Revision lecture Flashcards
Up to what % disposition do pts of an increased overjet have to trauma?
50%
Why do class II div I have an increased risk of trauma to their upper anterior teeth?
Proclined teeth with lost support of the lips (lip incompetence) leave them more at risk
What 2 qualities would an alternation in transverse skeletal relationship lead to intra-orally?
Centre-line shift
X-bite
What is a scissor bite?
Ginormous upper jaw, relatively normal lower jaw
Upper jaw significant placed buccal to lower, no occlusal contact
Which incisal relationship is a scissor bite classically seen in?
Class II div II
What are the 3 categories of crowding
Mild crowding: 1-4mm
Moderate: 5-8mm
Severe crowing >8mm
What is the definition of an incisal relationship of class II div I?
Lower anteriors lie posterior to the cingulum plateau of the upper incisors with an increased overjet
What is the definition of an incisal relationship of class II div II?
Upper central incisors are retroclined with sometimes a reduced overjet
Name an approach for assessing a dental panoramic
- Presence/absence of teeth (supernumeries? hypodontia?)
- Developmental position of teeth & abnormalities of eruption (maxillary canines? infraocclusion?)
- Presence of disease
- Presence of pathology
- Normal anatomy
What are odontomes?
benign tumor-like growth made up of dental tissue that resembles abnormal teeth
A compound odontoma has a tooth-like structure and is arranged in a uniform manner, similar to a normal tooth, while a complex odontoma has a mixed structure of disorganized tissue mass
What 4 things do we assess when considering the prognosis of ectopic canines?
- X - height from occlusal plane (closer the better)
- Y - proximity to midline
- Z - angulation of the canine/long axis obliquity (lower the better)
- Labial/palatal positioned (parallax)
What can a lateral cephalogram radiograph conclude in orthodontics?
Quantify the severity of the skeletal discrepancy
Assess jaw bases in relation to anterior cranial base
Assess each jaw base in relation to one another (eg ANB/MMPA)
Assess relationship of dentition to jaw base
Which type of malocclusion is an adaptive tongue trust most common in
Anterior open bite
Tongue fills gaps and pushes forward to create an anterior oral seal
What is dento-alveolar disproportion?
Disproportion between the size of the jaw and number of teeth
Either spacing or crowding
What is the aetiology of crowding?
Dento-alveolar disproportion
Not enough jaw space for the number of teeth
What could be a differential diagnosis of a midline diastema?
Early forming/ conical / mesiodens supernumery teeth
What are the characteristics of conical supernumery teeth?
Offshoot of the dental lamina
Develop between 1/1
Sing/multiple; erupt unless inverted
No effect or cause crowding (increased dento-alveolar disproportion) /diastema
XLA if interfere w ortho tx
What length of time does it become a concern if a contralateral permanent tooth doesn’t erupt?
6 months
Which type of supernumery impedes eruption?
Tuberculate
Prevents eruption of the incisors
Where do tuberculate (late forming) supernumerys commonly form? Do they commonly erupt?
Palatal of upper 1/1
Rarely erupt
Whats the tx of a tuberculate supernumery impeding eruption of the upper incisors
XLA primary teeth and supernumery
Ensure adequate space
75% will erupt spontaneously
Can surgically remove overlying bone &/or E&B w gold chain
How does a supplemental supernumery originate?
Dichotomy of the tooth germ
What is the tx for a supplemental supernumery?
XLA most displaced tooth
What dental characteristics does digit sucking cause?
AOB/ reduced or incomplete OB
Buccal X bite
Class II Div I incisor relationship
(retroclination= crowded lower, proclination= spaced upper)
Centre-line discrepancy (thumb rarely in midline)
Adaptive tongue swallow
Digit deformity (thumb will look like a finger not a thumb)
What are the indications for tx of a AOB?
Note: tx rarely done for TMJD unless x bite w displacement
What are the aims of tx of a AOB?
Relieve dental crowding & align teeth
Reduce the overbite & overjet
If a tooth has had a history of trauma, what would need to be ensured prior to starting ortho tx involving that tooth?
It is stable?
Minimum 6 months before starting ortho tx, as otherwise this can accentuate trauma/ loose vitality of teeth involved in trauma
Warn of risk/loss of vitality
What are the dental health components of the IOTN?
M issing teeth (impacted teeth)
O verjet ( >+6mm; >-3.5mm)
X -bites (displacements >2mm)
C ontact point displacements (>4mm)
O verbite with trauma
In order of priority
In ortho tx plans involving extractions, the choice of tooth to be extracted is determined by…
The dental health of those teeth
Poor prognosis: gone first
How do we decide whether to use fixed or rem appliances?
Any rotations? Severely displaced teeth?
-> fixed appliances
(bodily tooth movement v simple tipping)
How do we consider whether an ortho tx plan should contain extractions or not?
Plan tx around lower arch
If crowding >4mm, extractions likely
Lower arch require extractions? Most likely upper too then (9/10)
Why do maxillary canines become ectopic?
Longest path of eruption
Longest path of development
Microdont/missing lateral incisor
Genetic
What guides the maxillary canine into position during eruption?
The lateral canine
What prevalence of ectopic maxillary canine is there?
2%
What are the tx options of ectopic canines?
Interceptive: extract c/c to normalise the path of the 3’s
This is not always successful
What factors influence later treatment of ectopic canines?
Presence/absence co-existing malocclusion
Prognosis of canine
Pt’s attitude of tx
Age and PMH
What are the tx options for ectopic canines?
No tx (inherent risks -resorption of 2 & 4 roots; c will fall out and gap present)
Surgically remove canine (gap present when c falls out
Surgically expose comprehensive orthodontics- bonded attachment (open/closed exposure)
Autotransplantation
If there is a x-bite, you always test for a…
Displacement
When regarding x-bites, what is indicated for it to be treated?
Crossbite WITH displacement
Aesthetics- facial and dental
Dental- pain and wear
Periodontal- loss of attachment
TMJD
Risk of developing a true asymmetry
Displacements may mast true extent skeletal pattern
How do we assess a pt’s displacement?
Put pt into RCP/see if they can achieve edge to edge
Then assess difference in natural position- this is the displacement
Can be forward displacement (esp in anterior x bites)
Can be lateral displacement (esp in posterior x bites)
What does a x bite without a displacement indicate?
True skeletal discrepancy
Wat are the 4 components of a rem appliance?
Active (z or t springs- made from 0.5mm stainless steel)
Retentive (aadam’s clasps- tooth born; crib the 6’s,4’s or D’s)
Anchorage (n of teeth being moved must be sig less than the n of teeth not being moved to ensure it is moved in right direction)
Base-plate (acrylic cold cure or heat cured if need extra strength); split screw can be incorporated if expansion is needed
Name a functional appliance
Twin block
What characteristics would you look for to treat a pt with a functional appliance?
Skeletal II
Big overjet
Growing patient (G-10-12yr;B-12-14yr)
What is a trans palatal arch?
Used for anchorage
Holds the upper molars in place, can reposition them further back/correct rotations
How does a functional appliance work?
Growth modifications
3 modes of action:
- Skeletal (30%)- hold maxilla back) and encourage mandible to grow forward
- Soft tissue- lower lip sits in front of upper incisors due to mandible growth forward
- Dentoalveolar (70%) - tipping/retroclining upper incisors and proclining lower incisors
