The Dental cosmos . e Deposition of Osteoblasts. The osseous portion of the upper maxilla in these cases is not exces-sively developed. The facial angle is less than normal, as the alveolarprocess and teeth protrude. The lower maxilla may be normal or thechin may recede. The partial eruption of the first molars makes thebite too close in these cases. Notwithstanding this, when the palatalsurfaces of the upper central incisors are normal in outline, the lowerincisors are prevented from sliding back against the palate by comingin contact with the basilar surfaces ; but when these surfaces are no
The Dental cosmos . e Deposition of Osteoblasts. The osseous portion of the upper maxilla in these cases is not exces-sively developed. The facial angle is less than normal, as the alveolarprocess and teeth protrude. The lower maxilla may be normal or thechin may recede. The partial eruption of the first molars makes thebite too close in these cases. Notwithstanding this, when the palatalsurfaces of the upper central incisors are normal in outline, the lowerincisors are prevented from sliding back against the palate by comingin contact with the basilar surfaces ; but when these surfaces are notsufficiently curved, the lower incisors have a tendency to glide back-ward toward the palate and finally find a resting-place in the alveolarprocess. The irritation which results from the pressure against themucous membrane produces excessive deposit of bone-cells in theinner plate of the alveolar process, which causes the superior centralincisors to be carried forward. This irritation is intensified by the Fig. masticating process, and the incisors, being deprived of their naturalfunction, flare out. As the central incisors begin to protrude, thelaterals also become affected, and finally the cuspids. The cutting-edges of the teeth appear below the upper lip, and the lower lip iscaught beneath, increasing the tendency to stand out. The more theorbicularis oris is deprived of its function, the greater the tendency ofthe upper teeth to project. The marked influence of the upper lip inkeeping the teeth in position is shown in the case of the upper incisors,that turn inward in excessively developed upper maxillae. Fromwant of proper occlusion, the lower alveolar process becomes abnor-mally developed as the teeth are carried up against it. io8 THE DENTAL COSMOS. The extent of the anterior movement depends upon the height ofthe vault, as a high vault permits a greater arc of upward movementof the lower incisors than a flat roof. When the second molars erupt, they are prevented f
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