Diagnostic Records:  Bridging the Analog – Digital / 2D – 3D  Divide

By Dr. Kenneth Webb

Your first patient after lunch is coming in for a second opinion consultation and bringing in diagnostic records from another orthodontic office.  Consider the following scenarios:

  1. The patient hands your front desk staff a box and an envelope. The box contains a set of plaster study models.  The envelope contains two radiographic films (a panorex and a lateral cephalogram) and a printed sheet with intra and extra oral photographs.
  2. The patient hands your receptionist an envelope. The envelope contains four pieces of paper. Printed on the sheets of paper are the following: intra and extra oral photographs, an image of a panorex, an image of a lateral cephalogram and a picture of a screenshot montage of digital study models.
  3. The patient hands your new patient coordinator a disk. The disk contains several digital files.  Among the files are several JPEGs (digital intra and extra oral photographs), two STL files (3D digital study models with centric occlusion bite registration) and one DICOM file (a large field of view CBCT scan).

What happens next depends on your level of familiarity with digital technologies and which orthodontist’s diagnostic records were presented by the patient.  Another question is whether or not the three different sets of diagnostic records satisfy the AAO’s Clinical Practice Guidelines for Pretreatment Unaltered Diagnostic Records – a full PDF of the Guidelines can be found on the AAO Member Website (Clinical Practice Guidelines).   It is my opinion that in order to best serve our patients, we work to establish guidelines to bridge the analog-digital / 2D – 3D divide and create a standard for maintaining, sharing and transferring both analog and digital diagnostic records.

Where do we start?  Analog diagnostic records (plaster study models / radiographic films) seem fairly straightforward: maintain/provide the originals or a satisfactory copy.  Digital diagnostic records are a different story – 2D or 3D – different manufacturers and different software may format the data files into formats that are incompatible with each other.  For guidance, I turned to the medical community, where digital imaging has been commonplace for decades (Digital Radiography, CT Scans, MRI).  A review of the literature (Exchanging and Sharing Medical Images) provided two important considerations: the imaging files should be the original unaltered files and should be provided in a vendor-neutral format.  We didn’t learn about this in our residency programs!

What’s next?  We already discussed analog diagnostic records.  Here’s my opinion on digital diagnostic records. I feel the original unaltered image files should be handled as follows:

  • Intra / Extra Oral Digital Photographs: Should be provided in a JPEG ( .JPG ) file format.  This format is ubiquitous.  You can view this format on your phone or your office workstations.  All imaging software programs will accept photographs in this format.
  • 2D Digital Radiographs: Should be handled the same as digital photographs: JPEG format.  All imaging software and practice management software should have the capability of exporting and importing digital radiographs in JPEG format.
  • 3D Digital Radiographs (CBCT Scans): The original unaltered DICOM ( .DCM ) files should be provided.  The scan data may be exported as a single .DCM file or as a sequence of multiple (hundreds) .DCM files.  All of the major CBCT scanner manufacturers package their scanners with software that can import / export scan data in this format.  My thoughts on accommodations for a non-3D orthodontist’s use of the DICOM dataset will follow.
  • 3D Digital Study Models: The original unaltered intra-oral scan should be provided in STL ( .STL ) file format.  Typically, the Digital Study Models will be exported from the software as two files that contain the upper and lower models plus a bite registration.  Most major 3D intra-oral scanners contain in their accompanying software the ability to convert and export the raw scan data as an STL (vendor-neutral) file set.  If you own a 3D intraoral scanner that has “closed architecture” and cannot export the scan data in STL format, it is my opinion that you should provide a 3D printed set of study models if asked.  The requirements for diagnostic models in the AAO Clinical Practice Guidelines are clear:  they must be 3 dimensional to suffice.  In my opinion, a printed screenshot of digital study models does not meet these requirements.  There are other considerations in handling digital study models (i.e. open shell/surface scan versus closed shell); however, I feel these are beyond the scope of the current discussion.

Now we must consider how all orthodontists, from non-digital to fully 3D digital, can utilize each other’s diagnostic records.  Let’s look back at our scenarios:

  1. The diagnostic records presented in scenario #1 above do appear to fulfill the requirements in the Clinical Practice Guidelines, except that I would like to see the photographs provided in digital JPEG format as opposed to a printout. If the photographs are indeed “photographs,” I have no advice – except to grab your digital camera, cheek retractors and mirrors.  If you receive these records and feel additional information or imaging is required to provide an accurate diagnosis and treatment plan – that is your (and the patient’s) choice.
  2. In my opinion, the diagnostic records presented in scenario #2 do not fulfill the requirements. Diagnostic models need to be three dimensional – a printout is not.  Regarding the other printed pictures – see my recommendations above.
  3. The disc presented in scenario #3 does, in my opinion, fulfill the requirements. The problem is that a non-3D orthodontist is likely unable to utilize or interpret most of the diagnostic information provided.  How then do we bridge this divide?

In my office where we utilize 3D intra-oral scanning and ultra-low dose CBCT scans, the diagnostic records process is fairly quick and relatively non-invasive.  I’ve yet to have a patient say “I’d rather have an impression” after a 3D intra-oral scan.  I have previously blogged about my opinions on ultra-low dose CBCT scanning (AAO Tech Blog).  I understand that not all orthodontists can utilize, or interpret, the data we produce.  When asked to provide a copy of a patient’s diagnostic records, we produce a disc that contains the following files:

  • Intra and extra oral photographs in JPEG format
  • 3D Diagnostic models – original unaltered – in STL format
  • CBCT Scan – original unaltered – in DICOM ( .DCM ) format: this allows another orthodontist to import the scan data into their own 3D viewing software
  • CBCT Scan – with viewer – provided as a separate proprietary file type: this allows another orthodontist (without their own 3D viewing software) to view the scan data
  • Panoramic view – reformatted as a JPEG file
  • Lateral Cephalogram – reformatted as a JPEG file – with distance ruler for tracing purposes

In my opinion, the disc we produce fulfills the requirements for “Pretreatment Unaltered Diagnostic Records,” and as provided, can be utilized by any orthodontist for diagnostic and treatment planning purposes – with one exception:  the STL files.  If physical study models are requested, the STL files should be printed and provided.  Keep in mind most jurisdictions allow for a nominal copying or duplication fee to be assessed to a patient who requests a copy of their records – the 3D printing charges should fall into this category.

The Committee on Technology will be presenting recommendations to the AAO Board of Trustees in the coming months to aid in amending the Clinical Practice Guidelines in regards to Diagnostic Records, Record Keeping and Transfer of Orthodontic Patients.  My thoughts will be a part of the conversation.  It is my opinion that one day, in the not too distant future, our diagnostic records will be all digital and all in 3D.  As this transition continues, I feel we must take steps to bridge this 2D – 3D / analog-digital divide in a manner that is in the best interest of our patients and within the skillset of every orthodontist.

I ask for your comments and suggestions on this topic.  CTech wants to make sure that all AAO Members are represented in the process as our specialty moves forward with advances in technology.


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