Abnormalities of Teeth Part 2

Microdontia

Unusually small teeth; more common in females, associated with hypodontia

Relative microdontia

Normal-sized teeth that appear small because the jaw/maxilla is larger than normal

Diffuse true microdontia

All teeth affected; seen in Down syndrome, pituitary dwarfism, rare hereditary disorders

Most common tooth for isolated microdontia

Maxillary lateral incisor (peg-shaped crown, normal root)

Isolated microdontia inheritance pattern

Autosomal dominant with incomplete penetrance

Macrodontia

Teeth larger than normal

Relative macrodontia

Normal-sized teeth in a small jaw; can cause crowding and impaction

Diffuse macrodontia causes

Pituitary gigantism, pineal hyperplasia with hyperinsulinism, hemifacial hypertrophy

Gemination

A single enlarged/joined tooth where tooth count is NORMAL when the anomalous tooth is counted as one

Gemination location

Anterior maxilla most common; bilateral is less frequent

Fusion

A single enlarged/joined tooth where tooth count reveals a MISSING tooth when the anomalous tooth is counted as one

Fusion location

Anterior maxilla most common; bilateral less frequent

Concrescence

Union of two adjacent teeth by cementum alone, WITHOUT confluence of underlying dentin

Concrescence common cause

Post-inflammatory, usually in large carious molars with periapical pathosis (posterior maxilla most common)

Turner's hypoplasia

Enamel defects on a permanent tooth caused by periapical inflammatory disease of the overlying deciduous tooth

Turner's tooth

The affected permanent tooth resulting from Turner's hypoplasia

Determining factors of Turner's hypoplasia severity

Stage of tooth development, length of time infection remains untreated, virulence of organism, host resistance, traumatic injury

Turner's hypoplasia most commonly affects

Permanent bicuspids (premolars), since they sit next to primary molars that get infected

Syphilitic hypoplasia

Dental changes due to congenital syphilis; currently very rare; causes enamel hypoplasia

Hutchinson's teeth

Anterior teeth shaped like straight-edge screwdrivers with a central notch on the incisal edge (from congenital syphilis)

Mulberry molars

Molars with constricted occlusal table and disorganized surface anatomy resembling a mulberry (from congenital syphilis)

Talon cusp

Well-delineated additional cusp on an anterior tooth extending at least half the distance from the CEJ to the incisal edge

Talon cusp most common location

Maxillary lateral incisor

Talon cusp genetic influence

Documented in twins

Talon cusp permanent teeth distribution

55% maxillary lateral, 33% maxillary central, 6% mandibular incisors, 4% maxillary canine

Talon cusp associated with

Supernumerary teeth, odontoma, impacted teeth, peg-shaped lateral incisors, syndromes (Mohr, Rubinstein-Taybi, Sturge-Weber)

Ankylosis

Cessation of eruption after emergence due to anatomic fusion of cementum with alveolar bone

Ankylosis cause

Unknown; may be trauma, injury, chemical/thermal irritation

Ankylosis other terms

Infraocclusion, secondary retention, submergence, reimpaction, reinclusion

Ankylosis etiology factors

Disturbed local metabolism, trauma, genetically decreased PDL gap, disturbed root resorption/repair, genetic predisposition

Ankylosis most common tooth

Primary first molar, mandible

Ankylosis X-ray finding

Absence of periodontal ligament space

Dens invaginatus (dens in dente)

Deep surface invagination of the crown or root lined by enamel; two types: coronal and radicular

Coronal dens invaginatus most common tooth

Maxillary lateral incisor (also central incisors); maxillary predominance

Dens invaginatus Type I

Confined to the crown

Dens invaginatus Type II

Extends below CEJ and ends in a blind sac

Dens invaginatus Type III

Extends through the root and perforates the apical or lateral radicular area

Radicular dens invaginatus

Rare; due to inappropriate invagination of Hertwig's epithelial root sheath with a strip of enamel along the root surface

Taurodontism

Enlargement of body/pulp chamber of a multirooted tooth with apical displacement of pulpal floor and root bifurcation ("bull teeth")

Hypotaurodontism

Mild degree of taurodontism

Mesotaurodontism

Moderate degree of taurodontism

Hypertaurodontism

Severe degree of taurodontism

Taurodontism field effect

First molar least affected, increasing severity toward second and third molars

Hypercementosis

Non-neoplastic deposition of excessive cementum continuous with normal radicular cementum

Hypercementosis common tooth

Premolars; incidence increases with age

Hypercementosis X-ray finding

Thickening/blunting of root; PDL space is maintained around area of proliferation

Dilaceration

Abnormal angulation or bend in the root (or less often the crown) of a tooth

Dilaceration etiology

Trauma to tooth germ causing displacement/formation at abnormal angle; can also be secondary to cyst, odontoma, or supernumerary tooth

Dilaceration most affected teeth

Permanent maxillary and mandibular incisors