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The loss of the deciduous molars is a frequent cause of malocclusion.
Behind the temporary teeth erupt the six-year-old
molars which have been described as "the key teeth of occlusion."
Early extraction of the temporary molars allows these permanent
teeth to "drift" too far forward, causing general overcrowding.
Prolonged retention of deciduous teeth can also produce abnormality.
These teeth, when in a septic condition, remain as
foreign bodies and deflect the erupting tooth. That is why
inspection and treatment of children's teeth is essential, so as
to avoid these unfortunate sequelae.
Mouth breathing caused by nasal obstruction such as adenoids
and hypertrophied tonsils frequently produces high dental arches,
with a general overcrowding of the teeth. All cases of dental
deformity due to nasal Obstruction should have surgical attention
before dental treatment is commenced. During mouth breathing
the mouth is continually open, and tension of the cheek muscles
produces pressure on the plastic bones, causing contraction of the
arches. When the mouth is closed during normal breathing the
tongue exerts pressure against the palate, and this pressure prevents
narrowing of the arches, but in the mouthbreather that
action of the tongue is lost, and with it the natural stimulation of
the development of the jaws.
Frequent action of the tongue is necessary for proper formation
of the jaws. There is something to be said for the " chatterbox,"
and mothers of garrulous children may console themselves
with the fact that frequent exercise of the child's tongue is invaluable
in producing well-formed arches.
Bad habits during babyhood must be corrected, such as
sucking a "dummy," the thumb, toe or lip, as they push the
soft baby bones out of shape. Unfortunately, many parents
readily condone such habits, presumably in the hope of keeping
the child quiet, but in permitting these habits they seem unaware
of the danger of producing malformation of the jaws and subsequent
irregularity of the teeth. Better development of the arches
could be achieved if mothers would realise that proper function
of the child's teeth can only be obtained by giving food which
requires thorough mastication.
It may be remarked that hereditary influences are often
responsible for some cases of irregularity and malformation of the
jaws.