To develop and validate a CBCT-based three-dimensional volumetric analysis method for assessing infrabony defect regeneration, overcoming limitations of conventional two-dimensional radiographic evaluation. Pre- and post-treatment CBCT scans (DICOM 3.0 format) from a case undergoing guided tissue regeneration were reconstructed using Mimics Research 21.0 and exported as STL files. Three-dimensional defect models were segmented and analyzed using Geomagic Wrap software, with standardized defect volume measurements obtained through a reproducible coordinate system. A reliable reference plane was established using adjacent dental anatomy, enabling consistent volumetric assessment across serial CBCT scans. Quantitative three-dimensional analysis revealed significant changes in infrabony defect volume following regenerative therapy, providing comprehensive evaluation of bone regeneration patterns. This novel volumetric assessment method offers clinicians and researchers an accurate three-dimensional alternative to traditional 2D imaging for evaluating periodontal regeneration outcomes, addressing critical limitations of conventional radiographic analysis.