March, 2000

Indirect Bonding — A Management “Pearl”

En Español

Dr. Richard Myers

Indirect bonding has been an integral part of our practice for a number of years now. In fact, ninety percent of the full appliance set-ups done in our office are bonded indirectly using the technique that is described in this article. It is a technique that takes time and perseverance to master. Many offices have attempted it, only to suffer from failures and mishaps that have discouraged them from continuing with the use of this technique. Indirect bonding is a very technique-sensitive procedure that requires discipline, organization, a team approach, and the ability to accept from the beginning that it will not work perfectly every time. Given these parameters, indirect bonding can offer the user the following advantages over direct bonding of attachments:

1. A placement technique for attachments unparalleled for accuracy. Most of us can place a bracket on an anterior tooth with good accuracy; an upper second bicuspid or lower six-year molar offers more of a challenge. It is easy to accurately position any bracket and achieve excellent base adaptation on any tooth if it can be done on a model that can be hand-held and observed in any plane of space so that the axial inclination and morphological variations of the crown can be studied.

2. Any technique that can reduce patient chair-time without sacrificing quality merits consideration; any technique that reduces chair-time while enhancing quality is a must. Indirect bonding offers these very characteristics, significantly reducing the time required to complete a full strap up when compared with even an efficient direct bonding team.

3. Reduce doctor-time in appliance placement equates to economics and quality of care. The actual doctor-time required in completing a full strap-up is embarrassingly small when equated with the more familiar techniques. And this without abrogating the responsibilities we all have to our patients.

4. We all like to think that we are making maximum use of auxiliary personnel, but indirect bonding carries that to a higher level. Each step in the process, from impression taking to cleanup following bonding, can utilize auxiliary personnel. Yet the doctor retains the ability to interject himself into the process at any stage and in any manner that he may feel proper. Most importantly, the all-important final check of attachment positions, and any adjustments deemed necessary remain with the doctor.

5. And finally, a fringe benefit of using the indirect bonding technique that we realized early on was the great opportunity it presents in staff training. Conveying the concept of attachment positioning to auxiliaries is not always easy, but when done in conjunction with bonding set-ups on the lab bench, a much better teaching environment and more logical approach is available. And for those utilizing auxiliaries in bonding in the mouth, excellence in bracket positioning can be realized much more quickly after placement of many hundreds of brackets on models first.

Indirect Bonding Technique

The actual technique of indirect bonding can be thought of in two phases; tray preparation and bonding. While these two procedures represent individual components that we all use on a daily basis, they will be broken out here for the purpose of clarification of our office technique. Tray preparation can be broken down into the following steps:

• Impression taking
• Work model preparation, bracket placement
• Transfer tray fabrication, and
• Tray finalization

1. Impression taking involves utilization of a rigid tray, as would be used for an impression upon which an appliance is to be constructed. A high quality impression is essential, and must be taken no more than 14 days prior to the anticipated bonding date. At the time of the impression a lab work card is made indicating the patient name, teeth to be bonded, due date of the case, and anything unusual about the case (i.e. irregular incisal edges, fractures, ceramic brackets instead of metal, etc.).

   

2. Work model preparation involves immediate pouring of the impression in stone, avoiding any chance for distortion, and assuring that no air bubbles or inclusions result. A small base is desirable to permit ease of working with the model, and there should be adequate soft-tissue recorded gingivally to the teeth to allow transfer tray material to flow later. The model is dried prior to any attempt to work further with it.

   

3. The first step in bracket placement is to have the full armamentarium laid out and available. Lines are scribed on the work model indicated the axial inclinations of those teeth to be included, and bisecting the crown; this assists in bracket orientation which follows. Preselected brackets are then "fitted to the teeth" with any necessary contouring and adapting of the bases prior to placement on the teeth with 3M Unitek Lab Adhesive. This material allows five to ten minutes in which the bracket positions can be changed and adjusted as desired. Ideally, the doctor who is responsible for checking the case for accuracy and acceptability should do so during this time; if impossible, any brackets can be reset if repositioning is necessary using new adhesive at any later time. A minimum of 15 minutes should be allowed before any further procedures are done to permit thorough set of the adhesive. A doctor always "signs off" on the case at this point, indicating acceptable accuracy of attachment placement. Attachments other than brackets, i.e. hooks, etc., can be managed in the same manner.

   

4. Transfer tray fabrication involves the use of the Examix dispenser and the Examix vinyl polysiloxane impression material. In our office, we use two clinicians to fabricate the transfer tray. The first clinician injects the material over the model working from one posterior tooth around the arch to the other side. The material is allowed to flow incisally rather than gingivally in order to give the tray a good index. The second clinician then takes the model and dips her fingers into a bowl of water to avoid sticking to the tray material and gently taps the tray into the brackets and in the inter-proximal areas of the teeth. This is the most critical part of the tray fabrication because it allows the material to engage the brackets and adapt well to the surfaces to the teeth. We recommend applying this technique to several practice models prior to attempting it clinically.

   

5. Tray finalization. After about five to ten minutes the material will begin setting and you can put a midline indicator and the initials of the patient on the model with a pencil. You soak the model in warm water for as long as it takes to dissolve the lab adhesive. Once the tray is removed from the model it is placed in an ultrasonic for ten minutes to assure that the bracket pads are clean. The tray is then flushed very well with cold water to assure that all soap is off the mesh of the brackets. The tray is then air dried and trimmed with scissors making sure it clears the sulcular area so that fluid will not rise up and contaminate the teeth when placing the brackets. We then bag the tray and apply an appropriate patient tag.

   

Bonding Procedure

The bonding procedure likewise is comprised of five rather distinct steps: prophylaxis and isolation, etching, sealant placement, tray seating, and tray removal and clean-up.

1. Prophylaxis and isolation are nothing new or different. A thorough prophy, utilizing a rotary cup or brush and a non-oil based paste, or better still pumice alone, is essential. Any teeth that have facial restorations or are considerably hypocalcific should be "roughed up" slightly using a green stone in a slow-speed hand piece to enhance the bond ability of the surface. Cheek blotters (Dri Angles) are placed first, followed by cheek retractors, cotton rolls, and an aspirator tip.

   

2. Etching follows the usual procedure. After drying with air, the liquid etch is blotted onto the surfaces with a cotton or foam ball. The etchant usually remains for 20-30 seconds. If ceramic brackets with mechanical-lock bases are to be used, the time is usually no more than 20 seconds; if hypocalcific teeth, the time may be 60-90 seconds. Etchant is thoroughly washed off at the appropriate time with excessive water flushing.

   

3. Next the whole arch is air-dried, and subsequently a few teeth at a time are air-dried and sealant placed on that segment only using a disposable brush; next the anterior segment is thoroughly air dried and sealed; and finally the other buccal segment is thoroughly air-dried and sealed. We have found that one most important factor in avoiding bonding failures, especially in the posterior regions, is to place sealant while the enamel surfaces are thoroughly desiccated; and before even the breath is able to impart any moisture to the surface; once sealant has been placed the surface is no longer as susceptible to moisture contamination, though one should avoid salivary contamination or any significant moisture contamination from any source. We are successful in bonding second bicuspids and lower first molars as long as these guidelines are followed.

4. While the final sealant is being applied, the assistant mixes the adhesive, loads it into a disposable C-R syringe, and applies the correct amount carefully to the pad of each bracket in the tray. The clinician then seats the tray assuring that the occlusal/incisal indices are positively seated, that the bracket surfaces are against the teeth as intended, and then maintains the tray in position, motionless, until the adhesive is cured. Subsequent to loading the brackets, the assistant squirted the rest of the adhesive in a ball on a gauze square and continues to observe it, advising the clinician when the material is hard; since the warmth of the mouth results in a faster set of the material than will take place on the gauze, by the time the latter material is cured you can be certain that that in the mouth is as well. If two arches are to be bonded at the same time proceed with the second arch, repeating the above procedures, prior to removal of the first tray.

   

5. Immediately following set of the indicator material, tray removal and clean up can be commenced. No special care is necessary in removal of the tray(s); a scaler can be used to tease the material away from the teeth, starting on one side and progressing to the other. Once the trays are removed the patient should have the retractors, cheek-blotters, any cotton rolls, and aspirator removed and allowed to rinse. They have been holding their mouth open for quite a period of time and "deserve a break". A scaler should be used to check the gingival margins and interproximals for flash, as well as to check for bonding material under the bracket wings and voids anywhere. Floss the interproximals to assure that no "bridging" has occurred. Finally, check the bracket positions to assure that nothing occurred during tray fabrication that could have resulted in one or more brackets shifting from their prescribed positions on the model. This does occasionally occur. Archwire placement can be accomplished after the adhesive has set for a minimum of 5 minutes, and from this point on there are no differences from any other technique.

   

A few more rules of thumb for indirect bonding:

1. If four or fewer brackets are to be placed in an arch, we direct bond these; more than four brackets will be indirectly bonded, even if there are already other brackets in place in that arch.

2. If a patient cancels the set-up visit subsequent to impression-taking for indirect bonding, and it cannot be rescheduled within the 7- 1 0 day limitation mentioned earlier, the work model is discarded and the patient rescheduled for a new impression. It isn’t worth taking a chance on even the slightest change in tooth position ruining the set-up.

3. Even teeth that are significantly displaced from the arch, i.e. high cuspids, crossbites, can usually be included in the tray; teeth that are insufficiently erupted are usually not included.

4. Unusual bonding challenges, i.e., ceramic restorations, large metal restorations, hypocalcific teeth, are still bonded indirectly utilizing the specific techniques recommended by the adhesive suppliers.

Good luck with your efforts! Remember to anticipate problems at the beginning; don’t be discouraged by early failures, they will disappear. Attempt to trouble-shoot when a failure occurs – what caused the problem? More often than not, a break in proper technique resulted in the failure, and cleaning up your technique will solve the problem once and for all time. And keep your eye on the donut, not the hole; the technique will pay great dividends if you only persevere.

• Presented before the NESO Annual Meeting, Providence, Rhode Island, November 9, 1998
• Presented before the AAO Management Conference, Philadelphia, Pennsylvania, February 6, 1993
• Presented before the AAO Management Conference, Atlanta, Georgia, February 28, 1992

Product Information

• Lab Adhesive – 3M Unitek
• Tray Material – Examix cartridges – (polysiloxane impression material, heavy body)
• Tray Material Placement – MixPac Injector syringe with monophase mixing tips – Examix
• Baggies – Glad, etc.
• Cheek Retractors – Caulk
• Cheek Blotters – Dri Angles
• Bonding Products – Regular-set Excel paste/paste and sealant best for indirect technique Reliance
• Bonding enhancement products – Enhance for fluorosed enamel and composite and metal restorations; Porcetch and Porcelain Conditioner for ceramic facings – Reliance
• C-R Syringe – Centrix
• Tubes and Plugs – Centrix

Contributed by:

Dr. Richard Myers
Associate Clinical Professor at the Eastman Dental Center of the University of Rochester School of Medicine and Dentistry and in Private Practice, Oneida, New York

Tags: bonding