CLASS II NON-EXTRACTION TREATMENT WITH SELF LIGATING LINGUAL BRACKETS

Silvia Geron, DDS. MSc.


www.lingualnews.com  Vol 2 No 2 November 2004

Introduction
The lingual technique is more difficult than the labial technique because of several reasons, the difficulties in accurate bracket positioning, the discomfort to the  patients and the mechanical difficulties. The small arch and small inter-bracket distance in the lingual technique reduce the appliance efficiency. Torque and the rotations are more difficult to control. Wire bending in a short interbracket distance is more difficult and less effective.  A common problem with horizontal slot lingual brackets is the difficulty in obtaining complete archwire engagement and the tendency for the archwire to be pulled out of the bracket slot. A ligation method termed the double-over tie is used with both metal and elastic  ligatures to improve the ability to eliminate rotations and maintain archwire engagement throughout treatment ¹. This type of ligation increases frictional resistance; and is time consuming. Changing the elastic ligature is required frequently throughout treatment for oral hygiene purpose and because of force decay of the elastics.

If a steel overtie ligation is used instead of elastic modulus, friction is reduced and wire engagement is improved, but it significantly increases chairside time, and it may occasionally be displaced between appointments and cause discomfort.to the patient and soft tissue trauma, leading to more emergency appointments.

The self ligating brackets have some important benefits that can contribute to the efficiency of Lingual Orthodontic treatment. The performance of the lingual orthodontic appliance may be improved because of some qualities of the self ligating brackets. Very low friction with self-ligating brackets has been clearly demonstrated and quantified in works by various authors ^2-5. With low friction the net tooth-moving forces are more predictably low and the reciprocal forces correspondingly smaller, leading to better anchorage control. Secure, full archwire engagement maximizes the potential long range of action of low elasticity modulus wires and enables precise control on rotation, tip and torque. Activation range is increased and fewer appointments are needed for activation ⁶.

One of the main benefits of the self ligating brackets is improved clinical efficiency and time saving. Arch wire replacement is quicker and easier. Several works demonstrated a significant reduction in ligation time with labial self ligating brackets compared to wire ligation of conventional brackets ^7-8. Clinical time is reduced also because there is no need to change the ligatures every appointment for hygienic purpose.. It should also be remembered that archwire 'ligation' using self-ligating brackets does not require a chairside assistant to speed the process, since self-ligating brackets require no passing of elastomeric or wire ligatures to the operator during ligation. The clinically significant improvements in treatment efficiency is supported by several works with labial brackets ^9-10 demonstrating reduction in treatment time of 4-7 months. The following case report shows the treatment course of an adult Class II patient treated non- extraction with Lingual self ligating brackets.

Fig 1: Pre-treatment facial photographs

Case report
A 24 years old healthy female presented for treatment with the main complaint of crowding of the lower teeth and mal-alignment of her upper incisors. She was generally satisfied of her smile and facial appearance, and emphasised that she does not want to changed it. Clinical examination revealed a symmetric face with well balanced proportions, convex profile with slight bimaxillary protrusion (Fig.1).The dentition was well balanced within the face, corresponding to the standard norms of incisal exposure at rest and smile, gingival exposure and smile width.

Fig 2: Pre-treatment intra oral photographs

She had an Angle's Class division 1 malocclusion (Half unit) with a 5mm overjet and 30% overbite. Both arches were ovoid, symmetric with moderate crowding in the lower arch and mild in the upper arch. Upper canines were severely abraded and upper central incisors were extruded by 1 mm. Gingival margins of the upper incisors were below the correct position, and were at the same height of the lateral incisors. (Fig.2).

Fig 3: Pre-treatment panoramic x-ray

On the panoramic radiograph all permanent teeth could be seen, except upper left and lower right third molars. Lower left and upper right third molars were mesioangular impacted (Fig.3).

Fig 4: Pre-treatment cephalometric x-ray

Cephalometric analysis shows orthognathic skeletal relations, and proclined maxillary and mandibular incisors (Fig.4).

Fig 5: Evolution LT bracket mounted on the Lingual Bracket Jig

Treatment objectives
The treatment objectives were to eliminate crowding and rotations, reduce incisor proclination, level and align the dental arches.

Treatment plan
It was decided to treat this patient in non extraction approach since she emphasised that she did not want the orthodontic treatment to effect her face and smile in any way. It was decided to use interproximal reduction and Class II elastics to achieve treatment objectives.

Treatment progress
Lingual self ligation were used ( Evolution LT,Adenta production and sale of orthodontic products. Germany)with 0.018x0.025-inch slot . Bracket positioning was prepared for indirect bonding with the SILAM Lingual Bracket Jig ¹¹ (Fig 5), (although the manufacturer recommendation is to use special "smart Jigs" and the "Hiro" system). Upper and lower brackets from first molar to first molar in the lower arch and second to second molar in the upper arch were bonded at the same appointment, except for the lower left central incisor and canine, since the crowding did not allow proper bracket positioning on these teeth. A Nitanol .014" archwire (Adenta) was inserted as initial wire for levelling and alignment. (fig 6). The patient had slight speech disturbance which was almost not noticeable and disappeared by the next appointment.

Fig 6: Upper and lower self ligating brackets brackets bonded

After 4 weeks she came without the brackets on the second molars, which were not rebonded.The alignment improved and a .016" stainless steel (SS) upper archwire was inserted with step up bend for the correction of upper incisors position. The lower left canine bracket was bonded and engaged to the Nitanot archwire. Four weeks later, interproximal reduction was done in the upper and lower arch. A chain elastic was used in the upper arch from second premolar to second premolar, while the molar and second premolar brackets were tied with ligature wires. This type of chain engagement is used to avoid mesio-bucal molar rotation. A month later the lower central incisor bracket was bonded, and by the next appointment, 4 months into treatment, alignment was completed and the lower archwire was changed to .016 SS archwire. The patient was instructed to wear Class II elastics, applied on a kobayashi ligature on the upper canine brackets and a and post lateral cephalogram.

The next appointments were set with two months interval, for check up of the Class II correction. The brackets were debonded from both arches after a total treatment time of 10 months. All appointments except for the bonding and debonding were scheduled for 15 minutes and lasted even less.

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
Crowding was eliminate, alignment and levelling of both arches were achieved. Proper functional occlusion was created with overjet and overbite within normal limits. (Fig 7)
 

Post-treatment x-rays show that there is no detectable root resorption (Fig 8) The patient was referred to extract the mandibular left and maxillary right 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 (Fig 9)

Conclusions
Treatment objectives were achieved in a very short treatment time, no bracket failure, no emergency appointments and with short  appointments. The patient was very satisfied from the aesthetic appliance, the short treatment time and the final result accomplishing her
expectations (fig 10).
This Case report demonstrates the significant potential of self-ligating brackets in improving Lingual Orthodontics treatment efficiency, patient comfort and in reducing chairside and treatment time.

References
1. Alexander M., Alexander R.G., Gorman J.C., Hilgers J.J., Kurz C., Scholz R.P., Smith J.R Lingual Orthodontics: A Status Report: Part 5- Lingual Mechanotherapy.JCO 1983 Feb (99 - 115)
2. Shivapuja PK, Berger J. A comparative study of conventional ligation and self-ligation bracket systems. Am J Orthod Dentofac Orthop 1994; 106: 472-480.
3. Berger JL. The influence of the SPEED bracket's selfligating design on force levels in tooth movement: a comparative in vitro study. Am J Orthod Dentofac Orthop 1990; 97: 219-228.
4. Pizzoni L., Ravnholt G., Melsen B., Frictional forces related to self-ligating brackets E J Orthod 1998 20(3)283-291
5. Hain B., Dhopatkar A., Rock P., The effect of ligation method on friction in sliding mechanics Am J Orthod Dentofac Orthop 2003 ;123:416-422
6. N. W. T. Harradine.Self-ligating brackets: where are we now? Journal of Orthodontics, Vol. 30, No. 3, 262-273, September 2003
7. Maijer R, Smith DC. Time saving with self-ligating brackets. J Clin Orthod 1990; 24: 29-31
8. Shivapuja PK, Berger J. A comparative study of conventional ligation and self-ligation bracket systems. Am J Orthod Dentofac Orthop 1994; 106: 472-480
9. Harradine NWT. Self-ligating brackets and treatment efficiency. Clin Orthod Res 2001; 4: 220-227
10. Eberting JJ, Straja SR, Tuncay OC. Treatment time, outcome and patient satisfaction comparisons of Damon and conventional brackets. Clin Orthod Res 2001;
11.Geron S The lingual bracket jig. J Clin Orthod. 1999;32:457-462.

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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