14. Prevention in orthodontics
14.1. Introduction
Orthodontics is a medical field that
specializes in the diagnosis and therapy
of irregularities of the dentition, jaws and
the orofacial system (OFS).
There are a large number
of orthodontic abnormalities. They can be
found in 60-80% of population.
Orthodontic abnormalities have negative
functional and aesthetic consequences such
as:
 functional disorders of dentition
performance,
 altered aesthetics of the dentition
and the OFS, affecting the
physiognomy of an individual,
 abnormalities impair individual’s
oral health by increased tooth
decaying and decreased resistance
of the periodontium,
 complicate prosthetic treatment
of
the
dentition,
impaired
pronunciation
and
decreased
resistance of teeth against injuries.
Logically, the seriousness of irregularities
and time-demanding and expensive
orthodontic treatment make one to focus
on the possibility of prevention
of orthodontic abnormalities.
From a terminology point of view,
terms such as prevention, prophylaxis and
early therapy are often used. Some
therapeutic procedures are directly named
as prophylactic, for example prophylactic
(serial, controlled) extractions.
However, if we want to use the
same terms from other dental medicinal
fields in orthodontics, preventive measures
can also be divided into primary,
secondary and tertiary prevention.
Primary prevention includes the
methods based on detailed knowledge
to prevent the formation of irregularities
and ensure the regular development of the
orofacial system and the dentition. Such
methods represent orthodontic prevention.
Orthodontics also includes effective
measures
to
affect
the irregular
development of the orofacial system and
the dentition in order to prevent further
deterioration of a particular, developing
irregularity. Such measures represent
secondary prevention which is basically
prophylaxis.
All preventive procedures include
early
therapeutic
methods
used
in temporary and early mixed dentition.
Their aim is to prevent the occurrence
of orthodontic irregularities in the
permanent dentition. Such procedures
represent tertiary prevention.
It should be pointed out that
prevention in orthodontics is a specific and
difficult task for the following reasons:
 Abnormalities are not pathological
conditions arising from known
causes and the body has no defence
system against them. Abnormalities
are
developmental
deviations
resulting from great variability
of the OFS, being caused by the
action of various individual internal
and external causal factors.
 The etiology of orthodontic
irregularities is complicated. There
are a lot of etiological factors that
combine, affect each other and are
difficult to identify. In addition,
they may exercise their triggering
effect long before the occurrence
of symptoms of a particular defect.
Abnormalities are not monocausal as they
result from genetic, anatomical, growth,
hormonal, functional and other biological
processes.
The
development
of irregularities is affected by a number
of factors such as the genetic variability
of the size, position, and the number
of teeth, the shape and size of jaws, the
type of the growth of jaws and the OFS
function.
14.2. Causes
irregularities
of
orthodontic
Major causes of orthodontic irregularities:
 Inheritance,
 Factors affecting the intrauterine
development,

Factors affecting
development.
the
postnatal
14.2.1. Inheritance
Inheritance plays a major role in the
development of a large number
of orthodontic irregularities. The study
of inheritance is based on the monitoring
of the occurrence of individual orthodontic
abnormalities
in
homozygous
and heterozygous twins, in particular
populations (population studies) and within
a family (the monitoring of the familial
occurrence of abnormalities, for example,
the study of the mandibular prognathism
of Habsburgs that occurred in the Spanish
branch of the House of Habsburg, having
been recorded for hundreds of years
for many generations in paintings,
engravings and sculptures.
The presence of the prevailing
genetic basis is indicated by the finding
of the same abnormality in siblings,
parents and children or their relatives.
In such a case, it is particularly necessary
to eliminate all factors that could
contribute to the irregular development and
use all means to limit such irregularities.
In spite of expectations that
inherited abnormality will be manifested in
the temporary dentition most significantly,
there are a great number of inherited
irregularities which manifest themselves
in the permanent dentition much later,
for example at puberty. Such an individual
with the inherited genotype who is still
developing will gain characteristic
personal and familial features together with
orthodontic irregularity.
Each individual is a product
of inheritance and external environmental
factors, being unique in a wide range
of normal variations. Within a great
variability of the OFS, inheritance
determines the following features:
 the size and shape of jaws,
 the time and manner of the growth
of jaws,
 the size, shape and the number
of teeth,

the position of tooth buds and the
direction of their eruption,
 a period of the eruption of teeth.
All such features show great variability
and abnormal variants can also be inherited.
Signs can be genetically independent one
of the other, for example small jaw and big
teeth are inherited.
The following particular orthodontic
irregularities are inheritable:
 mandibular prognathism,
 malocclusion,
 some types of distal occlusion (with
the protrusion of upper incisors
or so called pure distal occlusion),
 cleft lip, cleft jaw and cleft palate
with accompanying irregularities
of the dentition,
 abnormal number of teeth –
hypodontia and hyperdontia,
 retention of permanent canines,
 abnormalities in the positioning
of teeth such as diastema and
rotation.
It is assumed that the type of inheritance
during the development of orthodontic
irregularities is polygenic inheritance. The
determination of the feature occurs after
achieving the threshold of effectiveness
of a larger number of small-effect genes.
A combination of inheritance and external
factors also plays an important role –
multifactorial inheritance. Abnormality
occurs when a larger number of particular
genes are acting or when there are more
adverse external factors acting (adverse
external effects may decrease a threshold
value for the development of irregularities).
Here are some examples: inherited cleft
defects,
inherited
hypodontia
with a different degree of missing dental
buds usually accompanied with a tendency
to microdontia (chip-like, small incisors)
and the inheritance of the right crowding of
teeth due to the disproportion between
jaws and teeth.
14.2.2. Factors affecting the intrauterine
development
These factors play a major role in the
development of congenital abnormalities
of jaws and the dentition. Etiogical factors
include:
- teratogenic agents,
- general diseases of the mother
(syphilis, metabolic disorders),
- developmental defects on the basis
of gene mutation, chromosomal
abnormalities or systemic diseases.
14.2.2.1. Teratogenic agents
During the intrauterine development
and growth of the foetus, the foetus can be
affected by substances that may cause
foetal malformations. At low levels,
teratogenic agents will affect the
development of the embryo whereas
at high levels they will have lethal
consequences. The maximum harmful
effect of teratogenic substances is seen in a
period between Day 17 and Day 90 of the
foetal development.
Teratogenic substances that affect
the development of dentofacial structures
include:
 chemical substances (including
pharmaceuticals),
 infectious agents,
 other factors such as nicotinism,
chronic
ethanol
intoxication,
physical factors (X-ray radiation,
radioactivity), stress, qualitative
and quantitative changes in a diet,
geographical factors.
Pharmaceuticals to be avoided during
pregnancy
include
the
following
substances:
The following substances are
contraindicated during pregnancy because
of the potential risk of foetal and
embryonic malformation: thalidomide (CG
217), vitamin A and its precursors,
coumarin derivatives, folic acid antagonists,
iodide salts, ergot alkaloids, sexual
hormones, lithium, alcohol.
 thalidomide can cause hemifacial
microsomia in the OFS,

13-cis-vitamin A may induce
hemifacial
microsomia
or
mandibulofacial dysostosis,
 aminopterin as a folic acid
antagonist suppresses cell division
and can cause anencephaly,
 diazepam and acetylsalicylic acid
may participate in the development
of cleft lip, jaw and palate.
Due to potential neonatal adverse effects,
the following substances must not be
administered before birth: chloramphenicol,
nitrofuranes, sulfonamides, inhibitors
of prostaglandin synthesis (acetylsalicylic
acid, indometacin).
Embryonic or foetal defects can
also be caused by different viruses.
Herpetic viruses (for example
cytomegalovirus) can cause microcephalia,
hydrocephalus and microphtalmia.
Rubella
virus
can
cause
microphtalmia, deafness, cardiac disorders,
cleft
defects,
dental
aplasia
or abnormalities in tooth shape (rubella
embryopathy).
Toxoplasmosis as a parasitic
disease
can
cause
microcephalia,
hydrocephalus and microphtalmia.
The consumption of alcohol during
pregnancy can result in foetal alcohol
syndrome.
Children are small, have distinctive
facial characteristics – anterior distinctive
forehead, small eye openings, sometimes
antimongoloid
configuration
and
epicanthic folds, microphtalmia, low nasal
bridge and indistinct philtrum of the
narrow upper lip. The long lower jaw as a
sign of prognathism appears in puberty and
adulthood, thus making a picture
of relative hypoplasia of the middle part
of the face. Children always suffer from
mental retardation.
At nicotinism, the hypoxia may
cause a cleft defect. Ionizing radiation
may cause microcephalia.
14.2.2.2. General diseases of the mother
Congenital syphilis (syphilis congenita) is
an example of general diseases of the
mother that causes the abnormal shape
of teeth (Hutchinson teeth) and often
results in vertical open bite.
14.2.2.3. Developmental defects
Developmental defects include first and
second branchial syndromes which include
symmetrical
and
asymmetrical
irregularities of the eyes, ears, central part
of the face, jaws and teeth with potential
severe defects of soft tissues, chewing
muscles and adjacent skin.
Mandibulofacial
dysostosis
(dysostosis
mandibulofacialis)
is
a congenital disorder of the organs from
the first branchial arch, being characterized
by hypoplasia of the lower jaw.
The mandible is short, small, deflected
from the maxilla. The dentition has
therefore open occlusion, resulting in a
characteristic “bird face”.
Cleidocranial dysostosis with the
affected growth of the skull base and
suture
persistence
is
characterized
by
micrognathism
and
extreme
pseudoprognathism with reverse bite.
The dentition is characterized by
hyperdontia, fused multiple teeth and
multiple retained teeth.
The symptomatology of congenital
developmental defects include the cleft lip,
jaw, and palate. These can be found in the
Robin syndrome, Crouzon syndrome,
mandibulofacial
dysostosis,
and
cleidocranial dysostosis. Cleft defects are
serious congenital defects accompanied
with multiple abnormalities of individual
teeth and the groups of teeth (abnormalities
in the number, shape and position of teeth).
Cleft defects are also characterized by
abnormalities in the relationship between
dental arches.
One example of a systemic disease
is ectodermal dysplasia which is
accompanied with multiple aplasia
of individual teeth, i.e. hypodontia.
14.2.3. Factors affecting the postnatal
development
Factors that contribute to the development
of orthodontic abnormalities in a child
after birth either individually or
in combination include:
- birth trauma,
- mode of feeding, breast-feeding or bottlefeeding,
- bad habits, dummy or thumb sucking,
- mouth breathing,
- tongue protrusion (infantile swallowing),
- composition of a diet,
- consistency of food,
- premature loss of temporary teeth,
- premature loss of permanent teeth,
- retained eruption of first permanent
molars,
- dystopia of dental buds,
- injuries,
- hormonal effects.
14.2.3.1. Birth trauma
Older scientific literature reported the
cases where the use of obstetric forceps
resulted in damage to the jaw joint and
to the mandibular growth centre. This
suppressed the growth of the branch of the
lower jaw on the affected side, and caused
the asymmetry of the mandible with
braches of a different length. In the case
of bilateral damage, the lower jaw was
small, resulting in microgenia and the
characteristic “bird face” in an affected
individual. Nowadays, the use of obstetric
forceps is sporadic since complicated
and difficult birth is terminated surgically
by the Caesarean section.
14.2.3.2. Mode of feeding, breast-feeding
or bottle-feeding
Breast-feeding was always reported as an
important stimulating factor for the
anterior mandibular growth and thus for
the correction of neonatal prognathism.
Efforts of a suckling to pull the nipple with
the areola into the mouth by pushing
his/her lower jaw forward, sucking the
milk from the mammary gland through
lactiferous ducts and moving the liquid
food for swallowing - all this is
accompanied with the posterior movement
of the mandible and represents intensive
functional movements of the lower jaw,
which is a major stimulus of growth. This
stimulus can also be present at bottlefeeding provided that the sucker tube on
the bottle is sufficiently rigid and short,
having a hole which allows milk to drip
when it is turned upside down. During
feeding, the child is lying at an angle in the
mother’s arms and the sucking bottle is
held horizontally. At such conditions, there
is no difference between breast-fed
children and bottle-fed children.
The importance of breast-feeding
relies on other, general medical, hygienic
and psychological aspects.
However, children fed artificially
from a bottle show a higher rate of bad
habits.
protrusion of upper incisors. Lower
incisors are inclined to retrusion. This
results in the horizontal open bite.
A similar mechanism applies to the
sucking and biting the lower lip. If the
child puts the thumb or finger into the
mouth so that the sucked finger lies
horizontally, this may result in vertical
open bite between incisors. This
abnormality arises from sucking and biting
the tongue.
14.2.3.3. Bad habits
Fig. 14.1. Pressures acting on the dentition during
the sucking the thumb
Bad habits as defined in the etiology of
orthodontic abnormalities include dummy
sucking or thumb sucking. However, there
are many other bad habits such as sucking
the facial mucosa, lower lip, pillow’s
corner, toy, etc. Biting lips, nails, tongue,
pencil, etc. can also be examples of bad
habits.
Children of very young age usually
suck a dummy. If a child sucks a dummy
or thumb only before falling asleep or
occasionally during the day, a minor
irregularity of the dentition may occur (it is
usually horizontal or vertical open bite). If
the abnormality occurred in the temporary
dentition and a bad habit was eliminated
(i.e. it ended up before the age of 3 years,
this abnormality may be corrected
spontaneously. Irregularity is not then
transferred into the arrangement of the
mixed or permanent dentition.
However, sucking a finger (usually
the thumb) can have worse consequences
for the morphology of the dentition (Figure
14.1.). Sucking the vertically placed finger
or thumb will result in the fan-shaped, gap
At finger sucking as described above,
dental arches will become more distant, the
tongue will drop and the contraction
of facial muscles will result in the
narrowing of the upper dental arch.
The narrowing of the upper dental arch
will result in the lateral shift of the lower
jaw causing the cross-bite occlusion.
The distancing of lateral teeth will lead to
extrusion. This will raise the lower third
of the face and the lower jaw can rotate in
the posterior direction – this will contribute
to the formation of vertically open bite.
In comparison with dummy sucking, finger
(thumb) sucking is more obstinate,
and may persist into the school age,
and irregularities of the dentition are more
distinct. The size of all described
deviations depends on their duration –
on a period of time, strength and manner
of finger sucking by a child.
In this respect, dummy sucking is
less harmful and it is easier to wean the
child from this bad habit. An assumption
that sucking causes distal occlusion was
not confirmed.
14.2.3.4. Mouth breathing
Mouth breathing occurs:
 in individuals with chronic diseases
of upper airways, with allergic cold,
nasal
septum
deviation,
hypertrophic adenoid vegetations;
 in individuals who cannot make the
anterior closure of the mouth due to
the functional disorder of m.
orbicularis oris, the small length
of the lips, with congenital
flaccidity or scarring of the lips,
 as a bad habit in a child who will
learn to breathe through the mouth
more comfortably and will choose
the
more
comfortable
way
of
breathing.
This
applies
to habitual mouth breathing where
breathing through mouth persists
even
after
the
removal
of a mechanical obstruction.
Mouth breathing contributes to the
formation of distal occlusion, transversal
narrowing of the upper dental arch
(sometimes accompanied with unilateral or
bilateral cross-bite), the protrusion
of upper incisors, the drop of the tongue
and a loss of the anterior closure of the
mouth.
During mouth breathing, the lips
are slightly open, the tongue lies on the
lower dental arch and loses its contact
with the upper dental arch and the palate.
The lower lip may touch the palate and the
upper incisors will then protrude.
As mentioned above, mouth
breathing can be caused or accompanied
by "lip deficiency” – lips are short and
flaccid. However, this condition will not
always lead to mouth breathing because
a contact between the tongue and the lower
lip creates the adaptation anterior closure
of the mouth. The posterior closure of the
mouth allows a contact between the tongue
and the soft palate.
It follows from current opinions
that the role of mouth breathing
as an etiological factor of abnormalities
in the dentition and the orofacial system
was exaggerated in the past.
14.2.3.5. Tongue protrusion (infantile
swallowing)
At the normal swallowing (when
temporary teeth are not erupted), the
tongue is pressed in between toothless jaws
and together with the lips it prevents the
outflow of liquid food out of the mouth.
This is infantile swallowing seen
in suckling infants. After the eruption
of teeth, the normal swallowing is
characterized by tight lips, upper and lower
teeth being in maximum intercuspidation,
and the tongue leaning against the palatinal
surfaces of the upper incisors and the
anterior palatinal surface.
At the habit of thrusting the tongue
forward, i.e. at persistent infantile
swallowing, the tongue does anterior
movement between the upper and lower
front teeth during phonation. Dental arches
are not in contact. The pressure of the
tongue results in the protrusion of upper
incisors and reduction in the vertical overbite up to the vertical open bite (Fig. 14.2.).
This endogenic protrusion of the
tongue is accompanied with the increased
activity of the tongue in speech.
The contraction of circumoral muscles is
then seen upon swallowing.
The adaptation position of the
tongue can be found at distal occlusion
with the protrusion of upper incisors where
the lips are flaccid. In such cases, the
tongue or lower lip creates the anterior
closure of the mouth through the contact
with palatinal mucosa. Swallowing
proceeds with dental arches being
separated; if the tongue is placed habitually
on lower incisors’ cutting edges, the
vertical overbite may diminish to vertical
open bite.
Literature data assume reverse
mechanism in which the tongue uses the
present gap between front teeth for
protrusion.
14.2.3.7. Consistency of food
Fig. 14.2. The balanced pressure of the lips and
tongue at a regular swallowing act (the upper part
of the figure). Tongue protrusion in infantile
swallowing forms vertically open occlusion (the
lower part of the figure).
14.2.3.6. Composition of a diet
For the healthy development of an
individual, the diet should contain enough
vitamins, minerals, trace elements,
unsaturated fatty acids, a minimum of free
radicals. Experiments in animals have
shown major deformation of jaws and
bones when animals were fed with feeds
deficient in vitamins C and D.
However, the application of this
knowledge to man is not possible. Human
nutrition – even if its composition is not
optimal – is not an etiological factor to
cause irregularities in the dentition and
jaws, except for the case that it contains
cariogenic components and oral hygiene of
a particular individual is poor. In such
cases, the diet may contribute to dental
caries, thereby secondarily affecting the
development and arrangement of the
dentition.
The effect of function on the development
of jaws is well known. Experimental
studies in animals (rats) have confirmed
the difference between functional effects of
hard and soft food on the development of
jaws, dentition and surrounding soft tissues.
Jaws and the dentition of primitive
man show certain characteristics (different
from the jaw and dentition arrangement in
contemporary man) that indicate the
greater functional use of these organs. Jaws
had a larger alveolar part. The dentition
showed signs of occlusion and proximal
abrasion.
However, a number of irregularities
of the orofacial system have increased
significantly over the last two centuries.
Abnormalities do not result from
phylogenetics. Dentition irregularities
appear to be associated with thermally and
mechanically treated food that does not
provide sufficient stimulation for the
growth of the jaw and do not support
abrasion particularly in proximal surfaces
of teeth. This results in an increasing
number of abnormalities such as the
crowding of teeth, deep bite, the retention
of teeth, teething problems with third
permanent molars (dentitio difficilis).
14.2.3.8. Premature loss of temporary
teeth
Temporary teeth fulfil a number of
functions. They also act as physiological
spacer savers keeping the space for
permanent teeth.
However, consequences of the
premature loss of temporary teeth is
different in every individual and cannot be
solved simply with a single general spacer.
A variety of consequences depends on the
following factors:
 on the segment of the dental arch
where the loss occurred
 on the dental age at which the loss
occurred
 on the arrangement of the dentition,
particularly on dental arches
It appears that the risk associated with the
premature loss of a tooth (and thus with the
loss of space) increases in the dental arch
in the distal direction. In most cases, the
loss of incisors has minimal effects – there
are physiological gaps between temporary
incisors. In addition, at the displacement of
incisors, the frontal segment of the
dentition extends physiologically by
growing.
The loss of a temporary incisor due
to caries does not usually cause irregularity
in the dentition. The same applies to the
traumatic loss of a temporary incisor if it
does not affect the bud of a permanent
incisor, for example by dilaceration.
The premature loss of temporary
canine poses other risks. It is not caused by
caries but by the lack of space which
causes the root of a temporary canine to be
resorbed prematurely by a small permanent
incisor. Such a phenomenon can be seen
more frequently in the lower rather than in
the upper jaw. The place of a temporary
canine in the dental arch will then be
occupied by the permanent lateral incisor
and the permanent canine will erupt
outside the dental arch because of the lack
of space. The unilateral loss is also
associated with a major shift of the centre
of the dental arch towards the affected side.
It should be pointed out here that the
extraction of a temporary canine is wrong
and incompetent solution used by some
dentists to solve the crowding of lower
incisors, resulting in a major shift of the
centre of the dental arch. Such a condition
is difficult to correct by orthodontic
therapy.
Even with effective preventive care
of child’s dentition, temporary molars may
be lost due to caries. The lack of space
should also be taken into account at the
destruction of clinical crowns or at the
insufficiently treated proximal caries in the
above-mentioned teeth (Fig. 14.3.). The
loss of space is more significant when the
crown destruction or tooth extraction has
occurred early and when the dentition has a
tendency to crowding. In exceptional cases,
the gap left after the loss of temporary
molars is retained spontaneously by the
intercuspidation of first permanent molars
or by the extrusion of a temporary
antagonist.
At a premature loss of first
temporary molars, the second temporary
molar and the first permanent molar will
shift mesially, without mesial rotation and
mesial inclination. Front teeth will expand
along the arch and there will be a shift in
the centre of the dental arch at the
unilateral loss.
Fig. 14.3. The shortening of the dental arch by the
destruction of teeth in the supporting zone of the
dentition (down: well shaped fillings stabilize the
regular length of the dental arch)
The premature loss of second,
temporary molars has significant and
serious consequences. If the loss occurs
before the eruption of the first permanent
molar, the first permanent molar will erupt
mesially from its regular place, i.e. there
will be a mesial shift. The extreme
shortening of the lateral segment of the
dental arch (the supporting zone of the
dentition), will result in a lack of space for
the later eruption of permanent teeth which
will erupt outside the dental arch. In the
upper jaw, the permanent canine will erupt
in the vestibular direction (the palatinal
eruption of the second premolar occurs less
often), whereas in the lower jaw the second
premolar will erupt in the lingual direction
or remain retained. This will result in the
secondary crowding of teeth in the
dentition.
If the second temporary molar is
lost after the eruption of the first
permanent molar, the first permanent
molar will then shift mesially, incline
mesially and rotate mesially in the upper
jaw around its palatinal root. In the lower
jaw, it will shift mesially, show a
significant mesial inclination and partial
mesial rotation. The resultant shortening of
the dental arch will bring the possibility of
secondary crowding of teeth.
The risk of secondary crowding is
greater in the upper dental arch than in the
lower arch. The lower jaw has some space
resulting from the difference between the
broad temporary second molar and the
second premolar. In addition, the shifts of
teeth in the lower jaw (because of its
anatomy) are generally small.
With regard to the dental age, it is
necessary to distinguish the losses before
and after the eruption of the first
permanent molar – see above.
The consequence of a premature
loss of a temporary tooth depends on a
degree of crowding in the developing
dentition. Loss of place is minimized in
regularly developed jaws and spacious
dental arches. On the other hand, the
premature loss of temporary teeth
deteriorates the existing crowding of teeth.
The premature loss of teeth in the lateral
segment of the lower dental arch often
results in deep bite which arises from the
retrusion and distal shift of lower front
teeth.
14.2.3.9. Premature loss of permanent
teeth
The premature loss of a permanent tooth
means the loss of a permanent tooth before
the completion of the permanent dentition.
In the distal segment of the dentition, this
often concerns the premature loss of the
first permanent molars which are extracted
due to very complicated or failed
orthodontic treatment. In the frontal
segment of the dentition, the premature
loss usually involves incisors that are lost
as a result of injury. This also includes the
cases of missing permanent incisors due to
aplasia, which has identical clinical
features.
The premature loss of the first
permanent molars results in the shift and
inclination of adjacent teeth into the gap
and the eruption of an antagonist into
supraocclusion. The inclination of an
adjacent tooth into the gap is largest for the
lower permanent second molar, in the
mesial direction. The dentition may also
show deep bite and the physiological
overbite may increase. Change in the
height of the bite is more pronounced if the
upper incisors are in retrusion. At multiple
prematurely missing teeth, the dental arch
will decrease. In the case of the upper
dental arch, this may result in reverse bite.
The premature loss or absence of
permanent front teeth result in irregular
shifts and inclinations of the remaining
teeth (including pillar teeth) in the
respective dental arch. In the case of the
asymmetric loss or the absence of a
permanent front tooth, the centre of the
dental arch will be shifted. Shifts and
inclinations of teeth in combination with
the shift of the centre represent serious
functional and aesthetic defects of the
dentition.
14.2.3.10. Retained eruption of first
permanent molars
This happens when the first permanent
molar is insufficiently erupted and retained
by the distal surface of the temporary
second molar. This can be caused by the
crowding of teeth but also by the abnormal
direction of the germinal crypt of a tooth the tooth calcifies in the abnormal
direction. The retained tooth remains in
infraocclusion, cannot be cleaned properly
mechanically, plaque accumulates on the
tooth making it susceptible to caries.
14.2.3.11. Dystopia of dental buds
The crypt where the mineralization of a
tooth takes place can be formed
abnormally, dystopic or rotated. Such
change creates conditions for the irregular
direction of the mineralization and eruption
of a tooth. In some teeth, such deviations
occur more often. Dystopia usually affects
the upper permanent canines whereas the
dystopia of a bud usually occurs in lower
second premolars and lower third molars.
Upper permanent canines are
mineralized under the orbit’s base and
from here they descend via the long
eruption pathway to the dental arch. Along
the eruption pathway, they can be deviated
in the palatinal direction where the
temporary canine will persist and the
palpable prominence may be found in the
palate. The eruption pathway of canines
may deviate in the vestibular direction –
with the mesial inclination being directed
towards the root of the small incisor. Their
dislocation leads to the horizontal position
below the base of the nose or upwards into
the apical base of the jaw, i.e. into the
point of the transition of the alveolar part
and the jaw.
The abnormal development of the
incisor can be indicated by the abnormal
finding for the upper small incisor. If this
tooth is tiny or missing due to bud aplasia,
this may indicate the palatinal dystopia of
the permanent canine. Similarly, the
abnormal placement of the permanent
canine can be assumed if there is the
protrusion of the small incisor, which
occurs if the canine is deposited too high in
the vestibular direction or too low in the
palatinal direction. It should be emphasised
that the abnormal placement or eruption of
the canine can be expected in children
whose parents had palatinally located
canines or slowly developing small
incisors or when these teeth had irregular
shape.
The early diagnosis of potential
dystopia or the expected abnormal eruption
of the permanent canine is very important.
At the age of 8-9 years, the canine bud
should be palpable in the vestibular fornix
in the upper jaw as a distinct palpable
prominence. The exchange of temporary
canine for a permanent one should proceed
symmetrically in both halves of the jaw, in
a time interval not longer than six months.
The finding of the solid temporary canine
on one side of the dental arch and the
erupting or erupted contralateral permanent
canine indicates the potentially abnormal
development and the placement of the
permanent successor of the solid temporary
canine.
If the permanent canine is not
palpable at the age of 10 years, or if the
replacement of the temporary canine
proceeds asymmetrically, immediate X-ray
examination is indicated. The Pordes
technique (projection) of two images
proved useful as it helps to determine the
vestibular, central or palatinal localization
of the permanent canine. In sporadic cases,
the extreme abnormal localization of the
canine requires the posteroanterior or axial
X-ray image of the skull. Furthermore, the
X-ray examination allows one to identify
or exclude the pathological resorption of
the root of the small incisor or the
resorption of the root of the great incisor if
this tooth is not founded. It should be
emphasized that root resorption can be
asymptomatic; the affected teeth remain
vital and solid although the resorption
process reduced the root by one third or
one half of its original length.
14.2.3.12. Injuries
Dental injuries leading to the premature
loss of temporary or permanent teeth result
in the abnormal tangential shifts and
inclinations of teeth and gaps of a different
size in the dental arch.
Dislocated fractures of the alveolar
part of the jaws may result in irregularities
in the relationship of the group of teeth
such as reverse bite or cross-bite . Late
diagnosed fractures of the lower jaw’ joint
process can lead to the disorders of the
growth of the mandibular branch.
Post-traumatic or post-operative
scars located in lips or cheeks may prevent
the development of dental arches and cause
their deformation. If this occurs in the
upper dental arch, the retrusion of upper
incisors may result in reverse bite.
14.2.3.13. Hormonal effects
Human growth hormone (somatotropin)
deficiency results in nanism which is
accompanied by the slow development and
growth of jaws and the slow eruption of
teeth in response to the slow growth of
bones. In addition, a mismatch in jaw and
teeth sizes (teeth are not affected by the
size defect), leads to the crowding of teeth.
An excess of the growth hormone results in
gigantism or acromegaly. The enlargement
of the alveolar part of the jaws and the
mandibula is one of its characteristic
symptoms.
Thyroid hormone deficiency results
in cretenism accompanied by macroglossia,
the slow growth of jaws and the slow
eruption of teeth. Temporary teeth persist
in the dentition whereas permanent teeth
remain retained.
On the basis of vast knowledge of
potential etiological factors giving rise to
orthodontic abnormalities, it is advisable to
consider the options of postnatal
prevention.
14.3. Scope of the postnatal prevention
of orthodontic abnormalities
Thorough prevention of orthodontic
irregularities
is
limited.
Multiple
combinations of inheritance, internal and
external etiological factors make the
dentist’s task very difficult.
Whereas
preventive
measures
succeeded to reduce the rate of infectious
diseases and caries (in a number of
countries), the rate of orthodontic
abnormalities has not yet been lowered in
any part of the world.
In spite of this, the role of
prevention of malocclusions must not be
underestimated. In individual cases, it
plays an important and undeniable role.
The practical performance of prevention
varies.
Prenatal prevention falls within the
scope of the physician who takes care of
pregnant women. It is fully overlapped
with general medical care and general nonmedical care ensuring the healthy
development of the foetus.
After birth, postnatal prevention
falls within the scope of a paediatrician and
parents, and later within the scope of a
dentist and parents.
Preventive measures in dentistry
can be combined with early orthodontic
treatment. The aspects of prevention
ranked in a chronological order:
 to emphasize the advantages of
breast-feeding,
 to prevent bad habits,
 to strengthen the lip closure of the
mouth by myotherapy,
 to control the abnormal effect of
the tongue,
 to use the proper consistency of
food,
 to remove forced reverse bite or
cross-bite,
 to prevent the consequences of the
premature loss of temporary teeth
 to prevent consequences of the
premature loss of permanent teeth,
 to apply procedures in order to
control dystopic dental buds and
the retained eruption of first
permanent molars,
 to control hyperdontia by using
early procedures.
14.3.1. Preferring
bottle-feeding
breast-feeding
to
From an orthodontic point of view, the
importance of natural breast-feeding relies
on the fact that breast-fed children have
less inclination to bad habits and the
abnormal tongue position at swallowing as
compared to the children fed from a bottle.
From a general point of view, in order to
prevent bad habits, the child should be
breast-fed according to his/her wishes
rather than in regular intervals. In a period
before feeding when the child is hungry
and does not get milk, he/she starts to suck
his/her fingers. In a period after breastfeeding, his/her desire to suck his/her
finger is greater if he/she did not get tired
by sucking the milk or if he/she made only
little effort to suck the milk.
For these reasons, the period of
feeding should not be shortened even in the
case of bottle-feeding. The child should
drink from a bottle for a sufficiently long
period of time to get tired and fall asleep.
The bottle therefore should be equipped
with a sucker tube with a small opening.
The purpose of such measures is to help to
resemble natural conditions of breastfeeding during bottle-feeding, particularly
the natural position of the tongue and the
anterior shift of the lower jaw.
14.3.2. Prevention of bad habits
Dummy sucking before falling asleep or
occasionally during the day (provided the
dummy has a proper shape) can be
tolerated in very young children. The
dummy should be short, rigid, preferably a
NUK type (Fig. 14.4.). Dummy sucking is
much less harmful than finger sucking. It is
easier for a child to unlearn dummy
sucking. Respective irregularities of the
dentition are usually minor or less
significant. Attempts to wean a child from
dummy sucking may pose a risk that the
child will start to suck fingers. Finger
sucking usually brings about abnormal,
more significant changes in the dentition.
Radical attempts to wean this bad
habit from children under the age of 3
years are not therefore recommended.
However, the age limit is very individual
and may vary depending on the mental
maturity of a child. In addition, it is
assumed that when this bad habit is
removed before the age of 3 – 4 years,
potential changes in the dental arches will
be corrected spontaneously and will not be
transmitted into the permanent dentition.
However, if it is desirable to wean
the child from the bad habit, the methods
used should be mild and gentle rather than
radical or violent. An example of such a
radical procedure is the use of a rigid cuff
slipped over the child's elbow in order to
prevent him from bending his/her arm. The
weaning of the child from the habit is
demanding and requires good cooperation
of parents. Parents’ behaviour should be
calm, without reproaches, neurotic
manifestations, or threats. The child’s
attention must be distracted as much as
possible and engaged in some kind of
activity.
In older children in whom bad
habits persist, it is advisable to combine a
psychological approach with therapy using
a vestibular screen. The vestibular screen is
a plate made of resin or plastic material
that fills the whole vestibule of the mouth.
Its purpose is to obstruct habitual abnormal
activities such as finger sucking and help
restore the natural balanced tension of the
tongue, lips and cheeks. This also restores
the normal development of the dentition
(Fig. 14.5.).
Fig. 14.5. Vestibular screen
Fig. 14.4. A NUK-type dummy
14.3.3. Suppression of mouth breathing,
the strengthening of lip closure of the
mouth
Although current opinions on mouth
breathing as a cause of orthodontic
abnormalities are less rigorous, one can
choose a suitable method to restore mouth
breathing in order to strengthen the regular
development of the dentition.
The following methods can be used:
 causal
otorhinolaryngological
procedures such as adenotomy,
tonsilectomy, the correction of
nasal septum deviation,
 the use of a perforated vestibular
screen. The screen has several
larger holes which allow the child
to breathe through the mouth in the
beginning of therapy. Holes are
gradually
closed
using
polymerizing resin, the screen helps
a child to train nose breathing. This
kind of therapy is prescribed by the
orthodontist.
 muscular exercises, i.e. myotherapy.
The purpose of this method is to
strengthen the lip closure in
children who have flaccid, slightly
open lips, usually with the
protrusion of upper incisors.
Exercises rely on blowing cheeks
and transferring the air from one
side of the mouth to the other. The
child can also do these exercises
with lukewarm water. Air-blowing,
whistling, or doing exercises with a
vestibular
screen
are
also
recommended. The child pulls the
screen’s ring out of his/her mouth
while having his/her lips closed
tight.
14.3.4. Controlling the effect of tongue
protrusion
The oral screen is used to fulfil this
prophylactic task. It can consist of a resin
plate placed in the mouth between the
tongue and the dentition. For stable fitting
in the mouth, the oral screen is designed to
have a relief of oral surfaces of individual
teeth in the upper and lower dental arches.
The same task can be fulfilled using a
plate-like recording orthodontic appliance
– palatable plate. It is designed to have a
wire grating coming out of it against the
tongue preventing tongue protrusion. Such
appliances are used by orthodontist for
prophylactic purposes.
14.3.5. The importance
consistency of food
of
proper
After the eruption of temporary molars, the
child can perform mastication, lateral
chewing movements. From this period, the
child should chew solid food such as meat,
bread crust, hard fruits, raw vegetables. For
the development of chewing muscles and
for proper swallowing, it is important to
switch the child from liquid food to
feeding using a spoon and to solid food.
The prolonged use of liquid or
mixed mushy food will lead to muscular
flaccidity due to the insufficient learning of
proper chewing and swallowing habits.
14.3.6. Measures to help eliminate
forced reverse bite or cross-bite
Forced reverse bite or cross-bite usually
arise due to the narrow upper dental arch
or the abnormal occlusion of individual
teeth or groups of teeth in the frontal or
lateral segment of the dentition. The forced
abnormal relationship between dental
arches such as reverse bite or cross-bite
also occurs due to the functional deviation
of the lower jaw.
Forced reverse bite is usually
associated with the abnormal occlusion of
temporary canines with temporary incisors,
whereas forced cross-bite usually means
the abnormal occlusion of temporary
molars, sometimes together with temporary
canines.
Corrections of abnormal occlusion
of temporary teeth are very important and
should be performed in the temporary
dentition and early mixed dentition as early
as possible. The necessary correction of
abnormal occlusion of temporary teeth
means the early recontouring of teeth. In
the case of forced cross-bite, it is
sometimes necessary to perform the partial
recontouring of cusps of the first
permanent molars.
The recontouring of cutting edges
and cusps should provide bevelled surfaces
which help achieve the required labial and
buccal shift of the upper abnormally
occluding teeth. After recontouring, the
teeth are treated using fluoride preparations
(Fig. 14.6.).
Fig. 14.6. Recontouring of temporary teeth: A –
Recontouring of temporary teeth in reverse bite, B
– Recontouring of temporary canines in reverse bite,
C – Recontouring of molars in cross-bite
If reverse bite is still present in the
combined dentition and if the permanent
upper incisors show cross-bite, it is
suitable to perform a prophylactic
procedure that the child bites with his
erupting permanent upper incisor into the
handpiece of a toothbrush or into a wooden
spatula. This will force the erupting tooth
to physiological overbite and overjet. The
object into which the child bites, should be
placed under the controlled tooth
maximally vertically, perpendicularly. The
correction described uses the force leading
to tooth protrusion. The anemization of the
marginal gingiva on the labial surface of a
tooth indicates correct performance (i.e.
correct pressure).
14.3.7. Prevention of consequences of the
premature loss of temporary teeth
The most effective prevention of the
premature loss of temporary teeth relies on
the thorough prevention of caries and on
the proper dental treatment of the
temporary dentition including fluoridation,
the treatment of temporary teeth, proper
diet and regular and effective oral hygiene.
The child should be taught proper
oral hygiene such as the regular cleaning of
teeth from the eruption of first teeth. Early
treatment of the temporary dentition is
important, particularly in the case of teeth
in the supporting zone of the dentition,
primary
temporary
second
molar,
temporary canine and temporary first
molar. Care of these teeth prevents not
only their loss but reduction in their
mesiodistal dimensions due to caries. On
the other hand, the premature loss of
temporary teeth and the destruction of their
clinical crowns by caries will result in the
abnormal mesial shift of first permanent
molars, i.e. the shortening of dental arch
and the shift of the centre of the dental arch.
The crowding of teeth will occur or if it is
present, it will become worse.
 When treating the premature loss of
temporary teeth, the attending
dentist will have to perform the
following steps:
 to record and measure the size of
the resultant gap in the dental arch
using a slide gauge and check the
gap in regular intervals,
 to evaluate the state and type of the
dentition and make a spacer for a
child,
 to propose adequate asymmetric
(balanced)
or
compensation
extraction in a child. Asymmetric
balanced extraction means to
extract the same tooth in the second
half of the same dental arch.
Compensation extraction means to
extract the same tooth in the dental
arch of the opposite jaw.
The indication of the spacer requires close
cooperation between a paediatric dentist
and orthodontist. Spacers in form of
paediatric prosthetic appliances are
prescribed and designed by paediatric
dentists whereas orthodontists usually
prescribe the spacers as part of therapeutic
orthodontic instruments they are using.
Generally, spacers should be
applied in regular dentitions where the
minor crowding of teeth is present or in the
dentitions with the significant crowding of
teeth, if the eruption of a permanent tooth
to replace the lost temporary tooth occurs
in more than ½ - 1 year. The dental age
should therefore be considered.
Spacers are designed as fixed or
removable spacers. Fixed, solid spacers
consist of metal rings fitted and cementbonded to the distal tooth of the gap with
the metal construction leaning against the
mesial tooth (Fig. 14.7.) They are used in
the case of the loss of one temporary molar.
Their disadvantage is that plaque is
accumulated on their surface and under
them, which poses a risk of caries
formation on the teeth adjacent to the gap.
Removable spacers are partial
prosthetic appliances. They are made with
or without clips. Removable spacers are
useful in the case of the extensive losses of
teeth where they extend the working
surface of the dentition, improve phonation
and rehabilitate the child from a
psychological point of view. This applies
particularly to spacers applied in children
at the premature loss of temporary incisors.
Fig. 14.7. Fixed spacers
Removable spacers should follow
the growth-induced changes in jaws and
dentition. It is therefore necessary to check,
adjust or replace them frequently. Their
main disadvantages are as follows:
children sometimes refuse them, chronic
trauma of the mucoperiosteum under the
spacer may result in prosthetic stomatitis,
and self-cleaning of the dentition is
difficult. Enamel demineralization may
occur on oral surfaces of teeth.
As reported by foreign authors, the
use of spacers is problematic and
questionable for the following reasons:

The use of spacers allegedly causes
problems in very young children.
 Even the prolonged use may not
prevent a potential orthodontic
abnormality which may necessitate
long-time therapy lasting for years
(orthodontic therapy).
 The use of a spacer requires
optimum cooperation of a child.
The spacer should be borne
regularly. Otherwise, it may fall out
and fail to fulfil its function.
The tooth itself is an ideal spacer. This is
why many authors recommend the dentists
to focus primarily on the quality preventive
and therapeutic care of the temporary
dentition, thereby reducing the number of
teeth extracted because of caries. They also
recommend the use of conventional
methods of pulp treatment and endodontic
therapy in temporary teeth. If it is
necessary to extract a temporary tooth,
asymmetric (balanced) and compensation
extraction should be performed in the
remaining
dentition.
Asymmetric
(balanced) extraction prevents the shift of
the centre of the dental arch, thereby
preventing a very complicated correction
of such a defect using a solid orthodontic
appliance. The compensation extraction
will then serve to retain the satisfactory
intercuspidation of lateral teeth.
Solving the premature loss of the
upper temporary first molar at the regular
relationship of dental arches (normal
occlusion) may serve as an example. In
this case, balance extraction of a temporary
first molar in the second half of the dental
arch is recommended.
The above-mentioned extraction
methods can be used in a radical procedure
where the unilateral loss of the upper
temporary first molar is solved by the
balance extraction of the same tooth in the
second half of the dental arch and by the
compensation extraction of both first
temporary molars in the opposite jaw.
Practical experience has shown that
the recommended extraction methods are
suitable for use provided that

the teeth considered for balanced or
compensation extraction are of
poor quality, have poor prospects,
 the aplasia of the permanent lateral
tooth was found in the particular
segment of the dental arch, and it is
therefore necessary to release
permanent molars to a mesial shift.
Generally, the temporary tooth will be
extracted when it is confirmed that the
permanent tooth which will displace this
temporary tooth is dystopic and will
erupt/is erupting in the abnormal, deviated
direction. This is usually accompanied
with the slow resorption of the root of the
temporary tooth and it would be a mistake
to wait for the elimination of the temporary
tooth.
14.3.8. Prevention of consequences of the
premature loss of permanent teeth
As discussed in the etiology of orthodontic
irregularities, permanent first molars of
poor quality and uncertain prospects
located in the lateral segment of the
dentition are usually extracted. Decision as
to whether to extract these teeth or retain
them in the arch should be made in time.
If permanent first molars in the
crowding dentition are to be extracted at
the age of 8 – 9 years, the basic irregularity
of the dentition will usually improve. In
addition, the permanent second molar will
erupt after the mesial shift without
inclination into a contact with the second
premolar. At older age, it is suitable to
extract permanent first molars if the
crowding of the premolar segment of the
dentition is extensive. Erupting premolars
will accommodate the place of the
extracted permanent first molar, and the
permanent second molar will not be
endangered by adverse mesial inclination.
Unlike
the
above-mentioned
knowledge, the extraction of permanent
first molars is not recommended in the
following cases:
 there is enough space in the dental
arch,
 the aplasia of the second premolar,
 cover bite
The extraction of permanent first molars in
the upper jaw is not suitable in the
presence of edge-to-edge bite or
interocclusion. In such a case, the
extraction of upper permanent first molars
is associated with a risk that the reverse
bite will be formed or will deteriorate (if
present)
and
that
the
abnormal
anteroposterior relationship of dental
arches will become more distinct.
On the other hand, the extraction of
lower permanent first molars is not
recommended in the case of normal
occlusion and distal occlusion. This would
deepen the occlusion and increase the
incisal ledge.
When a permanent tooth is lost, it is
necessary to take into account the
subsequent extrusion of an antagonist, until
the gap closes. Gap closure can be
accelerated by the recontouring of dental
cusps adjacent to the gap, to make guiding
surfaces which help the motion of teeth
into the gap, as required.
The early loss of permanent front
teeth requires cooperation of paediatric
dentist, practical dentist and orthodontist
and prosthetic technician.
In such cases, the therapeutic plan
is developed before the eruption of the
permanent canine and is based on the gap
closure by shifting adjacent teeth (which is
more suitable for a patient) or on the
maintaining of the gap in the dental arch, if
the permanent canine in the dentition has
already erupted.
With the former variant of the
therapeutic procedure, the shifted teeth will
be fitted with full-cover crowns whose size
and shape correspond to those of the teeth
that are missing in the dental arch and that
were displaced by the shifted teeth.
In the latter variant, the gap is
maintained using a spacer until the adult
age where it is treated using a prosthesis.
In some clinics, removable plate spacers
indicated for a period of the development
of the dentition are replaced with adhesive
bridges after the eruption of permanent
canines.
Our experience have shown that
when the development of the dentition is
completed (i.e. after the eruption of
permanent second molars), it is advisable
to replace the removable plate spacer for a
removable
spacer
to
enable
the
dentomucosal transmission of chewing
pressure. Such a spacer consists of a
reduced chromium-cobalt plate which
bears artificial teeth and is attached to the
dentition by means of three-arm clamps.
14.3.9. Early control procedures at the
dystopic placement of dental buds and
at the retained eruption of first
permanent molars
The dystopic irregular placement of a
dental bud is usually observed for
permanent upper canines. If the degree of
this irregularity is low, the bud of the
permanent canine is shifted in the jaw in
the slightly vestibular or palatinal direction
and has a satisfactory axial position, i.e. it
does not have a major mesial or distal
inclination.
Early treatment relies on the early
extraction of the temporary canine and in
the retention, or extension of the gap in the
dental arch.
If the permanent canine does not
erupt spontaneously, it is possible to
stimulate its eruption using a stimulating
device such as a simple resin palatal plate
with an artificial tooth that fits the
mucoperiosteum of the upper alveolar
process in the place of the former extracted
temporary canine. The transmission of the
chewing pressure through the artificial
tooth stimulates the eruption of the
permanent tooth. The orthodontic screw
inserted into the stimulating appliance
helps enlarge the gap in the dental arch, as
necessary.
The treatment of permanent canines
in major dystopic localization is a subject
of specific orthodontic or surgical
treatment.
The retained eruption of the
permanent first molar will damage the
dentition by destroying the crucial pillar
tooth. In addition, the retained molar will
remain in infraocclusion, cannot be
cleaned properly, plaque is accumulated on
it, which gives rise to caries. The retained
molar must be checked regularly. It
remains in the dental arch until the
exfoliation of mesially located second
temporary molar. If its eruption does not
occur, removal by extraction is considered.
Foreign literature recommends
desimpaction to be performed at the
retained eruption of the permanent first
molar. In this case, the permanent first
molar is released from the contact with the
adjacent temporary second molar by
pulling a soft brass wire (initially 0.5 mm,
later 0.6 mm) around the point of contact
of these two teeth. The tightening of the
wire is performed once a week. The
separation of teeth performed in this
manner should contribute to the release of
the eruption of the permanent first molar.
14.3.10. Early control procedures at
hyperdontia
Hyperdontia means the increased number
of teeth. True hyperdontia is the condition
of having supernumerary teeth in addition
to the regular number of teeth.
In the upper jaw, in the region of
great incisors, one or more supernumerary
teeth are founded. If they are located near
the centre of the jaw, they are called
mesiodens. Such supernumerary teeth will
erupt into the mouth or remain retained.
They may cause diastema, retention of one
or two great incisors or irregularities in
their location.
In the case of the retention of a
supernumerary tooth, the prophylactic
procedure relies on the properly scheduled
surgical extraction. This means that the
supernumerary tooth must be removed
sufficiently early in order to stop the
potential retention of the permanent incisor
(the prolonged period of retention
decreases the tooth’s ability to erupt). The
treatment of the supernumerary tooth must
also be scheduled quite in advance, i.e.
after the mineralization of roots of
permanent teeth (located in the area of the
surgical procedure) is completed. The
surgical procedure performed before the
completion of mineralization may have a
negative effect on the regular development
of teeth.
Conclusion
Specific issues associated with the
prevention of damage to dental tissue and
the periodontium during orthodontic
therapy are rather far from general
prevention in orthodontics.
The motion of teeth at the
correction of orthodontic abnormality is
realized through the orthodontic force
transferred to the dentition by means of an
orthodontic appliance. The orthodontic
force will induce bone resorption and
apposition, causing the remodelling of the
dental bed and the jaw’s alveolar process.
It also causes the remodelling of
periodontal fibres, and the resorption of
cement on the root of the control tooth at
certain conditions.
The orthodontic force must be
sufficiently strong, last for the required
period of time, and has a suitable direction
so that the remodelling of the tissue can
proceed without any damage and in the
manner required for the correction of
orthodontic irregularity.
Prevention of such damage is
therefore one of the major tasks of
specialized orthodontic therapy and due to
its specificity it reaches beyond the scope
of general orthodontic prevention.