How Thalassemia Affects Jaw and Facial Development: Insights from a Scoping Review

Synthesizing Decades of Craniofacial Research

Thalassemia is a hereditary blood disorder known to produce systemic health complications throughout the body. While healthcare providers have recognized that it can influence the growth of the face and jawbones, the precise morphological patterns of these alterations have remained incompletely characterized. Until recently, published clinical evidence was fragmented across isolated studies without a single comprehensive synthesis.

To address this gap, researchers performed a scoping review aimed at mapping and synthesizing the craniofacial and orthodontic changes seen in people with thalassemia. The authors gathered cross-sectional studies, cohort studies, and clinical trials from four electronic research databases alongside gray literature (research reports published outside traditional academic journals). In total, the review analyzed 26 studies published between 1964 and 2025, representing a combined total of 2,353 participants. Data from these papers were analyzed descriptively to highlight consistent skeletal and dental patterns.

Common Facial and Jaw Alterations

By examining data across the 2,353 participants, the review identified several recurring structural changes in the skull and jawbones:

• Class II skeletal pattern: A foundational jaw relationship where the upper jaw sits noticeably further forward than the lower jaw.
• Mandibular retrusion: A condition in which the mandible (the lower jawbone) is positioned further backward than normal.
• Maxillary protrusion: A structural feature where the maxilla (the upper jawbone) projects forward.
• Increased lower facial height: An elongation of the lower portion of the face.
• Thalassemic facies: A recognized group of facial physical features characteristic of the condition.

In addition to broad jawbone alterations, the review documented specific orthodontic anomalies affecting how the teeth fit together:

• Class II malocclusion: A misaligned bite where the upper front teeth significantly overlap the lower teeth.
• Anterior open bite: A vertical gap where the front upper and lower teeth fail to touch when closing the mouth.
• Crowding: Overlapping or misaligned teeth caused by a lack of space along the jaw.
• Incisor protrusion: Front cutting teeth that flare or lean outward.
• Transverse constriction of the arches: A physical narrowing of the skeletal dental arches.

Clinical Factors Influencing Severity

The synthesis revealed that these structural alterations were not uniform across all individuals. Greater severity of facial and dental changes was consistently linked to three underlying clinical factors: persistent chronic anemia, undergoing a splenectomy (the surgical removal of the spleen), and receiving delayed blood transfusions.

Study Limitations

The review highlighted several genuine limitations within the current body of research. The existing evidence remains fragmented across different study designs and patient groups. Furthermore, despite the frequency of these structural changes, therapeutic evidence is extremely sparse: only one study among the 26 evaluated functional appliance therapy (orthodontic devices that help guide jaw alignment). In that single study, functional appliances successfully improved lower jaw advancement and facial appearance. However, because intervention evidence comes from only one report, broader clinical trials are necessary to confirm these therapeutic outcomes.

What This Means for Patients

This review demonstrates that thalassemia can significantly shape facial development and tooth alignment. For individuals and families managing the condition, early orthodontic evaluation is an important step. Timely interceptive treatment during childhood growth can help guide jaw development, slow down the progression of facial deformities, and potentially decrease the need for complex orthognathic surgery (surgical realignment of the jawbones) later in life.