Seven rules for the successful use of IOR with implant-based restorations
Chandur Wadhwani, DDS
Radiography plays an integral
role in the planning, surgical and restorative phases of dental implant
therapy. It has also been used to follow the “health” and measure long-term
success of these medical devices.
A well-made radiographic
image (film or sensor) can give lots of information about what is occurring, but
as with any diagnostic tool, it is not without limitations. These should be
clearly understood by the clinician so that information received can be
properly acted upon.
can only be confirmed with light microscopy sections,and cannot be confirmed by
Radiography simply gives an
indication of bone-to-implant contact, which for most offices is restricted to 2-dimensional
imaging even though the site is 3-dimensional.
As a guide, it should be
understood that limitations exist when reviewing bone-to-implant contact on a
radiograph. Studies report that uniform gaps of up to 100 microns between the
implant and surrounding bone sometimes go undetected, even when experienced
clinicians are reviewing the images.
site information prior to restoration is extremely useful.
The implant and the adjacent
sites can be evaluated for any pathosis, implant positioning, angulation and the
best path of restoration insertion. Radiographs can reveal bone quality and
quantity and various bone patters can be highlighted by IOR images.
This is important as implants
are commonly placed in alveolar bone, which may have large marrow spaces that
could impact the way we restore the implant. This is well understood in other
areas of dentistry (e.g., endodontics). Marrow spaces provide an easy escape
route for cement, which can sometimes be observed around implants when
cementing a crown.
angulation is everything.
When confirming how
components fit, IOR can be indispensable, especially for sites that cannot be
directly visualized or accessed with explorers. With the implant more than 20
degrees off the incident X-ray beam, the mismatch of components becomes almost
impossible to detect. When the angulation error is closer to 5 degrees or less,
the components can be confirmed to fit to within 50 microns or less. As a
general rule, when reviewing radiographic images, the clearer the screw thread
pattern seen, the closer the incident X-ray beam is to perpendicular to the
radiographs intended to monitor marginal bone levels must be standardized.
requires establishing a consistent method of holding the radiographic sensor
(or film) and the incident beam at 90 degrees to the implant’s long axis, each and
every time the image is produced. Remember, when a 2-dimensional image is made
of a 3-dimensional site, angulation grossly affects what is identified in the
image due to beam projection.
Interestingly, most studies
on bone loss around implants fail to achieve standard, reproducible images,
making comparisons between serial images just about meaningless. Note that
sites adjacent to the implant offer clues to angulation errors. Radiopaque
crown margins that change shape on nearby teeth are frequently a giveaway of
your implant system and how the mechanical union of the parts you are working
with appear on a radiograph.
Because certain system
components have flat matching surfaces, errors in attachments can be easily
detected when the radiographs have been taken 90 degrees to the incident X-ray
beam. Non-flat, internal tapered systems may appear very different to their flat-top
counterparts. By assessing the screw dimensions carefully, the clinician will
readily understand if the components match well and are seated correctly.
a cement-retained implant restoration with inaccessible margins, use IOR to
locate possible residual excess cement that may cause future problems.
Use a cement that can be
clearly identified on a radiographic film. Many cements show up poorly, thus remaining
undetected, which could impact the future health of the tissues supporting the
implant. As a general rule, choose a cement with minimum radiopacity equivalent
to 3mm of aluminum (which is the same minimum required by the ADA for endodontic sealer cements).
radiographic imaging as one of several diagnostic tools.
A variety of clinical
criteria need to be taken into account before treatment decisions are made. For
example, probing-depths correlate very well with radiographic bone changes,
especially within the first few years following implant placement. Using more
than one test to determine what, if any, therapy is required is always a good
idea. Remember no test is perfect or absolute! And do remember: All
radiographic procedures require that the most appropriate and best practices be
used to minimize patient exposure to radiation.
- Wadhwani C, Schuler R, et al. Intraoral radiography and Dental Implant Restoration. Dentistry Today. Dent Today CE 2012.
- American Academy of Oral and Maxillofacial Radiology, Tyndall DA, Brooks SL. Selection criteria for dental implant site imaging: A position paper of the American Academy of Oral and Maxillofacial Radiology. Oral Surg Oral Med Oral Path Oral Rad Endodont 2000;5:630-637.