Using CBCT to diagnose vertical root fractures
The use of radiographs for detection of vertical root fractures (VRF) is somewhat controversial. Because periapical X-rays don’t usually capture the root fracture itself, they often are used to diagnose indirectly the presence of VRFs.
Cone beam computed tomography (CBCT) is small-volume tomography. A cone-shaped X-ray in a single exposure captures a cylindrical or conical volume of bone and teeth.
Scientists interested in comparing the sensitivity, specificity and accuracy of CBCT with conventional periapical radiography for the detection of vertical root fractures pursued a systematic review of the literature investigating both endodontically treated and untreated teeth.
They published their findings in the November 2014 issue of Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology.
Authors searched databases of MEDLINE/PubMed, EMBASE and the Cochrane Library from 1970 through April 2014, and supplemented the results with a hand literature search.
They examined diagnostic results for teeth divided into four groups: in vivo; ex vivo/untreated teeth; ex vivo/treated teeth; and ex vivo with post; from 12 studies ultimately designated for analysis: three in vivo and nine in vitro. For each group, cases were divided on the basis of the voxel size of the CBCT device that was used. Number of teeth, specificity, sensitivity and accuracy were recorded.
The results left authors unable to clarify whether CBCT can be superior to periapical radiographs in the detection of VRFs. No significant differences were found between radiographic techniques.
However, researchers found that adequate choice of voxel size appeared to be the most important parameter when diagnosing VRFs.
“Interestingly, the results, taken together, indicated that compared with periapical radiographs, CBCT had similar specificity (the ability to detect all true negatives) but higher sensitivity (the ability to detect true positives),” authors said. In vivo studies showed that CBCT had a significantly higher sensitivity than periapical radiography, particularly when voxel size smaller than 0.2 millimeter was used.
Authors postulated, “Taking into consideration the outcomes of the present review, it can be stated that CBCT may be useful in the diagnosis of VRFs.”
They also reasoned, “In many cases, bony dehiscences or lesions, which can be associated with the presence of a VRF, can be invisible in a periapical radiograph because they may be covered by the tooth structure itself or by bony structures. Three-dimensional visualization is useful in the detection of such lesions and is a valuable tool for diagnosing the presence of a VRF even in the absence of direct visualization of the VRF.”
Authors noted that another advantage of CBCT may be related to treatment and prognosis. They referred to a recent study that noted, “In case of a ‘hopeless’ tooth, 3-dimensional imaging of the bony defects and of the bone volume can help in the planning of immediate post extraction implant positioning.”
Among conclusions, researchers reiterated that the review did not find that CBCT may present additional information for the diagnosis of the presence of a VRF.
“However, because absence of evidence is not evidence of absence, more in vivo studies designed comparing periapical radiography and CBCT may help develop a better understanding of the potential benefit of modern radiographic investigation devices for VRF diagnosis,” they said.
Consulting Editor: Laurie C. Carter, DDS, PhD
American Academy of
Oral and Maxillofacial Radiology
Radiation protection and children
An editorial published in the September 2014 issue of Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology encouraged a heightened awareness of ways to improve radiation protection for children receiving dental care.
The authors underscored their support for the Image Gently in Dentistry campaign, which includes a six-step plan for standardizing clinical workflow and encouraging team responsibility.
“Implementation of the recommendations in this plan can be an effective tool in the ongoing effort to maximize radiation safety during maxillofacial radiographic procedures on pediatric patients,” they wrote.
Safety concerns about maxillofacial radiology for children rose as exposure to ionizing radiation from medical imaging also increased. Research showed that by 2006 medical exposure had surged to constitute nearly half of the total radiation exposure of the U.S. population from all sources.
“Computed tomography (CT) is known to be the major single contributor of diagnostic radiation exposure,” researchers reported.
Other concerns: children’s longer life expectancy and increased radiosensitivity of some developing organs and tissues, make them more susceptible to the effects of radiation exposure for most cancers.
The researchers noted that although individual doses from radiographic procedures in dentistry are relatively low, examinations are common. An estimated 500 million intraoral bitewing and full-mouth radiographic procedures were performed in the United States in 2006 — almost twice the number of conventional medical radiographic and fluoroscopic examinations combined.
Authors considered that a general rise of dose in dentistry may be attributed to the escalating use of cone beam computed tomography (CBCT) systems, expected to surpass the number of standard CT systems in the near future. Although the reported range of effective doses is lower than for examinations performed using standard CT systems, CBCT doses reportedly fall within a wide range. Furthermore, there is some unease about overuse of the technology, as there are those who propose CBCT use for routine imaging.
The report includes the Image Gently campaign’s six-step plan to minimize radiation exposure to children in the dental office, as outlined by The Alliance for Radiation Safety in Pediatric Imaging. The authors note that the Alliance has recruited more than 80 organizations, medical societies, agencies and regulatory groups as members joining forces to improve patient care and change practice through education and awareness.
The messaging underscores the principle that one size does not fit all, “especially when it comes to using radiography during pediatric dental procedures.” The steps described are based on the concepts of justification for use and reduction of radiographic exposures as low as diagnostically acceptable (ALADA). This a variation on the acronym ALARA (as low as reasonably achievable), a principle advanced by the American Dental Association.
The steps include:
- Select X-rays for a patient’s individual needs, not as a routine. Use the fastest image receptor possible.
- Collimate the X-ray beam to expose only the area of interest.
- Use thyroid collars.
- Child-size the exposure.
- Use CBCT only when necessary.
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Renal failure and the dental connection
Think a nephrologist is bound to be the first to diagnose chronic renal failure? Think again. A team of scientists studying oral manifestations of renal osteodystrophy (ROD), said jaw involvement is common and radiographic alterations often are one of the earliest signs of chronic renal failure.
The scientists published a case report on chronic renal failure with ROD oral manifestations in an 11-year-old male in the August 2014 issue of the Journal of Clinical and Diagnostic Research.
As the incidence of chronic renal disease increases due to factors including diabetes and hypertension, so too does the number of patients dentists treat with ROD — a common complication of chronic renal disease.
ROD occurs early in the course of chronic renal failure and progresses as kidney function wanes. The bone alteration is believed to arise from increased parathyroid function associated with inappropriate calcium, phosphorus and vitamin D metabolism. Radiographic findings are among tools used to diagnose and monitor ROD.
The researchers advised that dental treatment should emphasize oral hygiene and patient self-care. They recommended symptomatic treatment, including oral antibiotics to prevent bacterial endocarditis and oral antifungals to prevent secondary candida infection.
Among conclusions, researchers said oral manifestations of systemic diseases are more frequent and “as dentists, we have a vital role in treating them accordingly.”
The aging of wisdom teeth
Radiographic examination of third molars is important in estimating patient age and in treatment planning. As these teeth grow, their roots lengthen, making them more difficult to remove and increasing the likelihood of complications.
Scientists at Pusan National University, in Yangsan, Korea, examined ways to aid decision making about saving or removing third molars, and to determine the best time for extraction, if necessary. They published their findings in the September 2014 issue of Imaging Science in Dentistry.
The scientists evaluated developmental stages of 7,081 wisdom teeth on 2,490 panoramic radiographs. Their purpose was to explore stages of development in wisdom teeth by age as well as differences between maxillary and mandibular teeth in males and females. The subject population of 2,490 patients, ranged in age from 6 to 28 years and included 1,273 males and 1,217 females, with an average age of 15.7 years. Subjects were randomly selected from among patients who had visited the university’s dental hospital and undergone panoramic radiographic examination in 2011.
Scientists used the modified Demirjian’s classification system, which distinguishes eight stages of crown and root development (A – H). The Demirjian system is recognized as the most accurate in correlating estimated and true age.
Results showed a strong positive relationship between the developmental stage of third molars and chronological age, with more advanced third molars in the upper arch than in the lower arch.
Also among major findings:
• males reached the developmental stages earlier than females, with significant gender differences in the last five developmental stages;
• average age of initial mineralization of the teeth was 8.57 years, and average age at apex closure was 21.96 years.
• average age of crown completion was 14.52 for upper wisdom teeth, and 15.04 for the lower teeth.
The average age of patients who had developed completed crowns (Stage D) was 14.77 years. Compared with reports for other populations, this was later than in an Iranian population and earlier than in Japanese or German populations.
One previous study reported that females reached Demirjian Stage D by 19 years of age at the latest and males reached it by 18 at the latest.
This latest study found that the maximum age at Stage D was 22 years, although crown completion was observed in 90 percent of the patients by the time they were 17 years old. Authors suggested the range could be explained by differences in the study populations.
ADA offers discount on X-ray exam brochure
Now through Dec. 15, the ADA is offering members free shipping on all patient education brochures with a minimum $75 order.
Members can order “Dental X-Ray Exams” (W566) through the ADA Catalog, using promo code 14370E. The six-panel brochure is available in packets of 50 for $26; retail price $39. Discounts also are available in higher quantities.
Written for the dental patient, the brochure reinforces the value of radiographs as a diagnostic tool. It makes the point that finding and treating dental problems at an early stage can save time and money, and prevent pain. The brochure features new X-ray images, assures patients of the safety of radiography and shows how dental offices take steps to reduce the amount of radiation exposure.
Members can preview this and other ADA brochures online at adacatalog.org. Orders can be placed online or by calling the ADA Member Service Center at 1-800-947-4746. Remember to use promo code 14370E to get free shipping with a minimum $75 order.
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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 fourth in the series on this topic for 2014. Other Specialty Scan issues are devoted to periodontics, orthodontics, endodontics and prosthodontics. 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 feedback on this and all Specialty Scan issues.
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