Assessment of accuracy and reproducibility of cephalometric identification performed by 2 artificial intelligence-driven tracing applications and human examiners

OBJECTIVE

To assess the accuracy and reproducibility of cephalometric landmark identification performed by 2 artificial intelligence (AI)-driven applications (CefBot and WebCeph) and human examiners.

STUDY DESIGN

Lateral cephalometric radiographs of 10 skulls containing 0.5 mm lead spheres directly placed at 10 cephalometric landmarks were obtained as the reference standard. Ten radiographs without spheres were obtained from the same skulls for identification of cephalometric points performed by the AI applications and 10 examiners. The x- and y-coordinate values of the cephalometric points identified by the AI applications and examiners were compared with those from the reference standard images using one-way analysis of variance and the Dunnet post-hoc test. The intraclass correlation coefficient (ICC) was used to evaluate reproducibility. Mean radial error (MRE) in identification was calculated with respect to the reference standard. Statistical significance was established at P < .05.

RESULTS

Landmark identification by CefBot and the examiners did not exhibit significant differences from the reference standard on either axis (P > .05). WebCeph produced a significant difference (P < .05) in 4 and 6 points on the x- and y-axes, respectively. Reproducibility was excellent for CefBot and the examiners (ICC ≥ 0.9943) and good for WebCeph (ICC ≥ 0.7868). MREs of CefBot and the examiners were similar.

CONCLUSION

With results similar to those of human examiners, CefBot demonstrated excellent reliability and can aid in cephalometric applications. WebCeph produced significant errors.

Do voxel size and filter application on CBCT images improve the diagnosis of condylar morphological alterations? An ex vivo study

BACKGROUND

There is no established protocol for the low doses of cone-beam computed tomography (CBCT) acquisition and filter application on the diagnosis of condylar morphological alterations.

OBJECTIVES

The objective of the study was to evaluate the influence of voxel size and filter application on the diagnosis of condylar morphological alterations in CBCT using an ex vivo model.

METHODS

CBCT scans of 36 temporomandibular joints were acquired using OP300 Maxio with voxel sizes of 0.085, 0.125 and 0.280 mm. Three radiologists evaluated the condyles in the CBCT volumes under three filter modes: no filter, '1x' sharpen filter and '2x' sharpen filter. The area under the ROC curve, sensitivity and specificity were calculated by comparing the evaluators' responses with the reference standard and compared among experimental groups using analysis of variance (ANOVA) (α = 5%).

RESULTS

The area under the ROC curve, sensitivity and specificity were not affected by voxel size and filter application (p > .05). For osteophyte and flattening, there were more true-positive responses in smaller voxel size. For erosion, the increase of true- and false-positive responses occurred with a larger voxel size. Overall, there was a tendency to decrease true positives for osteophyte and erosion and increase false positives for flattening with the '2x' sharpen filter.

CONCLUSIONS

The diagnosis of condylar morphological alterations assessed in this ex vivo analysis is not influenced by the voxel size and the application of the filters. However, attention is needed with the occurrence of false-positive diagnosis with a larger voxel size for erosion and '2x' sharpen filter for flattening.

Potential impact of metal crowns at varying distances from a carious lesion on its detection on cone-beam computed tomography scans with several protocols

Purpose

This study evaluated the impact of artifacts generated by metal crowns on the detection of proximal caries lesions in teeth at various distances using cone-beam computed tomography (CBCT). Additionally, the diagnostic impacts of tube current and metal artifact reduction (MAR) were investigated.

Materials and Methods

Thirty teeth were arranged within 10 phantoms, each containing 1 first premolar, 1 second premolar, and 1 second molar. A sound first molar (for the control group) or a tooth with a metal crown was placed. Of the 60 proximal surfaces evaluated, 15 were sound and 45 exhibited enamel caries. CBCT scans were acquired using an OP300 Maxio unit (Instrumentarium, Tuusula, Finland), while varying the tube current (4, 8, or 12.5 mA) and enabling or disabling MAR. Five observers assessed mesial and distal surfaces using a 5-point scale. Multi-way analysis of variance was employed for data comparison, with P<0.05 indicating statistical significance.

Results

The area under the curve (AUC) varied from 0.40 to 0.60 (sensitivity: 0.28-0.45, specificity: 0.44-0.80). The diagnostic accuracy was not significantly affected by the presence of a metal crown, milliamperage, or MAR (P>0.05). However, the overall AUC and specificity were significantly lower for surfaces near a crown (P<0.05).

Conclusion

CBCT-based caries detection was not influenced by the presence of a metal crown, variations in milliamperage, or MAR activation. However, the diagnostic accuracy was low and was further diminished for surfaces near a crown. Consequently, CBCT is not recommended for the detection of incipient caries lesions.

The effect of voxel and field of view size on the volumetric alteration artifact of high-density materials with 2 cone beam computed tomography devices

OBJECTIVE

We investigated the influence of voxel and field of view (FOV) sizes on expression of the volumetric alteration artifact (VAA) of 5 high-density materials in 2 cone beam computed tomography (CBCT) devices.

STUDY DESIGN

Cylinders of amalgam, cobalt-chromium, gutta-percha, titanium, and zirconium were individually positioned in a polymethyl methacrylate phantom. OP300 Maxio and ProMax 3D Classic CBCT devices were used to acquire images with varying voxel and FOV sizes, totaling 585 scans. Two evaluators segmented the high-density cylinder images to obtain the tomographic volumes. The difference between the tomographic and physical volume of each cylinder (i.e., volumetric alteration) was calculated. Statistical analysis was conducted with multiway ANOVA and the Tukey post hoc test (α = 5%). Evaluator reliability was measured with the intraclass correlation coefficient (ICC).

RESULTS

All studied parameters and nearly all interactions influenced the VAA (P < .05). The post hoc test demonstrated less volumetric alteration for the smallest voxel sizes, 61 × 78 mm FOV, and gutta-percha for OP300, and for the smallest voxel sizes, 80 × 80 mm FOV, and gutta-percha and titanium for ProMax 3D (P < .05). The ICC demonstrated perfect reliability (1.00).

CONCLUSIONS

Voxel and FOV sizes influenced VAA expression. Using smaller voxel sizes, the 61 × 78 mm FOV for OP300 and the 80 × 80 mm FOV for ProMax 3D, and materials with lower density and lower atomic number reduced VAA expression.

High-density objects in exomass affect the volume of high-density objects inside the field of view

OBJECTIVES

To evaluate the effect of the presence and the number of high-density objects in the exomass on the volume of a high-density object in cone-beam CT (CBCT).

METHODS

Cylinders of cobalt-chromium (Co-Cr), titanium (Ti), and zirconium (Zi) were inserted into a polymethylmethacrylate phantom in five different combinations of number and position: 1-no cylinder; 2-one cylinder in a posterior region; 3-one cylinder in an anterior region; 4-two cylinders in posterior regions; and 5-three cylinders in anterior and posterior regions. The phantom underwent CBCT scanning using OP300 and X800 systems, with the afore mentioned cylinders of the same composition placed in the exomass and an additional high-density cylinder placed in the centre of the field of view (FOV), corresponding to the left-anterior region. The tomographic volume of the cylinder inside the FOV was measured using semi-automatic segmentation. The volumetric alteration (VA) between the segmented and physical volumes, in percentage, was compared among the experimental groups using repeated measures ANOVA and Tukey post-hoc (α = 5%).

RESULTS

The factors material, combination, and their interaction affected the volume or both CBCT systems. In OP300, more cylinders in the exomass reduced the VA, mainly for Co-Cr. In X800, more cylinders in the exomass tended to increase the VA inside the FOV, except for Zi.

CONCLUSIONS

In general, the presence of high-density objects in the exomass influences the VA of the object inside the FOV, although this oscillates according to object composition, number and position in the exomass, and CBCT system.

Influence of an adjacent zirconium implant, tube current, and metal artifact reduction algorithm on horizontal root fracture diagnosis in cone beam computed tomography

OBJECTIVE

We evaluated the influence of an adjacent zirconium implant, tube current (mA), and a metal artifact reduction algorithm (MARA) on horizontal root fracture (HRF) diagnosis in cone beam computed tomography (CBCT).

STUDY DESIGN

Nineteen teeth (9 with HRF, 10 without) were individually placed in a human maxilla. Scan volumes were acquired without and with a zirconium implant adjacent to the tooth at settings of 4, 8, and 10 mA, with MARA disabled and enabled, using a 5×5 cm field of view, 0.085-mm voxel size, and 90 kV. Four maxillofacial radiologists individually assessed the scans. Diagnostic metrics were compared by multiway analysis of variance (α=5%). Inter- and intraexaminer agreements for HRF diagnosis were evaluated with the weighted kappa test.

RESULTS

Area under the receiver operating characteristic curve (AUC), sensitivity, and specificity were significantly lower in the presence of the implant (P≤.005). AUC values were higher in scans obtained with 8 and 10 mA compared with 4 mA (P=0.010), but 10 mA without MARA was better with the implant present. MARA did not significantly influence outcomes (P≥0.240). Inter- and intraexaminer agreements ranged from moderate to almost perfect.

CONCLUSIONS

The presence of the zirconium implant impairs HRF detection. Settings of 8 or 10 mA improve HRF detection regardless MARA condition without the implant. With an adjacent implant, 10 mA without MARA is recommended to improve diagnostic performance.

Influence of the metal post material, tooth location in the dental arch, and metal artifact reduction tool on vertical root fracture diagnosis in cone beam CT

This study aimed to evaluate the influence of the metal post composition, tooth location in the dental arch, and metal artifact reduction (MAR) on vertical root fracture (VRF) diagnosis in cone beam computed tomography (CBCT). Twenty-two unirradicular premolars (12 sound and 10 fractured) and two alveolar sockets of a mandible (anterior and posterior regions) composed the sample. CBCT scans of each tooth with a metal post placed into the root canal-silver-palladium (Ag-Pd), cobalt-chromium (Co-Cr), or nickel-chromium (Ni-Cr)-were individually acquired for each mandibular region, and two conditions of MAR, using a OP300 device (Instrumentarium, Finland). Images were assessed by five evaluators independently for VRF detection. Diagnostic values were calculated and compared among all groups using multi-way ANOVA with Tukey post hoc test to investigate the effect of post material, anatomical region, and MAR on VRF diagnosis (α = 0.05). Values of area under the receiver operating curve and specificity were not influenced by the studied factors (p > 0.05). Sensitivity was influenced by the MAR in both mandibular regions (p < 0.05). In the anterior region, sensitivity values increased when the MAR was enabled, regardless of the metal post material (p < 0.05). Similar behavior was noticed in the posterior region for Ni-Cr (p < 0.05) but not for Ag-Pd and Co-Cr posts (p > 0.05). The MAR improved the sensitivity in VRF diagnosis for all tested metal posts in the mandibular anterior region and for the Ni-Cr post in the mandibular posterior region. Therefore, for images obtained in the OP300 CBCT device, activation of the MAR is suggested in these cases.

Mapping artifacts generated in a tooth adjacent to titanium and zirconia implants located in the endomass and exomass in cone beam computed tomography: an ex vivo study

OBJECTIVE

We evaluated artifact expression in a root adjacent to a dental implant located in the endomass or exomass in cone beam computed tomography (CBCT).

STUDY DESIGN

We placed a single titanium or zirconia implant adjacent to a premolar root in a dried human mandible and acquired CBCT scans using an OP300 Maxio and a Picasso Trio 3D unit exposing a 5x5cm field of view with the implant in the endomass or exomass (implant groups) or without an implant (control group). We measured the mean gray values (MGVs) for 8 lines of interest (LOIs) around the root canal of the premolar and compared the MGVs by analysis of variance, with significance established at P < 0.05.

RESULTS

For the OP300 Maxio scans, the MGVs of both implant groups in the endomass were lower than the MGVs of the control group. In the exomass, the titanium group had MGVs similar to the control group, but the zirconia group produced significantly lower MGVs than control and titanium groups (P <.0001), indicating the presence of hypodense artifacts. For the Picasso Trio 3D scans, the MGVs of both implant groups in the endomass were similar to the MGVs of the control group. In the exomass, the zirconia group generated lower MGVs than control and titanium groups (P <.0001), indicating hypodense artifacts.

CONCLUSIONS

When performing CBCT examination, titanium implants produce less artifact expression in the exomass, and zirconia implants have less artifact expression in the endomass.

Metaverse and oral and maxillofacial radiology: Where do they meet?

Since previous literatureregarding the application of the metaverse in educationis scarce, the present letter aimed to highlight possible applications, as a complementary tool for the classroom, in the oral and maxillofacial radiology academic experience.Thepotential risksof the metaverse are also discussed. The metaverse and its possible applications, especially related to enhanced teaching and learning, will become a hot topic in the near future, and therefore, there will be a challenging learning curve before the educator makes the most of these innovative educational tools empowered by deeply interactive virtual reality technology.

Disinfection of intraoral photostimulable phosphor plates with 70% ethyl alcohol and 70% isopropyl alcohol alters image contrast and produces image artifacts

OBJECTIVE

This study evaluated changes in image quality and the presence and size of artifacts on radiographs obtained with photostimulable phosphor (PSP) plates after disinfection with 70% ethyl alcohol and 70% isopropyl alcohol.

STUDY DESIGN

Eight PSP receptors (4 Express and 4 VistaScan) were used for the investigation. Two Express and 2 VistaScan receptors were disinfected with 70% ethyl alcohol, and 2 Express and 2 VistaScan receptors were disinfected with 70% isopropyl alcohol. Before disinfection and after every 5 disinfections, 2 radiographs of an aluminum stepwedge and 2 radiographs of an acrylic block were acquired using each receptor. The gray values of the radiographs were analyzed regarding contrast, density, uniformity, and noise. Four oral radiologists evaluated the images for the presence of artifacts, and 2 measured the artifacts.

RESULTS

Differences in image contrast were significantly larger with isopropyl alcohol (P < .0001). Artifact size was significantly greater with the VistaScan system when isopropyl alcohol was used as the disinfectant (P < .0001). The correlation between the number of disinfections and artifact size was moderately positive with the Express system (P < .05) and strongly positive with the VistaScan system (P < .05) with both disinfectants.

CONCLUSIONS

Small artifacts restricted to the edges of the image were observed with disinfection using both types of alcohol, and a positive correlation was found between artifact size and the number of disinfections. However, artifacts appeared earlier and of greater size with the VistaScan system when disinfected with 70% isopropyl alcohol. Thus, we recommend using 70% ethyl alcohol to disinfect PSP receptors, with attention placed on its action and evaporation times.

Does cone-beam CT convex triangular field of view influence the image shape distortion of high-density materials?

OBJECTIVES

To assess the distortion of high-density materials using two CBCT devices presenting convex triangular and cylindrical fields of view (FOVs).

METHODS AND MATERIALS

Four high-density cylinders were individually placed in a polymethylmethacrylate phantom. 192 CBCT scans were acquired using the convex triangular and cylindrical FOVs of Veraviewepocs® R100 (R100) and Veraview® X800 (X800) devices. Using HorosTM's software, two oral radiologists determined the cylinders' horizontal and vertical dimensional alterations. Nine oral radiologists subjectively identified each cylinder's axial shape distortion. Statistical analysis comprised Multiway ANOVA (α = 5%), and the Kruskal-Wallis test.

RESULTS

The distortion in the axial plane was greater in the convex triangular FOVs for both devices in almost all the materials (p < 0.05). The evaluators subjectively identified a shape distortion in both FOVs for R100 device (p < 0.001), while no distortion was identified for X800 device (p = 0.620). A vertical magnification of all materials was observed in both FOVs for both devices (p < 0.05). No differences among vertical regions (p = 0.988) nor FOVs (p = 0.544) were found for the R100 device, while all materials showed higher magnification in all regions in the cylindrical FOV (p < 0.001) of the X800 device.

CONCLUSIONS

The convex triangular FOV influenced the axial distortion of the high-density materials in both devices. A vertical magnification was observed in both FOVs of both devices, but it was greater in the cylindrical FOV of the X800 device.

Radiographic evaluation of mandibular third molars: an ex vivo comparative study between multilayer and conventional panoramic radiography

OBJECTIVES

To compare the multilayer panoramic radiography (MPAN) and conventional panoramic radiography (CPAN) in the evaluation of mandibular third molars using cone-beam computed tomography (CBCT) as a reference.

METHODS

CPAN, MPAN, and CBCT scans from 33 dry human mandibles were acquired using the OP300 Maxio unit, totalizing 56 mandibular third molars to be evaluated. Three examiners evaluated each third molar according to their position, depth of impaction in the mandibular ramus, proximity between the dental root apexes and the mandibular canal, and the presence of radiographic signs of proximity to the mandibular canal. In addition, when there was a distance between the root apexes and the mandibular canal, it was measured. As a reference, these same parameters were assessed in the CBCT scans by a fourth examiner. For the statistical analysis, the weighted Kappa, Bland Altman, and Wilcoxon tests were performed (α = 0.05).

RESULTS

The agreement between the assessments performed in the panoramic modalities with the CBCT ranged from 66.1% to 100.0% for the categorical variables. Overall, the agreement values of CPAN and MPAN with CBCT were similar. The distances between the dental root apex and the mandibular canal for both CPAN and MPAN were significantly underestimated compared to CBCT (p < 0.05). The intra- and interexaminer agreements of the examiners ranged from poor to almost perfect; in general, the agreements were higher in the evaluation performed in the MPAN than in the CPAN.

CONCLUSIONS

The MPAN performs similarly to CPAN for evaluating mandibular third molars and their proximity relationship to the mandibular canal.

CLINICAL RELEVANCE

Preoperative evaluation of lower mandibular third molars is usually performed using CPAN. Recently, a new tool, MPAN, was developed, which has not yet been tested for the evaluation of mandibular third molars and showed similar performance to CPAN in the present study. Future studies using MPAN are encouraged to evaluate other diagnostic tasks.

Does the shape of the field-of-view influence the magnitude of artefacts from high-density materials in cone-beam computed tomography?

OBJECTIVE

To compare cylindrical and convex triangular field-of-views (FOVs) concerning the magnitude of artefacts from high-density materials in cone-beam CT (CBCT).

METHODS AND MATERIALS

Cylinders of amalgam, chromium-cobalt, titanium, and zirconia were individually placed in the anterior and posterior regions of a polymethylmethacrylate phantom and scanned using cylindrical and convex triangular FOVs of the Veraview X800 CBCT device. Using the Image J software, 15 square regions of interest (ROIs) were placed in the axial reconstruction around the middle level of the cylinder and at distances of 0.5, 1.0, and 1.5 cm from the centre of the cylinder. Mean grey value and standard deviation of each ROI were averaged for each distance and subtracted from the values of a control ROI to calculate the magnitude of the artefacts by the grey value mean difference (GVMD) and grey value standard deviation (GVSD). Multiway analysis of variance with Tukey post-hoc test with a significance level of 5% evaluated the effect of the shape of the FOV, position inside the FOV, high-density material, and the distance of the artefact from the material.

RESULTS

The convex triangular FOV increased the GVSD for all materials in the anterior and posterior regions at 0.5 cm compared to the cylindrical FOV (p < 0.0001). The convex triangular FOV showed greater GVMD for chromium-cobalt and zirconium in the anterior region and all materials in the posterior region at all distances (p < 0.0001).

CONCLUSION

The FOV shape influences the magnitude of artefacts from high-density materials. The convex triangular FOV showed greater artefact magnitude with variability among the high-density materials, region in the FOV, and distance from the material.

Does low bone mineral density have an association with head and neck soft tissue calcifications?

OBJECTIVES

To evaluate whether low bone mineral density (BMD) has an association with the presence of head and neck soft tissue calcifications (STC), aging, and impaired mandibular canal cortices visibility.

MATERIALS AND METHODS

Panoramic radiographs of 1000 women aged between 50 and 75 years old were evaluated by two examiners to classify BMD using mandibular cortical index (C1- normal, C2-moderately eroded and C3-severely eroded), the presence of STC, and also the mandibular canal cortices visibility at the ramus region. Chi-square test evaluated the association between the variables (α = 5%).

RESULTS

There was no association between bone loss and the presence of head and neck soft tissue calcifications, except for calcified thyroid cartilage, which was less visualized at C3 group than others (p < 0.05). Women aged 61 to 70 years old presented higher bone loss than those between 50 and 60 (p < 0.05). The mandibular canal was more poorly visualized at C3 group than C1 and C2 (p < 0.05).

CONCLUSIONS

In general, no association between BMD and the presence of STC was found. However, greater bone loss had a positive correlation with aging and impaired mandibular canal cortices visibility.

CLINICAL RELEVANCE

No relationship between bone mineral density and the existence of soft tissue calcifications was found. Nevertheless, increased bone loss was positively associated with aging and a reduced mandibular canal cortices visibility. This finding highlights the clinical importance of considering bone density factors when planning treatment strategies for patients with related disorders.

Can maxillary molar dimensions predict the presence of the second mesiobuccal canal?

OBJECTIVE

To evaluate the potential of maxillary molar dimensions as predictors of the presence of the second mesiobuccal (MB2) canal.

METHODS

Micro-computed tomography scans were obtained from 47 maxillary molars, out of which 26 had the MB2 canal. The distance between root canals, extension of the canals, and thickness of surrounding dentin were obtained from axial images at the furcation level, 3 mm from the apex, and 5 mm from the apex. The association between the measurements and the presence of the MB2 canal was assessed using multiple logistic regression and odds ratio.

RESULTS

At the furcation level, the bucco-palatal extension of the MB1 canal significantly decreased the chance of the presence of the MB2 canal. Regarding the thickness of surrounding dentin measurements, the mesial and distal aspects of the MB1 canal at 3 mm from the apex were statistically significant to decrease and increase the chance of presence of the MB2 canal, respectively. Regarding the extension of the canals, only buccal-palatal extension seems to decrease the chance of the presence of the MB2 canal.

CONCLUSION

The presence of the MB2 canal in the mesiobuccal root of maxillary molars is associated with the bucco-palatal extension and surrounding dentin thickness of the first mesiobuccal canal, and seems to be unrelated to the dimensions of the distobuccal and palatal roots.

DICOM file format has better radiographic image quality than other file formats: an objective study

This study aimed to assess the influence of the file format on the image quality parameters (image noise, brightness, and uniformity) of periapical radiographs acquired with different digital systems. Radiographic images of an acrylic phantom were acquired with two digital systems - Digora Toto and Express, and exported into five different file formats - TIFF, BMP, DICOM, PNG, and JPEG. Image noise, image brightness (mean of gray values), and image uniformity (standard deviation of gray values) were evaluated in all images. A two-way analysis of variance with Tukey's test as a post-hoc test was used to compare the results, considering the file formats and radiographic systems as the studied factors. A significance level of 5% was adopted for all analyses. The DICOM image file format presented lower image noise, higher brightness (higher mean gray values), and greater image uniformity (p<0.001) than the other file formats, which did not differ from each other for both digital radiography systems (p>0.05). The Express system revealed lower image noise and greater image uniformity than the Digora Toto system regardless of the image file format (p<0.001). Moreover, the Express showed higher brightness than the Digora Toto for all image file formats (p<0.001), except for the DICOM image file format, which did not significantly differ between the digital radiography systems tested (p>0.05). The DICOM image file format showed lower image noise, higher brightness, and greater image uniformity than the other file formats (TIFF, BMP, PNG, and JPEG) in both digital radiography systems tested.

Tridimensional assessment of the mandibular angle in patients with different skeletal patterns by cone-beam computed tomography scans: a retrospective study

BACKGROUND

Since the muscles of chewing are involved in the region of the mandibular angle, important structures in surgical and orthodontic procedures, to study its morphological aspects and the possible influence of different patterns of skeletal development would be of interest. Thus, this study aimed to assess the influence of patient characteristics - such as sex, skeletal malocclusion (Class I, Class II, and Class III) and facial type (brachycephalic, mesocephalic, and dolichocephalic) - on the width, height, thickness, and volume of the mandibular angle, using cone-beam computed tomography (CBCT) scans.

METHODS

CBCT scans were assessed - 144 men and 154 women, total of 298 - and classified according to skeletal patterns (skeletal malocclusions and facial types). Width, height, and thickness of the mandibular angle were measured using OnDemand 3D software. The volumetric measures of the mandibular angle were obtained using the ITK-SNAP software. Analysis of Variance (multiway ANOVA) with Tukey's post-hoc test compared the data, with a 5% significance level.

RESULTS

Among the factors studied, sex significantly influenced all the analyzed variables (height, width, thickness, and volume of the mandibular angle) (p < 0.05); in general, male individuals presented higher values than females. In some cases, the skeletal malocclusion and facial type factors influenced only the width and height variables (p < 0.05); in general, the Class III and dolichocephalic individuals presented higher values in relation to the other types of skeletal malocclusions and facial types.

CONCLUSIONS

Variations in the craniofacial growth pattern, considering the different skeletal malocclusions and facial types, had some influence in the width and height dimensions of the mandibular angle. Furthermore, sex influenced all the studied variables.

Influence of CBCT parameters on image quality and the diagnosis of vertical root fractures in teeth with metallic posts: an ex vivo study

Objectives

The aim of this study was to evaluate the influence of peak kilovoltage (kVp) and a metal artifact reduction (MAR) tool on image quality and the diagnosis of vertical root fracture (VRF) in cone-beam computed tomography (CBCT).

Materials and Methods

Twenty single-rooted human teeth filled with an intracanal metal post were divided into 2 groups: control (n = 10) and VRF (n = 10). Each tooth was placed into the socket of a dry mandible, and CBCT scans were acquired using a Picasso Trio varying the kVp (70, 80, 90, or 99), and the use of MAR (with or without). The examinations were assessed by 5 examiners for the diagnosis of VRF using a 5-point scale. A subjective evaluation of the expression of artifacts was done by comparing random axial images of the studied protocols. The results of the diagnoses were analyzed using 2-way analysis of variance and the Tukey post hoc test, the subjective evaluations were compared using the Friedman test, and intra-examiner reproducibility was evaluated using the weighted kappa test (α = 5%).

Results

The kVp and MAR did not influence the diagnosis of VRF (p > 0.05). According to the subjective classification, the 99 kVp protocol with MAR demonstrated the least expression of artifacts, while the 70 kVp protocol without MAR led to the most artifacts.

Conclusions

Protocols with higher kVp combined with MAR improved the image quality of CBCT examinations. However, those factors did not lead to an improvement in the diagnosis of VRF.

Translucency and Radiopacity of Dental Resin Composites - Is There a Direct Relation?

OBJECTIVES

The purpose of this study was to correlate the translucency degree of varying resin composites with their radiopacity.

METHODS AND MATERIALS

Twenty-four resin composites (conventional or bulk-fill) of various shades and opacities were selected from the following manufacturers: 3M ESPE (nanofilled), Ivoclar (nanohybrid), and FGM (microhybrid). Resin composite samples (n=5) were prepared (5-mm diameter × 1.5-mm thickness) for comparison using prepared samples of human dentin and enamel as controls. The translucency of each sample was measured using the translucent parameter (TP) method with a digital spectrophotometer (Vita Easyshade) and CIEL*a*b* color system over white and black backgrounds. The samples were also x-rayed using a photostimulable phosphor plate system for measurement of their radiopacity (in mmAl). All data were analyzed using one-way ANOVA and Student-Newman-Keuls (α=0.05); data for TP and radiopacity were correlated using the Spearman correlation test.

RESULTS

Overall, the translucent shades and bulk-fill resin composites showed greater translucency than the other resins. While "body" and "enamel" shades demonstrated intermediate translucency to dentin and enamel, the "dentin" shades were more standardized, showing similar translucency to human dentin. All tested resin composites showed similar or greater radiopacity to human enamel, except the Empress Direct (Ivoclar) resin with Trans Opal shade, which was not radiopaque. Dentin and enamel showed radiopacity similar to 1 and 2 mmAl (millimeters of aluminum), respectively.

CONCLUSIONS

The resin composites investigated in this study differed regarding their translucency degree and radiopacity level, without any positive relationship between the two properties.

Revisiting dynamic range and image enhancement ability of contemporary digital radiographic systems-part 2: a subjective assessment

OBJECTIVE

To assess the subjective image quality of original and manually enhanced radiographs acquired at different X-ray exposure times and using different digital systems.

METHODS

A total of 500 radiographs obtained under 10 exposure times, 5 digital systems, and 2 enhancement conditions were assessed by 5 observers, who were asked to categorize each radiograph into acceptable or unacceptable. A radiograph was considered to be acceptable when at least four out of five observers found it acceptable. Descriptive analysis was used to summarize the outcomes and compare the subjective image quality of original and manually enhanced digital radiographs among different X-ray exposure times and digital systems.

RESULTS

Express had six exposure times producing acceptable original images within a range from 0.063 to 0.4 s, followed by Digora Toto, which had five within a range from 0.063 to 0.32 s, Digora Optime, which had four within a range from 0.063 to 0.2 s,and SnapShot and VistaScan, which had 2 (0.2 and 0.32 s) and 1 (0.63 s), respectively. Image enhancement turned unacceptable images into acceptable ones in four digital systems: SnapShot at three exposure times, Digora Toto at two exposure times, Express at one exposure time, and VistaScan at four exposure times.

CONCLUSION

Image enhancement based on brightness and/or contrast adjustments may be necessary to reveal the useful dynamic range of some digital radiographic systems and PSP-based systems may not necessarily have a wider range than sensor-based systems.

Convolutional neural network-based automated maxillary alveolar bone segmentation on cone-beam computed tomography images

OBJECTIVES

To develop and assess the performance of a novel artificial intelligence (AI)-driven convolutional neural network (CNN)-based tool for automated three-dimensional (3D) maxillary alveolar bone segmentation on cone-beam computed tomography (CBCT) images.

MATERIALS AND METHODS

A total of 141 CBCT scans were collected for performing training (n = 99), validation (n = 12), and testing (n = 30) of the CNN model for automated segmentation of the maxillary alveolar bone and its crestal contour. Following automated segmentation, the 3D models with under- or overestimated segmentations were refined by an expert for generating a refined-AI (R-AI) segmentation. The overall performance of CNN model was assessed. Also, 30% of the testing sample was randomly selected and manually segmented to compare the accuracy of AI and manual segmentation. Additionally, the time required to generate a 3D model was recorded in seconds (s).

RESULTS

The accuracy metrics of automated segmentation showed an excellent range of values for all accuracy metrics. However, the manual method (95% HD: 0.20 ± 0.05 mm; IoU: 95% ± 3.0; DSC: 97% ± 2.0) showed slightly better performance than the AI segmentation (95% HD: 0.27 ± 0.03 mm; IoU: 92% ± 1.0; DSC: 96% ± 1.0). There was a statistically significant difference of the time-consumed among the segmentation methods (p < .001). The AI-driven segmentation (51.5 ± 10.9 s) was 116 times faster than the manual segmentation (5973.3 ± 623.6 s). The R-AI method showed intermediate time-consumed (1666.7 ± 588.5 s).

CONCLUSION

Although the manual segmentation showed slightly better performance, the novel CNN-based tool also provided a highly accurate segmentation of the maxillary alveolar bone and its crestal contour consuming 116 times less than the manual approach.

Morphological and topographic evaluation of the mandibular canal and its relationship with the facial profile, skeletal class, and sex

PURPOSE

The aim of this study was to evaluate the morphology and topography of the mandibular canal in patients with different facial profiles, skeletal classes, and sexes.

METHODS

Cone-beam computed tomography volumes of 103 patients were classified according to facial profile and skeletal class. Two examiners classified the mandibular canal into a linear, spoon-shaped, elliptical arc, or turning curvature and measured four related linear distances. The most frequent mandibular canal curvature was identified and multi-way ANOVA with Tukey's test compared the linear measurements between facial types, skeletal class, and sexes (α = 0.05). Kappa and intraclass correlation coefficients were used to assess the reproducibility of qualitative and quantitative variables, respectively.

RESULTS

The examiners showed excellent reproducibility. The four curvatures of the mandibular canal were found, but the spoon-shaped and elliptical arch were the most frequent. No significant differences were observed for most of the linear measurements between the different facial profiles, skeletal classes, and sexes (p > 0.05).

CONCLUSION

Spoon-shaped and elliptical arch are the most frequent curvatures of the mandibular canal; furthermore, its morphology and topography seem to be little influenced by the facial profile, skeletal class, and sex.

Could the radiographic image quality be affected by the excessive use of the photostimulable phosphor plate?

The study aimed to assess the influence of excessive use of a photostimulable phosphor plate (PSP) on the density, image noise, and contrast of radiographs. For that, radiographs of an acrylic block were acquired with a PSP of the Express intraoral system to assess the density and image noise. Initially, five images were obtained and exported (first group). After 400 exposures to X-rays and scannings of PSP, other five images were obtained and exported (second group). The same procedure was done after 800 (third group), 1200 (fourth group), 1600 (fifth group), and 2000 acquisitions (sixth group), resulting in 30 images to be evaluated. The mean and standard deviation of the gray values were calculated for the images using the ImageJ software. For contrast analysis, radiographs of an aluminum step-wedge were acquired with a new PSP following the same acquisition intervals. The percentage of contrast variation was calculated. Another two unused PSP receptors were employed to evaluate the method's reproducibility. The comparison of the results among the acquisition groups was performed with one-way Analysis of Variance (α=0.05). Intraclass Correlation Coefficient (ICC) assessed the reproducibility of the receptors. Image noise did not differ among the groups (p>0.05). There was a slight increase in density after 400 acquisitions and a slight difference in contrast for all acquisition groups without a pattern of increase or decrease (p<0.05). ICC showed excellent reliability for the methods. Therefore, excessive PSP use slightly affected the radiograph's density and contrast.

A novel method of objectively detecting tooth ankylosis using cone-beam computed tomography: A laboratory study

Purpose

The aim of this study was to objectively detect simulated tooth ankylosis using a novel method involving cone-beam computed tomography (CBCT).

Materials and Methods

Tooth ankylosis was simulated in single-rooted human permanent teeth, and CBCT scans were acquired at different current levels (5, 6.3, and 8 mA) and voxel sizes (0.08, 0.125, and 0.2). In axial reconstructions, a line of interest was perpendicularly placed over the periodontal ligament space of 21 ankylosed and 21 non-ankylosed regions, and the CBCT grey values of all voxels along the line of interest were plotted against their corresponding X-coordinates through a line graph to generate a profile. The image contrast was increased by 30% and 60% and the profile assessment was repeated. The internal area of the resulting parabolas was obtained from all images and compared between ankylosed and non-ankylosed regions under different contrast enhancement conditions, voxel sizes, and mA levels using multi-way analysis of variance with the Tukey post hoc test (α=0.05).

Results

The internal area of the parabolas of all non-ankylosed regions was significantly higher than that of the ankylosed regions (P<0.05). Contrast enhancement led to a significantly greater internal area of the parabolas of non-ankylosed regions (P<0.05). Overall, voxel size and mA did not significantly influence the internal area of the parabolas (P>0.05).

Conclusion

The proposed novel method revealed a relevant degree of applicability in the detection of simulated tooth ankylosis; increased image contrast led to greater detectability.

Middle mesial root canals in mandibular molars: prevalence and correlation to anatomical aspects based on CBCT imaging

OBJECTIVES

To determine the prevalence of middle mesial root canal (MMC) in a Brazilian subpopulation, verify whether its presence is related to anatomical characteristics of the tooth, and propose a classification using cone-beam computed tomography (CBCT).

METHODS

CBCT scans of 284 patients were evaluated by 2 radiologists to determine the presence of the MMC in mandibular first and second molars. Subsequently, the mesiodistal and buccolingual measurements of the mesial roots were obtained; the measurements between the root canals, and from MMC to the mesiobuccal canal and to the mesiolingual canal were also obtained. The MMC was classified according to its relationship with mesiobuccal and mesiolingual canals. The data were analyzed using χ2 and Fisher's exact test, multiple logistic regression analysis, Student's t-test, κ and intraclass correlation coefficient (p < 0.05).

RESULTS

The intraexaminer agreements for the presence of the MMC and the measurements were considered almost perfect (0.953 and 0.999, respectively). Of 216 mandibular first molars, 11.1% had the MMC, and of 228 mandibular second molars, only 1.75% had the MMC. The presence was significant higher in the mandibular first molar (p < 0.0001). The buccolingual measurement and the measurement between mesiobuccal and mesiolingual canals were higher in teeth with MMC (p = 0.024 and p = 0.005, respectively). It was possible to classify the configuration of MCC into four types: independent (60.7%), confluent (14.3%), mesiolingual confluent (14.3%), and mesiobuccal confluent (10.7%).

CONCLUSIONS

The prevalence of MMC is more pronounced in mandibular first molars and anatomical measurements, such as greater measurement between mesiobuccal and mesiolingual canals, may alert clinicians to its presence. It was found four types of configurations of MMC.

Influence of extensive use of a photostimulable phosphor receptor on the diagnosis of proximal carious lesions: An in vitro study

OBJECTIVE

The aim of this study was to evaluate the influence of the extensive use of a photostimulable phosphor (PSP) receptor on the diagnosis of proximal carious lesions.

STUDY DESIGN

Forty posterior teeth were paired and mounted in 20 phantoms. Using a PSP receptor of the Express intraoral system, 1 radiograph of each phantom was acquired, totaling 20 radiographs (group 1). After 400 acquisitions, another radiograph of each phantom was obtained, totaling 20 new radiographs (group 2). This procedure was also done after 800 (group 3), 1,200 (group 4), and 1,600 (group 5) acquisitions, resulting in 100 radiographs. Another 40 radiographs (20 phantoms × 2 groups) were obtained with a second PSP sensor to evaluate the diagnostic replicability of the receptors. All 140 radiographs were assessed independently by 5 examiners for the presence of proximal caries. Area under the receiver operating characteristic curve, sensitivity, and specificity were calculated and compared among the groups by analysis of variance. The Student t test evaluated the diagnostic replicability of the receptors. The significance level was set at 5% (P < .05).

RESULTS

The diagnostic outcomes for proximal caries did not differ among the groups (P ≥ .37). The diagnostic values did not differ among the radiographs acquired with the 2 PSP receptors (P ≥ .75).

CONCLUSIONS

The diagnosis of proximal carious lesions was not affected by extensive use of the PSP receptor.

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, anteriorized and posteriorized) 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 inter-examiner reliability and comparisons between dependent variables analyzed 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<0.05).

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.

Influence of artefacts generated by titanium and zirconium implants in the study of trabecular bone architecture in cone-beam CT images

OBJECTIVES

To evaluate the influence of artefacts generated by titanium and zirconium implants on trabecular bone architecture assessment through cone-beam CT (CBCT). The influence of kilovoltage (kVp) and metal artefact reduction (MAR) in such analysis was also assessed.

METHODS

CBCT scans were obtained with Picasso Trio with or without a titanium or zirconium implants in a posterior region of a mandible using 70, 80 or 90 kVp, with or without MAR. The other acquisition settings were constant: field of view 8 × 5 cm, voxel size 0.2 mm, 5 mA, 24 s and 720 frames. Two volumes of interest (VOIs) were determined comprising trabecular bone mesial and distal to the implant area. The following morphometric parameters were measured: connectivity density (Conn. Dn.), fractal dimension (FD), bone volume fraction (BV/TV), bone surface density (BS/TV), trabecular thickness (Tb. Th.), and trabecular spacing (Tb. Sp.), and compared by multiway ANOVA (α = 0.05).

RESULTS

For Conn. Dn. and FD, with MAR, the zirconium group showed values significantly lower than the other groups (p < 0.05). For BV/TV, BS/TV, Tb. Th. and Tb. Sp., the zirconium group showed the highest values, regardless of MAR condition (p < 0.05). MAR increased BS/TV and Tb. Th. values, and decreased FD values for zirconium group. In general, the kVp level did not influence trabecular morphometric parameters.

CONCLUSION

The assessment of the trabecular bone architecture was mainly influenced by the expression of the artefacts generated by zirconium implants. MAR decreased the FD and increased the BS/TV and Tb.Th. values regardless of the kVp level.

Influence of sharpening filters on the detection of root fractures using low-dose cone-beam computed tomography

OBJECTIVES

To evaluate the influence of sharpening filters in the detection of root fractures using low-dose cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

Eighty-four CBCT volumes acquired at three mA levels of 28 teeth inserted in the dental socket of dry human skull were selected from a previous study. The teeth were divided into four groups according to the presence and absence of root fracture and endodontic filling. Five radiologists evaluated all CBCT volumes for the presence of root fracture with and without the application of "Sharpen 1x" and "Sharpen 2x" filters in OnDemand3D software. Area under the ROC curve (AUC), sensitivity, specificity, and inter- and intra-observer concordance were calculated and compared (α = 0.05).

RESULTS

Sharpening filters did not lead to significant differences in AUC, sensitivity, and specificity at the three mA levels tested (p > 0.05), regardless of the presence of endodontic filling (p > 0.05). However, the significant reduction of AUC observed in CBCT volumes at 4 mA without filter (p < 0.05) ceased to exist after the application of filters (p > 0.05). Sensitivity and specificity ranged from low and moderate.

CONCLUSIONS

The use of sharpening filters can be recommended in CBCT volumes at 4 mA for root fracture detection for leading to the same performance as those at 6.3 and 10 mA. The presence of endodontic filling material did not influence the action of filters in the diagnosis of root fracture.

CLINICAL RELEVANCE

Sharpening filters seem to contribute to the diagnosis of root fracture in CBCT volumes acquired with reduced radiation dose.

Reproducibility and diagnostic value of a new wedge-guided bitewing image receptor-holding device

OBJECTIVE

To assess the reproducibility of a wedge-guided bitewing image receptor-holding device (IRHD-WG) compared to a commercially available bitewing image receptor-holding device (IRHD-XCP).

METHODS AND MATERIALS

Ten operators randomly acquired bitewing radiographs of four posterior regions (Premolar, Molar 1, Molar 2, Molar 3) distributed in two dry bone skulls and mandibles using 2 IRHDs (IRHD-WG and IRHD-XCP). The radiographs corresponding to the same region and IRHD but acquired by different operators were paired for reproducibility comparison. A total of 360 pairs of radiographs were randomized for analysis. Objective analysis consisted of extracting the pixel values from each radiograph and comparing the values between each pair by intraclass correlation coefficient. For subjective analysis, the IRHDs images were digitally removed. Five oral radiologists blinded for the study conditions classified the radiograph pairs according to their similarity and diagnostic value. The answers' relative frequencies were compared by the chi-square test (α = 0.05).

RESULTS

The IRHD-WG presented a higher reproducibility (Mean = 0.850; SD = 0.144) than the IRHD-XCP (Mean = 0.615; SD = 0.287) in the objective analysis. Radiographs acquired with the IRHD-WG were more similar than those acquired with the IRHD-XCP (p < 0.001). The diagnostic value of bitewing radiographs acquired with the IRHD-WG was considered superior to those acquired with the IRHD-XCP (p < 0.001).

CONCLUSION

For the objective and subjective analyses of reproducibility, the IRHD-WG performed better than the commercial IRHD-XCP.

The metal post material influences the performance of artefact reduction algorithms in CBCT images

Abstract This study aimed to assess the effect of the MAR tool on the expression of artefacts in different regions of a tooth restored with different types of metal posts. Alveolar sockets (anterior, and posterior region) of a mandible and an unirradicular tooth were used. Cone beam computed tomography scans of the tooth without a metal post, and with cobalt-chromium (Co-Cr), nickel-chromium (Ni-Cr), or silver-palladium (Ag-Pd) were individually obtained, with 2 MAR conditions: disabled, and enabled. In an axial reconstruction, lines of interest (LOIs) were set around the canal: 4 in oblique (mesiobuccal, distobuccal, mesiolingual, distolingual) directions, and 4 in orthogonal (mesial, distal, buccal, lingual) directions. Beam-hardening artefacts expression was determined by calculating the difference in the mean of gray values (DMGV) between the experimental and control groups for each LOI. There was no significant difference in the DMGV values between “without MAR” and “with MAR” for any LOI, in neither anterior nor posterior mandible (p>0.05), for the Ni-Cr and Co-Cr groups. For the Ag-Pd, significant differences in the DMGV values were observed between “without MAR” and “with MAR” for most LOIs (p<0.05), mainly in oblique directions in the anterior region, and mesio-distal direction in the posterior region. MAR acted mostly in hypodense artefacts (negative DMGV). The effectiveness of the MAR tool of the OP300 CBCT unit varied according to the post material tested. It was effective in reducing the expression of artefacts raised by the Ag-Pd post, mainly in the tooth regions affected by hypodense artefacts, regardless of the mandibular region.

CBCT image artefacts generated by implants located inside the field of view or in the exomass

OBJECTIVES

To compare artefacts in cone-beam computed tomography (CBCT) arising from implants of different materials located either inside the field of view (FOV) or in the exomass, and to test different image-acquisition parameters to reduce them.

METHODS

CBCT scans of a human mandible prepared with either a titanium, titanium-zirconium, or zirconia implant were acquired with the Planmeca ProMax utilizing FOV sizes of 8 × 5 cm and 4 × 5 cm, which placed the implant inside the FOV (8 × 5 cm) or in the exomass (4 × 5 cm). The scanning parameters considered three conditions of metal artefact reduction (MAR), disabled, low, and high, and 2 kVp levels (80 and 90). The standard deviation (SD) of grey values of regions of interest was obtained. The effects of implant material, implant position, MAR condition, kVp level, and their interactions were evaluated by Analysis of Variance (α = 5%).

RESULTS

The zirconia implant produced the highest SD values (more heterogeneous grey values, corresponding to greater artefact expression), followed by titanium-zirconium, and titanium. In general, implants in the exomass produced images with higher SD values than implants inside the FOV. MAR was effective in decreasing SD values, especially from the zirconia implant, only when the implant was inside the FOV. Images with 80 kVp had higher SD values than those with 90 kVp, regardless of the other factors (p < 0.05).

CONCLUSIONS

Implants in the exomass lead to greater artefact expression than when they are inside the FOV. Special attention should be paid to scanning parameters that reduce metal-related artefacts, such as MAR activation and increasing kVp. This is especially important with a zirconia implant inside the FOV.

Morphological characteristics of the mesiobuccal root in the presence of a second mesiobuccal canal: a micro-CT study

Objectives

This study investigated the internal morphology of mesiobuccal (MB) roots of maxillary molars with a second mesiobuccal (MB2) canal.

Materials and Methods

Forty-seven maxillary first or second molars from Brazilians were scanned using micro-computed tomography. The following measurements were obtained from the MB roots: root thickness, root width, and dentin thickness of the buccal aspect of the first mesiobuccal (MB1) canal, between the MB1 and MB2 canals, and the palatal aspect of the MB2 and MB1 canals at 3 mm from the root apex and in the furcation region. For statistical analysis, the Student’s t-test and analysis of variance with the post-hoc Tukey test were used (α = 0.05).

Results

In maxillary molars with an MB2 canal, MB roots were significantly thicker (p = 0.0014) and narrower (p = 0.0016) than in maxillary molars without an MB2 canal. The dentin thickness of the palatal aspect of the MB1 canal was also significantly greater than that of MB roots without an MB2 canal at 3 mm from the root apex (p = 0.0007) and in the furcation region (p < 0.0001). In the furcation region of maxillary molars with an MB2 canal, the dentin thickness between the MB1 and MB2 canals was significantly smaller than that in the buccal and palatal aspects (p < 0.0001).

Conclusions

The internal morphology of MB roots of maxillary molars with an MB2 canal revealed differences in dentin thickness, root diameter, and distance between the canals when compared with maxillary molars without an MB2 canal.

Digital file format does not influence the radiographic diagnosis of vertical root fracture

OBJECTIVE

To evaluate the influence of the file format of digital periapical radiographs on the diagnosis of vertical root fracture (VRF).

STUDY DESIGN

Periapical radiographic images of 34 single-rooted teeth-19 with VRF, and 15 without VRF were acquired using two digital systems-Digora Toto, and Digora Optime, and exported into four different file formats-TIFF, BMP, PNG, and JPEG, totaling 272 radiographs. The radiographs were assessed by five examiners for the detection of VRF, using a 5-point scale (1-definitely absent; 2-probably absent; 3-uncertain; 4-probably present; 5-definitely present). Diagnostic values of area under the ROC curve, specificity, and sensitivity for the diagnosis of VRF were calculated. The results were compared by two-way Analysis of Variance with post hoc Tukey's test. The intra- and inter-examiner agreements were measured by the Kappa test. The significance level was set at 5% for all analyses.

RESULTS

The values of intra-examiner agreement varied from moderate (0.56) to almost perfect (0.81), while the values of inter-examiner agreement varied from fair (0.29) to moderate (0.60). The image file format did not influence the diagnostic values for VRF for any of the radiographic systems tested (p > 0.05). Digora Toto had significantly greater values of area under the ROC curve than Digora Optime for all file formats (p = 0.001).

CONCLUSION

The image file format of periapical radiographs does not influence the diagnosis of VRF, regardless of the digital radiography system.

Influence of kilovoltage-peak and the metal artifact reduction tool in cone-beam computed tomography on the detection of bone defects around titanium-zirconia and zirconia implants

Purpose

The aim of this study was to assess the influence of kilovoltage-peak (kVp) and the metal artifact reduction (MAR) tool on the detection of buccal and lingual peri-implant dehiscence in the presence of titanium-zirconia (Ti-Zr) and zirconia (Zr) implants in cone-beam computed tomography (CBCT) images.

Materials and Methods

Twenty implant sites were created in the posterior region of human mandibles, including control sites (without dehiscence) and experimental sites (with dehiscence). Individually, a Ti-Zr or Zr implant was placed in each implant site. CBCT scans were performed using a Picasso Trio device, with variation in the kVp setting (70 or 90 kVp) and whether the MAR tool was used. Three oral radiologists scored the detection of dehiscence using a 5-point scale. The area under the receiver operating characteristic (ROC) curve, sensitivity, and specificity were calculated and compared by multi-way analysis of variance (α=0.05).

Results

The kVp, cortical plate involved (buccal or lingual cortices), and MAR did not influence any diagnostic values (P>0.05). The material of the implant did not influence the ROC curve values (P>0.05). In contrast, the sensitivity and specificity were statistically significantly influenced by the implant material (P<0.05) with Zr implants showing higher sensitivity values and lower specificity values than Ti-Zr implants.

Conclusion

The detection of peri-implant dehiscence was not influenced by kVp, use of the MAR tool, or the cortical plate. Greater sensitivity and lower specificity were shown for the detection of peri-implant dehiscence in the presence of a Zr implant.

Revisiting dynamic range and image enhancement ability of contemporary digital radiographic systems

OBJECTIVES

To assess the dynamic range and enhancement ability of radiographs acquired with contemporary digital systems.

METHODS

Five repeated periapical radiographs of human mandibles with an aluminium step-wedge were acquired using two sensor-based and three photostimulable phosphor plate-based systems and an X-ray unit at ten exposure times 0.020, 0.032, 0.063, 0.080, 0.100, 0.200, 0.320, 0.400, 0.500, and 0.630 s. All images had their brightness and contrast enhanced by two experienced oral and maxillofacial radiologists in consensus and were exported as both the original and enhanced file formats. Mean grey values were obtained from the aluminium steps and tabulated with their corresponding thicknesses for each exposure time, digital radiographic system, and file format. Images with saturated steps were excluded and the mean grey values from the remaining images were averaged to assess image brightness and the angular coefficient of the linear trendlines was generated from the relationship between mean grey values and their corresponding aluminium thicknesses to assess image contrast. Brightness and contrast values were compared using two-way ANOVA with post-hoc Tukey (α = 0.05).

RESULTS

Photostimulable phosphor plate-based digital radiographic systems had a broader dynamic range. Longer exposure times produced original images with lower brightness and variable contrast (p < 0.05). Subjective enhancement significantly increased or reduced brightness and/or contrast in some systems (p < 0.05).

CONCLUSIONS

Contemporary digital radiographic systems present different dynamic ranges and exposure-related brightness and contrast. Image enhancement may be a valuable tool at slightly suboptimal exposure times.

Mapping of a multilayer panoramic radiography device

OBJECTIVE

To map the shape, location, and thickness of the focal trough of a panoramic radiography device with a multilayer imaging program.

METHODS

An acrylic plate (148 × 148 × 3 mm) containing 1156 holes distributed in a matrix of 34 × 34 rows was placed in the OP300 Maxio at the levels of the maxilla and mandible. 20 metal spheres (3.5 mm in diameter) were placed on the holes of the plate under 15 different arrangements and panoramic images were acquired for each arrangement at 66 kV, 8 mA, and an exposure time of 16 s. The resulting panoramic radiographs from the five image layers were exported, the horizontal and vertical dimensions of the metal spheres were measured in all images using the Image J software, and the magnification and distortion rates of the spheres were calculated. All metal spheres presenting a magnification rate lower than 30% in both vertical and horizontal dimensions and a distortion rate lower than 10% were considered to map the focal troughs of each of the five image layers.

RESULTS

All panoramic image layers had a curved shape ranging from 39° to 51° for both dental arches and varied in position and thickness. The anterior region of maxilla was anteriorly displaced when compared to the anterior region of the mandible for all layers. Image layers are thicker at the level of the mandible than those at the level of the maxilla; also, inner layers were thinner and outer layers were thicker.

CONCLUSION

All image layers in the studied panoramic radiography device had a curved shape and varied in position and thickness. The anterior region of maxilla was anteriorly displaced when compared to that of the mandible for all layers.

Which factors related to apical radiolucency may influence its radiographic detection? A study using CBCT as reference standard

Objectives

This study aimed to evaluate the detection rate of apical radiolucencies in 2-dimensional images using cone-beam computed tomography (CBCT) as the reference standard, and to determine which factors related to the apical radiolucencies and the teeth could influence its detection.

Materials and Methods

The sample consisted of exams of patients who had panoramic (PAN) and/or periapical (PERI) radiography and CBCT. The exams were assessed by 2 oral radiologists and divided into PAN+CBCT (227 teeth–285 roots) and PERI+CBCT (94 teeth–115 roots). Radiographic images were evaluated for the presence of apical radiolucency, while CBCT images were assessed for presence, size, location, and involvement of the cortical bone (thinning, expansion, and destruction). Diagnostic values were obtained for PERI and PAN.

Results

PERI and PAN presented high accuracy (0.83 and 0.77, respectively) and specificity (0.89 and 0.91, respectively), but low sensitivity, especially for PAN (0.40 vs. 0.65 of PERI). The size of the apical radiolucency was positively correlated with its detection in PERI and PAN (p < 0.001). For PAN, apical radiolucencies were 3.93 times more frequently detected when related to single-rooted teeth (p = 0.038). The other factors did not influence apical radiolucency detection (p > 0.05).

Conclusions

PERI presents slightly better accuracy than PAN for the detection of apical radiolucency. The size is the only factor related to radiolucency that influences its detection, for both radiographic exams. For PAN, apical radiolucency is most often detected in single-rooted teeth.

Do the location and dimensions of the mental foramen differ among individuals of different facial types and skeletal classes? A CBCT study

STATEMENT OF PROBLEM

Knowledge about the location and dimensions of the mental foramen is important for surgical planning and implant placement in the posterior mandibular region.

PURPOSE

The purpose of this clinical study was to assess the location and dimensions of the mental foramen in individuals of different facial type, skeletal class, and sex by means of cone beam computed tomography (CBCT) images.

MATERIAL AND METHODS

CBCT images of 142 individuals (72 women and 70 men) were classified according to the facial type (dolichocephalic, mesocephalic, or brachycephalic) and skeletal class (I, II, or III). The vertical and horizontal locations of each mental foramen were evaluated on panoramic reconstructions, and the greatest height and width of the mental foramen were determined on multiplanar reconstructions. Also, the distances from the mental foramen to the alveolar crest and to the inferior cortex of the mandible were obtained. The data were compared by using the Kruskal-Wallis test and multiway analysis of variance (α=.05).

RESULTS

The facial type, skeletal class, and sex did not influence the vertical (P=1.00) or the horizontal (P>.15) location of the mental foramen. The most frequent location of the mental foramen was between the first and second premolars and below their apices. The dimensions of the mental foramen were not influenced by the studied factors in men (P>.07); conversely, the mental foramen dimensions were influenced for women (P<.03).

CONCLUSIONS

The most frequent location of the mental foramen was between the first and second premolars and below their apices. An influence of the facial type and skeletal class was observed on the dimensions of the mental foramen in women.

Comparison of the expression of the volumetric alteration artifact in cylindrical and triangular fields of view in two cone-beam computed tomography devices

OBJECTIVE

To compare the expression of the volumetric alteration (VA) artifact between cylindrical and convex triangular fields of view (FOVs) using high-density materials in different positions in two cone-beam computed tomography (CBCT) devices.

MATERIALS AND METHODS

Cylinders of five high-density materials (amalgam, chromium-cobalt, gutta-percha, titanium, and zirconium) with known physical volume were individually submitted to CBCT acquisition in four positions inside a polymethylmethacrylate phantom using two different FOV shapes (convex triangular and cylindrical) on the Veraviewepocs® R100 (R100) and Veraview® X800 (X800) devices. Two oral radiologists obtained the tomographic volumes by segmenting each cylinder. The difference between the tomographic and physical volumes corresponded to the VA. These values were analyzed by intraclass correlation coefficient and analysis of variance for repeated measures with Tukey post hoc test (α = 5%).

RESULTS

The FOV influenced the VA only in the X800 device (p = 0.014): the VA in the triangular FOV was greater than in the cylindrical FOV. The VA in the triangular FOV of the X800 device was greater than the R100 device (p < 0.0001). The material influenced the expression of the VA only in the R100 device (p < 0.0001); gutta-percha presented the highest VA, being underestimated, and differing from the other materials (p < 0.01).

CONCLUSION

The triangular FOV increased the VA of high-density materials in the X800 device.

CLINICAL RELEVANCE

It is important to know if there is an influence on the volumetric alteration artifact of dental materials due to the different image formation geometry in the convex triangular FOV.

Comparison of distance of upper central incisor root and incisive canal in different sagittal and vertical skeletal patterns and sex: A retrospective CBCT study

INTRODUCTION

To evaluate the influence of sagittal and vertical skeletal patterns (skeletal classes and facial profiles), and sex on the distance between upper central incisors roots and incisive canal.

MATERIAL AND METHODS

Cone-beam computed tomography exams of 172 patients were classified into skeletal classes I, II, and III and according to the facial profile into mesofacial, brachyfacial, and dolichofacial. In sagittal reconstructions, linear measurements were done between central incisors roots and incisive canal at three levels: incisive foramen opening, intermediate region, and the region close to the apex of upper central incisors. In axial reconstructions, measurements of incisive canal width and distance between the roots were obtained. Analysis of Variance (three-way ANOVA) was used to evaluate measurement differences in relation to skeletal classes, facial profiles, and sex.

RESULTS

The distance between upper central incisors roots and incisive canal anterior region was little influenced by sagittal and vertical skeletal patterns and sex. Men had significantly greater incisive canal (mean=2.85mm; SD=1.18) width compared to women (mean=2.40mm; SD=1.04), regardless of skeletal class and facial profile (P<0.05). In general, inter-root distance between medial points of central incisors roots and incisive canal opening was greater in the region close to upper central incisors apex (mean=3.84mm; SD=1.44) than in incisive foramen opening (2.44mm; SD=1.04), (P<0.05).

CONCLUSIONS

The distance between upper central incisors roots and incisive canal is little influenced by sagittal and vertical skeletal patterns and sex.

Do the dimensions of the hard palate have a relationship with the volumes of the upper airways and maxillary sinuses? A CBCT study

Background

As the hard palate is a central structure of the skull, and its close relationship with the nasal cavity, oral cavity, and maxillary sinuses, it would be of interest to study if there is a relationship between this bone and other structures of the stomatognathic system. Thus, this study aimed to assess the dimensions of the hard palate and associate them with sex, and skeletal and breathing patterns. Also, to investigate if there is a relationship between these dimensions and the volumes of the upper airways and maxillary sinuses.

Methods

Two hundred and ninety-eight CBCT scans of patients were classified according to sex, and skeletal and breathing patterns. Then, the linear dimensions of width and height of the hard palate at the regions of the first premolars and first molars, and the volumes of the upper airways and maxillary sinuses were measured using the CS 3D Imaging and ITK-SNAP software, respectively. Data were submitted to multi-way analysis of variance and linear regression, with a significance level of 5% (α = 0.05).

Results

Sex and facial type influenced the hard palate dimensions (p < 0.05). Males had greater width and height of the hard palate than females (p < 0.0001). It was observed greater width for brachycephalics at the first premolars region (p = 0.0032), and greater height for dolichocephalics at the first premolars (p = 0.0154) and first molars (p = 0.0038) regions. Skeletal malocclusion and breathing pattern did not influence the measurements of the hard palate (p > 0.05). There was a significant relationship between the width and height of the hard palate at the premolar’s region and the total volume of the upper airways (p = 0.018, and p = 0.038), and between both dimensions of the hard palate at the molar’s region and the total volume of the maxillary sinuses (p < 0.0001).

Conclusions

The hard palate dimensions are influenced by sex and facial type, but not by skeletal malocclusion or breathing pattern. Also, there is an association between these dimensions and the volumes of the upper airways and maxillary sinuses.

Distortion or magnification? An in vitro cone-beam CT study of dimensional changes of objects with different compositions

OBJECTIVES

To assess whether dimensional changes occur as shape distortion (unevenly), contraction or magnification (evenly) in cone beam computed tomography (CBCT) considering materials, anatomical regions and metal artefact reduction algorithms.

METHODS

Four cylinders of amalgam (Am), cobalt-chromium (Co-Cr), gutta-percha (Gu), titanium (Ti) and zirconium (Zi) were inserted inside a polymethylmethacrylate phantom in anterior and posterior regions for acquisitions in Picasso Trio and OP300 with MAR enabled and disabled. Two observers measured the dimensions of each cylinder in three axes: Y (height), Z (antero posterior diameter) and X (latero-lateral diameter). Repeated measures ANOVA with Tukey post-hoc test compared the data (α = 5%).

RESULTS

Shape distortion occurred for all materials in anterior region of Picasso Trio without MAR (p < 0.05). With MAR enabled, Gu and Ti contracted (p ≥ 0.05), while the others showed distortion (p < 0.05). In posterior region, all materials distorted in both MAR conditions (p < 0.05), except Gu, which magnified without MAR (p ≥ 0.05) and contracted unevenly with MAR (p < 0.05). In anterior region of OP300, all materials magnified without MAR, (p ≥ 0.05) and had shape distortion with MAR (p < 0.05). In posterior region, only Am showed magnification without MAR (p ≥ 0.05), while all materials presented shape distortion with MAR (p < 0.05).

CONCLUSION

Dimensional changes of high-density materials in CBCT can be either a magnification, a contraction or a distortion; the last condition is the most prevalent. Furthermore, changes differ considering material, anatomical region and MAR condition.

Influence of different viewing conditions on the detection of fractured endodontic instruments using periapical radiographs at 3 projection angles

OBJECTIVES

The objective of this study was to assess the influence of ambient lighting levels and horizontal viewing angle (HVA) on the radiographic detection of fractured endodontic instruments in root canals in extracted human mandibular molars.

STUDY DESIGN

Thirty-two root canals were selected. Endodontic instrument fracture was induced in 24 canals, and all canals were endodontially treated. Periapical radiographs were obtained at orthoradial, mesioradial, and distoradial projection angles. Five oral radiologists examined the radiographs for detection of fractured endodontic instruments under 3 ambient lighting levels (high, 450 lux; medium, 28 lux; and low, 2.5 lux) and 3 HVAs (90°, 67.5°, and 45°). Area under the receiver operating characteristic curve (AUROC), accuracy, sensitivity, and specificity were calculated and compared by 2-way analysis of variance using Tukey post hoc tests (α = .05).

RESULTS

AUROC data indicated that ambient lighting (P = .739) and HVA (P = .238) did not significantly influence the detection of fractured endodontic instruments. Overall mean diagnostic values were 0.745, 0.57, 0.46, and 0.90 for AUROC, accuracy, sensitivity, and specificity, respectively.

CONCLUSIONS

The viewing conditions assessed in this study did not influence the radiographic detection of fractured endodontic instruments in root canals.

Influence of skeletal class and facial type on nose dimensions in a Brazilian subpopulation: a CBCT study

Evaluating factors that may influence the nose dimensions and, therefore, contribute to the singularity of a person, is important for obtaining a precise facial reconstruction (FR) in forensic anthropology. Thus, the aim in this study was to evaluate the influence of sex, skeletal class, and facial type on nose dimensions of Brazilian individuals using cone-beam computed tomography (CBCT) scans. CBCT images of 54 males and 67 females were classified according to skeletal class (class I, II, or III) and facial type (brachycephalic, dolichocephalic and mesocephalic). Linear and angular measurements of the nose were performed using the CS 3D Imaging software. The measurements obtained for males and females were compared by one-way ANOVA. Two-way ANOVA was used to compare the measurements in the different skeletal classes and facial types. Significance level was set at 5%. All linear measurements were greater in males (p < 0.05); the angular measurements, however, did not differ between sexes (p > 0.05). Linear and angular measurements of class III males were significantly different from the other classes; the same was observed for the angular measurements in females (p < 0.05). Regarding facial types, some linear measurements were significantly greater in dolichocephalics males (p < 0.05). For females, there was no influence of facial type (p > 0.05), except for the nasal convexity angle. Nose dimensions differed in specific points among different skeletal classes and facial types, and there was sexual dimorphism in all linear nose dimensions. This information may be applicable for nose reconstructions, allowing more reliable FR.

Artificial intelligence for detection of periapical lesions on intraoral radiographs: Comparison between convolutional neural networks and human observers

OBJECTIVE

The aim of this study was to compare the diagnostic performance of convolutional neural networks (CNNs) with the performance of human observers for the detection of simulated periapical lesions on periapical radiographs.

STUDY DESIGN

Ten sockets were prepared in bovine ribs. Periapical defects of 3 sizes were sequentially created. Periapical radiographs were acquired of each socket with no lesion and with each lesion size with a photostimulable storage phosphor system. Radiographs were evaluated with no filter and with 6 image filter settings. A CNN architecture was set up using Keras-TensorFlow. Separate CNNs were evaluated for randomly sampled training/validation data and for data split up by socket (5-fold cross-validation) and filter (7-fold cross-validation). CNN performance on validation data was compared with that of 3 oral radiologists for sensitivity, specificity, and area under the receiver operating characteristic curve (ROC-AUC).

RESULTS

Using random sampling, the CNN showed perfect accuracy for the validation data. When data were split up by socket, the mean sensitivity, specificity, and ROC-AUC values were 0.79, 0.88, and 0.86, respectively; when split up by filter, they were 0.87, 0.98, and 0.93, respectively. For radiologists, the values were 0.58, 0.83, and 0.75, respectively.

CONCLUSIONS

CNNs show promise in periapical lesion detection. The pretrained CNN model yielded in this study can be used for further training on larger samples and/or clinical radiographs.