ch 5: developmental abnormalities of teeth

types of abnormalities in the number of teeth

-Anodontia

-Hypodontia

-Supernumerary teeth

anodontia

-The congenital lack of teeth

-May be associated with ectodermal dysplasia

total anodontia

lack of all teeth (rare)

hypodontia

-The lack of one or more teeth

-Rather common

-The most common missing permanent teeth are:

• Mandibular and maxillary third molars

• Maxillary lateral incisors

• Mandibular second premolars

-The most common missing deciduous tooth is the mandibular incisor

oligodontia

-Subcategory of hypodontia

-Six or more teeth are congenitally missing (not including third molars)

-Tends to be genetic

-May be a component of a syndrome: Down’s syndrome, Ectodermal Dysplasia, Gorlin syndrome

-Treatment: May require prosthetic replacement and or Orthodontic evaluation and treatment may be necessary

supernumerary teeth

-Extra teeth

-May result from formation of extra tooth buds in the dental lamina or from the cleavage of already existing tooth buds

-May occur in either deciduous or permanent dentition

-Most often seen in the maxilla

-Treatment: Erupted teeth may require removal if they cause crowding, malposition of adjacent teeth, or noneruption of normal teeth; Nonerupted teeth should be extracted because a risk exists for cyst development around the crown

-Multiple supernumerary teeth may be associated with Cleidocranial Dysplasia or Gardner syndrome

mesiodens

-The most common supernumerary tooth

-Located between the maxillary incisors

-May be inverted when seen on radiographs

distomolar or distodens

-The second most common supernumerary tooth

-Located distal to the third molar

types of abnormalities in the size of the teeth

-microdontia

-macrodontia

microdontia

-One or more teeth is (are) smaller than normal

-involving a single tooth is far more common

-Maxillary lateral incisor (peg laterals) and maxillary third molar are the most commonly involved teeth

true generalized microdontia

-seen in down’s syndrome and a pituitary dwarf

-all teeth are smaller than normal

generalized relative microdontia

normal-size teeth appear small in a large jaw

macrodontia

-one or more teeth are larger than normal

-affecting a single tooth is uncommon

true generalized macrodontia

seen in cases of pituitary gigantism

relative generalized macrodontia

large teeth in a small jaw (micrognathia)

types of abnormalities in the shape of teeth

-Gemination

-Fusion

-Concrescence

-Dilaceration

-Enamel pearl

-Talon cusp

-Taurodontism

-Dens in dente

-Dens evaginatus

-Supernumerary roots

gemination

-Uncommon, occurs when a single tooth germ attempts to divide in two

-Appears as two crowns joined together by a notched incisal area

-Radiographically, usually one single root and one common pulp canal exists

fusion

-The union of two normally separate adjacent tooth germs

-Appears as a single large crown that occurs in place of two normal teeth

-May be complete or incomplete fusion, Incisors are the teeth most often affected

-Radiographically, either separate or fused roots and root canals are seen

-The patient is usually short one tooth

hypercementosis

-Excessive cementum on the roots of the teeth

-Occurs in adults; incidence and amount increase with age

-Feature associated with several local and systemic factors: frequently seen in Paget’s disease of the bone

-No treatment necessary

concrescences

-Two adjacent teeth are united by cementum

-Though to be caused by crowding or trauma that results in close approximation of adjacent tooth roots. Subsequent cementum deposition acts to fuse the 2 adjacent roots.

-Usually discovered on radiograph

dilaceration

-It is a sharp curve or angle in the root, and less common, in the crown

-May be caused by trauma to the tooth germ during root development or idiopathic

-Usually discovered on radiograph

-May cause a problem if the tooth must be removed or a root canal performed

enamel pearl

-A small, spherical enamel projection on a root surface

-Usually found on maxillary molars

-Radiographically, it appears as a small, spherical radiopacity

-Removal may be necessary if periodontal problems occur in the furcation

talon cusp

-An accessory cusp located in the cingulum area of a maxillary or mandibular permanent incisor

-Contains a pulp horn

-May interfere with occlusion

taurodontism

-Uncommon

-Clinically is crown appears normal

-Radiographically, characteristic appearance of radiolucent stretched, enlarged, elongated pulp chamber without constriction at the CEJ

-Roots appear short with furcation near the apex.

-May occur in both deciduous and permanent dentition

-Identified on radiographs

-No treatment

-Seen in conditions like Down’s syndrome and others

dens invaginatus

-Occurs when the enamel organ invaginates into the crown of a tooth before mineralization

-2 forms coronal and radicular (rare)

-Seen more often in Maxillary lateral incisors

-Radiographically, it appears as a toothlike structure within a tooth “dens in dente”. Elongated bulb or pear shaped mass of enamel within dentin

-Vulnerable to caries, pulpal infection, and necrosis, due to communication with the oral cavity via the pit.

-Non vital teeth may be treated endodontically

dens evaginatus

-aka central tubercle, occlusal pearl, accessory tubercle

-An accessory enamel cusp found on the occlusal tooth surface

-Clinically, appears as a small, rounded lobe of enamel between the buccal and lingual cups

-Most often seen on mandibular premolars

-May cause occlusal problems

supernumerary roots

-May involve any tooth

-Most commonly, maxillary and mandibular third molars if multirooted teeth are involved. Single rooted teeth most commonly affected are the mandibular bicuspids and cuspids

-May become clinically significant if removal or endodontic treatment is necessary

types of abnormalities of tooth structure

-Enamel hypoplasia

-Enamel hypocalcification

-Endogenous staining of teeth

-Regional odontodysplasia

enamel hypoplasia

-The incomplete or defective formation of enamel, resulting in the alteration of tooth form or color

-Results from a disturbance or damage to ameloblasts during enamel matrix formation

enamel hypoplasia may be dure to many factors including:

-Amelogenesis imperfecta

-Febrile illness (measles, chickenpox, scarlet fever)

-Vitamin deficiency

-Infection of a deciduous tooth

-Ingestion of fluoride

-Congenital syphilis

-Birth injury, premature birth

-Idiopathic factors

Enamel Hypoplasia Caused by Febrile Illness or Vitamin Deficiency

-Ameloblasts are one of the most sensitive cell groups in the body

-Any serious systemic disease or severe nutritional deficiency can produce enamel hypoplasia

-Febrile illness (chickenpox, measles, scarlet fever) and vitamin deficiency (A, C, D) that occur during the time of tooth formation can result is in pitting of the enamel (a type of enamel hypoplasia)

-Only the crowns of the teeth being developed during the febrile illness or vitamin deficiency are affected

Enamel Hypoplasia Resulting from Local Infection or Trauma

-Enamel hypoplasia of an adult tooth may result from infection of a deciduous tooth

-A single tooth is usually affected; it is referred to as a Turner tooth

-The color of the enamel may range from yellow to brown, or severe pitting and deformity may be involved

-The severity of the defect depends on severity of deciduous tooth infection, the degree of periapical tissue involvement and the stage of development of the underlying permanent tooth

Enamel Hypoplasia Resulting from Fluoride Ingestion

-Dental Fluorosis

-Affected teeth exhibit a mottled discoloration of enamel (irregular areas of discoloration)

-Ingestion of water with two to three times the recommended amount of fluoride leads to white flecks and chalky opaque areas of enamel

-Four times the recommended amount of fluoride causes brown or black staining, pitted or overall corroded appearance

-All permanent teeth are affected, generally these teeth are decay resistant

Enamel Hypoplasia Resulting from Congenital Syphilis

-transmitted from an infected mother to her fetus via the placenta

-Results in enamel hypoplasia of the permanent incisors and first molar

-hutchinson incisors

-mulberry molars

hutchinson incisors

shaped like screwdrivers: broadest at middle third and narrow incisally with a notched incisal edge

mulberry molars

have a berrylike appearance; first molars appear as irregularly shaped with a narrow occlusal surface made up of tiny globules instead of cusps

Enamel Hypoplasia Resulting from Birth Injury, Premature Birth, or Idiopathic Factors

-Enamel hypoplasia may occur as a result of trauma or injury at the time of birth

-Even a mild illness or systemic problem can result in enamel hypoplasia

-Ameloblasts are sensitive cells that are easily damage

enamel hypocalcification

-A developmental anomaly resulting in a disturbance in the maturation of the enamel matrix

-Unknown cause, trauma during maturation of enamel matrix has been suggested

-Usually appears as a chalky, white spot on the middle third of smooth crowns

-The underlying enamel may be soft and susceptible to caries

Endogenous (intrinsic) Staining of Teeth

The result of deposition of substances circulating systemically during tooth developmen

endogenous staining of teeth may be due to:

-Tetracycline stain

-Erythroblastosis fetalis: Rh incompatibility

-Neonatal liver disease

-Congenital porphyria: An inherited metabolic disease

Regional Odontodysplasia

-aka ghost teeth

-Unusual, one or several teeth in the same quadrant are malformed

-Cause is idiopathic, changes in the vascular supply during development is the most accepted theory

-Exhibit a marked reduction in radiodensity and a characteristic ghostlike appearance

-Very thin enamel and dentin, with an enlarged pulp

-Affects both dentitions

-The teeth do not erupt or eruption is incomplete, if it does erupt it is nonfunctional

-Usually treated by extraction

types of abnormalities of tooth eruption

-Impacted teeth cannot erupt because of a physical obstruction

-Embedded teeth do not erupt because of lack of eruptive force

-Ankylosed teeth

impacted and embedded teeth

-Any tooth can be impacted

-Third-molar impactions are classified according to the position of the tooth: mesioangular, distoangular, vertical and horizontal

-Teeth can be completely impacted in bone or they may be partially impacted

-Partially impacted teeth are prone to infection: pericoronitis

-Impacted teeth may be surgically removed to prevent odontogenic cyst and tumor formation or damage to adjacent teeth

-The optimal time is between 12 and 24 years of age

ankylosed teeth

-Tooth cementum fused to bone

-Prevents exfoliation of the deciduous tooth and eruption of the underlying adult tooth

-The ankylosed deciduous tooth appears submerged, below occlusal plane and has a different sound when percussed (a kind of dull thud)

-The periodontal ligament space is lacking

-Difficult to extract