Extraction case: Treatment of a bimaxillary dentoalveolar protrusion in an adult patient with lingual appliances.

Nikolaos Skoumpourdis D.D.S., PhD, Silvia Geron D.M.D., M.Sc, Israel

www.lingualnews.com Vol. 1 No 4, November 2003

Abstract
This case report shows the treatment of an adult patient, 24 years old female with Class II malocclusion and bimaxillary protrusion with the lingual appliance.

Maximal anchorage control was achieved with the lingual appliance althogh no extraoral appliance was used, and the second premolars were extracted in order to keep maximal esthetics during treatment.The mechanics which was used in this case and enabled maximal anchorage control is described.

Diagnosis
A 24 years old healthy female came at the orthodontic clinic of the Tel Aviv University with the main complaint of protruding and overlapping maxillary central incisors.
Clinical examination revealed a symmetric face with well balanced proportions, convex profile, acute nasiolabial angle and competent lips. (Fig.1)
Intraorally she had a Class II subdivision right malocclusion with 5mm overjet and 30% of lower incisors was covered by the upper. Both arches were ovoid, symmetric and showed mild crowding. (Fig.2)
In the panoramic radiograph a full set of teeth was present with both mandibular 3rd molars mesially tiped and impacted. (Fig.3)
Cephalometric analysis showed a protrusive maxilla, small effective mandibular length and proclined maxillary and mandibular incisors. (Fig.3)

 Fig. 1: Pretreatment facial photographs

Fig. 2: Pretreatment intraoral photographs

Fig. 3: Pretreatment panoramic and cephaloimetric photographs

 Objectives of orthodontic treatment
Our treatment objectives were to:
Reduce incisor proclination resulting in a straighter profile.
Relieve the crowding in both arches.
Achieve a functional occlusion with proper overjet and overbite.

Orthodontic treatment plan
It was decided to extract four premolars in order to achieve the above mentioned objectives. Although the anchorage needs for the upper arch had to be maximum and for the lower medium we decided to extract 2nd instead of 1st premolars in the upper arch because of the following reasons:
In lingual orthodontics, the decision to extract 1st or 2nd premolars is based on the severity of anterior crowding or midline deviation and not on the amount of anterior molar movement that can be afforded. When possible, the 2nd premolar is preferable for extraction in lingual cases for two reasons:
1.this maximizes esthetics during treatment, because the extraction space is in most of the cases invisible and there is no need of an esthetic pontic to cover the gap.
2.the inset bend that is present between the canine and the posterior dentition, can interfere with space closure due to its mesiodistal dimension in a small interbracket space (1)

Additionally, anchorage loss is only 0.5mm greater with 2nd premolar extractions when assessed from cephalometric radiographs or dental casts.(2)
When considering esthetic demands, soft tissue sensitivity and patient compliance, the most desirable space closure mechanics in the adult patient treated with lingual orthodontics is sliding mechanics, with standard appliance prescription, extraction of the 2nd premolars and en-masse retraction of the anterior teeth (2).

Treatment alternatives
The main treatment approach for bimaxillary protrusion correction is 4 bicuspid extractions. Non extraction approach using extraoral appliances for retraction cannot be considered practical. Any other approach would lead to a compromised result.
A treatment alternative was to avoid extraction in the lower arch and to relief crowding by interproximal enamel reduction, resulting in a compromised result. The proclination of the mandibular incisors will not be improved.
Enamel reduction presents certain advantages: it can help avoid extractions and so no extra efforts are necessary to close in the extraction site, there is no risk of space reopening, the reduction corresponds exactly to the crowding and the length of treatment time is reduced by 30-50% which is important in decreasing the potential of root resorption. (3)

Treatment progress
Sufficient lingual crown height was present for optimum bracket positioning and there were no restorations that would preclude or complicate lingual bonding.
The lingual fixed orthodontic appliances that were used were ORMCO brackets with 0.018x0.025-inch slot from canine to canine and 0.022x0.028-inch slot for the posterior teeth. The technique used for bonding the brackets was indirect with the SILAM lingual bracket jig (4)
Treatment started by bonding the upper arch. 2nd premolars were not bonded because of the future extractions, 2nd molars because of the future placement of a Nance holding arch and right central incisor because of lack of space.
An initial archwire .017x.017 CuNiTi (Ormco) was inserted in the upper arch together with an open NiTi coil spring between right lateral incisor and left central incisor in order to create space for bonding bracket on tooth 11 (Fig. 4a).
After 6 weeks a Nance holding arch was cemented on 2nd molars to increase the anchorage on the preparation of an en masse retraction of 8 anterior teeth after the extraction of the 2nd premolars (Fig. 4b).
In the next appointment, adequate space was created for central incisor which was bonded and engaged in the archwire (Fig. 4c).
When leveling and aligning were accomplished the patient was referred to extract the maxillary 2nd premolars. After extractions, a .016x.022 SS archwire was inserted with compensation bends to counteract the transverse and vertical bowing effect which is the result of space closure. (5)

Figs. 4 a-c: ALignement stage of upper arch

The arch was divided in three segments in which the teeth were tied together with steel ligatures of figure 8 mode and en masse retraction of 8 anterior teeth began by elastomeric chain (Fig. 5a). After 3 months an impingement of the Nance holding arch in the soft tissue was noticed and it was removed (Fig. 5b). Retraction continued and total time for the extraction space closure was 7 months. Although there were compensation bends in the archwire mesio-buccal rotation of maxillary 1st molars occurred. To correct these rotations, labial clear buttons were bonded on the buccal side of the molars and derotation ties with elastomeric chains to the archwire were applied (Figure 5c). After derotation of molars a .017x.017 TMA archwire was inserted for finishing stage of treatment.

Figs. 5a-c: Upper space closure

Lower arch was bonded 6 months after beginning of the treatment. 2nd premolars were not bonded because of the future extractions and 2nd molars because the anchorage demands for the lower arch were moderate. Both canines were excluded from the bonding procedure because of their misalignment. A .0175 Respond archwire was inserted as an initial archwire.
-Figure 6a

When referred for the extractions of the second mandibular premolars, the patient refused to undergo this procedure although she was aware of the treatment plan and the impact this decision would have on it.  Therefore, it was decided compromise and relieve lower crowding by interproximal enamel reduction without correcting the inclination of incisors.

At this time lower second premolars were bonded and a 0.016 inch NiTi wire was placed to continue leveling and alignment of the arch.  One month later this was changed to a 0.016 inch stainless steel arch wire. Clear buttons were bonded to the labial surfaces of the canines and an elastomeric chain stretched between them to affect simultaneous derotation (Figure 6b →). After 2 months both canines were almost completely derotated, were then bonded and a 0.017x0.017 inch CuNiTi wire was placed to complete leveling and alignment of the whole arch.

At the next appointment the wire was changed to a 0.016 inch stainless steel arch wire and reproximation of posterior teeth took place.  This was carried out by air-rotor stripping using elastic module separator preparation as described by Sheridan (6,7).  This was immediately followed by the application of a high concentration fluoride paste to the on tooth surfaces were the enamel was reduced to enhance remineralization (Fig. 7a). Teeth were retracted into the space created, and this procedure was continued and carried forward to the anterior teeth during the ensuing appointments.  Reduction of the mesio-distal width of the incisors was done manually using metal strips. (Figs. 7b, 7c)
A 0.017x0.017 inch CuNiTi wire was placed after completing reproximation and space closure, in order to achieve the final position of the teeth. (Fig. 7d)

The brackets were debonded from both arches after a total treatment time of 18 months.

Figs. 7a-c: Interproximal reduction and alignment of lower arch

Retention
Fixed lingual retainers from maxillary lateral to lateral incisors, and from mandibular canine to canine were bonded. Clear plastic vacuum-formed removable retainers were fabricated to fit on top of the fixed retainers and were prescribed to be worn at night only.

Treatment results
Lip protrusion was reduced and significant improvement in the smile occurred. (Fig. 8)
Proper functional occlusion was created with overjet and overbite within normal limits. (Fig. 9)

Fig. 9: Posttreatment intraoral photographs

Periapical x-rays show that there is no detectable root resorption (Fig. 10)

From the panoramic radiograph we can see proper tooth positions. The patient was referred to extract the mandibular third molars because of their impactions.

Superimposition of the pre- and post-treatment cephalograms showed significant retraction of the upper incisors and slight lingual tipping of lower incisors due to the tip back position of the molar brackets (2). Upper molars were found to have moved mesially about 1/3 of the extraction space, which was compatible with the required maximal anchorage control.(Fig. 11)

Treatment objectives were achieved in a less than average treatment time and friendly esthetic appliance to the patients' satisfaction was utilized.

Fig. 10: Posttreatment cephalometric and panoramic photographs

Fig. 11: Superimposition of pretreatment and posttreatment photographs

References
1. Geron S, Shpack N, Kandos S, Davidovitch M, Vardimon A Anchorage loss, a multifactorial response. Angle Orthod 2003;
2.Geron S, Vardimon A Six anchorage keys used in lingual orthodontics sliding mechanics. World J Orthod 2003;4:
3. Fillion D. in Romano R Lingual orthodontics. 1998 BC Decker Hamilton, London pages:96-107
4.Geron S The lingual bracket jig. J Clin Orthod. 1999;32:457-462.
5. Alexander CM, Alexander RG, Gorman JC, et al Lingual orthodontics: a status report. Part 5. Lingual mechanotherapy. J Clin Orthod. 1983;17:99-115.
6. Sheridan JJ Air-rotor stripping. J Clin Orthod 1985;19:43-59.
7.Sheridan JJ Air-rotor stripping update. J Clin Orthod 1987;21:781-788.

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Adult and Lingual Orthodontics
EDITORS:
Dr. Silvia Geron D.M.D., M.Sc
Dr. Rafi Romano D.M.D., M.Sc
Dr. Pablo Echarri D.M.D., M.Sc