Three-Dimensional (3d) Morphological Evaluation of the Maxillary Arch and Its Relationship With Craniofacial Characteristics in Patients With Cleft Lip and Palate

Every human face is built on a delicate framework of bone, where the upper jaw, or maxilla, serves as the foundation for the teeth, the roof of the mouth, and the support for the nose. In most people, this structure grows in a smooth, predictable curve, forming a spacious arch that accommodates the teeth and allows the face to develop with balance. However, for children born with a cleft lip or palate, this natural growth is interrupted. A cleft is a gap in the tissue that occurs when the parts of the face that should fuse together during early development remain separate. This gap can range from a simple split in the lip to a complex separation that extends through the roof of the mouth. While surgeons can repair these gaps, the scars left behind and the altered growth patterns often leave the upper jaw smaller, narrower, or differently shaped than usual. Understanding exactly how these jaws look in three dimensions, and how those local shapes relate to the overall position of the skull, is crucial for doctors who plan treatments to help these children grow into healthy, functional adults.

For decades, doctors have relied on two-dimensional X-rays to map the skeletal structure of the face. These images provide a flat, side-view snapshot that is excellent for seeing how the upper and lower jaws align front-to-back. Yet, a flat image cannot capture the full volume of the roof of the mouth or the true width of the dental arch in a way that accounts for the complex, often asymmetrical shapes found in cleft patients. To bridge this gap, a team of researchers in Brazil turned to a more modern approach: they created detailed, three-dimensional digital models of the upper jaws of 132 children, aged seven to twelve, who had been treated for clefts at a specialized medical center. The team wanted to see if the specific shape and size of the roof of the mouth, measured in full 3D space, could tell them anything about the broader skeletal relationships of the face that are usually seen only on X-rays.

The researchers divided the children into three groups based on the type of cleft they had: those with a cleft lip only, those with a cleft lip and palate on one side, and those with a cleft lip and palate on both sides. Using high-resolution scanners, they captured the exact surface of the children's upper jaws and used computer software to measure the volume of the roof of the mouth, the length of the dental arch, and the distance between the teeth at the front and back of the arch. They then compared these 3D measurements against the children's standard X-rays, which showed the position of the jawbones relative to the skull. The goal was to determine if a smaller roof of the mouth or a shorter arch meant the jaw was positioned differently in the skull, or if these were separate issues that needed to be understood independently.

The results revealed clear differences between the groups. Children with clefts that involved the roof of the mouth had significantly smaller volumes in their palatal space and shorter dental arches compared to those with clefts limited to the lip. The roof of the mouth was also narrower in the middle section for these children. However, when the researchers looked at the width of the jaw near the back teeth, they found no significant difference between the groups. This suggests that the impact of the cleft and the subsequent surgery is not uniform; it shrinks the space and length of the arch more than it affects the width at the very back. When they compared these 3D shapes to the X-ray data, they found that the two types of measurements were related, but only loosely. A larger volume of the roof of the mouth or a longer arch did tend to correlate with a jaw that was positioned more forward in the skull, but the connection was not strong enough to predict one from the other with certainty.

This lack of a tight connection is actually a key finding. It indicates that the local shape of the upper jaw and the global position of the jawbone within the skull are distinct aspects of facial development. While they influence each other, they are not the same thing. The study showed that the length of the dental arch was the feature most likely to reflect the overall forward or backward position of the jaw, but even this relationship was only moderate. The width of the arch, particularly near the back teeth, showed almost no relationship to the side-view X-ray measurements, which makes sense because a side view cannot easily capture how wide the jaw is from left to right. The researchers concluded that relying on just one method, whether it is a flat X-ray or a 3D model, gives an incomplete picture. Instead, the most accurate way to understand a patient's facial structure is to use both tools together. The 3D models provide a precise map of the local space available for teeth and soft tissue, while the X-rays show how that space fits into the larger framework of the head. By combining these perspectives, doctors can better plan treatments that address both the immediate shape of the mouth and the long-term growth of the face.