The etiology of osseous deformities of the head, face, jaws and teeth . is l^rought to bear on the anterior alve-olar arch is very unequal, certain modifications occur. Anunequal pressure exerted by the cuspids in their eruption will THE HEAD, FACE, JAWS AND TEETH 435 force one side of the arch farther forward than the the first molar on one side has been extracted, whilethat on the other side remains, the forward movement isnecessarily one-sided, and a corresponding irregularity fol-lows. The tardy extraction of temporory teeth goes far inforcing the germs of the permanent teeth ou
The etiology of osseous deformities of the head, face, jaws and teeth . is l^rought to bear on the anterior alve-olar arch is very unequal, certain modifications occur. Anunequal pressure exerted by the cuspids in their eruption will THE HEAD, FACE, JAWS AND TEETH 435 force one side of the arch farther forward than the the first molar on one side has been extracted, whilethat on the other side remains, the forward movement isnecessarily one-sided, and a corresponding irregularity fol-lows. The tardy extraction of temporory teeth goes far inforcing the germs of the permanent teeth out of place. Irregu-larity in the lower incisors through faulty occlusion modifiesgreatly the direction of the upper teeth. Sometimes centrals projecting in a line in front of thelaterals are met with. (Fig. 178.) In this case the centralserupted properly; but the arch being undeveloped, there isnot room for the laterals. These are carried forward by theposterior column and in by the cuspids, and are possiblydriven in by the lower incisors, which, instead of striking. Fig. 180. within them, strike without, exaggerating the this is not the case, and the laterals strike outside of thelower teeth, the upper arch is too large for the lower, and theupper centrals, not finding the proper support below, areforced out in a similar manner, A similar condition is that in which the central incisorsstrike within the laterals. (Fig. 179.) The cause is the same;but the laterals in erupting fail to find the proper supportand project outward, while the centrals occlude properly. Inthis case the upper maxillary arch is not necessarily too largefor the lower; but the teeth are crowded. One form of irregularity that is occasionally met withis that which gives rise to a right angle in the region of thecuspids, the incisors being in a straight line. (Fig. ISO.)There are, of course, cases of this kind where the upper and 436 ETiOLOcr of osseous deformities of lower arches resemble eac
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Keywords: ., bo, bookcentury1800, bookdecade1890, booksubjecthead, bookyear1894
