OS - impacted canines

Question 1

what is the second most commonly impacted tooth?

Answer 1

maxillary canine
1.7% prevalence

Question 2

where are most ectopic canines found? and why?

Answer 2

80% palatal
tooth germ originates on the palatal side of the arch

Question 3

where are maxillary canines palpable and at what age?

Answer 3

labial sulcus (and hard palate)
age 10-11

Question 4

describe the aetiology of canine impaction

Answer 4

lack of space in the arch
the guidance plane is lost if the lateral incisor is traumatised
multifactorial inheritance

Question 5

list factors that contribute to canine impaction

Answer 5

• non-resorption of deciduous teeth
• ankylosis of impacted canine (consequence of trauma to deciduous tooth)
• contraction/ collapsed maxillary arch (they are the last teeth to erupt
• absence of lateral incisor to guide eruption
• pathology
• scar tissue if deciduous removed early
• root formation at angle to crown due to trauma
• cleft lip and palate, syndromes, cleidocranial dysplasia
• long path of eruption 22mm
• displacement of the crypt

Question 6

how would you clinically investigate canine eruption?

Answer 6

palpate labial sulcus and hard palate
evidence of rotation/ tilting of adjacent teeth
both should erupt at same time (no more than 6 months apart)
mobility/ sensibility of adjacent teeth
deciduous canine should shed
ask parents - it is familial

Question 7

how may you radiographically assess canine impaction?

Answer 7

parallax films - 2 PAs, occlusal and DPT
CBCT

Question 7

when investigating canine impaction, what does mobility of adjacent teeth imply?

Answer 7

external root resorption - their long term prognosis can be compromised

Question 8

why may you want to use a CBCT to investigate canine impaction?

Answer 8

can see root resorption on palatal aspect of lateral incisor

Question 9

when taking a horizontal parallax radiograph, explain the movement and what it means in relation to impaction?

Answer 9

if impacted tooth moves in the same direction - it is further away - palatal impacted
if impacted tooth moves in the opposite direction - it is buccally impacted

Question 10

what types of radiographs are used when taking a vertical parallax? and what does this show?

Answer 10

maxillary occlusal to localise and DPT
labial or buccal displacement

Question 11

what does it mean if follicular space is enlarged? what is the normal diameter of follicular space?

Answer 11

cyst formation
should only be 3-4mm

Question 12

what is a dilacerated tooth? and what causes it?

Answer 12

change in axis of root
caused by trauma when crown is forming

Question 13

explain the sequelae of canine impaction?

Answer 13

resorption of incisor roots
cystic change
infection of cyst when close to the surface mucosa - possible sinus formation

Question 14

what treatment can be performed if lat icisor is removed to allow canine to erupt?

Answer 14

canine reconstruction - makes it look like a lateral incisor

Question 15

list the 5 types of treatment options for impacted canines?

Answer 15

conservative
interceptive
exposure
surgical removal
transplantation

Question 16

when may you want to carry out conservative tx for impacted canines?

Answer 16

if the deciduous C is still there and healthy
pt in unwilling to have ortho
adjacent teeth still vital
pt happy with appearance with good contact between the 2 and 4
radiographs show tooth very high with no pathology or resorption (usual after 14yrs)

Question 17

what is the problem associated with leaving a C in place?

Answer 17

it will become very worn down as weaker tooth structure
if you build it up there will be poor crown to root ratio

Question 18

when may you decide to perform interceptive treatment for impacted canines?

Answer 18

xLA deciduous canine
if pt 10-13 yrs, minimal crowding and space maintenance
if no change in position after 12 months on radiographs

Question 19

what is the criteria for exposure and alignment tx?

Answer 19

well motivated pt with good OH
tooth not grossly displaced with favourable root morphology

Question 20

what are the 2 techniques of exposure and alignment tx? what technique is favourable?

Answer 20

open technique = apically repositioned flap or palatal window
closed technique = orthodontic bracket and gold chain allowing orthodontic traction (favourable)

Question 21

explain the open technique with an apically repositioned flap

Answer 21

3 sided flap raised
take away tissue overlying crown of tooth (bone and follicular tissue)
suture gingivae at a higher position to leave path of eruption unimpeded

Question 22

what are the risks of an apically positioned flap using the open technique?

Answer 22

exposed canine roots subject to attrition, dentine sensitivity

Question 23

describe the open technique to create a palatal window

Answer 23

list palatal mucoperiosteum
bone removal to expose maximum bulbosity to cingulum
window cut in soft tissue
ortho can bond bracket on or wait for spontaneous eruption

Question 24

what appliance can be placed following the open technique palatally to protect soft tissues?

Answer 24

dressing plate (acrylic) held on by adam’s cribs - lined with a soft tissue dressing (sedative)

Question 25

what advice is given to pt recieving a dressing plate after the open technique for canine exposure and alignment?

Answer 25

wear plate for a week undisturbed
use mouthwash to keep area clean
brush teeth that are away from the site

Question 26

what are gold chains used for in exposure and realignment surgery?

Answer 26

orthodontic traction

Question 27

what is the criteria for surgical removal of impacted canines?

Answer 27

pt non compliant
pt satisfied with appearance of C or 2-4
advanced resorption of incisors (2/3rds)
malpositioned canine with difficult root morphology

Question 28

describe the technique for surgical removal of impacted canines?

Answer 28

commonly palatal - so same flap as per exposure technique - envelope flap
if buccal - 3 sided or 2 sided flap
section if root morphology complex or position tight against adjacent teeth

Question 29

what is found in the incisive foramen?

Answer 29

neurovascular bundle

Question 30

when may you have to sever the incisive foramen? what risk does this bring?

Answer 30

when surgically removing bilateral canines
risk - numbness of anterior part of hard palate

Question 31

does numbness from severing the incisive foramen last?

Answer 31

no, overtime the greater palatine nerves will take over

Question 32

what is always needed when using surgical drills for bone removal and why?

Answer 32

saline irrigation
if bone heated it will die

Question 33

why must follicular tissue always be removed when surgically removing an impacted canine?

Answer 33

cystic change may occur if left behind

Question 34

what are the requirements for autotransplantation?

Answer 34

poorly positioned canine without ankylosis
open apex desirable
adequate space and bone

Question 35

describe the transplantation technique

Answer 35

access as for removal
atraumatic elevation avoiding contact with PDL/ root
tooth ‘parked’ in tissues whilst the socket is prepared with bur or chisels
socket ‘friction-fit’
may require splint immobilisation
must be free of occlusion
post op check vitality and resorption

Question 36

what is the failure rate of transplantation?

Answer 36

30% over 9yrs

Question 37

why may transplantation fail?

Answer 37

poor technique
internal resorption
external resorption - if excessive force on tooth in socket
replacement root resorption
infection

Question 38

what would you do if an autotransplanted tooth shows internal resorption?

Answer 38

perform RCT post op