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In microscopy, negative staining is an established method, often used in diagnostic microscopy, for contrasting a thin specimen with an optically opaque fluid. In this technique, the background is stained, leaving the actual specimen untouched, and thus visible. This contrasts with positive staining, in which the actual specimen is stained.
Rubber cups, also called prophy cups, are used in the hand-piece. Polishing paste, prophylactic paste, usually containing fluoride, is used with the rubber cups for polishing. Rubber cups should not be used over the cementum area as it may remove a layer of cementum at the cervical area. There are two popular types of prophy cups: 4 webs and 6 ...
The negatively charged cell wall of many microorganisms attracts the positively charged chromophore which causes the specimen to absorb the stain giving it the color of the stain being used. Positive staining is more commonly used than negative staining in microbiology. The different types of positive staining are listed below. [1]
Failure to completely clean out the necrotic soft tissue of the pulp system may cause staining, and certain root canal materials (e.g., gutta percha and root canal sealer cements) can also. [1] Another possible factor is the lack of pulp pressure in dentinal tubules once the pulp is removed, leading to incorporation of dietary stains in dentin. [1]
Negative staining Adsorption onto tissue or the surface of viruses and its electron density are the bases of phosphotungstic acids action as a negative stain. This electron density arises from the presence of the 12 tungsten atoms which each have an atomic number of 74. The mechanism of the adsorption onto tissue has been proposed as being ...
Dental radiographs, commonly known as X-rays, are radiographs used to diagnose hidden dental structures, malignant or benign masses, bone loss, and cavities.. A radiographic image is formed by a controlled burst of X-ray radiation which penetrates oral structures at different levels, depending on varying anatomical densities, before striking the film or sensor.
[1] More sophisticated varieties of plaque disclosing agents contain several dyes, which selectively stain plaque of different ages. With the most common variety, immature plaque stains red, mature purple, and pathological acidic plaque blue. This is owing to the blue dye washing off immature plaque, and acid degrading the red dye.
Impression paste is traditionally used to take the working (secondary) impressions for a complete denture. When used with a special tray it requires 1 mm of spacing to allow for enough thickness of the material; this is also termed a close fitting special tray. [2] It is available as a two-paste system: Base paste: zinc oxide; Catalyst paste ...