Measurement methods
In this study, a digital camera was used capture images of gingival papilla of each patient. The pictures were taken at different time points during treatment. Camera should be parallel to the occlusal plane, and be pointed in a perpendicular angle to gingival papilla and cervical 1/2 of the buccal surface of teeth. Every picture should follow this protocol. All pictures were imported in a computer for detailed measurement, which is more recognizable and convenient, and can be measured repeatedly. It is believed that the error caused by photo shooting can be massively reduced by strictly following the protocol. Priest et al. 