TERNOPIL STATE MEDICAL UNIVERSITY
name of I. Gorbachevsky
LECTURE
From propedeutic of therapeutic pediatric dentistry
for students of II course of dentist faculty
Introduction to the pediatric dentistry. Anathomicalmorphological and X-ray features of teeth - jaw system at
children in different age-old periods.
Ternopil– 2007
A pediatric dentistry is one of the most difficult disciplines. It studies the
dentistry diseases based on knowledges from age-old ones anatomical – functional
features of child, its development in аntе -, intra -, and postnatal periods of life.
Child's population makes the considerable particle of population of our country
that is why the sphere of help touches the most perspective part of society. Level of
dents diseases at children extraordinarily high. Sickly state of cavity to the mouth
badly influences on psychological and physical status of child. From a toothache,
discomfort in the cavity of mouth, from inferiority of dental row a child renounces
meal, badly chews her. Teeth which are not treating always are the source of
infection, allergy, and lower resistance of organism on the whole. Sick temporal
teeth are reason 85% heavy festering – inflammatory processes result in teeth –
jaws deformations.
Complication of work of child's doctor – dentistry consists in that he must take
into account not only symptomatic of disease but also anatomical- physiology
features of child's organism in a certain period of development. To set a diagnosis
and to choose the method of treatment, a doctor must own not only by basic
dentistry manipulations but also to have knowledge from pediatrics about the
periods of growth and development of child, feature of its functional state.
Our object, propedeutic of therapeutic pediatric dentistry enables to the students
to lay hands on certain skills of treatment of teeth and his complications decay on
phantoms. Knowledges purchased thus, you use in the process of work directly
with patients. On phantoms models and remote teeth students meet with the basic
periods of development and resorbtion of roots of baby teeth, by the periods of
forming of roots of the second teeth at children, and also seize by basic
manipulations from preparing and stopping of carious defects of teeth, conduct
endodontic interference in teeth with the different stages of their development.
DEVELOPMENT OF TEETH-JAWS SYSTEM AT CHILDREN
A primary oral cavity at an embryo has the appearance of narrow crack which is
limited by five sprouts of branchial arcs. The overhead edge of mouth crack is
formed by an odd frontal sprout and located on sides from him by supramaxillary
sprouts — the appendix first branchial arc. The lower edge of mouth crack is
limited by two lower- jaw sprouts which also are derivative the first branchial arc.
Transferred sprouts not only limit a mouth crack but also form the walls of mouth
cavity — future cavity of mouth.
Teeth are derivative mucus shell of oral cavity of embryo. Enamel organs develop
from the epithelium of mucus shell, and from a mesenchyma, which is under an
epithelium is dentine, pulp, cement, hard and soft fabrics circumferential a tooth
(parodontium).
(See a fig. 1, 12)
The odontogeny passes in three stages: the embryos of teeth are formed in the first;
differentiation of dental embryos passes in the second, in the third is formation of
teeth.
In the first stage, on 7-8 week of embryo development, on the overhead and
lower surfaces of cavity of mouth there is the bulge of epithelium is dental plate
lamina enamelare, which grows in an inferior mesenchyma. On turned to the lip or
cheek of surface of dental plate due to subsequent excrescence of epithelium form
tube educations which grow afterwards into the enamel organs of temporal teeth
are formed. In every dental plate is formed for 10 educations which answer the
embryos of temporal teeth. On a 10th week in enamel organs, submerging into
their wall, a mesenchyma, which forms dental baby's dummies papillae dentales,
grows in. To the end of 3rd month of development enamel organs move away from
a dental plate, but keep with her connection by mediocrity of epithelial bunch are
necks of enamel organ. Round an enamel organ due to the compression of
mesenchyma a dental sac saccus dentalis, which near basis of dental embryo meets
with a dental papilla, is formed.
Both the embryos of teeth and fabrics circumferential they change in the
second stage. There is stratification of homogeneous mews of enamel organ on
separate layers. Pulp appears in a center, and on periphery is layer of internal
enamel mews which give beginning of ameloblasts, that form enamel. Part of
mews of pulp, which adjoins to the layer of ameloblasts, makes the
intermediate layer of enamel organ.
At the same time there is the process of differentiation of dental papilla. It is
multiplied in sizes and is grown in deeper in an enamel organ. Vessels and
nervous fibres fit for a papilla. On the 4th month of embryo development of
neck of enamel organs germinate by a mesenchyma and resolve. Dental
embryos hereupon move away from a dental plate which also germinates by a
mesenchyma and loses connection with the epithelium of oral cavity.
It is saved and is grown back departments and free edges of dental plates which
in future grow into the singed organs of the second teeth. Round dental embryos in
the mesenchyma of jaws appear and grow bones cross-beams which form the walls
of dental teeth ridges.
In the third stage of odontogeny, which begins from the end of 4th month of
embryo period, there is the histogenesis of fabrics, a dentine, enamel and
endodontium, appears.
(See a fig. 3)
Mineralization of fabrics begins at the end of 5th month. Complete Mineralization
does not take place, and there is the layer of don’t calcify dentine in the inside of
tooth.
Development of root is carried out in a postembrionale period. The lower
department of enamel organ proliferes grows into a root epithelial vagina radicalis
epithelialis, which consists of two rows of mews — external and internal. A root
epithelial vagina deeply grows in an inferior mesenchyma and engulfs its area
which the root of tooth will appear from. Mesenchymal mews which got in an
epithelial vagina grow into odonthoblasts, which form the dentine of root of tooth.
As soon as the dentine of root will be formed, root epithelial vagina germinating by
a mesenchyma, resolves, as a result the mesenchymal mews of dental sac directly
run into the dentine of root and grow into tsementhoblasts, which form cement onthe-spot root of tooth. Part of mews, which surrounds the root of tooth, gives
beginning to development of fabrics to periodont.
Fig. 8
The second teeth appear also from dental plates. The embryos of first permanent
molar appear on the 6th month of intranatal development. The embryos of chisels,
dog-teeth appear on the 8th month of development. Dental plates grow at the same
time; on their edges the enamel organs of premolar are mortgaged. Subsequent
stages of forming similar with described for temporal teeth.
The certain degree of forming of different groups of teeth answers every term of
antenatal and postnatal period.
How the results of researches (Vinogradova T.F.) testify at the term of pregnancy
18-19 weeks (4,5 months) evidently signs of mineralization of cutting edge and
surfaces of crowns of chisels on 1/3. Also there is mineralization of mesiobuccal
knolls of first моляра.
Fig.10
Mineralization of chisels lasts in 24-25 weeks (6 months), almost fully
mineralizate cutting edge of canine; the hearths of mineralization of tongue-medial
knoll of first molars appear. The follicle of first permanent molar begins to appear.
Mineralization of chisels and dog-teeth proceeds in 26 weeks (7 months),
mineralization of medial knolls of first molars is almost closed; the follicle of
sixth tooth is multiplied.
Mineralization of incisives and canines proceeds in 32 weeks (8 months), the size
of follicle of sixth tooth is multiplied; the embryos of chisels and dog-teeth of the
second teeth appear.
In 36 weeks of pregnancy (9 months) calcified all surfaces of chisels, the process
of mineralization spreads on the approcsimal surface of first temporal molar. The
bulk of crown of first permanent molar is formed after birth of child.
- At first the rudiments of the second teeth baby and lie in general teethridges,
afterwards between them bone partition is formed. In an interval from 6 to 12
years, when baby teeth are replaced permanent, an osteoclast destroys bone
partition and root of baby tooth. Under the action of pressure, that grows in pulp of
the second teeth as a result of strengthening of synthetic activity of localisated
there fibroblasts, the crown of the tooth cuts through above the surface of alveolar
sprouts, replacing a baby tooth. The last before the fall consists only of crown and
overhead part of root. The terms of the cutting through second teeth are resulted on
a fig. 4.3, 4.4, 11.21, 11, 22, tables. 11.2.
Bones teethridges develop simultaneously with development of overhead and
lower jaws. Thus bone fabric of supramaxilla appears directly from a mesenchyma,
and the stage of formation of cartilaginous rudiment proceeds to development of
cartilage bone (cartilage of Mekkel). We will mark that a cartilaginous model is
not transformed directly in a bone, and is subject to degeneration. Round tailings of
cartilage of Mekkel from two bones rudiments the bone of lower jaw develops as a
result of direct bone genesis. The back-end of lower jaw enters into connection
with a temporal bone and with participation of fibro cartilage forms a temporal-jaw
joint. During all embryo period a lower jaw is built from two bones rudiments the
ends of which are united between itself by a fibro cartilage.
At violation of odontogenesis there are the anomalies of terms of cutting through
(including presence of teeth which were not cut through), anomalies of form and
placing of teeth, and also defect of fabrics of tooth. To the anomalies of placing
supraoccusia (overhead teeth do not achieve a closing surface), infraocclusion
(lower teeth do not achieve an occlusal surface), torsi versos (turn of tooth about
the axis), transpositions (mutual change of position of neighboring teeth), placing
of teeth belongs out of dental arc (lip-cheek, linguistic-palatal and others like that),
anomalous position (in a nasal cavity, to the gaymores bosom and others like
that), accumulation of teeth, odontoplerosis (supernumerary teeth), diminishing of
amount of teeth or their complete absence (adonti). Defects of fabrics of tooth:
fluorosis (insufficiency of fluorine and calcium), giperplasia of enamel.
(Fig. 26)
A dental embryo on an X-rays looks as light oval form. It is limited by the line of
compact bone which surrounds an embryo.
(Fig. 28)
Mineralization shows up as dense darkening. At first calcified cutting edge groups
of frontal teeth and humps of masticatory teeth.
(Fig. 15)
Afterwards the process of mineralization spreads on other parts of crown.
Forming of root of tooth comes after it.
Table 1
Сutting through temporal teeth begins on 6-8 month of life of child and is closed
to 2,5-3 years. Lower central incisives cut through the first, afterwards are their
antagonists, and then are lateral incisives. To 10-12 months all 8 incisives cut
through. First temporal molar appears in 2-3 months, after them are canine, second
molar cuts through the last (tables. 1).
Table 2
A stabilizing period comes after the period of stabilization. It is a period forming
of functional valuable temporal bite. With 6-7 years replacement of temporal bite
is begun on permanent. To it growth precedes embryos of the second teeth and
physiology resorbtion of roots of temporal teeth (tables. 2). This period lasts on the
average to 12 years and is named the period of variable bite. First permanent molar
which does not have temporal predecessors cuts through at first. Then teeth are
replaced in the same sequence in which cut through.
Table 3
The period of growth and forming of their roots comes after the cutting through
second teeth. This period lasts on the average 3-4,5 years (see tables. 3).
(Fig. 12)
After mineralization of cutting edge or masticatory surface of crown X-ray the
cavity of tooth begins to appear as a light area in the center of crown. Near basis
the cavity of tooth meets with the area of mineralization, which shows itself the
projection of area of growth. As far as growth of tooth and his calcination a sprout
area diminishes gradually. In future with appearance of bifurcation the contours of
cavity of tooth are designed and forming of roots begins.
(Fig. 14)
During forming of crown of the tooth a follicle has the rounded form. With
beginning of development of neck of tooth he begins to stretch in the direction of
root. The process of education to periodont goes along with beginning of
development of root.
(Fig. 15)
On a X-ray the unformed root evidently as two parallel strips which take
beginning near basis of crown of the tooth, where the widest part of root, then in
direction opposite to the crown, gradually narrow and end with sharp part.
A root-canal in a lower department meets with the area of light, which has the
rounded form with clear contours. This is a sprout area. This area diminishes as far
as forming of root and disappears in the stage of the unclosed apex, and the in her
place yet some time evidently extended periodontal crack.
In the process of forming of apex of root distinguish three stages: stage of the
unformed apex of root, stage of the unclosed apex of root, and stage of the fully
formed apex.
(Fig. 48)
X-ray picture of the unformed apex of root there is such: the walls of root are
located parallel, a width them diminishes gradually. A periodontal crack on all
draught has an identical width. Near an apex she meets with the area of growth.
(Fig. 49)
In the stage of the unclosed apex of wall of root have the same structure, as well
as in the stage of the unformed apex, differ from her by the greater thickness of
walls. On an X-ray expressly evidently projection of the apex opening. In the
stage of the formed apex of root of area of growth it is not, some time the extended
periodontal crack is saved, the apex opening is closed.
(Fig. 21)
Temporal teeth on an X-ray differ from permanent to those, that they less sizes,
with short roots. The roots of molars considerably to go away. Cavity of tooth and
root-canals, especially in the group of frontal teeth, considerably wider, than in
permanent.
(Fig. 20)
Since 6-7 years there is replacement of temporal bite on permanent. Physiology
resorbtion of roots of temporal teeth precedes to it. As a result of pressure of
embryo of the second teeth the area of enhanceable vascularisation appears on
surrounding fabrics. She is rich on an osteoclast and resorbtions is named.
X-ray the process of resorbtion shows up as follows. The follicles of the second
teeth have clear contours and are disposed in a direct closeness to the roots of
temporal teeth. This closeness as far as progress of resorbtion of root becomes yet
greater. Resorbtion of roots of temporal teeth concerns by correlation with the
embryos of the second teeth.
From data of Vinogradova T.F., in default of teeth-jaws anomalies children have
three as physiology resorbtion of roots of temporal teeth:
(Fig. 58)
— The first type is even resorbtion of all roots, which begins in the area of apexes
and spreads on a vertical line. Roots are resorbtions evenly. Phenomena of
resorbtion in the area of bifurcation minimum.
(Fig. 50)
— Second type — resorbtion of one root which the nearest is disposed to the
embryo of the second teeth prevails next to partial resorbtion of roots and area of
bifurcation
(Fig. 56)
— Third type — resorbtion of area of bifurcation prevails. At this type resorbtion
can be saved morphological full value of apical part of root. Area of bifurcation
often resorbtiones so that there is connection with crown pulp.
(Fig. 222)
Next to physiology pathological resorbtion of roots can develop under act of
different reasons (as a result of inflammations, new formations). Pathological
resorbtion is carried out by the multinuclear giant mews of inflammatory exsudate.
Processes of formation of bone here minimum and fall behind from resorbtion. In
this connection at pathological resorbtion of base X-ray destruction and absence
of bone fabric is a sign between the roots of temporal teeth and round them. The
process of pathological resorbtion can spread on the follicle of the second teeth,
causing premature resorbtion of bone shell of follicle and cutting through second
teeth. In the process of embryo of the second teeth violation of safety of cortical
plate is the sign of in drawing basic X-ray round him.