Orthodontics - Interceptive Orthodontics Flashcards
what is interceptive orthodontics?
Any procedure that reduces/eliminated the severity of developing malocclusion.
what will be the percentage of crowding in the permanent dentition if the primary dentition has no spacing?
66%
what will be the percentage of crowding in the permanent dentition if the primary dentition has <3mm spacing?
50%
what will be the percentage of crowding in the permanent dentition if the primary dentition has 3-6mm spacing?
20%
what will be the percentage of crowding in the permanent dentition if the primary dentition has >6mm spacing?
none
does 3.5mm of lower labial segment crowding require intervention?
no, crowding can spontaneously improve due to transverse growth across the inter-canine width.
what causes kicked out later incisor crowns? - explain
Ectopic canine
The unerupted permanent canine is leaning against the roots of the laterals, this will correct once the canines erupt
where does the upper buccal segment span from?
Distal of lateral incisor and mesial aspect of the FPM
Why at 6 y/o do 96% of patients have a diastema compared to 7% at 12 y/o?
The permanent canine erupts around this age and is much larger than the deciduous so takes up more space and rearranges the teeth.
what size of diastema is likely to close?
< 2.5mm
what causes a median diastema? (3)
- Smaller teeth
- 10% associated with Supernumerary tooth which is not interfering with eruption of adult teeth i.e. conical SN
- Missing teeth
after eruption, how long after should contralateral teeth erupt?
6 months after
what can cause upper centrals to not erupt?
- Supernumerary teeth
- Trauma = dilaceration or other pathology of the permanent successor
- Pathology
how do we treat supernumerary teeth?
- Remove the supernumerary and retained deciduous teeth
- Expose the permanent tooth (conflicting opinion over use of bonding)
- Create space
- monitor for > 1.5 years
how long should you monitor eruption after the removal of a supernumerary tooth?
1.5 years
define lee way space.
Marked difference in size between deciduous and permanent successors – especially canine and premolars
how much wider is the permanent 3,4,5 in the maxillary arch than the baby teeth?
1.5mm
how much wider is the permanent 3,4,5 in the mandibular arch than the baby teeth?
2.5mm
at what age should you take a space requirement measurement?
aged 9
where do you measure from in a space requirement measurement?
Measure from the mesial of the 6 to the distal of the 2 (same as buccal segment)
what is the ideal amount of lee way space?
18.5mm
what teeth should you balance after premature loss? (2)
C’s = balance
possibly D’s if under GA already
what causes midline shift?
premature removal of a C without balancing.
how can midline shift be corrected?
shifts can only be corrected in the permanent dentition by fixed appliances
what are the rules when extracting grossly carious unrestorable 6’s? (5)
If extracting the lower compensate by removing the upper
Treat each side separately don’t balance with a sound tooth
Remove 6’s ideally when the 7’s furcation is formed
& when the 8’s are forming
& when the premolars have erupted - 5 uses the first permanent molar to erupt into the correct position
how long does it take to correct an posterior crossbite?
6-9 months
how long does it take to correct an anterior crossbite?
6-8 weeks
why do we overcorrect posterior crossbites?
to compensate for the 50% chance of relapse
how do we prevent relapse of posterior crossbites?
Once the CB is corrected wear the appliance for a further 3 months without being activated to prevent relapse
what habit is more preferable, dummy or digit?
Dummy better then digit sucking but none have good outcomes
what are the dental outcomes of sucking habits? (4)
Proclined upper incisors
Retroclined lower incisors
localised AOB or incomplete OB
Unilateral posterior crossbite and narrow upper arch
what can be used to prevent digit sucking habits? (5)
URA Removable habit breaker – goal post
Fixed habit breakers – cemented
Behavioural management therapy i.e. positive reinforcement
bad tasting polish
dummy instead
up until what age can you remove the habit and the teeth will erupt back into the normal position within 12 months to 3 years?
10 years old
how do we manage retained deciduous teeth in the late mixed dentition?
investigate to see if the permanent tooth is present and remove the retained primary tooth
what is a submerging deciduous tooth?
where the tooth becomes ankylosed to the bone
how do we manage a submerging deciduous tooth?
If there is a permanent successor = will undergo normal exfoliation so observe for 1 year.
If there is no permanent successor = extract
when do we extract a submerging deciduous tooth?
No permanent successor and When there is 1mm of crown above the gingiva (just before it becomes subgingival)
where do permanent canines develop?
Develop palatally – just below the orbit
where do permanent canines sit in the gum?
- Labially
- Distal to the root apex of laterals
when do you start to assess a patient for canines within the gum?
palpate the gum and alveolus from the age of 10
90% are palpable by the age of 11
what do we look for when assessing if a patient canine is about to erupt? (4)
- Bulges
- Mobile c’s
- Tipped lateral incisors
- Asymmetry
if you cannot palpate a canine at age 11 what are the next steps?
radiograph OPT or Maxillary anterior occlusal
what radiographs do you take to assess an ectopic canine?
OPT
Anterior maxillary occlusal
what do you do if you identify an ectopic canine? (1)
If < 13y/o Extract the C’s
can be done up until the age of 13 – after this the dentition is established and ortho intervention is required
what impact do ectopic canines have on the surrounding dentition?
34% of lateral incisors have resorption
15% of centrals have resorption
what positioning factors determine the outcome of ectopic canine eruption? (3)
- How high up the canine is placed
- How much of the adjacent incisor is over lapped/how close to midline
- angulation of the tooth >30 degrees or horizontal = poor prognosis
what is the percentage chance of self-alignment of permanent canines If overlap is less than ½?
90% chance of self-alignment
what is the percentage chance of self-alignment of permanent canines If overlap is more than ½?
60% chance of self alignment
what causes overjets? (3)
small lower jaw
big upper jaw
(combination of both)
obtuse cranial base
how do we know if a patient with an overjet can be treated with a URA?
If they can achieve an edge to edge bite
what incisor angulation (both upper and lower) allow tipping of the teeth?
upper incisor angulation is < 120
and lower angulation is > 80
what appliances can we use in interceptive treatment of CLASS 3 ? (6)
- Functional regulator (FR)
- Frankel (FR) III – tries to change the sift tissue enviro to allow the teeth to move in the desired direction
- Rapid maxillary expansion
- Reverse pull head gear (can be used together = 70% success)
- Strong class III elastics fixed by bone screws and plates = 90% success
- Can also carry out camouflage treatment with a URA
what are the limitations of the Frankel (FR) III? (3)
- expensive
- bulky and hard to wear
- < 30% success
define camouflage treatment
Changing the incisor relationship (to class 1) whilst maintaining the natural skeletal relationship
what appliances can we use in interceptive treatment of CLASS 2 ?
- Functional appliances
- Twin block = 80% compliance
Single block appliances = 30% compliance
- Median opening activator
- FR II
- Bionator
- Headgear to restrict maxillary forward growth
what problem can occur if deciduous teeth are removed before the permanent successor is is ½ to 2/3rds developed?
delayed eruption
what are the advantages of removing the permanent 6’s at the correct time? (3)
7’s will erupt to close the space
the child will enter the adult dentition free of caries
helps to prevents crowding
what are the disadvantages of removing the permanent 6’s? (2)
Demanding in terms of cooperation for the child
May need to use GA which carries lots of risks
