Aim: Awareness of orthodontic treatment need is very important in hygienic planning and dentistry insurance. This study determined the rate of orthodontic treatment need based on IOTN index in 12-16 year old patients undergoing orthodontic treatment in 4 Tehran dental schools and 2 orthodontic private offices in 2004-2006.
Materials and Methods: In this descriptive research, study casts and charts for 209 patients aging 12-16 in 4 dental schools of Tehran and 2 orthodontic private offices were surveyed based on IOTN index in different ages and in terms of gender. Classifications (CI,II,III), overjet, openbite, deepbite, crossbite, contact displacement, supernumerary, ankylosed, impacted and missing teeth, cleft lip, cleft palate and lip, cleft palate, and facial asymmetry were evaluated, and compared with IOTN results achieved from 22, educational districts of Tehran. Chi-square, Fisher's Exact and ratio equality tests were used to analyze the data.
Results: Among 209 patients under treatment, 22.5% needed very severe treatment (grade5), 33% severe(grade4), 4.36% average (grade3) and 8.2% needed less or no treatment (grades1&2). The number of girls being treated was more than boys (66.5%); most of the patients under treatment were 12 years old (67 persons= 32.1%); the most common causes of orthodontic treatment were contact displacement 57.4%, overjet 22.5 and deepbite 17.7%.
Conclusion: Regarding treatment need among patients under treatment, we concluded that most of the treated patients needed treatment based on IOTN and the number of patients needing simple treatment was very small, so treatment decisions were made according to IOTN.