Interceptive Orthodontics 2 Flashcards
What should be assessed in anterior cross bites?
Displacement
Mobility of lower incisors
Tooth wear
Gingival recession
What active component is used to correct an anterior open bite?
Z-spring (double cantilevered spring) 0.5mm HSSW
How stable are cross bite corrections?
Anterior - may cause overbite
Posterior - 50% relapse
Why should cross bites be treated early?
To maximise potential for spontaneous correction while there is still eruptive potential for incisors (8-10 years)
To prevent effects on skeletal development which could lead to permanent skeletal change if habit persists
What teeth are commonly infra-occluded why?
In 10% of people
Lower more than upper
Possibly due to permanent absent successors
Describe the aetiology of infra-occluding teeth
Ankylosis of primary tooth
Surrounding alveolar bone continues to grow
Primary tooth gets left behind
How is an infra-occluding tooth diagnosed?
Percussion
Check for mobility
Radiographs (PA or OPT)
What should radiographs be assessed for in infra-occluding teeth?
Presence/absence of successor
Ankylosis of primary tooth (no PDL space/no clear lamina dura)
Root resorption of primary
What should you do with infra-occluding teeth if the permanent successor is present?
Monitor for 6-12 months
Extract if primary tooth is below the interproximal contact point
Consider extraction if root formation of successor is near completion
If extracted - maintain space - most important in upper arch
What should you do with infra-occluding teeth if the permanent successor is present?
Monitor for 6-12 months
Extract if primary tooth is below the interproximal contact point
Consider extraction if root formation of successor is near completion
If extracted - maintain space - most important in upper arch
What are the risks of doing nothing to an infra-occluded tooth?
Permanent successor can become more ectopic
Infra-occlusion worsens with tipping of adjacent teeth - primary tooth becomes inaccessible for extraction
Caries and periodontal disease
What should you do with an infra-occluding tooth if the permanent successor is absent?
Tx plan depends on degree of crowding, degree of infra-occlusion and any other malocclusion features
Retain primary if in good condition and only extract if below interproximal contact point
Describe normal development of upper canines
Development starts high and palatally
Migrates and lies labial and distal to the root apex of upper laterals
90% are palpable by 11 years
Mobile symmetry of Cs
Angulation of lateral incisors
When should eruption of upper canines be assessed?
9-10 years onwards
Radiograph if unable to palpate by 11 years
What are the consequences of ectopic maxillary canines?
Resorption of:
Central incisors in 15%
Lateral incisors up to 66.7%
Most root resorption occurs before age 13
How are ectopic maxillary canines intercepted?
Extraction of the Cs
When is extraction of Cs for ectopic maxillary canines most successful?
Patient aged 10-13
Canine is distal to the midline of the upper lateral
There is sufficient space available
What are the risks of doing nothing for ectopic maxillary canines?
Permanent successor can become more ectopic
Permanent canine then fails to erupt
Risk of root resorption of canine crown
Risk of cyst formation around canine
Permanent canine can become ankylosed
How should a reverse OJ be assessed?
Assess whether the patient can achieve an edge-edge relationship
Assess if the mandible displaces on closing
What are the interceptive treatment options for a class III occlusion?
Growth modification:
Enhance maxillary growth and/or reduce mandibular growth - protraction headgear and possible rapid maxillary expansion or functional appliances such as reverse twin block
Or camouflage with URA
When is growth modification in class III occlusion most successful?
Skeletal I or only mild class III
Maxillary retrusion
Anterior displacement on closing
Average or reduced lower face height
Patient 8-10 years
When is growth modification in class III occlusion most successful?
Skeletal I or only mild class III
Maxillary retrusion
Anterior displacement on closing
Average or reduced lower face height
Patient 8-10 years
When does a patient need to wear protraction headgear?
14+ hours a day
When is bone anchored maxillary protraction used and what is the success rate?
Bollard Implants
Used in the late mixed dentition
90% success rate
