On the structure and mode of formation of the dental tissues, according to the principle of "molecular coalescence" / by George Rainey.

  • Rainey, G. (George), 1801-1884.
Date:
[between 1800 and 1899?]
Catalogue details

Licence: Public Domain Mark

Credit: On the structure and mode of formation of the dental tissues, according to the principle of "molecular coalescence" / by George Rainey. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

    12/44 (page 10)
    join to form continuous wavy lines. These lines, after getting more defined and sharper, coalesce into the ordinary forms of enamel, in which all appearance of the antecedent stages be- comes more or less completely effaced, or, in some cases, totally o])literated. The verification of these facts can be easily made by a careful examination of the cusps of the foetal calf in the earliest stages of calcification; and for this purpose the portion of cusp examined should be split longitudinally into two equal pieces, one presenting the enamel and the other the dentine surface to the observer, so that they may be seen together side by side. Several cusps should be split up for this pur- pose, and the examination will be facilitated by the employ- ment of glycerine.* It is scarcely necessary to say that this examination requires good illumination and great nicety of adjustment. At the commencement itwill be made more easily by tracing the film of enamel backwards from the point of the cusp towards the edge of the matrix. The matrix receiving the enamel particles can generally be seen for some distance, but it gradually disappears, becoming blended with and concealed by the contiguous layers of enamel. The films of newly formed enamel soon show a disposition to break up into irregularly quadrilateral forms; but in no instance have I met with re- gular hexagons, as described by some authors. The laminated character of dentine and enamel will, from the explanation just given of their mode of formation, admit of being easily accounted for; the degree of its distinctness depending upon the completeness or incompleteness of the coalescence of the dentine and enamel particles, will vary in different teeth. Some occasional appearances also, such as very distinct inter- globular spaces about the extremities of the laminae; and the lines called contour lines or markings, will be explicable on the same principle; as well as the homogeneous form of enamel found in some animals, and the absence of any appre- ciable spaces in some parts of all teeth, the dentine being in these parts said to have no tubules, as before noticed. The next dental tissue is the osteo-dentine or crusta petrosa. The mode of formation of this stnicture can be beautifully seen in the molar teeth of the foetal calf at the free margin of the pulp-cavity, where a thin scale of this sub- * I have not liad an opportunity of judging whether these would preserve their natural appearanee it' kept in giycernie for iiianv months. But I may observe that I iiad a piece of oyster-shell which showed beautifully the coalescing carbonate of lime by polarized light; of wliich I put one piece into Canada balsam, and the other into thick glycerine—the former remains now as when first put uji, but the latter, after some months, began to lose its natural appearance, and now the large globules of carbonate have altogether disappeared.