Method and terminal device for providing tooth deterioration information to user

A method for diagnosing conditions of teeth using an oral diagnostic device, the method comprising:

• irradiating light, which is generated by an optical transmitting member of the oral diagnostic device, to each tooth of a user;
• receiving, by an optical receiving member of the oral diagnostic device, the light reflected from the each tooth;
• determining a first tooth state numerical value for the each tooth of the user based on first information associated with the each tooth, wherein the first information is obtained based on the light reflected from the each tooth during a first measurement period;
• receiving tooth self-management information from the user at least once during a non-measurement period between the first measurement period and a second measurement period, which is after the first measurement period;
• calculating tooth self-management performance rating for the user in the non-measurement period based on the received tooth self-management information;
• determining a second tooth state numerical value for the each tooth of the user based on second information associated with the each tooth of the user, wherein the second information is obtained based on the light reflected from the each tooth during the second measurement period using the oral diagnostic device;
• selecting at least one target tooth which was not treated in the non-measurement period;
• calculating a difference between the second tooth state numerical value and the first tooth state numerical value for each of the at least one target tooth;
• calculating a weighted difference for each of the at least one target tooth based on the difference and a weight assigned for each of the at least one target tooth;
• and
• obtaining tooth deterioration information of the user at the second measurement period based on the weighted difference for each of the at least one target tooth.