This document discusses delayed tooth eruption (DTE). It defines various types of DTE and outlines the normal process of tooth eruption. It identifies several potential local and systemic causes of DTE, including supernumerary teeth, ankylosed deciduous teeth, premature loss of deciduous teeth, arch length deficiencies, nutritional deficiencies, endocrine disorders, and genetic syndromes. The document also provides details on the typical chronology and sequence of primary and permanent tooth eruption.

1. Safa Basiouny
Delayed Eruption
Delayed Eruption
Collected by
Safa Basiouny Mahmoud Alawy
MSc, PhD Orthodontics
Lecturer of Orthodontics, Faculty of Dentistry,
Tanta University

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Delayed Eruption
Contents
1-Definitions And Terminology.
2-Movements leading to tooth eruption (Phases of
tooth eruption).
3-Choronology of tooth eruption.
4- Etiology of delayed tooth eruption.
5-Diagnosis and clinical implications.
6-Therapeutic consideration for patient with
DTE(Management).
1- Definitions And Terminology:

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Eruption : developmental process responsible for moving a tooth
from its crypt position through the alveolar process into the oral
cavity to its final position of occlusion with its antagonist. It is a
dynamic process that encompasses completion of root development
,establishment of the periodontium , and maintenance of a
functional occlusion.
Emergence: the moment of appearance of any part of the cusp or
crown through the gingiva. Emergence is synonymous with moment
of eruption, which is often used as a clinical marker for eruption.
Impacted teeth : those prevented from erupting by some physical
barrier in their path. Common factors in the etiology of impacted
teeth include lack of space due to crowding of the dental arches or
premature loss of deciduous teeth. Frequently, rotation or other
positional deviation of tooth buds results in teeth that are "aimed" in
the wrong direction, leading to impaction.
Primary retention: term used to describe the cessation of eruption
of a normally placed and developed tooth germ before emergence,
for which no physical barrier can be identified.
Pseudoanodontia: is a descriptive term that indicates clinical but
not radiographic absence of teeth that should normally be present in
the oral cavity for the patient’s dental and chronologic age. In these
cases radiographic examination discloses the teeth in the jaws.
These persons might have retained their deciduous teeth; more
commonly, the deciduous teeth have been shed, but the permanent
ones failed to erupt.
Primary or idiopathic failure of eruption: is a condition described
by Profitt and Vig whereby non ankylosed teeth fail to erupt fully or
partially because of malfunction of the eruption mechanism.
This occurs even though there seems to be no barrier to eruption,
and the phenomenon is considered to be due to a primary defect in
the eruptive process.
Embedded teeth: are teeth with no obvious physical obstruction in
their path; they remain unerupted usually because of a lack of
eruptive force.
Submerged teeth and inclusion/reinclusion of teeth: refer to a
clinical condition whereby, after eruption, teeth become ankylosed
and lose their ability to maintain the continuous eruptive potential as

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the jaws grow. Such teeth then seem to lose contact with their
antagonists and might eventually be more or less “reincluded” in the
oral tissues. This condition should not be confused with chronologic
delayed eruption, because the eruption was normal according to both
chronologic and biologic parameters (root formation), but the
process was halted.
Paradoxical eruption: simply has been used to represent abnormal
patterns of eruption and can encompass many of the above
conditions.
Delayed tooth eruption (DTE): is the emergence of a tooth into the
oral cavity at a time that deviates significantly from norm
established for different races, ethnicities, and sexes.
chronologic DTE: the eruption time that is greater than 2 SDs from
the mean expected eruption time for a specific tooth (chronologic
norm of eruption).
Normal biologic eruption time: tooth eruption that occurs when the
dental root is approximately 2/3 its final length.
Delayed biologic eruption: tooth eruption that has not occurred
despite the formation of 2/3 or more of the dental root. Thus, if a
patient has chronologic delayed eruption, he or she might simply be
of a dental age that does not fit the norms (root length less than 2/3).
2-Movements leading to tooth eruption (Phases of tooth
eruption):
For teeth to become functional, considerable movement is required to
bring them into the occlusal plane. The tooth eruption is a complex and
tightly regulated process which is divided into five stages:
o preeruptive movements
o intraosseous stage
o mucosal penetration
o preocclusal
o postocclusal stages.
Preeruptive movements
-Preparatory to the eruptive phase.

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-Occur during crown formation.
-Made by the deciduous and permanent tooth germs within tissues of the
jaw before they begin to erupt.
these movements relate to the adjustment that each crown make in
relation to its neighbor and to the jaws as they increase in width, high
and length.
Active eruption movements
-Occur when root formation begins and therefore it was believed that
eruptive force comes from periodontal ligament.
-For active tooth eruption to begin
-Eruption pathway by osteoclasts in alveolar bone must be formed. In
succedeaneous dentition, this pathway follows the gubernacular canal (a
strand of fibrous tissue containing remnants of dental lamina above each
succedeaneous tooth maintaining its connection with lamina propria of
the oral mucous membrane)
i.e. bone resorption widens this canal to allow the crown to move
through it and exit the alveolar bone.
-It was shown that dental follicle (DF) plays major role during
intraosseous stage of eruption as teeth didn’t erupt if the DF had been
removed. Osteoclasts which create eruption pathway are formed from
mononuclear cells which in turn are recruited to the DF by chemokines.
-During intraosseous stage there is a coordinated translocation of the
tooth into resorbed space, bone apposition at the DF fundus and
simultaneous root elongation.
- Formation of the eruption pathway is completed soon after the cusps
reach the alveolar crest and at this point the rate of eruption accelerates.
-The outer enamel epithelium of the tooth bud proliferates and fuses with
oral epithelium creating the junctional epithelium on the tooth surface.
-Erupting tooth penetrates mucosa and preeoclusal eruption stage begins.
As the root grows and bone forms at the base of the crypt, tooth reaches

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functional occlusion plane.
The tooth also make Posteruptive movements after it has reached its
functional position in the occlusal plane.
Posteruptive tooth movements are those made by the tooth maintaining its
position in occlusion while the jaws continue to grow and compensate for
occlusal and proximal tooth wear.It includes three categories:
(1) movements to accommodate the growing jaws
(2) those to compensate for continued occlusal wear
(3) those to accommodate interproximal wear.
Accommodation of Growth:
Accommodating the growth of the jaws are completed toward the end of the
second decade, when jaw growth ceases. Readjustment of the position of the
tooth socket is achieved by the formation of new bone at the alveolar crest and
on the socket floor to keep pace with the increasing height of the jaws. The
apices of the teeth move 2 to 3 mm away from the inferior dental canal.
Compensation for Occlusal Wear:
This is achieved by the continued cementum deposition around the apex of the
tooth; however, the deposition of cementum in this location occurs only after
the tooth has moved axially.
Accomodation for Interproximal Wear:
-Wear also occurs at the contact points between teeth, on their proximal
surfaces and its extent can be considerable (more than 7 mm in the mandible).
Mesial or approximal drifting compensates for the interproximal wear.
-This is important in the practice of Orthodontics because the maintenance of
tooth position after treatment depends on the extent of such drift.

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Mesial drift is multifactorial and include:
(A) anterior component of occlusal force
(B) contraction of the transseptal ligament between teeth
(C) soft tissue pressure.
A-Anterior component of occlusal force
-When the roots of the permanent dentition are examines it was noticed that
the degree of root curvature increases towards the back of the mouth i.e. the
distal inclination of the teeth increases toward the end of the series.
-Therefore, when the permanent teeth come into occlusion they exert upon
each other an equal and opposite force. As aresult of their long axial
inclination, this force will be divided into vertical and horizontal component of
force which is transmitted from tooth to tooth through the approximal contact.
-The anterior component of force on one side of the arch will cancel out that of
the other side in the midline provided that there is an intact dental arch.
✓ If the interproximal contacts are broken by loss of a tooth those behind
the gap tend to drift forward while those in front will lack forward
development.
✓ -The deciduous teeth are more or less vertical in the alveolus so that
when they occlude there is little dislodging force.
B-Contraction of the Transseptal Ligament
-The Peridontal ligament plays an important role in maintaining tooth position.
Transseptal fibers draw neighboring teeth together and maintain them in
contact; they are also capable of adaptation. For example, relapse of
orthodontically removed teeth is reduced if a gingivectomy removing the
transseptal ligament is performed( circumfrencial supra crestal fibrotomy).

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-Grinding away of proximal contacts provides room for a tooth to move, after
which teeth move to reestablish contact.
C-Soft Tissue Pressures
-The pressures generated by the cheeks and tongue may push teeth mesially.
Soft tissue pressure does influence tooth position even if it does not cause
tooth movement. It does not play a major role in creating mesial drift.

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3-Choronology of tooth eruption:
❖ Deciduous dentition:
The sequence of eruption of the primary teeth are:
A:deciduous central incisor, B:deciduous lateral incisor, D:deciduous first
molar, C:deciduous canine, E:second deciduous molar.
The usual order and average time of deciduous teeth eruption are:
o Lower A at 6 months.
o Upper A at 9 months.
o Upper B at 12 months.
o Lower B at 12 months.
o Upper and lower D at 18 months.
o Upper and lower C at 2 years.
o Upper and lower D at 2.5 years.
✓ The age of eruption varies greatly and can be modified by genetic, local
and systemic factors.
✓ Variation in the time of eruption of the same tooth on the two sides of
jaw may happen.
✓ Sixty % of children exhibit disturbances such as fever, diarrhea, and
irritability for short time before tooth eruption and, resolve after tooth
emergence.
❖ Permanent dentition:
The usual order of eruption of permanent teeth in each arch are:
1, 2, 4, 5, 3, 7, in the upper arch.
1, 2, 3, 4, 5, 7, in the lower arch.

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Sequence of eruption
6 y. First permanent molars(the lower ahead of the upper)
6.5 y Lower central incisors
7 y Upper central incisor and lower lateral incisors
8 y Upper lateral incisors
9 y Lower canines
10 y Upper first& second premolars, lower first premolar
11 y Upper canines& lower second premolar
12 y Second molars (the lower ahead of the upper)
18 y Third molars

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4-Etiology of delayed tooth eruption:
Retarded eruption can be caused by the following:
A- Local B- Systemic C- Genetic disorders
1-Supernumerary
2-Ectopic eruption
3-Premature ext of deciduous
4-Retained deciduous
5-Ankylosis of deciduous
6-Injuries to primary teeth
dilaceration of permanent root
7-Localpathologt-cyst or tumor
8-Mucosal barrier- scar tissue
9-Gingival fibromatosis
10-Arch length deficiency
1-Malnutrition
2-Preterm birth
3-Vit D-resistant rickets
4-Endocrine disorders
Hypothyroidism
Hypopituatrism
Hypoparathyroidism
5-oral clefts
6- Long-term chemotherapy
7-Drugs-phenytoin
8- X radiation
9-Anemia
10-Familial/Inherited
11-Idiopathic
1-Amelogenesis imperfecta
2-Down syndrome
3-Cleidocranial dysplasia
4-Gardner syndrome
5-Ectodermal dysplasia
6-Cherubism
7-Gorlin syndrome
8-Osteogenesis imperfecta
A-Local factors:
1-Supernumerary teeth:
Definition: A supernumerary tooth is one that is additional to the normal series
and can be found in almost any region of the dental arch
Causes: 1-Dichotomy of the tooth bud.
2-Hyperactivity of the dental lamina.

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3-Heredity may also play a role in the occurrence of this anomaly.
Classification:
A-Single:1-Conical…as mesiodense between central incisors.
2-Supplemental…aduplication of teeth in the normal
series. The most common is the permanent max lateral
3-Tuberculate…possess more than one cusp or tubercle.
4-Odontoma…hamartomatous malformation rather than
neoplasm.
B-Multiple:
1-Non syndrome.
2-Syndrome associated…Cleidocranial & Gardner.
Complications: Supernumerary teeth can cause crowding, displacement, rotation,
impaction, or delayed eruption of the associated teeth.
Supernumerary preventing eruption of the UR1
2-Eectopic eruption:
Definition: Abnormal eruptive position of a tooth.
Causes: 1-Delayed exfoliation of dec teeth.
2-Presence of supernumerary teeth, cysts and other infections.
3-Prolonged retention or premature ext of dec teeth.
4-Misplaced tooth germs.
3-Premature loss of deciduous teeth:
This can be explained by the abnormal changes that might occur in the connective
tissue overlying the permanent tooth and the formation of thick, fibrous gingiva.
Crowding of maxillary second premolars as a result of
early loss of the second deciduous molars. The UL5
remains impacted in the palate whilst the UR5 has
erupted palatally

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4-Retained deciduous teeth:
Causes: 1-Absence of permanent successor.
2-Malposition of the erupting permanent teeth.
3-Impaction of permanent teeth.
4-Ankylosis with the alveolar bone.
Retained deciduous incisors.
The permanent incisors have
failed to resorb their deciduous
predecessors and erupted
palatally (upper panel) and
lingually (lower panel).
5-Ankylosis:
Definition: The fusion of the cementum or dentin with the alveolar bone. It is the
most common local cause of delayed deciduous tooth exfoliation.
Causes: l -Genetic predisposition
2- Failure of normal resorption by the permanent successor
3- Congenital absence of the permanent successor
4- Trauma
5- Infection.
Incidence: Ankylosis occurs commonly in the deciduous dentition, usually
affecting the molars. The mandible is more commonly affected than the maxilla.
Ankylosed teeth will remain stationary while adjacent teeth continue to erupt
through continued deposition of alveolar bone, giving the clinical impression of
infraocclusion.

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Infraocclusion of the ULE
6- Injuries to deciduous teeth:
Traumatic injuries can lead to:
1-ectopic eruption
2-disruption in normal odontogenesis in the form of dilacerations
3- physical displacement of the permanent germ.
4-In some instances, the traumatized deciduous incisor might become ankylosed
or delayed in its root resorption. This also leads to the over retention of the
deciduous tooth and disruption in the eruption of its successor.
7-Local pathology:
Odontomas, cysts and other tumors (in both the deciduous and permanent
dentitions) have also been occasionally reported to be responsible for DTE.
Affected teeth exhibit a delay or total failure in eruption. Their shapes are
markedly altered, generally very irregular, often with evidence of defective
mineralization.
Incidence: Central incisors, lateral incisors, and canines are the most frequently
affected teeth, in either the maxillary or mandibular arch, and deciduous and
permanent teeth can be affected.
8-Mucosal barrier:
Any failure of the follicle of an erupting tooth to unite with the mucosa will entail
a delay in the breakdown of the mucosa and constitute a barrier to emergence.
9-Gingival hyperplasia :
Definition: an abundance of dense connective tissue or acellular collagen that
can be an impediment to tooth eruption
Causes: (hormonal or hereditary causes, vitamin C deficiency, drugs such as
phenytoin.

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10-Arch-length deficiency:
Definition: A negative difference between the space available in the dental arch
and the space required to align the teeth. It is often mentioned as an etiologic
factor for crowding and impactions.
Crowding: discrepancy between tooth size and jaw size resulting in irregularities
and malalignment of teeth.
It can be classified into: mild, moderate, or severe.
There are two ways to measure crowding:
According to the broken contact: Mild = 1-2 broken contact
Moderate = 2-5 broken contact
Severe = more than 5 broken contact
According to measurement by mm’s:
Mild = 1-4 lack of space
Moderate = 5-8mm lack of space
Severe = 8mm
(Model analysis):
A-alignment(crowding):space analysis
It is important to quantify the amount of crowding within the arches because
treatment varies, depending on severity of crowding. Space analysis, using the
dental casts to measure the size of the teeth versus the space available for them is
required for this purpose:
1- Mixed dentition analysis:
The purpose of a mixed dentition analysis is to evaluate the amount of space
available in the arch for succeeding permanent teeth and necessary occlusal
adjustments. Many methods of mixed dentitions analysis have been suggested;
however, all fall into two strategic categories:
1. Those in which the sizes of the unerupted cuspids and premolars are estimated
from measurements of the radiographic image, and
2. Those in which the sizes of the cuspids and premolars are derived from
knowledge of the sizes of permanent teeth already erupted in the mouth.

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A-Nance analysis:
Procedure:
1.The width of the erupted 4 mandibular permanent incisors is first measured
(actual width should be determined rather than the space the incisors occupy in the
arch).
2.The individual measurements are recorded.
3.The width of the un erupted mandibular canines and first and second premolars
on the radiographs should be measured next. The estimated measurements are then
recorded. If one of the premolars is rotated the measurements of the corresponding
tooth on the opposite side of the mouth may be used. This will give indication of
the space needed to accommodate all the permanent teeth anterior to the first
permanent molars.
4.Next step is to determine the amount of space available for the permanent teeth :
A piece of soft brass wire contoured to arch surface of the first permanent molar to
the opposite side. The wire should pass along the buccal cusps of the posterior
teeth & the incisal edge of the anterior teeth. From this measurement must be
subtracted 3.4mm, the amount by which the arch length may be expected to
decrease as a result of the mesial drifting of the first permanent molars unless the
leeway space is being held.
✓ It is often difficult to obtain an un-distorted view of the canines and this
reduce the accuracy. With any type of radiograph, it is necessary to
compensate for enlargement of the radiographic image, this can be done by
measuring an object that can be seen both in the radiograph and on the
casts(usually a primary molar tooth).
✓ A simple proportional relation can then be set up:
True width of primary molar True width of unerupted premolar
=
Apparent width of primary molar Apparent width of unerupted premolar
B-Moyer's mixed dentition analysis:
-Estimation from proportionality tables: those in which the sizes of the cuspids
&premolars are derived from knowledge of the size of permanent teeth already
erupted in the mouth.
-He measured the mand incisors then predict the size of the upper and lower
canine and premolars by the aid of the probability chart.
-The mandibular incisors have been chosen for measuring, since they erupt into
the mouth early in the mixed dentition. The maxillary incisors are not used in any

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of the predictive procedures, since they show too much variability in size, and
their correlations with other groups of teeth are of lower predictive value.
The following procedure has been suggested by Moyer todetermine the space
available for teeth in the mandibular arch:
1. Measure with the tooth-measuring gauge or a pointed Boley's gauge, the
greatest mesiodistal width of each of the four mandibular incisors.
2. Determine the amount of space needed for alignment of the incisors:
Set the Boley's gauge to a value equal to the sum of the widths of the right central
incisor and right lateral incisor. Place one point of the gauge at the midline of the
alveolar crest between the central incisors and let the other part lie along the line
of the dental arch on the right side. Mark on the tooth or the cast the precise point
where the distal surface of the lateral incisor will be when it has been aligned.
Repeat this process for the left side of the arch.
3. Compute the amount of space available after incisor alignment. To do this,
measure the distance from a point marked in the line of the arch to the mesial
surface of the first permanent molar. This distance is the space available for
the cuspid and two bicuspids and for any necessary molar adjustment after the
incisors have been aligned. Record the data for both sides on the mixed dentition
analysis form.
4. Predict the size of the combined widths of the mandibular cuspid and bicuspids.
Prediction of the combined widths of cuspid, first bicuspid, and second bicuspid is
done by use of probability charts.
5.compute the amount of space remaining in the arch for first permanent molar
adjustment.
6.the estimated canine and premolar size value is subtracted from the measured
space. It must be assumed that first permanent molar will move mesially on each
side unless restrained with a holding appliance.
This analysis can be completed in the mouth aswell as on the casts,and it may be
used for both archs
He recommended the use of 75 % level probability for prediction. A higher
prediction value is used if the lower 2nd
premolar has 2 lingual cusps.
Note: the mand incisors used for prediction of both the mandibular and maxillary
cuspids and bicuspids widths.
C-Tanaka and Johnson analysis:
This method is a variation of Moyer's analysis except that a table is not needed.
Procedure:
1.the sum of the widths of the mandibular permanent incisors is measured and
divided by 2.

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2.for the lower arch, add 10.5mm to estimate the mandibular canine and premolar
for one quadrant.
3.for the upper arch, add 11mm to estimate the maxillary canine and premolar for
one quadrant.
2- permanent dentition analysis:
Carey's analysis:
This analysis is usually done in the lower arch. The same analysis when carried
out in the upper arch is called as arch perimeter analysis.
Procedure:
1. The arch length is measured anterior to the first permanent molar using a soft
brass wire. The wire is placed touching the mesial aspect of lower first permanent
molar, then passed along the buccal cusps of premolars, incisal edges of the
anteriors and finally continued the same way up to the mesial of the first molar of
the contralateral side.
2.The distance between mesial contact points of the first permanent molars
recorded from the straightened wire is the amount of space available in the dental
arch
3.The mesiodistal width of teeth anterior to the first molars are measured and
summed up as the total tooth material(space required)
4.The difference between the arch length and the actual measured tooth material
gives the discrepancy(negative value = space deficiency).
B-Tooth size analysis:
(Bolton analysis):
-The determination of tooth size ratios between the maxillary and mandibular teeth
is essential for proper orthodontic diagnosis, treatment planning and result
prediction.
-The desirable ratio is necessary to attain an optimum interarch relationship. If the
analysis indicates a marked deviation, it can give an insight into the required
pattern of treatment and extraction. The Bolton procedure is used in this case to
determine the overall ratios. It is as follows:
1. The sum of the mesiodistal diameter of the 12 maxillary teeth and the sum of
the mesiodistal diameter of the 12 mandibular teeth including the first molar is
calculated, this is called the overall ratio:
If the overall ratio is less than 91.3%, then the maxillary tooth material is
excessive.

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2.We can use the same equation for the anterior 6 teeth only from canine to
canine. This called the Anterior Ratio:
If the ratio is less than 77.2%, the maxillary teeth are excessive.
Management of ALD:
Severe problems Normal dental development Moderate problems
Expansion or
Extraction
Expansion or
extraction
Space analysis
Localized space deficiency due to
early loss of primary canine or molar
3mm or less
Localized moderate to severe
crowding>3mm
4-5mm or less space deficiency
(generalized moderate crowding)
>4-5mm
Severe crowding>10mm
Space regaining
Arch expansion
Planning for
Serial extraction
Treatment in bold should be accomplished early.
1-localized space loss (3mm or less): space regaining
It can be created by drift of permanent incisor or molars after premature extraction
of primary canines or molars respectively.
Lost space can be regained by repositioning the teeth that have drift, and then a
space maintained is placed until the succedaneous teeth have erupted.
A-Loss of e prematurely:
Maxillary space regaining:
1. A removable appliance with Adam's clasp and incorporating a helical finger
spring adjacent to the tooth to be moved or expansion screw

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2. For unilateral spacer gaining with bodily movement of the permanent 1st
molar: a fixed appliance is preferred. The anchorage provided by the
remaining teeth can support the force generated by a coil spring on a
segmental arch wire with good success, but to be effective, the support of a
modified Nance arch usually is needed.
3. In bilateral space loss: extra oral force via a face bow to the molar is
effective.
Mandibular space regainer:
1. For unilateral space regaining: the best choice is a fixed appliance. A
lingual arch can be used to support the tooth movement and provide
anchorage when used in a segmental archwire and coil spring.
2. In bilateral space loss:
a-An active lingual arch can be used but a
significant forward displacement of the incisors
must be expected
Expansion can be accomplished by slight opening
the loops located mesial to the banded molars
b-lip bumper:
it is a labial appliance fitted to the tubes on the
molar bands.
It passes against the lips which creates a distal force
to tip the molars posteriorly.
It alters the equiliprium forces against the incisors
( the labial musculatures are shielded from the lower
incisors) which lead to forward movements of the
lower incisors by the force of the tongue.
B- unilateral loss of C prematurely:
treatment is needed to avoid midline shift
• Mesial drift of posterior teeth is rare.
• Incisors drift distally, reducing the available arch length and increase the
crowding……midline will shift in this direction
Treatment:
Either:
1. remove the contralateral canine or
2. maintain the position of the lateral incisor by using a lingual holding
arch with a spur.
c- bilateral loss of deciduous canine:

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1. an active lingual arch for expansion, a passive lingual arch for
maintenance.
2. Space analysis may reveal that the crowding associated ectopic eruption
is so severe that complex treatment involving alignment of the teeth with
fixed appliance, premolar extraction, or both are required.
✓ Note: studies of children with normal occlusion indicate that when they go
through the transition from the primary to the mixed dentition, up to 2mm
of incisor crowding may resolve spontaneously without treatment.
3- Localized moderate to severe crowding>3mm:
This is most likely the result of severe space loss or ectopic eruption and
typically prevents eruption of asuccedaneous tooth.
Treatment:
1.in the posterior quadrants: extract the impacted tooth and close the space .
this generally take less time than regaining space and encouraging the eruption
of the impacted tooth.
2.in the anterior portion of the arch:
The most common problem is shift of the mandibular dental midline tooth
movement is more often used to solve the problem than single tooth extraction.
a. If the midline has moved and the space is inadequate a supportive
lingual arch to maintain molar symmetry and control, bonding of the
incisors, and correction of the midline with coil spring.
b. In some cases, disking or extraction of a primary canine or molar will be
required to provide the necessary room to reestablish the midlines and
space. A lingual arch can then be used as a retainer to maintain the
correction.
c. If both primary canines are lost the permanent incisors tip lingually , which
reduce the arch circumference and increase the apparent crowding an
active lingual arch for expansion may be indicated. In some children, space
analysis will reveal that the crowding associated with ectopic eruption of
lateral incisors is more severe and fixed appliances are needed to expand the
arch.
3-Generalized moderate crowding:
• Generalized arch length discrepancy up to 4mm.
• No prematurely missing in teeth can be expected to have moderate
crowded incisors.

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• If the c have been exfoliated naturally or by the dentist the canine
spaces partially closed.
✓ Note: avoid lingual drifting of the incisor further increasing the space
discrepancy.
Treatment:
Unless the incisors are severely protrusive, the long-term plan will be
generalized expansion of the arch to align the teeth
o gentle expansion of the arch by tipping the molars slightly distally and
the incisors slightly forward by an adjustable lingual arch in the
mandible or face bow with extra oral force in the maxilla.
4-space discrepancy of 5mm or more:
• The larger the space discrepancy, the greater the chance that extraction of
some teeth will be necessary to align the remaining ones.
• Two symptoms:
1.ectopic eruption of lateral incisors
2.Severe crowding and irregularity of the erupting permanent incisors
After definitive analysis of the profile and incisor position, the decision must be
made either to expand the narrow v-shaped arch, after considering growth
potential, or extract permanent teeth.
5-Serial extraction(10mm discrepancy):
Definition: sequential removal of deciduous teeth to facilitate the eruption of the
permanent teeth which often, but not always, results in the extraction of the 4
premolar teeth.
Indications:
In class I malocclusion, crowding lower anterior teeth, exfoliation of canines due
to increase in dimension of lower anterior teeth, normal overbite and no skeletal
disproportions.
Contra indications:
1.classII or class III malocclusion
2.bi-alveolar retrusion…dished in face
3.bi alveolar protrusion, because maximum retraction of the incisors is
desirable.so, fixed appliance with maximum anchorage mechanics is indicated.

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4.narrow trapped maxilla, the arch should be expanded firstly.
Generally it consists of 4 steps:
1.extraction of B:as the permanent central incisor erupt
2. extraction of C:as the permanent lateral incisor erupt
3. extraction of D:12 months before their normal exfoliation
4. extraction of the 1st
premolars before eruption of the permanent canines.

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B-Systemic & genetic disorders:
• Malnutrition:
Delayed eruption is often reported in patients who are deficient in some essential
nutrient. The high metabolic demand on the growing tissues might influence the
eruptive process
• Preterm birth:
-According to World Health Organization (WHO) preterm birth is defined as birth
occurring before 37 weeks of gestation or if the birth weight is below 2500 g.
 Cause of DTE: Retardation of dental growth and development.
• Vit D-resistant rickets:
Vit D deficiency results in:
1. Interference with bone growth.
2. Rickets (bowlegs- forward projection at the breast bone (pigeon
chest) – scoliosis or kyphosis).
3. Delayed closure of fontanels.
4. Disturbed calcification of teeth.
5. Slight retardation of eruption of deciduous and permanent teeth.
6. Early loss of deciduous teeth due to caries.
7. The teeth are irregularly arranged following rickets.
8. The maxilla is narrow and the palate is high.
9. The mandible is shortened.
 Causes of DTE: Interference with bone growth and early loss of deciduous
teeth.
• Endocrine disorders:
Hypothyroidism
Hypopituatrism
Hypoparathyroidism
Disturbance of the endocrine glands usually has a profound effect on the entire
body, including the dentition.
Hypothyroidism (cretinism) is characterized by:-
1. Stunting of growth, infantile skeletal proportions and naso-orbital
configurations (thick neck, large face and head, thick lips, large
protruding tongue and short extremities).
2. Delay of calcification of the tooth buds.
3. Delayed eruption patterns and periodontal disturbances.

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4. Prolonged retention of deciduous teeth as late as the 3rd
decade of
life.
5. Spacing between teeth and open bite.
6. Retardation of endochondral ossification results in disturbed cranial
base and arrested in growth.
Hypoparathyroidism is characterized by the following dental manifestations:-
1. Enamel hypoplasia in horizontal lines
2.Shortened roots
3. Hypodontia
4. Delay or cessation of dental development
5. Alteration in facial muscles
Hypopituitarism (Dwarfism)
1.Retarded growth, the patients looks younger than he or she is, with
no physical disproportion.
2.Delayed eruption of deciduous and permanent teeth, the pulpal walls
are wide and parallel and apical closure is delayed.
 Causes of DTE: retardation of endochondral ossification results in
disturbed cranial base and arrest in growth
• Oral clefts:
Definition: the word cleft is a defect which results from failure of fusion of any
of the facial processes. the most common clefts occur in the upper lip and palate
region and rarely occur in the lower jaw.
Incidence: varied in different parts of the world. It is generally about (1:800-
1000) live births.
Types: Pre alveolar (simple), alveolar and post alveolar according to their
occurance in the lip, alveolus or palate respectively.
1. Cleft lip: -unilateral or bilateral and rarely median
-Range from simple notch in the lower border of the lip to a broad
cleft extending to the floor of the nose
-an accompanying cleft of the alveolus and palate is often found in
the more severe cases.
2. Cleft palate: -clefts extend forwards from uvula and may involve the soft
palate only or the hard palate also may be involved to the
incisive foramen
- complete unilateral cleft: extending from the uvula to the
incisive foramen in the midline then deviating to one side and

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meeting the alveolar process in the area of lateal incisor and
then into the lip.
-complete bilateral cleft: extending forward bilaterally from
the incisive foramen to the alveolus and lip. If the alveolus
were bilaterally involved, the premaxilla remains suspended
from the primitive nasal septum.
Complication: infants born with hare lip and cleft palate are usually able to live
but present many problems in care and treatment:
1-feeding problems and tendency to aspirate food and are therefore susceptible to
respiratory diseases.
2-infection in the nasopharynx which tracks up the pharyngotympanic tubes,
leading to otitis media and deafness
3-problems in speech and esthetics as well asocial and psychological problems.
 Cause of DTE: surgical repair can be associated with scarring in the
maxillary region, which can produce growth deficiencies in all three
planes of space.
• Long term chemotherapy:
-Altered dental growth and development is a frequent complication in long-term
cancer survivors who received high-dose chemotherapy and/or head/neck radiation
for childhood malignancies.
-The extent and location of dental and craniofacial anomalies largely depend on
the age at which cancer therapy was initiated and the cancer regimen used.
- Children younger than 5 or 6 years at the time of treatment (particularly those
who undergo treatment that involves concomitant chemotherapy and head and
neck radiation) appear to have a higher incidence of dental and craniofacial
anomalies than do older patients or those who undergo only chemotherapy.
-Developmental disturbances in children treated before age 12 years generally
affect size, shape, and eruption of teeth as well as craniofacial development:
1-Abnormal tooth formation manifests as decreased crown size, shortened and
conical shaped roots, and microdontia; on occasion, complete agenesis may occur.
2-Eruption of teeth can be delayed, including increased frequency of impacted
maxillary canines.
3-Shortened root length is associated with diminished alveolar processes, leading
to decreased occlusal vertical dimension.

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4-Conditioning-induced injury to maxillary and mandibular growth centers can
compromise full maturation of the craniofacial complex.
• Drugs(phenytoin):
-The most common oral side effect of antiepileptic drugs(as phenytoin) seen in the
dental office is gingival hyperplasia.
-Gingival hyperplasia is characterized by unusual growth of the gingival sub
epithelial connective tissue and epithelium, for unknown reasons; it is reversed
once the drug is discontinued.
 Cause of DTE: Gingival enlargement may cause delays in permanent
teeth eruption and malocclusions in children with mixed dentition
• X radiation :
has also been shown to impair tooth eruption.
 Causes of DTE:
1- Ankylosis of bone to tooth
2- Root formation impairment
3- periodontal cell damage
3- insufficient mandibular growth
• Anemia:
Definition: it is a lowered ability of blood to carry oxygen due to decrease in
amount of RBCs or amount of hemoglobin in blood.
Symptoms: the most common symptoms are:
1-weakness, fatigue and general malaise.
2-dyspnea (shortness of breath)
3-pallor (pale skin, lining mucosa, conjunctiva and nail beds)
Anemia also have been correlated with DTE and other abnormalities in dentofacial
development.
 Also delayed eruption occurs in syndromes with:
1-General growth disturbances
2-Maxillary and mandibular hypoplasia
3-Disturbances of tooth formation
4-Gingival fibromatosis
5-Disturbances of bone metabolism

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• Down syndrome:
Defintion: It is the most common clinically recognizable syndrome with severe
learning difficulty. It is caused by triosomy of chromosome21 giving a total
complement of 47 chromosomes instead of 46.
Manifestations:
1-Eyes have an upward and outward slant
2-Skin fold on the inner side of the eye (epicanthal fold)
3-The eye slit is narrow and short
4-The face has a flat appearance
5-The head is smaller than average
6-Poor muscle tone and short stature.
7-Hypoplastic maxilla.
8-Protrusive enlarged tongue.
9-Hypoplasitic teeth and short roots.
10-Oligodontia.
11-Rapidly progressive periodontal disease.
12-Cardiac anomelies in 40%
13-Generalized susciptibility to infection
 Causes of DTE: hypoplastic dental defects and hypoplasia of maxilla.
• Cleidocranial dysplasia:
Defintion: It is an autosomal dominant inherited disorder of bony
development chiefly involves skull and clavicles.
Mamifestations:
1-Large head with prominent frontal bones
2-Wide sutures and fontanelles
3-Small face
4-Aplasia/hypoplasia of clavicles
5-Supernumerary teeth
 Causes of DTE: supernumerary teeth and
abnormal bone metabolism
• Gardner syndrome:
Definition: It is an autosomal dominant inherited disorder characterized by:
1-Multiple polyposis of large intestine (premalignant)
2-Multiple osteomas of skull/facial bones

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3-Multiple Epidermoid/sebaceous skin cysts
4-Multiple impactes supernumerary teeth
 Causes of DTE: osteomas in the jaws and supernumerary teeth.
• Ectodermal dysplasia:
Definition: it is an inherited disorder in which there are abnormalities of two or more
ectodermal structures such as the hair, teeth, nails, sweat glands.
Manifestations:
1-Sparse scalp hair, eyelashes, eyebrows
2-Inability to sweat
3-Defect in nails
4-High forhead, depressed nasal bridge
5-Decreased anterior face height
6-Dental abnormalities (oligodontia/anodontia)
7-Microdontia, tooth shape abnormalities
 Causes of DTE: abnormalities of tooth formation
• Cherubism:
Defintion:it is a familial multilocular cystic disease of jaws that is inherited as
an autosomal dominant trait.
Manifestations:
1-Cystic, fibrous jaw lesions
2-Bilateral symmetric jaw expansion
3-Moon face.
3-Slight upward look to heaven by the increased rim of
sclera exposed by retraction of the lower eye lid due to
stretching of facial skin over the expanded bone (cherubic
appearance)
4-Aplasia of teeth
 Causes of DTE: cystic jaw lesions (giant-cell
granulomas)
• Gorlin syndrome:
Definition: it is an autosomal dominant inherited disorder with numerous
manifestations but the main signs are:
1-Frontal and temporal bossing
2-Hypertelorism(increased distance between eyes)
3-Multiple odontogenic keratocysts

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4-Multiple nevoid basal cell carcinoma of skin
5-Bifid ribs and vertebral deformities
6-Abnormalities of calcium and phosphate metabolism
 Causes of DTE: multiple OKC that interfere with teeth eruption
• Osteogenesis imperfecta:
Definition: it is a rare genetic disease, transmitted as an autosomal dominant
trait resulting in mutating defect in osteoblasts and defect of biosynthesis of
bone matrix which isformed mainly of type I collagen, with subsequent
deficiency of ossification so that the cortical bone is thin and the cancellous
bone hasfine trabeculae which are widely separated with large medullary
spaces.
Manifestations:
1-Bone fragility and multiple fractures
2-Blue sclera caused by scleral thinness allowing
the pigmented coat of the choroid to become
visible.
3-Dentinogenesis imperfecta
4-Deafness in adults
 Causes of DTE: disturbance in bone metabolism and teeth formation.

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5-Diagnosis and clinical implications:
Accurate diagnosis of DTE is an important but complicated process.
Although many terms are used to characterize DTE, they all refer to 2
fundamental parameters that influence this phenomenon:
(1) expected tooth eruption time (chronologic age), as derived from
population studies.
(2) biologic eruption, as indicated by progression
of root development.
These parameters are currently used as clinical markers for orthodontic
treatment planning. Suri, Gagari, and Vastardis 2008 proposed a
classification scheme (Fig 1) that takes into account these parameters ,
allowing the clinician to follow a diagnostic algorithm for DTE and its
etiology.
In this scheme, they sequentially examine several aspects of tooth eruption.
First, they examine the patient’s age and clinically apparent dentition. A
second step includes determining the presence or absence of a factor that
adversely affects tooth development. This will prompt the clinician to consider
certain diseases that result in defects of tooth structure ,size, shape, and color.
If tooth development is unaffected by any such factor, the third step is to
consider the patient’s dental age as evidenced by root formation.
When teeth do not erupt at the expected age (mean _ 2 SD), a careful
evaluation should be performed to establish the etiology and the treatment
plan accordingly.
The importance of the patient’s medical history cannot be overstated. A wide
variety of disorders has been reported in the literature to be associated with
DTE. Family information and information from affected patients about
unusual variations in eruption patterns should be investigated.
Clinical examination should be done methodically and must begin with the
overall physical evaluation of the patient. Although the presence of
syndromes is usually obvious, in the mild forms, only a careful examination
will reveal the abnormalities. Right-left variations in eruption timings are
minimal in most patients, but significant deviations might be associated with

32. Safa Basiouny
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(for example) tumors or hemifacial microsomia or macrosomia and should
alert the clinician to perform further investigation.
Intraoral examination should include inspection, palpation, percussion.
❖ Inspection for gross soft tissue pathology, scars, swellings, and fibrous or
dense frenal attachments.
❖ Careful observation and palpation of the alveolar ridges buccally and
lingually usually shows the characteristic bulge of a tooth in the process of
eruption. Palpation producing pain, crackling, or other symptoms should be
further evaluated for pathology. In patients in whom a deciduous tooth is
overretained, with respect to either the contralateral side or the mean
exfoliation age for the patient’s sex and ethnicity, the deciduous tooth and the
supporting structures should be thoroughly examined. Ankylosed teeth also
interfere with the vertical development of the alveolus. Retention of the
deciduous tooth might lead to deflection of the succedaneous tooth and
resorptive damage of the adjacent teeth.
A panoramic radiograph is ideal for evaluating the position of teeth and the
extent of tooth development, estimating the time of emergence of the tooth into
the oral cavity, and screening for pathology.
The parallax method (image/tube shift method, Clark’s rule, buccal object
rule) and 2 radiographs taken at right angles to each other are suggested for
radiographic localization of tumors, supernumerary teeth, and displaced teeth,
which require surgical correction.
Computed tomography can be used as the most precise method of radiographic
localization, although its additional cost and relatively high radiation dose limit
its use.
Clinical implications:
1-DTE is often seen in the region of the maxillary canines. The maxillary
canine develops high in the maxilla and is the only tooth that must descend
more than its length to reach its position in the dental arch. When pathologic
conditions are ruled out, the etiology of DTE of the canines has been
suggested to be multifactorial. Specifically, 3 factors have been proposed for
consideration:

33. Safa Basiouny
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(1) DTE of the canine might simply reflect ectopic development of the
tooth germ that could be genetically determined.
(2) there might be a familial association to them.
(3) in a significant number of cases of delayed eruption of the canine, an
abnormality of the lateral incisor in the same quadrant is observed.
A developmental anomaly might exist in this part of the maxilla, which
contains one of the embryonic fusion lines, and DTE of the canines in many
cases could be part of a hereditary syndrome.
2-Permanent tooth agenesis (excluding the third molars) in the general
population has been noted to range from 1.6% to 9.6%. The incidence of tooth
agenesis in the deciduous dentition is in the range of 0.5% to 0.9%. After third
molars, the most commonly missing teeth are mandibular second premolars
and maxillary lateral incisors. Thus, congenital absence of a tooth should also
be suspected when considering DTE.

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fig 1. A diagnostic algorithm for DTE

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6-Therapeutic consideration for patient with DTE
(Management):
DTE presents a challenge for orthodontic treatment planning. A number of
techniques have been suggested for treating DTE. Once the clinical
determination of chronologic DTE (_2 SD) has been established, a panoramic
radiograph should be obtained. The screening radiograph can be used to
assess the developmental state of the tooth and rule out tooth agenesis.
The main considerations for teeth affected by DTE are
(1) the decision to remove or retain the tooth or teeth affected by DTE.
(2) the use of surgery to remove obstructions.
(3) surgical exposure of teeth affected by DTE.
(4) the application of orthodontic traction.
(5) the need for space creation and maintenance.
(6) diagnosis and treatment of systemic disease that causes DTE.
A- DTE with defective tooth development:
If there is defective tooth formation, the first step should be to assess whether
the defect is localized or generalized.
❖ In the deciduous dentition
-close observation of the defective deciduous tooth or teeth is the usual
course of treatment, and space should be maintained where indicated.
-Unerupted deciduous teeth with serious defects should be extracted, but the
time of extraction should be defined carefully by considering the
development of the succedaneous teeth and the space relationships in the
permanent dentition.
❖ In the permanent dentition
-Management has traditionally focused on the restorative challenges of
these patients once the teeth have erupted.

36. Safa Basiouny
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- No systematic approach to accelerate the eruption of malformed retained
teeth could be found in the literature. However, Andreasen1997 suggests
that in patients in whom the defect is not in the supporting apparatus of
the tooth, exposure of the affected teeth might bring about the eruption.
-Severely malformed teeth usually must be extracted. Often, defective
teeth can serve as abutments for restorative care once they have erupted.
B- DTE with no obvious developmental defect in the affected tooth or teeth
on the radiograph:
In this case, root development (biologic eruption status), tooth position, and
physical obstruction (radiographically evident or not) should be evaluated.
❖ In the absence of ectopic tooth position and physical obstruction
-if the biologic eruption status is within normal limits periodic observation
is the recommended course of action.
- For a succedaneous tooth if root formation is inadequate extraction of the
deciduous tooth or exposure to apply active orthodontic treatment is not
justified.
-If the tooth is lagging in its eruption status active treatment is
recommended when more than 2/3 of the root has developed.
❖ In the presence of ectopic tooth position on radiographic
examination
-Often, some deviations self-correct, but significant migration of
the tooth usually requires extraction.
- If self-correction is not observed over time active treatment should
begin. Exposure accompanied by orthodontic traction has been shown to be
successful.
-In patients in whom the ectopic teeth deviate more than 90° from the
normal eruptive path autotransplantation might be an effective
alternative
❖ In the presence of An obstruction
-obstruction might or might not be obvious on the radiographic survey.

37. Safa Basiouny
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- A soft tissue barrier to eruption is not discernible on the radiograph, but,
regardless of etiology, an obstruction should be treated with uncovering
procedure that includes enamel exposure.
- Supernumerary teeth,tumors, cysts, and bony sequestra are examples of
physical obstructions visible on the radiographic survey Their removal
usually will permit the affected
tooth to erupt.
▪ In the deciduous dentition
DTE due to obstruction is uncommon, but scar tissue (due to trauma) and
pericoronal odontogenic cysts or neoplasms are the usual causes in cases of
obstruction. Trauma is more common in the anterior region, but cysts or
neoplasms are more likely to result in DTE in the canine and molar regions.
Odontomas are reported to be the most common of the odontogenic lesions
associated with DTE.
Treatment options for deciduous DTE range from:
o Observation
o removal of physical obstruction with and without exposure of the
affected tooth
o orthodontic traction on rare occasions
o extraction of the involved tooth.
▪ In the permanent dentition
-Removal of the physical obstruction from the path of eruption is
recommended.
-When neoplasms (odontogenic or nonodontogenic) cause obstruction
the surgical approach is dictated by the biologic behavior of the lesion.
-If the affected tooth is deep in the bone the follicle around it should be
left intact.
-When the affected tooth is in a superficial position exposure of the
enamel is done at tumor removal.
- Occasionally, the affected tooth must be removed.
-Four surgical approaches have been recommended for uncovering impacted
teeth. These include:
o Gingivectomy
o apically positioned flap
o flap/closed eruption
o preorthodontic uncovering technique.
-When arch length deficiency creates a physical obstruction either
expansion of the dental arches or extraction might be necessary to obtain the

38. Safa Basiouny
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required space. Extraction of either the affected or adjacent teeth can be
performed.
-Occasionally, several teeth in a quadrant might be unerupted, and this can
present an orthodontic challenge because of the lack of adequate anchorage
elements Osseointegrated implants might offer viable alternatives for
anchorage in such cases.
Two opinions seems to exist regarding management of the tooth delayed in
eruption after removing the physical barrier:
1-Exposure of the tooth delayed in eruption at the surgical removal of the
barrier.
2-Removing the obstruction and providing sufficient space for the unerupted
tooth to erupt spontaneously. Most teeth (54%-75%) erupt spontaneously in
the latter situation; however, the eruption rate might be protracted.
-The decision to use orthodontic traction in most case reports seems to be a
judgment call for the clinician. No conclusive guidelines could be derived
from the literature regarding when active force should be used to aid
eruption of the exposed tooth. Occasionally, a deciduous tooth can be a
physical barrier to the eruption of the succedaneous tooth. In most cases,
removing the deciduous tooth will allow for spontaneous eruption of the
successor.
C- DTE associated with systemic disease:
-Whenever DTE is generalized the patient should be examined for
systemic diseases affecting eruption, such as endocrine disorders, organ
failures, metabolic disorders, drugs, and inherited and genetic disorders.
-Various methods have been suggested for treating eruption disorders in
these conditions. These include:
o no treatment (observation).
o elimination of obstacles to eruption (eg, cysts, soft tissue
overgrowths).
o exposure of affected teeth with and without orthodontic traction.
o autotransplantation, and control of the systemic disease.

39. Safa Basiouny
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Fig 2. Flow chart of treatment options for DTE affecting permanent dentition

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1. Suri L, Gagari E, Vastardis H. Delayed tooth eruption: Pathogenesis,
diagnosis, and treatment. A literature review. Am J Orthod Dentofacial
Orthop. 2004;126:432-45.
Louis: Elsevier
St.
edition.
th
Ten Cate's oral histology.8
2.Nanci A et al.
Mosby.2008
3.Almonaitiene R, Balciuniene I, Tutkuviene J. Factors influencing
permanent teeth eruption. Part one-general factors. Stomatologija, Baltic
Den and Maxillofacial J.2010; 12: 67-72.
4.Salzman J A. Orthodontics in daily practice.
5.Cobourne T M, BiBiase T A. Handbook of orthodontics . St. Louis:
Elsevier Mosby.2010