Observations from shadowed collodion replicas of teeth with amalgam restorations.

T HE USE of conventional or increased handpiece operating speeds for the shaping of cavities in human teeth results in vibration, temperature changes, and other physical factors within the calcified tooth tissue and its organic matrix. The airbrasive and ultrasonic methods of cutting tooth tissue appear to create similar forces. The effects of these trauma may or may not be significant to the longevity of the healthy functional tooth; this may depend somewhat on the severity of the forces involved. The ultimate goal of this project is the study of the traumatic effects on both hard and soft tooth tissue which might develop when dental instruments are operated under various conditions. Although the actual development of observable changes in tooth tissue due to rotating instruments is conjecture, it seems likely that some alteration of the normal histologic pattern could occur. Extracted teeth containing amalgam restorations were selected for study by the shadowed collodion replica technic in order, first, to establish a method of preparation which would allow rapid and accurate examination by the optical microscope, and second, to survey these specimens for any changes from normal which may have occurred. Shadow-casting for optical microscopy, using collodion as the substrate and aluminum as the metallic film,25 and the general suggestions of Scott and Wyckoff13' 14 for replica preparation were used as a basis for the development of the technic. This paper presents in some detail a technic for preparing shadowed collodion replica specimens of sectioned teeth containing restorations, for the general examination of the hard tooth tissue with the optical microscope. Some observations of both normal and affected tooth tissue are presented.