The impact of CBCT-head tilting on 3D condylar segmentation reproducibility.

OBJECTIVES: To investigate whether variations in head positioning may influence the reproducibility of cone-beam CT (CBCT) three-dimensional (3D) segmented models of the mandibular condyle. METHODS: Five fresh frozen cadaver heads were scanned in four different positions: reference position (RP) and a set of three tilted alternative head positions (AP) in anteroposterior direction (AP1: 2 cm anterior translation, AP2: 5° pitch rotation, AP3: 10° pitch rotation). Surface models of mandibular condyles were constructed and compared with the condylar reference position using voxel-based registration. Descriptive statistics and a linear mixed-effects model were performed to compare condylar volumetric differences and root mean square (RMS) distance between surfaces of AP vs RP. RESULTS: The mean differences in condylar volumes of AP vs RP were 14.1 mm³ (95% CI [-79.3, 107.4]) for AP1, 1.0 mm³ (95% CI [-87.2, 89.2]) for AP2 and 0.1 mm³ (95% CI [-88.3, 88.4]) for AP3. Mean and absolute volumetric differences did not exceed earlier reported intraoperator differences of 30 mm³. The RMS distance values obtained per group were 0.12 mm (95% CI [0.05,0.20]) for AP1, 0.17 mm (95% CI [0.10, 0.22]) for AP2 and 0.17 mm for AP3 (95% CI [0.10,0.22]). The confidence intervals (CI) for RMS distance remained far below the threshold for clinical acceptability (0.5 mm). CONCLUSIONS: Within the limits of the present study, it is suggested that tilted head positions may affect the reproducibility of 3D condylar segmentation, thereby influencing outcome in repeated CBCT scanning. Nevertheless, observed differences are unlikely to have a meaningful impact on clinical patient diagnosis and management.

Feasibility of photon-counting computed tomography as a novel imaging modality for challenging endodontic diagnostic tasks.

Photon-counting computed tomography (PCCT) is an innovative technological advancement in relation to x-ray detectors which offers ultra-high-resolution images. The current study aimed to evaluate the visualization ability of PCCT compared to cone-beam computed tomographic (CBCT) devices for challenging endodontic diagnostic tasks. A reference image of an anthropomorphic phantom was acquired using an industrial micro-CT device. Thereafter, the phantom was scanned with three imaging devices, which included PCCT scanner (NAEOTOM Alpha) and two CBCT devices (3D Accuitomo 170 and NewTom VGi evo) having standard and high-resolution acquisition protocols. The diagnostic tasks involved visualizing fine endodontic structures (apical delta, narrow canal, and isthmus) and root cracks. Three experienced examiners assessed the images and were blinded to the PCCT and CBCT devices. Each image was rated according to a three-grade scale (appropriate, acceptable, or inappropriate) for the diagnostic tasks. In relation to fine endodontic structures grouped together, PCCT showed similar diagnostic performance compared to the reference image (p > 0.05). As for the CBCT devices, an excellent performance was only observed with the 3D Accuitomo 170 device at a high-resolution acquisition mode (p > 0.05). The visualization of root cracks was also better with 3D Accuitomo 170 compared to other devices (p < 0.05). Overall, PCCT and 3D Accuitomo 170 at a high-resolution setting showed similar performance for visualizing fine endodontic structures. In addition, the high-resolution CBCT protocol was superior for visualizing root cracks compared to both PCCT and other standard- and high-resolution CBCT protocols.

Image quality for visualization of cracks and fine endodontic structures using 10 CBCT devices with various scanning protocols and artefact conditions.

The aim of this study was to evaluate CBCT exposure protocols and CBCT devices in terms of image quality for the detection of cracks and fine endodontic structures using 3 conditions of metallic artifacts. An anthropomorphic phantom containing teeth with cracks, isthmus, narrow canal, and apical delta was scanned using ten CBCT devices. A reference industrial CT image was used to detect and measure all structures. Three conditions were created: (1) metal-free, (2) 'endo' and (3) 'implant' with metallic objects placed next to the teeth of interest. For each condition, three protocols were selected: medium field of view (FOV) standard resolution, small FOV standard and high resolution. The results showed that only small FOV high-resolution metal-free images from two devices (A and H) were appropriate to visualize cracks. For fine structure identification, the best result was observed for small FOV high resolution. However, the visualization significantly worsened in the presence of metallic artefacts. The ability of CBCT images for visualizing cracks is restricted to certain CBCT devices. Once metallic artefacts are present, crack detection becomes unlikely. Overall, small FOV high-resolution protocols may allow detection of fine endodontic structures as long as there are no high-dense objects in the region of interest.

Effect of foraminal enlargement on microcrack formation and apical transportation: a nano-CT assessment.

The aim of this study was to evaluate the foraminal enlargement and its influence on microcrack formation and apical transportation in root canals with apical curvature. Eighteen maxillary lateral incisors with apical curvature were selected by using micro-CT images. Root canals were randomly divided in two groups (n = 9) according to root canal preparation using two working lengths: 1 mm short of the apical foramen (control group) and 1 mm beyond the apical foramen (foraminal enlargement). For both groups Reciproc Blue R40 was used for root canal instrumentation. Specimens were scanned by nano-CT (UniTOM HR) before and after root canal preparation. Percentage, length, and width of microcracks, and apical transportation were assessed. Kappa, chi-square and McNemar tests were used for qualitative analyses while paired and unpaired t-test were used for quantitative analyses (α = 0.05). For both groups, rather similar and low percentages of microcracks were observed before root canal preparation (P > 0.05). The foraminal enlargement promoted new microcracks, not observed in the control group. An increase in microcrack length was observed when the foraminal enlargement was performed (P < 0.05). Higher apical transportation was observed when foraminal enlargement was performed (P < 0.05). Foraminal enlargement using a heat-treated reciprocating file size 40 promoted microcracks and higher apical transportation than root canal preparation up to 1 mm short of apical foramen.

The impact of implant-related characteristics on dental implant blooming: An in vitro study.

AIM: To assess, in vitro, variables potentially influencing implant blooming using a human-like imaging phantom and 3D-printed mandibles. MATERIAL AND METHODS: Sixty implants were inserted in 3D-printed mandibles in 26 different configurations in order to examine the impact of implant diameter, presence of a cover screw, implant design/material, implant position, and the presence of additional implants on implant blooming using two cone-beam computed tomography (CBCT) devices (Accuitomo [ACC] and NewTom [NWT]). Two observers measured the amount of implant blooming in both buccolingual and mesiodistal directions. Inter-rater agreement and descriptive statistics, grouped by implant characteristic and CBCT device, were calculated. RESULTS: Both CBCT devices increased implant diameter (a mean increase of 9.2% and 11.8% for titanium, 20.3% and 24.4% for zirconium, for ACC and NWT, respectively). An increase in implant diameter did not increase the amount of blooming, whereas placing a cover screw did (from 8.0% to 10.9% for ACC, and from 10.0% to 15.6% for NWT). Moreover, implant design, anatomical region, and the presence of another implant also affected the extent of the blooming. CONCLUSIONS: Dental implants show a clear diameter increase on CBCT, with the effect being more pronounced for zirconium than for titanium implants. Similar effects are likely to occur in the clinical setting, potentially masking nonosseointegration, reducing the dimensions of peri-implant defects, and/or causing underestimation of the buccal bone thickness.

Convolutional neural network for automatic maxillary sinus segmentation on cone-beam computed tomographic images.

An accurate three-dimensional (3D) segmentation of the maxillary sinus is crucial for multiple diagnostic and treatment applications. Yet, it is challenging and time-consuming when manually performed on a cone-beam computed tomography (CBCT) dataset. Recently, convolutional neural networks (CNNs) have proven to provide excellent performance in the field of 3D image analysis. Hence, this study developed and validated a novel automated CNN-based methodology for the segmentation of maxillary sinus using CBCT images. A dataset of 264 sinuses were acquired from 2 CBCT devices and randomly divided into 3 subsets: training, validation, and testing. A 3D U-Net architecture CNN model was developed and compared to semi-automatic segmentation in terms of time, accuracy, and consistency. The average time was significantly reduced (p-value < 2.2e-16) by automatic segmentation (0.4 min) compared to semi-automatic segmentation (60.8 min). The model accurately identified the segmented region with a dice similarity co-efficient (DSC) of 98.4%. The inter-observer reliability for minor refinement of automatic segmentation showed an excellent DSC of 99.6%. The proposed CNN model provided a time-efficient, precise, and consistent automatic segmentation which could allow an accurate generation of 3D models for diagnosis and virtual treatment planning.

Surgical guides for guided bone augmentation: An in vitro study.

AIM: To validate in vitro the accuracy of a novel method for bone augmentation of horizontal alveolar bone defects with the help of a surgical guide. MATERIAL AND METHODS: Six cone-beam computed tomography scans of patients requiring horizontal bone augmentation were segmented and 3D printed. Two surgeons performed the bone augmentation surgery twice for each case on 3D-printed models, using either a conventional or guided protocol. Each surgeon virtually planned the desired graft shape beforehand. The resulting grafts were compared linearly and volumetrically to the plan; graft density and surgical time were also analyzed. RESULTS: There was significantly less graft volume outside the planned volume with the guided protocol (36.8% ± 14.1 vs. 19.6% ± 12.3, p < .01). The use of a guide increased graft accuracy at several measurement points, resulting in less overfill when using the guided protocol (1.7 ± 1.7 mm at the most coronal point, 0.2 mm ± 1.4 at 25%, 0.0 mm ± 0.9 at 50%, 0.1 mm ± 1.1 at 75%, and 0.4 mm ± 1.4 apically). Graft thickness was increased 1 mm coronally from the planned graft (2.8 mm ± 2.3 vs. 1.8 mm ± 2.2, p = .04). Surgical time increased significantly when using a guide (a difference of 2 m 26 s). CONCLUSION: The technique, tested here in vitro, allows surgeons to improve the accuracy of the resulting graft shape, to better compact material in the coronal portion of the graft, and to reduce the amount of graft material placed outside the planned volume.

How do imaging protocols affect the assessment of root-end fillings?

Objectives: This study investigated the impact of micro-computed tomography (micro-CT)-based voxel size on the analysis of material/dentin interface voids and thickness of different endodontic cements. Materials and Methods: Following root-end resection and apical preparation, maxillary premolars were filled with mineral trioxide aggregate (MTA), Biodentine, and intermediate restorative material (IRM) (n = 24). The samples were scanned using micro-CT (SkyScan 1272; Bruker) and the cement/dentin interface and thickness of materials were evaluated at voxel sizes of 5, 10, and 20 µm. Analysis of variance and the Tukey test were conducted, and the degree of agreement between different voxel sizes was evaluated using the Bland and Altman method (p < 0.05). Results: All materials showed an increase in thickness from 5 to 10 and 20 µm (p < 0.05). When evaluating the interface voids, materials were similar at 5 µm (p > 0.05), while at 10 and 20 µm Biodentine showed the lowest percentage of voids (p < 0.05). A decrease in the interface voids was observed for MTA and IRM at 20 µm, while Biodentine showed differences among all voxel sizes (p < 0.05). The Bland-Altman plots for comparisons among voxel sizes showed the largest deviations when comparing images between 5 and 20 µm. Conclusions: Voxel size had an impact on the micro-CT evaluation of thickness and interface voids of endodontic materials. All cements exhibited an increase in thickness and a decrease in the void percentage as the voxel size increased, especially when evaluating images at 20 µm.

Impact of metal artefacts on subjective perception of image quality of 13 CBCT devices.

OBJECTIVES: The overall objective of this study was to assess how metal artefacts impact image quality of 13 CBCT devices. As a secondary objective, the influence of scanning protocols and field of view on CBCT image quality with and without metal artefacts was also assessed. MATERIALS AND METHODS: CBCT images were acquired of a dry human skull phantom considering three clinical simulated conditions: one without metal and two with metallic materials (metallic pin and implant). An industrial micro-CT was used as a reference to register the CBCT images. Afterwards, four observers evaluated 306 representative image slices from 13 devices, ranking them from best to worst. Furthermore, within each device, medium FOV and small FOV standard images were compared. General linear mixed models were used to assess subjective perception of examiners on overall image quality in the absence and presence of metal-related artefacts (p < 0.05). RESULTS: Image quality perception significantly differed amongst CBCT devices (p < 0.05). Some devices performed significantly better, independently of scanning protocol and clinical condition. In the presence of metal artefacts, medium FOV standard scanning protocols scored significantly better, while in the absence of metal, small FOV standard yielded the highest performance. CONCLUSIONS: Subjective image quality differs significantly amongst CBCT devices and scanning protocols. Metal-related artefacts may highly impact image quality, with a significant device-dependent variability and only few scanners being more robust against metal artefacts. Often, metal artefact expression may be somewhat reduced by proper protocol selection. CLINICAL RELEVANCE: Metallic objects may severely impact image quality in several CBCT devices.

Malignant tumours mimicking periapical lesions: A report of three cases and literature review.

Apical periodontitis shows radiographic signs such as widening of the periodontal ligament and periapical radiolucency, which differ in extent depending on the stage of the lesion. However, other lesions can be associated with or coincidental to the apical region, representing developmental lesions and benign or malignant tumours. This article describes three cases of malignant tumours, a central mucoepidermoid carcinoma (CMEC), a chondroblast osteosarcoma and an osteosarcoma of the jaw (OSJ) that presented as periapical lesions. Endodontists must be aware of unsuccessful treatment, persistent pain, signs of paraesthesia, a rapid growth rate and delayed response to therapy associated with atypical features. Complementary examinations, such as biopsy and computed tomography, can allow the early diagnosis of malignant tumours, leading to a better prognosis and thus increased survival rates and improvement in quality of life.

Impact of the blooming artefact on dental implant dimensions in 13 cone-beam computed tomography devices.

BACKGROUND: The purpose of this study was to objectively assess dimensional alteration (blooming artefact) on dental implant using 13 cone-beam computed tomography (CBCT) devices adjusted to device-specific scanning protocols and to assess whether subjective adjustment of brightness and contrast (B&C) could alter its visualization. METHODS: An anthropomorphic phantom containing a dental implant was scanned in 13 CBCT devices adjusted to three scanning protocols: medium-FOV standard resolution, small-FOV standard resolution, and small-FOV high resolution. The diameter of the implant was measured at five levels, averaged, and compared with those from a reference standard industrial CT image. B&C adjustments were performed and measurements were repeated. The intraclass correlation coefficient assessed the reliability of the measurements and general linear mixed models were applied for multiples comparisons at a 95% confidence interval. RESULTS: Implant diameter obtained from small-FOV high-resolution protocols in most CBCT devices was not significantly different when compared to that from the reference (p > 0.05). For standard protocols, significant dimensional alteration of the implant ranging from 23 to 34% (0.67 to 1.02 mm) was observed in 9 CBCT devices for small-FOV scanning (p < 0.05), and in 8 CBCT devices for medium-FOV scanning, implant dimensional alteration ranged significantly from 21 to 35% (0.62 to 1.04 mm). After B&C adjustments, dimensional alteration was reduced for several of the CBCT devices tested (p < 0.05). CONCLUSIONS: The visualization of the implant dimensional alteration differed between CBCT devices and scanning protocols with an increase in diameter ranging from 0.27 to 1.04 mm. For most CBCT devices, B&C adjustments allowed to reduce visualization of implant blooming.

Contribution of three-dimensional images in the planning of cementoblastoma resection.

Cementoblastomas are rare benign tumours that represent less than 1% of all odontogenic tumours. Complete resection is mandatory to avoid recurrence. This case report describes the contribution of three-dimensional imaging and three-dimensional printing in the pre-operative surgical planning of a large cementoblastoma that not only caused substantial compression on the inferior alveolar and mental nerves, but also caused thinning and partial erosion of the lingual and vestibular cortical bone, thus increasing the risk of pre-operative mandibular fracture.

Why do some extraction sites develop medication-related osteonecrosis of the jaw and others do not? A within-patient study assessing radiographic predictors.

PURPOSE: To compare radiographic predictors of medication-related osteonecrosis of the jaw in dental extraction sites. MATERIALS AND METHODS: Forty-one oncological patients undergoing intravenous or subcutaneous antiresorptive treatment, with a history of dental extraction visualised by panoramic imaging, were included in this retrospective study. Age-, sex- and extracted tooth-matched healthy patients who had previously undergone panoramic imaging were selected as controls (n = 57). A total of 288 extraction sites were independently evaluated by two oral and maxillofacial radiologists, who assessed eight distinct radiographic features. The radiographic features of extraction sites were noted to allow comparison between and within subjects regarding healing and osteonecrosis development. The association between radiographic findings, underlying dental disease and medication-related osteonecrosis of the jaw was also tested. The level of significance was set at 5%. RESULTS: Patients under antiresorptive treatment presented with widening of the periodontal ligament space, thickening of the lamina dura, sclerotic bone pattern, horizontal bone loss and periapical radiolucency with bone reaction (P ≤ 0.05). Development of medication-related osteonecrosis of the jaw was associated with altered bone pattern, angular bone loss, furcation involvement and unsatisfactory endodontic treatment (P ≤ 0.05). An association between medication-related osteonecrosis of the jaw and previous dental disease was also found, particularly for periapical lesions and endodontic-periodontal disease (P ≤ 0.05). CONCLUSIONS: Radiographic predictors of further development of medication-related osteonecrosis of the jaw in extraction sites include heterogeneous bone pattern, angular bone loss and furcation involvement. Extraction sites with underlying bony changes related to endodontic and endodontic-periodontal disease are more prone to development of medication-related osteonecrosis of the jaw.

Evaluation of 10 Cone-beam Computed Tomographic Devices for Endodontic Assessment of Fine Anatomic Structures.

INTRODUCTION: The purpose of this study was to classify 10 cone-beam computed tomographic (CBCT) devices using a ranking model according to the detection of fine endodontic structures. METHODS: A dedicated dentate anthropomorphic phantom was scanned 2 times using 10 CBCT devices without any metal (metal-free condition) and with an endodontically treated tooth containing a metallic post (metal condition). A reference image acquired on an industrial micro-CT scanner was used to register all CBCT images, yielding corresponding anatomic slices. Afterward, 3 experienced observers assessed all acquired CBCT images for their ability to assess a narrow canal, isthmus, and apical delta ramification using a categoric rank from 1 (best) to 10 (worst). Fleiss kappa statistics were used to calculate intra- and interobserver agreements for each CBCT device separately. Based on the observers' scores, general linear mixed models were applied to compare image quality among different CBCT devices for performing endodontic diagnostic tasks (α = .05). RESULTS: The 10 CBCT devices performed differently for the evaluated endodontic tasks (P < .05), with 3 devices performing better for endodontic feature detection. Yet, in the presence of metal, only 2 devices were able to keep a high level of endodontic feature detection. CONCLUSIONS: The evaluated endodontic tasks were CBCT device dependent, and their detection was influenced by the presence of metal.

Diagnostic accuracy of CBCT versus intraoral imaging for assessment of peri-implant bone defects.

BACKGROUND: Early detection of marginal bone loss is vital for treatment planning and prognosis of teeth and implant. This study was conducted to assess diagnostic accuracy of CBCT compared to intra-oral (IO) radiography for detection, classification, and measurement of peri-implant bone defects in an animal model. METHODS: Fifty-four mandible blocks with implants were harvested from nine male health adult beagle dogs with acquisition of IO, CBCT and micro-CT images from all samples. Peri-implant bone defects from 16 samples were diagnosed using micro-CT and classified into 3 defect categories: dehiscence (n = 5), infrabony defect (n = 3) and crater-like defect (n = 8). Following training and calibration of the observers, they asked to detect location (mesial, distal, buccal, lingual) and shape of the defect (dehiscence, horizontal defect, vertical defect, carter-like defect) utilizing both IO and CBCT images. Both observers assessed defect depth and width on IO, CBCT and micro-CT images at each side of peri-implant bone defect via CT-analyzer software. Data were analyzed using SPSS software and a p value of < 0.05 was considered as statistically significant. RESULTS: Overall, there was a high diagnostic accuracy for detection of bone defects with CBCT images (sensitivity: 100%/100%), while IO images showed a reduction in accuracy (sensitivity: 69%/63%). Similarly, diagnostic accuracy for defect classification was significantly higher for CBCT, whereas IO images were unable to correctly identify vestibular dehiscence, with incorrect assessment of half of the infrabony defects. For accuracy of measuring defect depth and width, a higher correlation was observed between CBCT and gold standard micro-CT (r = 0.91, 95% CI 0.86-0.94), whereas a lower correlation was seen for IO images (r = 0.82, 95% CI 0.67-0.91). CONCLUSIONS: The diagnostic accuracy and reliability of CBCT was found to be superior to IO imaging for the detection, classification, and measurement of peri-implant bone defects. The application of CBCT adds substantial information related to the peri-implant bone defect diagnosis and decision-making which cannot be achieved with conventional IO imaging.

Three-dimensional design of a geometric model for an ocular prosthesis in ex vivo anophthalmic socket models.

PURPOSE: Fitting a customized ocular prosthesis for anophthalmic patients entails an artisanal labour-exhausting process and is standardly based on impression moulding of the socket, which may be anatomically inaccurate. The objective of the study was to design an impression-free socket mould with three-dimensional (3D) technology. METHODS: The ex vivo anophthalmic socket models included one silicone, one fresh pig cadaver head and three fresh-frozen human cadaver heads. After intra-socket application with iodine substance, five observers obtained eighteen low-dose cone beam computed tomography (CBCT) scans and one observer one high-dose CBCT scan of each model. The observers designed non-impression 3D moulds of the socket with 3D software. For the human cadaver sockets 3D geometric models of the ocular prosthesis were rendered from the 3D mould of the socket and the mirrored cornea of the contralateral eye. RESULTS: The posterior surface of the 3D mould was highly accurate, with a mean absolute deviation of 0.28 mm, 0.53 mm, 0.37 mm and mean upper deviation of 0.53 mm, 0.86 mm, 1.17 mm, respectively, for the phantom, pig and human model. The intra- and interobserver repeatability and reproducibility of the 3D moulds and designs was good (<0.35 mm). The largest variation in the 3D geometric model was found at the junction of the 3D mould and mirrored cornea. CONCLUSION: 3D design of an impression-free geometric model for an ocular prosthesis with low-dose CBCT is highly accurate in ex vivo anophthalmic socket models. This novel method is a critical step towards the manufacturing of 3D printed ocular prostheses and requires validation in anophthalmic patients.

Cone-beam Computed Tomographic-based Assessment of Filled C-shaped Canals: Artifact Expression of Cone-beam Computed Tomography as Opposed to Micro-computed Tomography and Nano-computed Tomography.

INTRODUCTION: The present study investigated the assessment of root canal fillings in a series of cone-beam computed tomographic (CBCT) images obtained from endodontically treated mandibular molars with C-shaped canals. METHODS: Clinically comparable high (HR) and normal (NR) resolution protocols were selected in 3D Accuitomo 170 (J Morita Corporation, Kyoto, Japan), NewTom VGi evo (Cefla QR Verona, Verona, Italy), ProMax 3D Max (Pro; Planmeca, Helsinki, Finland), and Pax-i3D Green Premium (Pax; Vatech, Gyeonggi, South Korea). Micro-computed tomographic and nano-computed tomographic images were considered as the reference standard. The set of images was evaluated according to beam hardening artifact patterns (dark streaks, hypodense areas, and volume distortion). RESULTS: Regarding dark streaks, the Fleiss kappa test showed that Pax HR and NR and Pro HR images showed the highest artifact expression. Hypodense areas were detected in 100% and 99.1% of the images obtained using Pax HR and NR, respectively. Kappa tests showed highest distortion for images derived from the Pax and Pro CBCT devices. Root canal filling assessment was considered appropriate in 100% of the 3D Accuitomo 170 HR, NewTom VGi evo NR, micro-computed tomographic, and nano-computed tomographic images. CONCLUSIONS: The present study confirms the large variability in CBCT-derived artifact expression. Highlighting the increased artifact expression for particular CBCT systems, it may be concluded that for diagnosis of endodontically filled molars with C-shaped canals, the choice of CBCT unit and protocol is essential.

How image-processing parameters can influence the assessment of dental materials using micro-CT.

PURPOSE: The aim of this study was to evaluate the influence of voxel size and different post-processing algorithms on the analysis of dental materials using micro-computed tomography (micro-CT). MATERIALS AND METHODS: Root-end cavities were prepared in extracted maxillary premolars, filled with mineral trioxide aggregate (MTA), Biodentine, and Intermediate Restorative Material (IRM), and scanned using micro-CT. The volume and porosity of materials were evaluated and compared using voxel sizes of 5, 10, and 20 µm, as well as different software tools (post-processing algorithms). The CTAn or MeVisLab/Materialise 3-matic software package was used to perform volume and morphological analyses, and the CTAn or MeVisLab/Amira software was used to evaluate porosity. Data were analyzed using 1-way ANOVA and the Tukey test (P<0.05). RESULTS: Using MeVisLab/Materialise 3-matic, a consistent tendency was observed for volume to increase at larger voxel sizes. CTAn showed higher volumes for MTA and IRM at 20 µm. Using CTAn, porosity values decreased as voxel size increased, with statistically significant differences for all materials. MeVisLab/Amira showed a difference for MTA and IRM at 5 µm, and for Biodentine at 20 µm. Significant differences in volume and porosity were observed in all software packages for Biodentine across all voxel sizes. CONCLUSION: Some differences in volume and porosity were found according to voxel size, image-processing software, and the radiopacity of the material. Consistent protocols are needed for research evaluating dental materials.

A quantitative analysis of metal artifact reduction algorithm performance in volume correction with 3 CBCT devices.

OBJECTIVE: The aim of this study was to quantitatively assess the performance of metal artifact reduction (MAR) algorithms on the volume of metal cylinders, considering the influence of materials, positions, and fields of view (FOVs), by using 3 cone beam computed tomography (CBCT) devices (NewTom VGi evo, Picasso Trio, and ProMax 3-D Max). STUDY DESIGN: Nine phantoms containing cylinders of amalgam, copper-aluminum (CuAl) metal alloy, and titanium, combined in up to 3 positions, were scanned by using 2 different FOVs. MATLAB software was used to evaluate the differences between volumes before and after MAR application, and the possible interference of materials, positions, and FOVs. Wilcoxon's test and the Kruskal-Wallis test were used at a level of significance of 5%. RESULTS: In general, images containing amalgam and CuAl showed a significant difference in volume before and after MAR application. However, no significant difference after MAR was observed (P > .05) relative to positions and FOVs. MAR had an impact on the cylinder volumes only in the NewTom VGi evo and ProMax 3-D Max scanners. CONCLUSIONS: The performance of MAR algorithms in volume correction of metal objects is dependent on the materials and the CBCT unit.

Observer preference for a dedicated medical display vs a standard screen in the detection of dental radioanatomic features.

OBJECTIVE: The aim of this study was to assess observers' preference for a dentomaxillofacial dedicated medical display (MD) vs a general-purpose standard screen (SS) for in vitro and in vivo observation of normal radioanatomic features. STUDY DESIGN: The in vitro sample consisted of 2-dimensional (2-D) intraoral (n = 15), panoramic (n = 2), cephalometric (n = 2), and 3-dimensional (3-D) cone beam computed tomography (CBCT) (n = 9) data sets, acquired by utilizing commercially available skull and head-and-neck phantoms. The in vivo sample consisted of 80 radiographs (intraoral = 20; panoramic = 20; cephalometric = 20; and CBCT = 20). In vitro and in vivo data sets were both acquired by using Minray, Promax2-D, and Vistapano Ceph for 2-D images and Accuitomo, NewTom VGi evo, and Promax3-D for CBCT images. Five observers entered screen preferences when evaluating the appearance of radioanatomic structures on MD and SS. RESULTS: Both in vitro and in vivo assessments showed good interobserver and excellent intraobserver agreement. In vitro data suggested a significant preference for MD over SS for viewing radioanatomic features on panoramic and CBCT images, whereas MD was significantly preferred for in vivo images of all imaging modalities (P < .001). CONCLUSIONS: Overall, observers preferred MD over SS for both in vitro and in vivo observation of normal radioanatomic features irrespective of the imaging modality.