. A text-book in general physiology and anatomy. Physiology, Comparative; Anatomy. STEUOTURE OF THE TEETH 97 animals. For example, in the rabbit the dental formula is as follows: TJ UU-+J + !<â 1 2 + 2,0 + 0,3++3 ^^ Rabbitdentalformula = ^ + {^q + 0^2 + 2,3 + 3 = ^^' Structure of the teeth.â(See Fig. 27.) The part of a tooth above the gum is called its crovm- When a tooth is pulled we find that the crown is only a small part of the entire tooth. At the point where it enters the gum it narrows into a part called the neck and extends below in one or more projections called the jangs or roo
. A text-book in general physiology and anatomy. Physiology, Comparative; Anatomy. STEUOTURE OF THE TEETH 97 animals. For example, in the rabbit the dental formula is as follows: TJ UU-+J + !<â 1 2 + 2,0 + 0,3++3 ^^ Rabbitdentalformula = ^ + {^q + 0^2 + 2,3 + 3 = ^^' Structure of the teeth.â(See Fig. 27.) The part of a tooth above the gum is called its crovm- When a tooth is pulled we find that the crown is only a small part of the entire tooth. At the point where it enters the gum it narrows into a part called the neck and extends below in one or more projections called the jangs or roots which anchor it firmly in its bony socket. The incisors and canines have only one fang, the bicuspids may have two, while the molars may have as many as five and as few as two. The internal structure of all human teeth is practically the same. If we split a tooth in two, lengthwise, examina- tion shows that the crown is covered with an external layer of hard matter called enamel. This thins down at the neck and is succeeded by a fang covering called cement. The main bulk of the tooth is formed of a bonelike sub- stance called dentine which surrounds a small central cavity called the pulp cavity. During life this cavity is filled with nerve fiber and blood vessels interlaced in a network of connective tissue, called the pulp. It is lined with a layer of epithelial cells which secrete the mineral matter of which the outer layers are formed. This cavity has a small ZDDY. PHYS. â7. Fig. 27 â Section of a tooth; k, crown; e, enamel; », neck; f/, dentine; /, fangs; e, cement; p, puip cavity inclosed l)y Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Eddy, Walter Hollis, b. 1877. New York, Cincinnati [etc. ] American book Co
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