ClinCheck® as a Tool for Therapeutic Diagnosis

By Dr. David Paquette

The second article in a series, detailing the use of Invisalign® in complicated, comprehensive treatment.

Article 1

 

To provide orthodontic treatment using Invisalign , the orthodontist must become familiar with the software provided by Align Technology. This software is called ClinCheck and when used properly, ClinCheck® is more than a movie of the virtual setup. ClinCheck® is the bridge between the virtual world and the real world…that is, ClinCheck® is the interface used by the orthodontist to visualize his or her proposed treatment in all respects prior to ever delivering the first Aligner . It is the tool the orthodontist uses to communicate with the technicians in Costa Rica to design and execute the doctor's treatment plan for a given patient. ClinCheck® is a 3D virtual representation of all aspects of the anticipated treatment. ClinCheck® allows the orthodontist to evaluate projected final tooth positions, amount of individual tooth movement, arch symmetry, rate of tooth movement and within reason, even the duration of treatment.

The Digitization Process

Let's begin with the digitization process. Treatment success begins with a high quality polyvinyl siloxane (PVS) impression. Initially Align Technology used a process called destructive scanning to produce the 3D digital image of the patient's teeth. It involved pouring the impressions with plaster to produce a physical 3D model in the same way we would normally make study models in our office. Those models were then "scanned" using a destructive technique whereby the model was photographed from the occlusal view, milled down slightly (1/4 the height of a sheet of paper), photographed again, milled down some more, photographed again, etc. When process was completed the computer software would then use the series of digital photographs to reassemble the layers and recreate the model virtually by stacking the images. The destructive scanning method had the advantage that a lab technician could fix minor imperfections in the impression by repairing the model prior to scanning. The disadvantage was that it was expensive, and time consuming (additional 2 weeks processing time). Align no longer uses the destructive scanning technique, but rather when the impression is received by Align it is converted directly into an electronic model by means of a Computer Aided Tomography (CAT) scan. Because of this, plastic impression trays must be used and there is no plaster model intermediary on which a lab technician can clean up blebs or repair defects. The impression must be perfect.

Impressions

The impression technique that I use involves a two-step process. The first step involves making custom trays and training aligners. When the patient elects to move forward with treatment, an alginate impression is made of both arches. The patient is then scheduled to return for final impressions. The rest of the first step is completed in the lab. The impressions are poured up in our office in standard dental stone and trimmed as though they were to be used to make Essix style retainers.

 

Figure 1. Initial stone models

 

Then the thermoplastic material is formed over the models but not trimmed.


Figure 2. Models with thermoplastic material in place

 

While the full sheet of thermoplastic material is still on the stone model, a plastic impression tray is sized and then filled with the heavy body or putty PVS material of your choice (we currently use ESPE Penta Quick, a relatively inexpensive PVS alginate substitute) and the model with untrimmed thermoplastic material is inverted and pressed down into the impression material. The reason for pressing the model into the impression material and not vice versa is to assure good visualization to produce a consistent thickness of impression material around the teeth creating a perfect custom tray. It is important to make sure the distal of the second molars are captured in the custom tray.

 

Figure 3. Plastic impression trays with heavy body material

 

Figure 4.  Models with thermoplastic sheet inverted into heavy body material

 

 

 

 

Figure 5.  Completed custom trays

 

Once the custom tray is made, the thermoplastic material is trimmed like a typical EssixÒ style retainer and will be used as the patient’s “training aligner”.

 

The next step involves the final impression.  The patient returns to the office at which time the final PVS impressions are made by placing the minimal amount of a fast set light body wash inside the custom tray.

 

Figure 6.  Custom trays with light body wash ready for final impression

 

 

Figure 7.  Completed final impressions

 

 

Once the impressions are made, the patient receives the training aligners and some bleach if they are interested in bleaching their teeth while they await the arrival of active aligners from Align.

 

 

The Virtual Setup

 When the impressions arrive at Align Technology in Santa Clara, California, they are scanned using a CAT scan to produce a 3D virtual model.  The technician uses the intraoral photographs provided in the submission kit to articulate the models.  The occlusal registration sent in with the impressions is used only to verify the occlusion if the photographs are of poor quality.

 

Figure 8.  3D Virtual Models Generated from CAT Scan of PVS Impressions

 

 

Once the virtual models are produced they are then sent electronically to Align’s facility in

Costa Rica where they are sectioned using boundary recognition software to define individual teeth.  It is important to remember for future discussion that the impression does not capture the interproximal surfaces of the teeth which means the software interpolates that information and estimates where the surfaces and contact areas are.  Once that is accomplished, virtual “roots” are placed.

 

Figure 9. Tooth separation

 

The technicians recreate the virtual gingival margins using morphing-type software to mimic the gingival conditions seen on the clinical photographs.

 

Figure 10.  Gingival Contouring

 

The preparation work is finished at this point and the virtual model is forwarded electronically to the TREAT® operator to perform the virtual setup and staging.  TREAT® is the proprietary software that Align Technology uses to simulate treatment and set up the virtual model to allow the manufacture of AlignersÒ.  It is a sophisticated 3D graphics program that gives the operator great control of tooth position as well as rate of tooth movement.  It is not the software that the orthodontist uses to view the virtual model. 

 

ClinCheckÒ

 

The software used by the orthodontist in their office is called ClinCheck® (figure 11).  ClinCheck® allows the orthodontist to view the treatment in all aspects as well as superimpose one stage of treatment over another to visualize individual tooth movements in order to gauge the probability of accomplishing the desired movement.  After all, while the computer can move teeth anywhere, that does not mean that the patient will actually respond that way biologically.

 

Figure 11.  Screen capture of ClinCheck 2.0 ® user interface

 

The single greatest benefit of ClinCheck® is its usefulness as a tool for therapeutic diagnosis.  One can prescribe a given treatment plan, say non-extraction with some expansion and proclination on a crowded case, and evaluate the outcome prior to ever initiating treatment.  That option can then be compared with treatment using either extractions or interproximal reduction (IPR).  Although the treatment outcomes cannot be superimposed, they each can be superimposed on the pretreatment virtual model for evaluation (figure 12.).

 

 Figure 12.  Superimposition tool showing initial in blue and final in white.

 

 

 The superimposition tool is only one of the many tools available to the orthodontist for evaluation of potential treatment outcome.  I will outline the use of each of these tools with examples.

The first group of tools is the group of virtual model manipulation tools located in the upper left of the screen (figure 13.).  Align has provided the orthodontist with several ways to manipulate the virtual model.  The first is to simply left click on the model and manipulate the view with your mouse.  Some people have a little difficulty controlling the movements using this method.  The next method is the defined views (figure 14.).  The defined views allow one to simply click on a predefined viewing angle of the model or proceed through a sequence of views (figure 15.) to allow thorough examination of the final occlusion and alignment.

 

Figure 13. Virtual model manipulation tools

 

 

Figure 14.  Predefined views available by one click

 

Figure 15.  Predefined views available in sequence (note Anterior currently selected)

The next tool available is the gallery views, which allows the orthodontist to view a single model, two arches simultaneously in separate orientations or a collage of six separate views.

 

 Figure 16.  Gallery Views

 

 

Moving down the left side of the interface there are a group of four navigation buttons that allow the user to move the model around the screen, zoom in or out overall, rotate the model or zoom into a specific location by clicking the mouse on the desired spot (figure 17.).

 

Figure 17.  Navigation Buttons

 

Below the navigation buttons are a group of three wheels that allow the user another method of rotating the model in any plane of space.  Immediately below the navigation wheels is another zoom tool that allow the user to either gradually increase or decrease the size of the model or simply type in the amount of magnification desired (Figure 18.).

 

 Figure 18.  Navigation Wheels and Zoom Control

 

Continuing down the left side is a group of resolution and illustration buttons.  These allow the user to increase or decrease resolution (lower resolution allows faster computer operations).  They also allow one to show or hide the upper model, attachments, tooth numbers, interproximal reduction instructions, comments, lower model, virtual pontics, superimposition, grid tool, and overcorrection stages (Figure 19.).  These buttons function in an on-off manner simply by clicking the mouse on the desired button.  It should be noted that the default setting is for IPR prescription, attachments and comments to be turned on initially and for the tooth numbering, superimposition and grid tool to be turned off initially.

 

Figure 19.  Illustration buttons

 

 

An example of the grid tool is shown in Figure 20 below.  Note that the widget in the lower right allows the manipulation of the grid orientation, the scale of the grid can be changed as needed and the navigation wheels can manipulate the overall position of the model and grid together.  This is a great tool to evaluate symmetry, arch form, spacing for implants or veneers, actual amount of expansion or intrusion, etc.

 

Figure 20.  Grid tool superimposed on occlusal to check symmetry

 

 

Finally on the lower left is a drop down menu of tools for adjusting the grid characteristics, capturing screen shots or making an AVI movie of a specific view of the ClinCheckâ (note that this is not interactive, but rather is a movie that is only viewable in the orientation in which it is captured).

 

Moving to the top center of the screen is the interproximal reduction (IPR) recommendations.  The process of IPR will be discussed in a future article.  The default view is for IPR recommendations to be turned on so that if any is required it automatically appears unless the user turns it off.  The instructions are very clear about when and where IPR is to be performed (Figure 21).

 

Figure 21.  IPR Recommendations

On the right side of the screen is the comments section.  Comments are displayed in two colors, one designating the comments entered by the orthodontist and the other designating comments entered by the TREAT technician.  The comments are displayed as the default setting although the orthodontist can click the double arrow tab at the top of the bar next to the InvisalignÒ logo to view the virtual setup in a larger mode and hide the comments.  Having the comments viewed at the same time as the virtual model is very helpful in enhancing communication between the orthodontist and the technician (Figure 22).

 

Figure 22.  Comments Section

 

 

The last section is in the lower right of the screen.  This is the tab to either modify or accept the setup.  When modifying the setup, first comments are added then they are submitted.  This allows the orthodontist to add comments at different sessions and then submit them all at one time (Figures 22 and 23).   When accepting the setup, there is a confirmation screen intended to avoid accepting a setup by mistakenly clicking the wrong button (Figure 24 and 25).

Figure 23.  Modification Comments Added

 

 

Figure 24.  Comments Submitted (note: click on the yes tab to modify)

 

 

 

Figure 25.  Case Acceptance Verification

 

Summary

 In summary, ClincheckÒ is an incredibly powerful tool for therapeutic diagnosis.  It allows the orthodontist to view treatment in every aspect from beginning to end and plan for problems before they ever occur.  Like most things in life, it is only as powerful and the user makes it and the more comfortable and familiar one is with the interface the more likely one is to use it to the fullest extent possible.

 

Dr. Paquette graduated from UNC School of Dentistry in 1979 with a doctorate of Dental Surgery. He received a Master's degree in Pediatric Dentistry from UNC in 1983. His Master's thesis won a national research award that same year. He is board certified by the American Board of Orthodontics and the American Board of Pediatric Dentistry. He served as consultant in Pediatric Dentistry for the United States Air Force in Europe and Asia until 1987. In January of 1990 he received his Master's degree and specialty certificate from St. Louis University. Since 1990 he has been in private practice in Charlotte, NC. Dr. Paquette won the coveted Milo Helman Award in 1991 with his Master's thesis and has since gone on to achieve numerous, prestigious honors in the field of Dentistry and Orthodontics. In addition, Dr. Paquette has carried out several Academic appointments within St. Louis University, Carolinas Medical Center and UNC School of Dentistry. He has published numerous articles in many different industry publications and is a frequent speaker both in the United States and Worldwide, teaching Orthodontists current techniques as well as practice management skills. Dr. Paquette is passionate about advancing the art and science of Orthodontics. He enjoys spending time with his lovely wife Jenny and their 4 girls and when time permits he likes running, scuba diving, water and snow skiing, snow boarding and being an instrument-rated private pilot.