Objective: To investigate the potential use of two-dimensional digital images as an alternative to orthodontic casts in the assessment of malocclusion and orthodontic treatment need.
Material and methods: Assessment of malocclusion (Angle's classification of molars, overjet, and overbite) and orthodontic treatment need (Index of Orthodontic Treatment Need (IOTN): Dental Health Component (DHC) and Aesthetic Component (AC)) was conducted on 313 study casts and their images by two trained and calibrated examiners. Agreement of orthodontic treatment need and Angle's molar classification was assessed employing Kappa statistics (kappa). Agreement of overjet and overbite (measured in mm) was assessed in comparison and correlation analyses. Inter- and intra-examiner reliability of assessment was investigated.
Results: There was substantial agreement of the molar relationship classifications (kappa >0.70), orthodontic treatment need as assessed by IOTN-DHC (kappa =0.79) and IOTN-AC (kappa =0.56) between measurements obtained from orthodontic casts and their images. There was also substantial agreement of measurements of overjet and overbite as obtained from orthodontic casts and their images. The standardized directional differences of overjet and overbite were <or=0.2. The intra-class correlation coefficients of assessments of overjet and overbite obtained from orthodontic casts and their images were >0.90. Inter- and intra-examiner reliability for the assessment of malocclusion and orthodontic treatment need was acceptable.
Conclusion: Two-dimensional digital images can be used as an alternative to casts in assessment of malocclusion and orthodontic treatment need.