the differences between groups and check the FA effects with PSG and cephalometric. Anatomic differences statistically significant were detected among CG and SG. Polysomnography was repeated after six months in the group with OSA, having noticed that the use of FA, promoted a statistically significant reduction in AHI (P=0.0003). The use of the device reduced daytime sleepiness and subjectively improved sleep quality. Parents and patients reported good cooperation in dealing with intra-oral appliance.

Table 2: Evidence vased included studies (OSA e FA).

Carvalho et al. [48], through a systematic review investigated the effectiveness of treatment of OSA in children with FA. Randomized studies were selected and do not have randomized trials comparing all types of orthopedic devices with placebos or not, in children at 15 years old. They demonstrated through the results the improvement in the AHI, in the dento skeletal relations, sleep parameters, cognitive and speech, behavioral problems, quality of life, side effects, and economic and social aspects. Therefore, the authors concluded that there is no evidence enough to confirm the effectiveness of the devices for sleep disorders. The devices improve the craniofacial characteristics of children who have risk factors for OSA but there is no way to prove these.

Godt et al. [44] investigated the width of the upper airway in different facial patterns and changes during the various treatments including FA for Class II. They used cephalograms before and after the three treatment modalities (headgear, FA and bite jumping). Little increase in UA was observed around the vertical level during the treatment, and they concluded that no significant changes occurred in those segments during treatment. In addition, with headgear, the UA size decreased.

Van Holsbeke et al. [64] conducted a study with 143 patients with OSA, who used FA. CT scans were performed with minimal radiation dose before and after placement of the apparatus and the changes were verified using a bite simulator able to show resistance change in the UA. They demonstrated that ideal patients for the success were women with small UA and high early strength.

Kizinger et al. [42] in a retrospective cephalometric study found that the two forms of fixed functional appliances to correct Class II (Herbst and FA) influenced the morphology of the UA. The sample consisted of 43 patients, 18 patients used the FA and 25 used the conventional Herbst (fix FA). Measures of cephalometric analyzes were verified and compared in two times. Both devices had similar effects. They concluded that treatment with FA cannot prevent the risk of OSA although studies cephalogram are not able to measure the depth of the upper airways.

Iwasaki et al. [60], in a clinical study, observed a sample of 24 patients of Angle class II, who opted for Edwise fixed therapy compared to a group that used Herbst Fixed FA. The three dimensions of the oropharynx through CT scans, were verified in 11 children at mean age of 11.6 years old, who had already taken 3D Cone Beam before and after Herbst´s therapy. The CG was obtained in a sample of 20 patients Angle Class I, who opted for treatment with fixed orthodontic and had the same tests. The group opted for the Herbst´s appliance (SG) found a significant increase in the volume of the upper UA compared to CG.

Huynh, et al. [65] conducted a systematic review and meta-analysis to check the effectiveness of orthodontic appliances in the treatment of OSA in children and adolescents. Eligible studies were investigated in Pubmed, Medline, Embase, and Internet published until April 2014 were identified, in a total of 58 studies. Only eight studies were included in the review. Among these, six were included in the meta-analysis. The search yielded only a small number of studies. Consequently, any findings of diagnostic parameters grouped and their interpretation should be treated carefully (Table 2). The researches in which patients used FA, presented clinical positive results but not statistical results. The results showed decreasing or disappearance of the OSA symptoms and also an improvement of the clinical outcome regarding craniofacial deformities caused by the sleep respiratory disorder [6,48,49,62,63,65].

OSA has a negative impact on child growth, affecting their quality of life. If the condition persists, it may affects the quality of life in their adulthood [1,15,35-38]. Tonsil hypertrophy is considered the leading cause of OSA [1-11,13,23,27,30]and tonsillar removal is the optional treatment [3,5,6,9,10,27-29,31-34]. Common diseases such as oral breathing and primary snoring are related to OSA and if there is an association with craniofacial abnormalities, this may lead to the recurrence of the OSA after adenotonsillectomy [23,24,32-34,39,44,45,63]. The literature showed the most frequent complaints of patients with OSA were PS and troubled sleep. Allergic rhinitis RA was the most frequent comorbidity accompanying OSA, followed by hypertrophy of the tonsils [1,2,4,8,11,20,26,29]. The most severe apnea indexes were found in younger children, and African descendants had a higher prevalence of the disease [9]. One study [33] reported that the tonsillectomy surgery was effective for the treatment of OSA in a group of children aged between 3 to 6 years old, who returned to a normal growth pattern. On the other hand, other studies reported that adolescents aged between 11 and 14 years old, continued with OB after the removal of the tonsils, presented the worst AHI and reduction of UA lumen [5,6,9,10,29,34]. The causal effect between tonsil hypertrophy and OSA has not been established yet [40,45].

Treatments for persistent apnea are not completely known yet. Treatment approaches must be better evaluated [10,11]. Anti-inflammatory therapies, masks for ventilation and oral appliances are offered to the treatment of recurrent OSA but the disease remains a challenge due to its multifactorial nature [1-3,11,39,48,63,65]. Some authors consider as the best form of clinical treatment of OSA the use of CPAP or BPAP but such treatment does not get a good patients cooperation and the discontinuance is large [26,27,39,40,41].

Two reports of clinical case studies demonstrated OSA improvement with the use of FA [49,50]. In both studies, high AHI were reported, but the patients did not have tonsillar hypertrophy and craniofacial deformities were treated with FA. The treatment improved the OSA and normalized the craniofacial deformities. Reports of clinical cases do not represent a high level of evidence and do not show statistical significance, but can be considered a warning about the clinical need of new approaches. Isolated cases, out of average, should be considered for further investigation. Early intervention of the orthodontist with FA in patients with disorders of the craniofacial structures in cooperation with other specialists should be considered [26,27]. The FA promotes an increase in mandibular growth and permanently changes in the craniofacial structure, facilitating the breathing mode and preventing obstructions of the UA. [42]Orthodontists are professionals trained to recognize and treat OSA with FA in patients with craniofacial anomalies [5,6,15,25,28] promoting a harmonious facial growth and avoid aggressive surgery in adulthood and cardiovascular comorbidities resulting from sleep disorders [16,41,42,62].

The FA are simple, silent, well tolerated and effective, but some challenges still remain, as the need for monthly monitoring by the professional for more than twelve months, which may discourage the patient[43-66]. Studies have shown that the use of FA can eliminate or reduce the symptoms of the OSA, promoting a better long-term quality of life [35-38]. The PSG tests have been considered the gold standard in OSA diagnosis. Perhaps due to the difficulty in performing these exams, by of the lack of specialized centers and the high cost, making most of the clinical researches outcomes were not investigated with this exam. Some of the studies were not able to include enough patients for an statistical result maybe because of the difficulty of suitable sample allocation in the inclusion criteria [5,6,14,42-50,52,59-65].

Some researchers used 2D image parameters to check UA [42,44,51] and did not obtain reliable results. Few studies included patients monitored with polysomnography [42,44,47] and were not able to report improvement of OSA based on AHI parameters.

The difficulty in assessing the results of the studies was due to the differences in the used methodologies. The different investigated devices and patient maturity were not homogeneous, creating difficulties in the methodological comparisons. Many of them, showed positive results in the improve of OSA with FA but the parameters used to measure the effectiveness were not similar and acceptable [42,44,47,51,60,64]. A recent study of systematic review [65] evaluated several types of orthodontic therapy, and did not answer the purpose of our research. Due to the difficulty of conducting well-designed studies with samples and suitable tests for good results, there is no strong evidence that FA is indeed effective in the treatment of obstructive sleep apnea in children.

This systematic literature review showed that orthopedic devices seem to be a good treatment option for children with OSA. Although the level of evidence of the effectiveness of these devices is weak to moderate, as there are no randomized controlled clinical studies that support this hypothesis (H0), but either do not reject it. There is still need for more well designed controlled research, with large enough case series in order to accurately obtain the answer.