A method for generating a dental preparation guide configured for validating the preparation of at least one tooth for a dental restoration. A tooth is virtually removed from a digital 3D representation of the patient's pre-prepared set of teeth to form a digital 3D representation of a remaining set of teeth. A virtual target dental restoration expressing a target shape of the dental restoration is obtained and a virtual validation surface for the dental preparation guide is created based on the virtual target dental restoration, where the validation surface is such that the preparation of the tooth can be validated by the dental preparation guide. A virtual preparation guide surface is created by combining the virtual validation surface and part of the surface of the digital 3D representation of the remaining set of teeth.