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BDS3 Orthodontics > local causes of malocclusion > Flashcards

local causes of malocclusion Flashcards

1
Q

prevalence of malocclusion

A

68% malocclusion

32% noraml occlusion

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1
Q

4 categories of causes of malocclusion

A
  • skeletal
    • class III
    • high FMPA
  • dental
    • missing teeth
  • soft tissue
    • lip trap
  • other
    • habits
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2
Q

local causes of malocclusion

A

a localised problem or abnormality within either arch, usually confined to one, two or several teeth producing a malocclusion

  • Tend to get worse with time
  • Scope for interceptive treatment
    • Good to recognise
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3
Q

categories of local causes of maloccusion (5)

A
  • Variation in tooth number
  • Variation in tooth size or form
  • Abnormalities of tooth position
  • Local abnormalities of soft tissue
  • Local pathology
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4
Q

5 causes of variation in toothnumber

A
  1. Supernumerary teeth (extra)
  2. Hypodontia (developmentally absent teeth)
  3. Early loss of primary teeth
  4. Retained primary teeth
  5. Unscheduled loss of permanent teeth

3-5 are variations in timing of teeth present

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5
Q

supernumarary teeth

A

a tooth or tooth a tooth or tooth-like entity 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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6
Q

4 types of supernumarary teeth

A
  1. Conical
  2. Tuberculate
  3. Supplemental
  4. Odontome
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7
Q

conical supernumerary

A
  • Small, peg shaped
  • close to midline = mesiodens
  • may erupt (extract)
  • usually 1 or 2 in number
  • tend not to prevent eruption but
    • may displace adjacent teeth
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8
Q

tuberculate supernumaries

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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9
Q

supplemental supranumeraries

A
  • extra teeth of normal morphology
  • most often upper laterals or lower incisors
    • can be third premolars, fourth molars often extract
  • cause crowding, centre-line shift etc – impeding space of other teeth
  • often extract - decision based on form and position (keep better)

here 13, 12, 11,21, 22, extra 22, 23

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10
Q

odontome supernumeraries

types

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

here 21, 22, 63 with 23 above but in between mass of structure impeding eruption and displaced 24

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11
Q

odontome management

A

refer to orthodontics and oral surgery – investigate, remove obstruction to allow further eruption of permanent teeth

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12
Q

whats odd here

A

Lower incisors present

12, 51, 61, 22

  • Sequence of eruption is incorrect -> investigate

Radiographs – can see 51 and 61 with 11 and 21 above but in between there’s other opacities = supernumerary teeth

  • (refer to oral surgery – remove obstructions allowing incisors to erupt)
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13
Q

hypodontia

A
  • developmentally absence of one or more teeth
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14
Q

occurence of hypodontia

A
  • Females > males 3:2
  • 4-6% population (excluding 8’s)
  • commonly upper laterals (2s) > second premolars (5s)
  • mild, moderate and severe depending on how many teeth are missing
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15
Q

retained primary teeth

malocclusion cause

A
  • A disruption in the sequence of eruption

A difference of difference of more than 6 months between the shedding of contra shedding of contra-lateral lateral teeth.

  • Alarm bells
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16
Q

5 reasons primary teeth may be retained

A
  • Absent successor
    • nothing to resorb primary tooth out due to hypodontia of permanent
  • Ectopic successor or dilacerated /impacted
  • Infra-occluded (ankylosed) primary molars
  • Dentally delayed in terms of development
  • Pathology/supernumerary
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17
Q

how to deal with retained primary tooth when absent successor

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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18
Q

how to deal with retained primary canine here

A
  • clinical and radiographic investigations to see what is happening to permanent canine
  • On periapical can see 13 is present and it is nearly in line but the deciduous canine is impeding its eruption into its proper place
    • Need deciduous extracted (interceptive extraction) allow spontaneous eruption of permanent canine
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19
Q

infra-occluded primary molars falsely referred to as

A

submerged molars

incorrect

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20
Q

infra-occluded primary molars

A

process where a tooth fails to achieve or maintain its occlusal relationship with adjacent teeth

  • temporary ankylosis
  • Common 1-9%*

Different percussion sound

Look like they are sinking because they stay where they are and the rest of the teeth around them continue to develop and grow – everything moving around it whilst it stays still

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21
Q

grades for infraoccluded primary molars

A

Slight

  • between occlusal surface and interproximal contact - less than 2mm

Moderate

  • within occluso-gingival margins of interproximal contact

Severe

  • below interproximal contact point

Moderate and severe – refer to specialist and consider extraction of deciduous infra-occluded tooth/teeth

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22
Q

management of infra-occluded primary molars

A
  • permanent successor present
    • Usually self-correct so keep under review.
    • Consider extraction if:
      1. contact points are going subgingival
      2. root formation of the successor is near completion
  • permanent successor absent
    • Depends on potential of crowding:
      • Retain if in good condition (onlay)
      • Or extract and plan space management (orthodontics)
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23
Q

4 reasond for early loss of primary teeth

A
  • Trauma
  • Periapical pathology
  • Caries
  • Resorption by successor
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24
Q

localisation of crowding

depends on

A
  • Which tooth is extracted
  • When the tooth is extracted
  • Patient’s inherent crowding
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25
Q

balancing extraction

A
  • By extraction of a tooth from the opposite side of the same arch
  • Designed to minimise midline shift.
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26
Q

compensating extraction

A
  • By extraction of a tooth from the opposing arch of the same side
  • Designed to minimise maintain occlusal relationship
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27
Q

which primary teeth tend to be lost early

A

Incisors

  • Very little impact
  • No compensating or balancing ext

Canines

  • unilateral loss in crowded arch, can give centre-line shift
  • will get some mesial drift of buccal segments
  • consider balancing extraction
    • e.g. lose upper right, extract upper left to keep centre-line

molars

  • more space loss with E’s > D’s
  • more space loss in upper > lower
  • 6’s drift mesially and steal 5 space
    • Impede 5 eruption
  • Look to space maintain tend not to balance or compensate

Get second opionion if unsure

28
Q

when to do extractions

A
  • most effect when primary teeth extracted early
  • little effect if extracted late
29
Q

inherent crowding

A
  • marked space loss in crowded patients
  • minimal or no space loss in spaced dentition
30
Q

uscheduled loss of 6s

A
  • Routine assessment of 6’s prognosis dental age 8-9 years
  • Seldom ideal tooth of choice for relief of crowding
  • But planned loss at correct age is better than later enforced loss
31
Q

3 factors that inflluence the impact on the loss of 6s

A
  • Age at loss
  • Crowding
  • Malocclusion – class II or III
32
Q

age of loss of 6s

A
  • Upper arch: Less important
    • 7s will erupt in 6s position
  • Lower arch: ideally at the time of bi-furcation development in 7s
    • If L7s erupted (late) - Often poor space closure
    • If too early – space - Distal drift of 5’s
33
Q

crowding in upper arch

and 6 removal

A

potential for rapid space loss

34
Q

crowding in lower arch

and 6 removal

A

spaced -> will have spaces

aligned -> will have spaces

crowded -> best results likely

35
Q

2 fundamentals of 6s removal

A

compensation

balancing

36
Q

compensation

6s extraction

A
  • If U6 has to go NO compensation
  • If L6 has to go then OFTEN compensation
    • Get specialist opinion
37
Q

balancing

6s extraction

A
  • Not if spaced or well aligned
  • Consider if premolar crowding
38
Q

malocclsuion - class II or III

impact on 6s extraction

A

Class II upper molars are more important – can use space to relieve crowding or reduce overjet

Whereas in class III – lower molars are more important

39
Q

unscheduled loss of central incisor

A
  • In first instance maintain space = re implant
    • Plan how to deal with space - Prosthesis?

Can get centre-line shifts and space loss which makes it harder for the orthodontist to create space and symmetry

40
Q

3 variations in tooth size or form

A
  1. Too large – macrodontia
  2. Too small – microdontia
  3. Abnormal form
41
Q

macrodontia

A
  • tooth/teeth larger than average
  • localised or generalised problems
    • crowding
    • asymmetry
    • aesthetics

dealt with by restorative team and orthodontist

42
Q

microdontia

A
  • tooth/teeth smaller than average
  • localised or generalised
  • leads to spacing
  • linked to hypodontia
43
Q

6 types of abnormal tooth form

A
  1. Peg shaped laterals (diminutive)
  2. dens in dente
  3. geminated/fused teeth
  4. talon cusps
  5. dilaceration
  6. accessory cusps and ridge
44
Q

abnormalities in tooth position

A
  • ectopic
  • transpositions
45
Q

ectopic teeth tend to be

A
  • can be any tooth but most commonly
    • third molars (8s)
    • upper canines (3s)
    • first permanent molars (6s)
    • upper centrals (1s)
46
Q

ectopic canines occurance

A
  • 1-3% of population
  • 80% palatal
  • associated with small or absent upper laterals

check for palpable buccal canine bulge from 9 years onwards

  • Further investigation or refer if in doubt
47
Q

4 parts of clinical assessment of ectopic canines

A
  1. Visualisation/palpation of any obvious bumps of 3
  2. Inclination of 2
  3. Mobility of c or 2 root resorption
  4. Colour of c or 2 loss of vitality due to root resorption
48
Q

radiographic assessment of ectopic canines

A
  • 2 radiographs needed to localise position
    • usually OPT & anterior occlusal - vertical parallax
      • 2 periapicals - horizontal parallax
      • More accurate but likely already have OPT – also a larger view to assess any pathology

Parallax technique

  • 3 Ps= presence, position, pathology
49
Q

3Ps to look for in radiograph

A

Presence

Position (parallax technique)

Pathology

50
Q

6 management strategies of ectopic canines

A
  1. Prevention
  2. Extraction c to encourage improvement in position of 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
51
Q

prevention of ectopic canines

A
  • Appropriate monitoring from age 9 onwards.
  • Clinical assessment
    • Symmetry
52
Q

issue of ectopic canine here

A

can see ectopic canine has taken away some of the lateral incisor roots

53
Q

surgical exposure and orthodonic allignement of ectopic canine

A
  • 63 present in the top picture*
  • Bottom left can see 2 permanent canines area palatal to their deciduous teeth (53 and 63 present)*
  • Surgically – not erupt expose them – if erupted leave them,*
  • xtract deciduous canines, f*
  • ixed appliance pull the permanent canine into their correct positions (bottom right)*
54
Q

ectopic first molars (6s)

A

Less than 5%

  • More commonly upper arch

Reversible before age 8

If left and not monitored Caries risk – plaque/food trap

55
Q

ectopic first molars are sign of (2)

A

Sign of

  • crowding
  • mesial path of eruption
56
Q

management of ectopic first molar (3)

A
  • . Separator
  • Between distal E and mesial 6
  • Attempt distalize 6
    • Orthodontically fix appliance
    • Up righting it and allowing eruption
  • extract
57
Q

checks for ectopic upper central incisors

A

sequence

symmetry

58
Q

why ectopic upper central incisors

A

supernumarary

dilacerated (trauma)

59
Q

possible treatment for ectopic upper central incisors

A
  • Surgical exposure
    • removal of supernumerary emoval of supernumerary if present + Bond gold chain
  • Make space
    • above 9 yrs
      • orthodonic traction
      • bonded retainer

*

60
Q

issue in this radiograph

A
  • 11 erupted, 21 not and 22 is erupting*
  • Sequence wrong - investigate
  • 61 is dark grey in colour*
  • trauma?
  • See permanent incisor above the 61*
  • present and no obstructions or supernumeraries
  • But the angle of 21 is not correct*
  • due to dilaceration
    • root correct way,
    • bend in root so crown is pointing in wrong direction

Need surgical and orthodontic treatment to correct

61
Q

transpositions

A

Interchange in the position of two teeth

  • Classification
    • True (root and crown)
    • Pseudo (just crown, root apices still correct location)
  • Most commonly
    • upper canines & first premolar
    • lower canines & incisors
62
Q

3 treatment options for transpositions

A
  1. accept
  2. extract – close space
  3. (correct) – only in mild pseudo transposition
63
Q

3 local abnoralities of soft tissue

A
  1. digit sucking
  2. frenum
  3. tongue thrust
64
Q

non-nutritional (digit) sucking

4 consequences on occlusion

A
  1. proclined UI
  2. retroclined LI
  3. anterior open bite
  4. unilateral posterior crossbite
  • Thumb sucking causes negative pressure in the mouth*
  • Prevents further transverse growth of maxilla – unilateral posterior crossbite
  • Pushes upper incisors forwards – proclined*
  • Lower incisors pushed into mouth – retroclined*
  • Create gap - AOB*
65
Q

labial frenum

A

may causes median diastema

Retract the lip and slightly pull on the frenum see blanching of interdental area between papilla and upper incisors

  • Leave until permanent canines erupted into positions – can cause spontaneous closure of diastema as the frenum regresses
    • If persists and more than 3mm and concern to pt – can do frenectomy and orthodontically close space (need permanent bonded retainer for life)
66
Q

tongue thrust

A

Pt put tongue between upper and lower teeth out the mouth

  • Can cause
    • AOB
    • Splaying of teeth
    • Spacing
67
Q

reasons for tongue thrust

A
  • Endogenous – medical issues (Downs); macroglossia
  • Exogenous – habit (need to stop habit before tx to prevent relapse)
68
Q

3 local pathology causes of malocclusion

A
  1. caries
  2. cysts
  3. tumours

BDS3 Orthodontics (13 decks)

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