Disorders of Tooth Formation Flashcards
What are the clinical terms for missing teeth?
What treatment is appropriate for missing teeth?
- hypodontia: failure of development, 8’s most common, followed by 5’s, then upper 2’s
- anodontia: total lack of teeth
- 0.1%-0.9% primary dentition prevalence, 3.5-6.5% in permanent dentition
- missing permanent teeth are seen in 30-50% of patients who have missing primary teeth
- unknown aetiology but related to multiple births, low birth weight, syndromes (downs, x-linked), disorders involving ectodermally derived structures (nails, teeth, hair, sweat glands)
Treatment: - full and partial dentures
- implants
- missing and small teeth are often present together, composite advised to mask conical or mis-shaped teeth
What is hyperdontia?
Extra teeth = supernumerary
- 0.2%-0.8% in primary dentition, 1.5-3% permanent
- male to female ratio 2:1
- patients with supernumerary primary teeth have 30-50% chance of being followed by supernumerary permanent teeth
- could prevent eruption of permanent teeth - take radiographs in delayed eruption to figure out if supernumerary is causing issues
Location: - anterior maxilla in the midline or immediately adjacent to midline referred to as mesiodens
- molar regions referred to as paramolars or distomolars
- 5x more likely in maxilla than mandible
- usually idiopathic but may be associated with syndromes such as cleidocranial dysplasia
What is the term given to teeth larger than normal?
Teeth smaller than normal?
Macrodontia/megadontia: rare, seen in cases of pituitary gigantism where all teeth are larger than normal, more common in males
Microdontia: teeth smaller than normal, max lateral incisors and third molars commonly affected, max lateral incisors (peg/conical shaped crowns)
- identified radiographically, more common in females, associated with ectodermal dysplasia and downs syndrome
What can affect root size?
Which healthcare professionals are involved in treatment planning of abnormality in tooth morphology?
- racial variation: shorter roots see in in people of oriental background and larger roots in patients with african origin
- irradiation of the jaws or chemotherapy during root formation may lead to smaller roots
- possibly orthodontic treatment
- dentine and pulp dysplasia may affect root size e.g. dentinogenesis imperfecta
Paediatricians, orthodontists and restorative dentists are all active in treatment planning
What are the two types of double teeth?
Gemination: attempts at developmental separation of a single tooth germ to produce two separate teeth, 1 canal and incisal notching, anteriors and deciduous teeth most commonly affected, cause unknown/rare
Fusion: union of two normally separated adjacent tooth germs, more common in primary dentition, 2 canals, cause unknown, may be 1 normal tooth fusing with a supernumerary
What is concrescence?
Concrescence: joining of two teeth, one of which may be a supernumerary, by cementum (root surface)
- cause thought to be trauma or overcrowding, root surfaces in close proximity
- maxillary molars most commonly affected
What is dilaceration?
- gross disruption of root formation
- cause is thought to be trauma to tooth germ during root development
- remainder of tooth forms at an angle
- may appear anywhere along root surface
- usually discovered radiographically
- can impede tooth eruption
What are some treatment options for double teeth, concrescence and dilaceration?
Primary dentition: no treatment
Permanent dentition dependant on:
- space available within arch
- morphology of pulp chambers and root canals
- degree of attachment between the two parts of the tooth or teeth
What is an invaginated tooth?
Infolding on the palatal surface of the crown of the tooth and lined with enamel, sometimes extending into the root. Dens in dente, gestant/dilated composite odontomes, dens invaginatus
- normal tooth tissue in abnormal form
- appear as normal shape or malformed crown that exhibits a deep pit or crevice in area of cingulum
- detected radiographically as a tooth-like structure appearing within a tooth
- pear-shaped enamel mass seen in dentine surrounding a radiolucent area
- tooth within a tooth
Treatment:
- fissure seal soon after eruption - cingulum likely to get caries
- vitality test/radiograph
- endodontic treatment if pulp involvement
What is evaginated teeth?
- small tubercle on occlusal surface of premolar in the central part of the fissure pattern
- more common in chinese patients
- typically worn down/fractured off with normal wear
Treatment: - raadiographic evaluation to determine any pulpal involvement (pulp horns present in evagination) - restricted and repeated grinding of the tubercle followed by a fissure sealant
- removal of tubercle and limited pulpotomy may be required
What is dens evaginatus?
- talon cusp: horn like projection of the cingulum of the maxillary incisor teeth which may reach and contact the incisal edge of the tooth
Treatment: - fissure seal margins - possible pulpotomy
- no treatment if no interference with occlusion
What is taurodontism?
Bull like teeth: molar teeth where the pulp chambers of the teeth are enlarged vertically at the expense of the roots
Genetic/syndromes i.e. ectodermal dysplasia
What is amelogenesis imperfecta?
- applied to generalised enamel defects affecting all or predominantly all of the teeth of both the primary and permanent dentitions
- may be genetic/inherited
- the incomplete or defective formation of enamel, resulting in the alteration of tooth form or colour
Enamel hypoplasia results from a disturbance of or damage to the ameloblasts during enamel matrix formation - ameloblasts are one of the most sensitive cell groups in the body
- thinner enamel
- grooved or pitted
- glossy
- hard and translucent
- severe cases of measles or vitamin D deficiency
What is hypomineralisation?
Defect in mineralisation of enamel
- no translucency
- normal thickness but very soft
- discoloured yellow/brown
- opaque and chalky
- prone to caries, enamel very weak
- enamel chips easily
- poorly formed
Management:
- localised defects simple restorative measures e.g. preformed crowns on 6’s ASAP
- sensitive handling of patients
- aesthetics
- sensitive to thermal and mechanical stimuli
- poor OH and staining - likely to have poor motivation
What is dentinogenesis imperfecta?
An inherited disorder of dentine, which may or may not be associated with osteogenesis imperfecta (collagen disorder)
- primary and permanent teeth affected
- teeth are opalescent with a greyish or brown colour
- enamel unaffected structurally, although usually flakes off due to poor adhesion to dentine
- pulpal exposure likely in deciduous dentition
- primary molars have short roots and pulp canal obliteration
- permanent dentition generally less severely affected
Management: as for amelogenesis imperfecta
