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Abnormalities of the Teeth
Environmental Effects on Tooth
Structure Development
Environmental Effects on
Tooth Structure Development
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Visible environmental enamel defects can be classified into one
of three patterns:
Enamel hypoplasia – pits, grooves, or larger areas of missing
enamel
Diffuse opacities of enamel – variations in translucency or
normal thickness; increased white opacity with no clear
boundary with adjacent normal enamel
Demarcated opacities of enamel show areas of decreased
translucence, increased opacity, and a sharp boundary with
adjacent enamel; normal thickness
Environmental Effects on
Tooth Structure Development
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Common pattern occurs as result of systemic
influences (such as exanthematous fevers) which
occur during the first two years of life; horizontal
rows of pits or diminished enamel on anterior teeth
and first molars; enamel loss is bilateral
Similar pattern in cuspids, bicuspids, and second
molars when the inciting event occurs at age 4-5
Enamel Hypoplasia associated
with exanthematous fevers
Turner’s Hypoplasia
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(1)
Secondary to periapical inflammatory disease of
the overlying deciduous tooth
Enamel defects vary from focal areas of white,
yellow or brown to extensive hypoplasia
involving the entire crown.
Most frequently affects permanent bicuspids
Traumatic injury to deciduous teeth also causes
Turner’s teeth (45% of children sustain injuries
to primary teeth)
Turner’s Hypoplasia
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(2)
Trauma can displace the already formed hard
tooth substance in relationship to the
remaining soft tissue for root formation
causing dilaceration (a bend in the tooth root)
Severe trauma early in tooth development can
cause disorganization of the bud resembling a
complex odontoma. Severe trauma later on
can lead to partial or total arrest of root
formation.
Turner’s Hypoplasia
Turner’s Hypoplasia
Hypoplasia Caused by
Antineoplastic Therapy
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Degree and severity related to age, form of therapy
(chemotherapy/radiotherapy) and dose
Defects include hypodontia, microdontia, radicular
hypoplasia, enamel hypoplasia and discolorations
Radiotherapy effects more severe than chemotherapy
alone but sometimes used together
Dose of radiation as low as 0.72 Gy can cause mild
defects in enamel/dentin
Mandibular hypoplasia due to direct radiation, alveolar
deficiency or pituitary effects.
Hypoplasia Caused by
Antineoplastic Therapy
Dental Fluorosis
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Critical period is age 2-3, if fluoride levels
greater than 1 part per million are ingested
Fluoride comes from several sources besides
water: adult-strength fluoride toothpastes,
fluoride supplements, infant foods, soft drinks,
and fruit juices
Severity is dose dependent (higher intakes
during critical periods associated with more
severe fluorosis)
Dental Fluorosis
Dental fluorosis
Syphilitic Hypoplasia
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Mulberry molars – constricted occlusal tables with
disorganized surface anatomy resembling surface of a
mulberry
Anterior teeth called Hutchinson’s incisors, have
crowns shaped like straight-edge screwdrivers; incisal
taper & notch
Treatment - Most are cosmetic problems; treatment
includes acid-etched composite resin restorations,
labial veneers, and full crowns
Hutchinson’s triad
Syphilitic Hypoplasia
Moon’s (mulberry) molars
Hutchinson’s incisors
Postdevelopmental Loss
of Tooth Structure: Attrition
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Loss of tooth structure caused by tooth-to-tooth
contact during occlusion and mastication.
Pathologic when it affects appearance and
function.
Process can be accelerated by poor quality or
absent enamel, premature edge-to-edge
occlusion, intraoral abrasives, erosion, and
grinding habits.
Attrition
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Can occur in deciduous and permanent
dentitions
Most frequently, incisal and occlusal surfaces
involved
Large flat wear facets found in relationship
corresponding to pattern of occlusion
Interproximal contact points also affected
Over time, interproximal loss can result in
shortening of arch length
Postdevelopmental Loss
of Tooth Structure: Attrition
Postdevelopmental Loss
of Tooth Structure: Abrasion
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Pathologic loss of tooth structure secondary to
the action of external agent
Most common source is tooth brushing with
abrasive toothpaste and horizontal strokes.
Also pencils, toothpicks, pipe stems, bobby pins,
chewing tobacco, biting thread, inappropriate
use of dental floss
Abrasion
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Variety of patterns, depending on the cause
Toothbrush abrasion presents as horizontal
cervical notches on buccal surface of exposed
radicular cementum and dentin; degree of loss
greatest on prominent teeth
Thread-biting, pipe stem, bobby pins etc.,
produce rounded or V-shaped notches in incisal
edges of anterior teeth
Dental floss, toothpicks result in loss of
interproximal radicular cementum and dentin
Abrasion
Abrasion
Abrasion from partial clasp
Abrasion from improper flossing
Postdevelopmental Loss
of Tooth Structure: Erosion
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Loss of tooth structure by chemical reaction, not
that associated with bacteria (caries)
Secondary to presence of acid or chelating agent
Source can be dietary (e.g., vinegar, lemons),
internal (gastric secretions – perimolysis), or
external (e.g., acids, industrial, atmosphere)
“If it is not abrasion or attrition, it must be
erosion”
Erosion
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Commonly affects facial surface of maxillary
anteriors and appears as shallow spoon-shaped
depressions in cervical portion of the crown
Posterior teeth exhibit loss of occlusal surface,
where dentin is destroyed more rapidly than
enamel, resulting in concave depression of dentin
surrounded by elevated rim of enamel
Erosion limited to facial surfaces of maxillary
anterior dentition is usually associated with dietary
acid.
Erosion
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Tooth loss confined to incisal portions of anterior
dentition of both arches indicates environmental
source.
Erosion on palatal surfaces of maxillary anterior
teeth and occlusal surfaces of posterior teeth of
both dentitions probably caused by regurgitation
of gastric secretions.
Erosion
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Fizzy Drinks Are Major Cause of Teen Tooth Erosion Thu Mar 11, 7:06 PM ET LONDON
(Reuters) - Fizzy drinks are the major cause of tooth erosion in British teenagers but many
parents are not aware of the problem, researchers said on Friday.
The sodas and pop drunk by up to 92 percent of UK 14-year-olds wear away the enamel
protective coating on teeth. Dental erosion weakens teeth and can cause thinning or chipping of
the tooth edges.
"This research identifies fizzy drink as by far the biggest factor in causing dental erosion among
teenagers," said Dr Peter Rock, of Birmingham University.
"Drinking fizzy drinks only once a day was found to significantly increase a child's chances of
suffering dental erosion," he added.
Drinking four or more glasses of fizzy drinks a day raises a 12-year-old's chances of suffering from
tooth erosion by 252 percent. Heavy consumption in 14-year-olds increased the risk to 513
percent, according to research published in The British Dental Journal.
Unlike tooth decay, which results from high levels of sugar, erosion is caused by acidic substances
in the drinks. Even diet versions are harmful.
Drinking milk and water, instead, reduces the risk.
"Erosion is a growing problem among British teenagers, yet many parents don't understand the
difference between decay and erosion," said Professor Liz Kay of the British Dental Association.
"Parents need to understand...it is the acidity of certain products that cause erosion," she added
in a statement.
Erosion
Postdevelopmental Loss
of Tooth Structure: Abfraction
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Loss of tooth structure resulting from repeated
tooth (enamel & dentin) flexure produced by
occlusal stresses
Disruption of chemical bonds at cervical
fulcrum leads to cracked enamel that can be
vulnerable to abrasion and erosion
Abfraction
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Wedge-shaped defects limited to cervical area
Deep, narrow, V-shaped
Sometimes single tooth or subgingival
More common in mandibular dentition and
among those with bruxism
Abfraction
Treatment of Postdevelopmental
Loss of Tooth Structure
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Early diagnosis and intervention to restrict
severity of tooth loss
Patient education
Mouth guards
Limit (redirect) tooth brushing & flossing
Replacement of lost posterior teeth and
avoidance of edge-to-edge occlusion
Composite resins, veneers, onlays, full crowns
Internal & External Resorption
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Internal resorption is caused by cells located in
dental pulp. Rare, usually follows injury to
pulpal tissues.
External resorption is caused by cells in the
periodontal ligament. Most patients are likely
to have root resorption on one or more teeth.
Internal Resorption
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Internal resorption presents as a uniform, well-circumscribed
symmetrical radiolucent enlargement of pulp chamber. When it
affects the coronal pulp, crown can display pink discoloration (pink
tooth of Mummery)
External resorption
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External resorption presents with a “moth-eaten” loss of root
structure in which radiolucency is less well-defined and
demonstrates variations in density. Most cases of external
resorption involve apical or mid-portions of root
Internal & External Resorption
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Cervical pattern of external resorption is often
rapid (invasive resorption)
Multiple idiopathic root resorption – involves
several teeth, underlying cause not obvious
Treatment involves the removal of all soft tissue
from sites of dental destruction. For external
resorption, determine if an accelerating factor is
present, and eliminate it.
Internal & External Resorption
External Resorption
Internal resorption
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→
Internal resorption
External resorption-embedded tooth
Environmental
Discoloration of Teeth
Environmental
Discoloration of Teeth: Extrinsic
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Arise from surface accumulation of exogenous pigment
Bacterial stains – occur most frequently in children
Excessive use of tobacco, tea, coffee
Foods that contain abundant chlorophyll
Restorative materials, especially amalgam
Medications
Stannous fluoride and chlorhexidine
Extrinsic stains can be removed by polishing with fine
pumice, (sometimes with added 3% hydrogen peroxide);
recurrence is likely unless the associated cause is altered
Environmental Discoloration of Teeth: Extrinsic
Amalgam stain
Tobacco stain
Environmental Discoloration of
Teeth: Intrinsic
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Secondary to endogenous factors that discolor
underlying dentin
Congenital erythropoietic porphyria (Günther’s
disease) is an AR disorder of metabolism that
results in increased synthesis and excretion of
porphyrins
Hyperbilirubinemia due to jaundice,
erythroblastosis fetalis (hemolytic anemia of
newborns secondary to blood incompatibility,
usually Rh factor), biliary atresia (sclerosing
process of the biliary tree), and chlorodontia
(green discoloration).
Environmental
Discoloration of Teeth: Intrinsic
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Localized red blood cell destruction (pink discoloration
arising from hemoglobin breakdown within necrotic pulp
tissue when blood has accumulated in the head)
Lepromatous leprosy (pink discoloration secondary to
infection-related necrosis and the rupture of numerous
small blood vessels within the pulp
Medications (tetracycline)
Intrinsic stains are difficult to treat. Possible treatments
include full crowns, external bleaching of vital teeth,
internal bleaching of nonvital teeth, bonded restorations,
composite build-ups, and laminate veneer crowns.
Intrinsic Coloration of Teeth
Porphyria
Hyperbilirubinemia
Tetracycline Stain
Localized Disturbances in
Eruption
Localized Disturbances in
Eruption
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Eruption – the continuous process of movement
of a tooth from developmental location to
functional location
Impacted – teeth that cease to erupt due to
physical obstruction
Embedded – teeth that cease to erupt due to
lack of eruptive force
Ankylosis – teeth that cease to erupt due to
anatomic fusion of tooth with alveolar bone
Localized Disturbances in
Eruption
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Primary impaction of deciduous teeth is
extremely rare. Most commonly involves
second molars often due to ankylosis.
Primary impaction of permanent teeth most
frequently affects third molars. Lack of
eruption is most often related to crowding and
insufficient maxillofacial development.
Impacted teeth are frequently diverted or
angulated, eventually losing their potential to
erupt; mesioangular, distoangular, vertical,
horizontal and inverted
Localized Disturbances in
Eruption
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Treatment includes long-term observation,
orthodontic-assisted eruption, transplantation, or
surgical removal
Risks associated with both intervention and
nonintervention
Surgical removal of impacted teeth is the
procedure most frequently performed by OMFS
Localized Disturbances in
Eruption
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Ankylosis – cessation of eruption after emergence
Usually develops between ages 7-18; peak 8-9;
prevalence est. 1.3-8.9%
Fails to respond to orthodontic therapy
Failure to treat can result in tilting, carious
destruction, and periodontal disease
When successor tooth present, best treated with
extraction and space maintenance
Localized Disturbances in
Eruption
Primary tooth impaction
Mesioangular impaction
Ankylosis
Developmental Alterations of the
Teeth
Developmental Alterations
in the Number of Teeth
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Anodontia – total lack of tooth development. Rare;
most cases occur in hereditary hypohidrotic
ectodermal dysplasia
Hypodontia – lack of development of one or more
teeth. Uncommon in deciduous teeth, usually
involves mandibular incisors. More common in
permanent teeth, third molars most affected. More
frequent in females than males
Oligodontia – lack of development of six or more
teeth
Developmental Alterations
in the Number of Teeth
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Hyperdontia – development of increased number of
teeth. Additional teeth are supernumerary. Prevalence
1-3%. More common in males and usually develops by
age 20.
Maxilla is most common site (90%) for single tooth
hyperdontia, especially incisor region (mesiodens)
Most single supernumerary teeth are unilateral. Nearly
75% of supernumerary teeth in anterior maxilla fail to
erupt
Non-syndromic multiple supernumerary teeth occur
mostly in mandible.
Hypodontia (oligodontia)
Example of pedigree
Hypodontia in Ectodermal
Dysplasia
Developmental Alterations
in the Number of Teeth
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Mesiodens – supernumerary tooth in maxillary anterior
incisor region
Distomolar/Distodens – accessory fourth molar
Paramolar – posterior supernumerary tooth situated
lingually or buccally to a molar tooth
Dental transposition – normal teeth erupted in an
inappropriate pattern
Natal teeth – teeth present in newborns; teeth arising
during the first 30 days of life; (85% mandibular incisor
region)
Hyperdontia
(supernumeray teeth)
Mesiodens
Cleidocranial dysplasia
Supernumeray premolar
Transposition
(canine-first premolar)
Treatment of Developmental Alterations
in the Number of Teeth
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Hypodontia – often no treatment required for
individual missing teeth; prosthetic replacement for
multiple missing teeth.
Hyperdontia – early removal of accessory tooth;
delayed in therapy can delay eruption of adjacent
teeth or cause displacement.
Natal teeth – may be removed if they are loose; if
stable, they should be retained; Riga-Fede disease
(ulceration of ventral tongue associated with breastfeeding) can often be treated without removal of the
teeth.
Natal teeth
(Riga-Fede syndrome)
Supernumerary teeth
Mesiodens
Mesiodens
Supernumerary premolar
Supernumerary teeth
Supernumerary teeth
Supernumerary teeth in cleidocranial
dysplasia syndrome
Developmental Alterations
in the Size of Teeth
Developmental Alterations in
the Size of Teeth
(1)
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Microdontia – small teeth. Can also be related to
tooth size relative to jaw size. More common in
females. Isolated microdontia within otherwise
normal dentition is not uncommon (peg-shaped
lateral 0.8-8.4%). Diffuse microdontia occurs in
some hereditary disorders and sometimes
associated with hypodontia. Increased in Down’s,
pituitary dwarfism & a few other syndromes.
Macrodontia – larger than average teeth. More
common in males. Typically only a few teeth are
abnormally large. Diffuse macrodontia may occur
in pituitary gigantism. It can be associated with
hyperdontia.
Microdontia
“peg-shaped” laterals
“paramolar”
Developmental Alterations in
the Size of Teeth
(2)
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Macrognathia – normal sized teeth widely
spaced in larger than normal jaw.
Treatment – not necessary except for esthetic
reasons
Developmental Alterations
in the Shape of Teeth
Developmental Alterations
in the Shape of Teeth
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Double teeth – two separate teeth exhibiting union by dentin and
sometimes pulps (fusion).
May result from fusion of two tooth buds, or partial splitting of one
into two.
Concrescence – union of two teeth by cementum without confluence
of dentin.
Gemination – single enlarged tooth or joined (double) tooth in which
tooth count is normal when this tooth is counted as one.
Fusion – single enlarged tooth or joined (double) tooth in which the
tooth count is short one when this tooth is counted as one.
Concrescence
Gemination / Fusion
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Fusion
Gemination
Dilaceration
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Abnormal angulation or bend in root (or
commonly the crown)
During tooth development, it is thought to arise
following displacement injury or less frequently
secondary to the presence of an adjacent cyst or
tumor
Treatment - minor dilaceration in permanent
teeth requires no therapy; grossly deformed
teeth should be removed; extraction of
deciduous teeth when eruption is delayed.
Dilaceration
Supernumerary Roots
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Increased number of roots
No treatment necessary, but detection of extra
root critical for endodontic therapy or exodontia