Developmental anomalies of the teeth, specific and non – specific disorders of hard dental tisuess 6 DM

Developmental anomalies of the teeth, specific and non –

specific disorders of hard dental tisuess

6 DM

Developmental anomalies

- tooth development is strict under genetic control

- disturbances in tooth development result from gene mutation

- tooth development may be disturbed at different stages of morphogenesis

- definitive result depends on the timing and the type of insult


Disturbances in tooth development:

numerical variations (missing or supernumerary teeth)

variations in size of teeth

variations of shape of teeth

disturbances in eruption


Numerical variations

1.Hypodontia

- number of teeth is decrease

- the most commonly missing teeth are:

the third molars, second premolars, maxillary lateral incisors

- oligodontia, anodontia, agenesis



1.Hypodontia in deciduous dentiotion:

- prevalence 0.1 – 0.7%

- central incisors

- oligondontia and anodontia is rare, may be found in connection with ectodermal dysplasia


Ectodermal dysplasia:

- describes a group of developmental, often inherit, disorders involving the ectodermally structures(hair,teeth, nails, skin and sweat glands)

- presentation:multiple missing teeth, fine, sparse hair, dry skin, maxillary hypoplasia, eversion of the lips, pigmentation around the mounth and eyes. The teeth are conical, small, often with a large diastema.



1.Hypodontia in permanent dentiotion:

- prevalence 6 – 10%

- usually affects 2 or more teeth in 50% of the cases

- often occures symmetrical hypodontia

- particular relation with the microdontia


Solitary median maxillary central incisor syndrome

- is very rare

- midline symetrical maxillary central incisor

- can be associated with cleft palate, choanal stenosis, umbilical hernia, hypoplasia of sella turcica, pituitary dysfunction, growth hormone deficiency



2. Hyperodontia

- number of the teeth is increse

- is quite rare as hypodontia

Frequency: primary teeth 0,3 - 0,8%

permanent teeth 1,0 – 3,5%



2. Hyperodontia

- shape is conical or normal

- supernumerary teeth can erupt or cause anomalous eruption of neighbouring teeth

- most frequent is mesiodens

- part of syndrom cleidocranial dysplasia


Cleidocranial dysplasia:

- short stature

- aplasia or hypoplasia of clavicles

- delayed ossification

- delayed eruption of teeth

- dentigerous cyst formation


a) Dentes praelactales

- frontal region in a newborns

- no roots

Th: extraction


Variations in tooth size:

1. Macrodontia

- teeth are larger than normal

- true macrodontia involving the whole dentition

2. Microdontia

- one or more teeth are smaller than normal

- most affect the maxillary third molars

General microdontia: is a rare conditionoccuring in connection with congenital

Local microdontia: involving single teeth, associated with hypodontia

3. Rhizomicry

-lenght of the root is shorter than the height of the crown

-connected with osteoporosis

- predominantly affecting maxillary incisors and premolars


Variations on tooth shape

1. Dens invaginatus

- malformation due to an invagination of enamel epitelium resulting in a chanel or lumen surrounded by hard tissues within the tooth. The anomaly occurs most frequently in the palatal surface of max. lateral incisor.

2. Conical peg-shaped tooth



3. Taurodontism

- elongated root- stem with the furcation more apical than normally

4. Double formation of teeth

a) concrescence- two normal appearing crowns are present and the fusion involves only the cementum



b) Fusion – union in dentin and/or enamel between two or more normal teeth

c) Gemination – incomplete division of a tooth germ or a union between normal and a supernumerary tooth

5. Dnes evaginatus

- is an extra cusp, usually in the central groove or ridge of a posterior teeth and in the cingulum of the central or lateral incisor


6. Dens in dente

- is a condition resulting from invagination of the inner enamel epithelium producing the appearance of a tooth within a tooth

7. Dilaceration

- an abnormal bend of the rooth during its development and is thought to result from a traumatic episode


Variations in tooth eruption

a) tooth retention

b) tooth semiretention

c) anomalous position after eruption

Non – specific disorders of hard dental tisuess

1) Hypoplasia

2) Hypomineralization

Hypoplasia:

Ethiology:- metabolic disorders, fever, endocrinic disease,trauma, inflammation

Cl. picture: anomalous shape of dental crown, grooves and fissures, color-dark brown, yellowbrown.

Non – specific disorders of hard dental tisuess

Hypomineralization:

Ethiology:- metabolic disorders, fever, endocrinic disease,trauma, inflammation

Cl. picture: normal shape of dental crown, in hard dental tisuess are quality changes. Color- white or brown smudges, localization on labial surfaces of incisors

Specific disorders of hard dental tisuess

Dysplasia of hard dental tisuess

1.DENTIN DYSPLASIA

Ethiology: ingestion of chemicals, prematurity birthweight, severe malnutrition, bilirubinemia

Typ I: radicular dentin dysplasia or rootless tooth

Typ II: anomalous dysplasia of dentin with frequent discoloration of primary teeth, permanent teeth often appear normal clinically but have thistle-tube formed pulp chamber. Pulp stones may occure.


2. Fluoride induced defect


3. Tetracycline defects

- TTC has a strong affinity to mineralized tisuess, primary to dentin and bones

- dentin defects are persistent

- discolored horizontal bands may appear gray, bluish

- discolored enamel has some translucency left

- this ATB shoud not be prescribed to children below the age of 8, pregnant women, lactating mothers


4. Molar – incisor hypomineralization

- demarcated opacities in the perm. first molars, perm. incisors are often also involved

- may affect one or all molars and one or more incisors

- creamy white spot to yelowish brown discoloration

- defect are porous


Subj. symptoms:

- shooting pain during brushing teeth or breathing cold air

Ethiology:

- unknown, but suggestion are: medical problem related to birth, respiratory diseases during first 3 years of life


Amelogenesis imperfecta

Definition:AI represents a roup of condition, genomic in origin, which affect the structure and clinical appearance of the enamel of all or nearly all teeth in a more or less equal manner, and which may be associated with morphologic or biochemical changes elsewhere in the body.


- autosomal dominant, autosomal recessive

- incidence 1 in 14 000

- 4 major categories, 14 subtypes

General manifestation:

- normal intelligence, good general health

Craniofacial/dental manifestation:

- enamel defect that affects both dentitions, appearance is yellowbrown to orange depending on subtyp


Typ I:- hypoplastic (occuring in the histodifferation stage of tooth development, insufficient quantity of enamel is formed)

TypII:- hypomaturation (defect of in enamel matrix apposition)

Typ III:- hypocalcified (enamel is normal, but qualitatively the matrix is poor calcified with a resultant fracturing of the enamel surface. Hypocalcified enamel is soft and fragile, especially at the incisal region, and is easily fractured, exposing dentin.


Typ IV:- hypomaturation, hypoplastic with taurodontism (the enamel appears mottled with a yellow-brown color and is pittedon the facial surfaces. Molar teeth demonstrate taurodontism.


Dentinogenesis imperfecta

Defect of predentin matrix that result amorphic, disorganized, and atubular circumpulpal dentin.

- incidence 1 in 8000

- 3 basic types

Shields type 1

Shields type 2

Shields type 3


Shields type 1

- occurs with AI

- inherit defect in collagen formation

- osteoporotic brittle bones

- bowing of the lips

- blue sclera

- bitemporal bossing

- obliteration of pulp chamber,periapical radiolucencies, bulbous crowns, root fractures


Shields type 2

- hereditary opalescent dentin

- autosomal dominant

- affect primary and permanent dentition

Shields type 3

- is rare, bell-shaped crown,

- it has occured exclusively in a triracial isolated group in Maryland



Documents

Developmental anomalies of the teeth, specific and non – specific disorders of hard dental tisuess 6 DM