W5 - Space Management - Abdalla Flashcards
What is a balancing extraction
Extract of contralateral tooth
- To preserve midline
What is a compensating extraction
Removing the opposing tooth in the other arch
- Preserve occlusal relationships
- Not indicated in primary dentition
What is an important tooth that can shift midline if lost?
Deciduous canine
Which teeth are more susceptible to hypomineralisation / hypoplasia due to timing of crown formation and eruption?
First permanent molars / 6’s
More vulnerable to caries
What can be done if 6’s have poor prognosis? Age range?
If timed correctly, extract the 6 and allow the 7 to shift into place
For upper molars - time is not as critical - 8-10 y.o. ideal for extraction
Lower molars are more sensitive to timing - extract immediately after calcification of the bifurcation of second molar
What should be considered if you are extracting a 6 due to poor prognosis?
Compensation of opposing tooth
- May otherwise over-erupt
Describe how teeth transition from primary to permanent dentition - how space is used
Think about primate spaces, early shift, late shift, differential jaw growth
Where are the primate spaces (anthropoid spaces)
Mesial to upper canine in mx
Distal to lower canine in md
What is “incisor liability”
The difference in the combined widths of permanent and deciduous incisors
Upper arch - 7.5 mm
Lower arch - 6 mm
How can incisor liability be overcome in maxilla (5)
Permanent incisors will take advantage of:
- Anterior interdental spaces
- Primate space
- They erupt labially, increasing the arch length and circumference
- Increased inter-canine width (arch gets wider)
- Reduced inter-incisal angle (incisors more proclined)
How can incisor liability be overcome in mandible (3)
- Anterior interdental spaces
- Increased inter-canine width
- Reduced inter-incisal angle
Should Angle’s classification be used in the primary dentition?
NO
- only permanent
- Ex. do not describe class I, II or III for molar relationship
How is molar relationship described in deciduous dentition
3 Types
- Flush terminal plane
- Mesial step
- Distal step
What is the most common molar relationship in decidious dentition
Flush terminal plane (76%)
>
Mesial step (14%)
>
Distal step (10%)
How does flush terminal plane transition into a class 1 molar relationship? (3)
Can occur three different ways or a combination
- Early shift
- Late shift
- Differential jaw growth
What is early shift?
if mandibular primate space is availble during eruption of the 6’s, the lower permanent molars move towards class 1
- Mesial migration of the mandibular molars, whilst mx stay in the same place
What is late shift?
Uses the leeway space to guide dentition into class 1
- Leeway space - difference between the posterior primary teeth and the permanent teeth that replace them
- 1.5 mm in the mx
- 2.5 mm in the md
What is differential jaw growth?
- Mandible grows more forward relative to maxilla in transition from mixed to early permanent dentition
- If lower jaw grows more forwards, then lower jaw carries lower teeth further forward relative to upper teeth
What tool can be used to maintain Leeway space? (3)
Lingual Holding Arch
- Bands on 6’s
- Wire rests on the lingual surfaces of anteriors
- Contraindicated until permanent incisors have erupted (otherwise may interfere with eruption)
What should be done for the premature loss of primary canines
- Balance the extractions
- Place lower lingual arch to prevent space loss
What should be done for the premature loss of primary molars? (2)
- Lingual arch resting against incisors
- Band and loop appliance
Pro and con of band and loop appliance
Easy to use → can be fabricated and placed chairside at the same visit
However, if abutment tooth is lost - space is lost
Is space maintenance appropriate for all children?
No - they increase caries risk and take time (up to a few years)
In high caries risk pts - should be avoided
Whats wrong here?
Early loss of deciduous second molars
Examples of space management appliances (3)
