Introduction
Pierre Robin Sequence (PRS), described in 1923 by French dentist Pierre Robin, is characterised by a combination of mandibular micrognathia, glossoptosis and wide U-shaped cleft palate that may vary in severity.Reference Müller-Hagedorn, Buchenau, Arand, Bacher and Poets1, Reference Naros, Bartel, Bacher, Koos, Blumenstock and Wiechers2 This condition can occur in isolation or along with syndromes or other malformations, the common ones being Stickler syndrome, Nager syndrome or Treacher Collins syndrome.Reference Choo, Khosla, Meister, Wan, Lin and Feczko3–Reference Ho, Wong, Cheung, Ng, Siu and Fung5 The main issues faced by infants with PRS include intermittent hypoxia and obstructive sleep apnoea (OSA) caused by upper airway obstruction (UAO), as well as feeding difficulties.Reference Choo, Galera, Balakrishnan, Lin, Ahn and Lorenz6
In addition to airway issues, these infants also face other complications, including feeding difficulties due to reduced weight gain and failure to thrive,Reference Naros, Bartel, Bacher, Koos, Blumenstock and Wiechers2 which can subsequently lead to neurocognitive impairment, behavioural difficulties and even comorbidities, such as pulmonary hypertension or congestive heart failure.Reference Müller-Hagedorn, Buchenau, Arand, Bacher and Poets1 The feeding problems among these infants may be secondary to respiratory issues, such as increased breathing effort, or result from swallowing dysfunction or abnormal sucking quality.Reference Müller-Hagedorn, Buchenau, Arand, Bacher and Poets1 Therefore, the primary therapeutic goals are to improve the respiratory situation and achieve good weight gain.
Various treatment modalities, including non-surgical and surgical interventions, have been advocated in patients having PRS to ensure survival in their early life, as UAO can be potentially life threatening, and the co-existing cleft palate may further compromise their nutritional intake secondary to feeding difficulties.Reference Buchenau, Wenzel, Bacher, Müller-Hagedorn, Arand and Poets7, Reference Naros, Steiner-Wilke, Kaiser, Bacher, Koos and Blumenstock8 Other than watchful waiting, non-surgical options such as prone positioning, nasopharyngeal airway insertion and continuous positive airway pressure (CPAP) are described in the literature.Reference Naros, Steiner-Wilke, Kaiser, Bacher, Koos and Blumenstock8 These, however, may entail risks or drawbacks. For example, a prone position may increase the risk of sudden infant death syndrome (SIDS), while long-term application of CPAP may suppress facial growth.Reference Choo, Galera, Balakrishnan, Lin, Ahn and Lorenz6 It may also be challenging to find a suitable-sized nose or mouthpiece for a small baby when considering CPAP use. Mandibular distraction osteogenesis (MDO) is currently the preferred surgical intervention for infants with moderate to severe PRS.Reference Marcus and Scott9 However, its long-term effects on temporomandibular joint (TMJ) function remain uncertain, given the bidirectional forces applied at the osteotomy site. In addition, MDO carries risks such as injury to developing tooth buds and nerves, potential complications from general anaesthesia, blood loss and facial scarring.Reference Choo, Khosla, Meister, Wan, Lin and Feczko3, Reference Choo, Galera, Balakrishnan, Lin, Ahn and Lorenz6, Reference Marcus and Scott9
Orthodontic airway plate (OAP), first described by Pielou in 1967, is a non-invasive functional treatment that works by relieving UAO and separating the nasal and oral cavities in cases with cleft palate, while at the same time thought to be able to promote mandibular catch-up growth.Reference Buchenau, Wenzel, Bacher, Müller-Hagedorn, Arand and Poets7, Reference Schmidt, Hirschfelder, Heiland and Matuschek10, Reference Wiechers, Buchenau, Arand, Oertel, Peters and Müller-Hagedorn11 It is an intra-oral device that covers the palate and alveolar ridges with velar extension to displace the base of the tongue forward, held in place by suction and adhesive. Some may require an extra-oral extension of wire bows to help retain the baby’s face using adhesive tape. It is known as either the Tübingen palatal plate (TPP) or the pre-epiglottic baton plate (PEBP).Reference Naros, Steiner-Wilke, Kaiser, Bacher, Koos and Blumenstock8 With the device in place, the tongue is shifted anteriorly, widening the hypopharynx and releasing the UAO.
With improvements in the technique of OAP construction and adjustment, we would like to review its outcomes in airway, speech and swallowing, thereby encouraging its use as an alternative to invasive ventilatory support in infants with PRS. This systematic review aimed to cover the current literature available on the outcomes of OAP in children with PRS.
Materials and methods
We conducted a systematic review of the literature in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelinesReference Page, McKenzie, Bossuyt, Boutron, Hoffmann and Mulrow12 to identify studies reporting outcomes of conventional OAPs in neonates with PRS.
This review adopted the Population, Intervention, Comparison, Outcomes and Study (PICOS) framework, which included paediatric and adolescent patients diagnosed with PRS under eighteen years of age. The intervention planned is OAP. Comparators are any alternative medical or surgical methods or none. Outcomes are classified as primary outcome: improvement in symptoms: airway, swallowing; secondary outcome: persistence of symptoms or presence of complications.
Data sources and searches
PubMed, Scopus, Embase and Google Scholar databases were searched to identify studies published between inception and 31 December 2024. Only articles published in the English language were included. The following key terms were searched either individually or in combination: orthodontic airway; oral appliance; Pierre Robin Sequence; airway plate; micrognathia; airway adjunct; children; paediatric; child; airway intervention.
Figure 1 provides detailed information on the search strategy. In order to ensure a robust search procedure, references of the included studies were also included. Duplicate studies were excluded using EndNote X8 software (Clarivate, London, United Kingdom). The search was conducted over a period of one month (January 2025) in accordance with the PRISMA guidelines. After being scrutinised by the panel members, 10 original clinical research articles were selected in accordance with our objective and selection criteria.
PRISMA flow diagram showing search criteria.
Study selection
Articles of interest were screened independently based on the title and abstract to identify eligible studies, followed by the independent full text of two authors (CS and KS). Any disagreements regarding the inclusion of articles were resolved by consensus or through discussion with a third author (JS).
Conference abstracts, letters to editors, commentaries, review articles, publications without peer review and grey literature were excluded. No restrictions were placed on sample size, as the evidence for OAPs is limited.
Data extraction
Two authors independently extracted data. We extracted the following information from each eligible study and entered it into a predefined Excel (Microsoft, Redmond, Washington, USA) spreadsheet: the first author’s last name, study design, participants’ country, total number of patients, age, gender, clinical manifestations, underlying comorbidities, investigations, type of OAP, outcome and presence of complications.
Outcome measures
The primary outcome was defined as the intervention’s success, determined by improvement in symptoms. Secondary outcomes included symptom persistence or worsening and the presence of complications. Studies that did not report outcome data were excluded.
Ethical considerations
The study was performed in accordance with ethical standards. The authors declare no conflict of interest.
Quality assessment
The quality of the included studies was assessed independently by two authors using the Joanna Briggs Institute (JBI) critical appraisal tools. The studies were classified as low, moderate and high quality if the overall score was less than or equal to 49 per cent, 50–69 per cent, or greater than or equal to 70 per cent.13
Results
Table 1 shows the 10 articles included that fulfilled our inclusion and exclusion criteria.Reference Müller-Hagedorn, Buchenau, Arand, Bacher and Poets1, Reference Naros, Bartel, Bacher, Koos, Blumenstock and Wiechers2, Reference Ho, Wong, Cheung, Ng, Siu and Fung5, Reference Buchenau, Wenzel, Bacher, Müller-Hagedorn, Arand and Poets7, Reference Naros, Steiner-Wilke, Kaiser, Bacher, Koos and Blumenstock8, Reference Schmidt, Hirschfelder, Heiland and Matuschek10, Reference Wiechers, Buchenau, Arand, Oertel, Peters and Müller-Hagedorn11, Reference Poets, Maas, Buchenau, Arand, Vierzig and Braumann14–Reference Wiechers, Uhlig, Poets, Weise, Naros and Krimmel16 There were 598 patients with PRS, among which 80.7 per cent of infants had isolated PRS (n = 483), and 115 infants had an underlying syndromic Robin sequence. We found that the syndromic group included children with Stickler syndrome, cat eye syndrome and 4q deletion syndrome. Although cleft palate is a known feature associated with PRS, only 46 per cent of the infants had cleft palate.
Summary of main findings; A = airway; S = swallowing; Sp = speech; dx = diagnosis; f = female; m = male; PRS = Piere Robin Sequence; RS = Robin Sequence; iRS = isolated Robin Sequence; sRS = syndromic Robin Sequence; DoL = day of life; mo = month-old; MOAI = mixed obstructive apnoea index; OAI = obstructive apnoea index; CPAP = continuous positive airway pressure; HFNC = high-flow nasal cannula; NPA = nasopharyngeal airway; NG = nasogastric; NGT = nasogastric tube; OPA = orpharyngeal airway; OAP = orthodontic airway plate; PEBP = pre-epiglottic baton plate; CP = cleft palate; TPP = Tübingen palatal plate; PSG = polysomnography; OSA = obstructive sleep apnoea; OSAS = obstructive sleep apnoea syndrome; UAO = upper airway obstruction; NA = not available; dx = diagnosis
In 8 out of 10 studies, an obstructive apnoea index (OAI) of more than 3 was the criterion for starting OAP treatment. In two studies, OAP was the treatment of choice for all PRS patients,Reference Müller-Hagedorn, Buchenau, Arand, Bacher and Poets1, Reference Buchenau, Wenzel, Bacher, Müller-Hagedorn, Arand and Poets7 regardless of OSA findings. Besides OAP, other concurrent treatments include nasopharyngeal or endotracheal intubation, glossopexy, tracheostomy and non-invasive ventilation, such as positive pressure ventilation or nasal cannula oxygen, as well as nasopharyngeal airway placement and patient positioning in the prone position.
Five of the eight studies incorporated the Castillo-Morales prosthesis for stimulation of the oral musculatures and feeding training.Reference Buchenau, Wenzel, Bacher, Müller-Hagedorn, Arand and Poets7 Improvement was seen in the mixed obstructive apnoea index (MOAI) of all patients treated for UAO, except six children who required tracheostomy,Reference Wiechers, Buchenau, Arand, Oertel, Peters and Müller-Hagedorn11 one requiring CPAP,Reference Ho, Wong, Cheung, Ng, Siu and Fung5 and four children requiring supplemental high-flow nasal cannula (HFNC) post-treatment.
Among the 6 studies that included feeding as the outcome assessed post-treatment, 19 patients required Ryle’s tube feeding despite OAP, of which 11 were syndromic. Only 2 out of the 10 studies assessed the patients’ speech improvement post-OAP usage. Both these studies compared infants with cleft palate, with or without PRS. Their results showed good speech development in all their PRS patients with hypernasality, as seen within the group of patients with PRS.
Quality assessment of the included studies is summarised in Table 2. All the included papers were identified as high quality.
Quality assessment of the included cross-sectional studies
1. Were the criteria for inclusion in the sample clearly defined? 2. Were the study subjects and the setting described in detail? 3. Was the exposure measured in a valid and reliable way? 4. Were objective standard criteria used for measurement of the condition? 5. Were confounding factors identified? 6. Were strategies to deal with confounding factors stated? 7. Were the outcomes measured in a valid and reliable way? 8. Was appropriate statistical analysis used? Y=Yes; N=No; U=Unclear.
Discussion
Orthodontic airway plate has emerged as a non-invasive alternative to traditional surgical interventions in infants with PRS. A recent systematic analysis revealed that about two-thirds (65.8 per cent) of infants with PRS were managed using non-operative methods. Nasopharyngeal airways and infant positioning were the most commonly used non-operative interventions, likely due to their simplicity and low risk. Notably, orthodontic appliances emerged as the second most frequently reported modality, highlighting their increasing role in non-surgical management.Reference Haas, Yuen, Farrokhyar, Aminnejad, Williams and Choi17
Orthodontic airway plate has been advocated to correct airway obstruction and feeding difficulties without resorting to invasive procedures. It improves the airway by anteriorly repositioning the tongue and mandible, widening the hypopharyngeal space and subsequently reducing airway obstruction.Reference Ho, Wong, Cheung, Ng, Siu and Fung5, Reference Schmidt, Hirschfelder, Heiland and Matuschek10, Reference Poets, Maas, Buchenau, Arand, Vierzig and Braumann14, Reference Naros, Krimmel, Zengerle, Bacher, Koos and Mack15 The OAP stabilises the pharyngeal airway immediately upon initiation of treatment, offering swift respiratory relief.Reference Wiechers, Uhlig, Poets, Weise, Naros and Krimmel16 On the other hand, feeding is generally improved by preventing the tongue from collapsing into the airway during swallowing, which is crucial for neonates with impaired suck-swallow-breath co-ordination.Reference Choo, Khosla, Meister, Wan, Lin and Feczko3, Reference Buchenau, Wenzel, Bacher, Müller-Hagedorn, Arand and Poets7 This subsequently supports infant growth and improves overall health before cleft palate surgery, thus reducing peri-operative complications.Reference Naros, Krimmel, Zengerle, Bacher, Koos and Mack15
Poets et al.Reference Poets, Koos, Reinert and Wiechers18 identified only one randomised controlled trial evaluating treatment among PRS patients, comparing the TPP with a sham treatment (a conventional palatal plate). In 11 infants, the TPP significantly reduced the MOAI, while the sham plate had no effect.Reference Buchenau, Urschitz, Sautermeister, Bacher, Herberts, Arand and Poets19 A follow-up longitudinal study also showed significant improvements in MOAI over three months, along with successful transition to full oral feeding and good weight gain, with all infants discharged without feeding tubes.Reference Poets, Koos, Reinert and Wiechers18 It is thought that OAP facilitates oral feeding with the use of the baby’s own modified oral structures via altered tongue position, which also helps to reduce the size of the cleft palate on long-term application. The anterior positioning of the tongue allows medial growth of the palatal shelves with no obstruction, while the active tongue movement secondary to possible oral feeding with OAP may promote mandibular growth. This may be supported by the functional matrix theory in association with the tension generated within the TMJ capsule, through physiological bone remodelling.Reference Choo, Khosla, Meister, Wan, Lin and Feczko3, Reference Choo, Galera, Balakrishnan, Lin, Ahn and Lorenz6 The bone remodelling in the glenoid fossa speeds up, allowing the condyle’s forward position to become permanent as the infant’s orofacial structures continue to grow forward and downward.Reference Choo, Khosla, Meister, Wan, Lin and Feczko3 The available studies suggested that TPP treatment may reduce UAO by encouraging mandibular catch-up growth. However, it remains uncertain whether this growth is enough to provide a permanent resolution of airway obstruction in PRS.Reference Poets, Koos, Reinert and Wiechers18
Orthodontic airway plate has also been used in infants who have failed in response to prone positioning,Reference Schmidt, Hirschfelder, Heiland and Matuschek10 or in moderate to severe OSA for which CPAP is inadequate to address the issue.Reference Ho, Wong, Cheung, Ng, Siu and Fung5, Reference Poets, Maas, Buchenau, Arand, Vierzig and Braumann14 The presence of OSA, which indicated the use of OAP, was confirmed by the results of polysomnographic (PSG) sleep studies that show a MOAI of more than three events per hour. Additionally, the presence of severe micrognathia and glossoptosis may also be an indication to begin OAP therapy.Reference Naros, Krimmel, Zengerle, Bacher, Koos and Mack15 The intended function of this device was to alleviate UAO during the critical early months of life, preventing long-term complications such as neurocognitive delays or behavioural problems.Reference Wiechers, Uhlig, Poets, Weise, Naros and Krimmel16 Resnick et al.,Reference Resnick, de Gijsel, Jindal, Quante, Poets and Katz20 however, in their studies, found that MDO had significantly better outcomes in resolving severe UAO compared to OAP, while similar results were seen in infants of moderate UAO treated with both measures.
Prompt resolution of UAO, proper positioning of the tongue, advancement of the mandible, and timely repair of the cleft palate – facilitated by the PEBP – are essential for normalising jaw relationships and supporting the proper development of oral motor skills and speech.Reference Schmidt, Engeli, Matuschek, Hunn-Stohwasser, Bestendonk and Heiland21 Early intervention with the OAP has consistently yielded superior outcomes, with all studies recommending its use during the neonatal period.Reference Müller-Hagedorn, Buchenau, Arand, Bacher and Poets1, Reference Naros, Bartel, Bacher, Koos, Blumenstock and Wiechers2, Reference Wiechers, Uhlig, Poets, Weise, Naros and Krimmel16 It can be applied as early as a few hours to days after birth, once the issue is diagnosed, and typically discontinued six to eight months after facial harmonisation.Reference Müller-Hagedorn, Buchenau, Arand, Bacher and Poets1 This improves patient adaptation and reduces treatment duration due to the mandible’s growth potential in infancy.Reference Ho, Wong, Cheung, Ng, Siu and Fung5 Naros et al. maintained the use of OAP until around ten months of age, at which point the baby would undergo cleft palate repair surgery.Reference Naros, Krimmel, Zengerle, Bacher, Koos and Mack15 Additionally, PEBP effectively reduced cleft width by an average of 41.3 per cent by the time of surgical repair, a crucial factor for successful cleft palate closure and favourable long-term outcomes.Reference Schmidt, Engeli, Matuschek, Hunn-Stohwasser, Bestendonk and Heiland21
The effectiveness of OAP can be assessed using a combination of clinical observations, endoscopic evaluations and sleep studies. Polysomnographic sleep studies would help objectively evaluate progress or changes following OAP use, while clinical observations include the baby’s ability to regain oral feeding rather than tube feeding.Reference Ho, Wong, Cheung, Ng, Siu and Fung5, Reference Schmidt, Hirschfelder, Heiland and Matuschek10, Reference Poets, Maas, Buchenau, Arand, Vierzig and Braumann14, Reference Naros, Krimmel, Zengerle, Bacher, Koos and Mack15 The changes from tube to oral feeding upon discharge have also been proved in literature.Reference Resnick, de Gijsel, Jindal, Quante, Poets and Katz20 Weight gain was also carefully tracked to assess nutrition and overall growth improvements after starting on OAP.Reference Müller-Hagedorn, Buchenau, Arand, Bacher and Poets1, Reference Choo, Galera, Balakrishnan, Lin, Ahn and Lorenz6 Improved oral intake was a key marker of treatment success.Reference Naros, Krimmel, Zengerle, Bacher, Koos and Mack15 Meanwhile, nasopharyngoscopy was performed to evaluate the mechanical changes in the airway.Reference Müller-Hagedorn, Buchenau, Arand, Bacher and Poets1 In addition, serial imaging or clinical assessments are conducted to document mandibular catch-up growth, a long-term goal of treatments like OAP.Reference Choo, Galera, Balakrishnan, Lin, Ahn and Lorenz6, Reference Naros, Steiner-Wilke, Kaiser, Bacher, Koos and Blumenstock8
Studies demonstrated that OAP could avoid the need for tracheostomy, especially among isolated PRS.Reference Ho, Wong, Cheung, Ng, Siu and Fung5, Reference Buchenau, Wenzel, Bacher, Müller-Hagedorn, Arand and Poets7, Reference Schmidt, Hirschfelder, Heiland and Matuschek10, Reference Naros, Krimmel, Zengerle, Bacher, Koos and Mack15 Choo et al., in their study involving 16 subjects, found that PSG parameters improved for all subjects, with avoidance of tracheostomy or MDO following the use of OAP.Reference Choo, Sidell, Kim, Ahn, Day and Sullivan4 One study demonstrated that only a minority of syndromic PRS patients (4 per cent) require tracheostomy even with OAP.Reference Müller-Hagedorn, Buchenau, Arand, Bacher and Poets1 The need for post-operative airway interventions, such as nasopharyngeal airways, was also reduced with pre-operative OAP application among PRS patients.Reference Naros, Krimmel, Zengerle, Bacher, Koos and Mack15 The avoidance of invasive procedures is the main advantage of using the OAP. Abbas et al.,Reference Abbas, Lavin, Fahy, Choo, Truong and Bruckman22 in a systematic review, though demonstrating comparable outcomes in airway and feeding improvement in both MDO and OAP groups, stated that the results needed to be carefully evaluated due to disparities in symptom severity among infants treated with both MDO and OAP. Also, the significant difference in cohort sample size between the two groups may indicate a lack of representation of the results in the OAP group.
Several limitations of this study include heterogeneity, short follow-up periods, publication bias and gaps in the literature among the selected studies. The significant variation in study designs, ranging from retrospective to prospective observational studies, makes direct comparisons challenging. Additionally, the patient populations are highly heterogeneous, including both isolated and syndromic PRS cases with varying comorbidities. This diversity limits the generalisability of the findings. Another key limitation is the relatively short follow-up duration in most studies, with many only tracking outcomes for a few months. This is insufficient to assess long-term airway stability, feeding and speech development, or late-onset complications. While a few studies have longer follow-ups (up to 5–6 years), they are the exception rather than the norm.
Furthermore, publication bias is evident, as most studies originate from Germany, reducing applicability to broader healthcare settings. Additionally, the predominance of positive outcomes reported, along with a lack of randomised controlled trials, raises concerns about selective reporting. A notable literature gap is the limited focus on speech outcomes, as most studies primarily assess airway and swallowing improvements, while neglecting long-term speech development. Given that many patients with PRS have cleft palates, which can significantly impact articulation and resonance, further research is needed to evaluate the effects of different interventions on speech outcomes. These factors collectively highlight the need for more standardised, long-term and geographically diverse research that includes comprehensive speech assessments to establish stronger evidence for clinical interventions.
Conclusion
The OAP offers an effective, non-invasive treatment option for managing airway obstruction and feeding difficulties in neonates with PRS. The success of these treatments highlights the importance of early diagnosis, timely intervention and careful monitoring through PSG and weight assessments. Long-term outcomes of improved UAO, demonstrated by normal neurocognitive development, have proved the effectiveness of the OAP. Overall, the OAP represents a minimally invasive and effective approach for managing the airway complications associated with PRS.
Financial support
This research received no specific grant from any funding agency, commercial or not-for-profit actors.
Conflict of interest
All authors have no conflict of interest.
Ethical statement and informed consent
The study was conducted in accordance with the Declaration of Helsinki. The requirement for informed consent was waived because of the retrospective design.
Acknowledgement
All patients and parents involved
