The clinical challenge of Apert syndrome: between facial hypoplasia and complex rehabilitation

Apert syndrome, or type I acrocephalosyndactyly, represents approximately 4.5% of craniosynostosis cases, with an estimated prevalence of 1 in 65,000 live births. For the dental surgeon and the oral and maxillofacial surgery (OMFS) specialist, this genetic pathology (mutations of the FGFR2 gene, notably Ser252Trp and Pro253Arg) requires management of rare complexity. Severe midface hypoplasia, characteristic of the syndrome, creates a restrictive environment for dento-alveolar development, manifesting as Class III malocclusions, massive dental crowding, delayed eruption, and upper airway obstructions that can lead to sleep apnea.

The objective of this narrative review is to synthesize current concepts in the dental and maxillofacial management of these patients, focusing specifically on the surgical timing, the limitations of orthodontics in the face of skeletal dysplasias, and the integration of digital workflows. The study examines the hypothesis that a sequenced multidisciplinary approach — beginning with early cranial expansion followed by Le Fort III midface advancement between 6 and 10 years of age — optimizes functional and aesthetic outcomes. The authors also evaluate current controversies surrounding surgical sequencing and the management of palatal pseudoclefts in a context of stable occlusal rehabilitation.

Narrative review methodology

The authors of this narrative review conducted an exhaustive literature search between May and August 2025 to synthesize the clinical challenges associated with Apert syndrome. The analysis was based on the interrogation of five electronic databases: PubMed, Scopus, Web of Science, Google Scholar, and Wiley Online Library.

• Selection criteria: The study included works published from the year 2000 onwards to ensure the relevance of current diagnostic and therapeutic approaches. Priority was given to high-impact systematic reviews, clinical practice guidelines, and significant case reports published after 2010.
• Search strategy: The keywords used targeted genetic (FGFR2), surgical (craniosynostosis, Le Fort, surgical management) and odontostomatological (dental management, orthodontic, occlusion, pediatric dentistry) aspects.
• Exclusion criteria: Animal studies, conference abstracts and publications not directly related to the multidisciplinary management objectives were excluded.
• Data synthesis: The information collected was subject to a qualitative synthesis structuring the therapeutic framework according to the patient's developmental stages, referring in particular to the chronological classification of Fadda et al. (from birth to adulthood).

Clinical synthesis results on Apert syndrome

Reported epidemiological data indicate that Apert syndrome accounts for approximately 4.5% of diagnosed craniosynostosis cases, with an estimated prevalence of 1 in 65,000 live births. The etiology is genetic, linked to mutations in the FGFR2 (Fibroblast Growth Factor Receptor-2) gene. Two specific mutations predominate and are associated with distinct clinical characteristics:

FGFR2 mutation	Observed clinical correlations
Ser252Trp	High rates of cleft palates.
Pro253Arg	Stronger association with syndactyly of the extremities.

The analysis of stomatognathic manifestations highlights severe midface hypoplasia, resulting in skeletal Class III malocclusion, massive dental crowding, and eruption anomalies. Functionally, upper airway obstruction is frequently reported, often leading to obstructive sleep apnea.

Surgical and orthodontic management is organized according to a therapeutic sequence divided into three stages of development:

• Initial stage (from birth to two years): Focus on early cranial expansion via fronto-orbital advancement (FOA) or posterior vault distraction osteogenesis (PVDO) to stabilize intracranial pressure.
• Development stage (up to twelve years): Correction of midfacial hypoplasia by Le Fort III osteotomy combined with distraction osteogenesis.
• Adult stage: Finalization of occlusal rehabilitation through orthognathic surgery.

The authors emphasize that early maxillary expansion using palatal appliances encounters major technical obstacles. The specific morphology of the palate, characterized by a deep ogival arch and the presence of a pseudo-cleft, complicates the adaptation and stabilization of conventional orthodontic devices.

Clinically, the results of this review confirm that the management of Apert syndrome can only be multidisciplinary, where each surgical stage conditions orthodontic success. Midfacial hypoplasia remains the main bottleneck: it generates obstructive sleep apnea and skeletal open bites that orthodontics alone cannot compensate for. The study highlights that while midface advancement (Le Fort III) significantly improves respiratory function and occlusion, it requires perfect coordination with orthodontic preparation. The limitations of this review lie in the very nature of the pathology: the rarity of cases limits the production of studies with a high level of evidence (randomized trials). The literature remains dominated by case series and institutional protocols. Furthermore, although the integration of digital workflows is mentioned as a future path for surgical planning, the authors note that its systematic deployment is still subject to debate regarding its cost-benefit ratio and standardization. For the practitioner, these data serve as a reminder that long-term success depends on growth management. Early interventions do not prevent future malocclusions, which necessitates constant follow-up until adulthood to finalize occlusal rehabilitation through orthognathic surgery.

Summary of results

This narrative review reports that Apert syndrome, affecting 1 in 65,000 births, requires sequenced multidisciplinary management. The strategy is based on early cranial expansion (FOA between 8-12 months or PVDO between 3-16 months) followed by midfacial advancement (Le Fort III with distraction) during childhood or adolescence to treat maxillary hypoplasia and severe skeletal Class III malocclusions.

In concrete terms, for the practitioner:

• Anticipate expansion failures: The effectiveness of conventional palatal expanders is limited by the irregular morphology of the palate and the presence of a pseudo-cleft; the use of digital workflows and custom-made devices is strongly suggested.
• Provide for respiratory monitoring: Midface hypoplasia is a major risk factor for obstructive sleep apnea; clinical vigilance is required from the dental practice to the maxillofacial surgery unit.
• Imperative early coordination: Initial cranial interventions do not prevent malocclusions; inform parents that complex orthodontic treatment and orthognathic surgery will still be necessary during adolescence.

Technical lexicon of Apert syndrome

FGFR2 (Fibroblast Growth Factor Receptor-2): Gene encoding a fibroblast growth factor receptor. Mutations in this gene (primarily Ser252Trp and Pro253Arg) are responsible for the disruption of craniofacial and skeletal osteogenesis characteristic of the syndrome.

Craniosynostosis: Premature fusion of one or more cranial sutures. In Apert syndrome, this pathological process restricts skull growth, requiring decompression interventions to prevent intracranial hypertension.

Syndactyly: Congenital fusion of the fingers and/or toes present in patients with Apert syndrome. It is often accompanied by reduced mobility due to the progressive ossification of the interphalangeal joints.

Fronto-orbital advancement (FOA): Surgical procedure consisting of the advancement of the frontal bone and superior orbital rim, generally performed between 8 and 12 months, to protect ocular structures and restore the anterior cranial contour.

Posterior vault distraction osteogenesis (PVDO): A posterior cranial expansion technique performed between 3 and 16 months. It is increasingly preferred for its ability to effectively increase intracranial volume and control cerebral pressure.

Midface hypoplasia: Developmental defect of the upper and middle facial skeleton, leading to ocular proptosis, skeletal Class III malocclusion, and upper airway obstruction.

Pseudocleft palate (Pseudocleft): Morphological anomaly of the palate characterized by a narrow and high vault with a deep median groove. This structure complicates the adaptation of palatal expansion appliances during orthodontic treatment.

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