The Dental cosmos . Having thus protected itself from the irritating agent, it deposits fromthat time on ivory of a nearly or quite normal structure. Cases ofthis class are represented in Figs. 26-28. In Fig. 26 an iron ball 5H THE DENTAL COSMOS. passed through the thin wall diagonally at c, remaining lodged inits present position ; the wound is closed from without by cementum,while the pulp has inclosed the ball in osteo-dentine (except at e,where a small abscess seems to have formed), and was at last engagedin rapidly piling up ivory at d, to completely separate itself from theball. In Fig.
The Dental cosmos . Having thus protected itself from the irritating agent, it deposits fromthat time on ivory of a nearly or quite normal structure. Cases ofthis class are represented in Figs. 26-28. In Fig. 26 an iron ball 5H THE DENTAL COSMOS. passed through the thin wall diagonally at c, remaining lodged inits present position ; the wound is closed from without by cementum,while the pulp has inclosed the ball in osteo-dentine (except at e,where a small abscess seems to have formed), and was at last engagedin rapidly piling up ivory at d, to completely separate itself from theball. In Fig. 27 a leaden ball penetrates the tusk at a, and remainslodged in the wall, becoming itself completely torn out of shape bythe resistance of the ivory. Here, again, the microscopical examina-tion shows the wound to be closed from without by cement ; the frag-ments of lead are most perfectly enveloped in osteo-dentine by thepulp, which, having completely protected itself, is now depositingregular ivory at b b. Fig. 1 Fig. 28.—Part of a section of a tusk with two iron balls in situ, a, entrance of balls ; d, wallof irregular dentine being thrown up over ball c. Fig. 28 represents the very interesting case in which two ironballs are found lying side by side. I have seen in all four cases ofthis kind, but the one here illustrated is the only one showing theentrance and course of the balls. We must suppose that in suchcases both balls were propelled together from the same barrel. In thepresent case, one of them, b, was evidently made by bending or ham-mering a nail together. Having broken through the wall of the tooth at a, they remainedadhering to the inner surface, and the pulp had at the time the tuskwas taken already begun, at d, to build up a wall around the ball e,which in course of time would have completely encapsuled it orbrought it into the solid dentine. In this case, again, the outer por-tion of the track is filled in with cement, the inner portion with moreor less
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectdentist, bookyear1890
