Dental Anomalies
Dental Anomalies
Introduction
Anomaly (irregular) is opposite
from what is known as normal. Disturbance of the epithelium and mesenchyme can
markedly alter the normal odontogenesis leading to the developmental anomaly of
teeth.
Depending on the developmental stage in which the difference has taken place, various anomalies could take place, for example, anomalies of number, structure, size and/or shape. A majority of uncommon dental anomalies occur during childhood years. Developmental dental anomalies are classified according to their abnormalities in number, shape, colour, structure, texture, eruption, exfoliation and position. Local as well as systemic factors may be responsible for these developmental anomalies. Such effects may begin before or after birth, therefore both the dentition might be affected.
Depending on the developmental stage in which the difference has taken place, various anomalies could take place, for example, anomalies of number, structure, size and/or shape. A majority of uncommon dental anomalies occur during childhood years. Developmental dental anomalies are classified according to their abnormalities in number, shape, colour, structure, texture, eruption, exfoliation and position. Local as well as systemic factors may be responsible for these developmental anomalies. Such effects may begin before or after birth, therefore both the dentition might be affected.
More than 300 genes have been
identified to be expressed in teeth that are responsible for odontogenesis.
Defects in these genes have been found to be one of the reasons for variation
of the morphology of tooth. Diagnosing dental abnormality needs a thorough
evaluation of the patient, involving a medical, dental, familial and clinical
history. Clinical examination and radiographic evaluation and in some of the
cases, specific laboratory tests are also needed. Dental anomalies
including the number of teeth involve hypodontia (one or more missing teeth),
oligodontia (six or more missing teeth), anodontia (complete absent of teeth)
and hyperdontia (one or more extra teeth, also identify as supernumeraries).
Variations in the size of teeth include microdontia (teeth smaller than normal)
and macrodontia (enlargement of the teeth compare to normal). Both these
situations may be either generalised to all the teeth or isolated to one or
several teeth. Alterations in the morphology of teeth include double teeth (fusion
and gemination), talon cusp, dens evaginatus (DE) and dens invaginatus (DI)
(dens in dente).Early diagnosis of dental anomalies should allow for more
comprehensive prolonged treatment planning, more proper prognosis and in
certain instances, less extensive interception.
Description of the anomalies
Gemination
Tannenbaum and Alling in 1963
determined gemination as the formation of equivalent of two teeth from the same
follicle, with evidence of an endeavour for the teeth to be completely
separate.
Gemination also determined as
twin teeth, twin formations, joined teeth, fused teeth or dental twinning is
commonly seen in the maxillary anterior area.
Geminated teeth arise from an
endeavour at the division of a single tooth germ by invagination, results a
single tooth with two completely separated crowns; or a large, incompletely
separated crown having a single root and root canal. This condition can be
confirmed radiographically. The anomalous tooth has an enlargement in
mesial-distal diameter than normal and is counted as one.However, the total
number of teeth in dental arch is also normal
The aetiology of geminated
teeth stays unknown but nutritional deficiency, endocrine influences,
infectious/inflammatory progress, excessive ingestion of medicines, congenital
diseases; local trauma and ionising radiation are included as causative
factors.
Clinically, gemination
happening in the anterior tooth side causes aesthetic disorders related to
tooth alignment, spacing and arch asymmetry. The presence of deep grooves on
the surface forms it susceptible to caries and periodontal problems by
facilitating bacterial plaque accumulation. The eruption of adjacent tooth may
also be obstacle.
Fusion
Pindborg defined fusion as the
combination between dentin and enamel of two or more separate developing
teeth. Fusion is developmental anomaly of dental hard tissue and defined
as the joining of two developing tooth germs resulting in a single large tooth structure
different treatment methods can be used according to the requirements of
situation. This anatomic abnormality happens more often in deciduous
dentition with a predilection for the anterior region.
Fusion can be complete
(total/true fusion) or incomplete (partial/late fusion), it depends on level of
development. If fusion starts before calcification stage, the teeth unite
completely and the crown incorporates enamel, dentin, cementum and pulp of both
the teeth. Incomplete fusion happens at a later level and resultant tooth may
exhibitive separate crowns and limited to root alone with combined or separate
pulp canals.
Different theories have been
put forward to describe the aetiology of fusion. It has been suggested that
when the tooth germs are too close together they come in contact and fuse as
they develop because of the physical pressure or force generated during growth.
The other theories suggested the use of thalidomide or occurrence of viral
infection while pregnancy A genetic aetiology has also been
included. Fusion has been noted with congenital anomalies like cleft lip
and also in X-linked congenital conditions. Some dental and non-dental
abnormalities such as supernumerary teeth, hypodontia, peg-shaped incisors,
dens in dente, nail disorders, syndactyly, successional conical teeth,
macrodontia and double permanent teeth have been attendant with fusion.
On some occasions, two
independent pulp chambers and root canals can be seen. However, fusion can also
be the union of a normal tooth bud to a supernumerary tooth germ. Fusion
may cause aesthetic disorders and occlusal disturbances due to crowding and
irregular morphology and shape, respectively. The presence of deep grooves may
prepare for caries or periodontal diseases and cause early pulp exposure. The
larger root mass and increased surface region would result in late resorption
and subsequently bring late or ectopic eruption of the permanent successors.
Concrescence
Concrescence is determined as
the cemented combination of two adjacent teeth without confluence of the
underlying dentin showing independent pulp chambers and root canals. It
may happen before or after the teeth have erupted. This condition can frequently
be attributed to trauma or crowding of teeth. If the condition
happens while developmental stage, it is called true/developmental concrescence
and achieved/post-inflammatory concrescence if after root formation.
Concrescence is seen often in
the posterior maxillary region. The developmental pattern frequently involves a
second molar tooth in which its roots closely approximate to the adjacent
impacted third molar. Few cases have shown the concrescence of a
third molars and a supernumerary tooth
It is suspected that space
restriction while developmental stage, local trauma, too much occlusal force,
or local infection after development play an important role in the happening of
concrescence. True concrescence is attributed to the close proximity
of developing roots of the adjacent teeth whereas achieved concrescence may
result from a chronic inflammatory response to a non-vital tooth. The
combination may vary from one small site to a solid cemented mass along the
whole extent of approximating root surfaces.
Radiographic examination is
necessary when concrescence is suspected clinically. Although in cases of
superimposition of two closely approximated teeth, additional radiographic
projections at different angulations may be required.
Concrescence should be identified
to reduce the risk of complications associated with surgical
procedures. It may also affect the extraction of an adjacent tooth and may
cause fracture the tuberosity or floor of the maxillary sinus. In such cases,
sectioning of tooth should be considered to reduce adverse and unexpected
outcomes.
Dilaceration
The term dilacerations was
first used by Tomes in 1848, and it is defined as a deviation or bend in the
linear relationship of a crown of a tooth to its root. Based on this
definition, dilacerations is distinguished from the rarely used term flexion,
which is defined as a tooth with a hooked or a bent root. It is an
abnormal angulation or bend in the root and less frequently, the crown of a
tooth. Most cases are idiopathic and have no clinical
feature. Dilaceration can occur in both permanent and primary dentitions,
however in the latter is very low. The prevalence rate is greater in
posterior teeth and in the maxilla. Mentioned by some authors, a
tooth is considered to have a dilaceration towards mesial or distal direction
if there is a 90° angle or more along the axis of the tooth or root, whereas
others determined dilaceration as a deflection from the normal axis of the
tooth of 20°. The most accepted reason of dilaceration is acute mechanical
injury to the primary predecessor tooth that head to the dilaceration of the
underlying developing succedaneous permanent tooth. Crown
dilaceration is rarer than root dilacerations. Crown dilacerations are usually
observed in the permanent maxillary incisors followed by mandibular incisors.
Clinically, the maxillary incisors show a lingual deviation during the
mandibular incisors incline labially. Crown dilaceration is the
reason of a developmental anomaly in which there has been an abrupt change in
the axial inclination between the crown and the root of a tooth. Two possible
reason of dilacerations are trauma and developmental disturbances, and it has
also been suggested that it might be associated with some developmental
syndromes. The other possible contributing factors that have been noted
such as scar formation, developmental anomaly of the tooth germ, facial
clefting, advanced root canal infections, ectopic development of the tooth germ
and lack of space and area, effect of anatomic formations (e.g., cortical bone
of the maxillary sinus, mandibular canal, or nasal fossa, which might perverse
the epithelial diaphragm), presence of an adjacent cyst, tumour, or odontogenic
hamartoma, mechanical interposition with eruption (e.g., from an ankylosed
primary tooth that does not resorb), tooth transplantation, extraction of
primary teeth and hereditary and genes factors.
Identification and diagnosis of
dilaceration often needs radiographs taken at different
angulations. Mesial or distal root curvatures of dilacerated roots
are perspicuity discernible on periapical radiographs. However, if the
curvature lies in a labial-buccal direction, the central X-ray beam crosses
almost parallel to the deviating area of the root giving a 'bulls eye' like
appearance, but still periapical radiographs are the most appropriate way
to diagnose the presence of root dilacerations. Clinical identification of
dilaceration is necessary because it can lead to non-eruption, longer retention
of predecessor tooth or conceivable apical fenestration of the buccal or labial
cortical plate.Dilaceration makes a challenge for endodontic or orthodontic
treatment as well as discomfort in extraction.
DI also determines as the
pregnant woman anomaly, wide compound odontoma, and dens in dente, happens as a
consequence of an invagination on the external surface area of the tooth crown
before calcification. The endodontic treatment of invaginated teeth may be
challenging cause of difficulties in accessing the root canals and also reason
of complex variations of internal morphology. The invagination ranges from
a short pit limited to the crown to a deep invagination into the root, at times
widening to or beyond the root apex. The most severe forms are odontome-like
and are mostly termed invaginated odontomes. Most of the cases are
encountered in maxilla with the maxillary lateral incisors being mostly
affected, followed by central incisors, premolars, canines and molars.The
classical radiographic appearance of coronal DI is a pear-shaped invagination
of enamel and dentin with a narrow structure at the opening on the surface area
of the tooth. The in folding of the enamel lining is more radio-opaque than the
surrounding tooth construction aiding easy recognition.
Oehlers et al.
grouped coronal DI into three types according to the radiographic appearance
such as:
- Type
I: An enamel-lined minor form happening within the confines of the crown
not extending beyond the cementoenamel junction (CEJ)
- Type
II: An enamel-lined form which invades the root but remains limited as a
blind sac. It may or may not connect with the dental pulp
- Type
IIIA: A form which crosses through the root and connected laterally with
the periodontal ligament space through a pseudo-foramen. There is usually
no communication with the pulp, which lies also compressed within the root
- Type
IIIB: A form which crosses through the root and perforating at the apical
region through a pseudo-foramen. The invagination may be completely lined
by enamel, but mostly cementum will be found lining the invagination.
A radicular form of DI has also
been defined by Oehlers et al. which is thought to arise because of
the proliferation of Hertwig's root sheath. The root of this kind of tooth is
enlarged which can be demonstrated radiographically.
Infection, trauma, pressure or
difficulty from the growing dental arch is thought to be responsible for
DI. A focal failure of growth or a proliferation of a part of the inner
enamel epithelium may be included in the invagination. Ohlers
suggested a distortion of the enamel organ and further protrusion of a part of
the enamel organ resulting in the formation and shaping of enamel-lined
channel.
The invagination acts as a
channel for entrance of irritants and microorganisms; and prepare for the
development of dental caries. Since the thickness of enamel is less, pulp
necrosis happens at an earlier age. Coronal DI can also go ahead to abscess
formation, retention of neighbouring teeth, cysts, internal resorption,
cellulitis, etc.
Dens Evaginatus
DE is a developmental
aberration of a tooth resulting in formation of one accessory cusp whose
morphology of shapes has been determined as abnormal tubercle, elevation,
protuberance, excrescence, extrusion or a bulge. It is also mentioned to as
tuberculated cusp, accessory tubercle, occlusal tuberculated premolar, Leong's
premolar, evaginatus odontoma and occlusal pearl. Currently, DE is
the preferable terminology and was first recommended by Oehlers et al.
in 1967. This unusual anomaly projects above the adjacent tooth surface
area, exhibitive enamel covering a dentinal core that commonly contains pulp
tissue; occasionally having slender pulp horn which extends to different
distances within the dentinal core. The tubercles of DE have been
differentiated from the cusp of carabelli which is a normal anatomical
formation and is differentiated from DE by the absent of a pulp core.
The happening of DE shows too
much racial differences with a higher spreading among people of mongoloid
origin. It is commonly associated with the occlusal surface area of
premolars. Schulze (1987) distinguished the following five types of DE for
posterior teeth by the location and area of the tubercle.
1.
A cone-like enlargement of the lingual cusp
2.
A tubercle on the disposed plane of the lingual cusp
3.
A cone-like enlargement of the buccal cusp
4.
A tubercle on the disposed plane of the buccal cusp
5.
A tubercle arising from the occlusal surface area obliterating the
central groove.
When DE appears in the anterior
region area, it is commonly observed on the lingual surface and is known as a
talon's cusp. Early diagnosis and management of DE are necessary to
prevent occlusal interference, compromised aesthetics, carious developmental grooves,
periodontal problems because of excessive occlusal forces, or irritation of the
tongue while speech and mastication. Mitchell was the first to
identify this anomaly in 1892, which was later named talon by Mellor and Ripa
because of its resemblance to an eagle's talon. It is usually seen in the
maxillary lateral incisors region and has been associated with syndromes such
as Rubinstein and Taybi, Berardinelli-Seip, Mohr, Ellis-van Creveld,
Sturge-Weber and incontinentia pigmenti achromians. It differentiated
in size, shape, length and mode of attachment to the crown and ranges from an
enlarged cingulum to a large, well-delineated cusp extending beyond the incisal
region of the tooth. The cusp is composed of normal enamel and dentin
including varying extensions of pulp tissue. It may also communicate with the
incisal edge to produce a T-form or, if more cervical, a Y-shaped crown
contour.
Talon cusp is an unusual anomaly, whose etiology may be disturbances in the morph differentiation stage. Talon cusp is a rare entity in which a prominent wisplike structure originates from the cervical area of lingual or labial surfaces of the anterior teeth, happening lingually with the most frequency.
Talon cusp
Talon cusp is an unusual anomaly, whose etiology may be disturbances in the morph differentiation stage. Talon cusp is a rare entity in which a prominent wisplike structure originates from the cervical area of lingual or labial surfaces of the anterior teeth, happening lingually with the most frequency.
Hattab et al.
classified talons' cusps into three types based on the degree of cusp shapes
formation and extension:
- Type
1: Talon - refers to a morphologically well-delineated accessories cusp
that prominently projects from the palatal (or facial) surface area of a
primary or permanent anterior tooth and extends at least half the distance
from CEJ to the incisal edge
- Type
2: Semi talon - refers to an additional cusp of a millimeter or more
extending less than half the distance from CEJ to the incisal edge region.
It may blend with the palatal surface area or stand away from the rest of
the crown
- Type
3: Trace talon - an enlarged or eminent cingula and their variations,
i.e., conical, bifid or tubercle-like.
The DE or talons cusp may have
fracture or be abraded as soon as the tooth comes into occlusion, exposing the
pulp. Hence, early identification of this anomaly and prompt treatment
should be instituted to avoid endodontic complications.
Enamel pearls
Enamel which is normally
confined to the anatomic crowns of human teeth may be found ectopically on the
root, either as cervical enamel projections or enamel pearls.Enamel pearl is
determined as an ectopic globule of enamel that is firmly attached to the tooth
root. Enamel pearls may include completely of enamel connected to cementum
or root dentin or may indicate incorporation of a cone of dentin with or
without pulpal extension, the last two are referred to as composite enamel
pearls and the composite type without pulpal extension is the most usual type
of macroscopically detected enamel pearls. It has been mentioned to as an
enameloma, enamel droplet, enamel nodule, enamel exostoses and enamel globule.
It is found usually on the roots of maxillary molars, particularly the third
molars adjacent to the furcation or furrow of the root.
Enamel which is usually
restricted to the anatomic crowns of human teeth may be found ectopically on
the root, either as cervical enamel projections or enamel pearls. These
developmental aberrations in tooth morphology may prepare the affected area to
plaque accumulation and consequently brings periodontal breakdown. Early
diagnosis of these anomalies may meliorate the prognosis of the involved teeth.
Enamel pearl is determined as an ectopic globule of enamel that is firmly
connected to the tooth root. The size of clinically recognizable enamel pearls
may vary from 0.3-4 mm. Risnes (1974) observed enamel pearls on 2.28% molars of
8854 teeth examined grossly. The enamel pearls happened more usually on the
roots of maxillary molars, especially third molars. The usual site of area of
the enamel pearl is adjacent to the furcation or furrow of the root, especially
the bifurcation or trifurcation locations of maxillary and mandibular molars.
Maxillary 2 nd and 3 rd molars are
more usually included than the first molars.
Advanced localised periodontal
destruction has been attendant with cervical enamel projections and enamel
pearl, preparing for attachment loss
Taurodontism
Witkop determined taurodontism
as teeth with large pulp chambers in which the bifurcation or trifurcation has
displacement apically, so that the chamber has bigger apical-occlusal height
than in normal teeth and lacks the constriction at the level of CEJ. The
distance from the trifurcation or bifurcation of the root to the CEJ is bigger
than the occlusal-cervical distance.
This anomaly was first
mentioned in the remnants of prehistoric hominids by de Terra in 1903 and by
Gorjanovic-Kramberger and Aldoff in 1907. Pickerill in 1909 noted
this in modern man. Although the term 'taurodontism' was first used by Sir
Arthur Keith in 1913 to defined the teeth of prehistoric people, the
Neanderthals and Heidelberg. He coined this term from the Latin word tauro (for
bull) and Greek term dont (for tooth) due to the morphological
resemblance of affected tooth to the tooth of ungulates or cud chewing animals.
Shaw has classified taurodontism arbitrarily based on comparative degree of
apical displacement of floor of pulp chamber into hypo, meso and
hyper-taurodontism.
Peg-shaped laterals
A peg lateral is an undersized,
tapered, maxillary, small, lateral incisor.The tooth is conical in shape;
broadest cervically and tapers incisally to a blunt point. An uncommon
happening is that of a peg-shaped maxillary central incisor. Peg-shaped teeth grow
from a single lobe instead of four. The peg-shaped laterals are predominantly
genetically defined and can also be caused because of endocrinal
disturbances. Peg-shaped laterals may be attendant with other dental
anomalies such as tooth agenesis, canine transposition and over-retained
primary teeth. Studies of identical twins have showed that missing teeth and
peg-shaped lateral incisor might be a varied expression of the same genetic
trait. Early management of the peg-shaped laterals is important because of
psychological problems in children as well as for the correct development of
the stomatognathic system.
Fluorosis
Fluorosis is a cosmetic
situation that affects the teeth. It is happened due to overexposure to
fluoride during the first 8 years of life. This is the time when most permanent
teeth are being formed completely
Reason of the dental fluorosis
is the increasing in concentration within the fluoride microenvironment of the
ameloblasts while enamel formation. Fluorosis is increasing in mostly the
enamel proteins amelogenin and enamelin. In such an anomaly, both primary and
permanent dentition are effected. Symptoms of fluorosis range from tiny white
specks or streaks that may be unnoticeable to dark brown stains and rough,
pitted enamel that is difficult to clean. Teeth that are unaffected by
fluorosis are smooth and glossy. They should also be a pale creamy white. There
are ways of management of these anomaly such as, genetic counselling,
preservation of molar teeth with stainless steel crowns or nickel chrome or
gold onlays, composite resin veneers over anterior teeth, certain treatment
with porcelain and precious metal must be delayed until late adolescence.
Dentinal dysplasia (DD) is
frequent determined as rootless teeth. Clinical specification includes very
short or absent roots but the crowns are normal clinically, pulpal obliteration
similar to dentinogenesis imperfecta and often periapical radiolucencies surrounding
the defective roots. In such an anomaly all teeth and both dentitions are
affected. Management of this anomaly using prosthetic rehabilitation is an
effective treatment.
In general, two main classes of
DD are identified based on clinical and radiographic appearance. Witkop
proposed the classifications - Type I, or 'dentin dysplasia', and Type II or
'anomalous dysplasia of dentin'. Witkop later determined Type I as 'radicular
dentin dysplasia' and Type II as 'coronal dentin dysplasia' to show the parts
of the teeth that are primarily involved. It is a rare anomaly of unknown
aetiology that affects approximately one patient in every 100,000.
Histologically, in DD1, most of the coronal and mantle dentin of the root is
frequently reported to be normal, and the dentin defect is limited mainly to
the root.The third type of dentin dysplasia, DD3or 'focal odontoblastic
dysplasia', also has been proposed.
Regional odontodysplasia
Regional odontodysplasia (RO)
is a rare developmental anomaly that affects the primary and permanent
dentitions. This disturbance is generally localised in only one arch and its
aetiology is unknown yet. Clinically, the affected teeth have an abnormal shape
and are typically discoloured. Radiographically, these teeth show a ghost-like
aspect. This anomaly tends to effect several adjacent teeth within a particular
segment of the jaw, and usually does not cross the midline. RO
mostly involves one quadrant and affects the maxilla twice as frequently as the
mandible, with the left maxillary quadrant being the most frequently
affected quadrant. It has a predilection for the central and lateral
incisors, with higher prevalence in females. Treatment planning must be
designed separately for each individual case. It depends on many factors such
as the patient's age, medical history, involvement extension, teeth eruption,
aesthetics and the development stage of this anomaly
Hypodontia
Congenitally missing teeth
(CMT), or as usually named hypodontia, is a highly prevalent feature. Besides
an unfavourable appearance, patients with missing teeth mostly suffer from
malocclusion, periodontal damage, insufficient alveolar bone growth, less
chewing ability, inarticulate pronunciation and other
problems. Hypodontia is more prevalent in women so it is necessary
to manage these teeth aesthetically. The frequency rate of hypodontia is
variable in different sexes and races. Physical disruption of dental lamina may
cause obliteration of tooth buds and agenesis of tooth. This condition is seen
in orofaciodigital syndrome, Ellisvan syndrome and cleft lip and palate. It can
also be the result of metabolic misbalance that causes dental agenesis.
Finally, hereditary defect of the underlying mesenchyme may lead to
hypodontia.The treatment plan for CMT is challenging and requiring
multidisciplinary approach to achieve a successful outcome. A paediatric
dentist often initiates interdisciplinary treatment by the diagnosis of
hypodontia and maintenance of the primary teeth. Definitive treatment plan is
usually determined after the eruption of all permanent teeth.
Developmental anomalies of the
teeth require careful examination and treatment planning. Where one anomaly is
present, clinicians should suspect that other anomalies may also be present.
Developmental dental anomalies show variations and no two anomalies of the same
types are alike. Hence, knowledge of various criteria which have been put
forward for the identification and classification of the different anomalies is
essential to diagnose the condition and perform appropriate treatment.
Related topics
pericoronitis👆
Comments