Treatise on the natural history and diseases of the human teeth : explaining their structure, use, formation, growth, and diseases, in two parts / by John Hunter ; with notes by Thomas Bell.

  • John Hunter
Date:
1839
Catalogue details

Licence: Public Domain Mark

Credit: Treatise on the natural history and diseases of the human teeth : explaining their structure, use, formation, growth, and diseases, in two parts / by John Hunter ; with notes by Thomas Bell. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

    46/127
    tinuations of the enamel, we find processes from the pulp passing down into those interstices as far as the pulp which the tooth is formed from, and there coming into contact with it. After the points of the first-described pulp have begun to ossify, a thin covering of enamel is spread over them, which increases in thickness till some time before the tooth begins to cut the gum. The enamel appears to be secreted from the pulp above described, and perhaps from the capsule which incloses the body of the tooth. That it is from the pulp and capsule seems evident in the horse, ass, ox, sheep, &c, therefore we have little reason to doubt of it in the human species. It is a calcareous earth, probably dissolved in the juices of our body, and thrown out from these parts, which act here as a gland. After it is secreted, the earth is attracted by the bony part of the tooth which is already formed, and upon that surface it crystallizes. The operation is similar to the formation of the shell of the egg, the stone in the kidneys and bladder, and the gall stone. This account for the striated crystallized appearance which the enamel has when broken, and also for the direction of these stria;.* The enamel is thicker at the points and basis than at the neck of the teeth, which may be easily accounted for from its manner of formation; for if we suppose it to be always secreting, and laid equally over the whole surface, as the tooth grows, the first formed will be the thickest; and the neck of the tooth, which is the last- formed part inclosed in this capsule, must have the thinnest coat; and the fang, where the periosteum adheres, and leaves no vacant space, will have none of the enamel. At its first formation it is not very hard ; for by exposing a very young tooth to the air the enamel cracks and looks rough ; but by the time that the teeth cut the gum, the enamel seems to be as hard as ever it is afterwards; so that the air seems to have no effect in hardening it.f * The author has made many experiments on the formation of different calculi, and finds they are formed by crystallization, which were communicated to his brother, and taught by him to his pupils in 1761, and which he proposes to give to the public as soon as his time will permit. f [According to the most accurate observations which I have been able to make, and they are confirmed by those of others, the substance which Hunter terms another pulpy substance, adhering to the inside of the capsule, is nothing more than a thickened and turgid state of the inner layer of the capsule itself, surcharged with blood and probably also with the earthy matter which it is about to deposit, constituting the future enamel-covering of the crown of the tooth. This thickening appears to be somewhat analogous to that extraordinary turgescence which is observable in the mantle of certain species of snail, as our own Helix Pomatia immediately before the calcareous winter operculum is poured out from every part of its surface. The enamel when just deposited is not much more solid than thick cream. It soon sets, but is at first but little coherent, being easily pulverised; it gradu- ally, however, assumes its crystalline form, becomes semitransparent, and ex- tremely hard.]
    digitised image 1
    digitised image 2
    digitised image 3