Interceptive Orthodontics 1 Flashcards
Describe the occlusion at birth
Gum pads
Upper is rounded
Lower is U shaped
Often appear class II
AOB
When do deciduous teeth erupt
6 months to 2.5 years
a b d c e
Lowers before uppers
How can the deciduous dentition be told apart from the permanent?
Deciduous incisors more upright
Spacing
Wear
What is a natal/neo-natal tooth?
Abnormal dental development
Lower incisors most common
Tooth present at or just after birth
When should neo-natal teeth be extracted?
If mobile and presents a risk of inhalation
If causing difficulty with breastfeeding
What are the phases of tooth eruption?
Pre-eruptive phase - from when crown starts to form to when crown formation is complete
Eruptive phase - starts when roots start to form ends when teeth reach the occlusal plane
Post-eruptive phase - tooth movement/eruption continues as the root forms and throughout life in small increments
Describe movement in the pre-eruptive phase
Developing crowns move constantly with the jaw
Small mesial and distal movements occur
Movement of crowns is contained within the bony crypts
Describe movement in the eruptive phase?
Position of deciduous and permanent teeth alter due to eruption of the deciduous teeth and increase in height of the surrounding alveolar bone
What are the 2 stages of the eruptive phase?
Intra-osseous
Extra-osseous
What happens in the intra-osseous part of the eruptive phase?
Root formation - starts with proliferation of the epithelial root sheath and continues with the production of dentine and pulp
Movement of the developing tooth in an occlusal or incisal direction - very slow
The reduced enamel epithelium fuses with the oral epithelium
What happens in the extra-osseous part of the eruptive phase?
Crown tip penetrates through the epithelial layers - fast 1-2 weeks
Crown continues to move through the mucosa in an occlusal direction until it contacts the opposing tooth - slow
Environmental factors such as muscle forces from cheeks, lips and tongue help determine final tooth production
What is the Gubernacular cord?
Fibres formed from the dental follicle in the periphery of the eruption pathway
Theory that this guides the teeth to erupt in the oral cavity
Describe movement in the post-eruptive phase?
Movement after tooth has reached the occlusal plane
Occurs in response to increase in height of the growing alveolar bone and jaws
In response to attrition and abrasion
In response to loss of opposing teeth
What causes teeth to erupt?
Likely a combo of:
Root formation
Remodelling of alveolar bone
Development of the PDL
The dental follicle modulates cellular activity and controls a signalling cascade
What are some roles of the dental follicle?
Initiates resorption of the bone overlying the tooth
Facilitates connective tissue degradation and creates the eruption pathway
Promotes alveolar bone growth at the base of the tooth
Describe interceptive orthodontics
Utilising tooth eruption to minimise the impact of a developing malocclusion
Permanent teeth can be encouraged to erupt if the deciduous tooth is extracted when there is one half to two thirds root development of the permanent tooth
What is the definition of interceptive orthodontics?
Any procedure that will reduce or eliminate the severity of a developing malocclusion
When is interceptive orthodontics used in the early mixed dentition?
Impacted 6s
Potential crowding
Early loss of deciduous teeth
Carious 6s
Cross-bites
Transposed teeth
Habits
What are the eruption dates of the early mixed dentition?
6s - 6 years
1s - 7 years
2s - 8 years
Where do the permanent incisors develop in relation to the primary teeth?
Palatally/lingually
How is additional space gained for the larger anterior teeth of the permanent dentition?
Increase in the intercanine width through lateral growth of the jaws
The upper incisors are more proclined
The leeway space
What is the leeway space?
Upper arch - primary canine first and second molas, then permanent canines first and second premolars = 1 to 1.5mm
Lower arch - primary canine, first and second molars then permanent canine, first and second premolars = 2 to 2.5mm
What is the prevalence of diastemas?
6 years - 96% have diastema
12 years - 7% have diastema due to 3s erupted
If <2.5mm should close
Frenectomy has little effect on long term closure
What are the management options of an impacted first permanent molar?
If patient <7 wait 6 months - 90% self correct
Orthodontic separator
Attempt to distalise the first molar
Extract E
Distal disking of E
What can cause a central incisor to fail to erupt?
Supernumeraries
If patient has had trauma to primary tooth while permanent tooth is developing, causes dilaceration of root
May be other pathology
How can unerupted central incisors be managed?
Remove primary teeth and supernumeraries
Create and maintain space
Monitor for 12 months if patient <9
Expose/bond gold chain and apply orthodontic traction
What effect does early loss of deciduous teeth have?
Causes crowding
Localises crowding that is already present
Causes greater crowding in maxilla than mandible
What is balancing extraction?
The removal of a tooth from the opposite side of the arch
This maintains the position of the dental centreline and preserves symmetry
What is compensating extraction?
The removal of a tooth from the opposing quadrant
This maintains the buccal occlusion
How can early loss of deciduous teeth be managed?
Loss of A and B have little impact
Cs - balance
Ds - small shift so could balance under GA
Es - consider space maintainer
Describe a removable space maintainer?
Passive URA
Adam’s clasp on first molars
Labial bow or Southend clasps on anterior teeth
Acrylic baseplate
May have a mesial stop on individual teeth to stop drift (0.6mm HSSW)
Describe a fixed space maintainer
Palatal and lingual arches
or
Band and loop appliance
When should first molars be assessed?
8-9 years
How are first molars of poor prognosis managed?
Extraction decision based on:
Age and stage of dental development
Degree of crowding
Malocclusion type
Condition of other teeth
LA or GA?
When is extraction of first molars most ideal?
If 7s bifurcation is calcifying
If 8s are present
If class 1 occlusion or reduced OB
If moderate lower crowding
If mild/moderate upper crowding
What are the general rules for extracting 6s in a class 1 occlusion?
If extracting lower then take upper
Don’t balance with a sound tooth
Don’t balance if well aligned or spaced
If extracting upper don’t need to take lower
What should you do when assessing a posterior unilateral cross-bite
Is the patient displacing their mandible as they close their teeth together
If yes then they need treatment
If IOTN is a category 4c (midline shift of >2mm)
Describe a URA used to treat a posterior unilateral cross bite
Active component - Hyrax screw
Retention - no retention across midline, Adam’s clasps
Baseplate - posterior bite plane to disclude teeth
Why should a posterior cross bite be over treated?
They are highly prone to relapse
How can digit habits be managed?
Positive reinforcement
Bitter tasting nail varnish
Glove on hand
Elastoplast
Habit breaker appliance - fixed or removable
Describe habit breaker appliances
One piece baseplate with single goal post
Design alternative to include expansion - split baseplate with expansion screw and 2 palatal goal posts
How do you know if your patient is wearing their appliance?
Ask them
Did they walk in wearing it
Can they speak with it in
Are they still suffering from excess salivation
Does the appliance still fit
