1. Aetiology and extractions Flashcards
Describe the main aetiological factors in malocclusions
- GENERAL FACTORS
- SKELETAL RELATIONSHIP
- TOOTH SIZE / ARCH SIZE DISPROPORTION
- soft tissues
- genetic and developmental disorders
- TMJ trauma / growth abnormalities
- LOCAL FACTORS (more important to us as they are the ones we can identify and prevent/ treat in children/adolescents)
- EARLY LOSS / PROLONGED RETENTION OF DECIDUOUS TEETH
- ECTOPIC TEETH
- Absent teeth, supernumeraries
- Impaction, delayed eruption
- Fraenum, local pathology
- Dental trauma
Describe the main local factors and anomalies that may present in the developing dentition
- Deciduous Teeth
– Early loss or prolonged retention of deciduous teeth - Permanent: number of teeth
–Absent teeth
–supernumeraries
–early loss (6s, 1s) - Permanent: position of teeth
–ectopic canines
–impaction of 1st molars, or premolars - Fraenum
what are the effects of early loss of upper E
impacted and crowded lower premolar
(E extracted due to caries)
6 drifting mesially and not leaving enough space for the 4 and 5 ie posterior crowding
Fitted in patient who has lost both lower Es-
(to prevent the 6 drifting forwards
Space maintainers ie lingual arch (fixed)
Early Loss of Deciduous Teeth
Effects depend on:
- Tooth lost
- Age
- Degree of Crowding in the Arch
Effects of early loss of deciduous teeth- tooth loss
–D, E space loss as 1st permanent molars drift mesially
(causes premolar crowding)
–C incisor midline shift as permanent incisors drift into
space
–A, B minimal effect
Effects of early loss of deciduous teeth- age
–Effects more severe with earlier loss
Effects of early loss of deciduous teeth- degree of crowding in the arch
–more space loss with D or E loss if crowding present
– greater midline shift with C loss if perm incisors crowded
Prolonged Retention of Deciduous
Teeth
(how common, which teeth and effects? what happens?)
- Relatively common
- Usually Es or Ds (radiograph re. successor)
- May delay permanent successor
- May become “submerged” or “infraoccluded” due to ankylosis
–tipping of adjacent teeth (first molars)
–almost all exfoliate naturally
–extract only if becoming completely submerged
Developmental Absence of
Permanent Teeth (“Hypodontia”)
how common and what other type of lack of teeth canyou have?
Relatively common (2-3%)
* Anodontia (complete absence)
what are the most common teeth missing? and what is severe hypodontia?
excluding 3rd molars:
upper laterals, then 2nd premolars, and lower central incisors
6 or more missing teeth (excluding 8s)
Tx of hypodontia?
- space closure
- Open or maintain space then bridgework / implants / denture
- accept (e.g. lower 5s)
Hypodontia: Upper Laterals
. how common
. associated with?
. Tx?
- Common (2-3%)
- Associated with ectopic canines and small
contralateral lateral incisors
*–space closure (crowding, Class II cases, 3s acceptable)
–bridgework (no crowding, 3s poor colour)
–usually need fixed appliances
Absent Second Premolars
- how common?
- can appear on Rx as late as?
- Tx?
- Prognosis?
- Common (2%)
- Can appear on radiographs as late as age 8 years
- – space closure (extract deciduous early)
– bridgework
– use space to treat crowding
– accept and retain Es
0 uncertain, unusual to last beyond age 30
Absent Lower Central Incisors- features?
treatment?
- Rare
- A`s usually retained
- Close space or bridgework
Supernumerary Teeth ($)
incidence? and location?
- Incidence 1-2%
- 80% are in the anterior maxilla
(* OPG - anterior occlusal)
Supernumary teeth classification?
- Morphology (Coniform and Tuberculate)
- Position (Mesiodens, Supplemental, Paramolar)
Supernumary teeth clinical effects?
- delayed eruption of teeth (e.g. Upper centrals)
- may erupt (mesiodens), crowding
- midline diastema (mesiodens)
Supernumerary Teeth: Treatment
- No treatment
- Extract
- Exposure and alignment of teeth with delayed eruption (Upper incisors)
- However, more than 70% of unerupted upper central incisors will erupt following removal of a supernumerary tooth
Impacted teeth
- First permanent molars
- Premolars
- Third molars
Impacted Teeth: Perm First Molars
incidence
location
prognosis?
3-4 percent
almost always in maxilla
2/3 will correct spontaneously, although unlikely to improve after 8 years
treatment of impacted permenant first molars?
- extraction of E
- Simple URA to disimpact
Impacted Teeth: Premolars
- what tooth and why
Usually 2nd premolars
Early loss of E
Tx of impacted premolars
- Extract 4 to allow eruption of 5
- Extract 7 and distalise 6 to create space
- Extract 5 (surgical)
- No treatment and review regularly
