Abstract
This study was initiated to investigate the in vivo changes of pit and fissure sealant over a long term.
In order to investigate the detailed changes of the relationship of sealant to the occlusal surface in the mouth, it is essential to locate the same point on the the series resin replicas which are taken from the succesive examinations. The technique to standardize the three-dimensional position of the resin replica was innovated and reported on in this article.
By utilizing the function of the optic microscope to measure the focus depth, the three points which are located on the occlusal surface and are considered not to be worn down by mustication, were so rotated that these points composed the same horizontal plane. These three points were always selected for the succesive samples, and were fixed accurately enough to observe the same area of observation.
The consecutive samples of the resin replicas taken from the same tooth, always standardized by this method, were observed by means of the scanning electron microscope and the surface contour analyzer. The latter data composed of the three dimensional coordinates were directly fed into the computer to give the longitudinal contour of the sealant and tooth surface at the same location as was observed by the scanning electron microscope.
As the result, it was indicated that the transitional zone between the sealant and tooth surface was smooth just after the sealant was performed, but at the twelve months later the sealant was abraided, and the discontinuous and concaved step appeared at the transitional zone.
