Evaluation of Cone-beam Computed Tomography Artifacts Produced by Metal Objects Located Within and Outside the Field of View.

INTRODUCTION: Artifacts created by the presence of metal objects in the jaw negatively affect the cone-beam computed tomographic image quality. This study compares artifacts produced by metal objects outside of the field of view (FOV) in a small FOV CBCT image with those produced in a large FOV image in which the metal object is within the FOV. METHODS: We methodically placed 4 titanium implant-sized rods and 4 zirconium crown-sized disks on 1 side of a human cadaver mandible. Using the Accuitomo 170 CBCT machine (J Morita, Irvine, CA), a total of 18 scans (9 with a small FOV and 9 with a large FOV) were made. Ten axial slices from each scan were transferred to ImageJ software (National Institutes of Health, Bethesda, MD) for analysis. The mean standard deviation of all voxel values of a fixed region of interest (ie, uniform air located lingual to tooth #30) was compared between small and large FOV slices. Two blinded observers subjectively rated the images for diagnostic quality and the presence of artifacts. RESULTS: The Wilcoxon signed rank test showed that the standard deviation for both small and large FOV slices increases as the number of metal objects increases. The mean of the standard deviation for small and large FOVs is 3.6 and 2.5, respectively (P = .0000). Fifty-three percent of the small FOV slices had more artifacts in the subjective analysis. One hundred percent of the small FOV slices were rated as higher quality. CONCLUSION: Metal objects outside of the FOV in the contralateral quadrant do affect the quality of small FOV images. However, small FOV images have a higher resolution compared with large FOV images.

Dynamics of Bone Loss in Cases with Acute or Chronic Apical Abscess.

INTRODUCTION: Acute and chronic apical abscesses are 2 dramatic ways that periradicular tissues may react to pulpal infection and necrosis. Although both of these clinical states are the response to pulpal infection, their clinical manifestations are significantly different. It is not clear why the body responds to root canal infection in one way or another. The objective of this study was to evaluate the size and pattern of bone loss in patients with acute apical abscess (AAA) and chronic apical abscess (CAA) using cone-beam computed tomographic images. METHODS: Twenty-three cone-beam computed tomographic images of cases with AAA and 25 cases with CAA were selected and evaluated. The presence and location of fenestration and the volume and pattern of the periradicular lesions were recorded and compared between the 2 groups using the Fisher exact and Mann-Whitney U tests. RESULTS: One hundred percent of cases with CAA had cortical fenestration, but only 47% of cases with AAA had cortical fenestration (P < .05). The median volume of the lesions was 233 mm3 in the CAA group and 109 mm3 in the AAA group (P > .05). CAA cases, in comparison with the AAA group, had a relatively larger cortical disruptions. CONCLUSIONS: Cortical fenestration is fundamental for the development of CAA. However, periradicular lesions without evident cortical fenestration can still cause AAA and fascial space involvement.

Role of Cone-Beam Computed Tomography in the Management of Periodontal Disease.

The goal of this paper was to review the current literature surrounding the use of cone beam computed tomography (CBCT) related to the diagnosis, prognostic determination, and treatment of periodontal diseases. A literature review was completed to identify peer-reviewed articles related to CBCT and periodontics. The results were filtered to pool only articles specific to CBCT and periodontal diagnosis, prognosis, and treatment/outcomes. The articles were reviewed and findings summarized. Author's commentary on technological advances and additional potential uses of CBCT in the field of periodontics were included. There is evidence to suggest that CBCT imaging can be more accurate in diagnosing specific periodontal defects (intrabony and furcation defects), and therefore be helpful in the prognostic determination and treatment planning. However, at this time, CBCT cannot be recommended as the standard of care. It is up to the individual clinician to use one's own judgment as to when the additional information provided by CBCT may be beneficial, while applying the As Low As Reasonably Achievable (ALARA) principle. With continued technological advances in CBCT imaging (higher resolution, reduced imaging artifacts, lower exposure, etc.) the author's believe that CBCT usage will become more prominent in diagnosis and treatment of periodontal diseases.

Prevalence of Middle Mesial Canals and Isthmi in the Mesial Root of Mandibular Molars: An In Vivo Cone-beam Computed Tomographic Study.

INTRODUCTION: Many studies have investigated the morphology of the mandibular molar, but the prevalence of the middle mesial (MM) canal in the mesial root of the mandibular molar is still the subject of controversy. In addition, in previous literature, a true MM canal has not been clearly distinguished from an isthmus between the mesiobuccal and mesiolingual canals. Therefore, the objectives of this study were 2-fold: METHODS: Ninety limited field of view cone-beam computed tomographic scans were observed. One hundred twenty-two mature mandibular first and second molars with no previous root canal treatment, no root resorption, and intact crowns were retrospectively evaluated. Data regarding the sex, age, presence of MM canals, and number of root canals in the mesial root were recorded. RESULT: Of the 122 teeth, 20 (16.4%) had true MM canals. The prevalence of MM canals was 26% in first molars and 8% in second molars (P < .05). The frequency of isthmi in the mesial roots was 64.7%. The frequency of isthmi was higher in second molars, but the difference was not statistically significant (P > .05). CONCLUSIONS: This study showed a high prevalence of mandibular molars with MM canals or isthmi. The detection and biomechanical cleaning of these areas during nonsurgical or surgical root canal treatment are critical.