Treatment of overjet by retraction of frontal teeth to temporary anchorage devices (TADs)

Increased overjet may be caused by excessive proclination of upper incisors with prominent maxilla or on the other hand by microgenia or mandibular retrognathism. The first malocclusion is in adult patients usually corrected by extraction of first premolars and successive retraction of frontal teeth. The second malocclusion in adult patients is correctly treated with orthognathic surgery.
When treating with retraction of frontal teeth, it is essential to assess the amount of anchorage needed. If the movement of distal teeth mesially is restricted, the absolute anchorage secured by TADs is needed. TADs are placed into the bone in the right position. Closed coil springs are placed inbetween the frontal segment and TADs on each side, thus retracting frontal segment without any movement of posterior teeth.

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Anamnesis:

25 year old woman enquired about possibilities of orthodontic treatment for enhancing her facial and smile esthetics.
Chief complaint: „Big overjet, crooked lower teeth, ugly smile“
Medical history: Fit and well, overcome routine child diseases, smokes cigaretes
History of allergies: none
Medication: none
Dental: permanent dentition, carious; DMF=9; retentio d.48, d.38 extracted in past.
Orthodontic: no previous treatment

Examinations:

Extra-oral examination: mesocephalic, round symmetric face, pupils equally round, pupillary line horizontal, incompetent lips with average tonicity, profound mentolabial groove.

Smile analysis: asymmetric, gummy smile not present, display of half of the crowns of upper incisors, incisal edges don’t copy the lip line.

Examination of TMJ: Maximum mouth opening - 42mm, no displacement or deviation on closure, without pain, pathological sounds and path of closure.

Intra-oral examination: Average oral hygiene, average cariosity, pink gingiva, oral mucous membrane with no pathological signs, good periodontal condition, upper labial frenulum inserts to the incisive papilla.

Cast analysis: Permanent dentition, AII/1, overjet=10mm, overbite=-1mm, midline shift, crowding in the lower dental arch, space discrepancy in maxilla -1mm, in mandible -7mm, anterior Bolton ratio - 78.3%, overall Bolton ratio - 91.6%, Tonn‘s index - 77%, McNamara analysis - 35mm.

Imaging methods:

Cephalometric analysis before therapy: SNA: 79°, SNB: 73°, SNPo: 75°, ANB: 6°, Wits: 9mm, NS-ML: 35°, S-Go:N-Me: 63%, Mx 1-NS: 110°, Mx 1-NPo: 12mm, Interincisal: 118°, Mn 1-ML: 97°, Mn 1-Apo: -1mm, Beta: 21°.

Diagnosis:

AII/1; Overjet: 10mm; Overbite: -1mm; Class II skeletal base; Average growth pattern; Crowding of lower frontal teeth; Proclination of upper frontal teeth; Upper labial frenulum inserts to the incisive papilla; Lingual dystopic 32; Lingually inclined 35; Mesially rotated 41 and 42

Therapy:

Treatment objectives:
1. Extraction of 14, 24
2. Level and align upper and lower dental arch
3. Apply TADs and by bodily movement retract upper frontal segment
4. Relevelling
5. Frenectomy
6. Retention (ESSIX)

Treatment plan and appliances:
Preadjusted edgewise appliance – slot .022, prescription Roth, ceramic brackets Clarity Advanced
Orthodontic bands 16, 26, orthodontic tubes 36, 46
Orthodontic brackets 15-25, 35-45
TAD inbetween 16-15, 26-25 (6mm, 3M UNITEK)
Plan of occlusion - AII

Maxilla:
1. Levelling and aligning (NiTi .016)
2. .017x.025 NiTi
3. .017x.025 SS in the range of 13-23 with crimpable hooks, TAD inbetween 16-15 a 26-25, closed coil springs from the hooks to TADs
4. .020x.020 NiTi to relevel
5. Retention (ESSIX)

Mandible:
1. .014 NiTi
2. .016 SS, distalizing open coil spring 31-33 to enlarge the space for 32 – align with overlay .014 NiTi
3. .020x.020 NiTi
4. Interproximal reduction of approximal surfaces of lower frontal teeth
5. Retention (fixed retainer 33-43 + ESSIX)

Discussion:

Success of the treatment of proclined incisors with Angle class II of the whole unit consists in correct setting of anchorage forces. When there is a need for absolute anchorage, TAD’s are placed into the bone. The movement of the distal teeth forward is thereby eliminated. Nickel-Titanium closed coil springs are adapted inbetween the hooks cramped on the stainless steel archwire and TAD’s and they exert low but continuous forces. In correctly set system, the retraction of upper frontal segment is continuous without the need of activating this system. The patient left abroad after adapting and activating whole retraction unit. The evidence of self-sufficiency of this system are photographs she sent just after removal of the appliance. Tooth 32 was left mildly lingually inclined, which will be corrected with adjusted thermoformed plastic retainer.


Authors declare the case report will not be published in any national or international publications.

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