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Three-dimensional photographs for determining the Index of Orthodontic Treatment Need in scientific studies
Lea Kragt1, Ad M Hermus2, Eppo B Wolvius3
1Postgraduate student, Department of Oral and Maxillofacial Surgery, Special Dental Care and Orthodontics, Erasmus Medical Centre, Rotterdam, The Netherlands; The Generation R Study Group, Erasmus University Medical Centre, Rotterdam, The Netherlands.
Introduction:
Plaster casts as the medium for data collection in orthodontic studies pose disadvantages. In this study, we aimed to assess the validity and reliability of using 3-dimensional (3D) photographs instead of plaster casts to determine the Index of Orthodontic Treatment Need (IOTN) score.
Methods:
Data were collected retrospectively from the clinical records of 91 subjects. The IOTN grades were independently determined first from plaster casts, then from 2-dimensional (2D) and 3D photographs only, and then from 2D and 3D photographs combined with radiographs. IOTN grade agreement was assessed using kappa statistics and percentages of agreement.
Results:
The percentages of agreement between both photographic sets and the plaster casts varied among the different occlusal traits from 63.7% to 93.4%. Agreement between the IOTN grades obtained from 2D and 3D photographs only and the IOTN grades obtained from plaster casts was fair (K = 0.35). The reliability of using 2D and 3D photographs instead of plaster casts was improved when those were combined with radiographs.
Conclusions:
In general terms, orthodontic treatment need can be assessed from 2D and 3D pictures; however, the individual occlusal traits are sufficiently assessed only when these pictures are combined with radiographs. Plaster casts remain the preferred method compared with 3D pictures for assessment of the IOTN.
