The short answer
Professional guidelines recommend cross-sectional imaging, usually a cone beam CT (CBCT) scan, when planning implants, because it shows bone width and the position of nerves and sinuses in 3D. Many offices refer you to a dental imaging centre for it. The scan takes well under a minute; the images are then sent to your dentist, who goes over them with you at a later visit.
Why a flat picture isn't enough
A regular dental X-ray squashes three dimensions into two. It's good for spotting decay or checking bone levels between teeth. What it can't show well is how wide the bone is, or exactly how close a nerve or sinus sits to where an implant would go.
Those are exactly the things an implant plan depends on. That's why professional guidelines, including a position statement from the American Academy of Oral and Maxillofacial Radiology, recommend cross-sectional imaging for implant sites, most often a cone beam CT scan.
2D dental X-ray
- Flat image, structures overlap
- Shows bone height, not width
- Panoramic images magnify unevenly, so measurements are approximate
- Very useful for screening and check-ups
3D CBCT scan
- Viewable from any angle, in slices
- Shows bone height and width at the site
- Measurements closely match true dimensions
- Used when the extra detail is worth the extra dose
What CBCT actually is
Cone beam computed tomography is a type of 3D X-ray designed for the head and jaws. A cone-shaped beam rotates once around your head while you stand or sit still. The scanner collects many images and a computer assembles them into a 3D view your dentist can move through slice by slice.
- The scan itself usually takes well under a minute
- The radiation dose is generally lower than a conventional medical CT of the same area, though it varies a lot between machines and settings
- The files can be shared with your dentist and loaded into implant planning software
How a referral to an imaging centre works
Many dental offices don't have their own CBCT scanner. Instead, they refer patients to a dental imaging centre. It's a common, normal way of doing things, and the scan is read and used for planning the same way.
- Your dentist writes a referralIt says which area to scan and what question the scan needs to answer.
- You book and goRemove glasses, earrings and any removable dental work. Hold still for the scan. There's no recovery time.
- The images go to your dentistThe centre sends the files afterwards, sometimes with a radiologist's report. You usually don't get results on the day.
- You go over them togetherAt a later visit, your dentist shows you what the scan found and what it means for the plan.
Can you show me my scan and walk me through what it shows?
If you're in Ontario, imaging and referrals in Ontario covers who sends you, who usually pays for the scan and how your records move between offices.
What the scan helps your dentist see
- Bone height and width: whether there's room for an implant of a suitable size, or whether grafting is needed
- A general impression of bone quality: CBCT can suggest whether bone looks dense or more porous, but its grey values aren't a reliable density measurement, so your dentist also judges bone quality during surgery
- The angle: how an implant could be positioned to stay clear of nerves and line up with the tooth it will carry
- Hidden problems: cysts, infection or leftover root fragments that need dealing with first
- Neighbouring roots: so the implant keeps a safe distance from the teeth beside it
The structures everyone wants to avoid
A big part of planning is knowing where the things you don't want to touch are.
Runs through the lower jaw and gives feeling to the lip and chin. Injury can cause numbness that is sometimes permanent.
Where that nerve exits the bone. Its position varies from person to person.
Sits above the upper back teeth. Too little bone below it may mean a sinus lift first.
Can limit bone height for upper front implants.
From scan to surgery
The same scan often keeps working after the first planning visit.
- Virtual planning: your dentist can try different implant sizes and angles on the 3D model before surgery
- Surgical guides: the plan can be turned into a custom guide that helps position the implant. A systematic review of guided implant surgery found placement generally close to the digital plan, though small deviations still occur, so safe margins are still built in
- Grafting plans: if bone is short, the scan shows how much and where
After surgery, healing is usually checked with ordinary two-dimensional X-rays over time.
Is the radiation worth it?
It's a fair question, and a good dentist will be happy to answer it. The guiding principle is to use radiation only when the information is worth it, and to scan the smallest area that answers the question. For implant planning, the guidelines generally come down on the side of 3D imaging, because placing an implant without knowing where the nerve or sinus sits carries its own risks.
If you've had recent scans elsewhere, or you're pregnant or might be, tell both your dentist and the imaging centre.
Why do I need this scan, and how large an area will it cover?
Common questions
Is a CBCT scan safe?
When it's used for a good reason, yes. Dental CBCT generally uses a lower dose than a conventional medical CT, although the dose varies widely between machines and depends on how large an area is scanned. Guidelines say a scan should be recommended only when the diagnostic benefit justifies the exposure.
How long does a CBCT scan take?
The scan itself usually takes well under a minute, and the whole appointment typically only a few minutes. The images are then sent to your dentist, who reviews them and goes over the findings with you, usually at a separate visit.
Will my insurance cover CBCT imaging?
It depends on your plan. Some plans cover CBCT when it's needed for implant planning; others don't. Check with your insurer, and ask whether they need a pre-determination first.
Can I get a copy of my scan?
Generally, yes. You can ask for copies of your records, including imaging, for example if you want a second opinion. Ask the office or imaging centre how they share the files.
References
- Tyndall DA, Price JB, Tetradis S, Ganz SD, Hildebolt C, Scarfe WC. Position statement of the American Academy of Oral and Maxillofacial Radiology on selection criteria for the use of radiology in dental implantology with emphasis on cone beam computed tomography. Oral Surg Oral Med Oral Pathol Oral Radiol. 2012;113(6):817-826.
- Bornstein MM, Scarfe WC, Vaughn VM, Jacobs R. Cone beam computed tomography in implant dentistry: a systematic review focusing on guidelines, indications, and radiation dose risks. Int J Oral Maxillofac Implants. 2014;29(Suppl):55-77.
- Ludlow JB, Ivanovic M. Comparative dosimetry of dental CBCT devices and 64-slice CT for oral and maxillofacial radiology. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2008;106(1):106-114.
- European Commission. Radiation Protection No. 172: Cone beam CT for dental and maxillofacial radiology — evidence-based guidelines (SEDENTEXCT project). Luxembourg: European Commission; 2012.
- Tahmaseb A, Wu V, Wismeijer D, Coucke W, Evans C. The accuracy of static computer-aided implant surgery: a systematic review and meta-analysis. Clin Oral Implants Res. 2018;29(Suppl 16):416-435.
