Aetiology of malocclusion 2 Flashcards
What is the etiology of malocclusion split into
skeletal
dental
soft tissue
other
What are examples of skeletal issues that cause malocclusion
class III high FMPA
What are examples of dental issues that cause malocclusions
missing teeth
What are examples if soft tissue issues that cause malocclusions
lip trap
What is the definition of local causes of malocclusion
localized problem or abnormality within either arch, usually confined to one, two or several teeth producing a malocclusion
What 5 areas can local causes of malocclusion be divided into
variation in tooth NUMBER variation in tooth size or FORM abnormalities of tooth POSITION local abnormalities of SOFT TISSUES local PATHOLOGY
What are variations in tooth number
supernumerary teeth
hypodontia
What is a supernumerary tooth
tooth or tooth like entity which is additional to normal series
Where are supernumerary teeth most common
anterior maxilla
Which gender are supernumerary teeth most common
males
What is the prevalence of supernumerary teeth
1% in primary dentition
2% in permanent
What are the four types of supernumerary teeth
conical
tuberculate
supplemental
odontome
What is the shape of conical supernumerary teeth
small peg shaped
may erupt so extract
usually 1 or 2
tend not to prevent eruption but may displace adjacent teeth
What are mesiodens conical supernumerary
mesiodens
What are the tuberculate supernumerary
tend not to erupt
paired
barrel shaped
usually extracted
What are the tuberculate supernumerary teeth
failure of eruption of permanent upper incisors
What are supplemental supernumerary teeth
extra teeth of normal morphology
most often upper laterals or lower incisors
can eat raid premolars or fourth molars
often extract - decision based on form and position
What are odontome supernumerary teeth
command - discreet denticles
complex - disorganized mass of dentine, pulp and enamel
What is hypotonia
developmental absence of one or more teeth
Which gender is hypodontia more prevalent with
females
What teeth are most commonly effected by hypodontia
upper lateral 2s
second premolars
What are retained primary teeth
a disruption in the sequence of eruption
When should alarm bells ring about retained primary teeth
difference of more than 6 months between the shedding of contra lateral teeth (alarm bells)
Why may primary teeth be retained
absent successor
ectopic successor or dilacerated
infra occluded (ankylosed) primary molars
dentally delayed in terms of development
pathology/supernumary
What should you do if there is a retained primary tooth with an absent successor
either maintain primary tooth for as long as possible if it has a good prognosis
or
extract deciduous tooth early to encourage spontaneous space closure in crowded cases
early ortho referral for advice is best
What are infra occluded primary molars
(was called submerging before)
process where a tooth fails to achieve or maintain its occlusal relationship with adjacent teeth
temporary ankylosis
common in 1-9%
What type of sound do the infra occluded primary molars make
percussion sound
What is the management of a retained infra occluded primary molar if there is a permanent successor present
usually self corrects so keep under review
consider extraction if
1. contact points are going subgingival
2. root formation of successor is near completion
What is the management of a retained infra occluded primary molar if there is not a permanent successor present
depends on potential crowding
retain if in good condition
extract and plan space management
What is early loss of primary teeth due to
trauma
periapical pathology
caries
resorption by successor
What can early loss of primary teeth result in
crowding
centre line shift
What does the result of early loss of primary teeth depend on
which tooth is extracted
when the tooth is extracted
patients inherent crowding
What is a balancing extraction
extraction of a tooth from the opposite side of the same arch
designed to minimize midline shift
What is a compensating extraction
by extraction of a tooth from the opposing arch of the same side
designed to minimize maintain occlusal relationships
What is the impact of the early loss of primary incisors
very little impact
no compensating or balancing extraction needed
What is the impact of early loss of primary canines
unilateral loss in crowded arch, can give centre-line shift
will et some mesial drift of buccal segments
consider balancing extraction
What is the impact of early loss of primary molars
more space loss with Es and Ds
more space loss in upper > lower
6’s drift medially and steal 5s spaces
tend not to balance or compensate
What is the effect when primary teeth are extracted
most effect is when primary teeth are extracted early
little effect is extracted late
What is the effect when there is inherent crowding
marked space loss in crowded px
minimal or no space loss in spaced dentition
When is the routine assessment for the prognosis of 6’s done
at age 8-9
seldom ideal tooth of choice for relief of crowding
but planned loss at correct age is better than later enforced loss
What are factors that influence the impact on the loss of 6s
age at loss
crowding
malocclusion
Is age an important factor for the age at loss for 6s
no
less important
When is the ideal time for extraction of 6’s
ideally at time of bifurcation development in 7s
If the lower 6 is extracted too late what happens
the 7s have erupted already
often poor space closure
If the lower 6 is extracted too early what can happen
distal drift of 5s
If there is crowding in the upper arch and there is loss of 6s what can happen
rapid space loss
If the lower arch is spaced what is the impact on the loss of 6s
will have spaces
If the lower arch is aligned what is the impact of the loss of 6s
will have spaces
If the lower arch is crowded what is the impact of the loss of 6s
best results likely
If an upper 6 has to go do we compensate
no
If a lower 6 has to go do we compensate
often yes
What should we do about the unschedules loss of central incisor
in first instance maintain space by reimplanting
then plan how to deal with space
What are the 3 variations in tooth size and form
too large - macrodontia
too small - microdontia
abnormal form
What is macrodontia
tooth/teeth larger than average
localized or generalised
What are problems that arise from macrodontia
crowding
asymmetry
aesthetics
What is microdontia
tooth/teeth smaller than average
localized or generalised
leads to spacing
linked to hypodontia
What are different abnormal forms of teeth
peg shaped laterals dens in dente geminated/fused teeth talon cusps dilaceration accessory cusps and ridges
What are abnormalities of tooth position called
ectopic teeth
What teeth are most commonly atopic
third molars upper canines first permanent molars upper centrals transpositions
What percentage of population have ectopic canines
1-3%
What percentage of ectopic canines are palatal
80%
What are ectopic canines associated with
small or absent upper laterals
How do we check for ectopic canines
check for palpable buccal canine bulge from 9 years onward
further investigation or refer if in doubt
What is the clinical assessment for ectopic canines
visualisation/palpation for any obvious bumps of 3
inclination of 2
mobility of c or 2
color of c or 2
How many radiographs are needed for ectopic canines
2 - usually OPT and anterior occlusal
can do vertical parallax too
What are the 3 Ps we look for in radiography of ectopic canines
presence
position
pathology
What are the management options for ectopic canines
prevention
extraction to encourage improvement in position of 3 (interceptive)
retain 3 and observe (accept its position)
surgical exposure and orthodontic aligmnet
surgical extraction
autoimplantation
How can we prevent ectopic canines
appropriate to monitor from 9 onwards
clinical assessment - look for symmetry
How common are ectopic first molars
less than 5%
What arch are ectopic first molars most common in
upper
At what age are ectopic first molars reversible
8
What are signs of ectopic first molars
crowding
mesial path of eruption
What is management of ectopic first molars
seperator
attempt distalize 6
extract e
When looking at ectopic upper central incisors what do we check for
sequence
symmetry
Why can upper central incisors become ectopic
supernumerary
dilacerated (trauma)
What is possible tx for ectopic central incisors
surgical exposure removal of supernumerary if present and bond a gold chain
make space
above 9 years ortho traction
bonded retainers
What is transposition
interchange in the position of two teeth
What can transposition be classified into
true and pseudo
What teeth are most commonly transposition
upper canine and first premolar
lower canine and incisor
What are the tx options for transposition
accept
extract
correct
What are the 3 local abnormalities of soft tissue
digit sucking
frenum
tongue thrust
What is the effect of non nutritional digit sucking habits
proclined UI
retroclined LI
anterior open bite
unilateral posterior cross bite
What can a labial frenum cause
median diastema
What can tongue thrust cause
anterior open bite
What are the local pathologies that can cause malocclusion
caries
cysts
tumours
