## 2 Materials and Methods
### Data Source  
The first step in both the traditional fabrication of PNAM and the computer-aided design of PNAM appliances is to obtain an oral maxillary model of the child with cleft lip and palate, which serves as the basis for designing the appliance. As the initial step in PNAM treatment for newborns with cleft lip and palate, this study elaborates on the method for preparing the maxillary model using a cooperating agency. To prepare the maxillary model for cleft lip and palate, the facebow and articulator tool depicted in Figure 2A is required. The facebow and articulator consists of external auditory canal supporting balls, nasal support, a frame adjustment frame, fixing screw, vertical connecting rod, and bite jaw fork. Its primary function is to transfer the positional relationship between the maxilla and mandible to the facebow and articulator, thereby ensuring that the oral maxillary model is fixed in the appropriate position. The specific procedure for preparing the maxillary model is as follows [24]: First, ensure that the child is fully awake. Second, insert the two external auditory canal support balls of the facebow and articulator into the child's external auditory canal and support the nasal support at the root of the child's nose, so that the plane composed of the external auditory canal support ball and frame adjustment frame is at the orbital ear plane. Third, apply an appropriate amount of silicone rubber to the bite jaw fork and place it in the child's mouth, tilting the child's head gently and allowing them to cry freely to ensure they maintain adequate breathing during the molding process. Fourth, adjust the vertical connecting rod to slowly move the bite jaw upward, ensuring to keep it parallel with the orbital plane. Finally, once the silicone rubber has solidified, remove the jaw fork to obtain the child's oral maxillary model. Figure 1: Full-text structure diagram. Firstly, the alveolar bone model is extracted from the maxillary model, and then feature points are extracted from the alveolar bone model. The healthy side rotation and built-in algorithm are designed based on the extracted feature points. The maxillary 3D model obtained in this paper was further processed by 3D design software to obtain the STL format file of the alveolar bone part in the oral maxillary 3D model of the child. STL (stereolithography) is an interface protocol developed by 3D SYSTEMS in 1988, which is a 3D graphics file format for rapid prototyping technology. The STL file is composed of the definition of multiple triangular facets. The definition of each triangular facet includes the 3D coordinates of each fixed point of the triangle and the normal vector of the triangular facet. The STL file consists of binary format or ASCII code format. The maxillary 3D models involved in this study were stored in STL files in binary format. To read the coordinate data of the maxillary 3D model from the STL file, one must understand the form and composition of the data in the STL file. The specific composition of the STL file in binary format is as follows:  
1. Part 1, 84 bytes: The first 80 bytes are file headers, storing information such as file name; the last 4 bytes are integers describing the number of triangular patches of the model;
2. Part 2: The geometric information of all triangles is stored in order. Each triangle occupies 50 bytes, which also has its composition, followed by: Part 1, three 4-byte floating point numbers, a total of 12 bytes, storing the x, y, and z coordinates of the triangle normal vector; Part 2, three 4-byte floating point numbers, 12 bytes in total, storing the x, y, and z coordinates of vertex 1 of the triangle; Part 3, three 4-byte floating point numbers, 12 bytes in total, storing the x, y, and z coordinates of vertex 2 of the triangle; Part 4, three 4-byte floating point numbers, 12 bytes in total, storing the x, y, and z coordinates of vertex 3 of the triangle.