Posts for: January, 2020
The CAT scan is a relatively recent technique in dentistry, used to get an image of what’s happening deep within your jaws. You may be wondering what a CAT scan tells us that a conventional x-ray picture does not, and whether it is worth the extra expense to get one. And how does a CAT scan compare with a conventional x-ray in terms of radiation exposure?
CAT stands for “computer assisted tomography.” Often it’s just called a CT scan, for “computerized tomography.” The word “tomography” comes from roots meaning “slice” and “write.” Tomographic techniques take repeated two dimensional pictures, similar to repeatedly slicing through an object, and then assembles them with a computer to produce a three dimensional (3-D) image.
The latest type of CT scan used in dentistry is called CBCT, or Cone Beam Computed Tomography. The Cone Beam refers to a spiral beam of x-rays, which is used to create a series of two dimensional images from which a computer creates a 3-D image. Such an image is of great value in assessing problems and planning treatment.
Here are just a few examples of how a CBCT scan can be used. Orthodontists can see skeletal structures and developing teeth that are still inside the jawbone while planning strategies for directing the teeth in order to arrive at a better bite. Oral surgeons can find impacted or missing teeth, see their locations, and view their proximity to nerves and sinuses, assisting them in planning surgeries. These scans are particularly useful for root canal specialists because they show root canals that are less than a millimeter wide and even reveal accessory canals that may not be visible on conventional x-rays. In cases of sleep disorders such as sleep apnea, a CBCT during sleep can be used to view a person’s airway and how it may be blocked by the tongue and other soft tissues in a person’s throat during sleep.
Compared to background radiation, the amount of radiation delivered in dental x-rays is minimal. A CBCT delivers a dose of radiation that is less than a typical full mouth x-ray series but more than a typical two dimensional panoramic radiograph. Generally CBCT scanners deliver lower doses than medical CT scanners.
With one low-dose CBCT scan, we can get an accurate idea of the internal structure of your bones and teeth and how they are situated in relation to each other. Prior to the availability of such images, many of these relationships had to be discovered in the course of a surgery or other treatment. Thus such a scan can aid greatly in the quality of treatment you will receive.
Not long ago, the most affordable option for total tooth loss was a removable denture. Dentures, prosthetic (false) teeth set in gum-colored acrylic plastic bases, can effectively restore function and appearance. But the appliance continues to have one major drawback: it can accelerate bone loss in the jaw.
Like other living tissues, older bone cells die and become absorbed into the body (resorption). Normally they're replaced by newer cells. The forces generated when we chew our food travel through the teeth to stimulate this new growth. This stimulus ends when we lose our teeth, and so cell replacement can slow to an abnormal rate. Eventually, this causes bone loss.
Removable dentures can't provide this stimulation. In fact, the pressure generated as they compress the gums' bony ridges can even accelerate bone loss. That's why over time a denture's fit can become loose and uncomfortable — the bone has shrunk and no longer matches the contours of the dentures.
In recent years, though, a new development has been able to provide greater support to dentures while at the same time slowing or even stopping bone loss. We can now support dentures with dental implants.
Implants are best known as individual tooth replacements: a titanium metal post replaces the root, while a life-like porcelain crown attaches to the post to replace the visible tooth. In addition to providing a longer-lasting alternative to removable dentures, implants provide a very important health benefit: they improve bone density because they mimic the function of natural teeth. Bone cells are naturally attracted to the titanium; they adhere to the titanium post and are stimulated to grow through the action of chewing, increasing bone density and securing the implant's hold in the jaw.
Using the same technology we can support removable dentures, or even full fixed bridges. Rather than rest directly on the bony ridges, a denture can make a secure connection through a coupling system with just a few strategically placed implants. We can also permanently attach a full bridge by fastening it to a few implants with screws.
Not only do we eliminate the pressure from dentures compressing the gums and bone tissue, we can actually stimulate bone growth with the implants. Although more costly upfront than traditional dentures, unlike traditional dentures which must be replaced every five to seven years, long-lasting implants may be more cost-effective over the long-run.
If you would like more information on implant-supported tooth replacement, please contact us or schedule an appointment for a consultation. You can also learn more about this topic by reading the Dear Doctor magazine article “New Teeth in One Day.”
Radiographic (x-ray) images are an indispensible diagnostic tool in dentistry. One of the most routine and useful types of x-rays dentists take is the so-called bitewing. Here are some things you may want to know about this common diagnostic procedure.
What are bitewing x-rays?
Bitewings reveal the presence and extent of decay in the back teeth, specifically in areas where adjacent teeth touch each other. Unlike other areas of the teeth, these contacting surfaces between adjacent teeth can’t be examined visually. Bitewings can also show areas of bone loss around teeth — a sign of periodontal disease; however, they are not taken for that purpose because bitewings will not show the complete root surface that is surrounded by bone.
Why are they called that?
The name “bitewing” refers to how the film — or sensor, in the case of a digital x-ray — is positioned in the mouth: The patient bites down on a little tab or wing that holds the apparatus in place.
How often do I need them?
This is determined on a case-by-case basis, with the goal of not exposing you to any more radiation than necessary — even the minimal amount found in a series of bitewing x-rays. Your individual susceptibility to caries (tooth decay) and personal dental history will play a major role in determining how frequently you need radiographic examination — and, for that matter, how often you need to come in for routine cleanings and exams.
Are they safe?
The safety of bitewing x-rays is best illustrated with a comparison to the regular daily radiation exposure we get every day from environmental sources, which is about 0.01 millisieverts — the unit of measure we use for radiation. A series of 4 bitewing x-rays exposes you to 0.004 millisieverts of radiation — less than half of the daily exposure. Undetected tooth decay, which can spread quickly through the softer inner layers of teeth, is considered much more dangerous!
If a bitewing x-ray shows that there is tooth decay, what happens next?
If the cavity is very small, we may be able to treat it during the same appointment. If not, we will make a separate appointment to make sure it is taken care of promptly. The sooner tooth decay is treated, the better!