Different rebonding procedures in Lingual Orthodontics

Silvia Geron, Nir Shpack, Israel

www.lingualnews.com, Vol 1 No 2, March 2003

Precise placement of brackets is an essential part of every orthodontic treatment, and especially lingual orthodontic treatment. Accurate bracket positioning reduces the chair side time, shortens the treatment time and improves the final results (1).
Several techniques for accurate lingual bracket positioning are described in the orthodontic literature (2-6). But even with a perfectly accurate bracket positioning technique, and a perfect laboratory and technician, the lingual bracket positioning technique is confronted with some difficulties:
1. Overlap of teeth at the beginning of treatment and a small inter-bracket span, which does not allow the correct bracket positioning at the initial stage of treatment.
2. Difficulties in keeping a dry field during the bonding procedure (tongue, saliva)
3. Bonding failure during the treatment.

These are severe complications in the course of the lingual orthodontic treatment, which extend treatment time and may lead to compromised results. For this reason the aim of every lingual treatment should be to achieve the most accurate and best adhesion possible between bracket and tooth, in order to avoid premature debonding.
Therefore a reliable, accurate and simple rebonding procedure is a very important requirement for the successful integration of lingual orthodontics into practice.

Different rebonding procedures are required, depending on:
1. The initial bonding procedure, accuracy and availability of the bonding transfer tray and the debonded bracket.
2. The stage of treatment and the clinical condition of the rebounded tooth
3. The bonded surface: enamel, porcelain or metal.

For successful rebonding, in any technique, the use of intraoral microetching (sandblasting) prior to bonding is necessary (7). The microeching should be applied to the bonded surface (enamel, ceramic or metal) as well as to the resin base of the debonded bracket, for 5-6 seconds.
On enamel surfaces this procedure should be followed by etching and bonding as usual, (2,7) on ceramic surfaces a special ceramic etching and ceramic primer (Ultradent) should be used, while on metal surfaces a metal primer (Reliance) should be used prior to bonding, according to manufacturer instructions. During rebonding, it is important to use the same bonding material that was used initially used bonding. 

The different bonding procedures are summarized in the following chart (Fig 1).

Fig 1: Different rebonding procedures

In case the debonded bracket is in unequivocal seat on the tooth, the easiest way is to bond the bracket directly, according to the guidance of the composite pad of the bracket.
If the bracket is not in an unequivocal seat, we have to check if the initial transfer tray is available for rebonding and is in good condition. If the initial transfer tray was made from a silicone impression material, a section of the original transfer tray may be used for the rebonding process, by repositioning the bracket into its place in the transfer tray, sectioning this part of the tray and bonding it indirectly (Fig 2)

Fig 2: A section of the original transfer tray may be used for the rebonding process, by repositioning the bracket into its place in the transfer tray, sectioning this part of the tray and bonding it indirectly

This rebonding technique is very technique sensitive. It is difficult to control the position of the single tray, due to the reduced index surface (7), and it is also difficult to control the pressure applied by the clinician on the tray. Due to its increased flexibility, the tray may position the bracket more gingivally or with the incorrect angulation.
The Hiro technique (5) offers a good solution for the problem of rebonding. When a bracket is lost during the treatment, a new bracket can be tied to the acrylic core and rebonded at the same level of accuracy as the initial bonding. This is a very major advantage of this system.

If the transfer tray is not available for rebonding, when the tooth is in the correct position, and a rectangular archwire is engaged, then the wire can be used as a reference guide for the bracket rebonding. (Fig 3)

Fig 3: The wire can be used as a reference guide for the bracket rebonding, if the tooth is in correct position and a rectangular wire is engaged.

When the tooth has moved from its place after it was debonded, sometimes it is possible to use elastics to pull the tooth to its correct position, and then use the archwire for guidance. In some cases, the debonded bracket can be left ligated to the wire, and after sandblasting and etching the composite/tooth surface, the bracket can be rebounded without being untied
(Fig 4)

Fig 4: It is possible to use elastics to pull the tooth (b) to its correct position before rebonding.

If the transfer tray is not available for rebonding, or the bracket has to be repositioned, a new transfer tray has to be prepared in the laboratory, using the initial model, or taking a new impression of the debonded tooth. Alternatively a direct bracket positioning procedure can be used with the Lingual bracket Jig (LBJ). (4)
The LBJ offers the possibility to directly bond a bracket, having the same degree of control on bracket position as in the laboratory, with no need for another laboratory procedure.
Direct bonding with the LBJ requires the prescriptions of the initial bonding regarding in-out distance and height of bracket positioning. These prescriptions can be derived from one of the neighboring teeth, and transferred to the rebonded tooth. (Fig 5)

Fig 5:Direct bonding with the LBJ requires the prescriptions of the initial bonding regarding in-out distance and height of bracket positioning. These prescriptions can be derived from one of the neighboring teeth, (a,b) and transferred to the rebonded tooth (c,d)

Conclusions
For a reliable, accurate and simple method of rebonding, one has to follow carefully the simple rules of bonding: use microetching before bonding, use the correct etching materials and conditioners for the different bonded surfaces, use the same bonding material that was used for the initial bonding, and choose the simplest way for rebonding, according to the clinical condition as described in the above chart. (Fig 1)

     
Readers of the electronic Lingual Orthodontics Journal LINGUALNEWS are invited to submit their ideas for solving the rebonding problem in LO. Please email: info@lingualcourse.com

The next "Clinical problems and Solutions" will focus on "Finishing bends", "Improving Patient Comfort",
Readers are invited to contribute their ideas on these subjects, as well as a new subject to be discussed in the following issues.
 

References

1. Creekmore TD. Lingual orthodontics - Its renaissance. Am J Orthod Dentofac Orthop 96: (120-137) 1989
2. Fillion, D. The Resurgence of Lingual Orthodontics. Clinical Impressions, 7(1)2-9, 1998
3. Huge S.A. The Customizes Lingual Appliance Set-Up Service (CLASS) System in Romano, R. Lingual Orthodontics, B.C. Decker, Hamilton, London 1998 163-173
4. Geron S. The lingual bracket jig. J Clin Orthod 1999;33:457-63.
5. Kim Taeweon, BaeGi-Sun, Cho Jaehyung. New Indirect Bonding Method for Lingual Orthodontics. J Clin Orthod 2000;34;6:348-350.
6. Weichmann D. Modulus-Driven Lingual Orthodontics. Clinical Impressions, 10(1)2-7, 2001
7. Weichmann D. Lingual Orthodontics (Part 3): Intraoral Sandblasting and Indirect Bonding. J. Orofac Orthop 2000;61;280-91

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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