Interceptive ortho 1 Flashcards
What is the eruption of descidious teeth
A B D C E
Whe would extraction be indicated for natal/neo-natal teeth
If
-mobile and presents a risk of inhalation
-is causing difficulty with breatfeeding
Whar are the 3 phases of tooth eruption
Pre eruptive
Eruptive
Post eruptive
What does the pre-eruptive phase start and end
starts when the crown starts to form and ends when crown formation complete / root formation about to start.
When does eruptive phase start and end and what are the 2 stages its split into
starts as soon as the root starts to form and ends when the teeth reach the occlusal plane
Split into intra-osseous stage and extra-osseous stage
When does the post-eruptive phase start
tooth movement / eruption
continues as the root forms and throughout life in
extremely small increments
What happens in the pre-eruptive phase
The developing crowns move
constantly within the jaws
Small mesial and distal tooth
movements occur
The developing crowns reposition themselves in response to increasing length , width and height
of the jaws
Movement of tooth crowns is
contained within the bony crypts
What happens in the eruptive phase
Relative position of deciduous and permanent teeth alter due to eruption of the deciduous teeth and increase in height of the surrounding alveolar bone
Movements in the eruptive phase occur in response to what
- Positional changes of neighbouring crowns
*Growth of the mandible and maxilla
*Resorption of the deciduous tooth roots
What happens in the Intra-osseous stage 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 (slow - several months)
- The reduced enamel epithelium fuses with the oral epithelium forming the junctional epithelium which then starts to thin out
What happens in the extra-osseous stage of the eruptive phase
- Penetration of the tooth’s crown tip through the epithelial layers (fast 1-2 weeks )
- The crown continues to move through the mucosa in an occlusal direction until it contacts the opposing tooth (slow -several months)
- Environmental factors such as muscle forces from cheeks, lips and tongue help determine final tooth position
What is the eruption pathway
Within the Dental follicle degeneration occurs.
Blood vessels decrease in number, nerve fibres
break up into pieces. The resulting area becomes known as the eruption pathway
What is the Gubernacular cord
In the periphery of the eruption pathway other fibres are formed from the dental follicle
this guides the teeth to
erupt in the oral cavity
What happens in the post-eruptive phase and why does it occur
Movement after tooth has already reached the
occlusal plane
-Occurs in response to increases in height of the growing alveolar bone and jaws
-In response to attrition and abrasion (teeth erupt slightly to compensate for wear on occlusal surfaces, proximal surface tooth wear leads to mesial drift)
-In response to loss of opposing teeth = over-eruption
What causes tooth eruption
Multifactorial
- Root formation
- Remodelling of the alveolar bone
- Development of the periodontal ligament
What plays a key role in
modulating cellular activity and how
dental follicle
It is believed that signalling takes place between the
dental follicle and the reduced enamel epithelium
Tooth eruption is controlled by a signalling cascade of
cytokines (including Interleukin1, CSF 1, RANKL/
Osteoprotegerin pathway)
What is interceptive orthodontics
Any procedure that will reduce or eliminate the severity of a developing
malocclusion
In mixed dentition what could go wrong
- Impacted 6’s
- Potential crowding
- Early loss of deciduous teeth
- Carious 6’s
- Cross-bites
- Transposed teeth
- Habits
How do the permanent incisors develop to the prim teeth
palatally/lingually to them
What is needed to accommodate the larger Ant. perm. teeth
Space
How is space gained for the larger Ant. perm. teeth
Increase in the intercanine width through lateral growth of the jaws
The upper incisors erupting onto a wider arc
The leeway space
What is the leeway space
The difference between the sum of the mesiodistal crown widths of the primary canines and molars and that of their successors, the permanent canines and premolars
What is the leeway space values for the upper arch normally
(prim. canine+first molar+second molar)-(permanent canine+first premolar+second premolar)
= 1 to 1.5mm
What is the leewayspace avlues normally for the lower arch
(primary canine+first molar+second molar)-
(permanent canine+first premolar+second premolar)
= 2 to 2.5mm
What % of 6 years olds and 12 years olds have diastema
and how much should close
6 years old- 96%
12 years old- 7%
<2.5mm should close
What is ectopic eruption
The permanent first molar gets stuck beneath the ‘e’ and fails to fully erupt
How is ectopic eruption managed
- If patient <7years wait 6 months (90% self correct)
- Orthodontic Separator
- Attempt to distalise the first molar
- Extract E
- Distal disking of ‘e
What can cause unerupted central incisors
Supernumeraries
Trauma to primary= tooth Dilaceration of permanent tooth
Other pathology
If an unerepted central incisor is due to supernumerary tooth how do you deal with it
- Remove primary teeth &
Supernumeraries - Create space/maintain space
- Monitor for 12 months
If patient < 9 years (immature root apex)
(Still fails to erupt? OR patient >9 years, mature root apex)
- Expose/bond gold chain and
apply orthodontic traction
How would you manage early loss of desicidous teeth
Balancing Extraction = removal of a tooth from the opposite side of the same arch
Why?
To maintain the position of the dental centreline
(preserve symmetry)
Compensating Extraction = removal of a tooth from the opposing quadrant
Why?
To maintain the buccal occlusion
How would you deal with early loss of each descidious tooth
A’s & B’s= little impact dont do anything
C’s= balance
D’s= – small CL. shift,
balance under GA maybe
E’s= tend not to balance, major space loss, upper>lower
-Consider space
maintainer
When would be best to extract carious 6’s
- 7’s bifurcation calcifying
- 8’s present
- Class 1 av/reduced OB
- Moderate lower crowding
- Mild/moderate upper crowding
What are the general rules when extracting 6’s
If extracting lower take upper
Don’t balance with sound tooth. Don’t balance if well aligned or spaced.
If extracting upper don’tneed to take lower
