Abstract
Background: Sleep-Disordered Breathing (SDB) varies from habitual snoring to partial or complete obstruction of the upper airway, and can be found in up to 10% of children. SDB can significantly affect children’s wellbeing, as it can cause growth disorders, educational and behavioural problems, and even life-threatening conditions, such as cardiorespiratory failure. Adenotonsillectomy represents the primary treatment for paediatric SDB where adeno-tonsillar hypertrophy is indicated. For those with craniofacial anomalies, for whom adenotonsillectomy or other treatment modalities have failed, or surgery is contra-indicated, mandibular advancement splints (MAS) may represent a viable treatment option. Whilst the efficacy of these appliances has been consistently demonstrated in adults, there is little information about their effectiveness in children.
Study objective: The aims of this research are first, to define the most accepted appliance from different designs of MAS to be used in the main study and second, to determine the efficacy of mandibular advancement appliances (MAS) for the management of Sleep-Disordered Breathing (SDB) and related health conditions in children.
Methods: The first part of this research was a pilot study designed as a randomized controlled study with crossover application of four different MAS designs. Questionnaires filled out by the patient and parent were used to gauge effectiveness of the different MAS designs regarding: the effects on speech, the initial acceptance, and the acceptance after wearing the appliance for a full night. A clinical examination then followed to test the appliance retention. One volunteer (11 year old male with class II dental and skeletal jaw relationships) participated in this pilot study and he was suitable for functional appliance treatment. Appliances tested were: 1) traditional Twin-Block with vertical elastics added to ensure the anteroposterior and vertical predetermined position of the mandible when wearing the appliance during sleep; 2) Twin-Block with a metallic fastener in the anterior area to test the function of mandibular advancement; 3) Clear elastic Twin-block which has the same traditional Twin-Block design with vertical elastics but uses vacuum formed retainers instead of the acrylic material; 4) a sham Twin-Block with upper and lower vacuum formed retainers without any mandibular repositioning. This pilot study showed that traditional Twin-Block was the best design to be used in the main study as it was highly accepted by the patient and showed the highest levels of retention in comparison to the other designs.
The main study was designed as a single-blind crossover randomised controlled trial with administration of both an ‘Active MAS’ (Twin-block) and a ‘Sham MAS’ (two Hawley retainers). Eligible participants were children aged 8 to 12 years, whose parents reported them snoring ≥ 3 nights per week. Exclusion criteria included class III incisor and/or skeletal relationship, confirmed by lateral cephalometric radiograph. 18 children participated in the study. Each child was randomly assigned to a treatment sequence, starting with either the Active or the Sham MAS. Participants wore the appliances for three weeks, separated by a two-week washout period. For each participant, home-based polysomnographic (PSG) data was collected four times, once before and once after each treatment period. The Apnoea Hypopnoea Index (AHI) represented the main outcome variable. Secondary outcomes, assessed at the same time with PSG recordings, included serum levels of Insulin-like Growth Factor 1 (IGF-1), obstructive sleep-related breathing symptoms, as assessed by the Paediatric Sleep Questionnaire (PSQ), quality of life, as assessed by the OSA-18 questionnaire, and childhood behaviour, as assessed by the Behavioural Assessment System for Children (BASC-2) Behavioural and Emotional Screening System (BESS), and nocturnal enuresis. In addition, blood samples were collected at the end of each treatment period to assess growth hormone changes by measuring blood levels of insulin-like growth factor-1 (IGF-1).
Results: Compared to a Sham MAS, wearing an Active MAS resulted in a significant reduction in AHI of 40% (p=0.002) with a decrease in AHI when using the Active MAS, and a tendency for an increase in AHI when using the Sham MAS. The separate assessment of AHI in supine and non-supine sleeping positions revealed that only the former was significantly influenced by treatment, with a reduction of 4.1 events per hour (95% CI=1.8-6.4; p<0.001). Snoring time was 46.3 minutes shorter with the Twin-Block than with the Sham appliance (95% CI=14.5-78.1; p=0.004). The lowest oxygen saturation showed significant improvement of 3.4% (95% CI=0.9-5.9; p=0.007) with the Twin-block in comparison to the Sham MAS. Compared to a Sham MAS, the Active MAS also reduced SDB symptoms. Subjective assessment by parents showed significant improvement, as represented by PSQ, OSA-18, and BASC-2 scores (p≤0.028). IGF-1 levels, however, did not differ between the two treatment periods (p=0.172). There were no reports of nocturnal enuresis incidents during the study periods.
Conclusion: The short-term use of mandibular advancement splints significantly reduced AHI, supine AHI. The decrease in the overall AHI resulted from a combination of a decrease in AHI when using the Active MAS, and a tendency towards an increase in AHI when using the Sham MAS. Snoring time decreased significantly when using MAS in children with SDB, and participants showed improvement in subjectively assessed SDB symptoms and quality of life. In addition, significant improvement was detected in parent-reported child behaviour.