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Ortho > Delayed eruption of maxillary canine > Flashcards

Delayed eruption of maxillary canine Flashcards

1
Q

When does development of the upper and lower canines begin? When is crown calcification complete?

A

Age 4-5 months

Crown calcified at 6-7 years

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2
Q

Describe the position of the canines when they are developing

A

High up in the maxilla

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3
Q

Describe the path of eruption of the maxillary canines?

A
  • Migrate forwards and downwards to lie buccal and mesial to the apex of the C before erupting down the distal aspect of the root of the lateral incisor
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4
Q

How long is the path of eruption of upper canines?

A

22mm - this is the longest of all the teeth

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5
Q

What is the normal eruption time of upper and lower canines?

A

Upper - 11-12

Lower 10-11

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6
Q

What is the frequency of congenitally missing canines? What is the significance?

A

0.3% for upper and 0.1% for lower (Caucasians)

This means that delayed eruption is almost always due to impaction rather than it being missing

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7
Q

What is the frequency of impacted upper canines?

A

1-2%

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8
Q

What % of upper canine impaction is bilateral?

A

8% bilateral

92% unilateral

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9
Q

What position are unerupted canines more likely to be in?

A

Twice as likely to be palatally impacted

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10
Q

Where can the canines be displaced?

A
  • Buccally
  • Palatally
  • (sometimes horizontally above the apices of teeth or adjacent to the nose)
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11
Q

Describe the proposed aetiology of ectopic canines

A

Polygenic and mulifactorial

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12
Q

What is the most likely aetiology for buccally displaced canines?

A

Crowding - as the canine is the last tooth in sequence to erupt, therefore crowding can manifest as a lack of space for the canine

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13
Q

What study found the relationship of crowding with buccal and palatal canines, and what were the %?

A

Jacoby found 85% of buccally displaced canines were associated with crowding but 83% of palatal canines had enough space (therefore only buccal associated with crowding)

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14
Q

List the possible causes of palatally impacted canines

A
  • Long and tortuous path of eruption
  • Short root, peg shaped or congenitally absent upper lateral incisor (guidance theory)
  • Genetics (genetic theory)
  • Other local pathology
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15
Q

Describe the guidance theory

A

The canine uses the distal aspect of the lateral incisor to guide into position, therefore when it is small, or absent, there is no guidance

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16
Q

What is the evidence for the guidance theory?

A

Becker found pts with absent or short rooted upper laterals were 2.4x more likely to have palatally displaced canines

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17
Q

Describe the theory of genetics in canine ectopia

A

Familial tendency
Females > males
Greater prevalence in europeans
Occurs in association with other dental anomalies which are also inherited e.g. hypodontia of laterals

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18
Q

List other abnormalities that are associated with palatally displaced canines

A
  • Cleft lip and palate (usually due to affected lateral)
  • Class 2 div 2 (possibly due to altered position of laterals)
  • Other less important = displaced crypt, transposition, ectopic position of other teeth etc
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19
Q

Why is early monitoring of the position of canines in children important?

A

To allow early detection for early interceptive treatment, as this is a cost-effective and simple management for ectopic canines

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20
Q

When should you start palpating to assess the position of canines in children

A

Once a year from the age of 8 onwards

record it in the notes

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21
Q

Scenario: you cannot feel a bulge in a child aged 8 or 9, is this worrying?

A
  • No - it only becomes abnormal if you cannot palpate from age 10 onwards
  • We only start palpating at 8 as good practice
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22
Q

List the steps of clinically assessing the position of the canines

A
  • Check stage of development compared to age of child
  • Full ortho assessment and the angulation of lateral incisors
  • If Cs present - check for mobility
  • Visually inspect for a bulge
  • Palpate for the canines
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23
Q

What do you ask the patient if they have unilateral impaction?

A

Ask when the canine erupted (if >6 months then it is worrying)

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24
Q

Where is the normal position for the canine bulge?

A

In the buccal sulcus slightly distal to the upper lateral incisor root

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25
Q

What do you do on palpation if there is bilateral impaction?

A

You compare both sides to each other (are they the same position)

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26
Q

What does the inclination of the lateral incisor tell us about the position of the canine?

A
  • Distal angulation = palatal impaction

- Mesial angulation = buccal impaction

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27
Q

When should you consider radiographic examination for the position of canines

A

After the ages 10-11 (before this provides little benefit, therefore it will not be justified)

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28
Q

What do we look for in radiographs of an unerupted canines?

A
  • Location and position of the crown and the root apex relative to adjacent teeth and the arch
  • Prognosis of the adjacent teeth and C if present
  • Presence and degree of resorption of the incisors
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29
Q

What are the advantages of taking a DPT for unerupted canines?

A
  • You can see the position and presence of all the permanent teeth
  • You can position the canine in terms of angulation, overlap, height and position of apex
  • You can assess poor prognosis teeth
  • You can assess resorption of the incisors and C if present, cystic changes or other pathologies
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30
Q

What is the disadvantage of a DPT for localisation of canines?

A

It often suggests the canine is further away from the midline that it actually is, therefore must be supplemented with an intraoral view

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31
Q

Describe the use of periapicals for assessment of ectopic canines

A
  • Assess prognosis of the retained C and degree of resorption
  • Parallax
32
Q

Advantages of an upper standard occlusal in the assessment of canine position

A
  • Good view of upper anterior teeth and the C for assessment of resorption
  • You can assess the proximity of the canines to the roots of the incisors
  • Parallax
33
Q

When is CBCT used for localisation of canines?

A
  • When they cannot be accurately located with other techniques (parallax)
  • When you suspect root resorption
  • Suspected cystic changes or other pathology
  • Marked displacement requiring surgical removal
34
Q

Why is CBCT not routinely used for localisation of canines?

A

It has a high effective dose compared to conventional radiographs

35
Q

What is parallax

A

A technique used to determine the position of an unerupted tooth relative to the neighbouring tooth using two radiographs taken at different angles (horizontally or vertically)

36
Q

What is the parallax rule

A

SLOB - same lingual (palatal), opposite buccal

- If no change = in line with the arch

37
Q

Which films are used in horizontal parallax?

A
  • Two PAs at different angles

- USO and PA (or upper lateral occlusal)

38
Q

Which films are used for vertical parallax?

A
  • PA and USO
  • DPT and USO
  • DPT and PA
39
Q

What type of parallax is diagnostically more sensitive?

A

Horizontal

40
Q

What do you look for in vertical parallax?

A

How the position of the unerupted tooth changes with respect to the incisor roots

41
Q

Why are buccal canines more likely to erupt?

A

The buccal bone and mucosa is much thinner than it is palatally

42
Q

How to manage buccally displaced canines

A
  • Relief of crowding prior to eruption (may result in spontaneous improvement)
  • Extraction if aesthetic 2-4 contact
  • If it does not erupt - surgical exposure with gold change or SS ligature + traction
43
Q

What are the tx options for palatally displaced canines

A
  • Early interceptive
  • Surgical exposure and orthodontic alignment
  • Transposition
  • Surgical extraction
  • Leave and monitor
44
Q

Describe early interceptive tx of palatal canines

A
  • Extraction of retained deciduous canine +/- space maintainer, as an attempt to spontaneously improve the position of the canine
45
Q

Indications for early interceptive tx of palatal canines

A
  • Young pt (10-13)
  • Limited or absence of crowding is ideal (or you can use a space maintainer)
  • Need space in the arch
  • Good position for eruption
46
Q

How long do you wait for the canine to spontaneously improve after interceptive tx?

A

12 months

If it hasn’t erupted by then, other tx options are considered

47
Q

Indications for surgical exposure and alignment of canines

A
  • Young and motivated pt
  • Healthy dentition
  • Favourable canine position that is within the reach of orthodontics
  • Space available (or can be created)
48
Q

Describe the sequence of tx for surgical exposure and alignment

A
  • Make space available (sometimes this is done after the canine has initially been exposed)
  • Day case GA to expose canine
  • Commence traction after 2 weeks
  • Once erupted - bond a bracket and attach to archwire (you can use a FA or removable)
49
Q

What do they do during surgical exposure of the palatal canine?

A
  • Raise palatal flap
  • Surgically uncover the tooth by removing bone
  • Dry, etch and bond attachment
  • Apply gold chain to the bonded attachment and ligature in the buccal sulcus
  • Replace flap
50
Q

What are the advantages of surgical exposure and ortho alignment of palatally ectopic canines?

A
  • Tooth remains vital (due to slow movement)

- The right tooth is in the right place - optimal aesthetics and function

51
Q

What are the disadvantages of surgical exposure and ortho alignment of palatally ectopic canines?

A
  • Requires GA and surgical procedure

- Requires long tx - 2-2.5 years

52
Q

When is canine transplantation timed for optimal tx?

A

When the root is 2/3 - 3/4 its final length

- However usually it is beyond this when it is diagnosed as ectopic

53
Q

When is canine transplantation indicated?

A
  • It is possible to remove the canine in one piece, without damaging any adjacent teeth/structure
  • There is space to accomodate the canine in the arch and occlusion
  • There is sufficient alveolar bone to accept the tooth
  • The patient does not want lengthy treatment
54
Q

Describe the process of canine transplantation

A
  • Day case GA
  • Canine removed (palatal flap and removal of bone)
  • Surgical socket created and canine placed inside
  • Flexible splint for 6 weeks
55
Q

What are the common causes of failure of canine transplantation

A 
Replacement resorption (ankylosis) 
Inflammatory resorption
56
Q

What is replacement resorption?

A

The root surface is damaged during the procedure + use of a rigid splint encourages healing via bone rather than fibrous union

57
Q

What is inflammatory resorption

A

Death of pulpal tissue

58
Q

How is failure of canine transplantation reduced?

A
  • Meticulous atraumatic surgical technique

- Stabilisation with a sectional archwire for 6 weeks

59
Q

When is RCT indicated after canine transplantation?

A
  • If the tooth had closed apices - carried out 10 days after transplantation
60
Q

Advantages of canine transplantation

A
  • Quick (doesn’t need lengthy ortho)
61
Q

Disadvantages of canine transplantation

A
  • GA and surgery
  • May devitalise and require RCT
  • Risk of replacement and inflammatory resorption
  • Variable prognosis compared to ortho traction as it is surgeon and skill dependent
62
Q

What are the indications for surgical removal of an impacted canine?

A
  • Retained C is aesthetically acceptable and pt denies or does not want complex tx (required fully informed consent about limited lifespan)
  • Aesthetic 2-4 contact
  • Canine is severely displaced or in a position where it impedes ortho tx
  • Where there are pathological changes e.g. root resorption
  • Other options are not appropriate e.g. poor prognostic positioning
63
Q

What options are there to replace the canine with surgical exposure

A
  • If C present, retain and restore
  • If 2-4 contact - you can restore the 4 to look like a 3
  • Space closure with ortho
  • Bridge or implant
64
Q

What happens if a pt denies tx and wants to leave it where it is

A
  • Requires fully informed consent and good record keeping - refer to orthodontist so they can discuss the full risks of leaving the canine where it is (esp important for young patients)
65
Q

What are the indications for leaving in situ and monitoring an ectopic canine?

A
  • Pt denies tx after full discussion of risks
  • No evidence of root resorption of adjacent teeth or other pathology
  • Severely displaced canine away from dentition
66
Q

What factors affect tx options for ectopic canines

A
  • Pt expectations
  • Underlying malocclusion
  • Position of the canine
  • Presence of crowding or spacing
  • Condition of the retain c
  • Condition of the adjacent teeth
67
Q

List the sequale of ectopic canines

A
  • Root resorption **
  • Ankylosis
  • Coronal resorption
  • Space loss
  • Cystic changes
  • Restorative burden
68
Q

% of children aged 10-13 with resorption of permanent incisor roots

A

0.6-0.8%

69
Q

What is transposition

A

Interchange in position of two teeth, almost always involving the canine (and almost always maxillary)

70
Q

List the prognostic factors for correction of ectopic canines

A

Overlap (mesio-distal position)
Vertical height
Angulation
Position of the apex

71
Q

List the prognosis from good, average and poor for overlap of incisor

A

Good = no horizontal overlap
Average - up to half the root width
- Poor - complete overlap

72
Q

List the prognosis from good, average and poor for vertical height of the canines relative to the incisors

A
  • Good - canine positioned between CEJ- halfway up the root of the incisors
  • Average - canine positioned >half but
73
Q

List the prognosis from good, average and poor for angulation of the canines

A 
Good = 0-15 degrees 
Average = 16-30 degrees 
Poor = >3- degrees (reaching horizontal)
74
Q

List the prognosis from good, average and poor for position of the apex

A

Good = at the normal position
Average = above the 1st premolar
Poor - above the 2nd premolar

75
Q

What would indicate a poor prognosis for canine repositioning?

A
  • Crown tip above apices of the incisors, close to the midline and very mesioangular or horizontal angulation
76
Q

When can we not use traction to move ectopic canines?

A

If they are close to the incisor roots, as traction may result in destruction of the roots (we need a clear path of eruption)

Ortho (20 decks)

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