9 - Fixed Appliances and innovations in appliances Flashcards
LO
The stages in the straight wire appliance treatment are:
- Aligning
- Levelling
- Space closure
- Finishing
Don’t need to memorise for BDS
Sectioned Mechanics:
- Two archwires
- Bioprogressive
- Rickets
- Burstone t loops
Different to straight wire appliance
Andrew’s 6 Keys:
- Molar Relationship
- Tip
- Torque
- Rotation
- Spacing
- Curve of Spee
These are the areas that orthodontic treatment needs to address for successful treatment. It is not always possible to achieve all 6 keys in every patient.
Bracket Positioning:
(For straight wire technique, brackets should be placed appropriately)
- Edgewise brackets are placed at determined distance from the occlusal surface.
- Andrews: Midpoint of the long axis of the clinical crown
- FA point
- Except molars
- Where is the midpoint? Torque values change with bracket positioning - MBT: Dougherty gauges
Prescriptions
What is this
List 3 main prescriptions
Size of bracket slot can be:
Prescriptions – The bracket slot that is cut in the bracket has different tip torque and rotation. This is known as prescription:
1. Andrews
2. Roth
3. MBT (McLaughlin, Bennet, Trevisi)
Size can be 018 or 022 system
What are 1st, 2nd and 3rd order bends?
Movement of the teeth is described as 1st, 2nd and 3rd order bends
1st Order: Movement ‘in/out’ and rotations
2nd Order: Tipping
3rd Order: Torque
Torque - expression ‘slop’
When you use wires that go in the bracket slots, the wires increase throughout the treatment.
Throughout treatment, as there is less and less space between the wire and the bracket slots, a phenomenon called slop occurs, where the bracket does not fill the prescription, therefore it will not express the prescription fully
CHAGPT explanation:
- Slop occurs when the wire is smaller than the bracket slot, leaving extra space.
- This prevents the bracket from fully expressing its built-in prescription for tip, torque, and rotation.
- As wires get thicker, slop decreases, and the teeth move closer to the ideal positions.
Stages of straight wire appliances - Aligning
1- How are labial and buccal segments aligned?
2- How is de rotation or over rotation managed?
3- How are upper incisors in crossbite with lower incisors managed?
1-
• Labial & buccal segments
– include all teeth initially
– create space first, then include working AW push-coil, ‘pull’ mechanics
2-
• De-rotation/Over-rotation
– Undertie, Overtie, lingual cleats/buttons
– Steiner Wedges, Rotation Wedge
3-
• Upper incisor(s) in x-bite with LLS:
– if bracket in the way, debond and reposition
– ‘back to front’ power chain
Wires: Alignment
What type of wires are used in fixed appliances for alignment:
1-
Formable wires:
- Looped wires
- Multi-strand wires - Braided, Coaxial or Three strand twist
- NiTi (Variable force)
Some have Perfect shape memory – Impossible to permanently deform the wire using orthodontic
forces:
- Thermally active NiTi wires
- CuNiTi
Rotations
What can be used to de rotate teeth?
• Undertie
• Steiner Wedge
• Rotation Wedge
For rotations
Vertical control: Bite opening
If patient has a deep bite, need to open bite:
• Temporary
• Sectional
• Levelling in the continuous arch
• Elastics
Upper Teeth in Crossbite with the Lower Arch
What could happen?
What is the solution?
• Bracket of tooth in crossbite might be bitten off therefore posterior bite opening
• Solution: Back to front power chain
Pt left premolar in cross bite and right lateral incisor is in cross bite - so can put bracket on inside of the incisor and an elastomeric chain
What can you see here?
Mixture of fixed and removable appliance
Can see Southend clasps - on upper incisors
But also fixed to align the canines - has been surgically exposed and pulled down by power arm
What is this
What is it used for
Bite turbos
Used to open deep bites - Bite opening
What is this and its use?
Secondary arch wires
Very thick upper wire on top of the standard wire - can be used to expand or contract
What’s this and use?
Rapid maxillary expander
Opens the bite
Screw turned a few times a day so mid palatal suture opened and rapid expansion is achieved in a few weeks
Bite opening: as sectional technique
He said just to list not memorise?
What’s this?
Secondary arch wire - this case is maxillary arch wire used to open bites
Brackets usually placed?
Middle of the tooth
But sometimes may be placed elsewhere eg more incisally on front teeth and more gingival on back teeth can lead to bite opening
What’s this
elastic
This is class II elastics- pull upper anterior segment back and push lower posterior segment forward
Can also be sued to treat vertical discrepancy
Wires: Space Closure
What wire is used to:
Move single teeth along an arch wire
Space closure and over bite control
Space closure: Anchorage, Friction and Frictionless mechanics
Single tooth and blocks of teeth can supply anchorage
Single root and smaller roots provide less anchorage than multirooted teeth.
What can you see
If friction is too great to move segments of teeth for space closure what can be used?
Looped mechanics
Friction vs frictionless mechanics - for understanding
Unsure if correct- answer is from CHATGPT
In friction mechanics, the tooth moves by sliding along the archwire, creating friction between the wire and the bracket slot or ligature - eg elastics, power chains
In frictionless mechanics, there is minimal or no contact between the archwire and bracket during tooth movement, eliminating frictional resistance.
• Commonly achieved using loops
Finishing
- First order – Rotation/in out
- Second – Angulation/tip
- Third order – Torque
- Vertical – Occlusion
- Tooth size and shape
Wires used in Finishing:
Could be any below used in an appropriate way
Patient at finishing stage - 6 keys have been achieved
No spaces
No rotations
Good tip/ torque and buccal segment relationship
6 keys
For improved aesthetics for fixed what can be used?
- Conventional appliances: Improved Aesthetics - Ceramic or composite brackets
- Self ligation
Overview of orthodontic techniques
- removable
- Fixed:
1. Labial - Tip/torque/ rotational/ vertical control
- standard edgewise
- SW (sectional/ segmental)
- Begg
- Tip - Edge
2. Lingual - mixed
CAD/CAM in Orthodontic Treatment – Simulated Tooth Movement:
- Aligners
- Lingual Appliances – Individualised bracket design and indirect bonding
Aligners steps
What do you need to provide aligners
- Impression (Scan)
- Treatment Plan Submission
- Postage (Documents)
- Clinical Check
- Fitting
- Attachments
- Speech impact?
Need:
Courses for ‘registration’ and teaching
Forms and advices
Add set photos and radiographs
0.25mm movement per aligner
Question on how effective they are on Torque, Intrusion, Extrusion, and Bodily Movement - may not be suitable for complex
Example of pt eligible for aligners
Normal occlusoin with good interdigtated class 1 buccal segment relationship LHS, RHS slightly post normal with some irregularity affecting both upper and lower arches
Click answer
Lingual fixed appliances
List the types:
List 6 disadvantages
1-
- Prefabricated
- Wire bending
- Individualised
- Acrylic interface
- Thin (wire bending)
- Thick (predetermines wire shape)
- Individually cast (CAD/CAM)
2-
- Preop costs
- Special pliers
- Speech problems
- Lingual ulcers
- Failure rate
- Difficulty with repairs
Lingual fixed - bonding technique
Bonding technique - indirect
Repairs challenging
Specific materials needed
Lingual fixed
Lingual attachments mechanics:
Lingual Fixed
List 4 issues with individualised lingual fixed:
- cost
- upfront charge to operator
- chair side time
- setup
Unsure make slide below part of Q?
Prefabricated lingual appliances on the left
Individualised lingual appliance on right - smaller than prefabricated
Simple treatment : directt lingual
Apply fixed appliance directly with plier
For understanding prev FC required lab and CADcam
