So, you've made the decision to purchase a multimodality
machine (MMM) to expand your practice.
That's the easy part. Now, how do you go about
choosing the right unit for your practice?
In our practice, we looked at many models and
we developed a three-part process to make a thorough
evaluation. I like to break it down into three areas: the
imaging machine, machine programs, and software
1. The Imaging Machine
Space Foot Print - If you have an existing office
or are building a new office, it has to fit in different
ways. Machines have three requirements: a physical
space, minimal operational space and an accessibility
If you have an existing office, stand-up machines
will have a smaller physical space requirement. The
minimum operational space is the least amount of
space for the machine to operate while taking an
image. The machine might fit, but the head has to
rotate. Accessibility space is often overlooked. Not
having good accessibility limits your patient population.
Sit-down machines have a disadvantage of
transferring the patient from a wheelchair or other
mobility device, requiring more space. A stand-up
machine should have the flexibility to be lowered
to the height of a wheelchair. Many elderly patients
have dropping head syndrome and are more comfortable
in their own wheel chair or a small chair.
Flat Screen Technology - This is your X-ray sensor
or film onto which the image is projected. Image
sensors fall into two categories: image intensifiers and
flat panel detectors (FPD).
Flat panel detectors are the next generation in
digital technology. They are sensitive and fast, and
last longer without any replacement or calibration.
Image intensifiers (like CAT scans) need to be serviced and imaging might diminish over time. Some
machine companies offer service contracts on image
intensifiers for future issues.
2. The Machine Programs
The available machine programs are the bread and
butter of treating a diverse patient population and
expanding your practice.
When deciding on a 3D image, think about
your field of view (FOV), or how much you want to
see and accomplish in your practice. Next, think
about your regions of interest and areas you would
like to diagnose.
Pain Diagnosing - A patient comes in with diffuse
pain on the left side of the face. If your machine
is limited to only a small volume size (3x4), 8-12mS,
you would need to take multiple volumes to capture
the whole side. If you took three additional small volumes
to get the unilateral side, you are now at an
average of 32-48mS. For our endodontics practice, we
prefer a medium FOV 8x8 or 4x8, but having the flexibility
to go smaller. For pre-screenings for diagnosing
pain or medical clearance (oncology, orthopedic, cardiac),
a small volume only 3x4 FOV was not practical.
Too many scans, and separate volumes to open, copy,
study or transmit.
Implantology - For the growing practice, a bilateral
FOV is more advantageous for treatment planning
and more cost effective for the patient. Having
a single bilateral scan reduces the amount of scans,
radiation, and time to the office and patient. Surgical
guides crossing the midline are needed to place bilateral
implants. A small-volume-only machine means
more surgical guides, increased office time and
increased cost to the patient.
Panorex - Look for a MMM that has the ability
to take both two-dimensional (2D) panorex and
three-dimensional (3D) imaging. Pay close attention
to what you are actually purchasing. If you are purchasing
panorex in a MMM, make sure it is a real
panorex. Make sure you can utilize and bill for it. A
panorex, CDT code D0330, is based upon the image,
and the science behind it. Based on the principle of
the reciprocal movement of the X-ray source and an
image receptor around a central plane, in which the
object is located giving us a 180-degree from ear to ear
consisting of both maxillary and mandibular arches.
A 3D cone beam machine can reconstruct a 2D
image using existing data from a 3D scan (Fig. 1).
This image is CDT code D0362, a slice layer taken
from the 3D volume (Fig. 2). Many insurance companies
do not pay for the latter if you submit that
image as a panorex image, hence, insurance fraud.
Panorex programs and images can be very
sophisticated for diagnosis with the right technology
behind them. A segmented panorex program provides
variable regions of interest and a lower radiation
dose. The Planmeca panorex has a Smart Pan
feature. It can calculate nine serial image layers with
a 2mm shift. So, do your homework, and see what
beneficial features a MMM may offer and determine
how it will benefit your practice.
Extraoral Super Bitewing - When looking for a
MMM, this is a must! Actually, it is a must for any
practice. In less than eight seconds, the image is
obtained in one extraoral exposure with a low radiation
dose. No overlap and geometric distortion. Look
for a MMM with this feature. This makes treatment
and diagnosing of children, gaggers and compromised
patients simplistic. Your staff and patients will
thank you (Fig. 3).
TMJ Programs - Studies
have shown that clinical assessment
of TMJ disorders is often
inconsistent with joint imaging
studies. A wide variety of
issues - osteoarthritis, remodeling,
and fracture - can have different
modalities of treatment. Look for uni and bilateral
TMJ programs in a MMM in both 2D and 3D
imaging. In a 3D program make sure the FOV is sufficient
enough to encompass the entire joint.
Implant Program - What to expect in an
- A preloaded implant library
- Easy manipulation of the implant in all directions
from one screen
- Accurate measuring tools
- Mandibular canal tracing
- The ease to export and import from thirdparty
- Hounsfield scale
- Third-party integration
All are important software features that make
your treatment planning more proficient.
Airway Program - Symptoms of obstructive sleep
apnea, mouth breathing and chronic sinusitis are
disease processes that can perpetuate problems in the
oral cavity. Having a proper appliance and working
in unison with the proper physician provides the
patient with more comprehensive treatment. Patients
prefer an image to be done right in the office. It is less
costly, more convenient, has significantly less radiation
dose compared to a traditional hospital, and
patients tend not to get lost in the referral process.
Stitching Programs - A stitching program
allows you to take two or three consecutive volumes
and sew (stitch) them together to give you a larger
volume. A stitching program should be a standard
program with every machine. A good stitching program should have the versatility to do horizontal and
vertical volumes. Depending on the software, the total
image may be smaller and at a lower resolution.
Always ask to see a few stitched volumes when comparing
images from different machines. If you think
you will be doing this often, you need a machine with
a larger volume that has the flexibility to take smaller
volume without losing resolution (Fig. 6).
3. Software and Support
Software is the heart of your detail and imaging.
Look for the companies that have good Research and
Development. Ask how many upgrades have accrued
in the last two years. Look to see the difference between
the older and newer programs.
Artifact Removal Program (ARP) - This is one
area many companies do not talk about that I feel is
very important. Artifacts are the white streaks produced
in the image by dental metals. These include
amalgam, gold, restorations, PFM crowns, implants,
gutta percha, metal posts, bone screws and orthodontic
brackets. An algorithmic math equation is
used to smooth out the artifacts, to make the image
look clearer. Algorithms are not selective! Many
machines run the ARP automatically and give no
option of a raw volume without it. If you don't see
many fracture lines, there is a good chance the lines
were removed by the pre-programmed ARP. Fig. 7
shows a fracture line before and after the ARP was
implemented. Look for a machine that gives you a
raw volume and the option to run the ARP. Ask your
sales representative for scans with a variety of restorations.
Also, ask for cases with small fractures that you
can compare 2D and 3D on the same tooth. Ask for
at least five patient scans to see how the machine
handles the issue.
Radiation Dose - This is like doing your taxes; it's
confusing, with multiple answers. When told that a
machine has the claim to lowest radiation dose, prove it!
It is very difficult for one machine to have the claim of
the lowest dose. There are too many variables that go
into taking an image. All machines are very different! So
what did we do? Our practice chose a MMM that gave
us future versatility! The unit we chose gave us the
option of 16kVs and 16mAs. Many machines lock you
into a standard mA and a few kV adjustments. In time,
as the flat panel sensors and software improve, you will
have the option to use less radiation without an expensive
upgrade or changing your machine! Patients may
look to this direction as 3D imaging evolves in dental
practices. Look for companies that plan for the future,
it becomes a cost savings for your office.
Voxel Size - Having the smallest voxel size does
not mean you will have the most diagnostic image.
Some determining factors in resolution are:
- Voxel size
- The software's ability to interpret the data
- The software's ability to minimize the noise
The voxel is a 3D pixel in which the resolution of
a 3D image is determined. In theory, the smaller the
voxel size the better the resolution. But, smaller voxel
size gives you more noise and higher dose of radiation.
It is similar to looking though your surgical
microscope at the highest magnification, it is grainier
and difficult for your eyes to interpret the image.
Look to a solid company having good Research and
Development for future improvement to the software
and its interpretation of the data.
Image Variation - Volume size is one aspect we
have talked about. Having the flexibility to do various
size volumes has a large advantage. What about patient size? A child, teenager and linebacker will
not all have the same jaw shape. Jaw size can vary in
shape. Shapes can vary from triangular to U-shape.
Having a variety of jaw shapes and volume size
allows for more image flexibility for rendering a volume
Operating Software System - The brains
behind your image tell the machine how to render
the image, how to process the image, and how to
deliver the image.
Upgradeability - There are two aspects to this
that are very important: the machine and the software.
Maybe you can't afford all the bells and whistles
yet. A reliable company will be able to upgrade
you from the panorex to whatever degree of 3D that
you feel comfortable with on the same machine. Yes,
without putting a new machine in and at a nominal
cost. Don't be afraid to ask for comparative pricing.
Make sure the company has a history. Second, just
like when your cell phone automatically upgrades its
software, so your operating system should be
upgraded. Get a good history. Ask questions. How
many upgrades have been done in the last few years,
and is there a cost? Ask to physically see the difference
in the programs. What about future integration
and third-party programs? The way technology is
moving you will be able to plan your patient's whole
treatment plan right from your computer.
Is third-party programming already integrated or
can they be easily integrated into your programming,
Dolphin, Materialise, etc.? It makes your life
simpler (Fig. 9).
DiCom imaging should be a staple. It is universal
and the quickest way to send via the Internet. Your
machine should be able to send and easily import.
If you use a Mac or PC, make sure that your operating
system can do both. Technology changes and is
hard to predict what the future holds; better to have
the flexibility at your fingertips.
Window versatility is something one does not
think about when purchasing a machine:
- How easy is it to manipulate and study your images?
- Can you stay in the same operating window or
do you have to go to another window to view a
- How fast is your response time?
Secondary Equipment and Support - You purchased
the unit, now what? What is included or
- Computer equipment
- Reconstruction PC
What about the warranty? How long is the warranty?
Are there any service contracts? Who is responsible
for fixing the computer or the unit? Does the
repair technician live local or three states over? Phone
support is crucial! Support should come from the unit
company and the dental supply company. Look for
established companies. Companies that are sold and
resold may lack in Research and Development.
Do your homework. Decide what you need and
expect from your machine. Ask for references of the
last 10 sales. Ask for five patient volumes to manipulate
at home on your computer. Choosing the right
multimodality machine and company is a one-time
investment to enhance your practice.
Now, you may ask, which unit did we choose? The
Planmeca ProMax 3D, for all the reasons discussed.