A method of evaluating an oral condition, the method comprising: comparing a first digital representation of at least a portion of an oral cavity of a first patient to a second digital representation of the portion of the oral cavity of the first patient, the first digital representation being representative of the portion of the oral cavity at a first time and the second digital representation being representative of the portion of the oral cavity at a second time, the second time being subsequent to the first time; automatically identifying at least one clinically-significant difference between the first digital representation and the second digital representation, said clinically-significant difference being for example a change in position of at least one tooth, a change in a position of a gum line a change in tooth shape, or a change in color of at least one tooth; and displaying the first digital representation, the second digital representation or a combination of the first digital representation and the second digital representation in a way that highlights the at least one clinically-significant difference; characterised by determining a magnitude of said clinically-significant difference; and by displaying an overlaid color-coding indicative of a degree of change of the clinically-significant difference at different locations in the oral cavity, wherein displaying the overlaid color-coding includes displaying a first portion of the oral cavity in a first color when the magnitude of the said clinically-significant difference exceeds a threshold at the first portion of the oral cavity, and wherein displaying the overlaid color-coding includes displaying a second portion of the oral cavity in a second color when the magnitude of said clinically-significant difference does not exceed a threshold at the second portion of the oral cavity. comparing a first digital representation of at least a portion of an oral cavity of a first patient to a second digital representation of the portion of the oral cavity of the first patient, the first digital representation being representative of the portion of the oral cavity at a first time and the second digital representation being representative of the portion of the oral cavity at a second time, the second time being subsequent to the first time; automatically identifying at least one clinically-significant difference between the first digital representation and the second digital representation, said clinically-significant difference being for example a change in position of at least one tooth, a change in a position of a gum line a change in tooth shape, or a change in color of at least one tooth; and displaying the first digital representation, the second digital representation or a combination of the first digital representation and the second digital representation in a way that highlights the at least one clinically-significant difference; characterised by determining a magnitude of said clinically-significant difference; and by displaying an overlaid color-coding indicative of a degree of change of the clinically-significant difference at different locations in the oral cavity, wherein displaying the overlaid color-coding includes displaying a first portion of the oral cavity in a first color when the magnitude of the said clinically-significant difference exceeds a threshold at the first portion of the oral cavity, and wherein displaying the overlaid color-coding includes displaying a second portion of the oral cavity in a second color when the magnitude of said clinically-significant difference does not exceed a threshold at the second portion of the oral cavity.