Do cone-beam computed tomography low-dose protocols affect the evaluation of the temporomandibular joint?

BACKGROUND: There is no established acquisition protocol based on scientific evidence for the acquisition of cone-beam computed tomography (CBCT) exams to evaluate the temporomandibular joint (TMJ). OBJECTIVES: To evaluate the influence of acquisition protocols and jaw positioning on the diagnostic accuracy of TMJ condylar morphological alterations (CMA), dimension, position and excursion. METHODS: Thirty-six TMJs on 18 dry skulls were imaged using a CBCT unit (OP300 Maxio, Instrumentarium, Tuusula, Finland) at two exposure settings (4.5 and 6.3 mA), three voxel resolutions (0.085, 0.125 and 0.280 mm), three jaw positions (concentric, anteriorised and posteriorised) and three jaw excursions (normoexcursion, hyperexcursion and hypoexcursion). The macroscopic anatomy examination and high-resolution CBCT images were used as ground truth for CMA. Twenty-five TMJs had at least one CMA with 11 healthy TMJs serving as controls. Three experienced oral and maxillofacial radiologists evaluated the parasagittal images for the presence of CMA, position and excursion and measured dimensions. The area under the ROC curve, sensitivity and specificity were calculated. Weighted Kappa (α = 0.05) was used to determine intra- and interexaminer reliability and comparisons between dependent variables analysed by Analysis of Variance at an a prior level of significance of 0.05. RESULTS: The agreement of the evaluation of the position and excursion with the reference standard was high, independent of the protocol (range, 0.75-0.91). Various combinations of acquisition protocols and jaw position did not influence the CMA evaluation. Erosion was overdiagnosed in protocols with larger voxel sizes and the detection of osteophytes greater in images with smaller voxel sizes. The anteroposterior dimension was greater in the open jaw position (p < .05). CONCLUSION: CBCT protocols using reduced radiation exposure from the CBCT machine evaluated in this study can be used to assess condylar morphology, dimension, position and excursion, without compromising diagnostic performances for these parameters.

Does enhancement filter application increase the diagnostic accuracy of misfit detection at the implant-prosthesis interface?

STATEMENT OF PROBLEM: Misfits at the implant-prosthesis interface may increase complications in dental implants and affect peri-implant tissue health. Periapical radiographs are the most used imaging examinations for detecting misfits at the implant-prosthesis interface, although digital systems have largely replaced film-based radiographs. Whether postprocessing tools such as enhancement filters assist diagnosis by highlighting misfits is unclear. PURPOSE: The purpose of this in vitro study was to assess the influence of enhancement filter application in the diagnostic accuracy of misfit detection at the implant-prosthesis interface. MATERIAL AND METHODS: A total of 32 dental implants were placed in dry human mandibles. A polyester strip was inserted at the implant-prosthesis interface to simulate a 50-µm misfit; prosthetic crowns installed directly on the implant platforms were used as controls. Standard paralleling periapical images were acquired by using a semidirect system (photostimulable phosphor plate) with the application of Highlight, Invert, and Colorization filters, as well as a direct system (metal oxide complementary semiconductor sensor) with filters Sharpness 3, Invert, and Pseudocolorization. Oral radiologists evaluated the images with and without the application of filters. The areas under the receiver operating characteristics curves (Az values), sensitivity, specificity, accuracy, positive predictive value, and negative predictive values were calculated. The Az values were compared with the receiver operating characteristic (ROC) curves comparison test of the Epidat 3.1 software (α=.05). RESULTS: Although images without filter application presented descriptively higher diagnostic values than those with filter application, the Az values for images with and without filter application in both semidirect and direct systems showed no significant differences (P>.05). CONCLUSIONS: Enhancement filter application did not significantly influence the diagnostic accuracy of misfit detection at the implant-prosthesis interface.

Influence of Voxel Size and Filter Application in Detecting Second Mesiobuccal Canals in Cone-beam Computed Tomographic Images.

INTRODUCTION: This study assessed the influence of voxel size and filter application in detecting second mesiobuccal (MB2) canals in cone-beam computed tomographic (CBCT) images. METHODS: Using the OP300 CBCT system (Instrumentarium, Tuusula, Finland) and 3 voxel size protocols (80 µm, 125 µm, and 200 µm), we scanned 40 first molars: 20 with an MB2 canal and 20 without. All molars received silver palladium pins on the palatal root, whereas the non-MB2 molars were also filled with gutta-percha. Five oral radiologists assessed the presence of an MB2 canal under 3 filter application conditions: without filter, with sharpen 1 × filter, and with sharpen 2 × filter. Intra- and interobserver reproducibility was evaluated using the weighted kappa index. We compared the area under the receiver operating characteristic curves with SPSS Statistics v.20.0 (IBM Corp, Armonk, NY) using 2-way analysis of variance and the Tukey post hoc test with 5% significance level. RESULTS: Our analysis found median intra- and interobserver agreement values of 0.70 and 0.56, respectively. The 80-µm voxel with sharpen 1 × filter image group had the highest sensitivity, accuracy, and negative predictive values. As for specificity and positive predictive, the 80-µm voxel group without filter application presented the highest values. The areas under the receiver operating characteristic curve were higher in the 80-µm groups than in the 125-µm and 200-µm voxel size groups (P < .05). We found no differences among the filters used (P = .22) or for the filter-voxel size interactions (P = .88). CONCLUSIONS: A smaller voxel size increased the accuracy in detecting MB2 canals, whereas the enhancement filters did not.