Abstract
The purpose of this study is to clarify the cause of the discoloration of gingiva by silver alloy powder. Sixty-four healthy rats were used in this study. With No. 1/2 round bur for the dental engine, standardized small cavity was prepared at the mesiolingual cervical portion of the upper molar. Silver alloy powder had been inserted into the small cavity of the maxillary left side of each rat, whereas the right side was used as control. Post operative changes in process of time in the gingival tissue were studied macroscopically, histopathologically and by means of analytical electron microscope (AEM).
The results were as follows;
1. Under the light microscope, many dark depositions (metal) were observed in the lamina propria of the attached gingiva. These dark depositions had been taken into the histocyte like cells and the multinucleate giant cells. Many small depositions were sporadically present around those histocyte like cells and the multinucleate giant cells.
2. Under the electron microscope, the dark depositions (metal) had been taken into the multinucleate giant cells. These cells had long cytoplasmic processes and they had pseudopodia in their membrane of opposite site of the dark depositions and many vacuoles in the cell. These had many lysosomes, vacuoles, endocytosed materials in vacuoles and Golgi's apparatus. The presence of dense concretions were shown to be the complexes of needle-like components and electron-dense materials. The needle-like components were usually organized into concentric lamellae, on which the dense materials deposited.
3. By AEM, it was determined that the elements Ag, Zn and Sn were present in the dark depositions (metal). The element of the concretions was Ag, which was considered to be the form of Ag2S.
4. It was confirmed by this experimental study that the concretions were an essential factor in the discoloration of gingiva by the silver alloy powder, and the concretions were shown the form of the small dense granules as the result of the dissolution of the silver alloy powder.
