Provided are a method and apparatus for processing an intraoral image. The data processing apparatus includes a memory including one or more instructions, and a processor configured to execute the one or more instructions stored in the memory, wherein the processor, by executing the one or more instructions, displays an eggshell generated based on surface data of a tooth selected from the intraoral image, provides a user interface that allows to adjust a boundary of the eggshell, and displays an eggshell transformed by adjusting the boundary of the eggshell according to a user input through the user interface.