Aetiology of Malocclusion II Flashcards
Definition of local causes of malocclusion
- A localised problem or abnormality within either arch, usually confined to 1,2 of several teeth producing a malocclusion
- Tends to get worse with time
List some local causes of malocclusion (5)
- Variation in tooth number
- Variation in tooth size or form
- Abnormalities of tooth position
- Local abnormalities of soft tissues
- Local pathology
What 4 ways can the aetiology of malocclusion be classified?
SKELETAL
- Class III
- High FMPA
DENTAL
- Missing teeth
SOFT TISSUE
- Lip trap
OTHER
- Habits
What does variation in tooth number include (5)
- Supernumerary teeth
- Hypodontia (developmentally absent teeth)
Variation of timing:
- Retained primary teeth
- Early loss of primary teeth
- Unscheduled loss of permanent teeth
In what arch are supernumerary teeth more common?
Anterior maxilla
In what gender are supernumerary teeth more common
Males
What are the 4 types of supernumerary teeth
- Conical
- May erupt - Tuberculate
- Tend not to erupt - Supplemental
- Often extracted - Odontome
What are mesiodens?
Supernumerary teeth that are close to midline
Do conicals affect eruption?
Tend not to prevent eruption, but may displace adjacent teeth
Do tuberculates affect eruption?
One of the main causes of failure of eruption of permanent upper incisors
What are supplemental teeth?
Extra teeth of normal morphology
- Most often upper laterals/lower incisors
- Often extract
Indications for extraction of supplementary teeth (3)
- If stopping eruption of permanent teeth
- Can cause crowding
- Causing central line shifts
What are the 2 types of odontome?
- Compound
- Discreet denticles - Complex
- Disorganised mass of dentine, pulp + enamel
Define hypodontia
Developmental absence of 1 or more teeth
- Mild/moderate/severe hypodontia
What teeth are normally affected by hypodontia?
Upper laterals
Second premolars
Do retained primary teeth affect eruption?
Yes
What malocclusions affect eruption?
- Tuberculates
2. Retained primary teeth
List some reasons why primary teeth do not exfoliate (remain retained) (5)
- Absent successor
- Ectopic successor/dilacerated
- Infra-occluded (ankylosed) primary molars
- Dentally delayed in terms of development
- Pathology
Tx for a retained primary tooth with an absent successor (2)
- Either maintain primary tooth as long as possible (if good prognosis) to keep space
OR
- Extract deciduous tooth early to encourage spontaneous space closure in crowded cases
EARLY ORTHO REFERRAL FOR ADVICE
Retained deciduous teeth:
Definition of infa-occluded primary molars
- Process where a tooth fails to achieve or maintain its occlusal relationship with adjacent teeth
- Causes temporary ankylosis
- Percussion sound
Grading system for infra-occluded primary molars (3)
- Slight
- Marginal ridge not level either side but above the contact point - Moderate
- Just at the contact point - Severe
- Lower deciduous molar falling well below the contact points
Management of a retained deciduous incisor - if the permanent successor is present (3)
> Usually self correct so keep under review
> Consider extraction if:
- Contact points are going subgingival
- Root formation of the successor is near completion
Management of a retained deciduous incisor - if permanent successor is absent (2)
Depends on potential of crowding:
- Retain if in good condition (onlay)
- Or extract and plan space management (ortho) or prosthetic tooth
List some causes for early loss of primary teeth (4)
- Trauma
- Periapical pathology
- Caries
- Resorption by successor
What can early loss of primary teeth lead to? (2)
- Crowding of adult teeth
2. Central line shifts
What does crowding depend on? (3)
- Which tooth is extracted
- When the tooth is extracted
- Patients inherent crowding
Define balancing extraction
Extracting a tooth from the opposite side of the same arch
Define compensating extraction
Extracting a tooth form the opposing arch of the same side
Do you have to balance/compensate primary incisors?
No
Very little impact
Do you have to balance/compensate primary canines? (2)
- Balancing extraction
- Can give centre-line shifts
Will get some mesial drift of buccal segments
Do you have to balance/compensate primary molars?
Space maintaining
As 6s drift mesially and steal 5s space
What teeth causes more space loss in molars
- With E’s > D’s
2. In upper> lower
List some factors that influence the impact on the loss of 6s (3)
- Age at loss
- Crowding
- Malocclusion
Ideal time for loss of lower 6
Ideally at the time of the bi-furcation development in 7s
What happens if loss of 6 after 7s have erupted?
Often poor space closure
What happens if loss of 6 too early?
Distal drift of 5’s
Protocol if U6 has to go
No compensation
Protocol if L6 has to go
Often compensation
When is balancing considered?
Not if spaced or well aligned
Consider if premolar crowding
Protocol for unscheduled loss of central incisor (2)
- Maintain space = reimplant
- Plan how to deal with space
- prosthesis
Examples of variation in tooth size/form
- Macrodontia
- Too large - Microdontia
- Too small - Abnormal form
Associated issues with macrodontia (3)
- Crowding
- Asymmetry
- Aesthetics
Associated issues with microdontia
- Leads to spacing
2. Linked to hypodontia
When should we check for a palpable buccal canine bulge?
From 9 years onwards
What does the clinical assessment for ectopic canines entail? (3)
- Visualisation/palpation
- Inclination of 2
- Mobility/colour of C or 2
- Mobility may indicate root resorption
3 P’s when looking at radiographs?
- Presence of teeth
- Position of teeth
- Pathology
What radiographs are needed for ectopic canine assessments? (2)
- OPT
- Anterior occlusal
Parallax technique
Management options for ectopic canines (3)
- Prevention
- Appropriate monitoring from 9 onwards
- Cinical assessment for symmetry - Extraction of C to encourage improvement in position of 3 (interceptive)
- Retain 3 and observe
Management for an ectopic first molar (3)
- Separator
- Attempt to distalise 6
- Extract E
Define transposition
Interchange in the positions of 2 teeth
Can be true/false
True transposition
Roots + crowns both switched too
False transposition
Crowns have switched but the root apices are in the correct place
Tx options for transposition (3)
- Accept
- Extract
- Correct
List some causes for local abnormalities of soft tissues (3)
- Digit sucking
- Frenum
- Tongue thrust
What can a labial frenum potentially cause?
Median diastema
List some examples of local pathology that can cause malocclusion (3)
- Caries
- Cysts
- Tumours
