The etiology of osseous deformities of the head, face, jaws and teeth . achother; occasionally they do not develop their full length. Ineither case the lower incisors strike against the mucous mem-brane of the roof of the mouth, which constant irritationstimulates the deposition of the bone-cells in the process, as ifnature would defend it against the abnormal pressure of thelower teeth. Were the occlusion correct, the constant pressure 468 ETIOLOGY OF OSSEOUS DEFORMITIES on the roots of the teeth would doubtless, in part, counter-balance the excessive deposit by waste. As it is, the roots oft
The etiology of osseous deformities of the head, face, jaws and teeth . achother; occasionally they do not develop their full length. Ineither case the lower incisors strike against the mucous mem-brane of the roof of the mouth, which constant irritationstimulates the deposition of the bone-cells in the process, as ifnature would defend it against the abnormal pressure of thelower teeth. Were the occlusion correct, the constant pressure 468 ETIOLOGY OF OSSEOUS DEFORMITIES on the roots of the teeth would doubtless, in part, counter-balance the excessive deposit by waste. As it is, the roots ofthe upper incisors form an angle with the cutting-edge of thelower teeth, and as the mouth opens and closes, the force ofthe lower incisors is not only spent on the superior process,but also through it on the roots of the upper teeth, forcingthem out more and more. Fig. 217 shows the central incisors have just commenced to move model is from the mouth of a girl eleven years of trouble is extended to the neighboring teeth from the. Fig. 220. nature of the occlusion. Fig. 218 shows the incisors and alve-olar process carried forward by the excessive deposition ofbone-cells. By the action of the lower lip, which cannot closeover the cutting-edges of the upper teeth, but soon getsbetween the superior and inferior incisors, the former arepressed out still more. Fig. 219 shows a side view of thisform of irregularities. Fig. 220 illustrates a remarkablecase of migration of the molars. Want of function encourages a deposit of tartar aroundthe roots of the teeth, inducing Riggs disease later in lifeand loosenino: the teeth. CHAPTER XXXV. SUPERNUMERARY TEETH. Supernumerary teeth are a freak of nature, for which nocause has, as yet, been assigned. It may, of course, be statedthat additional germs were formed during foetal life, but thisis no true explanation, for the question still arises, Whatcaused these ? Plants put forth adventitious buds and show
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