Objective: An orthodontic treatment planning program in a specific society requires information on the orthodontic treatment needs of the population. The aims of this study were to compare the student, parent and clinician normative need and demand for orthodontic treatment between 12 and 17 years old groups in a sample of Iranian students using the IOTN.
Material and Methods: A sample of 846 students including 419 students of 12 years old and 427 students of 17 years old was selected randomly from schools in Abade. A questionnaire of family socioeconomic status was proposed to the parents. All the students were examined according to the Aesthetic and Dental Health components (AC and DHC) of Index of Orthodontic Treatment Need. Students' and parents' perceived need was also assessed using AC. Then the measurements of IOTN in both groups were compared in each component and the demands of each group were also compared with each other.
Results: According to DHC classification, 22.3% of 12 years old students and 18.7% of 17 years old students were categorized in the "no need" group; 29.5% of 12 years old and 35.6% of 17 years old students in the "border line" group and 48.2% of 12 years old group and 45.7% of 17 years old group in the "definite need" group. According to AC, in 12 years old students, the "no need", "border line" and "definite" groups included 61.9 %, 29% and 9.1% of students in turn. On the other hand, the same categories in 17 years old students assessed by the dentist were 66%, 30.2% and 3.7% respectively. (p<0.05).
Conclusion: The treatment need based on DHC and AC scores of IOTN did not differ between 12 and 17 years old groups significantly but the demand for orthodontic treatment in "definitive need" category was more in 12 years old group.