Dental Anomalies 1 Flashcards
What are the stages of tooth development?
Initiation
Bud stage
Cap stage
Bell stage
Dentinogenesis
Amelogenesis
Continued dentinogenesis/amelogenesis
Eruption
Mature
What happens during the bud stage?
Initiation with migration of neural crest cells into the arches
What happens during the cap stage?
Proliferation.
Condensation of ectoderm and formation of dental organ and dental papilla
What happens during the bell stage?
Morphodifferentiation: Proliferation of inner enamel epithelium to form the shape of the crown.
Histodifferentiation: Differentiation of precursor cells, ameloblasts, and odontoblasts.
What happens during crown formation?
Apposition: Reciprocal induction and laying down of mantle dentine and first enamel.
Calcification
Maturation: Enamel crystal formation
Eruption: Emergence of tooth and continued development of roots
What stage of maturation are the following anomalies associated with?
Supernumerary/hypodontia
Macrodontia/microdontia
Odontogenic cysts
Regional odontoplasia
Enamel hypomineralisation
Amelogenesis imperfecta
Enamel hypoplasia
Dentinogenesis imperfecta
Impacted teeth
Supernumerary/hypodontia: Bud stage (initiation)
Macrodontia/microdontia: Bell stage (morphodifferentiation)
Odontogenic cysts: Cap stage (Proliferation)
Regional odontoplasia: Bell stage (histodifferentiation)
Enamel hypomineralisation: Crown stage (maturation)
Amelogensis imperfecta: Crown stage (calcification)
Enamel hypoplasia: Crown (apposition stage)
Dentinogenesis imperfecta: Crown stage (calcification)
Impacted teeth: Crown stage (Eruption)
What is the difference between an anomaly and a trait?
An anomaly is a rare variant that occurs in any given population. (eg hyperdontia,
A trait is a variant exhibited by a significant number of people in a population such that it is considered a trait for the dentition of that population
What theories are out there about the possible causes of hyperdontia?
Causes remain unclear.
Various theories postulated:
Result of hyperactivity of dental lamina
Tooth germ dichotomy (split tooth germ): An imbalance between molecules = 2 part split of teeth.
Genetic predisposition
Environmental factors
Multifactorial, combination of environmental and genetic factors
How common is hyperdontia?
Prevalence is higher in permanent dentition (0.5 - 3.5%) than primary dentition (0.2 -0.8%)
Who more commonly gets hyperdontia?
Males > Females
Which areas are most commonly affected by hyperdontia?
Maxillary incisor region > mandibular premolars > maxillary molar region
What are the types of classifications of supernumerary teeth?
Location (mesiodens, paramolar, distomolar, parapremolar)
Morphology (conical tuberculate, supplemental (or eumorphic), odontome (can be simple or complex)
Orientation (Vertical or normal, inverted, or horizontal)
Position (Buccal, palatal or transverse)
What is the most common type of supernumerary tooth?
Mesiodens (“Most mesially invested tooth” “the lost incisor”)
Which conditions are associated with hyperdontia? (most important causes are mentioned first)
Cleidocranial dysplasia
Gardner syndrome (Familial adenomatous polyposis)
Cleft lip and palate
Nance-Horan syndrome
Tricho-Rhino-Phalangeal syndromes
Fabry Anderson’s syndrome
Ehlers-Danlos syndrome
Incontinentia pigmenti
What are odontomes?
A benign tumour linked to tooth development. Specifically, it is a dental hamartoma, meaning that it is composed of normal dental tissue that has grown in an irregular way.
How are odontomes treated?
Surgical enucleation
May require surgical exposure and orthodontic alignment
What are the clinical signs of hyperdontia?
Spacing eg midline diastema
Failure of adjacent teeth to erupt (Especially with failure of upper incisors to erupt, also may cause retention of primary incisors)
Displacement (May cause displacement of permanent tooth from mild rotation to complete displacement)
Eruption into the mouth
Local crowding or irregularity
What are the potential complications of hyperdontia?
Failure of eruption of permanent teeth
Displacement or rotation or crowding
Ectopic eruption of permanent teeth
Abnormal diastema or premature space closure
Dilaceration, delayed or abnormal root development of permanent teeth
Pathology (dentigerous cyst formation)
Rare complication (root resorption/loss of viability or nasal eruption)
How can hyperdontia be diagnosed?
Clinical examination (failed or eruption disturbance of permanent tooth)
Routine radiographic finding
As part of a syndrome (Cleidocranial dysplasia)
How can hyperdontia be treated?
Long term monitoring
Extraction
Surgical removal
What is hypodontia?
Developmental absence of one or more teeth excluding third molars
What is the difference between hypodontia, oligodontia, and anodontia?
Anodontia = no teeth
Oligodontia = 6 more more missing teeth
Hypodontia = < 6 missing teeth
What does hypodontia tell us about the rest of the body?
Agenesis of teeth is associated with syndromes or systemic abnormalities.
What are the classifications of hypodontia?
Mild = 1 - 2 missing teeth
Moderate = 3 - 5 missing teeth
Severe = > 6 missing teeth
How common is hypodontia?
Uncommon in primary (0.1 - 4.1%)
More common in permanent (4 - 6% caucasian)
Where is hypodontia most common? (3 most common sites)
- 9% of cases are in mandibular second premolars.
- 3% in maxillary lateral incisors
- 7% in maxillary second premolars
Which jaw is more commonly affected by hypodontita?
the maxilla (53.2%)
What is hypodontia often associated with?
Several theories (both genetic and environmental)
Hypodontia is often associated with small teeth.
It can be isolated in non-syndromic or complex methods.
What genes are involved in the majority of cases of hypodontia?
MSX1
PAX9
AXIN2
What environmental factors can result in hypodontia?
Intra-uterine effects of drugs (eg thalidomide)
Early radiotherapy + chemotherapy
Trauma (alveolar or jaw fracture, jaw surgery, iatrogenic damage to permanent tooth germ from traumatic extraction)
Infections (eg rubella)
What are the major syndromes associated with hypodontia that should be noted? (most important 2 first)
Hypohidrotic ectodermal dyplasia (HED)
Axenfeld-Rieger syndrome (Rieger Syndrome)
Dento-alveolar clefting
Trisomy 21
Oral-facial digital syndrome type 1
Williams (Beuren syndrome) (WBS)
Solitary Median Maxillary Central Incisor
Oligodontia and Colorectal Cancer Syndrome
What are the clinical features of hypodontia?
Delayed/asymmetric eruption of permanent teeth
Retained or infraoccluded deciduous teeth
Absent deciduous teeth
Can be associated with short root anomaly.
What are the common orthodontic changes to teeth that occur in patients with hypodontia?
Lip protrusion
Increased overbite
Increased rotations of teeth
Increased prevalence of ectopic maxillary canines
Reduced mandibular plane angle
How are teeth treated in hypodontia?
Acid-etch retained composite buildups of conical teeth
Orthodontic management of spaces
Removable prosthesis (partial dentures, conventional dentures, overdentures)
Fixed prosthesis (Composite resin veneers, crowns, and bridges)
Autotransplantation
Osseointegrated implants (usually after cessation of growth)
How does microdontia commonly manifest?
In general microdontia teeth are small, the crowns are short, and normal contact areas between the teeth are frequently missing.
In which people is microdontia most prevalent?
Permanent dentition > primary dentition
Females > Males
Maxillary teeth > Mandibular teeth
Permanent dentition (1.9 - 6.9%) > primary dentition (0.5 - 6.3%) Most prevalence data are available for maxillary lateral incisors.
What are the classifications of microdontia?
True generalised microdontia
Generalised relative microdontia
Localised microdontia
What is true generalised microdontia?
All teeth smaller than normal
All of the teeth are of a normal morphological form
This is very rare. Reported in Radiation/chemotherapeutic treatment during development stage of the teeth
Pituitary dwarfism
Fanconi’s anaemia
What is generalised relative microdontia?
Normal or slightly smaller than normal teeth but the jaws are somewhat larger than normal (impression of microdontia)
Inheritance of jaw size from one parent and tooth size from other parent can lead to this.
Which tooth is most commonly affected by localised microdontia?
Maxillary lateral incisor
What are the subtypes of localised microdontia?
Microdontia of the whole tooth
Microdontia of the crown of the tooth
Microdontia of the root alone
What is the name given to maxillary lateral incisors affected by microdontia? What are the features of these maxillary lateral incisors?
PEG lateral incisors.
the roots are frequently shorter than normal
Which conditions and syndromes are commonly associated with microdontia?
patients with ectodermal dysplasia often present with microdontia.
Pituitary dwarfism
Down syndrome
Facial hemiatrophy
William’s syndrome
Chromosome d/u, 45X
How is microdontia treated?
Composite resin buildup
Porcelain veneers
Ceramic crown
Cast restoration
Orthodontic alignment and extraction of the tooth
Autotransplantation
Extraction and implants
What is the definition of macrodontia?
Tooth size that is outside normal limites of variation for that type. For practical purposes, a tooth that is 1mm larger than their antimere or the mean dimension of the tooth, and exhibits normal crown, root and pulp morphology.
Where is macrodontia most commonly seen?
Male > Female
Permanent dentition (1.1 - 3.6%) > Primary dentition (0 - 2.3%
What are the classifications of microdontia?
True generalised macrodontia
Generalised relative microdontia
Localised macrodontia
How is macrodontia treated?
Stripping of the macrodont with or without resin build-up of antimere.
Extraction and replacement by fixed prosthesis, removable prosthesis, or implant.
Autotransplantation.
What are potential complications caused by macrodontia?
Problems with aesthetics
Arch length discrepancies
Crowding
Disruption of the developing occlusion
Teeth predispose to caries.
What conditions are associated with macrodontia?
Pituitary gigantism
Hemifacial hyperplasia
Otodental syndrome
Klinefelter syndrome
KBG syndrome
Pineal hyperplasia with hyperinsullinism
What are the features of generalized relative macrodontia?
It is more common than true macrodontia
Normal or slightly larger sized teeth in smaller jaws
An illusion of generalized macrodontia
Hereditary factors
In which teeth is macrodontia most commonly reported?
Incisors and canines.
however alos common in second mandibular premolars, mandibular molars or premolars, and third molars
