THE RELATION OF THE INNER BORDER OF BACTERIAL FILM ON THE TOOTH WITHIN THE GlNGIVAL CREVICE TO THE ZONE OF DISINTEGRATING EPITHELIAL ATTACHMENT CUTICLE CHARLES C. BASS, M.D. New Orleans, La.
From the School of Medicine, Tulane University of Louisiana.
Vol. 2, No. 12, Pages 1580·1590, December, 1949
Studies promoted by facilities to which the author has had access at the School of Medicine, Tulane University of Louisiana, and by aid for equipment and supplies provided by the University.
The zone of disintegrating epithelial attachment cuticle (zdeac) is a useful landmark which can be demonstrated on extracted tooth specimens by appropriate technique. It accurately indicates the location, before the tooth was extracted, of the outer border of the epithelial attachment. As the location of the epithelial attachment moves apexward in the course of the disease process, periodontoclasia, the location of this demonstrable line (the zdeac) changes correspondingly apexward from its normal location high on the anatomical crown.2
This line consists of a narrow band of variable width, of epithelial attachment cuticle, from which the cells of the epithelial attachment have been removed or destroyed.1 This strip of epithelial attachment cuticle which is not covered and therefore is not protected by epithelium is thus exposed to the encroachment of the bacterial film adhering to the surface of the tooth within the gingival crevice. It is also exposed to the effect of the microflora inhabiting the narrow space existing between the more or less permanent or constant film attached to the tooth and the inflamed gingival side of the crevice (sulcus or pyorrhea pocket). To what extent the disintegration of this exposed (not protected by epithelial cells) strip or zone of epithelial attachment cuticle is caused by the attached bacterial film, or by the microflora of the space (crevice) between the film and the crevicular epithelial surface, is not known at the present time. Probably it is a very complex process influenced to variable extent by both the attached bacterial film and the free (not attached) flora sandwiched in between the film and the crevicular epithelium, The purpose of this paper is to direct attention to the constant close relation of the inner border of the attached film pad on the tooth to the zdeac.
Material and Methods
Extracted tooth specimens preserved in formalin (preferably 2.5 per cent following the original fixation in any strength from 2.5 per cent to 10 percent) are satisfactory. Specimens should not be scraped, scrubbed, washed, or allowed to dry before fixation. On most specimens one can usually find areas where more or less receding of the outer border of the epithelial attachment and corresponding receding of the zdeac has occurred. On many specimens the receding is already well advanced. Specimens from adults arc usually more satisfactory for the present purpose. In general the zdeac is located farther toward the apex on specimens from older than from younger subjects. The equipment and technical methods previously described for demonstrating the zdeac are necessary for the present purpose. In addition to the 0.35 mm. micrurgic blade previously suggested for removing and manipulating small pieces of cuticle and other material, a similar chisel- or spatula-shaped blade, not more than 0.15 to 0.20 mm. wide, is needed for accurately picking very small particles of material from the inner border of the bacterial film. The tooth specimen is stained for about one minute in crystal violet solution (0.5 per cent in water) and then gently washed in water. It is now ready for examination under the dissecting microscope. Good incident lighting is necessary.
On favorable specimens the purple-stained zdeac can be recognized satisfactorily at some place or places on the specimen. Often it can be traced all the way around the tooth. Usually there is more or less distortion, at places, of the soft material on the tooth, produced by the manipulations of extraction. Both the zdeac and the bacterial film may have been disturbed or scraped away at any particular location, and this must be kept in mind in interpreting conditions found there. However, it is usually possible to find locations on most specimens at which neither the zdeac nor the inner border of the bacterial film has been disturbed.
The disintegration (breaking up) has progressed for a longer period of time at the outer border of the zdeac than at the deeper apexward border.
Therefore, it is more advanced on that side of the zone. Loose or partially detached pieces of cuticle can be found there. Debris from the disintegrating cuticle and the irregular outline (Fig. 1), resulting from breaking off of loosened particles, makes it difficult to identify accurately the exact outer border of the zone at a given place. Moreover, the usual slight to considerable extension of the inner border of the bacterial film over the outer border of the zone tends to obscure it.