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CASE REPORT
Complications of misdiagnosis of maxillarycanine ectopic eruption
Daniela GambaGarib,a Guilherme Janson,b Taiana deOliveira Baldo,c and Patr�ıcia Bittencourt Dutra dos Santosc
Bauru, S~ao Paulo, Brazil
FromPauloaAssobProfecPostgThe aucts oReprinDenta9-75,Subm0889-Copyrdoi:10
256
Ectopic eruption of maxillary canines can be associated with root resorption of adjacent teeth. This case reportdescribes and discusses an interesting case of a 15-year-old girl with a Class III malocclusion and an impactedmaxillary canine. Because of the unfavorable position of the ectopic canine and the severe root resorption of themaxillary left central and lateral incisors, the treatment options included extraction of the maxillary permanentcanines. The mandibular first premolars were extracted to compensate for the Class III malocclusion. A pano-ramic radiograph taken earlier in the mixed dentition already indicated a possible eruption disturbance of themaxillary left permanent canine. The importance of early diagnosis of maxillary canine ectopic eruption is high-lighted in this case report. The early identification of radiographic signs of an ectopic pathway of eruption shouldbe followed by deciduous canine extraction to prevent canine retention andmaxillary incisor root resorption. (AmJ Orthod Dentofacial Orthop 2012;142:256-63)
Maxillary permanent canines show the highestfrequency of impaction, excluding the thirdmolars.1,2 According to previous reports, the
prevalence of maxillary canine impaction ranges from0.9% to 2.5%.2-5 Although this might seem to bea relatively small prevalence, it is speculated that, inclinical orthodontic practice, the frequency might behigher.6
The diagnosis and assessment of the extent of max-illary incisor resorption are fundamentally important forthe prevention of impaction and the reduction of subse-quent complications of canine eruption.7 Panoramicradiographs can provide worthwhile information regard-ing the presence and general location of maxillary canineectopic eruption in the late mixed dentition.5 In approx-imately 80% of patients with impacted canines, the cusptips overlap the lateral incisor roots during the mixeddentition, as observed in panoramic radiographs.5,8
Ericson and Kurol9 reported that extraction of themaxillary deciduous canines has a favorable effect on
the Department of Orthodontics, Bauru Dental School, University of S~ao, Bauru, S~ao Paulo, Brazil.ciate professor.ssor and head.raduate student.uthors report no commercial, proprietary, or financial interest in the prod-r companies described in this article.t requests to: Daniela Gamba Garib, Department of Orthodontics, Baurul School, University of S~ao Paulo, Alameda Oct�avio Pinheiro BrisollaBauru, S~ao Paulo 17012-901, Brazil; e-mail, [email protected], September 2010; revised and accepted, December 2010.5406/$36.00ight � 2012 by the American Association of Orthodontists..1016/j.ajodo.2010.12.023
maxillary canine ectopic eruption in most patients(78%), if extraction treatment is performed in time, be-tween 10 and 13 years of age.
Root resorption of the maxillary permanent incisorsrelated to maxillary canine ectopic eruption is probablycaused by inherent pressure from migration of the dis-placed erupting canine combined with physical contactbetween the root of the incisor and the prominence ofthe canine crown.10 Associated root resorption of max-illary permanent incisors occurs in 48% of childrenwith maxillary canine ectopic eruption between 9 and15 years of age, and it is often a serious complication,prolonging orthodontic treatment in many patients.11,12
Early diagnosis and intervention could avoid theseunfavorable effects. Therefore, the aim of this casereport of a patient with severe root resorption of themaxillary incisors related to a palatally displacedcanine is to highlight the importance of early diagnosisof maxillary canine ectopic eruption.
DIAGNOSIS AND ETIOLOGY
A 15-year-old girl in the permanent dentition soughtorthodontic treatment because of dental crowding in thefirst author's private office. The patient was unhappyabout the appearance of her smile (Fig 1). At the firstappointment, her parents reported that she had alreadyhad previous orthodontic treatment with maxillaryexpansion and facial mask therapy at 8 years of age.
The facial analysis showed a mild Class III skeletalrelationship (Fig 2). The intraoral examination revealeda mild Class III molar occlusion with an anterior
Fig 1. Pretreatment facial and intraoral photographs.
Fig 2. Pretreatment cephalometric tracing.
Garib et al 257
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edge-to-edge relationship, bilateral posterior crossbite,mild mandibular and severe maxillary dental crowding,and an unerupted maxillary left canine. The maxillaryright canine was labially displaced (Fig 3). The patient’soral hygiene was excellent.
The panoramic radiographic examination confirmedthe impaction of the maxillary left canine, which hadcomplete root formation (Fig 4). Periapical radiographsshowed severe resorption of the maxillary incisor roots,especially the central incisor, and 2 periapical radio-graphs taken with Clark's technique confirmed thepalatal displacement of the impacted tooth (Fig 5).
The patient had been previously treated with maxil-lary expansion and facial mask therapy in the mixeddentition to correct the Class III malocclusion. Thepanoramic radiograph of the mixed dentition showedsigns of ectopic eruption of the maxillary left permanentcanine according to the study of Lindauer et al5 (Fig 6).
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Fig 3. Pretreatment orthodontic models.
Fig 4. Pretreatment panoramic radiograph.
Fig 5. Two periapical radiographs taken with the Clarktechnique confirmed the palatal displacement of the max-illary left canine.
258 Garib et al
TREATMENT OBJECTIVES
The treatment goals were to manage the impactedcanine; correct the Class III malocclusion, the anterioredge-to-edge relationship, the posterior crossbite, andthe dental crowding; and improve her smile. Thepatient's facial esthetics were acceptable and could bemaintained.
TREATMENT ALTERNATIVES
One treatment option consisted of maxillaryexpansion, extraction of the 4 first premolars, surgicalexposure, and traction of the maxillary left canine.
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The second treatment option included maxillaryexpansion, and extractions of the mandibular firstpremolars, and the maxillary right first premolar andleft canine.
The third treatment option included maxillaryexpansion, extractions of the mandibular first premolarsand the maxillary right and left canines. The first premo-lars would replace the canines. This was the selectedalternative because of the poor prognosis for caninetraction and to obtain symmetry of the anterior sectionof the maxillary arch.
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Fig 6. Panoramic radiograph in the intertransitory periodof themixed dentition. Observe the superimposition of theunerupted maxillary left canine and the maxillary leftlateral incisor root already visible in the early mixeddentition.
Garib et al 259
TREATMENT PROGRESS
The maxillary arch was expanded with a hyrax ex-pander. Four months after the expansion, the expanderwas removed, and the mandibular first premolars andthe maxillary canines were extracted. Preadjusted0.022 3 0.025-in fixed appliances were used. Sectionalmechanics was used to retract the mandibular canines tomaintain the incisor sagittal position (Fig 7). A lipbumper was installed to reinforce anchorage in the man-dibular arch. After initial mandibular canine retraction,the incisors were bonded, and leveling and alignmentwith nickel-titanium archwires (0.012, 0.014, and0.016 in), followed by stainless steel archwires (0.018,0.020, and 0.019 3 0.025 in) in both arches, wereinitiated.
Anterior retraction in the mandibular arch was per-formed with rectangular stainless steel archwires(0.0193 0.025 in) and Class III elastics (Fig 8). The ClassIII elastics also produced mesial drift of the maxillaryposterior teeth to close the additional extraction spaceswithout moving the maxillary incisors, which had shortroots. Conventional orthodontic finishing procedureswere then undertaken. The total treatment time was32 months. Retention consisted of a circumferentialretainer in the maxillary arch and a bonded canine-to-canine retainer in the mandibular arch.
RESULTS
The orthodontic treatment produced excellent im-provement of the dental esthetics as well as correctionof the dental problems. The facial photographs and thecephalometric tracing show that the posttreatmentprofile was satisfactory with slight changes only in lipposition (Figs 9 and 10). The patient was satisfied withher smile and facial esthetics. The final occlusion
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showed Class I canine and molar relationships on bothsides (Fig 11). The changes were confirmed in the super-imposed pretreatment and posttreatment lateral cepha-lometric tracing (Fig 12). The final radiographs showedthat the maxillary incisor roots remained unchanged(Figs 13 and 14). The patient's parents were advisedthat the unerupted third molars would probably needto be extracted in the future.
DISCUSSION
Maxillary canines have the longest period of develop-ment, as well as the longest and most tortuous eruptionpathway until reaching occlusion.13 Consequently, theseteeth are more prone to have eruption disturbancesduring the mixed dentition.
Two major theories have been proposed to explainthe occurrence of palatally displaced maxillary canines:guidance and genetic.14 According to the guidance the-ory, local conditions are responsible for the displacementof maxillary canines.15-17 While erupting, the caninelacks (from hypoplasia or agenesis of the lateralincisor) the guidance that, in normal conditions, wouldbe provided by the root of this tooth. The genetictheory assigns the eruption anomaly of the maxillarypermanent canine to a multifactorial complex thatcontrols the expression of other, possibly concurrent,tooth anomalies.18 Peck et al18 also found multipleevidential categories for the genetic origin of palatallydisplaced maxillary canines: familial occurrence, bilat-eral occurrence (17%-45%), sex differences (indicatinginvolvement of the sexual chromosomes), differencesin prevalence rates among different populations, andincreased occurrence of other concomitant dentalanomalies. Other studies have also added evidence tosupport the genetic theory as the explanation for pala-tally displaced canines.14,19
Most clinicians agree that the presence of the maxil-lary permanent canines in the dental arch is importantfor both esthetic and functional occlusion and shouldbe preserved whenever possible. In the case of impactedcanines, the orthodontist should make a maximum ef-fort to bring those teeth into alignment. However, insome situations when impaction of a maxillary perma-nent canine is severe, extraction might be a feasibleoption that satisfies the treatment goals for esthetics,function, and stability.3
From many reports of ectopic eruption and impac-tion of maxillary canines, it can be concluded thatcomplications such as root resorption of the maxillarypermanent incisors are common.11,12,20 Rootresorption of the maxillary incisors due to ectopiceruption of the canines can be observed as early as 10
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Fig 7. Expansion of the maxillary arch and initial retraction of the mandibular canines.
Fig 8. Orthodontic retraction of the mandibular incisors.
260 Garib et al
and 11 years of age.12 In periapical radiographs, rootresorption can be observed in approximately 12% ofthe incisors adjacent to ectopically erupting maxillarycanines.7 However, this prevalence is higher when theanalysis is performed by computed tomography, becauseit is much more sensitive than periapical radiographs.Studies have shown that root resorption of the maxillaryincisors in 48% of the patients with maxillary canineectopic eruption is observed in computed tomographyanalysis.11,20 This investigation confirmed previoussuggestions that root resorption caused by ectopiccanines occurs more often than is generally assumed.7
Although incisor root resorption caused by ectopicmaxillary canines can be silent and devastating, aneffective protocol has been developed for early detectionand management of this condition.12 Palpation andradiographic evaluation are combined with deciduouscanine removal in certain patients.9 A radiographic studyshowed that, in children older than 10 years, the inabilityto palpate the canine strongly indicates an eruptiondisturbance, which can be confirmed by supplementaryradiographic investigation.4 Early diagnosis showingthe location and full extent of resorption can be a criticalfactor in minimizing damage and serious long-termsequelae.12
In our patient, a previous panoramic radiographtaken in the mixed dentition had already indicated a pos-sible eruption disturbance of the maxillary left
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permanent canine (Fig 6). A slight superimposition ofthe maxillary canine crown with the lateral incisor rooton the left side indicated that the maxillary canine wouldhave an ectopic pathway of eruption.5 Once the possibleectopic pathway of eruption was diagnosed, treatmentshould have included deciduous canine extraction toprevent canine retention and maxillary incisor root re-sorption.21 If early intervention had been performed toprevent maxillary canine impaction, perhaps the maxil-lary incisor roots would not have been severely resorbed.
Interestingly, the maxillary left central incisor rootwas more resorbed than the maxillary left lateral incisoradjacent to the impacted teeth. However, previousreports have shown that the maxillary central incisorsare less commonly resorbed than are the maxillary lateralincisors.12,22
Due to the severe malpositon of the ectopic maxillaryleft canine, which was horizontally and mesially located,and the poor prognosis for orthodontic traction witha significant risk to accentuate the incisor root resorp-tion, we decided to extract the impacted tooth. Accord-ing to Kokich,23 certain impactions can be frustrating,and the esthetic outcome can be unpredictable.
The decision to extract the maxillary right canine wasbased on the goal for symmetry of the smile, mechanicalsimplification, and achievement of a pleasant smile andgingival esthetics. The maxillary right canine was labiallydisplaced, and the clinical crown had an increasedlength. The treatment option of maxillary right firstpremolar extraction could have led to an unfavorableincrease of the canine's clinical crown length, becauseof the initially small amount of gingiva.24 The unestheticsmile could have been related to the different clinicalcrown lengths.24 So, the maxillary right canine wasalso extracted to obtain anterior symmetry with bilateralpremolar substitutions. Extraction of both maxillarycanines provided, at the end of treatment, a symmetricaland harmonious smile and group function in lateralexcursions. It also allowed the application of symmetri-cal mechanics on both sides.
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Fig 9. Posttreatment facial and intraoral photographs.
Fig 10. Posttreatment cephalometric tracing.
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The patient had a slight Class III facial pattern witha retrognathic maxilla and a mild Class III malocclusion.Her acceptable facial esthetics and the severity of themalocclusion permitted a camouflage orthodontictreatment plan. In the mandible, the objectives were toextract the first premolars, align the teeth, and closethe spaces. The maxillary arch was expanded, and thetransverse relationship was corrected. The occlusalobjectives were to improve the intercuspation of theposterior teeth and promote satisfactory overbite andoverjet. The advantage of this treatment plan was tosimplify mechanics, avoiding maxillary incisor move-ment, which could increase the severity of rootresorption.
The final result showed a slight difference in thegingival margin levels of the maxillary right and leftcentral incisors (Fig 9); this was present in the initialmalocclusion (Fig 1). An option to level the gingivalmargins would be to intrude the maxillary right centralincisor followed by resin augmentation.24,25 However,
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Fig 11. Final orthodontic models.
Fig 12. Pretreatment and posttreatment lateral cephalometric tracings: A, superimposed overall (onSN, centered at S);B,maxillary (on palatal plane, centered at ANS); andC,mandibular (on mandibularplane, centered at Pog).
262 Garib et al
the severe root resorption contraindicated thisprocedure.
The severe incisor root resorption in this patientdid not contraindicate orthodontic treatment, sincewe used simplified mechanics, light forces, and
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careful follow-ups with periapical radiographs duringtreatment.
During orthodontic finishing, we wanted to avoidocclusal contacts on the maxillary incisor in centricocclusion to prevent further root resorption. In the
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Fig 13. Posttreatment panoramic radiograph.
Fig 14. Posttreatment periapical radiograph.
Garib et al 263
long term, even severely resorbed teeth do not showcontinuous resorption, increasing mobility, or discolor-ation, and might not require splinting.26
Although the maxillary incisor roots had severeresorption, especially the central incisors, there was nocontraindication for orthodontic treatment. The maxil-lary canines and the mandibular first premolars were ex-tracted, the spaces were closed, and favorable estheticsand excellent long-term occlusal results were obtained.
CONCLUSIONS
This patient highlights the importance of earlydiagnosis of maxillary canine ectopic eruption. Theidentification of early radiographic signs of an ectopicpathway of eruption should be followed by deciduouscanine extraction to prevent canine retention andmaxillary incisor root resorption.
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4. Ericson S, Kurol J. Radiographic assessment of maxillary canineeruption in children with clinical signs of eruption disturbance.Eur J Orthod 1986;8:133-40.
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16. Becker A, Smith P, Behar R. The incidence of anomalous maxillarylateral incisors in relation to palatally-displaced cuspids. AngleOrthod 1981;51:24-9.
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18. Peck S, Peck L, Kataja M. The palatally displaced canine as a dentalanomaly of genetic origin. Angle Orthod 1994;64:249-56.
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22. Knight H. Tooth resorption associated with the eruption ofmaxillary canines. Br J Orthod 1987;14:21-31.
23. KokichVG. Surgical and orthodonticmanagement of impactedmax-illary canines. Am J Orthod Dentofacial Orthop 2004;126:278-83.
24. Kokich VG, Nappen DL, Shapiro PA. Gingival contour and clinicalcrown length: their effect on the esthetic appearance of maxillaryanterior teeth. Am J Orthod 1984;86:89-94.
25. Kokich VG. Excellence in finishing: modifications for the perio-restorative patient. Semin Orthod 2003;9:184-203.
26. Becker A, Chaushu S. Long-term follow-up of severely resorbedmaxillary incisors after resolution of an etiologically associatedimpacted canine. Am J Orthod Dentofacial Orthop 2005;127:650-4.
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