Adams Clasp Flashcards
What is the role of an Adams clasp?
Retention:
helps keep in appliance
engages undercut on mesial and distal surfaces
What is an adams crib made of?
0.7mm diameter stainless steel wire
= engages 1mm of under cut (in children where teeth not yet fully erupted it engages below the gingivae)
N.B. uses 0.6mm wire on premolars
What are the elements of a removable appliance?
Active components
Retentive components
Anchorage
Baseplate
What is retention?
The capacity of an appliance to remain fixed in the mouth = needs an undercut
What are the possible different forms of retention for a removable appliance?
Posterior teeth = adams clasp
Anterior teeth = southend clasp & labial bow (these both also keep the teeth in the right place and prevent tipping)
What is the role of the baseplate?
Keeps the components in the right place
Collets
What are southend clasps made of?
0.7mm stainless steel wire
What are (reversed loop) labial bow?
0.8mm stainless steel wire
What is a baseplate made from?
Acrylic resin (autopolymerising/self cure)
Why are adams clasps rarely used on anteriors and canines?
Theres not very much undercut to engage = not very retentive
What are the component parts of an adams crib?
- A bridge
- 2 X Arrowheads
- 2 X flyovers
- 2 X tags
What is the purpose of the tags?
So there is a small amount of space below the wire on the palate for the resin to flow under to hold the whole thing in place
What do the arrow heads do?
Engage the undercuts
In an adams crib which palatal clasp needs to curve towards the other? and why?
The distal arm to keep it within the baseplate
What are the common faults of adams cribs?
- Bridge too low
- Bridge too short
- Arrowheads too small (bridge too close)
- Arrowheads too low
- Flyover too high
- Flyover not close enough to distal of tooth
- Retention tags too close together
What is the problem with a bridge that is too low?
There’s no room for adjustment
How far up a tooth is the bridge meant to be?
2/3rds of the way up the crown
What is the problem with a bridge that is too short?
The arrow heads flare at the wrong angle, they need to dip in to engage the undercut
What is the problem with having bridges that are too small?
The arrowheads are too upright so dont engage the undercut
What is the problem with having undercuts that are too low?
Tissue trauma
What is the problem with having a flyover that is too high?
It interferes with occlusion (n.b. this can be adjusted)
Faults in which parts of an adams cribs cannot be adjusted and need to be redone completely?
The arrowheads and bridge (sharp bends fracture when rebent)
What is the problem with the distal flyover being too far from the tooth?
Interrupt with eruption of second molar
What is the problem with the retention tags being too close together??
Resin cannot flow between them and hold them in place properly
