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JADA Specialty Scan - Radiology
 
Radiology - A Quarterly Newsletter on Dental SpecialtiesJADA Specialty Scan

Assessing mandibular anatomy using cone-beam computed tomography

Before placing implants or performing surgery in the anterior segment of the mandible, clinicians need complete information about the anatomy in this region to minimize the possibility of neural trauma and its sequelae. In this retrospective cross-sectional study published in the March issue of Journal of Dentistry of Tehran University of Medical Sciences, researchers evaluated the location and characteristics of the mental foramen, anterior loop, and mandibular incisive canal using cone-beam computed tomography (CBCT).

The investigators examined 200 CBCT scans of patients (110 women and 90 men) referred to a private radiology clinic. All of the scans were obtained using the same CBCT unit (ProMax 3D, Planmeca) using exposure settings of 84 kilovolts (peak), 14 milliamperes, 12 seconds’ duration, 8X8-centimeter field of view, and 0.16 mm voxel size.

The most common locations of the mental foramen were along the second premolar and between the second and first premolars. In 71% of cases, the mental foramina were located symmetrically on the right and left sides. In 45% of cases, they were located along the second premolar on both sides. The inferior alveolar neurovascular bundle often ascends for a few millimeters before curving back to the mental foramen; this is known as the anterior loop. Researchers observed the anterior loop in 59.5% of scans (bilateral in 39% and unilateral in 20.5%). The anterior loop was found in 65% of men and 54.5% of women.
CBCT scans showed the mandibular incisive canal in 97.5% of cases (bilateral in 94% and unilateral in 3.5%). Researchers noted that the canal was lower than the mental foramen in 74.6% of cases on the right side and in 81% of cases on the left side (P < .01).

When comparing the results for men with those for women, the investigators found shorter distances from the end point of the mandibular incisive canal to the buccal plate in the scans from women, as well as from the end point of the canal to the inferior border of the mandible. They attributed these differences to the smaller mandibular dimensions in women. Only one variable—distance from the end point of the canal to the buccal plate—was directly correlated with age, but this correlation was relatively weak.

Researchers conclude that because of the variability in size and position of the mandibular incisive canal and the high prevalence of anterior loop, CBCT is recommended before surgical manipulation of the interforaminal region.

Read the original article.

 

Consulting Editor: Laurie C. Carter, DDS, PhD
Past president, American Academy of Oral and Maxillofacial Radiology

Examining osteonecrosis of the jaw in two patient populations

The pathophysiology of osteonecrosis of the jaw (ONJ) is unclear, but it appears to be multifactorial, with infection playing a key role. Researchers present a case-based review of ONJ and apply recommendations from the International Task Force on ONJ in an article published online December 9 in Journal of Clinical Densitometry: Assessment & Management of Musculoskeletal Health.

Among the questions posed is this: Why does ONJ develop? “It is not known whether necrosis precedes or follows infection,” the authors stated. “Infection and inflammation clearly play a significant role in the development of ONJ.” Bisphosphonates may increase the risk of local infection and contribute to impaired healing of the oral mucosa. In addition, suppression of bone remodeling by bisphosphonates and denosumab may contribute to ONJ.
The prevalence of ONJ in patients with osteoporosis is low (about 0.001-0.01%), according to estimates from surveys conducted in several countries. In patients receiving treatment with bisphosphonates or denosumab, the risk of developing ONJ appears to be “only slightly higher than the risk in the general population,” the authors reported.

However, in oncology patient populations, the incidence of ONJ is much higher than that in osteoporosis patient populations. The researchers pointed to a recent meta-analysis that reported a 1.7% incidence of ONJ in patients with cancer receiving denosumab treatment and an incidence between 1% and 15% in those receiving treatment with high-dose bisphosphonates, possibly tied to dose and duration of exposure. There may be confounding variables in this population, including use of other drugs that affect bone health, as well as other risk factors for ONJ such as chemotherapy, diabetes mellitus, poor dental hygiene, tooth extraction, neutropenia, and pre-existing local infection.
Intravenous (IV) bisphosphonate and denosumab therapy in patients with cancer involves doses that are 12 to 15 times higher than oral doses of these drugs used to treat osteoporosis. However, bisphosphonate and denosumab therapy results in a clinically significant reduction in the risk of skeletal-related events such as progression of metastatic bone deposits in people with cancer in comparison with the relatively low risk of developing ONJ, the researchers stress. Thus, the benefits of high-dose antiresorptive therapy far outweigh the risk of ONJ.

The role of imaging in detecting and managing ONJ also was examined. Plain radiographs aided in evaluating the presence of early changes, such as thickening of the lamina dura and increased trabecular density of the alveolar bone. However, only a small portion of the mandible or maxilla could be assessed by means of conventional radiography. Computed tomography (CT) has many advantages over plain radiographs, including the ability to assess the cortical and trabecular architecture of the jaws and periosteal reactions. Cone-beam computed tomography (CBCT) offers the advantages of CT at a significantly lower radiation exposure. The authors stressed the importance of early detection of dental disease in patients receiving high-dose IV bisphosphonate or denosumab treatment in whom the risk of developing ONJ is significant. They recommend use of CBCT in these patients because of its superiority to conventional radiography in diagnosing periapical and periodontal diseases.

For oncology patients, invasive dental procedures such as tooth extraction and implant placement should be performed before initiation of high-dose IV bisphosphonate or denosumab therapy. Nonurgent dental procedures should be delayed if possible. Patients with osteoporosis who receive bisphosphonate or denosumab treatment can undergo needed dental procedures, including extractions and implant placement. The task force’s opinion was that decisions to continue or withhold antiresorptive therapy should be made jointly by the dental care provider and the patient’s physician, in keeping with current understanding of ONJ.

Treatment depends on the disease stage, lesion size, contributing drug therapy, and medical and pharmacologic comorbidities, the authors reported. Conservative therapy focuses on improving oral hygiene, treating active dental disease, using topical antibiotic mouthrinses, and initiating systemic antibiotic treatment. Surgery, including osteotomy of the affected area, should be considered for patients who do not respond to conservative treatment. The researchers concluded that the diagnostic and prognostic factors for ONJ need to be further refined to better identify patients at high risk of developing ONJ.

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ADA brochure explains X-ray exams to patients

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To help reinforce the value of radiographs as a diagnostic tool, the ADA offers the patient education brochure, “Dental X-Ray Exams.” This brochure explains how finding and treating dental problems at an early stage can help save time and money and prevent pain. 

Featuring vivid photos of the different types of dental radiographs, this reference explains how each of these types might be important in their dental exam. In addition, patients will have an understanding of the types of problems that dental practitioners can find when using X-rays. It assures patients of the safety of S-rays and that dental offices take steps to reduce the amount of radiation to which patients are exposed.       

“Dental X-Ray Exams” is a 6-panel brochure available in packs of 50 from the ADA Catalog. A sample can be viewed here. To order, call 1-800-947-4746 or go to adacatalog.org. Readers who use the code 17402E before February 10 can save 15 percent on all ADA Catalog products.

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  • Duis molestie, purus eu pharetra consequat, quam nulla suscipit ante, sodales luctus elit dui id elit.
  • Donec justo ante, pulvinar vel elit nec, accumsan tempor diam.
  • Sed posuere diam ac molestie condimentum.
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Morbi sit amet velit at ligula facilisis tincidunt a in enim. Interdum et malesuada fames ac ante ipsum primis in faucibus. Nunc vel arcu nibh. Nulla in pharetra ante. Duis condimentum vel quam vel rhoncus. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nulla non cursus leo, rutrum auctor leo. Cras consequat dolor eros.

 
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elit.Nam tincidunt eget mauris ac lacinia. Sed non nibh mauris. Curabitur congue condimentum urna in luctus. Duis consectetur orci dignissim eros fermentum adipiscing. Nulla facilisi. Interdum et malesuada fames ac ante ipsum primis in faucibus.

 

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 first in the series on this topic for 2017. Other Specialty Scan issues are devoted to endodontics, oral pathology, orthodontics, pediatric dentistry, periodontics and prosthodontics. The ADA has engaged the specialty organizations in these areas as well as its own Science Institute and Division of Legal Affairs to assist with these newsletters. We welcome feedback on this and all Specialty Scan issues.

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Any statements of opinion or fact are those of the authors and do not necessarily reflect the views of the American Dental Association. Neither the ADA nor any of its subsidiaries have any financial interest in any products mentioned in this publication. Any reference to a product or service, whether in advertisements or otherwise, is not intended as an endorsement or as approval by the ADA or any of its affiliated organizations unless accompanied by an authorized statement that such approval or endorsement has been granted.

All matters pertaining to advertising should be addressed to the advertising sales manager, Sales and Marketing Department, American Dental Association, Publishing Division, 211 E. Chicago Ave., Chicago, IL 60611, 1-312-440-2740, fax 1-312-440-2550. All advertising appearing in ADA publications must comply with official published standards of the American Dental Association, a copy of which is available on request.