Textbook Flashcards
orthodontics
branch of dentistry concerned with facial growth, development of the dentition and occlusion and the diagnosis, interception and treatment of occlusal anomalies
ideal occlusion
term given to dentition where the teeth are in the optimum anatomical position, both within the mandibular and maxillary arches (intramaxillary) and between the arches when the teeth are in occlusion (intermaxillary)
malocclusion
term used to describe dental anomalies and occlusal traits that represent a deviation from the ideal occlusion
In reality, rare to have a truly perfect occlusion and malocclusion is a spectrum – variation around the norm
prevalence of occlusal abnormalities
depends on population studied (e.g age and racial characteristics), criteria used for assessment, methods used by examiners (e.g. if radiographs used)
rationale for orthodontic treatment
Malocclusion may cause concerns related to the dental health and/or oral health related quality of life issues arising from appearance, function and psychosocial impact of teeth
Need for treatment depends on the impact of the malocclusion and whether treatment is likely to provide a demonstrable benefit to the pt
Need for ortho Tx depends on
the impact of the malocclusion and whether treatment is likely to provide a demonstrable benefit to the pt
to judge treatment need
potential benefits of Tx balanced against the risk of possible complications and side effects in a risk-benefit analysis
benefit of ortho Tx (4)
Improved dental health
Improved oral health related quality of life
Improved aesthetics
Improved function
risks of ortho Tx (3)
Worsening of dental health
Failure to achieve aims of Tx
Relapse
why do people need ortho Tx
Health and wellbeing benefits are the most appropriate determinant of Tx need
Orthodontic indices have been developed to help objective and systematic evaluation of the potential risk to dental health posed by malocclusion and the possible benefits of orthodontic treatment
reason for orthodontic indices
been developed to help objective and systematic evaluation of the potential risk to dental health posed by malocclusion and the possible benefits of orthodontic treatment
While indices were mainly developed to measure treatment need, due to high treatment demand in many countries they are also used to manage demand and support prioritisation through some form of rationing
e.g. Uk acceptance for NHS orthodontics is based on need for treatment determined by the Index of Orthodontic Treatment need (IOTN), Sweden treatment priority is estimated using priority index developed by Swedish Orthodontic Board and the Medical Board – most severe first
unmet ortho Tx depends on (3)
Individuals desire for treatment
Organisation factors – availability and access to services,
Cost
UK unmet ortho treatment need for children from deprived houses is 40% 12 yo and 32% 15 yo (higher than average)
Similar inequality patterns for access to Tx seen in other countries
demand and willingness for ortho care
higher in females, and higher SES, smaller population: orthodontist ratio (assumed to be because increase awareness and acceptance of appliances)
Demand for treatment does not reflect the objective treatment need
Some pts very aware of minor deviations- e.g. mild rotation upper incisors – whilst others refuse Tx for severe malocclusions
Demand increasing as rise in less visible appliances (ceramic brackets, lingual fixed appliances, orthodontic aligners). As well as increasing dental awareness and desire for straight teeth – more acceptance also means many adults who didn’t have tx when young now want
ortho role with restorative
adjunctive
- People keeping teeth for longer is contributing for more requests for interdisciplinary care
ortho relation to caries, plaque induced perio and TMD
insufficient evidence that ortho treatment beneficial
- Complex and multifactorial in origin, thus direct casual relationship with malocclusion ins difficult to measure effectively
ortho relation to localised periodontal problems
certain occlusal anomalies can predispose, particularly where the gingival biotype is thin, here orthodontic intervention can have a long term health benefit
e. g.
- Crowding causing tooth/teeth to be pushed out of the bony trough, resulting in recession
- Periodontal damage related to traumatic overbits
- Anterior crossbites with evidence of compromised buccal periodontal supported on affected lower incisors
- Increase overjet with increased risk of dental trauma
- Unerupted impacted teeth with risk of pathology
- Crossbites associated with mandibular displacement
dental trauma and orthodontics
Increased overjet is associated with trauma to upper incisors – 2 systematic reviews found risk of injury is more than double in individuals with an overjet greater than 3mm, risk increases with overjet size and lip incompetence
- Increased risk of dental trauma – indicated ortho Tx
Mouthguards – imp in reducing risk of dental trauma esp in contact sports
tooth impactation
when normal tooth eruption is impeded by another tooth, bone, soft tissues or other pathology
supernumerary teeth
cause impaction and if judge to be impeding normal dental development – orthodontic intervention needed
ectopic teeth
that have been formed, or subsequently moved into, wrong position
- Often become impacted
unerupted impacted teeth
may cause localised pathology – commonly resorption of adj roots or cystic change
Most frequently seen in relation to ectopic maxillary canine teeth – can resorb roots of incisors and premolars
uncontrolled caries and orthodontic appliance placement
Caries reduction is rarely an appropriate justification for orthodontic treatment and placement orthodontic appliances with uncontrolled caries risk factors is likely to cause significant harm
when may orthodontic Tx help resolve caries
Malignment in caries suspectable children (e.g. special needs) may reduce capacity for natural tooth cleansing capacity and increase caries risk
Orthodontic solution sought to reduce food stagnation
- Extraction or alignment to alleviate localised crowding
plaque control
if poor contraindication for orthodontic Tx
before ortho Tx it is essential
OH is satisfactory and any periodontal condition is controlled prior to considering orthodontic treatment
what may hinder effective brushing
Reduced dexterity or restricted cleaning access may find irregular teeth a hinderance in effective brushing
TMD
compromises a group of related disorders with multifactorial aetiology including psychological, hormonal, genetic, traumatic and occlusal factors
- Depression, stress and sleep disorders are major factors in aetiology of TMD
- Parafunctional activity (bruxism) can contribute to muscle pain and spasm
Due to multifactorial aetiology ortho is neither “cause” or “cure” of TMD
how to manage TMD
Conservative and reversible approaches are advised to help manage TMD
oral health related quality of life (OHRQoL) 4 components
appearance
masticatory function
speech
psychological well being
appearance components of OHRQoL
Often principle reason
Psychological benefit of improved appearance
masticatory function components of OHQoL
Significant interarch discrepancy including anterior open bits (AOB) and markedly increased or reverse overjet often report difficulty with eating particularly incising food
- Avoidance certain foods (apples, sandwiches), embarrassment eating in public
Severe hypodontia – hard as fewer teeth to bite on and concerns about dislodging mobile teeth and prosthetic teeth
speech components of OHRQoL
Complex Neuromuscular process
- Respiration, phonation, articularion and resonance
Orthodontic Tx unlikely to significantly change speech (formed early life prior to permanent dentition)
Lisp – if cannot get contact between incisors (interdental sigmatism) – need to correct incisor relationship and interdental spacing – improve confidence
articulation
formation of different sounds through variable contact of the tongue with surrounding structures inc palate , lips, alveolar ridge and dentition
lisp due to and Tx
if cannot get contact between incisors (interdental sigmatism)
need to correct incisor relationship and interdental spacing – improve confidence
psychological wellbeing OHRQoL
Malocclusion – reduced self conficence and self esteem, possible mediator
Attractive dental appearance – friendlier, more interesting and intelligent, more successful and more socially competent
Deviation from norm can cause stigmatisation and high correlation between victimisation, malocclusion and quality of life
6 intra oral risks of orthodontic Tx
root resorption
loss of periodontal support
demineralisation
enamel damage
soft tissue damage
loss of vitality
Avoidance/management of
root resorption due to ortho
avoid treatment in patients with resorbed, blunted or pipette shaped roots. In teeth judged to be at risk, monitor roots radiographically and terminate Tx if root resorption evident
recognised risk factors for root resorption during ortho Tx
- Shortened roots with evidence of previous root resorption
- Pippette shaped or blunted roots
- Teeth which have suffered previous episode of trauma
- Patient habits (e.g. nail biting)
- Iatrogenic – use excessive forces, intrusion, prolonged treatment time
Avoidance/management of
loss of periodontal support due to ortho
maintain high level of oral hygiene
avoid moving teeth out of alveolar bone
Avoidance/management of
demineralisation due to ortho
diet control, high level of oral hygiene, regular F exposure
abandon Tx
Avoidance/management of
enamel damage due to ortho
avoid potentially abrasive components e.g. ceramic brackets where there is a risk of occlusal contact
use of appropriate instruments and burs to remove appliances and adhesives
Avoidance/management of
soft tissue damage due to ortho
avoid traumatic components
orthodontic wax or silicone to protect against ulceration
manage allergic reaction promptly
Avoidance/management of
loss of vitality due to ortho
if history of previous trauma to incisors counsel pt
2 extra oral problems due to ortho
worsening facial profile
soft tissue damage
Avoidance/management of
worsening facial profile due to ortho
careful treatment planning and appropriate mechanics
Avoidance/management of
soft tissue extra oral damage due to ortho
use of appropriate safety measures with headgear
manage allergy promptly
ineffective ortho treatment risks
relapse
failure to achieve treatment objectives
Avoidance/management of
ortho relapse
avoidance of unstable tooth positions at end of treatment
long term retention
Avoidance/management of
failure to achieve ortho Tx objectives
thorough assessment and accurate diagnosis
effective treatment planning
appropriate use of appliances and mechanics
reasons for failure to achieve ortho treatment objectives are:
Operator factors:
Patient factors: poor oral hygiene/diet, failure to wear appliances/elastics, repeated appliance breakages, failure to attend appointments, unexpected unfavourable growth
operator factors for failure to achieve ortho treatment objectives (6)
error on diagnosis,
errors of treatment planning,
anchorage loss,
technique errors,
poor communication,
inadequate experience/training
patient factors for failure to achieve ortho treatment objectives (5)
poor oral hygiene/diet,
failure to wear appliances/elastics,
repeated appliance breakages,
failure to attend appointments,
unexpected unfavourable growth
3 key points when discussing orthodontic treatment needs
The decision whether to embark on orthodontic treatment is essentially a risk-benefit analysis
The perceived benefits of orthodontics intervention should outweigh any potential risks associated with treatment
Patients and families have an important role in determining whether treatment is likely to address issues caused by malocclusion
which occlusion state is more important - functional or static
FUNCTIONAL
- Occlusion which is free on interferences of smooth gliding movements of mandible with no pathology
Orthodontic treatment should aim to achieve a functional occlusion
aim for ortho Tx
FUNCTIONAL OCCLUSION
Occlusion which is free on interferences of smooth gliding movements of mandible with no pathology
malocclusion is
not disease – variation around ideal
classes of factors for aetiology of malocclusion
genetic or
environmental or
both
3 things to consider their role in aetiology when planning ortho Tx
- Skeletal pattern – in all 3 places of space
- Soft tissue
- Dental factors
why do we categorise ortho issues
salient features is helpful for describing and documenting a pts occlusion
- Classification and indices allow prevalence in population to be determined
qualitative assessment of malocclusion is
Descriptive – diagnostic classification of malocclusion
Occlusion is a continuous variable so that the clear cut off points between different categories does not always exist
- Issue in classifying borderline malocclusion
Helpful shorthand method of describing features
No help in indicating difficulty of Tx
E.g. British Standards Institutes classification of incisor relationship (1983)
quatative assessment of malocclusion
has 2 approaches
Each feature of malocclusion is given a score and the summed total is then recorded (e.g. Peer Assessment Rating (PAR) index)
The worst feature of malocclusion is recorded (e.g. the index of orthodontic treatment need (IOTN))
4 important attributes of an index
Validity – can the index measure what it is designed to measure
Reproducibility – does the index give the same result when recorded on 2 different occasions and by different examiners
Acceptability – is the index acceptable to both professional and pts
Ease of use – in the index easy to use
angle’s classification
Based upon first permanent molar erupted in a constant position within the facial skeleton – used to assess the anterior posterior relationship of arches
- Incorrect assumption
Issue as well with forward dift or loss of FPM – thus superseded
But Still used to describe molar relationship
3 groupings
3 groupings in angle’s classifcation
class I or neutrocclusion
class II or distoocclusion
class III or mesiocclusion
angle’s
class I
neutrocclusion
The mesiobuccal cusp of the upper first molar occludes with the mesiobuccal groove of the lower first molar
angle’s
class II
distooccclsuion
The mesiobuccal cusp of the lower first molar occludes distal to the Class I position
Postnormal relationship
angle’s
class III
mesioocclsuion
The mesiobuccal cusp of the lower first molar occludes mesial to the Class I position
Prenormal relationship
british standard institute classification
Based on incisor relationship
Most widley used descriptive classification
Similar terms to Angles – but not to do with molar relationship –
british standard institute classification
groupings
class I
class II
- division 1
- division 2
class III
british standard institute classification
class I
the lower incisor edges occlude with or lie immediately below the cingulum plateau of the upper central incisors
british standard institute classification
class II division 1
the lower incisor edges lie posterior to the cingulum plateau of the upper incisors
- the upper central incisors are proclined or of average inclination and there is an increase in overjet
british standard institute classification
class II division 2
the lower incisor edges lie posterior to the cingulum plateau of the upper incisors
- the upper central incisors are retroclined. The over jet is minimal usually or may be increased
british standard institute classification
class III
the lower incisor edges lie anterior to the cingulum plateau of the upper incisors. The overjet is reduced or reversed
IOTN
index of orthodontic treatment need
IOTN Shows
Likely impact of malocclusion on individuals dental health and psychosocial well being
2 elements
2 elements of IOTN
dental health component
aesthetic component
dental health component of IOTN
Occlusal traits that could effect the function and longevity of dentition
Single worst feature of malocclusion is noted (index not cumulative) and categorised into one of the 5 grades reflecting need for treatment
- Grade 1 – no need
- Grade 2 – little need
- Grade 3 – moderate need
- Grade 4 – great need
- Grade 5 – very great need
Rule developed to help assessment of dental health component
Since only single worst feature noted an alternative approach is to look consecutively for the following features (MOCDO)
- Missing teeth
- Overjet
- Crossbite
- Displacement (contact points)
- Overbite
dental health component of IOTN grades
- Grade 1 – no need
- Grade 2 – little need
- Grade 3 – moderate need
- Grade 4 – great need
- Grade 5 – very great need
dental health component of IOTN measures
Since only single worst feature noted an alternative approach is to look consecutively for the following features (MOCDO)
- Missing teeth
- Overjet
- Crossbite
- Displacement (contact points)
- Overbite
NOT CUMULATIVE
aesthetic component of IOTN
Thus the likely psychosocial impact upon pt
Set of 10 standard photographs, graded from score 1 (most aesthetically pleasing) to score 10 (least aesthetically pleasing)
- Colour for assessing pt in clinical setting
- Black and white for study models
Teeth in occlusion viewed from anterior aspect and appropriate score determined by choosing the photograph that is thought to pose equivalent aesthetic handicap
Scores categorised in need for treatment:
- Score 1 or 2 – none
- Score 3 or 4 – slight
- Score 5, 6, or 7 – moderate/borderline
- Score 8, 9 or 10 – definite
aesthetic component of IOTN scores
- Score 1 or 2 – none
- Score 3 or 4 – slight
- Score 5, 6, or 7 – moderate/borderline
- Score 8, 9 or 10 – definite
how is aesthetic component of IOTN measured
Set of 10 standard photographs, graded from score 1 (most aesthetically pleasing) to score 10 (least aesthetically pleasing)
- Colour for assessing pt in clinical setting
- Black and white for study models
Teeth in occlusion viewed from anterior aspect and appropriate score determined by choosing the photograph that is thought to pose equivalent aesthetic handicap
IOTN score calculates
as average of dental health component and aesthetic component
IOTN
grade 5
very great
IOTN
grade 4
great
IOTN
grade 3
moderate
IOTN
grade 2
little
IOTN
grade 1
none
what component of IOTN is more widely used alone
Dental health component alone is more widely used
Aesthetic component is criticised for being subjective – esp Class III malocclusion or anterior open bites as photos are of Class I and II cases
peer assessment rating PAR
Success of treatment
Before and end of treatment measures using study models
Scores cumulative (unlike IOTN), weighting is accorded to each component to reflect current opinion in UK as to their relative importance
- Crowding – by contact point displacement (x1)
- Buccal segment relationship – in the anterioposterior, vertical and transverse planes (x1)
- Overjet (x6)
- Overbite (x6)
- Centrelines (x4)
how is PAR calculated
Scores cumulative (unlike IOTN), weighting is accorded to each component to reflect current opinion in UK as to their relative importance
Difference between PAR scores at start and completion of treatment calculated
% change in PAR score reflects success of treatment
- High standard of treatment indicated with mean reduction of greater than 70%
- No appreciable improvement when 30% or less mean reduction
Size of PAR score at beginning gives indication of severity of malocclusion
Obviously hard to achieve a significant reduction in PAR score when there is a low pre-treatment score
ICON
index of complexity, outcome and need
ICON
incorporates features of IOTN and PAR
Following scored and multiplied by their weighting:
- Aesthetic component of IOTN (x7)
- Upper arch crowding/spacing (x5)
- Crossbite (x5)
- Overbite/open bite (x4)
- Buccal segment relationship (x3)
Total sum gives a pre treatment score – reflects the need for and likely complexity of the treatment needed
- More than 43 is said to indicate a treatment needed
Index scored again after treatment to give an improvement grade (outcome of treatment)
Improvement grade = pre-treatment score – (4x post-treatment score)
Criticised for large weighting given to aesthetic component – not widely accepted
ICON improvement grade =
= pre-treatment score – (4x post-treatment score)
ICON scores
Following scored and multiplied by their weighting:
- Aesthetic component of IOTN (x7)
- Upper arch crowding/spacing (x5)
- Crossbite (x5)
- Overbite/open bite (x4)
- Buccal segment relationship (x3)
Total sum gives a pre treatment score – reflects the need for and likely complexity of the treatment needed
- More than 43 is said to indicate a treatment needed
IOFTN
index of orthognathic functional treatment need
IOFTN
IOTN has limitation – severe malocclusions are not amenable to routed appliances alone
- This tries to address IOTN shortcomings
5 point scale - with Grade 5 – very great need need for Tx, Grade 1 – no need for Tx
andrew’s 6 keys use
not method of classifying occlusion - serve as a goal
Occasionally end of Tx not possible to achieve a good Class I occlusion
- Look at 6 keys to evaluate why
Andrew’s 6 Keys
Correct molar relationship
- The mesiobuccal cusp of the upper first molars occludes with the groove between the mesiobuccal and middle buccal cusp of the lower first molar
- The distobuccal cusp of the upper first molar contacts the mesiobuccal cusp of the lower second molar
Correct crown angulation
- All tooth crowns are angulated mesially
Correct crown inclination
- Incisors are incline towards the buccal or labial surface
- Buccal segment teeth are incline lingually, in the lower buccal segments this is progressive
No rotation
No spaces
Flat occlusal plane
