The management of pa

latally displacedmaxillary canines: Considerations andchallengesElliott M. Moskowitz, DDS, MSd, and Ronniette C. Garcia, DDS

& 20141073-87http://d

DepartmDentistry, DDepartmentMedicine, DNY.

AddressFifth Avenu

46

This article opens with a recognition that ectopic maxillary canines may lead

to frank impactions requiring a coordinated andmultidisciplinary approach to

their surgical/orthodontic management and the potential benefit of manag-

ing canine ectopia, particularly palatally displaced canines, more conserva-

tively in their pre-eruptive ectopic positions in an effort to avoid impaction.

The prevalence of palatally displaced canines (PDC) in various populations

and corroborating as well as competing or conflicting opinions of etiology are

briefly reviewed. Some of the traditional as well as relatively newer

strategies and associated investigations of managing pre-eruptive palatally

displaced maxillary canines are discussed, and the imaging techniques

utilized to identify and locate ectopic maxillary canines are also discussed.

Early detection of ectopic canines must include at the very least panoramic

and/or periapical radiographs as part of any mixed dentition orthodontic

examination and assessment. The sometimes unpredictable continued path

of the ectopicmaxillary canine poses clinical and ethical issues to the clinician

when developing treatment strategies as part of any overall orthodontic

treatment plan for young patients presenting with maxillary canine ectopia.

The need for more thoughtful and carefully designed randomized clinical

trials with a greater emphasis on subject sample scrutiny is strongly

recommended to add much needed clarity to the clinical management of

ectopic maxillary canines. (Semin Orthod 2014; 20:46–58.) & 2014 Elsevier Inc.All rights reserved.

Introduction

T he impacted maxillary canine presents aunique challenge to both the orthodontist

and pediatric dentist. Most impacted maxillarypermanent canines are symptomless and patientsand parents of young patients are often unawareof such impactions until informed of this clinicalfinding by a dentist. Frequently, the maxillaryprimary canine will still be present and will posefar less of an esthetic concern than if the

Elsevier Inc. All rights reserved.46/12/1801-$30.00/0x.doi.org/10.1053/j.sodo.2013.12.005

ent of Orthodontics, New York University College ofiplomate American Board of Orthodontics, New York, NY;of Orthodontics, Columbia University College of Dentaliplomate American Board of Orthodontics, New York,

correspondence to Elliott M. Moskowitz, DDS, MSd, 11e, New York, NY 10003. E-mail: typodont@aol.com

Seminars in Orthodontics, Vol 20, N

maxillary primary canine had exfoliated. When afrank impacted permanent maxillary canine isdetected, the situation will frequently require acoordinated multidisciplinary orthodontic andoral surgical/periodontal procedure in order tobring the impacted tooth into the dental arch.Such routine procedures are not without occa-sional morbidity. Damage to adjacent teethduring the orthodontic traction process; com-promised periodontal support; most notablydecreased alveolar bone and soft tissue archi-tecture; and, although rare, potential ankylosis orinability to successfully move the impactedcanine tooth itself are potential adverse occur-rences associated with managing impactedmaxillary canines.

It has been stated and taught for many yearsthat the maxillary permanent canine by virtue ofits long path from initial development to its finalposition at the occlusal level is subject to dis-placements or degrees of ectopia that might

o 1 (March), 2014: pp 46–58

Palatally displaced maxillary canines 47

result in impaction.1 This anatomical circum-stance alone does not adequately explain theprecise etiology of maxillary canine impactionsor reasons for pre-eruptive maxillary canineectopia, which may be a strong predisposingfactor resulting in future impaction. Pre-eruptivemaxillary canine ectopia has also been associatedwith adverse effects upon the adjacent maxillarylateral incisors (and occasionally the centralincisors as well), causing varying degrees of rootresorption.2–4 Fig. 1 is a pre-treatment panoramicradiograph of a patient (age 11 years) withmultiple impactions. The maxillary left lateralincisor root has already been partially resorbedby the advancing ectopic maxillary left perma-nent canine.

This article will explore some of the currentlyrecommended treatment strategies intended toconservatively redirect ectopically developingpalatally displaced maxillary canines (PDC) intomore favorable eruptive positions with the overallintent of possibly avoiding or minimizing damageto adjacent structures as well as minimizing moreinvasive and costly surgical procedures associatedwith frank palatally impacted maxillary canines.

Prevalence and etiology

The prevalence of maxillary canine impactionhas a considerably wide range and largelydepends upon the ethnic and racial populationsstudied. Becker has cited a number of studies5

that included the lowest frequency reported in

Figure 1. The advancing ectopic left maxillary canine hincisor root.

the literature in Japan at 0.27%,6 the UnitedStates at 0.92%,7 and the Icelandic populationsurvey at 1.8%.8 Some corroborating findingsinclude 8% of all patients with maxillary canineimpactions having bilateral impactions and theincreased prevalence of impacted canines infemales to males of approximately 2:1 in theabove mentioned study of American patients7

and even 3:1 in a Welsh orthodontic group.9

There is a considerably higher incidence ofpalatally displaced canines (85%) than labiallypositioned impactions (15%).10,11

The definition of “impaction” varies consid-erably among clinicians. Perhaps Abron et al.12

most succinctly described impaction as aretardation or halt in eruption. Kuftinec andShapira13,14 more broadly defined impaction as a“condition in which a tooth is embedded in thealveolus and its spontaneous eruption is pre-vented by a local mechanical obstruction orposition of adjacent teeth.” Occasionally, thetooth loses its eruptive potential even though nophysical obstacle can be detected. Severalauthors define the latter condition as the “pri-mary,” and the former as the “secondaryimpaction.”

A number of theories have been proposed toexplain the etiology of palatally displaced per-manent maxillary canines. Genetic influenceshave been attributed to the prevalence of ectopicand impacted maxillary canines,15 while othershave favored a “guidance” influence thatmight be associated with missing, displaced, or

as already caused resorption of the maxillary lateral

Figure 2. An insufficient dental arch length frequently results in buccal displacement of maxillary canines.

Moskowitz and Garcia48

peg-shaped maxillary incisors, thereby deprivingthe developing maxillary canines of sufficientlateral incisor root surface to help guide theminto proper position.5 The authors speculate thatthis complex issue may be due to somecombination of both genetic (missing andsmall maxillary lateral incisors) and guidancefactors (the maxillary canine lacks theappropriate guidance from these atypicalvariations of missing, misplaced, or undersizedmaxillary lateral incisors) at some point of criticalcanine eruptive development workingsynergistically to eventually cause palatal dis-placement of the pre-eruptive maxillary canine.Further complicating theories attempting toexplain maxillary canine impaction as strictlygenetic or environmental etiologies are numer-ous other circumstances, which might includethe role that delayed dental maturation mightplay in contributing to palatally displaced max-illary canines.16 Other factors cited by Bishara17

include endocrine deficiencies, febrile diseases,irradiation, presence of an alveolar cleft,ankylosis, cystic or neoplastic formation, andidiopathic conditions with no apparent cause.

Although it might seem to be the mostintuitively derived etiology, Jacoby18 found thatdental arch length was not a causative factor in85% of palatally displaced maxillary canines.

Figure 3. An intraoral view of an 11-year-old male with aHowever, palpation could not detect a “canine bulge.”

Crowding in the maxillary dental arch, similar tothat in the patient in Fig. 2, will frequently resultin buccal displacement of the maxillarypermanent canine, many of which mayeventually erupt in a notably buccal position oron rarer occasions become impacted. The latterobserved clinical circumstance appears to justifynot grouping buccally and palatally displacedmaxillary canines together in investigations “toform a homogeneous sample of impacted teeth”since their etiologies appear to be distinctlydifferent.5

Can palatally displaced developingmaxillary canines be conservativelyredirected to normal pre-eruptivepositions?

Orthodontists and pediatric dentists are in thebest position to detect ectopically developingmaxillary permanent canines. The authors of thisarticle advocate that in addition to the clinicalexamination of patients in the mixed dentitionby the orthodontist or pediatric dentist, a pan-oramic radiograph is indispensable. Fig. 3 is anintraoral view of an 11-year-old male patient whohad been examined by his dentist periodicallybut had never received a panoramic radiograph.The occlusion extant could very well represent

seemingly unremarkable mixed dentition occlusion.

Figure 4. A panoramic radiograph detecting bilateral pre-eruptive ectopic maxillary canines.

Palatally displaced maxillary canines 49

what was once called “the ugly duckling stage” inwhich greater latitude in “awkwardness” of theocclusion and individual tooth position may beacceptable and expected to improve as thepatient transitions from the mixed dentitionstage to the adult permanent dentition. The lackof an expected “canine bulge” upon palpationand the panoramic radiograph obtained at thisdevelopmental stage, however, clearly suggestsotherwise (Fig. 4). The maxillary permanentcanines are obviously ectopic and appear to bewell on their way to frank impactions in the nearfuture. A relatively short period of a “Phase I”orthodontic treatment, which consisted solely ofmaxillary expansion as the only applianceutilized, and selective removal of primary teeth(maxillary primary canines) resulted in a morefavorable path of the pre-eruptive position of themaxillary permanent canines (Fig. 5), which

Figure 5. A significant improvement of maxillary

eventually led to the successful spontaneouseruption of the bilaterally ectopic maxillarypermanent canines (Fig. 6). Is such earlier ortimely intervention (orthodontic treatment inthe mixed dentition) a predictable andreproducible solution to managing potentiallyimpacted maxillary permanent canines? Andif so, is there any evidence-based or evidence-bolstered information that justifies suchintervention?

Imaging and palatally displaced maxillarypermanent canines

Although panoramic and/or periapical radio-graphs can be helpful in identifying supero-inferior and mesiodistal deviations of maxillarycanine positions, neither of these radiographsgives the precise 3-dimensional position of such

canines during Phase I orthodontic treatment.

Figure 6. The maxillary canines have erupted into the dental arch following limited Phase I orthodontictreatment.

Moskowitz and Garcia50

impacted teeth and would need to be supple-mented with additional periapical radiographs(Clark’s rule and/or Buccal-object rule) if moreprecise buccolingual positioning information isdesired.19,20 Additional images that mightinclude occlusal radiographs as well as extraoralimages, such as frontal and lateral cephalometricradiographs, can be helpful in better determin-ing the spatial relationship of an impactedmaxillary canine. The patient in Fig. 1 who hadpresented with a notable impaction of themaxillary left canine provides a somewhatdifferent perspective when the cephalometricradiograph (Fig. 7) is viewed, indicating that theincisal tip of the impacted canine is orientedtowards the anterior portion of the maxilla.Current cone beam technology (CBCT)indisputably offers the most comprehensiveimaging in determining both detailed and

Figure 7. A cephalometric radiograph showing a diffeconfirming the horizontal position and one where the in

accurate spatial relationships of an impactedtooth as well as detecting the extent of anydamage to adjacent structures such as themaxillary lateral, and, at times, the maxillarycentral incisors.21,2,3 Fig. 8 is a panoramicradiographic view of an impacted maxillaryright canine of a 16-year-old male. The CBCTimaging views (Fig. 9) illustrate the precise 3-dimensional relationship of the palatallyimpacted maxillary right canine at the surgicalexposure and placement of the orthodonticattachment (Fig. 10).

Orthodontists have also attempted to judgethe severity of maxillary canine ectopia by thedegree of mesiodistal location of the crown andthe angulation as measured on a panoramicradiograph. The intent of the latter was perhapsto predict the future success of interceptivestrategies aimed at redirecting the eruptive path

rent perspective of an impacted maxillary canine,cisal tip is oriented anteriorly.

Figure 9. Subtracted CBCT views of the patient shown in Fig. 8 more precisely locate the actual spatial relationshipof the impacted maxillary right canine tooth.

Figure 8. A panoramic radiograph of a16-year-old male with an impacted maxillary right permanent canine.

Palatally displaced maxillary canines 51

Figure 10. An image obtained at the time of surgical exposure and orthodontic attachment placement (of thepatient in Figs. 8 and 9) showing the precise location of the impacted maxillary right canine.

Moskowitz and Garcia52

of palatally displaced maxillary permanent can-ines.22–24 Fig. 11 shows ectopic canines and thedegree of angulation to the midline as well as thesector scheme as presented by Lindauer et al.25

Sector I is the area distal to a line tangent to thedistal heights of the contour of the lateral incisor

Figure 11. The angular relationship of the ectopic caninedetermine the degree of severity of the ectopia.

crown and root. Sector II is mesial to sector I butdistal to a line bisecting the mesiodistaldimension of the lateral incisor along the longaxis. Sector III is mesial to sector II but distal to aline tangent to the mesial heights of the contourof the lateral incisor crown and root. Sector IV

long axis to the midline and sector allocation used to

Palatally displaced maxillary canines 53

includes all areas mesial to sector III. Lindauer,in the same study, concluded that up to 78% ofthe canines that had cusp tips located in sectors IIthrough IV were destined to become impacted.Warford et al.24 found that sector locationprovided the greatest information on futureimpaction with angulation providing very littlestatistically predictive value.

Strategies utilized to redirect pre-eruptiveectopic maxillary displaced canines

Clinicians have advocated the removal of primarycanines associated with palatally displaced max-illary permanent canines as an interceptivemeasure intended to redirect the ectopic caninesinto more favorable pre-eruptive positions.25–27

More recently, Bonetti et al.27,28 have advocated a“double extraction” procedure involving theremoval of both the primary canines andprimary first molars and reported a higherdegree of positive effects in redirecting ectopiccanines.

Leonardi et al.29 investigated 2 interceptiveapproaches to the treatment of palatallydisplaced maxillary canines. Their samples con-sisted of 3 distinct groups. Group 1 consisted of asample that underwent the extraction of themaxillary deciduous canines as a sole treatmentmeasure. Group 2 received in addition to theremoval of the deciduous canines the use of acervical pull headgear. Group 3 was an untreatedcontrol group. The removal of the deciduous

Figure 12. Ectopically developing maxillary and mand

canine as an isolated measure to intercept palataldisplacement of the maxillary canines showed aprevalence rate of 50% success. It is interesting tonote that the success rate of this group was notsignificantly greater than the untreated controls.The group that received extractions of thedeciduous canines as well as the use of head-gear had a successful eruption of the permanentcanines in 80% of the cases. In a subsequentstudy, Baccetti et al.30 investigated theeffectiveness of rapid maxillary expansion in asample of palatally displaced maxillary canines inthe early mixed dentition. A group that receivedno treatment served as a control. The group thatreceived RME showed a successful eruption rateof 65.7%, while the group that received notreatment experienced a 13.6% successfuleruption of the displaced maxillary canines.

Current clinical problems

Interpreting the clinical relevance of thesestudies poses numerous problems for the clini-cian. The design of many of these investigations isfrequently very different and, understandably,conflicting conclusions could result. Schindeland Duffy31 reported an association betweenpotentially impacted canines and transversediscrepancies, while Langberg and Peck32

refute this finding in their investigation. Fewstudies have included control samples composedof patients receiving no treatment due in manyinstances to either logistic or ethical issues

ibular canines in a female patient aged 10.5 years.

Figure 13. A panoramic radiograph of the patient shown in Fig. 12, 27 months after the initial radiograph hadbeen taken. The canines had erupted normally, the patient having received no treatment.

Moskowitz and Garcia54

associated with developing such potentiallyuseful samples. The investigations by Baccettiet al.29,30 are particularly intriguing to the clini-cian because their study observations (no treat-ment control samples included) validate theclinician’s empirical observations that a certainpercentage of patients who present with palatallydisplaced maxillary canines will self-correctwithout any treatment. This presents an ethicalchallenge to the orthodontist in developing aviable treatment philosophy of addressingectopically erupting canines earlier (mixeddentition) rather than later and the benefit; atthe very least of what might be called “activeobservation” for such patients who present early,but with mild ectopic positions of maxillarycanines. Fig. 12 is a panoramic radiograph of afemale patient 10.5 years of age, with pre-eruptivemaxillary and mandibular permanent canines ofsome concern due to their ectopic positions. Theparent rejected any interceptive treatment aimedat addressing the ectopic canines but returned tothe office approximately 27 months later. Thepanoramic radiograph taken at that time(Fig. 13) shows a complete correction without

Figure 14. An intraoral view of a 10-year-old patien

any treatment. Conversely, the patient illustratedin Fig. 14 was a 10-year-old female with excessivespacing in the mixed dentition, relatively smallmaxillary incisors, long unresorbed primarymaxillary canine roots, and no evidence of alabial canine bulge upon palpation. The degreeof ectopia of the maxillary right and left caninesand the unresorbed roots of the maxillary pri-mary canine roots (Fig. 15) warrantedconsideration for intervention. The parentrejected treatment at this time but returnedprecisely one year later. The ectopia and rootmaturation of the maxillary canines advanced(Fig. 16) and the patient eventually receivedcomprehensive orthodontic treatment, includingbilateral canine exposures and subsequentorthodontic traction of these teeth becomingnecessary. The unpredictability of maxillarycanine development in spite of the previouslymentioned studies, and the attempts at theprediction of both continued and advancingectopia as well as success in response toorthodontic treatment, is illustrated in thetreatment of a male patient 11 years of age,who presented with an occlusion that was not too

t with excessive spacing in the mixed dentition.

Figure 15. A panoramic view of a patient showing bilateral maxillary permanent left and right canine ectopia.

Palatally displaced maxillary canines 55

disparate from a normally developing occlusionin the mixed dentition (Fig. 17). The panoramicradiograph (Fig. 18) revealed severe ectopia ofthe maxillary right canine with respect toincreased angulation and crown location insector IV, suggesting a poor prognosis for earlyinterceptive guidance into more favorable pre-eruptive positions. The maxillary left canine was“mildly” ectopic by comparison. The patient wasinitially treated with a fixed palatal expanderfollowed by fixed appliances. Fig. 19 is apanoramic view and images in Fig. 20 areintraoral views of the patient during an interimstage of comprehensive orthodontic treatment inwhich the maxillary canines successfully eruptedinto the oral cavity and dental arch. Noextractions of primary teeth were employed.

Figure 16. A panoramic view of the patient illustrated in Fis advancing ectopia and eventual frank impaction requir

The authors’ clinical guidelines include thefollowing:

(1)

ig. 15ing s

Clinical examination of young patients at 8or 9 years of age.

(2)

Panoramic screening radiograph to observeunderlying dental development.

(3)

Assessment of any possible ectopia. (4) Decision to intervene or continue to observe

at 6–8-month intervals.

(5) Discussion with the parents of young patients

of the considerations of early orthodontictreatment, which is generally planned as aPhase I treatment often followed by a PhaseII treatment, and numerous other cost/risk/benefit factors associated with any Phase Itype of treatment, particularly, treatment

exactly 1 year after the initial examination. Thereurgical exposures and orthodontic traction.

Figure 17. A patient, 11 years of age, with a relatively unremarkable mixed dentition occlusion.

Figure 18. The panoramic radiograph of the patient illustrated in Fig. 17 reveals a severely ectopic maxillary rightcanine, suggesting a poor prognosis for conservative interceptive treatment.

Figure 19. A panoramic view of the patient (Figs. 17 and 18) at an interim stage of comprehensive orthodontictreatment showing spontaneous successful eruption of the maxillary canines.

Figure 20. Intraoral views of the patient at the same time point as Fig. 19, showing the maxillary canines eruptedinto the dental arch.

Moskowitz and Garcia56

Palatally displaced maxillary canines 57

that may be initiated largely because ofdetected palatally displaced maxillarycanines.

(6)

Selection of a specific treatment protocol(extractions of primary teeth) and use ofadjunctive appliances (expanders andheadgear).

The selection of a specific protocol for indi-vidual patients with PDC remains, at this junc-ture, exceedingly challenging in light of thefindings and interpretations of the variousinvestigations published, as well as the opinionsand clinical experience of the clinicians. In asurvey of 100 consecutively observed and/ortreated young patients at the authors’ office withmaxillary canine ectopia of varying degrees, over88% were able to be redirected to normaleruptive positions. This clinical group receivedobservation, primary canine removal, and pri-mary canine and primary first molar removal(double extraction technique) combined, attimes, with palatal expanders in some instancesin the absence of transverse discrepancies. Therewas no single predictable factor that could beidentified or specific treatment modality thatcould be recommended as a reproducible strat-egy that could be applied to every patient. Thelimitations of such clinical and obviously filteredobservations would be too numerous to mention,but the “success” of a more aggressive approachto the management of ectopic canines may insome respects parallel the dilemma associatedwith the selection of specific mechanotherapyand appliances in the Class II patient. Fur-thermore, it might be that some disruption in thehomeostasis of the existing clinical condition(Class II relationship) during periods of activegrowth have resulted in the resolution of suchmalocclusions, accounting for the efficacy of somany seemingly different orthodontic appli-ances. Similarly, it appears that a disruption inthe status quo of the developing young patientwith maxillary canine ectopia with methodsdescribed in this article might result in a greaterpercentage of successfully redirected ectopicteeth than doing nothing at all. As always, thechallenge for the clinician remains in developingpredictable and reproducible strategies forindividual patients presenting with palatally dis-placed maxillary canines that will result in a

substantially high success rate for redirection ofthese ectopic teeth.

Concluding remarks

There is a profound need for greater clarity andunderstanding of the etiology of maxillary canineectopia, particularly, the causative factors ofpalatally displaced canines. With such clarity,perhaps more predictable and reproduciblestrategies can be developed, which would benefitindividual patients with earlier-detected ratherthan later-detected maxillary canine ectopia.Although admittedly, by way of meta-analysis ofmany past studies of varying quality and empiricalobservations, some insight has been gained ofboth etiology and efficacy of active interventionin cases of maxillary canine ectopia, there is adistinct need for more carefully designed pro-spective randomized clinical trials in this area tofacilitate separating the “gold from the dross.”Until such investigations are concluded, weremain empirically bound in desperate need formore real science upon which to base our clinicaldecisions.

References1. Dewel BF. The Upper Cuspid: Its Development and

Impaction. Angle Orthod. 1949;19(2):79–90.2. Ericson S, Kurol J. Resorption of incisors after ectopic

eruption of maxillary canines: a CT study. Angle Orthod.2000;70:415–423.

3. Ericson S, Kurol J. Incisor root resorption due to ectopicmaxillary canines imaged by computerized tomography: acomparative study in extracted teeth. Angle Orthod.2000;70:276–283.

4. Ericson S, Kurol J. Resorption of maxillary lateral incisorscaused by ectopic eruption of the canines: a clinical andradiographic analysis of predisposing factors. Am J OrthodDentofacial Orthop. 1988;94:503–513.

5. Becker A. The Orthodontic Treatment of Impacted Teeth. 2nded., United Kingdom: Informa Healthcare; 2007[pages 93and 97].

6. Takahama Y, Aiyama Y. Maxillary canine impaction as apossible microform of cleft lip and palate. Eur J Orthod.1982;4:275–277.

7. Dachi SF, Howell FV. A survey of 3874 routine full mouthradiographs. II. A study of impacted teeth. Oral Surg OralMed Oral Pathol. 1961;14:1165–1169.

8. Thilander B, Jacobson SO. Local factors in impaction ofmaxillary canines. Acta Odontol Scan. 1968;26:145–168.

9. Oliver RG, Mannion JE, Robinson JM. Morphology of themaxillary lateral incisor in cases of unilateral impaction ofthe maxillary canine. Br J Orthod. 1989;16:9–16.

10. Shapira Y, Kuftinec MM. Early diagnosis and interceptionof potential maxillary canine impaction. J Am Dent Assoc.1998;129:1450–1454.

Moskowitz and Garcia58

11. Sambataro S, Baccetti T, Franchi L, Antonini F. Earlypredictive variables for upper canine impaction asderived from posteroanterior cephalograms. Angle Orthod.2005;75:28–34.

12. Abron A, Mendro R, Kaplan S. Impacted permanentmaxillary canines. N Y State Dent J. 2004;70:24–28.

13. Kuftinec MM, Shapira Y. The impacted maxillary canine:review of concepts. ASDC J Dent Child. 1995;62(5):317–324.

14. Personal communications with MM Kuftinec and YShapira, August 2013.

15. Peck S, Peck L, Kataja M. The palatally displaced canineas a dental anomaly of genetic origin. Angle Orthod. 1994;64(4):249–256.

16. Becker A, Chaushu S. Dental age in maxillary canineectopia. Am J Orthod Dentofacial Orthop. 2000;17:657–662.

17. Bishara S. Impacted maxillary canines: a review. Am JOrthod Dentofacial Orthop. 1992;101:159–171.

18. Jacoby H. The etiology of maxillary canine impactions.Am J Orthod. 1983;84:125–132.

19. Langland OE, Francis SH, Langlois RD. Textbook of DentalRadiology. Chapter 15. Atlas of Special Technics In DentalRadiology. Springfield, IL: Charles C Thomas; 1984.

20. Ericson S, Kurol J. Radiographic examination of ectopi-cally erupting maxillary canines. Am J Orthod DentofacialOrthop. 1987;91:483–492.

21. Mah J, Alexandroni S. Cone-beam computer tomographyin the management of impacted canines. Semin Orthod.2010;16(3):199–203.

22. Ericson S, Kurol J. Early treatment of palatally eruptingmaxillary canines by extraction of the primary canines.Eur J Orthod. 1988;10:283–295.

23. Power SM, Short MB. An investigation into the responseof palatally erupting displaced canines to the removal ofdeciduous canines and an assessment of factors contri-buting to favourable eruption. Br J Orthod. 1993;20:215–223.

24. Warford JH, Grandhi RK, Tira DE. Prediction of maxillarycanine impaction using sectors and angular measure-ment. Am J Orthod. 2003;124:651–655.

25. Lindauer SJ, Rubenstein LK, Hang WM, Andersen WC,Isaacson RJ. Canine impaction identified earlywith panoramic radiographs. J Am Dent Assoc. 1992;123:91–97.

26. Jacobs SG. Reducing the incidence of unerupted palatallydisplaced canines by extraction of deciduous canines: thehistory and application of this procedure with some casereports. Aust Dent J. 1998;43:20–27.

27. Alessandri Bonetti G, Zanarini M, Incerti Parenti S, et al.Preventive treatment of ectopically erupting maxillarypermanent canines by extraction of deciduous caninesand first molars: a randomized clinical trial. Am J OrthodDentofacial Orthop. 2011;139(3):316–323.

28. Alessandri Bonetti G, Incerti Parenti S, ZanariniM,Marini I.Double vs. single teeth extraction approach as preventionof permanent maxillary canines ectopic eruption. PediatrDent. 2010;32:407–412.

29. Leonardi M, Armi P, Franchi L, Baccetti T. Twointerceptive approaches to palatally displaced canines:a prospective longitudinal study. Angle Orthod. 2004;74:581–586.

30. Baccetti T, Mucedero M, Leonardi M, Cozza P. Inter-ceptive treatment of palatal impaction of maxillarycanines with rapid palatal expansion: a randomizedclinical trial. Am J Orthod Dentofacial Orthop.. 2009;139:657–661.

31. Schindel RH, Duffy SL. Maxillary transverse discrepanciesand potentially impacted maxillary canines in mixed-dentition patients. Angle Orthod. 2007;77:430–435.

32. Langberg BJ, Peck S. Adequacy of maxillary dental archwidth in patients with palatally displaced canines. Am JOrthod Dentofacial Orthop. 2000;118(2):220–223.