Indirect Bonding: The Tech Effect by Jack C. Fisher, DMD

Issues
Traditional manual methods of indirect bonding can be time-consuming, tedious and technique-sensitive.

• Meticulous measuring, scribing and placement of brackets on dental models can lead to even slight mistakes that cost extra time, money and materials later in the patient’s treatment.
• For manual methods to provide reliable, predictable results that the patient and doctor can visualize before treatment starts, the teeth of the dental model would need to be reset in wax with full archwire expression in brackets connected to the teeth.
• Design and production of the transfer tray are intertwined—designing the spaces and edges of the two-part transfer tray happens during production.
• The brackets are covered with multiple materials during production of the tray and could be moved inadvertently. The doctor cannot verify the final positioning of each bracket until the tray is complete.
• When placing the finished tray of brackets on the patient’s teeth, finger pressure must be applied to position the tray where the brackets will not be too near, or far from, the gingival tissue. The inherent flexibility of the inner tray can lead to asymmetrical overseating of brackets when pressure is applied unevenly at different places along the tray.

Drawbacks of traditional methods—including, but not limited to, time needed, detailed hand work, multiple opportunities for error and difficulty previewing the outcome—also have contributed to avoidance of indirect bonding.

Solutions
Such drawbacks are no longer applicable in this new era of indirect bonding. Although many of the principles are basically the same, the original methods have been replaced by digital techniques that streamline the process.

Software reduces the inconsistency that each manual step of the former process introduces. Highly time-intensive procedures are now automated, yielding greater precision of initial bracket placement. Orthodontists and staff can go from start to finish doing all steps completely in their offices.

A system of indirect bonding that encompasses the following features can be the key to opening many more orthodontists to implementing it in their practices.

• Intraoral scans are prone to having holes. Importing the scans into software that repairs them can supply high-quality digital models for virtual treatment planning.
• Software specifically for indirect bonding enables doctors to determine bracket positions virtually, with no need for dental models or hand tools.
• The ease of creating multiple treatment plans digitally provides options to show patients for making decisions during consultations. Patients can preview and compare the anticipated results and quickly agree to start treatment.

• With digital indirect bonding, both the designing and production of transfer trays are automated. Isolating the designing from production allows the opportunity to verify bracket positions before making the tray. Adjustments of the design can be made without wasting materials, and can be completed in less time than remaking a poorly fitting tray.
• Instead of a lab technician shaping the tray on a dental model while making the layers of the tray, covering the brackets and trimming excess material, digital methods enable custom shaping of the coverage of each bracket so it doesn’t have too much or too little material holding it in the tray. The doctor can digitally specify the contours of the tray to prevent brackets from being trapped in it.
• Since trays are designed in the software, no physical models are required for placing brackets. Bracket positions on the virtual setup are precisely matched on the virtual tray. This gives the doctor final say about the bracket positions, before the tray is made.

• With increased availability and affordability of 3-D printers, orthodontists can do 3-D printing in their own offices with no lab fees or lengthy delays for shipping. Outsourcing to a lab for production is unnecessary.
• The 3-D printer must be capable of printing the fine details of the brackets; otherwise, the brackets won’t fit correctly in the tray—even if it was designed perfectly.
• Three-dimensional printing the transfer tray eliminates the former need for a dental model when making the tray. Only a single material is needed for the tray, and no thermoforming is involved.
• Using a printing material that makes the tray rigid gives the tray a positive “stop” when placed on the teeth.
• Before starting bonding, it’s important to practice putting the rigid tray on and off the patient’s teeth, to find and relieve undercuts so that the tray has a passive fit. It shouldn’t snap into place—the tray should be passively seated in the correct position without any secondary movement because of being too loose.
• While designing the tray, or after printing it, the tray can be split into segments that make insertion and removal simpler.
• When the tray is designed and produced to fit passively, no finger pressure is needed to hold each segment on the teeth.
• After attaching and curing the brackets on the teeth, the tray can be gently lifted off, presuming the tray design doesn’t trap brackets in their spaces and the undercuts have been properly relieved.

Outcomes
An indirect bonding system with the previously mentioned features for planning, design and production can yield multiple favorable results.

Accuracy: With digital treatment planning, digital tray designing and onsite 3-D printing, direct-to-ideal tooth positions and bracket positions are possible. That precision greatly reduces rebond appointments and round-tripping of teeth. True straight-wire treatment can be used and minimal (if any) robotic wire-bending is needed, because the brackets are where the doctor wants them.

Timing: Working entirely in the doctor’s own office contributes to shorter overall treatment time. No need for technique-sensitive manual production of transfer trays. No need for back-and-forth with labs to verify that technicians have correctly placed brackets, and no worrying that appliances will arrive in time for the bonding appointment. Transfer trays can be designed, printed and used promptly.

Expenses: Costs such as these can be greatly reduced, and even eliminated, by using digital indirect bonding and in-house 3-D printing:

• Lab services and materials for transfer tray designing and production
• Wire-bending services
• Shipping
• Dental models for setups
• Rebond appointments
• Remaking of trays that may not fit because of changes with the patient’s dentition (such as eruptions) during the delay for arrival of the trays.

Versatility: The right combination of software and 3-D printer enables a doctor to provide a patient with aligner treatment for one arch that needs only minor movement of the teeth, while also providing bracket treatment for the other arch.

• Software, such as Ortho Insight 3D from Motion View Software, gives the doctor control (personally and by designated staff) because it’s entirely self-contained in the office, sparing the ongoing drain of paying for lab fees. The software should allow treatment of the virtual patient, including virtual models, X-rays, photos and facial scans such as the ones seen above. It should also give the doctor final approval for the design of the transfer tray, including coverage of brackets, thickness of tray, and virtual splitting of the tray so it can be 3-D printed in sections if preferred. The software should include options to optimize brackets for full expression of torque to create custom bases.
• A 3-D printer that’s specifically made to print trays with finely detailed spaces for brackets, such as the iPrint 3D model 700 made by iPrint 3D, will enable the most accurate transfer to the teeth. User experience shows that just because a 3-D printer can print models for aligners, the same printer isn’t necessarily accurate enough to print transfer trays. If a 3-D printer even slightly changes torque, angulation or vertical height of the space where a bracket belongs, then bracket placement precision is reduced and no longer able to attain the same goals. That would defeat the main advantage of doing indirect bonding, which is the precision of initial bracket placement for the goal of higher-quality results in shorter time.

To move forward in the new era of indirect bonding, orthodontists can take full advantage of specialized software and 3-D printer options to build an indirect bonding system, giving them full control in their own offices, on their own schedules. The benefits of such a system have a positive effect on time, money, treatment results, and overall patient enthusiasm and satisfaction.

During three decades of experience, including private practice at Artistic Smiles Orthodontics in Memphis, Tennessee, Jack C. Fisher, DMD, has taught residents at NYU and the University of Louisville, and currently teaches at Vanderbilt University and the University of Tennessee. An inventor, he holds several U.S. patents, with strong interest in skeletal anchorage devices. Fisher is also a pilot and loves skiing. Whether lecturing, teaching or practicing, he’s passionate about his profession and treats every patient as family. His practice even has a patient-care dog, Smiley, who is trained to help alleviate patient anxiety.