Page:The American Cyclopædia (1879) Volume VI.djvu/33

 DENTITION DENVER 25 in these sacs are developed the first ten perma- nent teeth of each jaw ; the other six are devel- oped in sacs placed posterior to those of the last milk teeth, which are formed in a manner pre- cisely similar to those of the milk teeth them- selves. The ossification of the permanent teeth commences a little before birth with that of the first molar, and proceeds during the first three years of infancy successively in the incisors, the canines, and the bicuspids. The approach of the time for the eruption of the temporary teeth is announced by an increased secretion of saliva. In the earlier months of infancy the mouth is comparatively dry, but as the teeth shoot into the gums the mouth becomes moist and the child begins to drivel. The progress of dentition is not apparently continuous, but after the erup- tion of each successive pair a pause of one or two months generally follows. The central in- cisors commonly pierce the gum in the course of the 7th month after birth, those of the low- er jaw preceding the upper ones by a short in- terval ; between the 7th and 10th months the lateral incisors make their appearance; from the 12th to the 14th month the anterior mo- lars, and between the 14th and 20th the ca- nines are cut; and the first dentition is com- pleted between the 18th and 36th months by the protrusion of the posterior molars. Both the time and the order of appearance of the first set of teeth admit of a good deal of varia- tion, their progress being hastened or delayed sometimes six or seven months by a lateral in- cisor, or even a molar or canine tooth, cutting the gum before the appearance of the central incisors. The period of primary dentition is at- tended with increased risk to the life of the infant. During its continuance the proportion- ate mortality becomes much increased, and in the bills of mortality numerous deaths are as- cribed to teething alone. It must be remem- bered, however, that at this time all the func- tions of the young being are in a state of great activity, and that teething is but one in a series of changes by which the infant is prepared to substitute for the milk provided by its mother, food suitable to the conditions of its future ex- istence. In a healthy infant dentition in itself is attended with little inconvenience and no danger ; when the teeth come to distend and stretch the mucous membrane lining the gums, there is probably a little tenderness and pain, some fretfulness, and perhaps slight febrile ex- citement ; but in the absence of other causes of disease, this soon passes over. If, however, the nervous system is unduly excitable, denti- tion may seriously complicate other maladies. When the process of dentition is advancing normally, it should never be interfered with ; when the gum is red, swollen, and painful, scarification may be resorted to with advan- tage, and may be repeated if necessary, the trifling loss of blood affording relief to the in- flamed gum. When the tooth is evidently about to pierce the gum, if the child appears to suffer, it may be freed by cutting down to it with the gum lancet. In cases where convul- sions supervene suddenly without an evident cause, if dentition is proceeding actively and the gums are tense and swollen, the gum lan- cet may be resorted to. Occasionally dentition is attended with much fever and derangement of the digestive organs, while a sloughy un- healthy ulceration makes its appearance on the gum over the teeth just about to protrude, or at the edge of the gum of those which have recently been cut. In these cases the gum lancet does positive harm, while they readily yield to a properly regulated diet, and to the use of the chlorate of potash in solution, in doses of one or two grains repeated every four hours. During the earlier period of childhood a bony plate or partition separates the perma- nent from the fangs of the temporary teeth ; as the period approaches in which the former are to replace the latter, this partition disap- pears, and the crown of the enlarged perma- nent tooth makes its way into the cavity of the temporary fang. As the permanent tooth ad- vances, the fang of the milk tooth is absorbed, not however from any pressure exercised by the one upon the other, the two never coming in contact ; and as the crown of the milk tooth falls off, the permanent tooth is ready to re- place it. The first anterior or true molar usually appears at about 6 years ; about the same time or a few months later the central permanent incisors appear ; the lateral ones are developed at 8, the anterior and posterior bi- cuspids at 9 and 10, the canines from 11 to 12, the second true molars from 12 to 13, and the wisdom teeth from 17 to 19. From the inves- tigations of Mr. Edwin Saunders (" The Teeth a Test of Age, considered with reference to the Factory Children "), it would appear that the second dentition furnishes the best physical evidence of the age of children within our reach ; in the majority of instances he found its indications coincided closely with the real age of the children, and when they failed the extreme deviation was but a year. DEBTT01V, a N. E. county of Texas, drained by two forks of Trinity river, and occupied partly by prairies and partly by vast forests called the Cross Timbers ; area 900 sq. m. ; pop. in 1870, 7,251, of whom 500 were col- ored. The chief productions in 1870 were 18,216 bushels of wheat, 173,510 of Indian corn, 41,060 of oats, 11,826 of sweet potatoes, and 674 bales of cotton. There were 6,195 horses, 2,863 milch cows, 85,220 other cattle, 5,331 sheep, and 10,200 swine. Capital, Denton. DENVER, a city of Arapahoe county, Colo- rado, the capital of the county and of the territory, situated on the right bank of the South Platte, at the junction of Cherry creek, 15 m. from the E. base of the Rocky moun- tains, and about 500 in. W. of the Missouri river, 5,267 ft. above the sea; pop. in 1870, 4,759; at the beginning of 1873 estimated by the secretary of the board of trade at