LOCAL CAUSES OF MALOCCLUSION Flashcards
what are the main aetiological causes of malocclusion?
- skeletal = class 2/3, high FMPA
- dental = missing teeth
- soft tissue = lip trap
- other = habits
what is the definition of a local cause of malocclusion?
a localised problem or abnormality within either arch, usually confined to one, two or several teeth producing a malocclusion
what are some examples of local causes of malocclusion?
- variation in tooth number
- variation in tooth size or form
- abnormalities of tooth position
- local abnormalities of soft tissues
- local pathology
what are examples of conditions that cause a variation in tooth number? (resulting in malocclusion)
- supernumerary teeth (extra)
- hypodontia (developmentally absent teeth)
what examples of variation of timing can cause malocclusion?
- retained primary teeth
- early loss of primary teeth
- unscheduled loss of permanent teeth
what are supernumerary teeth?
a tooth or tooth-like entity which is addition to the normal series of teeth
who is more likely to get supernumerary teeth? where is this more common & what is the prevalence?
- males > females
- most common in anterior maxilla
- 1% in primary dentition
- 2% in permanent dentition
what are the four types of supernumerary teeth?
- conical
- tuberculate
- supplemental
- odontome
what are the features of conical supernumerary teeth?
- small & peg shaped
- found close to midline
- usually 1 or 2 in number
- tend to erupt though gingiva
- may displace adjacent teeth but tend not to prevent eruption of normal teeth
what are the features of tuberculate supernumerary teeth?
- tend not to erupt
- usually paired
- barrel-shaped
- one of the MAIN CAUSES of failure of eruption of permanent upper incisors
what are the features of supplemental supernumerary teeth?
- extra teeth of NORMAL MORPHOLOGY
- usually upper lateral or lower incisors
- often extract these
what are compound odontome supernumerary teeth?
- discreet denticles
what are complex odontome supernumerary teeth?
disorganised mass of dentine, pulp and enamel
what is hypodontia?
developmental absence of one or more teeth
who is more likely to suffer from hypodontia?
females > males (3:2)
what teeth are often missing in a patient with hypodontia?
upper laterals or second premolars
why are primary teeth sometimes retained in the mouth?
- absent successor
- ectopic successor or dilacerated
- infra-occluded (ANKYLOSED) primary molars
- dentally delayed in terms of development
- pathology/supernumerary
if a patient has an absent successor permanent tooth, what are the options?
- maintain primary tooth as long as possible
- extract deciduous tooth early to encourage space closure
what is infra-occlusion of primary molars?
process where a tooth fails to achieve or maintain its occlusal relationship with adjacent teeth
- temporal ankylosis
- percussion sound
what is the definition of “slight” infra-occlusion of a primary molar?
between occlusal surface and interproximal contact, less than 2mm
what is the definition of “moderate” infra-occlusion of a primary molar?
within occluso-gingival margins of interproximal contact
what is the definition of “severe” infra-occlusion of a primary molar?
below interproximal contact point
why might early loss of primary teeth occur?
- trauma
- periapical pathology
- caries
- resorption by successor
If a primary tooth is lost, what does subsequent crowding of permanent teeth depend on?
- which tooth is extracted
- when the tooth is extracted
- the patients inherent crowding
what occurs if primary incisors are lost early?
- very little impact
- no compensating or balancing extraction
what occurs if primary canines are lost early?
- unilateral loss in crowded arch can give centre-line shift
- will get some mesial drift of buccal segments
- consider balancing extraction
what occurs if primary molars are lost early?
- more space loss with Es >Ds
- more space loss in upper > lower
- 6s drift mesially and steal 5 space
what factors influence the impact of the loss of 6s?
- age at loss
- crowding
- malocclusion
what is the condition when teeth are too large?
macrodontia
what is the name of the condition when teeth are too small?
microdontia
what problems are caused by macrodontia?
- crowding
- asymmetry
- aesthetics
what problems can arise from microdontia?
- leads to spacing
- linked to hypodontia
what are examples of abnormal form conditions of teeth?
- peg shaped laterals
- dens in dentate
- germinated/fused teeth
- talon cusps
- dilaceration
- accessory cusps & ridges
at what ages do you check for palpable buccal canine bulge?
from 9 years onwards
what are ectopic first molars a sign of?
- crowding (greater in CLP)
- mesial path of eruption
- abnormal morphology of E
what are the features of ectopic first molars?
- less than 5%
- more commonly U arch
- reversible before age 8
what is the dental definition of transpositions?
interchange in the position of two teeth
what are the 2 classifications of transpositions in teeth?
- true
- pseudo
what teeth are most commonly transpositioned?
- upper canines & first molars
- lower canines and incisors
what local abnormalities of soft tissues can cause malocclision?
- digit sucking
- fraenum
- tongue thrust
what are the clinical features of a digit sucking habit?
- proclined upper incisors
- retroclined lower incisors
- anterior open bite
- unilateral posterior crossbite
what can abnormality of the labial fraenum lead to in relation to malocclision?
may cause median diastema
