Matheus Lima Oliveira

Relationship between bone mineral density and trabecular bone pattern in postmenopausal osteoporotic Brazilian women

ObjectivesThe aim of this study is to evaluate the relative efficacy of the mandibular trabecular bone in detecting osteoporotic-associated bone changes in Brazilian women.Materials and methodsSeventy-three digital panoramic radiographs of healthy and osteoporotic postmenopausal women were used. Regions of interest were selected in the mandibular angle and body of the panoramic images, which were analyzed for fractal dimension (FD) and pixel intensity (PI). Statistical analysis evaluated the distribution pattern, compared normal with osteoporotic patients and the right with the left mandible, and assessed the relationship between FD and PI. The significance level was set at 0.05.ResultsFD and PI values were significantly different (p < 0.05) between normal and osteoporotic patients for the right and left mandibular angle and for the left mandibular body. There was no significant difference (p > 0.05) between the right and left mandibular angle for FD and PI, but a significant difference (p < 0.05) was observed on the mandibular body for PI values. FD and PI values presented positive correlation.ConclusionsThe mandibular trabecular bone was effective in detecting osteoporotic changes, with the exception of the right mandibular body.Clinical relevanceMandibular trabecular bone shows a promising attempt of accurate detection of osteoporotic changes in some regions of the jaws. Fractal analysis and pixel intensity had strong positive correlation.

Influence of anatomical location on CT numbers in cone beam computed tomography

OBJECTIVE To assess the influence of anatomical location on computed tomography (CT) numbers in mid- and full field of view (FOV) cone beam computed tomography (CBCT) scans. STUDY DESIGN Polypropylene tubes with varying concentrations of dipotassium hydrogen phosphate (K₂HPO₄) solutions (50-1200 mg/mL) were imaged within the incisor, premolar, and molar dental sockets of a human skull phantom. CBCT scans were acquired using the NewTom 3G and NewTom 5G units. The CT numbers of the K₂HPO₄ phantoms were measured, and the relationship between CT numbers and K₂HPO₄ concentration was examined. The measured CT numbers of the K₂HPO₄ phantoms were compared between anatomical sites. RESULTS At all six anatomical locations, there was a strong linear relationship between CT numbers and K₂HPO₄ concentration (R(2)>0.93). However, the absolute CT numbers varied considerably with the anatomical location. CONCLUSION The relationship between CT numbers and object density is not uniform through the dental arch on CBCT scans.

Influence of exposure factors on the variability of CBCT voxel values: a phantom study

OBJECTIVES To assess the influence of milliamperage and kilovolt peak (kVp) on the variability of cone beam CT (CBCT) voxel values. METHODS CBCT scans were obtained from radiographic phantoms in varying concentrations of dipotassium hydrogen phosphate solutions (200-1200 mg ml(-1)) under different protocols of milliamperage and kVp. In addition, scans were performed with and without a dental implant and exo-mass. The variability of CBCT voxel values was measured on each scan, and factorial analysis of variance and the post hoc Tukey test were performed (α = 0.05). Linear regression was performed to assess the relationship between voxel value variability and dipotassium hydrogen phosphate concentration. RESULTS milliamperage and the presence of a dental implant did not produce significant interference (p = 0.28 and 0.87, respectively) in voxel value variability. Scans at the highest kVp value presented a significant reduction (p ≤ 0.0001) in voxel value variability when only exo-mass was not present. Voxel value variability was not influenced by exo-mass in scans at the highest levels of milliamperage and kVp. The presence of exo-mass produced a significant reduction (p ≤ 0.0001) in voxel value variability in most of the scans. Higher concentrations yielded greater variations in voxel values in all scans, except for those operating at the highest levels of mAs and kVp. CONCLUSIONS mAs did not influence the variability of CBCT voxel values; higher kVp reduced such variability when only the object was smaller than the field of view.

Influence of cone-beam computed tomography image artifacts on the determination of dental arch measurements

OBJECTIVE To compare dental plaster model (DPM) and cone-beam computed tomography (CBCT) in the measurement of the dental arches, and investigate whether CBCT image artifacts compromise the reliability of such measurements. MATERIALS AND METHODS Twenty patients were divided into two groups based on the presence or absence of metallic restorations in the posterior teeth. Both dental arches of the patients were scanned with the CBCT unit i-CAT, and DPMs were obtained. Two examiners obtained eight arch measurements on the CBCT images and DPMs and repeated this procedure 15 days later. The arch measurements of each patient group were compared separately by the Wilcoxon rank sum (Mann-Whitney U) test, with a significance level of 5% (α  =  .05). Intraclass correlation measured the level of intraobserver agreement. RESULTS Patients with healthy teeth showed no significant difference between all DPM and CBCT arch measurements (P > .05). Patients with metallic restoration showed significant difference between DPM and CBCT for the majority of the arch measurements (P > .05). The two examiners showed excellent intraobserver agreement for both measuring methods with intraclass correlation coefficient higher than 0.95. CONCLUSION CBCT provided the same accuracy as DPM in the measurement of the dental arches, and was negatively influenced by the presence of image artifacts.

Efficacy of several digital radiographic imaging systems for laboratory determination of endodontic file length

AIM To compare the efficacy of different digital radiographic imaging systems for determining the length of endodontic files. METHODOLOGY K-type endodontic files were introduced into the canals of 40 extracted human permanent single-rooted teeth and fixed in place at random lengths. The teeth were radiographed using Digora Optime, CygnusRay MPS and CDR Wireless digital imaging systems. Six observers measured every file length in all the images and repeated this procedure in 50% of the image samples, and assigned a score to the level of difficulty found. Analysis of variance for differences between digital systems and Tukeys test were performed. The level of intraobserver agreement was measured by intraclass correlation. The assigned scores were evaluated by Kruskal-Wallis and Dunns tests. RESULTS The CDR Wireless values did not differ significantly from the actual lengths and the CygnusRay MPS values. The Digora Optime system was significantly different from the others and overestimated the values (P ≤ 0.05). The Digora Optime was significantly easier to use for taking measurements and the CygnusRay MPS the most difficult (P ≤ 0.05). All digital radiographic imaging systems showed excellent agreement with the Intraclass Correlation Coefficient >0.95. CONCLUSIONS The three digital radiographic imaging systems were precise. The CDR Wireless system was significantly more accurate in determining endodontic file lengths, and similarly to Digora Optime, was considered the least difficult to use when assessing endodontic file lengths.

Assessment of CT numbers in limited and medium field-of-view scans taken using accuitomo 170 and veraviewepocs 3De cone-beam computed tomography scanners

Purpose To assess the influence of anatomic location on the relationship between computed tomography (CT) number and X-ray attenuation in limited and medium field-of-view (FOV) scans. Materials and Methods Tubes containing solutions with different concentrations of K2HPO4 were placed in the tooth sockets of a human head phantom. Cone-beam computed tomography (CBCT) scans were acquired, and CT numbers of the K2HPO4 solutions were measured. The relationship between CT number and K2HPO4 concentration was examined by linear regression analyses. Then, the variation in CT number according to anatomic location was examined. Results The relationship between K2HPO4 concentration and CT number was strongly linear. The slopes of the linear regressions for the limited FOVs were almost 2-fold lower than those for the medium FOVs. The absolute CT number differed between imaging protocols and anatomic locations. Conclusion There is a strong linear relationship between X-ray attenuation and CT number. The specific imaging protocol and anatomic location of the object strongly influence this relationship.

Influence of Tooth Orientation on the Detection of Vertical Root Fracture in Cone-beam Computed Tomography

Introduction: The purpose of this study was to assess the influence of tooth orientation in relation to the projection plane of the x‐rays on the detection of vertical root fracture (VRF) with different filling materials using cone‐beam computed tomographic (CBCT) imaging. Methods: Thirty single‐rooted human teeth were endodontically instrumented, and VRF was induced in half of the sample. The roots were individually placed in the dental socket of a phantom head composed of a dry human skull and mandible, and CBCT images were obtained of each root with the longitudinal axis in 2 orientations: perpendicular and parallel to the projection plane of the x‐rays. Also, each root was scanned under 3 filling conditions: without filling material, with gutta‐percha, and with a metal post. Radiation doses at specific anatomic regions of the phantom were obtained for the 2 orientations. Five radiologists evaluated all images and rated the fractures on a 5‐point scale. The sensitivity, specificity, accuracy, and positive and negative predictive values were calculated. The area under the receiver operating characteristic curve and the dosimetric outcomes for each root orientation and filling material were compared, respectively, with 2‐way and 1‐way analysis of variance with the post hoc Tukey test (&agr; = 0.05). Results: There was no significant difference (P ≥ .05) in the detection of VRF between root orientations regardless of the filling material. Az values were significantly lower (P < .05) in the presence of gutta‐percha and a metal post. The root orientation varied the absorbed dose at some anatomic regions. Conclusions: The orientation of the tooth in relation to the projection plane of the x‐rays does not influence the detection of VRF using CBCT imaging irrespective of the intracanal material. Highlights:Tooth orientation does not influence the detection of vertical root fracture using cone‐beam computed tomographic (CBCT) imaging.Highly dense objects with high atomic numbers impair the detection of root fracture.Patient positioning for CBCT scanning may affect the absorbed dose of different anatomic regions.

Brazilian young dental practitioners' use and acceptance of digital radiographic examinations

Purpose The aim of this study was to investigate the use and acceptance of digital radiographic examinations by Brazilian dental practitioners in daily practice and to evaluate the advances that have occurred over the past 5 years. Materials and Methods Dental practitioners enrolled in extension courses at the Piracicaba Dental School, University of Campinas, Brazil, responded to a self-administered questionnaire in the years 2011 and 2015. They were asked about sociodemographic factors and their knowledge and use of digital radiographic examinations. Descriptive analysis was performed, as well as the chi-square and Fisher exact tests, with a significance level of 5% (α=0.05). Results A total of 181 participants responded to the questionnaire in the years 2011 and 2015. Most of the respondents worked in private practice, had graduated within the last 5 years, and were between 20 and 30 years old. In 2011, 55.6% of respondents reported having ever used digital radiographic examinations, while in 2015 this number increased significantly to 85.4% (p<.0001), out of which 71.4% preferred it to conventional images. Moreover, 21.4% of respondents reported having used digital radiographic examinations for more than 3 years. A significant increase in use of intraoral digital radiography (p=0.0316) was observed in 2015. In both years, image quality and high cost were indicated, respectively, as the main advantage and disadvantage of digital radiographic examinations. Conclusion This study showed that digital radiology has become more common in Brazil over the past 5 years. Most of the Brazilian dental practitioners evaluated in 2015 used digital radiographic examinations.

Assessment of three methods of geometric image reconstruction for digital subtraction radiography.

OBJECTIVES To evaluate three methods of geometric image reconstruction for digital subtraction radiography (DSR). METHODS Digital periapical radiographs were acquired of 24 teeth with the X-ray tube at 6 different geometric configurations of vertical (V) and horizontal (H) angles: V0°H0°, V0°H10°, V10°H0°, V10°H10°, V20°H0° and V20°H10°. All 144 images were registered in pairs (Group V0°H0° + 1 of the 6 groups) 3 times by using the Emago(®) (Oral Diagnostic Systems, Amsterdam, Netherlands) with manual selection and Regeemy with manual and automatic selections. After geometric reconstruction on the two software applications under different modes of selection, all images were subtracted and the standard deviation of grey values was obtained as a measure of image noise. All measurements were repeated after 15 days to evaluate the method error. Values of image noise were statistically analyzed by one-way ANOVA for differences between methods and between projection angles, followed by Tukeys test at a level of significance of 5%. RESULTS Significant differences were found between most of the projection angles for the three reconstruction methods. Image subtraction after manual selection-based reconstruction on Regeemy presented the lowest values of image noise, except on group V0°H0°. The groups V10°H0° and V20°H0° were not significantly different between the manual selection-based reconstruction in Regeemy and automatic selection-based reconstruction in Regeemy methods. CONCLUSIONS The Regeemy software on manual mode revealed better quality of geometric image reconstruction for DSR than the Regeemy on automatic mode and the Emago on manual mode, when the radiographic images were obtained at V and H angles used in the present investigation.

Gray scale inversion in digital image for measurement of tooth length

The aim of this study was to assess the applicability of gray scale inversion in performing digital linear endodontic measurements. Standardized digital images were taken of 40 extracted human permanent single-rooted teeth with K-files size 15 placed at different lengths in the root canal, using the CDR Wireless(®) digital system. All images were treated with Positive, a digital tool that inverts the grayscale value. Eight radiologists measured the distance between the lower limit of the rubber stop and the tip of the file on both original and positive images. After 15 days, they repeated this procedure in 50% of the image samples. The intra- and inter-examiner agreement was analyzed by intraclass correlation test, and the comparison between the two image groups and the actual lengths by the Students t-test (α=0.05). Intra- and inter-examiner evaluation showed high reproducibility (r>0.95) of both original and positive images. No statistically significant differences (p>0.05) were found between measurements performed on original and positive images, but both differed significantly from the actual lengths (p<0.05). Gray scale inversion has low applicability in measuring endodontic files, since it did not improve the accuracy of measurements.