OS - impacted canines Flashcards
what is the second most commonly impacted tooth?
maxillary canine
1.7% prevalence
where are most ectopic canines found? and why?
80% palatal
tooth germ originates on the palatal side of the arch
where are maxillary canines palpable and at what age?
labial sulcus (and hard palate)
age 10-11
describe the aetiology of canine impaction
lack of space in the arch
the guidance plane is lost if the lateral incisor is traumatised
multifactorial inheritance
list factors that contribute to canine impaction
- 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
how would you clinically investigate canine eruption?
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
how may you radiographically assess canine impaction?
parallax films - 2 PAs, occlusal and DPT
CBCT
when investigating canine impaction, what does mobility of adjacent teeth imply?
external root resorption - their long term prognosis can be compromised
why may you want to use a CBCT to investigate canine impaction?
can see root resorption on palatal aspect of lateral incisor
when taking a horizontal parallax radiograph, explain the movement and what it means in relation to impaction?
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
what types of radiographs are used when taking a vertical parallax? and what does this show?
maxillary occlusal to localise and DPT
labial or buccal displacement
what does it mean if follicular space is enlarged? what is the normal diameter of follicular space?
cyst formation
should only be 3-4mm
what is a dilacerated tooth? and what causes it?
change in axis of root
caused by trauma when crown is forming
explain the sequelae of canine impaction?
resorption of incisor roots
cystic change
infection of cyst when close to the surface mucosa - possible sinus formation
what treatment can be performed if lat icisor is removed to allow canine to erupt?
canine reconstruction - makes it look like a lateral incisor
list the 5 types of treatment options for impacted canines?
conservative
interceptive
exposure
surgical removal
transplantation
when may you want to carry out conservative tx for impacted canines?
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)
what is the problem associated with leaving a C in place?
it will become very worn down as weaker tooth structure
if you build it up there will be poor crown to root ratio
when may you decide to perform interceptive treatment for impacted canines?
xLA deciduous canine
if pt 10-13 yrs, minimal crowding and space maintenance
if no change in position after 12 months on radiographs
what is the criteria for exposure and alignment tx?
well motivated pt with good OH
tooth not grossly displaced with favourable root morphology
what are the 2 techniques of exposure and alignment tx? what technique is favourable?
open technique = apically repositioned flap or palatal window
closed technique = orthodontic bracket and gold chain allowing orthodontic traction (favourable)
explain the open technique with an apically repositioned flap
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
what are the risks of an apically positioned flap using the open technique?
exposed canine roots subject to attrition, dentine sensitivity
describe the open technique to create a palatal window
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
what appliance can be placed following the open technique palatally to protect soft tissues?
dressing plate (acrylic) held on by adam’s cribs - lined with a soft tissue dressing (sedative)
what advice is given to pt recieving a dressing plate after the open technique for canine exposure and alignment?
wear plate for a week undisturbed
use mouthwash to keep area clean
brush teeth that are away from the site
what are gold chains used for in exposure and realignment surgery?
orthodontic traction
what is the criteria for surgical removal of impacted canines?
pt non compliant
pt satisfied with appearance of C or 2-4
advanced resorption of incisors (2/3rds)
malpositioned canine with difficult root morphology
describe the technique for surgical removal of impacted canines?
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
what is found in the incisive foramen?
neurovascular bundle
when may you have to sever the incisive foramen? what risk does this bring?
when surgically removing bilateral canines
risk - numbness of anterior part of hard palate
does numbness from severing the incisive foramen last?
no, overtime the greater palatine nerves will take over
what is always needed when using surgical drills for bone removal and why?
saline irrigation
if bone heated it will die
why must follicular tissue always be removed when surgically removing an impacted canine?
cystic change may occur if left behind
what are the requirements for autotransplantation?
poorly positioned canine without ankylosis
open apex desirable
adequate space and bone
describe the transplantation technique
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
what is the failure rate of transplantation?
30% over 9yrs
why may transplantation fail?
poor technique
internal resorption
external resorption - if excessive force on tooth in socket
replacement root resorption
infection
what would you do if an autotransplanted tooth shows internal resorption?
perform RCT post op
