1. Abnormalities in structure (defective apposition and calcification)
1.1. 1- Defect of Enamel
1.1.1. Hereditary defects ( Amelogenesis imperfecta)
1.1.1.1. affect both decideous and permenant dentition
1.1.1.2. affect either enamel or dentine
1.1.1.3. produce diffuse or verically oriented enamel
1.1.1.4. group of hereditary familial disorders affecting both dentitons
1.1.1.5. Types:
1.1.1.5.1. 1- Hereditary enamel hypoplasia
1.1.1.5.2. 2- Hereditary enamel hypo calcification
1.1.1.5.3. 3- Both types co existing
1.1.2. 2- Acquired defects of enamel
1.1.2.1. caused by local factor
1.1.2.1.1. Trauma
1.1.2.1.2. Infection
1.1.2.1.3. Irradiation
1.1.2.1.4. involving one or two teeth called turner's tooth
1.1.2.2. by generic systemic factor ( Acquired generalized enamel hypoplasia)
1.1.2.2.1. 1- Nutritional deficiencies vitamin A & D calcium and phosphorus
1.1.2.2.2. 2- Exanthematous Fever ( scarlet, measles, chicken pox)
1.1.2.2.3. 3- Hormonal disturbances ( hypothyrodism )
1.1.2.2.4. 4- Infantile GIT disturbances
1.1.2.2.5. 5- Congenital syphilis
1.1.2.2.6. Ingesting chemicals ( fluoride Tetracycline, Cytotoxic drugs)
1.1.2.2.7. Birth injuries and premature birth
1.1.2.2.8. Dental Fluorosis: Mottled Enamel
1.1.2.2.9. Tetracycline Pigmentation
1.1.2.3. affect one dentition usually permenant
1.1.2.4. affect both enamel and dentine
1.1.2.5. while enviromental factors produce horizontally defects corresponding to time and duration
1.2. 2- defects of dentin
1.2.1. 1- dentinogenesis imperfecta ( Hereditary Brown Opalscent Dentine)
1.2.1.1. inherited disorder of dentine formation
1.2.1.2. Classification
1.2.1.2.1. 1- associated with osteogenesis imperfecta
1.2.1.2.2. 2- not associated with osteogenesis imperfecta
1.2.1.3. Clinically
1.2.1.3.1. both decideous and permenant dentitions are affected
1.2.1.3.2. teeth are opalescent with color ranging from bluish gray to brown
1.2.1.3.3. crowns of teeth are smaller than normal with constricted neck and bulbous appearance
1.2.1.3.4. enamel is normal and rapidly loss and teeth shows rapid and severe attrition.
1.2.1.3.5. enamel fracture is due to loss of scalloping of ADJ
1.2.1.3.6. roots are short
1.2.1.3.7. teeth show partial or total obliteration of pulp chambers and root canal with poorly formed dentine
1.2.1.3.8. cementum, periodontal membrane and supporting alveolar bone are appears normal
1.2.1.4. Histological features
1.2.1.4.1. 1- normal enamel
1.2.1.4.2. 2- ADJ is straight rather than scalloped
1.2.1.4.3. 2- mantle dentine is normal
1.2.1.4.4. 3- deep dentine shows
1.2.1.4.5. 4- pulp shows
1.2.2. 2- Shell Teeth ( Dentinogenesis Imperfecta Brandywine type )
1.2.2.1. discovered in brandywine isolate in marylanad us
1.2.2.2. very rare abnormality similar to DI except pulp chamber is not obliterated, dentine is quite thin froming shell around wide pulp
1.2.2.3. early pulp exposure is common sequel of caries affecting these teeth
1.2.2.4. roots are extremely short
1.2.2.5. Histologically
1.2.2.5.1. normal enamel
1.2.2.5.2. peripheral layer of mantle is normal
1.2.2.5.3. dentinal tubules are dilated, less number and missing
1.2.2.5.4. pulp is very wide lacking odontoblastic layer consists of coarse c.t incorprated into the deep surface of dentine
1.2.3. 2- Dentin Dysplasia
1.2.3.1. hereditary disorder of dentine formation
1.2.3.2. Clinical features
1.2.3.2.1. 1- affects decideous and permenant
1.2.3.2.2. 2- crowns are normal in color and shape
1.2.3.2.3. roots are very short and conical
1.2.3.2.4. premature tooth loss may occur early in life because of short roots
1.2.3.2.5. pulps completely obliterated by defective dentine
1.2.3.3. Microscopically
1.2.3.3.1. enamel and subenamel dentine are norml
1.2.3.3.2. deep layer show atypical tubular patterns with amorphous atubular areas and irregular organization
1.2.3.3.3. pulp chambers are obliterated by multiplefused rounded nodules of poorly organized dentine
1.3. 3- Defects of Enamel and Dentine
1.3.1. Regional odontodysplasia ( Ghost Teeth)
1.3.1.1. unkown cause characterized by localized arrest of development of one or more teeth
1.3.1.2. decideous or permenant
1.3.1.3. both enamel and dentine are affected
1.3.1.4. enamel and dentine is very thin pitted pigmented and rough
1.3.1.5. teeth show severe deformed crowns and short formed roots
1.3.1.6. pulp chamber is large
1.3.1.7. affected teeth exhibit a delay or total failure of eruption
1.3.1.8. Radiographically
1.3.1.8.1. marked reduction in radiodensity of enamel and dentine due to lack of adequare calcification
2. Abnormalities in Eruption
2.1. premature eruption
2.1.1. Hereditary
2.1.2. Hyperthyrodism
2.1.3. Facial hemihypertrophy
2.2. delayed eruption
2.2.1. local cause
2.2.1.1. retained dec
2.2.1.2. supernumerary
2.2.1.3. odontome
2.2.2. systemic cause
2.2.2.1. rickets
2.2.2.2. hypothyrodism
2.2.2.3. mongolism
2.3. embedded and impacted teeth
2.3.1. force
2.3.2. space
2.3.2.1. crowding
2.3.2.2. premature loss of decideous
2.4. submerged teeth
3. Abnormalities in number of teeth
3.1. 1- Decrease in number ( defective initiation) ( Anodontia) - Hypodontia
3.1.1. 1- total anodontia
3.1.1.1. associated with hereditary ectodermal dysplasia ( streeter's syndrome)
3.1.1.1.1. hereditary defect in development of ectodermally derived structures
3.1.1.1.2. in majority of cases is it inherited as sex linked and more in males
3.1.1.1.3. clinical features
3.1.1.1.4. Oral manifestations
3.1.1.2. unassociated with hereditary ectodermal dysplasia
3.1.2. 2- partial anodontia or hypodontia ( abscence of single tooth or group of teeth )
3.1.2.1. 1- true anodontia: abscent teeth fail to develop
3.1.2.1.1. failure of development of one or more permenant teeth is common
3.1.2.1.2. 3rd molars then upper lateral then mandibular second premolars bilaterally
3.1.2.1.3. congenitally missing decideous teeth are uncommon but when occuring involve upper lateral
3.1.2.1.4. Etiology
3.1.2.2. 2- Pseudo anodontia: clinically abscent teeth develop but fail to erupt (impacted)
3.1.2.3. false anodontia: tooth loss ( extraction or trauma)
3.2. 2- increase in number
3.2.1. 1- predicideous dentition
3.2.1.1. very rare due to accessory buds being given before formation of enamel organ of decideous teeth
3.2.1.2. small in size present at birth in mandibular incisors and weekly attached to gum
3.2.1.3. they should be distinguished from prematurely erupted decideous teeth which may have erupted at birth
3.2.2. 2- post permenant dentition
3.2.2.1. dentiton formed after permenant
3.2.2.2. enamel organs assumed to arise from dental lamina after giving enamel organ of permenant teeth
3.2.2.3. majority of cases believed to arise from delayed eruption of previously impacted or embedded permenant
3.2.3. 3- supernumerary teeth
3.2.3.1. extra teeth that don't resmeble any adjacent normal teeth
3.2.3.2. more common in maxilla than in mandible and found more often in permenant dentition than primary dentition
3.2.3.3. may be small and conical in shape, single or multiple, erupted or impacted or inverted
3.2.3.4. supernumerary teeth classified according to site to
3.2.3.4.1. Mesiodens
3.2.3.4.2. Distomolar
3.2.3.4.3. Paramolar: on buccal or palatal surface of teeth
3.2.3.5. extra teeth with morphological resemblence adjoining teeth are called supplemental teeth
3.2.3.6. most common site is upper lateral, lower premolar and distal to third molar
3.2.3.7. Etiology
3.2.3.7.1. some supernumerary may have hereditary tendency
3.2.3.7.2. multiple impacted teeth associated with cleidocranial dysostosis and Gardner's syndrome
3.2.3.8. Pathogenesis
3.2.3.8.1. arise from additional tooth germ
3.2.3.8.2. division of the tooth germ of normal series
3.2.3.9. clinical consideration
3.2.3.9.1. additional teeth erupt in abnormal position labial or buccal to the arch and create stagnation areas
3.2.3.9.2. supernumerary tooth may prevent a normal tooth from erupting
3.2.3.9.3. impacted supernumerary teeth develop dentigerous cyst around crown
3.2.4. 4- supplemental teeth
3.3. decideous rarely involved
4. Abnormalities in size of teeth
4.1. 1- Microdontia
4.1.1. 1- True generalized microdontia
4.1.1.1. all teeth in both arches appear smaller than normal
4.1.2. 2- Relative generalized microdontia
4.1.2.1. Normal sized teeth appear small in large jaws
4.1.2.2. Hereditary plays a role
4.1.3. 3- Localized Microdontia involving 1 tooth or group of teeth
4.1.3.1. affects commonly upper lateral peg lateral and third molar
4.1.3.2. unilateral microdontia involving group of teeth
4.2. 2- Macrodontia
4.2.1. 1- True generalized macrodontia
4.2.1.1. all teeth in both arches appear larger than normal
4.2.2. 2- Relative generalized macrodontia
4.2.2.1. normal sized teeth appear large in small jaw
4.2.2.2. hereditary plays a role
4.2.3. 3- Localized Macrodontia involving single or group of teeth
4.2.3.1. most commonly affect upper central, then canine then uppper lateral
5. Abnormalities in Shape
5.1. 1- Gemination
5.1.1. partial division of single tooth germ resulting in tooth with 2 completely or incompletely seperated crowns and single root and root canal
5.1.2. affect decideous and permenant and most common in upper incisor region
5.2. 2- Fusion
5.2.1. results from union of 2 adjacent tooth germs
5.2.2. cause may be hereditary or trauma or crowding
5.2.3. may be complete or incomplete depending on stage of tooth development at time of contact
5.2.3.1. early contact result in fusion of whole tooth later results in union of rrots only
5.2.4. root canals may be seperated
5.2.5. number of tooth reduced ny one except where one of the germs was supernumerary
5.3. 3- Concrescence
5.3.1. type of fusion occuring after root formation is complete
5.3.2. teeth are joined along roots by cementum only
5.3.3. due to trauma or crowding
5.4. 4- Dilaceration
5.4.1. presence of sharp bend along the long axis of tooth
5.4.2. due to trauma during root development
5.4.3. curve may occur anywhere along length of tooth depending on amount of cacified part of tooth when trauma occured
5.5. Supernumerary root
5.5.1. extra roots most common in lower premolars, canines, third molars
5.5.2. may exhibit dilaceration
5.5.3. diagnosed radiographicaly
5.6. Enamel Pearl
5.6.1. small spherical enamel projection on root surface near furcation
5.6.2. common on upper molars
5.6.3. histologically
5.6.3.1. consist of enamel only
5.6.3.2. consist of enamel, dentine and pulp
5.6.4. Pathogenesis
5.6.4.1. due to abnormal displacement of ameloblasts below DEJ junction
5.6.4.2. due to differentiaiton of cells of epithelial root sheath of hertwig into ameloblasts during root formation so nodule forms in place of cementum
5.7. 5- Talon's Cusp (dens evaginatus)
5.7.1. accessory cusp on occlusal surface between buccal and lingual of premolars unilaterally or bilaterally
5.7.2. rare in molars canines and incisors
5.7.3. pulp horn may extend into cusp
5.7.4. pathogenesis
5.7.4.1. due to proliferation and evagination of enamel epithelium and subadjacent mesenchyme during tooth development
5.7.5. Clinical signifacance
5.7.5.1. may contribute to displacement of teeth or pulp exposure with infection following occlusal wear
5.7.6. Talons' Cusp
5.7.6.1. extra cusp resembling eagle talon projecting lingually from cingulum are of incisors extending to incisal edge
5.8. 6- Dens Invaginatus ( dens in Dente)
5.8.1. pathogenesis
5.8.1.1. caused by invagination of all layers of enamel organ to dental papilla during odontogenesis
5.8.1.2. result in forming of enamel lined cavity communicating with surface
5.8.1.3. radio
5.8.1.3.1. tooth like structure in the pulp of tooth
5.8.1.4. clinically
5.8.1.4.1. may be normal shaped or malformed exhibiting deep pit or cervice in area of cingulum
5.8.1.5. forms
5.8.1.5.1. mild form
5.9. 7- Taurodontism
5.9.1. means bull like teeth as teeth are similar to teeth of ungulate animals
5.9.2. variation of tooth form where there is enlargement of trunk on expense of roots; furcation is located more apically
5.9.3. Classification
5.9.3.1. 1- hypotaurodontism
5.9.3.2. 2- Mesotaurodontism
5.9.3.3. 3- Hypertaurodontism; extrem form where furcation occur at apex of roots
5.9.4. Pathogeneis
5.9.4.1. due to failure of wpithelial root sheath of `Hertwig to invaginate at proper horizontal level to form furcation area
5.9.5. Clinically
5.9.5.1. 1- tooth have no unusual morpholigical clinical features
5.9.5.2. affect permenant and decideous
5.9.5.3. may be unilateral or bilateral affectin 1 or group of teeth
5.9.5.4. most common in molars
5.9.6. Radio
5.9.6.1. involved teeth are rectangular in shape
5.9.6.2. pulp chamber is extremely large with greater apico occlusal height
5.9.6.3. pulp lack cervical constriction
5.9.6.4. furcation is apically displaced and roots are short
5.10. 8- Congenital Syphilis
5.10.1. it is a contagious venereal disease caused by spirochete treponema pallidum
5.10.2. prenatal syphilis transmitted from infected mother to fetus via placenta
5.10.3. children born show abnormality in shape size strucure and number of teeth
5.10.4. decideous is normal because it develop ealy on if fetus is infected at early stage usually abortion occurs
5.10.5. most commonly affect centrals and 6 less frequently lateral and canine
5.10.6. due to infection of tooth germ by spirochetes causing distortion of ameloblastic layer
5.10.7. Hutchinsons teeth
5.10.7.1. central is barrel shape mesial and distal surface taper toward incisal edge giving screw driver appearance
5.10.7.2. incisal edge have central notch
5.10.7.3. mesial and distal angles are rounded
5.10.7.4. may show enamel hypoplasia
5.10.8. Moons's
5.10.8.1. constricted occlusal surface and rounded angles and is dome shaped
5.10.9. mulberry
5.10.9.1. occlusal surface is rough, pitted and exhibit irregular tubercles replacing normal cusp pattern ( mullberry)