Lingual Orthodontics in combination with Fiber Reinforced Composites for improved eficiency and comfort.

Silvia Geron D.M.D., M.Sc., Tel Aviv University, Israel


www.lngualnews.com Vol. 2 No 1, May 2004

Abstract
The combination of Fiber Reinforced Composites (FRC) with lingual Orthodontics is advantageous for better control of tooth movement, simplification of treatment steps, oral hygiene and comfort. The technique is demonstrated in the partial orthodontic treatment of a Class I patient with x-bite of the right canine, and rotation of the left upper canine.
The patient requested to correct the x-bite only, without causing any changes in the position of other teeth, including the rotated left canine. The combination of FRC with lingual brackets provided esthetic dentition during the treatment and improved anchorage with selective desired tooth movement.  Only a few lingual brackets were used resulting in almost no tongue irritation and speech problems; oral hygiene was easy to control and no gingival inflammation was noticed.
The desired treatment goals were achieved in a very short treatment time.

Introduction
The use of Fiber Reinforced Composites presents a new era in Orthodontics. It was first introduced for the labial technique by Burstone and Kuhlberg in 2000 (1), who claimed that this technique can change the concept, mechanics and application of fixed appliances. The advantage of using this pre-polymerized fiber matrix complex that is later fully polymerized clinically, is the enhancement of mechanical properties, improved control of tooth movement and simplification of the steps performed by the clinician (2-3).
This technique is recommended for use in lingual Orthodontics as well and may provide some very important benefits.
Adult patients prefer the lingual technique in order to avoid the unattractive appearance of conventional orthodontic appliances, and because it is more successful in meeting esthetic requirements as the appliance is invisible.
However, adult patients are also much more sensitive to appliance irritation, they suffer more than young patients from tongue soreness, and their periodontal tissue is more likely to react negatively to the large lingual brackets, residual bonding material and reduced natural massage and rubbing of the palatal gingivae. Adults are also more aware of any changes in their mouths and dentition, they have higher expectations of a short treatment and a totally invisible appliance, and any unwanted movement of a tooth during any stage of treatment will not be accepted or tolerated by them.
Another problem in Lingual Orthodontics, relevant to this subject, is the well-known fact that accurate bracket positioning in Lingual Orthodontics is much more difficult to achieve, and there are more likely to be some unwanted changes in teeth position at the initial stages of treatment.
The use of Fiber Reinforced Composites in active or passive application can offer us a direction to overcome these problems.
Besides the ultimate esthetics of the dentition when FRC is bonded on the lingual side, instead of lingual brackets, it is also smooth and very comfortable to the tongue, farther from the gingivae, less irritating and less plaque-accumulating. The number of lingual brackets needed is reduced dramatically.
It can be bonded to a group of teeth and joined together to an anchorage unit, or a moving unit, providing very solid anchorage. Joining a group of teeth together with the FRC assures that these teeth will not undergo reactive movements.

Clinical Case
A 29-year-old women presented for orthodontic treatment with the main complaint of her right canine hidden inside her mouth, which, according to the patient was unesthetic and prohibited her smiling.
The patient was very satisfied with the esthetics of her other front teeth and insisted on correction of the x-bite only. Her prerequisite condition to treatment, about which she was very decisive, was not to change any other tooth position, including the rotated left canine.
 
Clinical examination revealed that she had a symmetric face, with normal facial pattern and profile, nice smile line and normal gingival exposure at rest and at smile (fig 1).

Fig 1: Pre-treatment smile and intraoral photographs
 

She had Class I dental relations with normal overjet and overbite. An anterior cross bite was present at the right canine with its antagonist. The left canine was rotated. Space analysis of the upper arch showed a lack of space of 3 mm. The lower arch was symmetric and well aligned.
Periapical and panoramic radiographs did not show any pathological signs.
The objectives of orthodontic treatment were to correct the anterior x-bite without causing any other teeth movements, especially the anterior teeth.

Orthodontic treatment plan
Since the patient objected to moving any anterior tooth, including the rotated left canine, it was decided to position the right canine in a symmetric rotated position with the left canine, and therefore the moderate lack of space in the upper arch could be ignored.
It was decided to correct the cross bite with the combination of lingual brackets and FRC that will splint the anterior teeth during the treatment and avoid any anterior movements.

Treatment progress
Combination of FRC and lingual brackets was prepared on the upper arch model for indirect bonding.
Two sections of FRC (Splint it, Jeneric Pentron Inc, 53 N Plains Industrial road, Wallingford,CT 06492) were placed and adapted to the palatal surface of the upper incisors and the upper right molars. (Fig.2). Two lingual brackets (Ormco) were bonded, on the palatal surface of the right canine and on the FRC band of the first molar.

Fig 2: Indirect preparation of combined Lingual and FRC appliance

Once the FRC bars were adapted, a low viscosity composite was added to form a protective later over the bars. A silicon impression transfer tray was prepared and the appliance was bonded indirectly. (Custom IQ, Reliance co.)
Treatment was initiated by inserting a spring into the first molar bracket, which was connected with the FRC bar to the second molar for anchorage, and to the canine bracket. The spring was activated for rotation and forward movement of the canine (Fig 3). A lower removable bite plate was delivered to the patient for nightwear, to free up the right canine and allow its movement. (Fig 4).

Fig.3: Combined Lingual andFRC appliance bonded in the mouth

Fig.4: Lower removable bite plate for night ware

At the next appointment the canine was connected with an elastic chain to the anterior anchorage unit, which included the four incisors connected with the FRC bar. The elastic chain was tied from the lingual bracket of the canine to a composite attachment on the labial surface of the right lateral incisor (Fig 5).

Fig.5: Labial composite attachment on the lateral incisor tied with elastic chain to the lingual bracket on the canine

During the treatment the upper right molar further rotated mesially since the FRC bar was broken and the reactive forces acted on the first molar only (Fig 6).

      Fig. 6: Lingual spring at the end of treatment

Debonding was done after 6 months of treatment.
The teeth were retained with a clear vacuum-formed removable retainer for a night-time use.

Treatment results
The canine cross bite was corrected, the upper right canine was rotated mesially in symmetry with the left canine and significant improvement in the smile occurred. There were no changes in the position of the anterior teeth besides the upper right canine, both during the course of treatment and at the end result. The upper right molar further rotated mesially due to anchorage loss, which is expected to relapse after debonding.
Proper functional occlusion was kept with overjet and overbite within normal limits. (Figure 7)

Treatment objectives were achieved in a very short treatment time with an esthetic and comfortable appliance to the patients' satisfaction.

Fig.7: Post treatment smile and intraoral photographs

References
1. Burstone C.J., Kuhlberg A.J., Fiber-Reinforced Composites in Orthodontics, J. Clinc, Orthod  34;5:271-279, 2000

2. Freilich M.A., Karmaker A.C., Burston C.J., Goldberg A.J., : Development and clinical application of a light-polymerized fiber-reinforced composite, J. Prosth. Dent;80;311-318,1998

3. Goldberg A.J., Burston C.J., :The use of continuous fiber reinforcement in dentistry, Dent. Mater.:8;197-202,1992.

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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