PreXion 3D Research Articles

Influence of a Metal Artifact Reduction Filter on the Diagnostic Accuracy of Complete and Incomplete Vertical Root Fractures

IntroductionThis study aimed to assess the influence of the e-vol DX BAR filter on the diagnostic accuracy of complete and incomplete vertical root fractures (VRFs). MethodsTwenty single-rooted teeth were selected. The tooth crowns were removed, and the root canals were prepared up to a 40/.06 instrument (ProTaper Next). Each specimen was scanned in a Prexion 3D cone-beam computed tomography (CBCT) device, in a dry human skull, in 4 different situations: no root canal filling, gutta-percha, fiberglass post, and metal post. The specimens were fractured in a universal testing machine by using a customized wedge. Each specimen was reinspected to confirm the presence of incomplete VRFs. Another set of CBCT scans was performed. Then, the fractures were completed in the universal testing machine, the teeth were reinspected, and the CBCT images were acquired again. Images were assessed by using the e-Vol DX software system, with the BAR filter and with the original images, for the diagnosis of VRFs. Statistical analysis was performed by using the DeLong and McNemar tests for the comparison of the area under the receiver operating characteristic curves (AUC), accuracy, sensitivity, and specificity values. ResultsThe use of the BAR filter did not improve the diagnostic values of AUC, accuracy, sensitivity, and specificity in both fracture patterns (P > .05). Incomplete VRFs presented significantly lower AUC, accuracy, and sensitivity compared with complete VRFs (P < .0001). ConclusionsThe BAR filter did not improve the diagnostic accuracy of VRFs. The intracanal materials also did not influence the diagnosis. Incomplete VRFs were highly associated with a decrease in sensitivity.

Quantitative and qualitative comparisons of pulp cavity volumes produced by cone beam computed tomography and micro-computed tomography through semiautomatic segmentation: An ex vivo investigation

The aim of this study was to measure the volume and visually assess 3-dimensional (3D) virtual models of pulp cavities obtained through semiautomatic segmentation on images from 6 cone beam computed tomography (CBCT) units compared with the reference standard of micro-CT. Fifteen mandibular premolar teeth were scanned with 6 CBCT units: Prexion 3D Elite, i-CAT Next Generation, NewTom 5G, Cranex 3D, 3Shape X1, and Orthophos SL 3D, using the smallest available field of view and highest resolution settings. Pulp cavity volumes were quantitatively assessed by 2 calibrated examiners. The volumes from each CBCT unit were compared with micro-CT. Qualitative assessment of the 3D reconstructions was also performed. Repeated-measures analysis of variance and the Friedman test compared the CBCT reconstructions to micro-CT. Intra- and interexaminer agreements were calculated with the intraclass correlation coefficient and kappa statistic. The CBCT-based volumes were all significantly larger than micro-CT (P ≤ .0061). Prexion, X1, and Orthophos provided the segmentations that most closely resembled the reference standard. Intra- and interexaminer agreements ranged from good to excellent for quantitative measurements. Interexaminer agreement for qualitative evaluation was substantial. Semiautomatic segmentation of CBCT images is a feasible method to produce virtual 3D models of the pulp cavity. Prexion, X1, and Orthophos were the CBCT units that resulted in 3D reconstructions most similar to the reference standard.

The prevalence and characteristics of external cervical resorption based on cone-beam computed tomographic imaging: a cross-sectional study.

This study investigated the prevalence and characteristics of external cervical resorption (ECR) regarding sex, age, tooth, stages of progression, and portal of entry, using cone-beam computed tomography (CBCT) scans. CBCT scans of 1,313 patients from a Brazilian subpopulation comprising 883 female and 430 male patients (mean age, 55.2 years), acquired using a PreXion 3D CBCT unit, were evaluated. All permanent teeth included in the scans were evaluated for the presence of ECR according to the 3-dimensional classification and the portal of entry. The association between the presence of ECR and the factors studied was assessed using the χ2 test. Intra-observer agreement was analyzed with the kappa test (α = 0.05). In total, 6,240 teeth were analyzed, of which 84 (1.35%) were affected by ECR. A significant association was found between the presence of ECR and sex, with a higher prevalence in male patients (p = 0.002). The most frequently affected teeth were the mandibular and maxillary central incisors. The most common height was the mid-third of the root. For the portal of entry, 44% of cases were on the proximal surfaces, 40.5% on the lingual/palatal surface and 15.5% on the buccal surface. Intra-observer agreement was excellent. The prevalence of ECR was 1.35%, with a higher prevalence in male patients and a wide age distribution. The mandibular and maxillary central incisors were the most commonly affected teeth, and cases of ECR most frequently showed a height into the mid-third of the root and proximal entry.

Assessment of Trabecular Bone During Dental Implant Planning using Cone-beam Computed Tomography with High-resolution Parameters

Background: Cone-Beam Computed Tomography (CBCT) with high-resolution parameters may provide an acceptable resolution for bone assessment. Objectives: The purpose of this study is to assess trabecular bone using two cone-beam computed tomography (CBCT) devices with high-resolution parameters in comparison to micro-computed tomography (µCT). Methods: Bone samples (n=8) were acquired from dry mandibles and scanned by two CBCT devices: 1) VV (Veraview R100, Morita; FOV 4x4, 75kV, 9mA, voxel size 0.125µm); and PR (Prexion 3D, Prexion; FOV 5x5, 90kV, 4mA, 37s, voxel size 108µm). Gold-standard images were acquired using µCT (SkyScan 1272; Bruker; 80kV, 125mA, voxel size 16µm). Morphometric parameters (BvTv- Bone Volume Fraction, BsBv- Trabecular specific surface, TbTh- Trabecular thickness and TbSp- Trabecular separation) were measured. Statistical analysis was performed within ANOVA, Spearman Correlation test and Bland-Altmann plots with a statistical significance level at p=0.05. Results: CBCT devices showed similar BvTv values in comparison to µCT. No statistical difference was found for BvTv parameters assessed by CBCT devices and µCT. BsBv values were underestimated by CBCT devices (p&lt;0.01), whereas TbTh and TbSp values were overestimated by them (p&lt;0.01). Positive correlations were found between VV and µCT measurements for BvTv (r2= 0.65, p=0.00), such as between PR and µCT measurements for TbSp (r2= 0.50, p=0.04). For BsBv measurements, PR was negatively correlated with µCT (r2= -0.643, p=0.01). Conclusion: The evaluated CBCT device was able to assess trabecular bone. However, bone parameters were under or overestimated in comparison to µCT.

Application of computed tomography dose index as dosimetric parameter in dental tomography

ABSTRACT Objective Quantify the CTDI from a reference beam, correcting this value for several beam widths from the ratio of CTDI100 values measured in the air, and verifying the underestimation of the dose comparing CTDI100 and CTDI300, applied to dental CBCT. Methods i-CAT and Prexion 3D tomographs, 100mm pencil ionization chamber, electrometer. Firstly for beam above 40 mm, CTDIW,NT from CTDIW,Ref, multiplied by the ratio of CTDIAR measurements to N.T widths and reference, was estimated. In second, CTDI100 and CTDI300 are obtained by displacing the ionization chamber along the beam with spacing intervals equal to 100 mm to cover sufficiently large integration intervals for CBCT protocols, and a comparison is made through the modified efficiency. Results CTDIAR,100,Ref averaged 53% higher than CTDIW,Ref, due to attenuation of the beam by the simulator object, and the ratio between CTDIAR,100,Ref and CTDIW,Ref is greater than 1, being this constant relationship and validating the method for dosimetry in quality control tests. For the second method, CTDI100 greatly underestimates the dose deposited on the central axis, where CTDI300 covers all beam sizes and stands out in relation to CTDI100 to more accurately quantify the radiation levels emitted. Conclusions The IEC method is applicable to quality control, facilitating practice, and optimizing time and resources. CTDI300 is a better dose descriptor than CTDI100, and should be implemented for CBCT modalities when used.

Vertucci’s Root Canal Configuration of 14,413 Mandibular Anterior Teeth in a Brazilian Population: A Prevalence Study Using Cone-beam Computed Tomography

IntroductionThis cone-beam computed tomographic (CBCT)-based study evaluated the root canal configurations of mandibular anterior teeth in a large Brazilian population, along with the influence of sex and the frequency of symmetry between the contralateral teeth. MethodsOverall, 2543 CBCT scans, including those of 4773 lower central incisors (LCIs), 4835 lower lateral incisors (LLIs), and 4805 lower canines (LCs), were analyzed. The scans were obtained from a private radiologic clinic using the PreXion 3D device (Yoshida Dental Mfg Co, Ltd, Tokyo, Japan) with a 0.14-mm voxel size; exposure parameters of 90 kV, 4 mA, and 19 seconds; and a field of view of 80 × 80 mm. Root canal anatomy was analyzed according to the Vertucci classification. Sex influence on the canal distribution and symmetry between the contralateral teeth were analyzed. The data were analyzed statistically and were considered significant when P < .05. ResultsAll LCIs and LLIs had 1 root, whereas 2.4% of LCs had 2 roots. Two root canals were observed in approximately 20% of LCIs and LLIs and in approximately 11% of LCs. The most common configuration was type I followed by type III. Bilateral symmetry occurred in a majority of the individuals (ie, 91% in LCIs, 87% in LLIs, and 87% in LCs). No sex influence was noted with LLIs and LCs (P > .05). However, LCIs showed a higher prevalence of 2 canals in men (P < .05). ConclusionsThe prevalence of 2 root canals in the mandibular anterior teeth in Brazilians was approximately 20% for central and lateral incisors and 10% for canines.

Accuracy of three cone-beam CT devices and two software systems in the detection of vertical root fractures.

The aim of this study was to compare the accuracy of vertical root fracture (VRF) detection using three tomography devices and two software systems in teeth with different endodontic fillings. The sample consisted of 45 premolars divided into 3 groups: No filling (NF, n=15); Gutta percha (GP, n=15) and Metallic Post (MP, n=15). Cone-beam computed tomography (CBCT) images were acquired in Kodak 9000 3D, Orthopantomography 300 (OP300) and PreXion 3D devices, before and after induced root fractures. Two oral radiologists analyzed all images using InVivoDental and e-Vol DX software systems. The analysis was repeated after 15 days in 30% of the sample. Data analysis compared receiver operating characteristic (ROC) curves, as well the areas under the ROC curves. Accuracy, sensitivity, specificity, positive and negative predictive value were calculated according to each tomographic device and software. Intra- and interexaminer reliability were tested using the Kappa coefficient. The highest accuracy was seen in the image set from the PreXion 3D, using InVivo (0.96) or e-Vol DX (0.92) in image analysis. The OP300 device presented a similar performance of the PreXion 3D in teeth with different endodontic fillings. When using e-Vol DX, the accuracy of Kodak 9000 3D improved from 0.62 to 0.74. The PreXion 3D device is the most accurate when detecting VRF, with a performance similar to the OP300 in endodontic filled teeth. Kodak 9000 3D is indicated for teeth without fillings, with better accuracy using e-Vol DX software.

Anatomical evaluation of the nasopalatine canal using CBCT (Cone Beam Computed Tomography): Method validation in open source software

Objective: Development and validation (using open source software) of a method for volumetric and linear assessment of the nasopalatine channel (NPC) using cone beam computed tomography (CBCT). Materials and methods: This was an observational, cross-sectional study of 276 CBCTs. Acquisition was performed on a Prexion 3D computerized tomography scanner (manufacturer), using voxels of 0.08 mm and 0.14 mm, (with FOV at 5 and 12 cm). The images were compiled and divided in accordance with gender and the dental condition of the maxilla. Evaluation took place on a MacBook Pro computer using the Horos Project program (Version 3.3.5). Linear measurements and NPC volumetric evaluations were performed after correcting the orientation axes (sagittal and axial). The length and ROI volume tools were used. Results: The average age for men was 60.15 ± 11.94, for women it was 59.95 ± 10.63. Respectively, for men and women, the average NPC volume values ​​ were: 68.59 mm3 and 59.37 mm3 (p = 0.032), for length they were 10.08 mm and 8.84 mm (p = 0.000). Of the dentate participants, the NPC averages for volume for men and women were: 71.01 mm3 and 57.18 mm3 (p = 0.007), for length they were 10.26 mm and 9.14 mm (p = 0.001). In the edentulous, the average NPC lengths were 9.79 mm (men) and 8.37 mm (women) (p = 0.005). Conclusion: For linear and volumetric nasopalatine channel assessment, the post-processing method used in the Horos software was considered precise and easy-to-use.

Potential of a New Cone-Beam CT Software for Blooming Artifact Reduction.

This study evaluated the dimensions of intraradicular posts using a new cone beam CT (CBCT) software, and verified the potential of blooming artifact reduction. Sixty-three single-rooted human teeth were shaped, obturated, prepared for intracanal post placement and distributed into three groups: G1: anatomically customized prefabricated glass fiber posts; G2: low-fusion alloy posts; G3: gold alloy posts. After post fabrication and luting with RelyX U200®, specimens were sectioned axially at 9 mm from the root apex, and markings were made on the root surfaces (X-, Y- and Z-axes). The dimensions of the original posts (control group) were measured using a digital micrometer. CBCT scans of the teeth were obtained using a PreXion 3D Elite® scanner. Posts were measured on CBCT scans using DICOM files and the e-Vol DX software. A specific filter, Blooming Artefact Reduction (BAR), was developed to analyze intracanal posts. Statistical data were evaluated using the Van de Waerden nonparametric analysis of variance and, after that, normalized data were analyzed using the Tukey test. The level of significance was set at α = 5%. The measures of the anatomical prefabricated, low-fusion alloy and gold alloy intracanal posts obtained using the e-Vol DX CBCT software and a micrometer were not significantly different (p>0.05). The use of the BAR filter of the e-Vol DX software application did not induce any dimensional differences on CBCT scans of intracanal posts when compared with measurements made with a micrometer on original posts. The use of the BAR filter eliminated blooming artifacts.

Cone-Beam Computed Tomography Detection of Separated Endodontic Instruments

IntroductionThis study compared the accuracy, sensitivity, and specificity of different imaging diagnostic protocols, cone-beam computed tomography (CBCT) and digital periapical radiography (DPR), in identifying separated endodontic instruments in filled root canals. MethodsOne hundred eight root canals from 36 mandibular molars were prepared and obturated. Of these, 84 were filled without separated instruments, and 24 were filled with the presence of a separated instrument (stainless steel hand file or reciprocating instrument). Subsequently, different CBCT imaging protocols were acquired: i-CAT Classic (ICC) (0.25-mm isotropic voxel), i-CAT Next Generation (ICN) (0.125-mm isotropic voxel), and PreXion 3D (PXD) (0.09-mm isotropic voxel). Moreover, a DPR exam was obtained (08 mA, 70 kVp, and exposure time of 0.2 seconds). Two calibrated endodontists evaluated each image for the presence or absence of fractured files on a 5-point scale, ranging from definitely absent to definitely present. The accuracy, sensitivity, and specificity measures for each method were estimated. The data were evaluated by Fisher exact test and binomial test. ResultsNine instruments were identified in DPR (37.5%) and none in the CBCT protocols (P > .05). The type of instrument (stainless steel hand file or reciprocating instrument) did not influence the identification of the separated instrument (P > .05). This study showed that DPR is the most accurate and sensitive imaging technique, with 83.3% and 37.5%, respectively. ConclusionsDPR is the better imaging diagnostic exam to evaluate the presence of separated endodontic instruments inside a root canal in comparison with the ICC, ICN, and PXD tomographic protocols. However, most of the separated instruments were not identified.

Analysis of the internal anatomy of mandibular molars using different cone-beam computed tomography protocols

The aim of this study was to analyze the root canal anatomy variations of permanent mandibular molars using three different cone-beam computed tomography (CBCT) protocols. Material and methods: Thirty-five freshly extracted first and second mandibular molars were collected and subjected to three CBCT protocols: i-CAT Classic (ICC); i-CAT Next Generation (ICN), and PreXion 3D (PXD). Images were evaluated by two previously calibrated and experienced endodontists. The morphological root canal configurations were classified according to Vertucci. Data were analyzed for frequency, and the binomial and Kappa tests were then performed (α = 0.05). Results: ICC and ICN were able to diagnose a higher percentage of anatomical variations in the mesial roots. In this same root, Vertucci’s type V was the most prevalent, and in distal was the type I. In comparisons of CBCT techniques for agreement, significant differences in the mesial root canals were found in the following: ICC versus (vs) ICN; ICC vs PXD; and ICN vs PXD (p &lt;0.001). However, there were no statistical differences in the distal root canals (p &gt;0.05). The level of agreement in mesial roots was poor or absent, while in distal was moderate.

CBCT assessment of bone thickness in maxillary and mandibular teeth: an anatomic study.

The site of the sinus tract depends on the rate of resistance against abscess exudate drainage, bone morphology, and distance from the root apex to the outer cortical bone. Objective To assess apical bone thickness in buccal and palatal/lingual aspects of maxillary and mandibular teeth, using a high-resolution cone-beam computed tomography (CBCT) system.Methodology In total, 422 CBCT examinations were included in the study, resulting in a sample of 1400 teeth. The scans were acquired by PreXion 3D, with a high-resolution protocol. The bone thickness was taken as the distance between the center of the apical foramen and the buccal and lingual/palatal cortical bone. The quantitative variables were expressed as mean values±standard deviation. The independent samples were analyzed using the t-test or the Mann-Whitney test (p<0.05).Results The lowest mean value of bone thickness was observed in the buccal cortical bone of the upper canines (1.49 mm±0.86) and in the upper central incisors (1.59 mm±0.67). In premolar teeth, the lowest values were found in the buccal cortical bone of upper first premolars (1.13 mm±0.68). In the posterior teeth, the lowest values were found in the buccal cortical bone of upper first molars (1.98 mm±1.33). In the lower second molar region, the buccal cortical bone (8.36 mm±1.84) was thicker than the lingual cortical bone (2.95 mm±1.16) (p<0.05).Conclusions The lowest mean values of bone thickness are in the buccal cortical bone of the maxillary teeth. In the mandible, bone thickness is thinner in the buccal bone around the anterior and premolar teeth, and in the lingual aspect of mandibular molars. All these anatomic characteristics could make the occurrence of the sinus tract more susceptible in these specific regions of the maxillary and mandibular alveolar bone.

Internal configuration of maxillary molars in a subpopulation of Brazil's Northeast region: A CBCT analysis.

The present study aimed to evaluate the internal configuration of the maxillary molars of a population from the Northeast region of Brazil. Cone-beam computed tomography (CBCT) exams from 512 patients (1501 teeth) were evaluated regarding the anatomical configuration of the root canal system, according to Vertucci's classification. The images were obtained using a Prexion 3D scanner operating at 90 kVp and 4 mA. The voxel size was 0.125 mm and the cut thickness was 1 mm. The images were then analyzed in the Prexion 3D Viewer software. The data were analyzed statistically by Pearson's chi-square test, with 5% of significance. The first and second molars presented three roots in 99.14% and 87.27% of the cases, respectively. In relation to the number of canals, the first and second molars had a significantly higher frequency of three and four root canals respectively, presenting a higher prevalence of types I and II (p < 0.001). The second mesiobuccal canal (MB2) was observed in 48.21% and 22.72% of the first and second molars, respectively (p < 0.001). The identification of the MB2 canal was greater in young and adult patients (p < 0.001), presenting a higher prevalence in male patients (p < 0.001). The internal configuration of the MB root was influenced by gender and by age, presenting a higher prevalence of the MB2 in male patients younger than 50 years of age.

Comparative Evaluation of Fractal Dimensions of CBCT Images Obtained with i-CAT Next Generation and PreXion 3D Elite Scanners

Comparing Cone-Beam Computed Tomography (CBCT) exams with different fields of view (FOV) are relevant to understand the impact of the inherent image quality on the reliability and accuracy of the diagnostic outcome. This study aimed to comparatively evaluate the results of the fractal analysis of images of the same structure taken in two cone beam computerized scanners with different FOVs. The initial selection of the images used, from two CBCT of the same individual jaw performed in two different scanners, was conducted in the Radiant program (RadiAnt DICOM Viewer) and exported to DICOM format. The selected images were processed in the ImageJ software (US National Institutes of Health), correcting the rotation of the images before conducting fractal analysis. In order to verify the normality of the data, the Shapiro-Wilk test was applied. The Mann-Whitney U, Levene and T tests were applied in order to compare the fractal analysis obtained by the two CBCT scanners. The intraclass correlation coefficient result was 0.988. The mean of the samples in the three comparisons (mentum samples, mental foramen samples and all included mentum and mental foramen samples) was higher for the PreXion 3D scanner. The p value of the tests was 0.000, for the three comparisons, at a 5% confidence level. The comparison of the fractal dimension averages of the images obtained with i-CAT and PreXion 3D scanners showed statistically significant differences, and higher averages were observed in the fractal analysis of images from PreXion 3D scanner. These results point to the need for a careful analysis of the parameters involved in the acquisition of images when results of fractal analysis resulting from different equipment are compared.

Detection of Incomplete Root Fractures in Endodontically Treated Teeth Using Different High-resolution Cone-beam Computed Tomographic Imaging Protocols

IntroductionThe purpose of this study was to compare different high-resolution cone-beam computed tomographic (CBCT) imaging protocols in the diagnosis of incomplete root fractures of endodontically treated teeth. MethodsTwenty single-rooted human teeth were endodontically treated, and an incomplete root fracture was induced. The teeth were scanned with the CBCT unit PreXion 3D (Teracom, San Mateo, CA) operating at 2 different protocols: high resolution/standard (HI-STD) (19 seconds and 512 basis images) and high resolution/high density (HI-HI) (37 seconds and 1024 basis images). Three oral radiologists evaluated all images using multiplanar reconstructions. The diagnostic tests and the receiver operating characteristic (ROC) curve were calculated. ResultsThe HI-STD and HI-HI protocols presented an accuracy of 0.90 and 0.93, respectively, and both protocols had a sensitivity of 0.97. The HI-HI protocol showed a higher positive predictive value and slightly higher areas under the ROC curve. ConclusionsBoth high-resolution imaging protocols presented high accuracy in the detection of incomplete root fracture of endodontically teeth. Thus, the HI-STD protocol should be indicated this reduces the radiation dose.

Intraobserver and interobserver reproducibility in linear measurements on axial images obtained by cone-beam computed tomography.

PurposeThis study was performed to investigate the intra- and inter-observer variability in linear measurements with axial images obtained by PreXion (PreXion Inc., San Mateo, USA) and i-CAT (Imaging Sciences International, Xoran Technologies Inc., Hatfield, USA) CBCT scanners, with different voxel sizes.Materials and MethodsA cylindrical object made from nylon with radiopaque markers (phantom) was scanned by i-CAT and PreXion 3D devices. For each axial image, measurements were taken twice in the horizontal (distance A-B) and vertical (distance C-D) directions, randomly, with a one-week interval between measurements, by four oral radiologists with five years or more experience in the use of these measuring tools.ResultsAll of the obtained linear measurements had lower values than those of the phantom. The statistical analysis showed high intra- and inter-observer reliability (p=0.297). Compared to the real measurements, the measurements obtained using the i-CAT device and PreXion tomography, on average, revealed absolute errors ranging from 0.22 to 0.59 mm and from 0.23 to 0.63 mm, respectively.ConclusionIt can be concluded that both scanners are accurate, although the linear measurements are underestimations, with no significant differences between the evaluators.

Influence of Cone-beam Computed Tomographic Scan Mode for Detection of Horizontal Root Fracture

IntroductionThe purpose of the present study was (1) to test the accuracy of a small-volume cone-beam computed tomographic (CBCT) device in detecting horizontal root fractures (HRFs) in teeth with and without an intracanal metallic post (IMP) and (2) to investigate the use of 2 different acquisition protocols of a CBCT device for HRF diagnosis. MethodsForty endodontically treated teeth with and without an IMP were examined using PreXion 3D CBCT scanner (Terarecon, San Mateo, CA) with a 5-cm high and 5-cm diameter cylinder at 0.10-mm voxel reconstruction. Two observers analyzed the samples to determine the presence and location of HRFs. ResultsSensitivity values ranged from 0.40–0.80. The most favorable results were found for the samples with no IMP observed using the protocol of a higher number of x-ray projections (0.70–0.80). Accuracy in the groups with an IMP ranged from 75%–90% in the 1024 x-ray projection protocol (HI-HI group) versus 70%–85% for the same samples examined in the 512 x-ray projection protocol (HI-STD group). Intraobserver agreement ranged from relevant to perfect concordance for both protocols (HI-HI = Kappa: 0.60–1.00 and HI-STD = Kappa: 0.55–0.89). Interobserver agreement ranged from moderate to perfect concordance for both protocols (HI-HI = Kappa: 0.79–0.89 and HI-STD = Kappa: 0.42–0.76). ConclusionsEven though there are statistically significant differences for the protocol with the higher number of x-ray projections, we found high accuracy, sensitivity, sensibility, and intra- and interobserver agreement in detecting HRFs for both Prexion 3D protocols.

Dosimetric evaluation of dental implant planning examinations with cone-beam computed tomography

The aim of this work was to perform a dosimetric evaluation of two cone-beam computed tomography scanners. The study was performed with two scanners: i-CAT classic and PreXion 3D. Air kerma-area product (PKA) was measured for all full-arch dental implant planning protocols. Surface air kerma was also estimated at the region of the eyes, salivary glands and thyroid using thermoluminescence dosemeters positioned on an anthropomorphic phantom. The PKA values for the i-CAT classic ranged from 24 to 180 µGy m(2) and, for the PreXion, from 70 to 138 µGy m(2). The large variation of these values was mainly caused by acquisition time and field of views. The surface air kerma values were from 0.08 to 3.39 mGy at the eyes, 0.50 to 3.96 mGy at the parotids, 0.11 to 2.95 mGy at the submandibular glands and 0.05 to 1.32 mGy at the thyroid. These values are comparable with those found in the literature.