Periodontal pocket clearance by gamma scintigraphy in human volunteers

With the interest in the delivery of drugs to the periodontal pocket has come an increased need to determine the loss of formulations from the site of application. In this respect, gamma scintigraphy has been used to measure formulation clearance in mucosal sites such as the oesophagus, nose and eyes by assessing the persistence of an incorporated radiolabel. However, the technique has not been used to follow clearance from the periodontal pocket.

The aim of this study was therefore to assess the potential of gamma scintigraphy to follow the loss of 2 contrasting formulations. 10% chitosan gel and normal saline.

Technitium-99m was used as the radionuclide and was incorporated into the formulations on the day of use. 9 subjects contributed up to 2 pockets for each formulation with probing depths > or = 5 mm.

The results demonstrated that gamma scintigraphy was able to follow the loss of the radiolabel despite the small volumes of formulation placed in situ. The mean (SD) times (min) for the original counts to decline to 10%, 50% and 90% of the original values were: T10: chitosan 74.5 (59.0), saline 40.3 (21.1), T50: chitosan 41.5 (34.1) saline 20.8 (11.7) and T90: chitosan 8.5 (10.8), saline 1.4 (3.7) respectively. Clearance times of the 2 formulations were significantly different from each other (p<0.05).

In conclusion, gamma scintigraphy is a sensitive method for assessing clearance from the periodontal pocket, and further studies are merited to optimise the use of the technique.