Retention and relapse Flashcards
Define retention and relapse
- Retention: the phase of orthodontic treatment that attempts to keep the teeth in the correct position after braces
- Relapse: tendency for the teeth to move back to their old positions after orthodontic treatment
State three reasons why retention is important
It helps:
• Keep gingival and periodontal tissues in the correct position long enough so that they can eventually remodel into the correct positions
• Resist the unbalanced soft tissue forces (oh cheeks, lips, tongue) post treatment (neuromuscular adaptation)
• Counteract changes produced by continued growth
List and briefly describe aetiological factors for relapse, specifically the ones for (8):
- Age
- Arch form width
- Periodontal soft tissue forces
- Neuromuscular forces
- Initial malocclusion (deep bites, class II, rotations)
- Functional habits (digit sucking, tongue thrusting)
- Third molars (probably, evidence is not solid on its negative effect)
- Post- treatment tooth position
Focus:
• Age (got to do with growth potential and this effect on occlusion. In addition, older patients have reduced periodontal support = higher relapse)
• Arch form and width (the need for arch expansion. Sometimes, arch expansion may not stay)
• Periodontal/ tissue forces (it takes time for these to remodel. Doing treatment too fast will not allow these tissue to have enough time to reorganise itself. In addition, lowered periodontal support and bone loss will lead to relapse)
• Neuromuscular factors (important for teeth to sit in a zone where the forces of lips, cheeks, tongue and occlusion are balanced)
List the types of retention used for a class II malocclusion
- Functional appliances (removable brace that works on the upper and lower teeth at the same time). Examples are bionator, activator and twin block
- Headgear (connects to mouth via molar band on 6’s or plates)
List the types of retention used for a class III malocclusion
- Reverse pull headgear. Causes skeletal and dental changes. It can treat overjet. Worn at night time
- Functional appliances (removable brace that works on the upper and lower teeth at the same time)
- They have reverse function to class II FA, i.e, they pull the maxilla forward and push the mandible pack ward
- Type of FA can be a class III twin block, class III bionator
List the types of retention used for a deep bite/ overbite
- Retainer with anterior bite plane. This prevents re- eruption of incisors
- Retention for deep bites are usually done by originally treating the bite via overcorrecting it and giving the proper inter- incisal angulation
List the types of retention used for an open bite
- High pull headgear
- Retainer with posterior occlusal coverage. This uses muscles to prevent posterior over eruption
- Again, it is treated with over correction
List the standard forms of retention (5)
Fixed lingual retainer
Essix retainer/ Vacuum Formed Retainer (VFR)
Hawley
Spring aligner
Positioner
Describe fixed retainers in terms of:
- What it is
- Where it is placed (why it is placed)
What it is
· Thin metal wire bonded on the lingual surfaces of the front teeth
Where it is placed and why:
· Lower arch: usually 3-3 but can extend to the second premolar in first premolar extraction case
· Upper arch: difficult to place in some cases. If used, usually 2-2, can extend to the canine if the canine was really out of alignment or ectopic
Briefly describe removable clear plastic aligners in terms of:
- How it is made
- How they are used
- What type of movements they are most effective for
- How it is modified for better teeth movement
How it is made:
• 3D modelling software and highly accurate dental impressions
• A series of removable aligners are made
How they are used:
• Straighten teeth but are removable
• Each aligner is made for approximately 2 weeks
What type of movements they are most effective for:
• Effective in tipping movements
How it is modified for better teeth movement:
• Composite resin attachments can be bonded to teeth for more controlled teeth movement
For Hawley retainers, state the purpose of:
- labial bow
- clasps on the molars
- palatal coverage
- anterior bite plane (optional)
- posterior bite block (optional)
- labial bow: control incisors angulation/alignment and provides retention
- clasps on the molars: retention
- palatal coverage: hold transverse expansion
- anterior bite plane (optional): prevent lower incisors eruption and maintaining the deep bite correction
- posterior bite block (optional): prevent posterior teeth eruption and maintaining the closure of open bites
Describe the spring aligner, in terms of:
- Location it is used for
- Composition
Location:
• Usually used on anterior teeth, especially lower ones
• Can allow mild alignment correction
Composition:
• Made of wire and acrylic contoured to labial and lingual surfaces of teeth
Describe positioner retainers in terms of:
- What it made of
- When it is used
- Advantages
- Disadvantages
What it is made of:
· Made of elastic material (usually polyurethrane) where maxillary and mandible plates are connected
When it is used:
· Can be used as a finishing device and a retainer
Advantages:
· Massages the inflamed gingival tissue and is good in open bite cases
Disadvantages:
· Bulky, people do not comply with it
List the advantages (1) and disadvantages (3) for fixed lingual retainers
Advantages
· Not visible, comfortable for the patient. It doesn’t require compliance from the patient
Disadvantages
· Potential hygiene issues
· Wire debonds, which the patient may not notice, it can cause relapse
· Risk factor for demineralization/ calcification
List the advantages (6) and disadvantages (4) for essix retainer/ Vacuum Formed Retainer (VFR)
Advantages • Cheap and easy to make • Aesthetic • As good as Hawley for retention • Good for minor teeth correction • Good patient acceptability • Good compliance
Disadvantages • Wear and breakages • Too flexible for transverse retention (maxillary expansion) • Not good for occlusal settling • Compliance
