Role of STL Files and CBCT Data in Surgical Guide Design
Every surgical guide begins as two separate digital files captured at different times with different equipment: a CBCT scan stored in DICOM format, and an intraoral scan stored in STL format. Neither file alone is sufficient for guide design. Together, when properly aligned through registration, they form the complete three-dimensional patient model that guides the entire design process.
CBCT Data: The Sub-Surface Blueprint
What CBCT Captures
Cone beam computed tomography captures the three-dimensional internal anatomy of the jaw. The CBCT dataset provides bone anatomy in three dimensions including cortical plates and ridge contours, the inferior alveolar nerve canal's complete three-dimensional path, maxillary sinus anatomy and floor height, positions and angulations of adjacent tooth roots, bone density Hounsfield Unit values, and pathological findings such as cysts or bone defects.
DICOM Format
CBCT data is stored in DICOM format, the international standard for medical imaging. A CBCT DICOM dataset consists of hundreds to thousands of individual slice files representing cross-sections through the jaw, typically 0.1 to 0.4mm apart. Planning software stacks these slices and reconstructs the three-dimensional volume for implant planning.
What CBCT Cannot Capture
CBCT does not accurately capture tooth crown surfaces, gingival margins, or soft tissue contours. For surgical guide design, we need both: CBCT provides the bone data, while the intraoral scan provides the surface data that determines guide fit.