Objective By comparing the Cone beam CT （CBCT） of bone class Ⅲ and normal occlusion， the difference of bony nasal base between them was compared to provide the basis for the diagnosis and treatment of nasal base depression. Methods From January 2020 to December 2023，40 patients （20 cases of bone class Ⅲ and 20 cases of normal occlusion） were selected， and the CBCT related data were measured and imported into Simplant pro 11.04 software for threedimensional fixed-point pointing， and the differences of nasal base between the two groups were compared. Results There

were statistically significant differences in the absolute/relative protrusion of the upper alveolar seat point， the absolute/

relative protrusion of the anterior nasal point， the absolute/relative protrusion of the bilateral paranasal and infraorbital points， the absolute/relative protrusion of the bilateral paranasal points， and the absolute/relative protrusion of the bilateral canine socket between the patients with bone class Ⅲ and the patients with normal combination （P<0.05）. Conclusion CBCT has certain significance in the auxiliary diagnosis of nasal base depression， and after three-dimensional reconstruction measurement， the points A， AN， B3， mid-ParaN-D-IF and ParaN of bony Ⅲ patients are moved back compared with those

of normal patients.

Nasal base, Cone beam CT, Three-dimensional measurement