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Substitution of impacted canines by maxillary rst premolars: A valid alternative to traditional orthodontic treatment Davide Mirabella, a Gabriella Giunta, b and Luca Lombardo c Ferrara and Verona, Italy A 13-year-old girl came with the chief complaint of an unesthetic dental appearance. Her maxillary canines were bilaterally impacted. Treatment included extraction of the maxillary canines and the mandibular second premo- lars. The maxillary rst premolars were substituted for the canines. After 26 months of active treatment, the pa- tient had a Class I molar relationship and ideal overbite and overjet. Her prole was improved, lips were competent, and gingival levels were acceptable. Cephalometric evaluation showed acceptable maxillary and mandibular incisor inclinations. Intraoral pictures taken 3 years 7 months after the end of treatment demonstrated that the extraction of impacted canines and their substitution by rst premolars can be a valid alternative to tra- ditional orthodontic treatment when maxillary premolar extraction is a treatment option. (Am J Orthod Dentofacial Orthop 2013;143:125-33) T he prevalence of impacted canines has been re- ported to be from 0.2% to 2.8%, and it is signi- cantly higher in female subjects than in males (male:female ratio, 51:3). 1,2 In most patients, the impacted canines are ectopically positioned. Eighty-ve percent are palatal to the dental arch. 3-5 However, in a recent study of 156 ectopically positioned canines, 50% were in a palatal or distopalatal position, 39% in a buccal or distobuccal position, and 11% apical to the adjacent incisor or between the roots of the central and lateral incisors. 6 Var- ious etiologic factors have been implicated for impacted maxillary canines: eg, ectopic position of the tooth germ, lack of space, lack of guidance, and genetic factors. 4,7,8 Maxillary canines play an important role in creating good facial and smile esthetics, since they are positioned at the corners of the dental arch, forming the canine em- inence for support of the alar base and the upper lip. Fur- thermore, when the maxillary canines are properly aligned and have good shape and size, pleasing anterior dental proportions and correct smile lines are achieved. Func- tionally, they support the dentition, contributing to disar- ticulation during lateral movements in certain persons. Impacted canines can be successfully aligned in the arches by a combined orthodontic-surgical approach, and several treatment strategies have been proposed. Such complex therapeutic management should be con- sidered successful if the impacted canine is properly aligned in the dental arch with a healthy periodon- tium. 9,10 However, some adverse effects related to the orthodontic extrusion of an impacted canine have been described in the literature. Differences in tooth color, alignment, vitality, probing pocket depth, and crestal bone and gingival margin heights have been reported between the previously impacted canine and its contralateral tooth. Furthermore, apical root resorption and loss of hard and soft periodontal tissues have been observed in teeth adjacent to the extruded canine. 11 Although the treatment of choice for an impacted ca- nine is a combined surgical-orthodontic approach, an alternative treatment in a patient with bilateral palatally impacted canines is presented. DIAGNOSIS AND ETIOLOGY A 13-year-old girl came with the chief complaint of an unesthetic dental appearance (Figs 1-4). The facial analysis showed a mandibular retrognathic prole, incompetent lips, perioral muscular strain, and a slightly protrusive dentition upon smiling. The intraoral examination showed a healthy periodontium, a Visiting professor, University of Ferrara, Ferrara, Italy; private practice, Catania, Sicily, Italy. b Private practice, Verona, Italy. c Research assistant, Department of Orthodontics, University of Ferrara, Ferrara, Italy. The authors report no commercial, proprietary, or nancial interest in the prod- ucts or companies described in this article. Reprint requests to: Davide Mirabella, Via Vagliasindi, 53, 95125 Catania, Italy; e-mail, [email protected]. Submitted, July 2011; revised and accepted, August 2011. 0889-5406/$36.00 Copyright Ó 2013 by the American Association of Orthodontists. http://dx.doi.org/10.1016/j.ajodo.2011.08.029 125 CASE REPORT
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Page 1: Substitution of impacted canines by maxillary first ... · maxillary and mandibular right second premolars, and maxillary second molars. The panoramic radiograph showed bilateral

CASE REPORT

Substitution of impacted canines by maxillaryfirst premolars: A valid alternative to traditionalorthodontic treatment

Davide Mirabella,a Gabriella Giunta,b and Luca Lombardoc

Ferrara and Verona, Italy

aVisitiSicily,bPrivacReseItaly.The aucts oReprine-maiSubm0889-Copyrhttp:/

A 13-year-old girl came with the chief complaint of an unesthetic dental appearance. Her maxillary canines werebilaterally impacted. Treatment included extraction of the maxillary canines and the mandibular second premo-lars. The maxillary first premolars were substituted for the canines. After 26 months of active treatment, the pa-tient had a Class I molar relationship and ideal overbite and overjet. Her profile was improved, lips werecompetent, and gingival levels were acceptable. Cephalometric evaluation showed acceptable maxillary andmandibular incisor inclinations. Intraoral pictures taken 3 years 7months after the end of treatment demonstratedthat the extraction of impacted canines and their substitution by first premolars can be a valid alternative to tra-ditional orthodontic treatment whenmaxillary premolar extraction is a treatment option. (Am JOrthod DentofacialOrthop 2013;143:125-33)

The prevalence of impacted canines has been re-ported to be from 0.2% to 2.8%, and it is signifi-cantly higher in female subjects than in males

(male:female ratio, 51:3).1,2

In most patients, the impacted canines are ectopicallypositioned. Eighty-five percent are palatal to the dentalarch.3-5 However, in a recent study of 156 ectopicallypositioned canines, 50% were in a palatal ordistopalatal position, 39% in a buccal or distobuccalposition, and 11% apical to the adjacent incisor orbetween the roots of the central and lateral incisors.6 Var-ious etiologic factors have been implicated for impactedmaxillary canines: eg, ectopic position of the tooth germ,lack of space, lack of guidance, and genetic factors.4,7,8

Maxillary canines play an important role in creatinggood facial and smile esthetics, since they are positionedat the corners of the dental arch, forming the canine em-inence for support of the alar base and the upper lip. Fur-thermore,when themaxillary canines are properly alignedand have good shape and size, pleasing anterior dental

ng professor, University of Ferrara, Ferrara, Italy; private practice, Catania,Italy.te practice, Verona, Italy.arch assistant, Department of Orthodontics, University of Ferrara, Ferrara,

uthors report no commercial, proprietary, or financial interest in the prod-r companies described in this article.t requests to: Davide Mirabella, Via Vagliasindi, 53, 95125 Catania, Italy;l, [email protected], July 2011; revised and accepted, August 2011.5406/$36.00ight � 2013 by the American Association of Orthodontists./dx.doi.org/10.1016/j.ajodo.2011.08.029

proportions and correct smile lines are achieved. Func-tionally, they support the dentition, contributing to disar-ticulation during lateral movements in certain persons.

Impacted canines can be successfully aligned in thearches by a combined orthodontic-surgical approach,and several treatment strategies have been proposed.Such complex therapeutic management should be con-sidered successful if the impacted canine is properlyaligned in the dental arch with a healthy periodon-tium.9,10 However, some adverse effects related to theorthodontic extrusion of an impacted canine have beendescribed in the literature. Differences in tooth color,alignment, vitality, probing pocket depth, and crestalbone and gingival margin heights have been reportedbetween the previously impacted canine and itscontralateral tooth. Furthermore, apical root resorptionand loss of hard and soft periodontal tissues have beenobserved in teeth adjacent to the extruded canine.11

Although the treatment of choice for an impacted ca-nine is a combined surgical-orthodontic approach, analternative treatment in a patient with bilateral palatallyimpacted canines is presented.

DIAGNOSIS AND ETIOLOGY

A 13-year-old girl came with the chief complaint ofan unesthetic dental appearance (Figs 1-4). The facialanalysis showed a mandibular retrognathic profile,incompetent lips, perioral muscular strain, anda slightly protrusive dentition upon smiling. Theintraoral examination showed a healthy periodontium,

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Fig 1. Pretreatment photographs.

126 Mirabella, Giunta, and Lombardo

mild maxillary transverse constriction, and moderatecrowding in the maxillary and mandibular arches. AClass I molar relationship was present, and all teethwere erupted except for the maxillary canines,maxillary and mandibular right second premolars, andmaxillary second molars. The panoramic radiographshowed bilateral maxillary canine impaction. The rightcanine was high with respect to the occlusal plane andhorizontally oriented. Lack of spaces for second andthird molar eruption in the mandibular arch was alsonoticeable. The cephalometric analysis showed anacceptable vertical and anteroposterior skeletalrelationship, with moderate proclination of themaxillary and mandibular incisors (Table). A familial his-tory of maxillary impacted canines suggested that theetiology of this malocclusion could be partially genetic.

TREATMENT OBJECTIVES

The treatment objectives were to maintain a Class Idental relationship, align the maxillary and mandibular

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dental arches, provide adequate space for the surgicalextrusion of the maxillary canines, improve lip compe-tence, and reduce dentoalveolar protrusion duringsmiling.

TREATMENT ALTERNATIVES

Nonextraction and extraction plans were considered.The maxillary and mandibular dental arches could

have been aligned and leveled without the extractionof any permanent teeth by means of interproximalenamel reduction and dentoalveolar expansion. Afterthe creation of adequate space, the maxillary caninescould have been erupted by a combined orthodontic-surgical approach. However, because of the crowding,the dentoalveolar biprotrusion, and the incompetentlips, this treatment plan could have led to a more severedentoalveolar biprotrusion and would not have ad-dressed lip incompetence. In addition, excessive incisorproclination could have had a questionable effect onlong-term stability.

Journal of Orthodontics and Dentofacial Orthopedics

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Fig 3. Pretreatment panoramic radiograph.

Fig 4. Pretreatment lateral headfilm and tracing.

Fig 2. Pretreatment dental casts.

Mirabella, Giunta, and Lombardo 127

Crowding associated with dentoalveolar biprotrusionis efficiently corrected by maxillary and mandibular firstpremolar extractions. In this patient, premolar extrac-tions would have also addressed lip incompetence andcreated space for easier extrusion of the impacted ca-nines. The anchorage could be provided by a palatalminiscrew because the bone shape was suitable.12 How-ever, a long treatment time could have been required,and the risks related to orthodontic extrusion ofimpacted canines could not have been ruled out. In ad-dition, because of the highly unfavorable maxillary leftcanine position, successful extrusion of this tooth wouldnot have been ensured.

An alternative orthodontic treatment plan requiredmaxillary and mandibular second premolar extractions.It would have allowed aligning and leveling of the

American Journal of Orthodontics and Dentofacial Orthoped

arches, reduction of the dentoalveolar biprotrusion,and an improved facial appearance. In addition, man-dibular second premolar extractions (compared with firstpremolar extractions) might have reduced the amount ofincisor retraction during space closure, resulted in lessflattening of the profile, and provided more space foreasier molar eruption.

The treatment plan selected included surgical extrac-tion of the maxillary impacted canines and the mandib-ular second premolars; the maxillary first premolars

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Table. Cephalometric measurements

Measurement Pretreatment PosttreatmentHorizontal skeletalSNA (�) 88.4 84.3SNB (�) 85.4 78.3ANB (�) 3.0 6.0Maxillary skeletal(A-Na perp) (mm)

2.7 7.6

Mandibular skeletal(Pg-Na perp) (mm)

�0.3 4.2

Wits (mm) �5.1 1.6Vertical skeletalFMA (MP-FH) (�) 22.8 17.3MP-SN (�) 27.5 30.5Palatal-mandibular angle (�) 25.1 20.5Palatal-occlusal plane (�) 12.9 9.0Mandibular plane toocclusal plane (�)

12.1 11.6

Anterior dentalMaxillary incisorprotrusion (mm)

9.7 1.6

Mandibular incisorprotrusion (mm)

5.9 �2.2

U1-PP (�) 114.9 107.1U1-occlusal plane (�) 52.1 64.0L1-occlusal plane (�) 71.1 80.5IMPA (�) 96.7 87.9

128 Mirabella, Giunta, and Lombardo

would replace the canines. This option allowed us to re-duce treatment time, improve the facial profile and lipcompetence, and achieve alignment and leveling of thearches without incisor proclination.

TREATMENT PROGRESS

After extraction of the maxillary canines and themandibular second premolars, preadjusted fixed appli-ances were placed, and alignment in the maxillary andmandibular dental arches was achieved by a 0.016-inthermal nickel-titanium wire. In the mandibular arch,the space closure started with lacebacks on the rightand left sides (Fig 5). Then, leveling was obtained inboth arches with 0.019 3 0.025-in thermal nickel-titanium wires. Maxillary and mandibular 0.019 30.025-in stainless steel rectangular archwires and powerchain were used to close the extraction spaces (Fig 6).The finishing stage of treatment was started, and a prog-ress panoramic radiograph (Fig 7) was taken to check forroot parallelism and topography of the extraction sites.Finishing bends were placed to correct any abnormalroot position and achieve marginal ridge leveling. Max-illary lateral incisor crown width was enlarged at the endof orthodontic treatment with composite buildup.

TREATMENT RESULTS

After 26 months of active treatment, the patient hada Class I molar relationship and ideal overbite and

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overjet. The profile was improved, the lips were compe-tent, and the cephalometric evaluation showed accept-able maxillary and mandibular incisor inclinations. Thefinal panoramic radiograph showed that good root par-allelism was achieved in the anterior regions as well asacross the extraction sites. The tracing superimpositionshowed mesial movement of the maxillary and mandib-ular first molars, and moderate distal movement andretroclination of the maxillary and mandibular incisors.The gingival levels were acceptable, but a slightlyhigher position of the maxillary premolars and gingivalmargin with respect to the maxillary lateral incisorsshould have been achieved. The smile looked natural,and the crown anatomy of the maxillary first premolarsand the accurate detailing of the incisors and the pre-molar positions helped in that respect (Figs 8-12,Table).

Maxillary circumferential and mandibular Hawleyretainers were delivered. Intraoral pictures taken 3 years7 months after the end of treatment show a pleasantsmile. The smile line looks almost ideal (Figs 13 and14). Oral hygiene is fair, with marginal gingivitis, butthe attached gingivae are within normal limits. Gingivallevels are clinically acceptable. Arch form and dentalalignment are good. The patient has a Class I molarand canine occlusion, and overjet and overbite are stillwithin normal limits. No temporomandibular joint ormuscle problems developed during the retention andpostretention periods. The temporomandibular jointsshow no clicking on opening and closing. Maximumopening of the jaws is normal, and no deviation uponopening was found. The masticatory muscles are silent.No mandibular shift was assessed upon closing, nor arepremature contacts evident. Incisor and canine guid-ances are present.

DISCUSSION

Treatment of impacted canines is a clinical challenge,because it is an interdisciplinary therapeutic approachthat involves both orthodontic and surgical procedures.The outcome of treatment of impacted canines is suc-cessful when the tooth is in a stable position and thedental arch has a healthy periodontium.13

However, an orthodontic-surgical approach can re-sult in several complications such as displacement andloss of vitality of the adjacent incisors, canine ankylosisor loss of vitality, recurrent pain, internal resorption, cys-tic degeneration, external root resorption of the canineand adjacent teeth, loss of periodontal bone support,or combinations of these factors.11 The external resorp-tion of the adjacent teeth is a major concern, and thismost common sequela of impacted canine treatmentcan result in tooth loss.14 Ericson and Kurol,6 in

Journal of Orthodontics and Dentofacial Orthopedics

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Fig 5. Progress intraoral photographs: leveling and aligning.

Fig 6. Progress intraoral photographs: closing the extraction spaces.

Fig 7. Progress panoramic radiograph.

Mirabella, Giunta, and Lombardo 129

American Journal of Orthodontics and Dentofacial Orthoped

a computed tomography study of 156 ectopically im-pacted maxillary canines, claimed that the percentageof lateral resorption described was 38%, lower thanthe reported percentage of 66.7% by Walker et al.15

In the long-term results of the orthodontic-surgicalapproach for treatment of impacted maxillary canines,D'Amico et al16 reported the procedure's side effects ob-served in a sample of 61 patients: 6.5% of the patientswere dissatisfied with the esthetic results, whereas theorthodontist who clinically evaluated the patients foundgood results in only 57% of them. The same authorsfound that the inclination of the previously impacted ca-nines was significantly different from that of the

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Fig 8. Posttreatment photographs.

130 Mirabella, Giunta, and Lombardo

normally erupted canines, leading to a less frequent ca-nine guidance on the working side during lateral move-ments of the mandible.

Data from the literature confirm the clinical experi-ence that the combined orthodontic-surgical treatmentis associated with several risk factors. Accordingly,a treatment alternative to eliminate these risks couldbe to extract the impacted tooth and treat the patientas an extraction case. Surgical extraction of the maxillaryimpacted canines eliminated all the risk factors and un-certainty related to orthodontic extrusion of an im-pacted canine. As Thoraton17 stated, there is noscientific evidence that 1 occlusal scheme is superior tothe other. In that respect, canine guidance can well besupplied by premolar guidance or a group function,since the maxillary first premolar is aligned slightly ex-truded with respect to its normal position.

Another possible clinical concern related to maxillarypremolar substitution is smile esthetics. The maxillaryfirst premolar is a shorter tooth than the maxillary ca-nine, thus leading to possible vertical position differ-ences in gingival levels or occlusal margins,

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depending on the final vertical position of the premo-lars. In case of space closure and canine substitutionin congenitally missing lateral incisor patients, Rosaand Zachrisson18 recommended intruding the first pre-molars to level the gingival margins and restoring thepremolars with composite resin buildups or porcelainveneers to resemble natural canines and produce a bal-anced smile. In this patient, canine guidance was ob-tained by slightly extruding the maxillary firstpremolars. It was decided to accept a slight vertical gin-gival level discrepancy, and neither crown lengtheningsurgical procedures nor restorative buildups were per-formed. This conservative approach was possible be-cause the maxillary first premolar crowns were long,with prominent buccal cusps and adequate mesiodistalwidths. In addition, a slight negative crown torque wasintroduced in the finishing stage to produce a naturalaspect as similar as possible to a maxillary canine. Alter-natively, intrusion of the maxillary first premolarswould have leveled the gingival margins, but lateral dis-clusion could have been lost, and a buildup restorationwould have been needed.

Journal of Orthodontics and Dentofacial Orthopedics

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Fig 9. Posttreatment dental casts.

Fig 10. Posttreatment panoramic radiograph.

Fig 11. Posttreatment lateral headfilm and tracing.

Mirabella, Giunta, and Lombardo 131

We decided to extract the mandibular second premo-lars to have 2 main clinical advantages: to reduce theamount of mandibular incisor retraction during spaceclosure, and to increase the amount of space for themandibular second molars. However, mandibular sec-ond premolar extraction can have 2 main disadvantages:(1) the interproximal contact point between the mandib-ular first molar and the first premolar might not fit prop-erly because mandibular first premolar anatomy oftenresembles canine anatomy rather than that of the man-dibular second premolar; and (2) after mandibular sec-ond premolar extraction, the mandibular first molarmight encounter an obstacle in sliding mesially intoa narrower alveolar ridge that results in difficult spaceclosure. This patient's mandibular first premolar anat-omy was carefully evaluated, and the mandibular first

American Journal of Orthodontics and Dentofacial Orthoped

premolars were judged to have good shape (quite flat in-terproximal surfaces) and size. Therefore, final mandib-ular posterior interproximal contact points wereclinically acceptable, and the adequate postextractionalveolar ridge thickness allowed for uncomplicated man-dibular first molar mesial movement.

CONCLUSIONS

The surgical extraction of impacted canines and theirsubstitution by first premolars could be a valid

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Fig 14. Photographs 3 years 7 months after the end of treatment.

Fig 12. Superimposed tracings.

Fig 13. Intraoral photographs 3 years 7 months after the end of treatment.

132 Mirabella, Giunta, and Lombardo

alternative to traditional orthodontic treatment whenmaxillary premolar extraction is a treatment option.This treatment alternative is a valuable option that elim-inates the risks associated with orthodontic-surgical

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treatment of impacted canines. Good functional and es-thetic results can be achieved, if an accurate and detailedanterior tooth position is managed during orthodonticfinishing.

Journal of Orthodontics and Dentofacial Orthopedics

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Mirabella, Giunta, and Lombardo 133

REFERENCES

1. Peck S, Peck L, Kataja M. The palatally displaced canine asa dental anomaly of genetic origin. Angle Orthod 1994;64:249-56.

2. Baccetti T. A controlled study of associated dental anomalies. An-gle Orthod 1998;68:267-74.

3. Rayne J. The unerupted maxillary canine. Dent Pract 1969;19:194-204.

4. Jacoby H. The etiology of maxillary canine impactions. Am JOrthod 1983;84:125-32.

5. Ericson S, Kurol J. Radiographic examination of ectopically erupt-ing maxillary canines. Am J Orthod Dentofacial Orthop 1987;91:483-92.

6. Ericson S, Kurol J. Resorption of incisors after ectopic eruptionof maxillary canines. A CT study. Angle Orthod 2000;70:415-23.

7. Becker A. Palatally impacted canines. In: Becker A, editor. The or-thodontic treatment of impacted teeth. London, United Kingdom:Martin Dunitz; 1998. p. 86.

8. Kurol J, Ericson S, Andreason JO. The impacted maxillary canine.In: Andreasen JO, Petersson JK, Laskin DM, editors. Textbookand color atlas of tooth impactions. Copenhagen, Denmark:Munksgaard; 1997. p. 129-30.

9. Hall WH. Recent status of soft tissue grafting. J Periodontol 1977;48:587-97.

10. Crescini A, Nieri M, Buti J, Baccetti T, Mauro S, Pini Prato GP.Short- and long-term periodontal evaluation of impacted canines

American Journal of Orthodontics and Dentofacial Orthoped

treated with a closed surgical-orthodontic approach. J Clin Perio-dontol 2007;34:232-42.

11. Woloshyn H,�Artun J, Kennedy DB, Joondeph DR. Pulpal and peri-odontal reactions to orthodontic alignment of palatally impactedcanines. Angle Orthod 1994;64:257-64:Erratum in Angle Orthod1994;64:324.

12. Lombardo L, Gracco A, Zampini F, Stefanoni F, Mollica F. Optimalpalatal configuration for miniscrew applications. Angle Orthod2010;80:145-52.

13. Nieri M, Crescini A, Rotundo R, Baccetti T, Cortellini P, PiniPrato GP. Factors affecting the clinical approach to impactedmaxillary canines: a Bayesian network analysis. Am J OrthodDentofacial Orthop 2010;137:755-62.

14. Jacobs R, Lambrechts P, Loozen G, Willems G. Root resorption ofthe maxillary lateral incisor caused by impacted canine: a literaturereview. Clin Oral Invest 2009;13:247-55.

15. Walker L, Enciso R, Mah J. Three-dimensional localization of max-illary canines with cone-beam computed tomography. Am JOrthod Dentofacial Orthop 2005;128:418-23.

16. D'Amico RM, Bjerklin K, Kurol J, Falahat B. Long-term results oforthodontic treatment of impacted maxillary canines. AngleOrthod 2003;73:231-8.

17. Thoraton L. Anterior guidance: group function/canine guidance. Aliterature review. J Prosthet Dent 1990;64:479-82.

18. Rosa M, Zachrisson B. Integrating space closure and estheticdentistry in patients with missing maxillary lateral incisors. J ClinOrthod 2007;41:563-73.

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