Detecting carotid artery calcification
Narrowing of the carotid artery can lead to the formation of an embolus and decreased blood supply to the brain or eyes and subsequent strokes of varying severity.
If the space in the carotid artery is narrowed by 50 percent or more, the stenosis is considered significant, and carotid endarterectomy (CEA) to reduce the patient’s stroke risk may be necessary.
Although plaque in the carotid arteries can be either calcified or noncalcified, calcifications in carotid plaque are detectable on standard dental panoramic radiographs. Because panoramic radiographs are routinely taken in the dental setting, an accidental finding of a suspected carotid calcification may indicate narrowing of the carotid artery and warrant a patient referral for further examination by carotid ultrasound.
Identifying patients with significant carotid stenosis by means of carotid calcifications on panoramic radiographs can be tricky. Other structures in the same region can be calcified, or observable calcified plaque may not have created significant narrowing.
Among the questions for dentists analyzing these images: How often are significant stenoses calcified? How often are calcified stenoses detected in panoramic radiographs?
Scientists at Umea University in Umea, Sweden, conducted a study to find out and published their findings in the May 2014 issue of Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology.
The study group consisted of 100 patients from northern Sweden with suspected significant carotid stenosis and potential eligibility for CEA or carotid angioplasty. All such patients in northern Sweden are referred to the center, where they are reexamined by carotid ultrasound. The sample size was reached by virtue of study eligibility design from an original total of 251 consecutive patients treated at the center from August 2007 to December 2008.
The scientists aimed to analyze carotid plaque removed from patients with significant carotid stenoses for evidence of calcification. They wanted to determine how often panoramic radiographs reveal calcifications on the side of the neck where removed calcified plaque was found. They were interested in the frequency in which carotid calcifications are found on panoramic radiographs of patients with significant carotid stenoses, including calcifications found in the artery on the opposing side. They also sought to assess the utility of frontal radiographs in identifying patients with carotid stenosis.
All 100 patients were preoperatively examined with panoramic and frontal radiographs taken according to routine dental protocol. Two specialists interpreted the radiographs blinded to each other’s observations and the side on which the carotid stenosis was situated.
All 100 patients underwent CEA. Scientists then analyzed carotid plaque removed during CEA. Calcified carotid stenosis was correlated with carotid calcifications found on panoramic radiographs. Calcified carotid stenosis that was not seen on panoramic radiographs was reanalyzed by additional methods.
Scientists said the main finding was that significant carotid stenosis was nearly always calcified (99 percent). Of the radiographic examinations associated with removed plaque, 100 of 101 had calcifications. Furthermore, most of the patients (84 percent) with a significant carotid stenosis were identified by panoramic radiographs.
Authors also noted that some patients showed calcification only on the opposing side of the significant stenosis (9.5 percent).
“Because any finding of calcification in the carotid arteries could be an indication for further examination, the significant stenosis in these patients would have been diagnosed in a subsequent ultrasound examination,” the authors said.
Panoramic examinations without visible carotid calcification occurred in 25 neck sides with confirmed calcified carotid stenosis. Further analysis showed that a large number of these calcifications were situated below the inferior borders of the panoramic images. “It is reasonable to assume that the main reason for failing to detect the calcified carotid stenosis by panoramic radiographs was that the calcification was positioned below the depicted area,” authors said in discussion.
They concluded that carotid stenosis are almost always calcified and can often be detected on panoramic radiographs. Frontal radiographs did not contribute significantly to detection, and undetected calcified carotid stenosis was mostly below the depicted area of the panoramic radiographs.
“A large proportion of patients at risk for stroke owing to significant carotid stenosis can be detected by panoramic radiographs, independently of whether the detected calcification coincides with the stenosis and also independently of age and gender,” the authors said.
Consulting Editor: Laurie C. Carter, DDS, PhD
Past president, American Academy of
Oral and Maxillofacial Radiology
Pursuing improved treatment for BRONJ
New research may lead to better treatment for bisphosphonate related osteonecrosis of the jaw (BRONJ), a serious side effect of the medication that can trigger severe bone loss.
Bisphosphonates are prescribed to patients worldwide for diseases such as osteoporosis and malignancies that have spread to the bones. Based on the rationale that bisphosphonates can cause systemic changes in bone that may begin spontaneously, much of the dental literature recommends a conservative treatment approach for their use.
Finding no bisphosphonate related osteonecrosis of bones—other than the jawbone—reported in the literature, scientists at Leiden University in The Netherlands surmised that the presence of teeth in the jaw may be a factor in BRONJ. If a dental cause could be established, then treatment results could possibly be improved by using the same treatment that’s used for chronic osteomyelitis (CSO), which almost always has a dental origin.
To gain more insight into the mechanisms of the etiology of BRONJ, the scientists conducted a retrospective study to determine the cause in 45 patients who had been diagnosed with BRONJ. The study population had been treated and followed-up at the University’s medical center, and each subject had been taking a bisphosphonate for at least 12 months intravenously or 24 months orally.
To expose the distinction between spontaneous and dental causes of BRONJ, patients were categorized into four groups according to their luxating moment of BRONJ: those with a certain dental focus, a presumable dental focus, spontaneous and unknown.
Those who experienced BRONJ with a recent dental procedure, such as an extraction, removal of retained roots, implant placement, apical inflammation or clear preexistent periodontal problems in the region of BRONJ were placed in the certain dental focus category.
Patients were placed in the presumable dental focus category if the region of the molar teeth of the lower jaw and the hyoid bone at the base of the tongue was elevated (elevated mylohyoid ridge), with a clear knife-edge ridge and gingival trauma caused by non-fitting dentures.
The spontaneous group was reserved for patients who had exposed bone with no previous dental history, therapy, trauma or complaints related to dentures. Those with unknown, unclear or untraceable history would be categorized as unknown.
The study population mainly suffered from malignancies (57.8 percent or 26 patients) or osteoporosis (40 percent or 18 patients). One patient had Paget’s disease. Of the 45 patients, 35 had BRONJ of the mandible, seven of the maxilla and three had BRONJ of both jaws.
Scientists did not find a convincing spontaneous origin for BRONJ in any of the patients. One patient was classified in the unknown category and 44 of the 45 patients were grouped in the certain or presumable dental focus categories.
“In the category ‘certain dental origin’ patients had procedures, which created a direct port d’ entrée for microorganisms to enter the jaw,” the authors said. “This is in line with the pathogenesis of osteomyelitis of the jaw with a common dentoalveolar start of the disease and subsequent spreading throughout the jaw.”
Study authors also reported on previous research strongly suggesting a pathogenesis of BRONJ similar to what they called the “ordinary” osteomylelitis.
“When the pathogenesis of BRONJ resembles the pathogenesis of chronic osteomyelitis, early treatment according to the principles of the treatment of osteomyelitis should give better results than those reported in the literature of BRONJ so far,” the authors noted.
Their findings were published in the September 2013 issue of Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology.
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Analyzing the temporal bone with CBCT
Dentists and oral radiologists must be able to identify normal anatomical variations and pneumatization (air cell) patterns of the temporal bone if they are to recognize pathologic changes that may require referring a patient to a specialist.
Additionally, because these air cells can become sources of cerebrospinal fluid leakage after surgery, the pneumatization pattern of the temporal bone can affect any surgical procedure of the skull base.
Many studies have reported on the variety of pneumatization patterns and their classifications using conventional computed tomography (CT). Although CT has advantages over CBCT, especially for depicting soft tissues, comparable evaluation of the bony components of the skull base is possible at a lower radiation dose and at a lower cost with CBCT, scientists at the University of Connecticut reported. To analyze the topic, they used CBCT to classify different repeated patterns of temporal bone pneumatization and also to calculate their volume. The study was published in the March 2014 issue of Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology.
Researchers evaluated 155 temporal bones from 78 patients with no radiographic evidence of disease. Scientists examined patterns in the middle ear, the perilabyrinthine region (around the labyrinth of the ear), and the petrous apex (the hard portion of the temporal bone that forms a protective case for the inner ear). They calculated the volume of temporal bone air cells, including the middle ear cavity, with CBCT data.
Their study showed that CBCT can be effectively used to evaluate and classify the repeated pattern of the temporal bone air cells. The three studied regions, which are critical structures, can be located easily on CBCT scans and used as references to assess pneumatization patterns.
In discussion, authors reported on previous research findings that CBCT images of a well-pneumatized middle ear and temporal bone are comparable to high resolution multi-slice computed tomography (MSCT) for visualizing various pathologies.
“In a variety of temporal bone conditions, pneumatization can be affected significantly; this study shows that analysis of air cells and their volume measurements can be done effectively using a lower-dose alternative like CBCT,” the authors said.
CBCT and evidence-based benefits
A systematic review of the evidence on maxillofacial CBCT for dental implant therapy is featured in the January/February 2014 Supplement of the International Journal of Oral & Maxillofacial Implants.
Two-dimensional imaging and panoramic radiography have long sufficed to provide the information dentists needed to produce high success rates. The use of cross-sectional imaging—such as tomography, multi-detector computed tomography, or, most recently, maxillofacial cone beam computed tomography (CBCT)—should be based on clear clinical benefits, the study’s authors said.
They said cross-sectional imaging should take into account the evidence that supports additional benefits, as well as the recommendations of relevant representative organizations.
Seeking this knowledge, they conducted an in-depth hand search and gray literature search on the use of cross-sectional imaging, specifically CBCT. They sought available evidence that answered the following three focus questions about pre-and/or postoperative assessment of potential dental implant sites:
(1) Do guidelines currently exist for the use of cross-sectional radiography, particularly CBCT imaging?
(2) Are there specific indications or contraindications for the use of cross-sectional radiography, specifically CBCT imaging?
(3) What additional radiation dose risks are associated with the use of cross-sectional radiography, specifically CBCT imaging, compared to other radiographic modalities?
Authors performed their review using a PICO-based search strategy of publications indexed in the MEDLINE database from Oct. 31, 2012 and supplemented these results with a hand and gray literature search.
Although 12 publications were initially identified as providing guidelines, only three satisfied the requirements for the highest level of compliance with currently accepted guideline statement criteria. Clinical practice guidelines are defined in the literature as “statements that include recommendations intended to optimize patient care that is informed by a systematic review of evidence and an assessment of the benefits and harms of alternative care options.”
“Most published national and international guidelines on implant dentistry do not offer evidence-based action statements developed from a rigorous systematic review approach,” authors said about their finding. They asserted that the results show “a clear need for guidelines that provide strong action statements based on a rigorous methodological review of the evidence.”
Regarding specific indications or contraindications for CBCT use, authors described many contributions to the dental literature from organizations, including but not limited to the American Academy of Oral and Maxillofacial Radiology, European Academy of Osseointegration, The Working Group for Radiology of Germany and The Academy of Osseointegration. They took note that all reports identified were based on nonrandomized clinical trials, either cohort or case-controlled studies.
Authors reported extensively about indications in the literature for CBCT use, including preoperative analysis regarding specific anatomic considerations, site development using grafts, and computer-assisted treatment planning. Postoperative evaluation focused on complications due to damage of neurovascular structures.
They found that effective doses for different CBCT devices exhibited a wide range, with the lowest dose being almost 100 times less than the highest dose.
Authors called for specific equipment protocols that are task specific and patient specific. They concluded that significant dose reduction can be achieved by considering minimum image-quality parameters, exposure factors and restricting the field of view to the region of interest.
‘JADA Live’ to spotlight office design
The first “JADA Live” presentation for 2014 will focus on practice improvement through office design.
To help dentists make the most of their practice investment, the publishers of The Journal of the American Dental Association will bring “JADA Live—Advancing Your Practice Through Office Design” to the Fairmont Scottsdale Princess, Scottsdale, Ariz., Friday, June 13, from 9 a.m. to 5:30 p.m.
Dr. Mark Tholen, former CEO of T.H.E. Design, will break down the office design process and teach techniques aimed at boosting office efficiency. The seminar will include interaction with exhibitors and hands-on sessions with the latest in dental technology.
“JADA Live” participants will earn six units of continuing education credit with successful completion of the course. To register, visit http://jadalive.org or call 1-888-692-2631. Registration for the seminar is $315 for ADA members, $375 for nonmembers.
The first 100 dentists to register will receive, free of charge, the ADA’s bestselling new book, “The ADA Practical Guide to Dental Office Design,” which retails for $134.95.
ADA discounts dental X-ray brochures
Dentists can save 15 percent on all ADA Catalog products through June 30, using promo code 14357E.
Included in this offer are two dental X-ray brochures:
Digital X-Rays (W522). The clinical benefits of digital radiography may not be evident to patients, but this brochure points out that digital images are faster to create and send. They also are easily enlarged and enhanced. The brochure tells patients how digital X-rays work and addresses questions about radiation safety. The six-panel brochure is available in packs of 50 to members for $26; retail price is $39.
Dental X-Ray Exams (W566). This brochure explains to patients how an X-ray works, why X-rays are beneficial and how often they are recommended. It also provides explanations and images of the different types of dental X-rays and will help the dental team reassure patients of the minimal risk associated with dental X-ray. That includes patients who are pregnant or who have received radiation treatment for cancer. The eight-panel brochure is available in packs of 50 to members for $27; retail price is $40.50.
Both brochures are available in quantities of 100, 500 and 1000 for a discounted unit price. Visit adacatalog.org to view the dental X-ray brochures, as well as a variety of other patient-education brochures.
To place an order, visit adacatalog.org or call the ADA Members Service Center at 800/947-4746. Remember to use promo code 14357E to save 15 percent on all ADA Catalog products.
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What is Specialty Scan?
This is one in a series of quarterly newsletters updating dentists on selected specialties in dentistry. Information presented is aggregated and summarized from previously published materials, each item attributed to its publication of origin. This issue of JADA Specialty Scan focuses on oral and maxillofacial radiology, the second in the series on this topic for 2014. Other Specialty Scan issues are devoted to prosthodontics, orthodontics, periodontics, endodontics and oral and maxillofacial radiology. The ADA has engaged the specialty organizations in these areas as well as its own divisions of Science and Legal to assist with these newsletters. We welcome your feedback on this and all Specialty Scan issues.
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