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P. 788
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786 ORTHODONTIA AS AN OPERATIVE PROCEDURE.
tween them, as .shown in Fig. 741, thus forcing them outward till thcv
are in proper alignnu'nt.
In case of a semi-saddle-shaped arch (Figs. 609 and 610)—that is,
one in which the irregularity is confined to one side—three or more
teeth on the opposite side should be groujied together for anchorage.
If the case is an aggravated one wiiich will not admit of expansion,
extraction must be resorted to—selecting, of course, the tooth or teeth
most out of line.
Class 13. Lack of Anterior Occlusion. Etiology.—This irregu-
larity is generally of constitutional origin, and may be due
(a) To lack of development of the ramus of the lower maxilla.
(See Fig. 800.)
(6) To lack of development of the anterior portion, or
(c) To hypertrophy of the posterior portion of the alveolar process.
id) It may be acquired by thumb-sucking, as shown in Fig. 801.
The jaws being held apart thus pre-
Fig. 800.
vents normal eruption of the anterior
teeth and consequent development of
Fig. SOI.
Lack of anterior occlusion (Talbot). Lack of anterior occlusion caused by thumb-
sucking (Talbot).
the anterior portion of the alveolar ridge, or allows excessive develop-
ment of the posterior portions.
{e) It may be acquired from the habit of mouth-breathing, which,
relieving the molars from pressure, permits abnormal development of
the alveolar process containing them. A case recently occurred in
the writer's practice which illustrates this. The patient was fifteen
years of age, and was a mouth-breather. There Avas a space of an
eighth (jf an inch between the cutting edges of the upper and lower
incisors, wdiile three or four years before she could bite off a thread
with these same incisors.
That the opening w^as not caused solely by the eruption of the
second molars was shown by the fact that the first molars occluded
equally well. The case was reduced by grinding the molars till the
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786 ORTHODONTIA AS AN OPERATIVE PROCEDURE.
tween them, as .shown in Fig. 741, thus forcing them outward till thcv
are in proper alignnu'nt.
In case of a semi-saddle-shaped arch (Figs. 609 and 610)—that is,
one in which the irregularity is confined to one side—three or more
teeth on the opposite side should be groujied together for anchorage.
If the case is an aggravated one wiiich will not admit of expansion,
extraction must be resorted to—selecting, of course, the tooth or teeth
most out of line.
Class 13. Lack of Anterior Occlusion. Etiology.—This irregu-
larity is generally of constitutional origin, and may be due
(a) To lack of development of the ramus of the lower maxilla.
(See Fig. 800.)
(6) To lack of development of the anterior portion, or
(c) To hypertrophy of the posterior portion of the alveolar process.
id) It may be acquired by thumb-sucking, as shown in Fig. 801.
The jaws being held apart thus pre-
Fig. 800.
vents normal eruption of the anterior
teeth and consequent development of
Fig. SOI.
Lack of anterior occlusion (Talbot). Lack of anterior occlusion caused by thumb-
sucking (Talbot).
the anterior portion of the alveolar ridge, or allows excessive develop-
ment of the posterior portions.
{e) It may be acquired from the habit of mouth-breathing, which,
relieving the molars from pressure, permits abnormal development of
the alveolar process containing them. A case recently occurred in
the writer's practice which illustrates this. The patient was fifteen
years of age, and was a mouth-breather. There Avas a space of an
eighth (jf an inch between the cutting edges of the upper and lower
incisors, wdiile three or four years before she could bite off a thread
with these same incisors.
That the opening w^as not caused solely by the eruption of the
second molars was shown by the fact that the first molars occluded
equally well. The case was reduced by grinding the molars till the
