Aetiology of Malocclusion II Flashcards
What is the prevalence of malocclusion in the population and what are its main etiological categories?
Prevalence is 68% malocclusion vs 32% normal occlusion. Main categories are:
- Skeletal (e.g., Class III, high FMPA)
- Dental (e.g., missing teeth)
- Soft tissue (e.g., lip trap)
Define a local cause of malocclusion and state its key characteristics.
A local cause of malocclusion is:
- A localized problem/abnormality within either arch
- Usually confined to one, two, or several teeth
- Tends to get worse with time
- Has scope for interceptive treatment
- Important to recognize early
Compare and contrast the prevalence and characteristics of supernumerary teeth in primary vs permanent dentition.
Supernumerary teeth:
Primary dentition: 1% prevalence
Permanent dentition: 2% prevalence
More common in males
Most commonly found in anterior maxilla
Detail the four types of supernumerary teeth and their specific characteristics.
Conical:
Small, peg-shaped
Close to midline (mesiodens)
May erupt
Usually 1-2 in number
Can displace adjacent teeth but usually don’t prevent eruption
Tuberculate:
Tend not to erupt
Paired
Barrel-shaped
Usually require extraction
Major cause of permanent upper incisor eruption failure
Supplemental:
Normal morphology
Common in upper laterals or lower incisors
Can be third premolars or fourth molars
Extraction decision based on form & position
Odontome:
Compound type: discrete denticles
Complex type: disorganized mass of dentine, pulp, and enamel
What are the key characteristics of hypodontia and its demographic distribution?
Developmental absence of one or more teeth
Female:Male ratio = 3:2
4-6% population prevalence (excluding wisdom teeth)
Most commonly affects upper lateral incisors followed by second premolars
List and explain the five main causes of retained primary teeth.
- Absent successor
- Ectopic successor or dilacerated tooth
- Infra-occluded (ankylosed) primary molars
- Dental developmental delay
- Pathology/supernumerary presence
What are the characteristics and management options for infra-occluded primary molars?
also called submerged
Defined as failure to achieve/maintain occlusal relationship with adjacent teeth
Represents temporary ankylosis
Prevalence: 1-9%
Diagnostic feature: distinctive percussion sound
Management depends on severity and age of patient
Define and differentiate between balancing and compensating extractions.
Balancing extraction:
Extraction of tooth from opposite side of same arch
Purpose: minimize midline shift
Compensating extraction:
Extraction of tooth from opposing arch of same side
Purpose: maintain occlusal relationship
How does the impact of early primary tooth loss vary by tooth type and timing?
Incisors:
Very little impact
No compensating or balancing extraction needed
Canines:
Unilateral loss in crowded arch can cause centerline shift
Some mesial drift of buccal segments
Consider balancing extraction
Molars:
More space loss with second primary molars vs first primary molars
Greater space loss in upper vs lower arch
First permanent molars drift mesially and compromise second premolar space
Impact greatest with early extraction
More severe in crowded patients
What are factors that influence the impact of the loss of the 6s?
- age at loss
- crowding
- malocclusion
What is the optimal age for routine assessment of first permanent molar prognosis and why is timing crucial?
Optimal age: 8-9 years (dental age)
Crucial timing factors:
Root development of adjacent teeth
Eruption status of second permanent molars
Potential for spontaneous space closure
Growth potential remaining
Compare and contrast the impact of first permanent molar loss between upper and lower arches.
what happens if too early
Upper arch:
Generally less critical
Better potential for spontaneous space closure
More favorable movement of second molars
Lower arch:
More problematic
If L7s (second molars) already erupted:
Often results in poor space closure
Risk of tipping
If too early:
Risk of distal drift of second premolars
Particularly problematic if Es (second primary molars) lost simultaneously
How does the presence of crowding affect the prognosis of first permanent molar loss?
upper vs lower
Upper arch:
Potential for rapid space loss in all cases
Lower arch outcomes vary by crowding status:
Spaced dentition: Will likely maintain spaces
Aligned dentition: Likely to develop spaces
Crowded dentition: Best prognosis for spontaneous space closure
What are the key timing considerations, consequences, and management options for unscheduled loss of a permanent central incisor?
and if lateral drifts to fill space
Timing Considerations:
Early loss leads to drift of adjacent teeth
Late loss typically results in long-term space maintenance
Immediate Management:
Space maintenance is typically required
Consider immediate reimplantation if available and appropriate
Long-term Management Options:
Space Maintenance + Definitive Prosthesis:
Simple interim denture initially
Plan for long-term space maintenance
Eventually definitive prosthetic replacement
Consider implant when growth complete
If Lateral Incisor Drifts to Fill Space:
Options include:
Re-opening space orthodontically for prosthetic replacement
Building up lateral incisor to simulate central
Key Considerations:
Patient age and growth status
Condition of adjacent teeth
Space available
Occlusal relationship
Aesthetic demands
Financial considerations
Long-term prognosis
What are the 3 variation in size or form?
- Too large - macrodontia
- Too small - microdontia
- Abnormal form
Characteristics of macrodontia
problems
tooth/teeth larger than average
localised or generalised
problems:
crowding
asymmetry
aesthetics
Characteristics of microdontia
tooth/teeth smaller than average
localised or generalised
leads to spacing
linked to hypodontia
Types of abnormal form
- Peg shaped laterals
- dens in dente
- geminated/fused teeth
- talon cusps
- dilaceration
- accessory cusps
and ridges
What are the most common ectopic teeth?
third molars (8s)
upper canines (3s)
first permanent molars (6s)
upper centrals (1s)
Detail the clinical assessment protocol for ectopic maxillary canines.
- Visualization/palpation of any obvious canine bumps
- Assessment of lateral incisor inclination
- Checking mobility of primary canine or lateral incisor
- Color assessment of primary canine or lateral incisor
- Key timing: Should check for palpable buccal canine bulge from age 9 onwards
What radiographs are required to assess ectopic canines?
3 p’s
2 radiographs needed to localise position - usually OPT & upper anterior oblique occlusal
Parallax technique
3 Ps= presence, position, pathology
What are the management options for ectopic canines and their indications?
- Prevention (appropriate monitoring from age 9)
- Interceptive extraction of primary canine
- Retention and observation of permanent canine
- Surgical exposure and orthodontic alignment
- Surgical extraction
- Autotransplantation
Canine position (80% palatal)
Associated conditions (higher risk with absent/peg-shaped laterals, Class II div 2)
Patient age and cooperation
Crowding status
Describe the characteristics and management of ectopic first permanent molars (6s).
Characteristics:
Affects less than 5% of population
More common in upper arch
Reversible before age 8
Increased caries risk
Often indicates:
Crowding (higher in cleft lip/palate)
Mesial path of eruption
Possible abnormal morphology of E (second primary molar)
Management options:
Separator placement
Attempt to distalize 6
Extract E (second primary molar)
What are the possible causes and diagnostic considerations for ectopic upper central incisors?
Possible causes:
Idiopathic (no obvious cause)
Supernumerary teeth:
- Particularly tuberculate type
- Odontome
Trauma to primary predecessor
- Ankylosis of primary tooth
- Displacement of tooth germ
- Dilaceration of root
Diagnostic considerations:
Check for sequence
Assess symmetry
Radiographic investigation
History of trauma
What is the definition, class, and treatment options of tooth position abnormalities?
what teeth are most common
Definition: interchange in the position of two teeth
Classification: True / Pseudo
Most commonly
upper canines & first premolar
lower canines & incisors
Treatment options:
1) accept 2) extract 3) (correct)
What are the four characteristic features of a digit-sucking habit’s effect on dentition?
- Proclined upper incisors
- Retroclined lower incisors
- Anterior open bite
- Unilateral posterior crossbite due to:
Narrow maxillary arch
Potential mandibular displacement
What are the 3 local abnormalities of soft tissues?
- digit sucking
- fraenum
- tongue thrust
What can abnormality of the labial fraenum cause?
median diastema
What are the three main categories of local pathology that can cause malocclusion, and how do they affect treatment planning?
Caries:
Can lead to early tooth loss
Space loss
Altered eruption paths
Modified treatment timing
Cysts:
Can displace teeth
May require surgical intervention
Affects timing of orthodontic treatment
May compromise bone support
Tumors:
Can cause tooth displacement
May affect growth
Requires coordination with other specialists
May modify treatment objectives
