the unerupted maxillary canine Flashcards
(35 cards)
what is the prevalence of ectopic canines?
> 2% of the population
> palatally = 61%
line of arch = 34%
buccal = 4.5%
what is the ratio of unilateral to bilateral ectopic canines?
> 4 : 1
is ectopic canines more common in females than males ?
> females (70%)
when are ectopic canines more likely to occur?
> when a patient has a class II div 2 malocclusion
what is the primary problem of ectopic canines?
> it can cause root absorption of the adjacent tooth
what tooth is most likely to be affected by root resorption by an ectopic canine?
> lateral incisor
> but can be multiple teeth (if lateral is missing, central is at risk)
what is the best methods in measuring root resorption?
- CBCT
- CT
- plane R/G (as 2D unable to fully show palatal resorption)
why does an ectopic canine happen ?
> Crowding/shortening of arch length (common for buccal) (Jacoby, 1983)
> Adjacent lateral incisor missing or abnormal in shape or size
> Long path of eruption (Brin et al., 1986)
> Palatal = genetic; buccal = inadequate arch space
what did the Brin et al study find on ectopic canines?
> 43 % of test subjects had absent or small incisors
> length of the root more critical than crown size as the root guides the canine into position
what should you do if the canine is not palpable buccally at 9-10 years?
- Check – bulge, inclination and colour of adjacent teeth.
- Palpate – for the canine crown buccally and palatally, check for mobility of the 2 and C.
- Radiographs – Presence, Position, Pathology (root resorption/ cyst formation)
what is parallax radiograph technique?
> an apparent change in the position of an object resulting from a change in position of the observer.
> The principle of parallax can be used to determine the position of an unerupted tooth relative to its neighbours.
when do we use the parallax technique?
> Dentists should be palpating for canines when a patient is 9-10 years old.
> Index of suspicion is raised if the pt has a missing, or abnormally shaped lateral incisor; has spaced arches, or if palpation indicates an asymmetrical eruption pattern
what are the clinical signs of a palatally impacted canine?
> Delayed eruption of 3 or prolonged retention of the C
> Absence of normal labial 3 bulge or presence of a palatal bulge in the 3 region.
> Delayed eruption, distal tipping of migration of the lateral incisor.
> Loss of vitality and increased mobility of the central or lateral incisor
why do we use the parallax technique?
> Knowing the location of the ectopic canine allows us to treatment plan more accurately.
> If not managed correctly an ectopic canine may resorb the root of the adjacent incisors. This may result in a medico-legal encounter.
how do we take horizontal parallax?
> two IOPAs - at least 20 degrees of tube shift needed
> Anterior occlusal and an IOPA
how do we take vertical parallax
> anterior occlusal and DPT
> IOPA and DPT
how do you interpret parallax?
> if the canine moves with the beam its placed palatally , (the furthest away object will move with the beam) (with it pal)
> if it doesn’t move its in the line of arch
what is better to use, horizontal or vertical parallax?
> In a study of 39 patients Armstrong et al. 2003 found that 69% of palatal ectopic canines were correctly located with VP, compared to 88% with HP.
> Both came back with 63% accuracy for buccal ectopic canines.
> The paper suggested that DPTs shouldn’t be used in the investigation of canine ectopia, where radiographs that allow the use of HP should be taken.
what did the Ericsson & Karol study find out about ectopic canines?
> non crowded dentition
> extraction of deciduous canines yielded a 78% of self correcting an ectopic canine
> however If the lateral incisor root is in the way this greatly decreases the chance of self correction
what did the power and short study find out about ectopic canines?
> crowded dentition
> removal of the deciduous canine yielded = 62% self corrected, 19% improved, 19% no change
> crowding reduced the dentition
what did the Leonard et al find out about ectopic study?
> Longitudinal prospective controlled study
> Isolated extraction of C = 50% success
> Untreated control group = 50% success
> Creation of more space + extraction of C = 80% success
when would you extract a deciduous canine in a patient?
> 10-13 years
what do you have to consider when extracting a deciduous canine?
> consider the need for a balancing extraction
> it is better if there is no crowding
> consider the use of an URA or headgear to create space
> if no improvement in 12 months then other options should be considered
why would you leave the decision of extraction of a deciduous canine to a specialist orthodontist?
> this will often be the treatment of choice
> however, ectopic canine may not be align-able and you may have extracted a highly useful tooth
> you’ll be left with a space if done wrong, always make a referral
