9- retention and relapse, iatrogenesis

What is relapse?

Any change from the final position achieved at the end of treatment- loss of correction

Usually moves toward original malocclusion

What is retention?

holding the newly moved teeth in place long enough for the correction to stabilise

Who dictated the 4 thoughts of school?

Occlusion- Kinsley

Apical base- Lundstrom

Mandibular incisor- Grieve and Tweed

Musculature- Roger’s

What are the 4 schools of thought that help prevent relapse?

Occlusal- achieve proper intercuspation and interdigitation- cusp to fossa relationship

Apical base- avoid changes to intercanine/intermolar widths and increase arch length minimally

Mandibular incisor- placed upright and over basal bone

Musculature- proper balance

What are 5 causes of relapse?

Periodontal and Gingival Factors

Occlusal Factors- better quality occlusal finish- less relapse

Soft Tissue Pressures- if teeth moved far out of neutral zone, bigger change in arch form, old age- more unstable

Growth

Pressure from 3rd molars- not much evidence

How do periodontal and gingival factors contribute to orthodontic relapse? (4)

Periodontium must remodel after tooth movement

Most collagen fibers reorganise in 3–4 months

Dentogingival and interdental fibers take 8 months

Must be held in correct place until remodelling- especially after rotational correction

How can you reduce rotational relapse?

Pericision- surgically sever supracrestal fibres (fibreotomy)- removes elastic forces that cause the tooth to rotate back

How can late mandible growth cause relapse?

Late lower incisor crowding due to forward mandibular growth.

Mandible displaced distally- rare, may relate to myofascial pain/TMJ dysfunction

Flaring/spacing of upper incisor- least common

Distal displacement and crowding of lower incisors with a decrease in intercanine width

How can you identify patients who will suffer replace?

Impossible- must treat all patients as if they can relapse

Informed consent before- unpredictable nature, life long retention to reduce risk

For what 6 cases do we need semi/permanent retention?

Midline diastema

Severe rotations

Arch expansion achieved without ensuring good occlusion

Some class II div 2 deep bite cases

Have abnormal musculature or tongue habits

Expanded arches in cleft palate patients

How long is Harley’s retainer worn for?

6 months full time then part time at night

When is Begg’s retainer used?

Need to settle occlusion- no wire framework across teeth

Which removable retainer corrects rotations?

Clip on/spring retainer

Runs labial and lingual

Wrap around retainer is an extended version- covers all teeth

When is a fixed retainer indicated? (5)

Hold diastema closed- bonded to selected teeth

when final position unstable due to-

Periodontally compromised support

Malocclusions with spacing

Severe rotations

Lower labial segment moved during treatment

Adverse Iatrogeny effects of orthodontic treatment include… (6)

Root effects

Coronal effects

• Malpositions

• Bonding

Periodontal effects

Post-surgical effect

TMJ effects

Psychological effects

What are some adverse root effects caused by ortho treatment?

Pulp effected- vitality loss due to traumatic occlusion or excessive (intrusive) force or uncontrolled coronary lingual torque

Mobility and pain- some mobility normal

Root resorption- apex rounding

Biological (7) vs mechanical factors (4) causing root resorption

What are 3 adverse crown effects of orthodontic treatment?

Caries

Accumulation of plaque

Premature contacts

How can effect of debonded braces in enamel adversely effect crown? (4)

White / yellow spots

Cavitations

Bonding material remains

Effect of the bur on the enamel when removing brackets

What can cause adverse periodontal effects? (4)

Badly adjusted bands

Bands with gingival overflowing bond

Periodontal effect

Recessions

What are 5 adverse mucous effects of orthodontic treatment?

Traumatic ulcer-

Acute

Chronic reactive

Traumatic granuloma

Frictional or focal hyperkeratosis