Influence of Cone Beam Computed Tomography Settings on Implant Artifact Production: Zirconia and Titanium.

PURPOSE: This in vitro study assessed the artifact production related to titanium and zirconia implants in cone beam computed tomography (CBCT) and compared the effect of different protocol settings on image quality for both materials. MATERIALS AND METHODS: A titanium implant and a zirconia implant were placed in a dry mandible. CBCT scans were obtained separately for each implant using the ProMax 3D (Planmeca) unit; 20 protocols were tested with varying kilovoltage (70 to 90 kVp) and resolution (high and low), and with and without a metal artifact reduction tool. Standard deviation and contrast-noise ratio were calculated in regions of interest adjacent and distant to the implant. RESULTS: The zirconia produced more artifacts and its images were more affected by the different protocols than titanium. High kVps and an activated metal artifact reduction tool decreased the standard deviation values related to both implants. Activation of the metal artifact reduction tool also increased contrast-noise ratio values for both implants, whereas increasing kVp improved them only on titanium images. The standard deviation and contrast-noise ratio were not affected by resolution. CONCLUSION: The zirconia implant generated more image artifacts than the titanium implant. Increasing kVp and the metal artifact reduction tool are efficient in decreasing the CBCT artifacts for both implants, whereas resolution does not affect their production.

Cone beam computed tomography image optimization to detect root fractures in endodontically treated teeth: an in vitro (phantom) study.

OBJECTIVES: The aim of this study was to evaluate the effect of an optimization filter (OF) and voxel size on the accuracy of root fracture detection. STUDY DESIGN: Half of 40 endodontically treated roots were fractured, and the other half were left intact. All teeth were randomly placed into 5 bovine ribs. Each rib was scanned with the Planmeca ProMax 3-D using 4 different settings: 75 µm and 100 µm voxel size with and without an OF. Five reviewers reported if a fracture was present by using a 5-point scale. Intra-/interobserver agreement, area under the receiver operative characteristic curve, accuracy, sensitivity, and false-positive rates were analyzed. RESULTS: High κ-values indicated strong intra-/interobserver agreement. There was no significant difference in fracture detection between any of the evaluated techniques. CONCLUSIONS: Because of the decreased cost, dose area product, and time required, compared with the other imaging modalities studied, the high-resolution mode (100 µm) without an OF is recommended for root fracture detection in endodontically treated teeth.

Evaluation of artifacts generated by zirconium implants in cone-beam computed tomography images.

OBJECTIVE: To evaluate zirconium implant artifact production in cone beam computed tomography images obtained with different protocols. STUDY DESIGN: One zirconium implant was inserted in an edentulous mandible. Twenty scans were acquired with a ProMax 3D unit (Planmeca Oy, Helsinki, Finland), with acquisition settings ranging from 70 to 90 peak kilovoltage (kVp) and voxel sizes of 0.32 and 0.16 mm. A metal artifact reduction (MAR) tool was activated in half of the scans. An axial slice through the middle region of the implant was selected for each dataset. Gray values (mean ± standard deviation) were measured in two regions of interest, one close to and the other distant from the implant (control area). The contrast-to-noise ratio was also calculated. RESULTS: Standard deviation decreased with greater kVp and when the MAR tool was used. The contrast-to-noise ratio was significantly higher when the MAR tool was turned off, except for low resolution with kVp values above 80. Selection of the MAR tool and greater kVp resulted in an overall reduction of artifacts in images acquired with low resolution. CONCLUSIONS: Although zirconium implants do produce image artifacts in cone-bean computed tomography scans, the setting that best controlled artifact generation by zirconium implants was 90 kVp at low resolution and with the MAR tool turned on.

Contrast-to-noise ratio with different settings in a CBCT machine in presence of different root-end filling materials: an in vitro study.

OBJECTIVES: To compare the contrast-to-noise ratio (CNR) of multiple acquisition settings for four types of retrograde filling materials in CBCT images taken for endodontic surgery follow-up. METHODS: 20 maxillary central incisors were endodontically treated and obturated with 4 different root-end filling materials: amalgam, mineral trioxide aggregate, SuperEBA(™) (Harry J Bosworth Company, Skokie, IL) and Biodentine™ (Septodont, Saint-Maur-des-Faussés, France). Teeth were placed in a skull and scanned, one by one, with the Planmeca ProMax(®) 3D Max (Planmeca, Helsinki, Finland); at different voltages: 66, 76, 84 and 96 kVp; with low, normal and high resolution and high definition (HD); with and without metal artefact reduction (MAR). Images were analyzed using ImageJ software (National Institutes of Health, Bethesda, MD) to calculate the CNR. The dose-area product was registered, and the effective dose calculated. RESULTS: No statistically significant difference was noted between the four materials. 84 and 96 kVp with low resolution and the use of MAR-generated images that have statistically better CNR than 66 and 76 kVp with HD, normal and high resolutions and without MAR. The use of low resolution also generated the smallest value of effective dose. CONCLUSIONS: The best setting for radiographic follow-up in an endodontic surgery with retrograde filling on the Planmeca ProMax is 96 kVp with low resolution and high MAR; this setting produced one of the lowest effective doses.

Evaluation and Reduction of Artifacts Generated by 4 Different Root-end Filling Materials by Using Multiple Cone-beam Computed Tomography Imaging Settings.

INTRODUCTION: After endodontic surgery, radiographic assessment is the method of choice to monitor bone defect healing. Cone-beam computed tomography scans are useful to check and identify the reasons of failure of surgical intervention or confirm healing; however, the artifact generated by some root-end filling material might compromise this task. The objective of the study was to compare the amount of artifacts generated by 4 root-end filling materials and to test multiple exposure settings used with these materials, when the effective dose generated by each protocol was taken into consideration. METHODS: Twenty central incisors were endodontically treated with retrograde obturation by using amalgam, Biodentine, MTA, and Super-EBA (5 of each). They were placed in a skull with soft tissue simulation and scanned by using the Planmeca Promax Max with different kilovolt peaks (kVp): 66, 76, 84, and 96 with and without the use of metal artifact reduction (MAR) algorithm and with low, normal, and high resolution and high definition. The Dose Area Product was registered, and the effective dose was calculated. RESULTS: Amalgam generated the highest amount of artifacts, whereas MAR and low resolution created fewer artifacts than other settings. The artifacts were also reduced with 96 kVp. The effective dose calculated with low resolution was remarkably lower than other resolutions. CONCLUSIONS: When used as root-end filling material, Biodentine, MTA, and Super-EBA generated fewer artifacts than amalgam. The use of 96 kVp with MAR and low resolution also reduced artifacts on the image and at the same time generated the lowest effective dose.

Location of Posterosuperior Alveolar Artery and Correlation with Maxillary Sinus Anatomy.

The blood supply to both the lateral wall of the maxillary sinus and the overlying membrane originates from the posterosuperior alveolar artery (PSAA) and the infraorbital artery. The purpose of the present study was to evaluate the anatomic characteristics of the PSAA in a large number of subjects of the Lebanese population. Images of 696 sinuses were analyzed using cone beam computed tomography (CT). Coronal, axial, and sagittal CT images were evaluated for the presence of an osseous canal in the lateral wall of the sinus, and the prevalence, position, and location of the canal were studied and presented.

Number of basis images effect on detection of root fractures in endodontically treated teeth using a cone beam computed tomography machine: an in vitro study.

OBJECTIVES: The objective of this study was to compare the accuracy of root fracture detection in endodontically treated teeth using scans acquired with a 180° rotation motion compared with a 360° after which the patient exposure and number of basis images are doubled. METHODS: Sixty-six roots were collected and decoronated. All were treated endodontically. One-half of the roots were fractured, resulting in 2 root fragments which were then glued together. The roots were placed randomly in 8 prepared beef rib fragments. Five reviewers independently reviewed the scans twice, at different times. RESULTS: The specificity of the 360° scan was significantly higher than the 180° scan; doubling the basis images leads to a significant decrease in false-positive rates. Accuracy and sensitivity were not significantly different. CONCLUSIONS: Only the specificity is improved by the increased rotation and doubling of images. The accuracy and sensitivity are not improved.

Contrast-to-noise ratio difference in small field of view cone beam computed tomography machines.

Each of three cone beam computed tomography (CBCT) machines offer a small field of view (FOV); Promax, Accuitomo 3D, and Kodak 9000. The objectives were to determine, when using a small FOV, the difference in contrast-to-noise ratios (CNR) of images obtained from different machines and different scan settings within each machine. A phantom made of a dry mandible with an epoxy resin based substitute (ERBS) block was used. The ERBS block was fixed to the lingual cortex in the posterior left mandible. Water was used to simulate soft tissue. Twenty scans were acquired. CNR was calculated as the difference in density of the ERBS block and a control area divided by the standard deviation of the difference. The CNR obtained from images acquired with the Promax machine (voxel size of 0.2 mm) was higher than the other machines (voxel sizes 0.076, 0.08, or 0.125 mm) when using a small FOV. The Accuitomo 360° scan had higher CNR than the Accuitomo 180° scan due to the doubling of the number of basis images acquired. Smaller voxel size does not necessarily lead to enhanced CNR. Increasing the number of basis images did increase the CNR.

Contrast-to-noise ratio with different large volumes in a cone-beam computerized tomography machine: an in vitro study.

OBJECTIVES: The objectives were to determine whether the images obtained from different cone-beam computerized tomography (CBCT) field of view (FOV) sizes with varying scan time and kilovolt peak using the Picasso Master 3D machine (Vatech, Hwasung, South Korea) differ in contrast-to-noise ratio (CNR). STUDY DESIGN: A phantom was used. Scans were acquired using the same voxel size, 2 scan times (15 and 24 seconds) for 3 different FOV sizes and 5 different kilovolt peaks. The contrast and CNR were calculated for each FOV. RESULTS: The CNRs were similar for the 2 scan times for all 3 FOV sizes. The CNR was lower in the 20 × 19 cm FOV compared with the other 2 FOVs for both scan times. CONCLUSIONS: The CNR does not vary significantly with increasing scan times for all FOV sizes. Smaller FOVs result in enhanced CNR and contrast.

Effect of JPEG compression on the diagnostic accuracy of periapical images in the detection of root fracture.

The ability of a periapical radiograph to exhibit the fracture depends on many factors including, but not limited to, the resolution of the image. The quality can be reduced by the image compression. The purpose of this study is to evaluate the effect of Joint Photographic Experts Group (JPEG) compressions on the diagnostic capability of periapical images in the detection of root fractures. Ten dry human mandibles containing 151 teeth were used in this study. Mandibles were radiographed with direct digital imaging sensor using the paralleling technique. Four observers detected root fracture on the images saved in one uncompressed and two compressed formats. Receiver operating characteristic (ROC) and anova analyses were performed to compare the performance of the three different systems and evaluate the effect of the compression on the accuracy of root fracture detection. Results did not show any statistically significant difference between the original, large images presented in tagged image file format (TIFF) and the two compressed images (JPEG medium file and JPEG small file images) in the detection of root fractures. The intra-rater comparison showed a significant consistency in the detection of the fracture. The compression reduced the file size considerably (from 1.77 MB to 453 and 95 Kb), but it did not affect the accuracy of root fracture detection. The file size reduction, on the other hand, is very beneficial for image electronic storage and mainly in teleradiology.

Comparison of the fit of Procera crowns made from stone with those made from polyurethane resin.

This study compared the average marginal gap of Procera crowns fabricated from a definitive cast made from polyurethane resin with those made from type IV stone. A metallic maxillary central incisor and first premolar were prepared according to the Procera guidelines and incorporated into a U-shaped definitive cast. From this definitive cast, 20 primary casts were made in polyurethane resin. Two sets of impressions (10 with type IV stone and 10 with polyurethane resin) were made and poured onto these casts. Forty pure aluminum oxide substructures for Procera crowns were made for these groups, with 10 incisors and 10 premolars in each group. Each substructure was cemented on the respective primary die and sectioned. Using an optical microscope and special software, sections were measured and compared for marginal adaptation. Based on the findings, both materials were equally adequate for producing a Procera crown. However, the mean margin gap was consistently larger for type IV stone dies than for polyurethane resin dies.