Image distortion of intra-oral photographs: The root coverage model.

Aim: Clinical photographs have been advocated in studies dealing with the quantity of root coverage. Changes in different angles of the camera when taking a photograph may lead to parallax errors resulting in inaccurate measurements. The aim of this study was to explore the distortion of the photographs according to the shooting angle.
Methods: A dental simulation model with a recession defect on tooth 21 was used. Photographs were taken with a digital camera at 5° intervals between 0° to 35°, by shifting the position of the model. Recession depth and root surface area were calculated with ImageJ and implemented in a mathematical model. The relationship between the experimental measurements and the outcomes of the mathematical model was statistically evaluated. The model was confirmed by clinical data.
Results: When the central axis of the lens of the camera focused on the experimental tooth is within a cone angle ≤36°, the maximum distortion of the recession area ranges from 0% to 14%, the maximum percentage occurring when the angle is coronal to the central axis.
Conclusions: Photographs without an external device connected to the camera provide a valuable support for root coverage assessment when using ImageJ as a measuring tool.
(© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)