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BDS3 Orthodontics > Aetiology of Malocclusion 2 - Local Causes of Malocclusion > Flashcards

Aetiology of Malocclusion 2 - Local Causes of Malocclusion Flashcards

1
Q

What is the prevalence of malocclusion in population?

A
  • 68% Malocclusion
  • 32% Normal occlusion
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2
Q

What are the local causes of malocclusion?

A
  • Variation in tooth number
  • Variation in tooth size or form
  • Abnormalities of tooth position
  • Local abnormalities of soft tissues
  • Local pathology
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3
Q

What is included in variation in tooth number for local cause of malocclusion?

A
  • Supernumerary teeth (extra)
  • Hypodontia (developmentally absent teeth)
  • Retained primary teeth
  • Early loss of primary teeth
  • Unscheduled loss of permanent teeth
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4
Q

What are supernumerary teeth and their prevalence?

A
  • Tooth or tooth-like entity which is additional to the normal series
  • Most commonly in anterior maxilla
  • males > females
    Prevalence:
  • 1% in primary dentition
  • 2% in permanent dentition
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5
Q

What are the types of supernumerary teeth?

A
  • Conical
  • Tuberculate
  • Supplemental
  • Odontome
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6
Q

What are conical supernumerary teeth?

A
  • Small peg shaped
  • Close to midline
  • May erupt (Extract)
  • Usually 1 or 2 in number
  • Tend to not prevent eruption but may displace adjacent teeth
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7
Q

What are tuberculate supernumerary teeth?

A
  • Tend not to erupt
  • Paired
  • Barrel-shaped
  • Usually extracted
  • One of the main causes of failure of eruption of permanent upper incisors
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8
Q

What are supplemental supernumerary teeth?

A
  • Extra teeth of normal morphology
  • Most often upper laterals or lower incisors
  • Can be third premolars, fourth molars
  • Often extract - decision based on form and position
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9
Q

What are the two types of odontome supernumerary teeth?

A

Compound - discreet denticles
Complex - disorganised mass of dentine, pulp and enamel

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10
Q

What is hypodontia and its prevalence?

A
  • Developmental absence of one or more teeth
  • Females > males 3:2
  • 4-6% population (excluding 8’s)
  • Commonly upper laterals (2s) > second premolars (5s)
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11
Q

What are retained primary teeth?

A
  • Disruption in sequence of eruption
  • A difference of more than 6 months between the shedding of contra-lateral teeth (Alarm bells)
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12
Q

Why are primary teeth retained?

A
  1. Absent successor
  2. Ectopic successor or dilacerated
  3. Infra-occluded (ankylosed) primary molars
  4. Dentally delayed in terms of development
  5. Pathology / supernumerary
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13
Q

What to do if there is an absent successor in primary teeth retention?

A
  • Either maintain primary tooth as long as possible
    (if good prognosis)
  • Or, extract deciduous tooth early to encourage
    spontaneous space closure in crowded cases
  • Early orthodontic referral for advice
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14
Q

What are infra-occluded primary molars?

A
  • Process where tooth fails to achieve or maintain its occlusal relationship with adjacent teeth
  • AKA submerged
  • Temporary ankylosis
  • Common 1-9%
  • Gives percussion sound
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15
Q

What are the 3 severity levels of infra-occluded primary molars?

A

Slight - Between occlusal surface and interproximal contact, less than 2mm

Moderate - Within occluso-gingival margins of interproximal contact

Sever - Below interproximal contact point

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16
Q

What can cause early loss of primary teeth?

A
  1. Trauma
  2. Periapical pathology
  3. Caries
  4. Resorption by successor
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17
Q

What does early loss of primary teeth depend on?

A
  • Which tooth is extracted
  • When tooth is extracted
  • Patient’s inherent crowding

Lead to localisation of crowding

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18
Q

What is balancing extraction?

A
  • Extraction of tooth from opposite side of same arch
  • Designed to minimise midline shift
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19
Q

What is compensating extraction?

A
  • Extraction of tooth from opposing arch on same side
  • Designed to maintain occlusal relationhip
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20
Q

How does early loss of incisors impact the dentition and treatment?

A
  • Very little impact
  • No compensating or balancing extraction
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21
Q

How does early loss of canines impact dentition and treatment?

A
  • Unilateral loss in crowded arch, can give centre-line shift
  • Will get some mesial drift of buccal segments
  • Consider balancing extraction
22
Q

How does early loss of molars impact dentition and treatment?

A
  • More space loss with E’s > D’s
  • More space loss in upper > lower
  • 6’s drift mesially and steal 5 space
23
Q

How does extraction timing of primary teeth affect dentition?

A
  • Most effect when primary teeth extracted early
  • Little effect if extracted late
24
Q

How does inherent crowding affect early loss of primary teeth?

A
  • Marker space loss in crowded patients
  • Minimal or no space loss in spaced dentitions
25
Q

When should you assess 6’s prognosis?

A
  • Routine assessment of 6’s prognosis dental age 8-9 years.
26
Q

What factors influence impact of the loss of 6s?

A
  • Age at loss
  • Crowding
  • Malocclusion
27
Q

How does age at loss of 6s affect dentition?

A

Upper arch - less important
Lower arch - If 7s erupted (late) often poor space closure, If too early distal drift of 5s particularly if Es lost at same time as 6s

28
Q

How does crowding affect dentition with loss of 6s?

A

Upper arch - potential for rapid space loss
Lower arch
- If spaced then will have spaces
- If aligned then will have spaces
- If crowded then best results likely

29
Q

How does timing effect dentition with unscheduled loss of central incisors?

A
  • Early loss will result in drift of adjacent teeth
  • Late loss will result in long term space
30
Q

What to do with unscheduled loss of central incisors?

A
  • Ideally maintain space by re implant or simple denture
  • Plan how to deal with space longer term i.e definitive prosthesis
  • If lateral incisor drifts to fill space then build up lateral or re-open space for prothesis
31
Q

What are the different variations in tooth size or form?

A

Too large - macrodontia
Too small - microdontia
Abnormal form

32
Q

What is macrodontia?

A
  • Tooth/teeth larger than average
  • Can be localised or generalised
    Problems
  • Crowding
  • Asymmetry
  • Aesthetics
33
Q

What is microdontia?

A
  • Tooth/teeth smaller than average
  • Can be localised or generalised
  • Leads to spacing
  • Linked to hypodontia
34
Q

What are abnormal forms of teeth?

A
  1. Peg shaped laterals
  2. Dens in dente
  3. Geminated/fused teeth
  4. Talon cusps
  5. Dilaceration
  6. Accessory cusps and ridges
35
Q

What are most common ectopic teeth?

A
  • Can be any tooth but most commonly
  • Third molars (8s)
  • Upper canines (3s)
  • First permanent molars (6s)
  • Upper centrals (1s)
36
Q

What are transpositions?

A
  • Unique and severe condition of ectopic eruption
  • Defined as interchange in position of two permanent adjacent teeth located at same quadrant in dental arch
37
Q

What is the prevalence of ectopic maxillary canines?

A
  • 1-3% population
  • 80% palatal

Check for palpable buccal canine bulge from 9years onwards
- Further investigation or refer if in doubt

38
Q

What is included in clinical assessment of ectopic canines?

A
  • Visualisation/palpation of any obvious bumps of 3
  • Inclination of 2
  • Mobility of c or 2
  • Colour of c or 2
39
Q

What is included in radiographic assessment of ectopic canines?

A
  • 2 radiographs needed to localise position
    (usually OPT and upper anterior oblique occlusal)
  • Use parallax technique
    3 Ps = Presence, Position, Pathology
40
Q

What are the management options for ectopic canines?

A

1.Prevention
2. Extraction c to encourage improvement in position of 3 (interceptive)
3. Retain 3 and observe (accept its position)
4. Surgical exposure and orthodontic alignment
5. (Surgical) Extraction
6. Autotransplantion

41
Q

What is included for prevention of ectopic canines?

A
  • Appropriate monitoring from age 9 onwards.
  • Clinical assessment
  • Symmetry
42
Q

What are ectopic first molars a sign of?

A
  • Crowding (greater in CLP)
  • Mesial path of eruption
  • Abnormal morphology of E
43
Q

How to manage ectopic first molars?

A
  • Separator
  • Attempt distalise 6
  • Extract E
44
Q

Prevalence of ectopic first molars?

A
  • Less than 5%
  • More commonly U arch
  • Reversible before age 8
  • Caries risk
45
Q

What are potential causes of ectopic upper central incisors?

A
  • No obvious cause
  • Supernumerary (Tuberculate or odontome)

Trauma to primary predecessor
- Ankylosis of primary tooth
- Displacement of tooth germ
- Dilaceration of root

46
Q

What is the classification of Transpositions?

A
  • True/ Pseudo
    Most common
  • Upper canines and first premolar
  • Lower canines and incisors
47
Q

Treatment options for transposition?

A
  • Accept
  • Extract
  • Correct
48
Q

What are some local abnormalities of soft tissues?

A
  • Digit sucking
  • Fraenum
  • Tongue thrust
49
Q

What can non-nutritional digit sucking habit cause?

A
  1. Proclined UI
  2. Retroclined LI
  3. Anterior open bite
  4. Unilateral posterior crossbite
    - Due to narrow maxillary arch
    - May cause mandibular displacement
50
Q

What local abnormality can the labial fraenum cause?

A
  • May cause median diastema
51
Q

What are the three forms of local pathology?

A
  • Caries
  • Cysts
  • Tumours
52
Q

Definition of ectopic tooth?

A
  • Tooth that is not located in dental arch due to faulty course during eruption

BDS3 Orthodontics (10 decks)

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