Dr. Perry E. Jones with intraoral scanning device.
Advances in dental technology continue to improve patient comfort, shorten treatment times, and improve the efficiency and accuracy of the restorative process. The messy, unpleasant experience associated with taking impressions is no longer a given. Today, intraoral scanners can take a full spectrum of digital impressions ranging from single unit cases, to multiunit restoration to full arch scans to implants.
In 2005, after searching for a solution to eliminate the “goo” and mess of impression taking, I was the first dentist to fully integrate iTero digital scanning into everyday dental practice. The “digital” impressions captured by intraoral scanners have been used for years to create the models used by dental labs but producing models to support traditional laboratory processes does not fully leverage the possibilities of digital dental impressions. Creating restorations completely without physical models was a next logical step. The principle was simple enough, but producing the full range of restorations without a physical model, required a dental laboratory partner adept at spatial data processing, CAD/CAM additive manufacturing (AM) and design verification.
Advances with in-house milling technology now allow intraoral digital scan data to be sent directly to my CAD software, and design a crown in minutes. The digital data in STL format is then sent to a milling unit capable of milling lithium silicate, lithium di-silicate and even pre-sintered zirconia. The milling times are now reduced such that we are able to produce a crown in an hour, from prep start to design to mill to final delivery.
AM is a key component of the digital restorative process. It provides a bridge between the physical and the digital representation of patient data. Once the digital impression has been taken, it can be used anywhere in the restorative process in a variety of applications, such as production of surgical guides, investment patterns, try-in prostheses, temporary/provisional prostheses, denture moulds, and laboratory working models.
3D printed models have many applications in dentistry particularly in the world of thermoplastic appliances made via vacuum forming or direct press down of heated thermoformed materials such as bleaching trays, retainers, athletic mouth guards, orthodontic appliances and so on. These appliances were made in the past on gypsum models that were very fragile, only single use and inaccurate. We have left the ”Stone Ages” of gypsum for highly accurate, virtually unbreakable, multiple-use, 3D printed models.
Some four years ago I began using a Stratasys Objet 30 printer in my office for everyday modelling using MED 690 polymer and MED 610, an FDA approved material to manufacture surgical guides. The world of surgical guides has undergone tremendous advances.
Our surgical guide workflow is as follows: We take a Cone Beam Computed Tomography (CBCT) using Mobile Imaging Solutions, a service I developed that provides onsite imaging using the latest lowest radiation dose mobile system to produce the DICOM data that will be file merged with highly accurate STL files from an iTero Element intraoral scan. That data is merged using 3shape Implant Studio 2016 software. This creates a virtual planning platform to design the location of the implant restorations as well as precise location of the implant in bone. Further, we can design the immediate screw retained pre-made provisional restoration that will be placed at
the time of implant placement with the surgical guide. AM is used to produce the highly accurate surgical guide in a 100% digital workflow.
AM extends into everyday dentistry with orthodontics where mass customisation allows products such as Invisalign to manufacture aligners. We are now able to replicate the process in our office. Tooth movement can be easily performed virtually using in-house software to segment a series of stages, STL files are used to 3D print a physical model of each stage and on this physical model a thermoplastic appliance is created. These sequential clear plastic aligners are then used to create precise tooth movements.
The future is bright for AM in everyday dentistry. The efficiencies and improved dental care afforded by technological advancements can only continue to improve the speed and quality of dental treatment. 3D printing enabled by intraoral digital scanning is the next paradigm shift, offering dentists, the opportunity to move beyond traditional methods into a new world of digital dentistry.
Bio: Perry E. Jones, DDS, MAGD, IADFE Associate Professor, Adjunct Faculty, Dept of Oral Maxillofacial Surgery Associate Professor, Adjunct Faculty, Dept of General Dentistry Virginia Commonwealth University, School of Dentistry.