Lec.
2
Eruption of teeth
Assistant Professor
Aseel Haidar
Lec.2 Pedodontics Fifth stage
Dr. Aseel H. Al-Assadi
Tooth numbering system
1. Zsigmondy- palmer system
The Hungarian dentist Adolf Zsigmondy discovered this system in 1861, using a
Zsigmondy cross to record quadrants of tooth positions. Adult teeth were numbered 1 to 8,
and the child primary dentition (also called deciduous, milk or baby teeth) were depicted
with a quadrant grid using Roman numerals I, II, III, IV, V to number the teeth from the
midline. Palmer changed this to A, B, C, D, E. This makes it less confusing and less prone
to errors in interpretation.
The Palmer notation consists of a symbol (┘└ ┐┌) designating in which quadrant the
tooth is found and a number indicating the position from the midline. Adult teeth are
numbered 1 to 8, with deciduous (baby) teeth indicated by a letter A to E. Hence the left
and right maxillary central incisor would have the same number, "1", but the right one
would have the symbol, "┘", underneath it, while the left one would have, "└".
Advantages:
1) Easy to implement.
2) Easy of writing and communication.
3) Less mistakes in identifying the designated tooth.
Disadvantages:
1) Cannot be written by the computer.
2) Non-numeric symbolization.
2. Universal numbering system
This tooth numbering system was proposed by German dentist Julius Parredidt in
1882. Although it is named the "universal numbering system", it is also called the
"American system" as it is commonly used in the United States. The uppercase letters
A through T are used for primary teeth and the numbers 1 - 32 are used for permanent
teeth. The tooth designated "1" is the maxillary right third molar ("wisdom tooth") and
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the count continues along the upper teeth to the left side. Then the count begins at the
mandibular left third molar, designated number 17, and continues along the bottom teeth
to the right side. Each tooth has a unique number or letter, allowing for easier use on
keyboards. As specific numbers are employed for each tooth, it reduces the risk of
mistake. Data can also be easily entered in the computer.
Advantages –
1. Individual number for each tooth. 2. Simple
Disadvantages:
1. Difficult in remembering the tooth no.
2. Matching the specific teeth and quadrants can be confusing.
3. There is no anatomic reference in this system and so it is difficult to follow for the
beginners, and needs extra training to practice.
3. International numbering system
The Federation Dentaire Internationale (FDI) system is a two-digit
system, the first digit indicates the quadrant (1 through 4 for permanent and 5
through 8 for deciduous teeth) and the second digit indicates the tooth type (1
through 8 or 1 through 5). It is very simple, accurate, it is easy to memorize in
the visual and cognitive sense, it is user friendly, and prevents errors in
differentiating left and right, upper and lower arches, and tooth type. However,
in the case of deciduous teeth, there can be confusion and it is difficult to
memorize. For specialists other than paedodontists, it can be difficult to
understand or to define teeth, as in the case for example of 64, 85.
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For primary teeth For permanent teeth
**This system makes the visual, cognitive and computer sense.
Advantages:
Easy to remember and understand
Unique number for each tooth
Verbal communication is possible
Compatible with computer keyboard
Hence most accepted.
Sequence of eruption
For primary teeth: ABDCE
ABDCE
For permanent teeth: 61245378
61234578
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VARIATIONS IN SEQUENCE OF ERUPTION
The mandibular first permanent molars are often the first permanent teeth to erupt.
The mandibular central incisors quickly follow them. Then lateral incisor, canine, first
premolar, second premolar, and second molar (the most common sequence of eruption of
mandibular permanent teeth ), while the most common sequence for the eruption of the
maxillary permanent teeth is first molar, central incisor, lateral incisor, first premolar,
second premolar, canine, and second molar.
It is desirable that the mandibular canine erupt before the first and second premolars.
This sequence aids in: 1. Maintaining adequate arch length and 2. Preventing lingual
tipping of the incisors, which not only causes a loss of arch length but also allows an
increased overbite to develop. An abnormal lip musculature or an oral habit that causes a
greater force on the mandibular incisors than can be compensated for by the tongue allows
the anterior segment to collapse. For this reason, use of a passive lingual arch appliance is
often indicated when the primary canines have been lost prematurely or when the sequence
of eruption is undesirable.
A deficiency in arch length can occur if the mandibular second permanent molar
develops and erupts before the second premolar. Eruption of the second permanent molar
first encourages mesial migration or tipping of the first permanent molar and encroachment
on the space needed for the second premolar.
In the maxillary arch, the first premolar ideally should erupt before the second
premolar, and the canine should follow them. The untimely loss of primary molars in the
maxillary arch, which allows the first permanent molar to drift and tip mesially, results in
the permanent canine is being blocked out of the arch, usually to the labial side. The
position of the developing second permanent molar in the maxillary arch and its
relationship to the first permanent molar should be given special attention. Its eruption
before the premolars and canine can cause a loss of arch length, just as in the mandibular
arch. The eruption of the maxillary canine is often delayed because of an abnormal position
or deviations in the eruption path.
LINGUAL ERUPTION of MANDIBULAR
PERMANENT INCISORS
The primary teeth may have undergone extensive root resorption and may be held
only by soft tissues. In other instances, the roots may not have undergone normal resorption
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and the teeth remain solidly in place. It is common for mandibular permanent incisors to
erupt lingually, and this pattern should be considered essentially normal.
The tongue and continued alveolar growth seem to play important roles in influencing
the permanent incisors into a more normal position with time. Although there may be
insufficient room in the arch for the newly erupted permanent tooth, its position will
improve over several months. In some cases there is justification for removal of the
corresponding primary tooth. Extraction of other primary teeth in the area is not
recommended, however, because it will only temporarily relieve the crowding and may
even contribute to the development of a more severe arch length inadequacy.
Even when mandibular permanent incisors erupt uneventfully, they often appear
rotated and staggered in position. The molding action of the tongue and the lips improves
their relationship within a few months.
TEETHING AND DIFFICULT ERUPTION
1) Increase in salivation, the child will want to put the hand and fingers into the
mouth—these observations may be the only indication that the teeth will soon erupt.
2) The young child may become restless and fretful during the time of eruption of the
primary teeth. He may loss his appetite.
3) In the past, many conditions, including croup, diarrhea, fever, convulsions, primary
herpetic gingivostomatitis, and even death have been incorrectly attributed to
eruption. Because the eruption of teeth is a normal physiologic process, the
association with fever and systemic disturbances is not justified. A fever or
respiratory tract infection during this time should be considered coincidental to the
eruption process rather than related to it.
4) Inflammation of the gingival tissues before complete emergence of the crown may
cause a temporary painful condition that subsides within a few days. The surgical
removal of the tissue covering the tooth to facilitate eruption is not indicated. If the
child is having extreme difficulty and to relief pain use:
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a) A nonirritating topical anesthetic may bring temporary relief. The parent can
apply the anesthetic to the affected tissue over the erupting tooth three or four
times a day.
b) Several low-dose products specifically formulated for infants are available
without prescription. Caution must be exercised, however, when one is
prescribing topical anesthetics, especially for infants, because systemic
absorption of the anesthetic agent is rapid, and toxic doses can occur if the
product is misused. The parent must clearly understand the importance of using
the drug only as directed.
c) The eruption process may be hastened if the child is allowed to chew on a piece
of toast or a clean teething object.
Interval of rest
It is the largest time between eruptions of two successive permanent teeth
2 2 and 4 4 1.5 years.
ERUPTION HEMATOMA
(ERUPTION CYST)
An eruption hematoma is a bluish-
purple elevated area of tissue occasionally develops a
few weeks before the eruption of a primary or permanent
tooth. It may result from trauma to the area during function
and then hemorrhage in the follicle of an erupted tooth and it will subside after eruption
after breakage of the soft tissue by the tooth. The blood-filled cyst is most frequently seen
in the primary second molar or the first permanent molar region (6 and E). Because the
condition is almost always self-limiting, treatment of an eruption hematoma is rarely
necessary. However, surgical uncovering of the crown may occasionally be justified. When
the parents discover an eruption hematoma, they may fear that the child has a serious
disease such as a malignant tumor. The dentist must be understanding and sensitive to their
anxiety while reassuring them that the lesion is not serious.
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ERUPTION SEQUESTRUM
The eruption sequestrum is occasionally seen in children
at the time of the eruption of the first permanent molar (6). Clinically
it is appear as a tiny spicule of nonviable bone overlying the crown
of an erupting permanent molar just before or immediately after the
emergence of the tips of the cusps through the oral mucosa. It is
composed of dentin and cementum as well as a cementum-like
material formed within the follicle.
Eruption sequestra are usually of little or no clinical
significance. It is probable that some of these sequestra
spontaneously resolve without noticeable symptoms. However,
after an eruption sequestrum has surfaced through the mucosa, it
may easily be removed if it is causing local irritation. The base of the sequestrum is often
still well embedded in gingival tissue when it is discovered, and application of a topical
anesthetic or infiltration of a few drops of a local anesthetic may be necessary to avoid
discomfort during removal.
ECTOPIC ERUPTION
A variety of local factors may influence a tooth to erupt or try to erupt in an
abnormal position such as arch length inadequacy and tooth mass redundancy.
Occasionally this condition may be so severe that actual transposition of teeth takes
place. First permanent molars may be positioned too far mesially in their eruption path,
with resultant ectopic resorption of the distal root of the second primary molar.
There are two types of ectopic eruption— reversible and irreversible. In the
reversible type, the molar frees itself from the ectopic position and erupts into normal
alignment, with the second primary molar remaining in position while in the irreversible
type, the maxillary first molar remains unerupted and in contact with the cervical root area
of the second primary molar. By the ages of 7 and 8 years, any ectopic eruption of a
permanent first molar should be considered irreversibly locked.
The ectopic molar often occurred in more than one
quadrant and was most often observed in the maxilla.
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Irreversible ectopic molars that remain locked, if untreated, can lead to premature
loss of the primary second molar with a resultant decrease in
quadrant arch length, asymmetric shifting of the upper first
molar toward Class II positioning, and supraeruption of the
opposing molar with distortion of the lower curve of Spee and
potential occlusal interference. Early assessment with
intraoral or panoramic films approximating the timing of first
permanent molar eruption is thus critical to identification of
the problem and provides an opportunity to intercept potential sequelae. If the problem is
detected at 5 to 6 years of age, an observation approach of “watchful waiting” with
appropriate monitoring may be indicated, given the two-thirds potential for self-correction.
With self-correction being unlikely as the child approaches 7 years of age, continued
“locking” of the first molar with advanced resorption of the primary second molar usually
warrants intervention. Another timing clue is that when the opposing molar reaches the
level of the lower occlusal plane, intervention is indicated to establish proper vertical
control and prevent supraeruption.
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