Interceptive Orthodontics Flashcards
what does the dentition of a child at birth typically look like?
- gum pads only
- upper rounded
- lower U shaped
- often appear class II
what is the eruption order of deciduous teeth?
a b d c e
What is the most common site for a natal tooth?
lower incisors (at/just after birth)
what is the pre-eruptive phase of tooth eruption?
starts when the crown starts to form and ends when crown formation is complete/root formation about to start
what is the eruptive phase of tooth eruption?
starts as soon as the root starts to form and ends when the teeth reach the occlusal plane
what is the eruptive phase split into?
- intra-osseous stage
- extra-osseous stage
what is the post-eruptive phase of tooth eruption?
tooth movement / eruption continues as the root forms and throughout life in extremely small increments
During the eruptive phase, what do movements occur in response to?
- positional changes of neighbouring crowns
- growth of the mandible & maxilla
- resorption of the deciduous tooth roots
What occurs during the intra-osseous part of the eruptive phase?
- root formation
- movement of the developing tooth (in an occlusal or incisal direction)
- the reduced enamel epithelium fuses with the oral epithelium
what occurs during the extra-osseous part of the eruptive phase of a tooth?
- penetration of the tooth’s crown tip through the epithelial layers
- the crown continues to move through the mucosa in an occlusal direction until it contacts opposing tooth
- environmental factors such as muscle forces from cheeks, lips and tongue help determine final tooth position
What is thought to guide the teeth to erupt in the oral cavity?
the Gubernacular cord
what is the Gubernacular cord formed from?
fibres from the dental follicle
what is the post-eruptive phase of tooth eruption?
Movement after tooth has already reached the occlusal plane
- occurs in response to increases in height of the growing alveolar bone & jaws
What causes teeth to erupt?
Multifactorial, likely a combination of:
- root formation
- remodelling of the alveolar bone
- development of the periodontal ligament
- dental follicle involvement
What gene may have an influence on tooth eruption?
PTHR1 gene (parathyroid hormone receptor gene)
What are the roles of the dental follicle in terms of tooth eruption?
- initiates resorption of the bon overlying the tooth
- facilitates connective tissue degradation and creates the eruption pathway
- promotes alveolar bone growth at the base of the tooth
- provides traction forces within the periodontal ligament (special fibroblasts with contractile properties)
- ectomesenchymal cells from follicle contribute to root formation
What does interceptive orthodontic treatment involve?
The utilisation of tooth eruption to minimise the impact of a developing malocclusion
- permanent teeth can be encouraged to erupt if the deciduous tooth is extracted at the correct stage
when is the correct stage to extracted deciduous teeth to encourage permanent tooth eruption?
one half to two-thirds root development of permanent tooth
where do the permanent incisors develop in relation to the primary incisors?
palatal / lingually
Additional space is required to accommodate the larger anterior teeth of the permanent dentition, how is this space gained?
- increase in the intercanine width through lateral growth of jaws
- upper incisors erupting onto a wider arc (more proclined)
- the leeway space
what is the leeway space of of the upper arch (between primary & permanent teeth)?
1-1.5mm
what is the leeway space of of the lower arch (between primary & permanent teeth)?
2-2.5mm
What size of diastema should close on its own?
< 2.5mm
How would you treat a patient with impaction of the first permanent molar?
- if patient <7y/o wait 6 months (90% self correct)
- place orthodontic separator
- attempt to distalise the first molar
- extract E
- distal disking of ‘e’
How would a patient with an unerupted central incisor with supernumeraries be treated?
- remove primary teeth & supernumeraries
- create space/maintain space
- monitor for 12 months
still fails to erupt OR patient is > 9 y/o
4. expose/bond gold chain and apply orthodontic traction
what can early loss of deciduous teeth lead to?
localised crowding
what is a balancing extraction?
removal of a tooth from the opposite side of the same arch to maintain the position of the dental centreline (symmetry)
what is a compensating extraction?
removal of a tooth from the opposing quadrant to maintain the buccal occlusion
A patient has early loss of As and Bs, what is your treatment?
- little impact
- don’t balance or compensate
A patient has early loss of Cs, what is your treatment?
BALANCE occlusion
A patient has early loss of Es, what is your treatment?
- tend not to balance
- major space loss
- consider space maintainer
What might early loss of LRe lead to?
mesial drift of LR6
Space maintainers can be ______ or ______ ?
removable or fixed
A patient enters the surgery with first molars of poor prognosis, what factors play into your decision to extract or not?
- age of patient/stage of dental development
- degree of crowding
- malocclusion type
- condition of other teeth
- LA or GA
Extraction of first molars in a child is most ideal when?
- 7s bifurcation calcifying
- 8s present
- Class 1 av/reduced OB
- moderate lower crowding
- mild/moderate upper crowding
If you extract a lower 6, what must you also do?
EXTRACT UPPER also
How can a child with digit sucking habit be managed?
- positive reinforcement
- bitter tasting nail varnish
- glove on hand, elastoplast
- habit breaker appliance
How can you tell if your patient is wearing their appliance?
- did they walk into surgery wearing it?
- can they speak with it in
- are they still suffering from excess salivation
- can they take it in & out easily
- any signs of wear on appliance
- any gingival/palatal erythema
- tooth movement?
By what age must digit sucking habits be stopped for best prognosis?
< 9 yrs
Why should sucking habits be treated early?
- maximise potential for spontaneous correction of anterior open bite whilst there is still potential for incisors
- to prevent effects on vertical and transverse skeletal development which could lead to permanent skeletal change if habit persists
How is a digit habit managed?
- positive reinforcement
- bitter-tasting nail varnish
- glove on hand, elastoplast
- habit breaker appliance
What orthodontic appliances can be used as deterrents for digit habits?
- one piece baseplate with single goal post
- split baseplate with expansion screw and 2x palatal goal posts
What is the aetiology of infra-occluding teeth?
Ankylosis of primary tooth. Surrounding alveolar bone continues to grow. Primary tooth gets left behind
How can infra-occlusion of teeth be diagnosed?
- percussion
- check for mobility
- radiographs
In determining the presence of an infra-occluded tooth on a radiograph, what are you looking for?
- presence/absence of successor
- ankylosis of primary tooth
- root resorption primary tooth
How should infra-occlusion of a tooth be treated when the permanent successor is present?
- monitor for 6-12 months
- extract if primary tooth is below the interproximal contact point
- consider extraction if root formation successor near completion
- if extract… MAINTAIN SPACE
What are the risks of doing nothing when a patient has an infraoccluded tooth with present permanent successor?
- permanent successor can become more ectopic
- tipping of adjacent teeth (leads to hard extraction as cannot access infra-occluded tooth)
- caries and periodontal disease
How should infra-occlusion of a tooth be treated when the permanent successor is absent?
- retain primary if in good condition and consider onlay
- extract if below interproximal contact point (if extract maintain space for prosthetic tooth or reduce space with ortho)
If you are unable to palpate permanent canines by age 11 years old, what should you do?
Radiograph to check for permanent successor
How can we intercept ectopic teeth?
consider extraction of the c
When will an extraction of the c be a successful treatment option for ectopic teeth?
- patient is age between 10-13 years
- canine is distal to the midline of the upper lateral incisor
- sufficient space available
What are the risks associated with doing nothing about an ectopic maxillary canine?
- permanent successor can become more ectopic
- permanent canine then fails to erupt
- risk of root resorption of adjacent teeth
- risk of root resorption of canine crown
- risk of cyst
What interceptive treatment can be done for Class III occlusion?
Growth modification
- enhance maxillary growth / reduce mandibular growth
- protraction headgear ± rapid maxillary expansion
- patient needs to wear for 14 hours a day
Camouflage with URA
When will growth modification treatment in class III occlusions be most successful?
- mild class III
- maxillary retrusion
- anterior displacement on closing
- average or reduced lower face heigh
- patient aged 8-10 years old
Why should an increased overjet be treated early?
- risk of trauma
- appearance
- more difficult to achieve correction once patient has stopped growing
Why do we tap on the infra-occluded tooth?
Ankylosed tooth sound different on percussion (dull thud)
