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774 ORTHODONTIA AS AN OPERATIVE PROCEDURE.

(d) Teeth too large for the jaw and tliercforc projecting forward of
their natural position—indirect heredity.
((') The lower protrusion may be a]ii)arent and not real, owing to
lack of development of the upper maxilla. This may be due to nasal

Fig. 779.

Lower protrusion (Talbot).
obstruction (page 697) or to the injudicious extraction of the first per-
manent molars, as in cases of apparent upper protrusion—acquired.
(/) It may result from the npper oral teeth having erupted back
of their proper position, so as to bite inside of the lower incisors.
Mal-occlusion of incisors.
{g)
Fig. 780.

Excessive development of ramus (Talbot).

Treatment.—If the teeth are too large for the jaw, room may be made
by extraction of the first bicuspids, nnless teeth posterior to them are
selected on account of caries.
The anterior teeth may be moved back by the labial bow shown in