Validity of using intraoral photographs in assessing orthodontic treatment need

Objectives: State Medicaid programs use different occlusal indices to determine orthodontic eligibility, with some states making these decisions based exclusively on intra-oral photographs. However, no studies have examined the validity of using intraoral photographs in assessing orthodontic treatment need. The objective of this study is to determine the validity of using intraoral photographs compared to plaster models for assessing orthodontic treatment need and determining eligibility for publicly funded orthodontic coverage. Methods: Orthodontic measurements of occlusal indices [Peer Assessment Rating (PAR), Handicapping Labiolingual Deviation (HLD), Salzmann, Modified Treatment Priority Index, Discrepancy Index, and Index of Orthodontic Treatment Need (IOTN)] were measured by one examiner on both intraoral photographs and plaster models of 154 Orthodontic patients. The study sample was stratified based on malocclusion severity using PAR index score: mild (< 17), moderate (17< PAR <= 39), and severe (> 39). Results: The sample mean age was 20.2±10.67 years, with 54% representing class I, 26% class II, and 20% class III malocclusion. The Intra Class Correlation Coefficient between the scores of the different indices was above 0.91, which demonstrates excellent agreement between plaster models and intraoral photographs. All indices, except for Salzman, demonstrated almost perfect agreement (kappa statistic greater than 0.8) between plaster models and intraoral photographs in their ability to determine Medicaid eligibility for orthodontic coverage. No statistically significant differences were found in determining eligibility between casts and photographs after adjusting for PAR severity and index used (P= 0.37). Conclusions: Intraoral photographs are valid for assessing orthodontic treatment need only, but further investigation of inter-examiner reliability is needed.