Comparison of different plaque indices with regard to sensitivity and specificity for the quantification of plaque during orthodontic therapy.

To compare four plaque indices used in orthodontics. An objective, quantitative plaque index and three subjective conventional plaque indices were analyzed. The study included n = 50 photographs of n = 50 subjects with a multibracket appliance (MB) in the maxilla and mandible. Photographs were taken using Digital Plaque Imaging Analysis (DPIA) and the Percentage Plaque Index (PPI) was calculated. The conventional plaque indices, a modified version of the Turesky-modification of the Quigley & Hein Index (TQH index), Attin index, and modified bonded bracket index (mBB index) were collected from n = 14 evaluators using the DPIA photographs. The evaluators had different levels of orthodontic experience: n = 4 evaluators had little orthodontic experience, n = 5 evaluators had moderate orthodontic experience, and n = 5 evaluators had a lot of orthodontic experience. Plaque accumulation was assessed differently with the plaque indices. Thus, the plaque indices are not interchangeable. We recommend DPIA as an objective, quantitative and sensitive method for plaque determination in scientific studies. The simple statistical evaluation offers a great advantage over conventional plaque indices.