Surgically-placed dental implants are now the most popular choice for tooth replacement. But do you and your dentist know about 3D X-ray technology? Without it, you could suffer nerve injuries, permanent numbness, sinus perforations, involuntary drooling, incorrect tooth angles, even a broken jawbone. Called cone beam computed tomography or CBCT, it’s now the standard of care for many implant cases. For most, don’t get implants without it!
As general dentists, periodontists and prosthodontists move into a field that has been the exclusive territory of oral surgeons, this article helps you stay safe by making CBCT your ally. Based on actual outcomes and patient dental imagery, the article explores, educates and enlightens.
Dental Implants Introduction
Fig. 1 is a magnified representation of a tapered titanium dental implant. Typically, standard implants measure 4 – 6mm wide by 5 – 15mm long (a U.S. dime is 1.35mm thick). It’s not unusual for patients to receive several implants. Under proper conditions, fully edentulous patients (no teeth) can receive a mouthful of these long lasting cylindrical tooth root replacements. Patients want stable chewing solutions, and implants rise to the occasion. For others, an implant may immediately replace a tooth that has to be pulled. In some cases, an implant is an alternative treatment for a root canal.
Although mini dental implants are similar, they are not often used to replace teeth and are therefore not the subject of this article. Mini dental implants are very narrow — 2mm or smaller. A growing debate among dentists characterizes opinions on the use of mini implants as a solution for tooth replacement and denture support. The most experienced implantologists use them in limited situations, observing warnings like the one offered at the enriched website of Dr. S. Robert Davidoff, DMD.
Based on tooth root-shaped titanium cylinders that are machined with screw threads as shown in the photos above and to the right, standard implants are surgically placed in jawbone, below the gum after careful drilling and preparation. The titanium implant is literally screwed into the prepared hole (the osteotomy)
|Fig. 2: Implant supported crown|
where it bonds with jawbone over several months. The bonding is a unique property of titanium. Bonded or osseointegrated implants receive a metal abutment or post inserted in the top. It extends through and above the gum. The abutment either receives a temporary or permanent ceramic crown or firmly connects to a denture (the process called restoration). Restored implants often function better than healthy teeth (they don’t get cavities). With excellent patient care, properly installed implants can last decades.
The illustration at right conceptualizes a restored single implant. The gap below its tip illustrates procedural drilling depth of the osteotomy. The implant must be carefully torqued into the osteotomy to establish ideal conditions for osseointegration. The gap ultimately fills in with new bone.
My original impetus for purchasing a CBCT was to assist in the complete evaluation of a site to accept a dental implant. It allowed me not only to appreciate the true location of the inferior alveolar nerve canal and the mental foramen, but also the maxillary sinus and the true proximity to the incisive canal, adjacent teeth, and nasal floor. Plain films allow only the ability to judge the height of the alveolus, but with CBCT I was able to get complete information to a hundredth of a millimeter of not only the alveolar ridge height but also of its width. The CBCT also allows us to appreciate the morphology of that ridge. These are all extremely important factors to have in one’s command prior to implant placement.
“Comprehensive diagnosis and treatment planning is the cornerstone of all that we do in dentistry”, said Dr. Pikos. “While there can be more than one treatment plan for a given case, there is but one diagnosis, and cone beam CT has had a dramatic impact on this critical process, both in my private practice and with the Pikos Implant Institute.”
A companion directory to this article, CBCT X-ray Services Directory, provides an organic list of practitioners who behave like Doctors Tischler, Guttenberg and Pikos. The good news for patients is that the CBCT wave is coming on fast. There are now over a thousand CBCT installations around the world. If you live in a G20 nation, CBCT is probably nearby.
|Cone Beam Scanner|
Some forward-looking dentists and implantologists are installing CBCT units in their offices. Dr. Anthony Lizano, DDS, at Diablo Valley Implant Dentistry in Danville, California, recently installed an Imaging Sciences i-CAT cone beam scanner like the unit pictured (Fig. 3). At his practice’s website, Dr. Lizano says
“Our practice is one of a select few dental implant centers with an in-house 3D cone beam scanner. After this non-invasive, 20 second scan we can accurately examine the bone structure of your jaws. This allows us to precisely diagnose the bone quality and density for placing dental implants. In addition we get a clear view of the inside areas of the bone to see and avoid nerves (emphasis added) and determine sinus locations.”
These clinicians know that 3D is becoming the standard of care. Be suspicious of a dentist who claims this isn’t true (dental malpractice attorneys will affirm).
CBCT Provides Safety
Unless your case is simple, a CBCT is most important. It enables clinicians to see inside your jawbone with an accuracy as small as 0.1mm (less than the width of a human hair), and to avoid the problem illustrated at right. This image portrays three implants. #29 and #31 have been drilled and placed into the nerve canal in the mandible or lower jaw. This nerve serves each tooth and “enervates” the lip and chin through a branch called the mental nerve. Our ability to sense touch, heat, cold and pain is this nerve’s function. A patient’s complaint (after anesthesia wears off) might be “my (right or left side) lip and chin are painfully numb, and I can’t stop drooling because I can’t feel it to control it.”
Question your Clinicians
- What other solutions are available?
- What are the cost differences?
- What are the functional differences?
- What happens if nothing is done?
- Am I a candidate for teeth in an hour?
- How can I be sure that implants are needed? What’s the basis for your diagnosis?
- Who do you recommend to do the surgery, and why?
- How much experience have you had with the recommended implantologist?
- Do you know if the implantologist has a clean malpractice history?
- Can you recommend more than one surgeon and let me decide?
- Do I have enough jawbone to achieve a crown to root ratio of 1:1 or better? What are the tradeoffs if the ratio can’t be achieved? (A short implant life with risk of a cracked jaw is one tradeoff!)
- What kind of life cycle can I expect for the types of implants recommended for me?
- Are implant placement angles a problem in my case? How will you assure correct angulation?
- Does the standard of care for my case require a 3D cone beam X-ray?
- Will a CBCT 3D X-ray help guarantee the correct angulations and drilling depths?
- If the answer is no, would the diagnosis and surgery benefit from a CBCT or will I be wasting money?
- Can/will you refer me to a CBCT 3D imaging center? What are the choices and tradeoffs among different systems offered by these centers?
- Since my case is challenging, will you refer me to a regional expert at an accredited dental school, for an enriched opinion?
|Fig. 5A: 2D X-ray fails to reveal nerve impingement, says surgeon
|Fig. 5B Drill Strikes Nerve|
Get That CBCT and Second Opinion
If the initial opinion supported a CBCT, get it now. Your dentist will write the referral Rx and may direct that the X-ray be read by a Board-certified radiologist. However, if your dentist feels that CBCT is unnecessary, this becomes question #1 for that second opinion. Avoiding the outcome shown in Figure 4A and 4B is the purpose.
A 3D X-ray rotates around your head as you lay prone or sit up, depending on the manufacturer. A typical scan takes under 30 seconds and captures precision digital detail of your full jawbone and teeth (and surrounding head and neck), not just the region for implants. This data has occasionally revealed hidden health concerns (like tumors) and thus helped save patient lives. Clinicians who seek training in the analysis of 3D X-rays are also being taught how to recognize problems that would otherwise go undetected until symptoms appeared.
Reach out but Beware
Google searches are an excellent way for patients to acquire health information. Perhaps you found this article by searching dental implants. However, information that is both bias free and deeply biased results from Internet search. Don’t rely on any single information source, including this article. Consider each website’s motives.
One of the top-ranked websites for dental implants is http://www.yourdentistryguide.com/dental-technologies/. Calling itself the Consumer Guide to Dentistry, it provides a sponsored Dentist Directory (the motive). Although the site delivers extensive information, oddly it provides no easy access to guidance and information on CBCT X-rays and surgical guides. Only by deep diving will you find this:
CAT Scans: A 3-D image CAT scan is used to help implantologists (dentists who provide surgical and restorative implant services) view and work on the jawbone or surrounding bone structure to produce more accurate results. CAT scan technology has become increasingly specialized for dentistry as implants, rather than dentures, have become the standard of care for tooth replacement.
This is typical for the fruits of Google-like searches on dental implants, even as CBCT and surgical guides gain broad acceptance around the globe as the standard of care for a significant fraction of implant cases. For example, a website entitled dental-implants-guide.com claims to have the “best online info” but offers no content on CBCT, even through the site’s search function. It’s as if the dental community does not want patients to know up-front about the technology. However, if you read the conversations at dentist-to-dentist websites, it’s clear that CBCT X-rays are gaining broad support (a declining number of dentists are labelling them suitable only in difficult cases). Acceptance of CBCT is also evident at the leading implant manufacturer’s site, www.Nobelbiocare.com. Here, the topic receives direct menu selection under the name NobelGuide. And, a growing number of dentists are adding newly-available lower-cost CBCT units to their practice. As they become known, these are being listed in the companion CBCT Directory.
A list of other useful implant and CBCT websites is included
at the end of the article
Computer Aided Diagnosis and Manufacturing
CBCT X-rays have another key advantage: because they are digital, clinicians can use the data to create new accurate views in real time for treatment investigation, planning and the design of surgical guides.
Fig. 8: Materialise’ Simplant software adds the element of safety based on the patient’s
3D data. Fig. 9 shows more detail of a nerve collision
In Fig. 9A, a blowup from the Simplant image set, the clinician is attempting to find an implant that will correctly fit at a specific depth and angle in the jawbone. The patient’s CBCT data allows a thin “slice” of the jawbone to be selected for the Simplant try-in, and the software reformats the proper precision image. This is shown by the light to medium gray peanut shape. It’s a cross section of the mandible (lower jaw) at the position of the first molar (squeeze your lower right jawbone between left thumb and forefinger to help visualize this image).
|Fig. 9B: Artist’s Concept of Fig. 9A|
Avoiding injury is the chief safety benefit of CBCT. And here’s another: assuming that the try-in succeeded, the same digital data may be used to fabricate a precision surgical drilling and angulation guide after implant size, shape, angle and drilling depth are established with the software. Through the try-in procedure, the clinician arrives at a suitable solution that includes implant selection from among many manufacturers. The treatment plan data is then sent to Simplant and a SurgiGuide is quickly produced. As its name suggests, the guide prevents drilling errors.
In addition to Simplant, other makers of implants and treatment planning software are offering this service (e.g., NobelGuide). For good reason, it’s becoming a standardized treatment approach.
Experienced implantologists will be first to tell you that surgical guides are not always the answer. In actual clinical practice, with the patient under sedation and the jawbone fully exposed, the surgeon or dentist may encounter bone that is too soft at a predetermined location. It then becomes necessary to alter the location of the osteotomy — or abandon placement. With the patient’s CBCT on the chairside monitor during the procedure, the implantologist in this situation is armed with the best technology to succeed.
Other Important Considerations
CBCT X-rays usually require a prescription or referral. Whether your dentist recommends implants or you decide to ask for them, have the discussion right up front and get the referral if appropriate in your case. Ask about the need for a Board certified radiologist’s report, which is highly recommended if the amount of available jawbone is questionable or if drilling near anatomical structures like nerves and the mental foramen is contemplated.
Some implantologists resist the use of CBCT. This is regrettable and potentially hazardous. One implantologist testifying in a malpractice case stated he only uses single-tooth periapical X-rays even when several successive implants are being placed. This is like a carpenter choosing a hand saw when a power table saw is available nearby. If your dentist and/or implantologist fails to raise the CBCT topic, bring it up yourself, letting the clinician know that safety, not expense, tops your list.
More information on this topic is available in a
Google Knol by Dr. Terry Shapiro
- Who delivers the critical follow up treatment, which can last for several months via regular office visits? The serious inflammatory condition called peri-implantitis can threaten your implants, necessitating aggressive treatment.
- If something goes terribly wrong after you’ve returned home (for example, an implant falls out or numbness develops and persists), from whom do you seek corrective treatment?
- If genuine malpractice occurred during your offshore treatment, how can you sue to win a fair recovery? It’s difficult at best at home.
When the budget is limited, a better approach is to seek treatment at an accredited school of dentistry. In the U.S., a list is maintained at http://www.dentalsite.com/dentists/densch.html. Most dental schools offer implants and some of the best clinicians are the supervising instructors. Costs are sometimes less than half the commercial rate. These schools also offer CBCT as well as accompanying Board-certified radiology reports to help diagnose and guide the surgery. Patients in Northern California, for example, have a choice of UCSF and University of the Pacific, and both schools offer CBCT X-rays and Board-certified radiologists.
Another choice during our current economic downturn is to do the unthinkable: negotiate with your dentist. A scan of professional dental websites reveals that dentists are hurting, too. Don’t be afraid to attempt to strike a deal that is win-win for both patient and dentist.
Implantologists Who Support CBCT
CBCT technology continues to gain traction around the globe at the same time that an increasing number of general dentists are starting to place implants, often with minimal training. Before long, simple implants will be standard in most cosmetic dentistry practices while difficult cases continue to be the specialty of oral surgeons, periodontists and prosthodontists.
As dentistry and medical schools train more professionals, the word is spreading about CBCT, helping standardize its use. If you are an implantologist who wants patients to know that you employ CBCT for the patient’s benefit, please accept my invitation to list yourself in this section of the article, in a future revision. Simply use the comment tool below or click to send an e-mail. Include your contact information and location(s).
Sadly, some fraction of those poor outcomes will be victims of negligence or malpractice. For example, the patient involved in the nerve penetration portrayed in many of this article’s examples discovered that the implantologist rushed through the surgery, including all of the following steps, in a mere 30 minutes:
- Surgical flapping of the gingiva (gum) and retraction to fully expose mandibular jawbone
- Under a written protocol of care and caution to prevent overheating of bone and warnings that the drills are longer than the implants being placed, drilling and placement of the first implant (up to six drilling steps)
- Drilling and placement of the second implant (up to six drilling steps)
- Drilling and placement of the third implant (up to six drilling steps)
- Placement of three healing caps
- Surgical suturing of the gingiva over the implants to foreclose the possibility of germ entry (often calls for placement of a special membrane)
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Further Viewing, Further Reading
Informative Web Links
- NY Times article (22 November 2010), video on CBCT radiation (preceded by a commercial but worth watching)
- 3D Orthodontist.com advances the use of CBCT for precision orthodontics
- Wikipedia http://en.wikipedia.org/wiki/Dental_implants (note: the content has recently been edited to reduce CBCT applicability and importance, which is opposite of the trend. This may be vandalism to protect an at-risk implantologist)
- OsseoNews http://osseonews.com/
- American Dental Association http://ada.org/
- 3D Cone Beam X-rays http://www.conebeam.com/?q=cbct-clinician/verDental
- Implant Patient Animated Movie http://www.bicon.com/patient/video.html
- Nobel Biocare website http://www.nobelsmile.us/en_us/
- Planmeca Office 3D website http://www.planmeca.com/index.php?page=00301&lng=1
- Materialise Simplant website http://materialise.com/materialise/view/en/84113-Dental+homepage.html
YouTube Videos on Dental Implants
Useful 3D cone beam X-ray websites
- PowerPoint presentation of available CBCT Scanners, with a link to each: http://www.box.net/shared/xb0tuzskc2
- American Society of Radiologic Technologists https://www.asrt.org/content/News/IndustryNewsBriefs/CT/CTDentalSy050222.aspx
- Straumann video on measurement and analysis procedure for treatment planning http://www.straumann.us/us_index/pc_us_products/pc_us_archive.htm/pc_us_archive?func=movie&type=9864
- Imaging Sciences iCAT http://www.imagingsciences.com/pro_iCAT_design.htm
- NewTom 3G http://www.afpimaging.com/newtom
- Accu-i-Tomo http://www.jmorita-mfg.com/en/en_products_diagnostics_general_3d_accuitomo.htm
- Comprehensive 2001 implant article: http://radiology.rsnajnls.org/cgi/content/full/219/2/334
- Nobel Biocare NobelGuide http://www.nobelbiocare.com/global/en/ClinicalProcedures/NobelGuide/default.htm?flash=falseC-Dental X-ray Laboratory http://www.cdental.com/index.php?action=tech