Case of the month, AJODO 2011 July, case1

CASE REPORT

Adult Class II Division 1 patient with severegummy smile treated with temporary anchoragedevices

Rui Shu,a Lan Huang,b and Ding Baic

Sichuan and Chongqing, People's Republic of China

aPostgDeparversitbOrthogy, CcProfementChengThe aucts oReprinof Ort3rd see-maiSubm0889-Copyrdoi:10

A 23-year-old Mongolian woman came for a consultation with chief complaints of protrusive lips and a gummysmile. The clinical examination showed a convex profile, a protrusive maxilla, excessively proclined and ex-truded maxillary incisors, and a Class II Division 1 malocclusion. Temporary anchorage devices (TADs) in theposterior dental region were used as anchorage for the retraction and intrusion of her maxillary anterior teeth.Those appliances, combined with a compensatory curved maxillary archwire, eliminated the severe gummysmile and the protrusive profile, and corrected the molar relationship from Class II to Class I. With no extra tem-porary anchorage devices in the anterior region for intrusion, the treatment was workable and simple. The patientreceived a satisfactory occlusion and an attractive smile. (Am J Orthod Dentofacial Orthop 2011;140:97-105)

Temporary anchorage devices (TADs) have changedthe conventional conception of anchorage controland biomechanics in orthodontics. They have re-

placed many traditional types of mechanics and simpli-fied orthodontic treatment. In 1983, Creekmore andEklund1 reported a patient with a deep overbite cor-rected with a Vitallium bone screw; it was the first reportof the clinical use of TADs. Based upon the extensive ap-plications of TADs, many appliances have been inventedto solve orthodontic problems, such as a protrusive alve-olus and a significant gummy smile. Gummy smile refersto excessive gingival display during full smile. The cur-rent opinion is that less than 2 mm of gingival exposureis more esthetic and youthful.2-4 Kim et al5 and Kim andFreitas6 introduced a Class II Division 2 patient treatedwith a segmental arch appliance with TADs, which

raduate student and PhD candidate, State Key Laboratory of Oral Diseases,tment of Orthodontics, West China Stomatology Hospital of Sichuan Uni-y, Chengdu, Sichuan, People's Republic of China.odontist, Department of Orthodontics, The Affiliated Hospital of Stomatol-hongqing Medical University, Chongqing, People's Republic of China.ssor and department chair, State Key Laboratory of Oral Diseases, Depart-of Orthodontics, West China Stomatology Hospital of Sichuan University,du, Sichuan, People's Republic of China.uthors report no commercial, proprietary, or financial interest in the prod-r companies described in this article.t requests to: Ding Bai, State Key Laboratory of Oral Diseases, Departmenthodontics, West China Stomatology Hospital of Sichuan University, 14#,ction of Renmin South Road, Chengdu 610041, People’s Republic of China;l, [email protected], December 2010; revised and accepted, January 2011.5406/$36.00ight � 2011 by the American Association of Orthodontists..1016/j.ajodo.2011.01.021

corrected the excessive vertical growth of the maxillaryanterior dentoalveolar complex and alleviated thegummy smile. Lin et al7 reported on 4 patients withgummy smiles treated by a combination of TADs andperiodontal surgery without orthognathic surgery. Butthere has been no case report of TADs used in the treat-ment of a Class II Division 1 patient with a significantgummy smile.

In this case report, we aimed to introduce the treat-ment of a woman with a Class II Division 1 malocclusion.TADs with compensatory curved archwires corrected thepatient’s protrusive profile and significant gummy smile.

DIAGNOSIS AND ETIOLOGY

The patient, a 23-year-old Mongolian woman, hada convex profile and a Class II malocclusion. Her chiefcomplaints were protrusive lips and a gummy smile.

The photographs taken before treatment showedprotrusive upper and lower lips, both of which exceededthe E-line and were strained on closure (Fig 1). Noanomaly was seen in the frontal facial photos, exceptthat the patient was overly cautious about smiling nat-urally. When the patient relaxed, we took another smil-ing image (Fig 2), which showed a significant gummysmile with more than 4 mm of gingival exposure in theincisor region. The photographs and pretreatment studycasts (Fig 3) exhibited excessively proclined and extrudedmaxillary incisors, and cusp-to-cusp canine and molarrelationships with a deep overbite and overjet and no ap-parent crowding. The clinical examination suggested

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Fig 1. Pretreatment photographs.

Fig 2. Pretreatment smiling photographs.

98 Shu, Huang, and Bai

incisal and canine guidance without prematurity andshift. The patient had no temporomandibular jointsymptoms. No deviation and pain during the bordermovement of the mandible were discovered. No shortor hyperactive upper lip or vertical maxillary excess wasfound in our clinical examination that could be theetiology of the gummy smile.8-10

A cephalogram (Fig 4, A) and a panoramic radio-graph (Fig 4, C) were taken before treatment. The ceph-alometric analysis (Table) and the tracing (Fig 4, B)demonstrated a Class II skeletal relationship (ANB, 6�)as a result of the retruded mandible. The A-point wasin the normal range (SNA, 80�), and B-point was ret-ruded (SNB, 74�). The angle between the maxillary inci-sors and the S-N plane was 112�, and the IMPA was101�, which indicated that the protrusive profile wasmainly caused by the proclined maxillary anterior teeth.

TREATMENT OBJECTIVES

The treatment objectives were to create a satisfactoryocclusion with a Class I molar relationship and normalizeoverjet and overbite. Retraction and intrusion of themaxillary anterior teeth were indicated to reduce the ex-posure of the gingiva and the protrusive profile. Simul-taneously, extrusion of the posterior teeth would belimited to prevent a clockwise rotation of the mandibleand an increase in lower facial height.

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TREATMENT ALTERNATIVES

Three alternatives were presented to the patient.

1. Combined surgical and orthodontic treatment toharmonize the molar relationship with extractionof premolars in both the maxilla and the mandible.Orthognathic surgery could be used to elevate andretrude the anterior maxillary dentoalveolar part toeliminate the gummy smile and improve the profile.Advancement genioplasty could be used to camou-flage the retruded mandible and improve the profile.

Journal of Orthodontics and Dentofacial Orthopedics

Fig 3. Pretreatment study casts.

Shu, Huang, and Bai 99

2. Harmonize the molar relationship and retract theanterior teeth by extracting the maxillary first pre-molars and the mandibular second premolars. UseTADs to provide absolute anchorage for maximumretraction of the proclined maxillary teeth and max-illary incisor intrusion to eliminate the gummysmile. The disadvantage was that the retruded man-dible would not be corrected.

3. Extract the maxillary first premolars and the man-dibular second premolars, and use J-hook headgearas anchorage for retraction and intrusion. Thedisadvantage was that the effect of this treatmentdepended on the patient’s cooperation.

After we discussed these alternatives with the patient,she chose the second option. She considered theimprovement from orthognathic surgery not worth theadditional cost and risk, and the headgear wasunacceptable.

TREATMENT PROGRESS

Orthodontic treatment began on February 28, 2006,and lasted for 38 months. Before bracket bonding, themaxillary first premolars and mandibular second premo-lars were extracted. Two mini-implants (1.6 3 9 mm,Aarhus, Medicon, Tuttlingen, Germany) were placed

American Journal of Orthodontics and Dentofacial Orthoped

between the roots of the maxillary second premolarsand first molars, 3 mm occlusally to the buccal frenum.11

Preadjusted 0.022-in brackets (Shiye, Hangzhou,China) were bonded to all teeth. With sequentialnickel-titanium archwires, alignment and levelingwere achieved in 9 months. Then, 0.018 3 0.025-instainless steel wires were placed in both dental arches.The maxillary wire had a 5-mm compensating curve ofSpee. Nickel-titanium closed-coil springs and Class IIelastics were used for space closure and mesial mandib-ular molar movement (Fig 5, A). In the 20th month oftreatment, the mandibular space was closed, and thefirst molars were in a Class I relationship. Further max-illary retraction was achieved by nickel-titanium closedcoil springs on the TADs (Fig 5, B). After 4 months ofretraction of the maxilla, both overbite and overjetwere reduced. No Class II elastics were used duringthe final maxillary retraction. At the third stage, thesecond molars were bonded, and intermaxillary elasticswere applied with 0.018-in stainless steel wires in thebrackets for better interdigitation of the occlusion(Fig 5, C).

The total treatment time was 3 years 4 months. Ittook approximately 9 months to close the mandibularspace and over 20 months to retract and intrude themaxillary anterior teeth.

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Fig 4. A, Pretreatment cephalogram; B, cephalometric tracing; and C, panoramic radiograph.

Table. Cephalometric data

Norm Pretreatment Posttreatment D

SNA (�) 83.13 6 3.6 80 79 �1SNB (�) 79.65 6 3.2 74 74 0ANB (�) 3.48 6 1.69 6 5 �1FMA (�) 29 6 5 34 36 2U1 to SN (�) 102 6 5.4 112 99 �13IMPA (�) 97 6 6 101 92 �9Interincisalangle (�)

126.96 6 8.54 105 124 19


TREATMENT RESULTS

The posttreatment photographs (Fig 6) showed a re-markable improvement in lip profile from the significantretraction of the anterior teeth. Meanwhile, there was nogummy smile at the posttreatment clinical examination.The posttreatment photographs (Fig 6) and dental casts(Fig 7) demonstrated Class I canine and molar relation-ships with normal overbite and overjet. The posttreat-ment cephalogram and panoramic radiograph areshown in Figure 8. The cephalometric analysis (Table)and superimposition (Fig 8, B) showed no change inthe position of the maxillary molars. The incisal edgeof the maxillary incisors was retracted by 7 mm and in-truded by 2.5 mm, and the mandibular first molarsmoved 3.5 mm mesially. Normal overbite and overjetwere achieved. The maxillary anterior alveolar boneand gingiva moved lingually and upward with the toothmovement. However, the final cephalometric analysis(Table) showed that the skeletal discrepancy betweenthe maxilla and the mandible remained unchanged.The comparison between the pretreatment and post-treatment panoramic radiographs showed no apparentroot shortening.


DISCUSSION

Gummy smiles can be classified by etiology into soft-tissue,3 dentoalveolar, and skeletal types.6,8-10 Theskeletal type is caused by excessive vertical maxillarygrowth and is found in patients with long-face syn-drome. Orthognathic surgery is generally required totreat this problem.8,12 However, in some dentoalveolarcases, orthognathic surgery could produce anunfavorable result. For the patient whose gummy smileis derived from protrusion and extrusion of themaxillary anterior dentoalveolar complex, decreasedanterior dentoalveolar height after surgery might result


Fig 5. Treatment progress: A, combination of nickel-titanium closed-coil springs and Class II elastics;B, nickel-titanium closed coil springs on the TADs for further maxillary retraction; and C, intermaxillaryelastics for better occlusion.


in a low smile.13 These considerations, plus the favorableoutcome of the selected treatment, suggested that or-thognathic surgery was inappropriate for eliminatingthe gummy smile in our patient. In addition, the patientthought that improvement of her profile was not worththe additional cost and risk. As a result, orthognathicsurgery was abandoned after careful consideration.

Two mandibular second premolars were extracted in-stead of 2 mandibular first premolars, because mandib-ular first premolar extractions might increase thedifficulty of mesial movement of the mandibular molars.The selected alternative, extraction of the maxillary firstpremolars and mandibular second premolars, whichameliorated the profile andmolar relationship, is a classictreatment modality for a Class II Division 1 patient.

For this patient, the convex profile and gummy smilewere both caused by excessive protrusion of the maxil-lary anterior dentoalveolar complex. Thus, maximum re-traction of the maxillary anterior teeth was needed. Tomeet this purpose, anchorage control was emphasizedthroughout the treatment.


Before the development and application of TADs, or-thodontists’ choices were limited to appliances such astranspalatal arches, Nance arches, and headgears.14

These appliances have disadvantages, such as their unes-thetic appearance, undesirable intermittent forces, anddependence on patient cooperation. Also, mesial move-ment of the molars was inevitable even with these appli-ances. Correction of gummy smiles with continuouslight intrusion forces on the maxillary anterior dentalarch3,15 could be accomplished by extraoral intrusionappliances such as headgear16 and J-hook.17 Traditionalintrusion techniques, such as utility arches18 and 1-pieceintrusion arches,19 were not optimal for this patient, be-cause they require anchorage on the molars and produceundesirable moments on the anterior teeth.

The first clinical case report about TADS was pub-lished in 1983. Creekmore and Eklund1 used a Vitalliumbone screw in treating a patient with a deep overbite.But TADs were not accepted immediately. TADs havegradually become more acceptable and are now usedin solving orthodontic problems. Currently, several cases


Fig 6. Posttreatment photographs.

Fig 7. Posttreatment study casts.


July 2011 � Vol 140 � Issue 1 American Journal of Orthodontics and Dentofacial Orthopedics

Fig 8. A, Posttreatment cephalogram; B, superimposition; and C, panoramic radiograph.


have been reported in the literature with TADs for en-masse retraction. With time, TADs are gradually replac-ing the aforementioned appliances and have becomethe preferred anchorage option for orthodontists.

The development of TADs has triggered various noveltechniques for treating gummy smiles. Kim et al5 intro-duced a segmental archwire assisted by placing TADs be-tween the roots of the maxillary central incisors tocorrect a gummy smile that was caused by verticalgrowth of the maxillary anterior dentoalveolar complex.Lin et al7 reported on 4 patients with skeletal gummysmiles treated with a combination of TADs and peri-odontal surgery. But there have been no reports of a ClassII Division 1 patient with a gummy smile treated withTADs.

For Class II Division 2 patients, TADs in the anterioralveolus could provide an intrusion force and procliningmoments on the maxillary incisors; this is ideal for ex-truded and retruded teeth. But in our Class II Division1 patient, the gummy smile was caused by protrusionand excessive vertical growth of the anterior dentoalveo-lar complex. Therefore the mechanical system for Class IIDivision 1 patients should be different. TADs in the


anterior alveolus were not appropriate. We adoptedTADs between the maxillary second premolars and firstmolars combined with nickel-titanium closed-coilsprings that could provide a continuous total force pass-ing near the center of resistance of the 6 anteriorteeth.16,20-23 The force could be divided into 2 parts:a greater horizontal force for retraction of theprotrusive anterior dentoalveolar complex anda smaller vertical force for intrusion of the anteriorteeth (Fig 9, A).

The smaller vertical force was suitable and enough tomeet the need for anterior tooth intrusion. This appli-ance is simple and workable in the treatment of patientswith gummy smiles and Class II Division 1 malocclusion.On the other hand, this mechanical system is also sug-gested for the Class II Division 1 patient who has a lowor average smile.13 However, the intrusion force pro-duced by TADs during en-masse retraction will reducethe exposure of the maxillary teeth, and this wouldaggravate an unesthetic smile.

However, orthodontists have found that the TADstechnique could not completely eliminate anchorageloss. One reason is that the force on the traction hook


Fig 9. Mechanical analysis. A, Force system involved: F, total force; V, vertical force; H, horizontalforce (H was much greater than V ); CR, center of resistance. B, Couples induced by deformation ofthe archwire.


will cause deformation even with stainless steel archwires;it also creates couples, inducing mesial tipping of the mo-lars and lingual tipping of the anterior teeth (Fig 9, B).A finite element analysis of TADs used for en-masse re-traction also showed that the inclination of the incisorwould be reduced without torque control even when thetotal force passed through the center of resistance of the6 anterior teeth.24 To ensure maximal retraction and pre-vent excessive lingual tipping of the anterior teeth, weplaced a compensatory curve in the maxillary archwire,which could counteract the deformation of archwire,provide torque control on the anterior teeth, and assistin correcting the deep overbite. Torque control of the an-terior teeth also prevented the roots from approximatingthe cortical plate, which, when combined with continuouslight retraction forces, effectively reduced root resorp-tion.3,25 The posttreatment radiographs might have


underestimated root resorption but did not show anyapparent root shortening.26 The treatment with ourappliance produced a satisfactory outcome.

CONCLUSIONS

TADs and a curved archwire were adopted for thetreatment of a 23-year-old woman with protrusive lipsand a gummy smile, and a desirable result was achieved.

1. The protrusive anterior dentoalveolar complex andexcessively erupted anterior teeth were correctedby retraction and intrusion of the anterior dental al-veolus; this eliminated the gummy smile and theprotrusive profile.

2. For intrusion of the maxillary anterior teeth in ClassII Division 1 patients, posterior TADs provide moreoptimal force than TADs placed in the anterior part.



3. When TADs are used for en-masse retraction ina Class II Division 1 patient with a low smile, aggra-vation of the unesthetic smile is caused by an intru-sion force from the TADs and should be avoided.

4. The appropriate application of TADs to correcta gummy smile must be based on the correct anal-ysis of the etiology.

5. The compensatory curve played an important role inanchorage control of the molars, torque control ofthe anterior teeth, and correction of the deep over-bite.

6. This appliance was simple and workable for thetreatment of a Class II Division 1 patient witha gummy smile, and she was satisfied with the result.

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