1. number of teeth
1.1. Anodontia
1.1.1. True anodontia
1.1.1.1. congenital absence ALL of teeth.
1.1.1.2. both deciduous and permanent dentition.
1.1.1.3. associated with hereditary ectodermal dysplasia.
1.1.2. Induced or false anodontia
1.1.2.1. result of extraction of all teeth.
1.1.3. Pseudo-anodontia
1.1.3.1. applied to multiple, unerupted teeth.
1.1.4. Hypodontia
1.1.4.1. lack of development of one or more teeth.
1.1.4.2. Syndromes associated
1.1.4.2.1. Ankyloglossia superior
1.1.4.2.2. Crouzon
1.1.4.2.3. Down
1.1.4.2.4. Ectodermal dysplasia
1.1.4.2.5. Ehlers danlos
1.1.4.2.6. Hurlers
1.1.4.2.7. Turner
1.1.5. Oligodontia
1.1.5.1. Lack of development of six or more teeth.
1.1.5.2. bilateral absence of corresponding teeth.
1.1.6. Etiology
1.1.6.1. Familial tendency
1.1.6.2. Missing third molars
1.1.6.3. hereditary ectodermal dysplasia
1.1.6.3.1. few teeth that are present may be deformed or cone shaped.
1.1.6.4. Xray radiation
1.1.7. C/F
1.1.7.1. involved teeth
1.1.7.1.1. Third molars (all the 4 may be missing)
1.1.7.1.2. Max lat incisors
1.1.7.1.3. Max+Mand 2nd premolar
1.1.7.2. Bilateral involvement
1.2. Hyperdontia (Supernumerary teeth)
1.2.1. Development of an increased number of teeth
1.2.2. may closely resemble the teeth of the belonging group
1.2.2.1. may have no resemblance
1.2.3. Etiology
1.2.3.1. develops from a third tooth bud
1.2.3.1.1. form the dental lamina near the permanent tooth bud.
1.2.3.2. splitting of the permanent bud itself
1.2.3.3. Hereditary tendency.
1.2.4. C/F
1.2.4.1. found in any location.
1.2.4.2. 90% of occurrence is in the maxilla.
1.2.4.3. May be erupted or impacted.
1.2.5. Classification
1.2.5.1. on their location
1.2.5.1.1. Mesiodens
1.2.5.1.2. Distomolar/distodens
1.2.5.1.3. Paramolar
1.2.5.2. on size & shape
1.2.5.2.1. Supplemental
1.2.5.2.2. Rudimentary
1.2.6. Syndromes associated
1.2.6.1. Cleidocranial dysplasia
1.2.6.2. Gardner
1.2.6.3. Crouzon
1.2.6.4. Down
1.3. Pre-deciduous teeth
1.3.1. Infants born with structures appearing to be erupted teeth in the mandibular incisor region.
1.3.2. from an accessory bud of the dental lamina
1.3.3. hornified, epithelial structures without roots.
1.3.4. Occurs in the gingiva over the crest of the ridge.
1.3.5. May be easily removed.
1.3.6. Differentiated from true deciduous teeth or natal teeth
1.4. Post-permanent dentition
1.4.1. all their permanent teeth extracted and yet had subsequently erupted several more teeth
1.4.2. due to delayed eruption of retained/embedded teeth.
1.4.3. Called third dentition.
1.4.3.1. multiple supernumerary unerupted teeth.
1.4.4. develops from a bud of the dental lamina beyond the permanent tooth germ.
2. Size of teeth
2.1. Microdontia
2.1.1. smaller than normal
2.1.1.1. True generalised
2.1.1.1.1. All teeth small
2.1.1.1.2. Rare
2.1.1.1.3. Well formed but small
2.1.1.1.4. Seen in Pituitary dwarfism, Down’s syndrome. .
2.1.1.2. Relative generalised
2.1.1.2.1. Normal/slightly smaller
2.1.1.2.2. Inheritance of jaw size from one parent and tooth size from other parent can lead to this variations.
2.1.1.3. Involving single tooth(localised)
2.1.1.3.1. maxillary lateral incisor +3rdM
2.1.1.3.2. Supernumerary teeth are small in size.
2.1.1.3.3. seen in Facial hemiatrophy.
2.2. Macrodontia[megalodontia or megadontia.]
2.2.1. larger than normal.
2.2.1.1. True generalised
2.2.1.1.1. Extremely rare.
2.2.1.1.2. All the teeth are larger
2.2.1.1.3. Seen w/t pituitary gigantism.
2.2.1.2. Relative generalized macrodontia
2.2.1.2.1. more common.
2.2.1.2.2. Normal or slightly larger
2.2.1.2.3. Hereditary factors.
2.2.1.3. single teeth
2.2.1.3.1. uncommon + Unknown etiology.
2.2.1.3.2. normal in every aspect except,its size.
2.2.1.3.3. Should not confused with fusion of teeth.
2.2.1.3.4. seen in facial hemi-hypertrophy of the face
3. shape of teeth
3.1. Gemination
3.1.1. arise from attempt at division of single tooth germ by invagination.
3.1.1.1. resultant incomplete formation of two teeth.
3.1.2. Hereditary factors
3.1.3. Difficult to differentiate this from fusion of a normal and supernumerary tooth.
3.1.4. C/F
3.1.4.1. in deciduous and permanent teeth.
3.1.4.2. Structure formed is of one tooth with
3.1.4.2.1. Two completely or incompletely separated crowns.
3.1.4.2.2. Roots are single with a root canal
3.1.4.3. Twinning
3.1.4.3.1. designate the production of equivalent structures by division
3.1.4.3.2. resulting in one normal and one supernumerary tooth.
3.2. Fusion
3.2.1. Type (based on the stage of tooth development at the time of fusion.)
3.2.1.1. Complete
3.2.1.2. Incomplete
3.2.2. contact of developing teeth and their subsequent fusion.
3.2.2.1. By Physical force or pressure
3.2.2.2. If contact occurs before calcification
3.2.2.2.1. two teeth may be completely united to form a single large tooth.
3.2.2.2.2. Dentin is confluent in true fusion.
3.2.2.3. If contact occurs after calcification
3.2.2.3.1. roots may be united.
3.2.3. arise through union of two normally separated tooth germs.
3.2.3.1. between two normal teeth or a normal tooth with a supernumerary tooth like mesiodens or distomolar.
3.2.4. C/F
3.2.4.1. Tooth may have separate or fused root canals.
3.2.4.2. Common in deciduous as well as permanent
3.2.4.3. Clinical problems
3.2.4.3.1. include esthetics, spacing and periodontal conditions.
3.3. Concrescence
3.3.1. form of fusion which occurs after root formation has been completed.
3.3.2. Teeth are united by cementum only. Due to :
3.3.2.1. Traumatic injury.
3.3.2.2. Crowding of teeth
3.3.3. C/F
3.3.3.1. occur before or after tooth eruption.
3.3.3.2. involves two teeth
3.3.3.2.1. But a case involving three teeth has been reported.
3.3.3.3. Diagnosed by
3.3.3.3.1. radiographic examination.
3.3.3.4. Should be noted during extraction procedures. .
3.3.4. Histopathology
3.3.4.1. Deposition of excessive cementum over the original layer of primary cementum.
3.3.4.2. hypocellular
3.3.4.2.1. Or exhibit areas of cellular cementum resembling bone called osteocementum.
3.3.4.3. Polarized light to differentiate dentin and cementum.
3.3.5. Factors
3.3.5.1. Local
3.3.5.1.1. Abnormal occlusal trauma
3.3.5.1.2. Adjacent inflammation
3.3.5.1.3. Unopposed teeth
3.3.5.2. Systemic
3.3.5.2.1. Acromegaly and pituitary gigantism
3.3.5.2.2. Arthritis
3.3.5.2.3. Calcinosis
3.3.5.2.4. Paget’s disease
3.3.5.2.5. Rheumatic fever
3.4. Dilaceration
3.4.1. angulation or a sharp bend or curve, in the root or crown of a formed teeth.
3.4.2. Etiology
3.4.2.1. Dilaceration (permanent tooth)
3.4.2.1.1. traumatic injury(avulsion or intrusion) to the deciduous predecessor
3.4.2.2. secondary to adjacent cyst, tumor, odontogenic hamartoma.
3.4.3. C/F
3.4.3.1. curve or bend
3.4.3.1.1. occur anywhere along the length of the tooth
3.4.3.2. Can be problematic during extractions
3.4.3.2.1. need for pre-operative radiographs.
3.5. Cusp of Carabelli
3.5.1. Accessory cusp located on palatal aspect of mesiopalatal cusp of maxillary molars.
3.5.2. Most pronounced on
3.5.2.1. 1st M
3.5.3. less obvious on
3.5.3.1. 2nd & 3rd molars
3.5.4. High prevalence in Caucasian whites & least among Asians.
3.6. Talon cusp
3.6.1. eagle’s talon,
3.6.2. projects lingually from the cingulum areas of a maxillary or mandibular permanent incisor.
3.6.3. blends smoothly with the lingual tooth
3.6.3.1. except for a deep developmental groove.
3.6.4. C/F
3.6.4.1. uncommon among the general population.
3.6.4.2. seen in other somatic and odontogenic anomalies.
3.6.4.3. Clinical problems
3.6.4.3.1. esthetics, caries control and occlusal accomodation.
3.6.5. More prevalent in
3.6.5.1. Rubinstein – Taybi syndrome.
3.7. Dens evaginatus
3.7.1. Leong’s premolar, Evaginated odontome.
3.7.2. accessory cusp or a globule of enamel on the occlusal surface between the buccal and lingual cusps of premolars
3.7.2.1. unilaterally
3.7.2.2. bilaterally
3.7.3. Etiology
3.7.3.1. mongoloid ancestry – chinese, japanese, filipinos, eskimos and american-indians.
3.7.3.2. proliferation and evagination of an area of the inner enamel epithelium
3.7.4. C/F
3.7.4.1. physically resemble talon cusp.
3.7.4.2. Extra cusp can lead to
3.7.4.2.1. Incomplete eruption
3.7.4.2.2. Displacement of teeth
3.7.4.2.3. Pulp exposure
3.8. Dens invaginatus
3.8.1. Dens in dente,Dilated composite-odontome.
3.8.2. result of invagination in the surface of a tooth crown before calcification has occurred.
3.8.3. invaginated tooth which appeared radiographically as a tooth within a tooth.
3.8.3.1. it is a misnomer but continued to be used.
3.8.4. Etiology
3.8.4.1. Increased localized external pressure
3.8.4.2. Focal growth retardation
3.8.4.3. Focal growth stimulation
3.8.5. C/F
3.8.5.1. most frequently involved
3.8.5.1.1. Permanent maxillary lateral incisors
3.8.5.2. sometimes
3.8.5.2.1. maxillary central incisor and some posterior teeth.
3.8.5.3. Frequently bilateral.
3.8.6. coronal dens invaginatus types
3.8.6.1. Mild form
3.8.6.1.1. accentuation/deep invagination in lingual pit area.
3.8.6.2. Radiographs reveal
3.8.6.2.1. pear shaped invagination of enamel and dentin
3.8.6.3. Severe form
3.8.6.3.1. nearly to the apex of the root.
3.8.7. Radicular dens invaginatus
3.8.7.1. results from infolding of hertwig’s sheath and origin is within the root after development complete.
3.8.7.2. Food debris can accumulate
3.8.7.3. Bizarre radiographic
3.8.7.4. detected in radiographs even before the tooth erupts.
3.9. Taurodontism
3.9.1. bull-like tooth as it is similar to teeth in ungulate or cud-chewing animals.
3.9.2. enlargement of the body and pulp chamber of a multi- rooted tooth
3.9.3. Classification
3.9.3.1. Hypotaurodont
3.9.3.1.1. mildest form
3.9.3.2. Mesotaurodont
3.9.3.2.1. moderate
3.9.3.3. Hypertaurodont
3.9.3.3.1. severe form with furcation
3.9.4. Etiology
3.9.4.1. failure of Hertwig’s epithelial sheath to invaginate at the proper horizontal level.
3.9.4.2. genetically controlled and familial in nature.
3.9.4.3. amelogenesis imperfecta -hypomaturation-hypoplastic variety.
3.9.5. C/F
3.9.5.1. deciduous or permanent teeth
3.9.5.1.1. more common in permanent teeth).
3.9.5.2. Usually molars
3.9.5.2.1. single/multiple.
3.9.5.3. Unilateral or bilateral involvement.
3.9.5.4. No unusual morphology.
3.9.5.5. rectangular shape
3.9.5.6. Large pulp chamber+short root
3.9.5.7. Furcation near to root apice
3.9.6. Syndromes associated
3.9.6.1. Ectodermal dysplasia
3.9.6.2. Hyper/Hypophosphatasia -
3.9.6.3. Oculo-dental-digital dysplasia
3.9.6.4. Tricho-dento-osseous syndrome
3.9.6.5. Down’s syndrome
3.10. Supernumerary roots
3.10.1. increased number of roots on a tooth
3.10.2. involve any tooth.
3.10.3. Mandibular cuspids and bicuspids may have two roots.
3.10.4. Maxillary and mandibular molars may exhibit additional roots.
3.11. Ectopic enamel
3.11.1. presence of enamel in unusual locations,
3.11.1.1. mainly in the roots of teeth.
3.11.2. known as enamel pearls.
3.11.3. Project from the surface of the root.
3.11.4. Hemispheric structures
3.11.4.1. Entirely of enamel,
3.11.4.2. Enamel, dentin and pulp tissue.
3.11.5. Cervical enamel extensions also occur along the root surface.