This study aimed to identify predictive factors of having a positive or negatively divergent self-perception from the normative orthodontic treatment need (N-OTN).

All eligible undergraduate students from the School of Dentistry of the XXX were recruited through convenience sampling. They were clinically evaluated to determine their N-OTN using the IOTN and were asked about their self-perceived orthodontic treatment need (S-OTN) using the same scale for both evaluations. The subjects were classified according to the orientation of their perception as: coincident (S-OTN=N-OTN), positive (S-OTN<N-OTN), or negative (S-OTN>N-OTN). Multinomial logistic regression models were implemented to evaluate the contribution of the N-OTN, Angle's malocclusion, oral health-related quality of life (OHRQoL), self-esteem, sex, undergraduate year and age.

Two hundred first- and third-year undergraduate dentistry students were evaluated. It was evidenced that a higher N-OTN increases the probability that S-OTN is positively oriented and decreases the probability that it is negative. A worse OHRQoL score increases the chance that the S-OTN orientation is negative and decreases the chance that it is positive. Moreover, the probability of divergent self-perception in either direction is expected to be lower for women.

Students with a more severe malocclusion tend to have a more positive view of their normative condition. A greater impact on OHRQoL favours having a more negative self-perception of the N-OTN. Women have a less divergent self-perception of the N-OTN.