Fit to Print (Part 1) by Dr. Rooz Khosravi

Categories: Orthodontics;
Fit to Print (Part 1) 

The ‘right’ 3D printer and processes for an in-office aligner system will vary according to each practice’s particular goals and needs

Part 1 of 2

by Dr. Rooz Khosravi

Advances in desktop 3D printing, the introduction of digital software packages designed to help move teeth and the availability of various thermoforming plastic films have all contributed to an era in which orthodontic practices are able to adopt in-house protocols to create their own clear aligners. This trend mirrors what’s happening in the dental industry, where practices that have opted into digital dentistry are manufacturing appliances such as surgical guides and crown and bridge models in-office.

What is an in-office aligner system?

Aligner therapy has significantly changed since its inception in the 1970s. Utilizing CAD/CAM technology to fabricate aligners was the first major shift in aligner therapy, when Align Technology automated the tedious process of creating aligners that conventionally had been done in-office or at a local dental lab. Fast-forward to 2021, and we have a plethora of clear aligner systems, differentiated through parts of the system process. For example, the SureSmile Advanced platform allows the combination of fixed appliances with aligners, and the Clear X Aligner system claims reactivation of aligners.

Along with the expansion of commercially manufactured aligners, orthodontists and dentists began to make clear aligners in-house. Advances in desktop 3D printers and the introduction of various digital platforms to move teeth significantly accelerated the adaption of this protocol.
The four components of an in-office aligner (IOA) system are:

  • The aligner manufacturing process.
  • The thermoplastic film of choice.
  • The brand identity of these aligners.
  • The indication of in-house fabricated aligners for orthodontic care.
This article seeks to provide an overview on these aspects.

Why do I need to set up an in-office aligner system in my practice?

Before getting deep into the components of an IOA system, let’s go over the benefits of implementing this protocol in your practice.

Digital technology has become an integral part of our daily practice. From a macro-level view, most practices use digital practice management software to address daily administrative tasks, including tracking patient care, managing financial aspects of the treatment, and communicating with patients over emails or texts. From the patient care perspective, digital technology ranges from a simple use of digital photography for diagnostic purposes to 3D-printing appliances to render the therapeutic care. Cone-beam computed tomography (CBCT) units and 3D intraoral scanners are becoming common equipment in dental practices, so a growing group of practices has begun 3D-printing dental models or appliances.

In sum, digital dentistry is here to stay. From the financial and patient care perspectives, it makes sense to adapt our daily practice style to maximize the use of digital technology in hand.

How does a provider benefit from an IOA system? This journey often starts with buying a 3D printer to fabricate clear retainers in-house. Cost reduction and quick turnaround are the primary reasons for making clear retainers from 3D-printed dental models in-house. The next logical step forward is to establish protocols to help with active clear retainers—specifically, fabricating one or a few clear retainers (i.e., aligners) designed to move a limited number of teeth to improve minor misalignments. Some providers push this further to fabricate aligners for limited or comprehensive orthodontic care.

Access to on-demand aligner options opens possibilities in daily practice of orthodontics. However, this does come at the expense of challenges to set up and maintain an in-office aligner system.

It is essential to identify the main reason you want to set up an IOA system (Fig. 1). Are you planning to use in-house fabricated aligners for patients who need correction of minor relapse, limited nine-month orthodontic care or comprehensive care? Are you going to treat some malocclusions with a hybrid appliance, mixing fixed appliances with aligners? Do you want to have a fulltime digital technician? Answers to all these questions help you to morph the extent of your in-office aligner system.

Fit to Print (Part 1)
Fig. 1: A schematic representation of technology adoption. From left to right, these providers opt not to establish an in-house appliance fabrication to full integration of in-house appliance fabrication, respectively.

How can I implement an in-office aligner system in my daily practice?

Components of an in-office aligner system are similar to a third-party manufacturing system, despite relevant adjustments in each step matching the process to a smaller yet customizable scale. One ought to harness the customizability of in-office aligners; for example, the gingival trim line can be adjusted based on the treatment plan. Additionally, a hybrid appliance (fixed appliances and aligners) can be fabricated with localized selective blackouts to optimize the retention of the aligner.

The aligner manufacturing cycle (Fig. 2) divides into digital and analog segments. Each part entails various components.

Fit to Print (Part 1)
Fig. 2: Aligner manufacturing cycle.

3D dental model acquisition

All dental scanners that allow the export of 3D mesh dental scans can be used to capture teeth and gum data from patients, but as Zimmermann et al. reported in a 2010 JADA article, certain scanners perform better in full-arch scans than others. Several other factors will also help dictate what is considered an “ideal” scanner for a practice. The most common factors include:

  • The initial financial investment required to purchase the scanner and a dedicated computer.
  • Cost of consumables such as scanner sleeves.
  • Annual subscription fees.
  • Available training and support services.
  • Available software packages.
Trios by 3Shape, iTero by Align Technology and Medit are perhaps the common scanners. Most practices start with one scanner and gradually transition into a second and third scanner as their digital services expand. It would be practical to keep multiple scanners on the same brand for the consistency of patient experience, training, inventory and the scan files database.

In an IOA system, scans will be prepared locally by a practice team member before designing the tooth movement. The quality of 3D meshes significantly affects the quality of appliances fabricated from these scans. Practitioners are encouraged to develop a scanning best practices guideline (Table 1) to minimize poor-quality scans.

Fit to Print (Part 1)
Table 1: Scanning best practices.

Aligner digital software packages

Digital software packages for an IOA system have been expanding in the past few years. Certain software suites provide features such as digital indirect bonding as well as aligner therapy. The packages offer three processes:

  • Preparing mesh models and segmenting the teeth.
  • Developing a digital therapeutic treatment plan, including the biomechanics and choice of aligner auxiliaries.
  • Generating 3D printing-friendly 3D dental models.
Maestro 3D, uLab Systems, 3Shape Aligner Studio and SureSmile are examples of digital platforms one can use for an IOA system. The most common pricing models for these software packages are either charges per digital model export or charges per case treatment.

The cost associated with this software is only one aspect that a provider should assess when evaluating various choices on the market, however. The time spent in each step, starting with importing a dental model to exporting a file ready for 3D printing, is another critical factor when selecting the optimal platform for your practice. Besides the workflow to create models for aligners, auxiliary features such as attachment varieties or pontic protocols should also be evaluated.

In sum, the “ideal” aligner digital software will vary by clinic. One should clearly spell out the practice needs before comparing these software packages (Table 2).

Fit to Print (Part 1)
Table 2: A checklist to help identify and rank the ideal aligner software platform for your practice.

3D printers

Desktop 3D printers have become more affordable and easier to operate. Additive manufacturing has been significantly adapted in certain fields, including dentistry and medicine; orthodontics has integrated it before many other sectors of dentistry.

3D-printing dental models to thermoform the aligners is a critical step in the aligner manufacturing cycle. This step can become a bottleneck and add stress to the daily operation in a practice.

A common question about 3D printers is, “I finally decided to start 3D printing. Which printer do you recommend?” Before we dive deep into information on desktop 3D printers, let’s look at the four core attributes of an in-office 3D printer. An optimal one should work well with these four main concerns:

  • Reproducibility: It should print accurate parts at 95% success rate when calibrated.
  • Print time: It needs to match the weekly demand of a practice.
  • Adaption learning curve: It should require only reasonable levels of maintenance and training to operate.
  • Economics: Its cost of operation must be reasonable, too.
Someone’s printer of choice will change based on the priority ranking of these attributes. For example, a practice that will create 100 models per week might opt for a different printer than a practice that needs only 10 models per week on average.

It is important to mention that the initial cost of 3D printing adaption is often a primary driver in choosing a printer. With multiple options on the market, it doesn’t make sense to spend more than $10,000 on a 3D printer at this point.
Author Bio
Dr. Rooz Khosravi
Dr. Rooz Khosravi is a clinical assistant professor at the University of Washington and speaks on implementation of in-office aligner systems and 3D printing. Khosravi also established the Digital Orthodontics Hub, a study club that offers training courses on digital orthodontics. In addition to private practice and academic life, he is an orthodontist-scientist consultant at uLab Systems, SprintRay and Bay Materials. In these capacities, he assists with accelerating the development of advanced software and materials for digital orthodontics.

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