Assessment of the root filling volume in C-shaped root canal on cone-beam CT and micro-CT in relation to nano-CT.

AIM: To assess the observed volume of filled C-shaped root canals from different CBCT and micro-CT having nano-CT as a reference. MATERIALS AND METHODS: Twelve extracted mandibular molars with C-shaped root canals were endodontically treated using Reciproc Blue R25 (VDW GMBH, Munich, Germany) in a reciprocating system and filled with gutta-percha (Dentsply Maillefer) and AH Plus sealer (Dentsply DeTrey, Konstanz, Germany). CBCT scans were performed using 3 units-3D Accuitomo 170 (J. Morita, Kyoto, Japan), ProMax 3D Max (Planmeca, Helsinki, Finland), and NewTom VGi EVO (Cefla QR, Verona, Italy)-at two resolution modes: standard and high. Micro-CT and nano-CT scans were also obtained. The volume of all filled C-shaped root canals was obtained using CTAn software (Bruker, Kontich, Belgium), and the blooming artifact, in relation to nano-CT volume, was calculated. The data were evaluated by the Bland-Altman plots and ANOVA two-way for repeated measures (α = 0.05). RESULTS: All CBCT units and micro-CT showed significantly larger observed volume of root canal filling when compared to nano-CT. The blooming artifact of root canal filling in standard resolution was significantly larger than that in high resolution (p < 0.05) in all CBCT units. CONCLUSIONS: Endodontic filling material with AH Plus sealer causes blooming artifacts in CBCT units and micro-CT. CLINICAL RELEVANCE: Considering the anatomical complexity of C-shaped root canals and the challenges associated with endodontic treatment, CBCT is frequently recommended for follow-up evaluations. However, the presence of endodontic filling material can result in blooming artifacts that may potentially impact the accurate diagnosis of endodontic complications.

Does the administration of meloxicam before head and neck radiotherapy reduce the risk of mandibular osteoradionecrosis? An animal model study.

OBJECTIVE: To assess whether the administration of meloxicam before head and neck radiotherapy reduces the risk of mandibular osteoradionecrosis in rats. MATERIAL AND METHODS: Sixty male Wistar rats were randomly divided into 6 groups (n = 10) according to the meloxicam administration and radiation therapy: control (C), irradiated (I), single dose of meloxicam (M1), single dose of meloxicam and irradiated (M1I), triple dose of meloxicam (M3), triple dose of meloxicam and irradiated (M3I). Meloxicam was administrated (20 mg/kg per dose) 1 h before the radiation therapy (single dose of 20 Gy) and 24 h and 48 h after the radiation therapy for groups with two additional doses. Ten days after the radiation therapy, the three right mandibular molars were extracted from all rats, who were euthanatized after 21 or 35 days (n = 5 per group). The mandibles were assessed by macroscopic evaluation and micro-CT analysis. RESULTS: The right hemimandibles of the irradiated groups revealed macroscopic signs of osteoradionecrosis, and those of the non-irradiated groups revealed complete gingival healing. A significant delay in alveolar socket healing in all irradiated groups was observed in the micro-CT assessment regardless meloxicam treatment. CONCLUSION: The administration of meloxicam before head and neck radiotherapy does not reduce the risk of mandibular osteoradionecrosis when associated to dental extractions. CLINICAL RELEVANCE: Since meloxicam has been shown to be a potential radiation-protective agent, and osteoradionecrosis physiopathology is believed to be related to an inflammatory process, possible interactions are relevant to be investigated.

Misfit detection in implant-supported prostheses of different compositions by periapical radiography and cone beam computed tomography: An in vitro study.

STATEMENT OF PROBLEM: Misfits at the implant-abutment joint (IAJ) can cause the biological and mechanical failure of implant therapy. Standard parallel periapical radiography (PERI) is the method of choice for assessing the fitting of implant-supported prostheses. Although current guidelines do not support the use of cone beam computed tomography (CBCT) solely for misfit detection, CBCT scans can also register misfits as imaging findings. Whether the material used for prostheses manufacturing influences misfit appearance in PERI and CBCT images is unknown. PURPOSE: The purpose of this in vitro study was to assess the influence of the type of prosthesis material on misfit detection at the IAJ by using PERI and CBCT. MATERIAL AND METHODS: Thirty-two implants with an external hexagon connection were placed in dried human mandibles. Implant-supported crowns were manufactured with different materials and allocated to 3 experimental groups: metal-ceramic (MC), titanium abutment veneered with acrylic resin (TIT), and zirconia abutment veneered with glass-ceramic (ZIR). All crowns were installed both with and without a simulated 200-µm-thick gap at the IAJ (n=64) and were assessed by PERI and CBCT scans. Four dentists evaluated the images for the presence or absence of misfit. Statistical analysis included the Kappa test and areas under the receiver operating characteristics curve (Az values) comparisons (α=.05). RESULTS: Kappa values indicated almost perfect intraevaluator and interevaluator reproducibility for PERI and ranged from fair to almost perfect for CBCT. For PERI, Az values were not significantly different among the MC (0.995), TIT (0.997), and ZIR groups (1.000) (P>.05). Regarding CBCT, the Az values found for TIT (0.941) and MC (0.890) were significantly higher than for ZIR (0.762) (P<.05). Az values for PERI were significantly higher than for CBCT (P<.05). CONCLUSIONS: The type of prosthesis material did not influence misfit detection at the IAJ with PERI; however, ZIR had lower diagnostic accuracy than TIT and MC implant-supported crowns with CBCT.

Efficacy of digital radiography for detecting a second mesiobuccal canal adjacent to unfilled or filled canals.

The aim of this study was to assess the diagnostic accuracy of digital periapical radiography for the detection of the second mesiobuccal (MB2) canal when the adjacent canals are unfilled or filled with gutta percha. Forty human maxillary first molars were selected, 20 of which had an MB2 canal. The presence or absence of the MB2 canal was confirmed using microcomputed tomography. Digital periapical radiographs of each tooth were obtained from 3 horizontal angles before and after the adjacent root canals were filled with gutta percha. Three experienced oral radiologists evaluated all images and indicated the presence or absence of the MB2 canal using a confidence scale of 5 points. To assess intraobserver and interobserver agreement, weighted kappa coefficients were calculated. The diagnostic test (sensitivity, specificity, and accuracy) and area under the receiver operating characteristic curve (Az) values were calculated and compared between groups (n = 40): radiographs of the first molars with unfilled adjacent canals and radiographs of the same teeth with filled adjacent canals. For all observers, intraobserver reproducibility ranged from substantial (0.70) to almost perfect (0.86), and interobserver reproducibility ranged from fair (0.39) to substantial (0.67). Similar values of specificity and Az for the detection of the MB2 canal were observed with unfilled and filled adjacent canals. The sensitivity and accuracy were slightly greater when the adjacent root canals were filled with gutta percha. Detection of the MB2 canal on digital periapical radiographs can be challenging even when obtained at varying horizontal angles, and the presence of gutta percha does not influence the detection.

Retrospective assessment of dental implant-related perforations of relevant anatomical structures and inadequate spacing between implants/teeth using cone-beam computed tomography.

OBJECTIVES: To assess the prevalence of dental implant-related perforations of relevant anatomical structures and inadequate spacing between the implant and the adjacent tooth or implant, and their association with anatomical location, implant dimension, thread exposure, and presence of graft, using cone beam computed tomography (CBCT). MATERIALS AND METHODS: CBCT scans of patients with implants were retrospectively assessed regarding the presence of implant-related perforation of adjacent anatomical structures, and inadequate mesial and distal spacing between the implant and the adjacent tooth/implant (i.e., < 1 mm or < 3 mm, respectively). Implants were classified according to anatomical location, dimensions, thread exposure, and the presence of graft (i.e., bone graft or bone substitutes). Prevalence of perforations and inadequate spacing was compared among the different implant classifications (Chi-squared test). Significance level was set at 5%. RESULTS: A total of 1109 implants were assessed, out of which 369 (33.3%) presented perforation of adjacent structures. Prevalence of perforations in the maxilla (43.5%) was higher than in the mandible (11.3%). Inadequate spacing was found in 18.2% of the mesial and distal measurements, which was more prevalent in the maxilla (p < 0.001). Implants perforating adjacent structures or placed with inadequate spacing presented higher prevalence of thread exposure (p < 0.001). No significant difference was found between the presence of perforations or inadequate spacing and presence of graft (p > 0.05). CONCLUSIONS: Implant-related perforations of relevant anatomical structures and inadequate spacing between the implant and the adjacent tooth/implant are relatively prevalent and more common in the maxilla. Both are associated with threads exposure. CLINICAL RELEVANCE: Information on dental implant-related perforations and inadequate spacing can assist dental surgeons in pre-surgical planning.

A modified protocol of mandibular osteoradionecrosis induction in rats with external beam radiation therapy.

OBJECTIVE: To propose a modified protocol of mandibular osteoradionecrosis induction in rats with external beam radiation therapy. MATERIAL AND METHODS: A total of 45 male Wistar rats were used in this study. Firstly, 25 rats were divided into 5 groups (n = 5) according to the radiation dose protocol: without irradiation and irradiated with 15 Gy, 20 Gy, 25 Gy, or 30 Gy using a linear accelerator. Secondly, 15 other rats were divided into 3 groups (n = 5) according to the time of extraction of the three right mandibular molars: 7, 10, or 14 days after irradiation of 20 Gy. Lastly, dental extractions were performed in 5 other rats without irradiation (C-E10) for comparison with those of the group of dental extractions 10 days after irradiation (I-E10). RESULTS: The irradiated animals survived throughout the study period only at single doses of 15 Gy and 20 Gy. The suitable time for dental extractions after irradiation to induce mandibular osteoradionecrosis was defined as 10 days. Macroscopic evaluation of the right hemimandibles showed presence of osteoradionecrosis in I-E10 group and complete gingival healing in C-E10 group. CONCLUSION: A single radiation dose of 20 Gy focused on head and neck region combined with the extraction of the three mandibular molars 10 days after irradiation constitutes a feasible protocol of mandibular osteoradionecrosis induction in rats with external beam radiation therapy. CLINICAL RELEVANCE: Establishing a solid and widely available protocol of mandibular osteoradionecrosis induction is essential in the search for methods to prevent this complex disease.

Assessment of dentists' behaviour on the use of patients' images.

BACKGROUND: Photographs and radiographs are indispensable resources for dental education, research and dissemination of clinical cases in scientific journals. The objective of this study was to evaluate the behaviour of dentists on the use of patients' images. MATERIAL AND METHODS: Fifty-two dentists were interviewed using a semi-structured script containing open-ended questions on the use of patients' images. The answers were analysed using a qualitative-quantitative method of the discourse of the collective subject, and the distribution of the absolute and relative frequency of the answers was presented according to the central ideas obtained from the discourses. RESULTS: The following central ideas on the use of patients' images were identified: (a) purpose: didactic and/or academic; (b) informed consent: verbal or absent when the patient cannot be identified; (c) discussion groups on social media contribute to learning; (d) most dentists would not appreciate and sue the author if they had their own photographs/imaging examinations posted on social media; 5. most dentists received some information on ethical regulations during dental school and state that images can be used with patient authorisation, without identification and for didactic/academic purposes. CONCLUSION: Dentists consider the use of patients' images for didactic and scientific purposes beneficial, request informed consent to share mainly images that reveal the identity and would not appreciate if their personal images were shared without consent.

Validity of an Inexpensive Hanging Scale During Isometric Shoulder Movements.

CONTEXT: Strength assessment is essential to prescribe exercise in sports and rehabilitation. Low-cost valid equipment may allow continuous monitoring of training. OBJECTIVE: To examine the validity of a very low-cost hanging scale by comparing differences in the measures of peak force to a laboratory grade load cell during shoulder abduction, flexion, extension, and internal and external rotations. DESIGN: Analytical study. PARTICIPANTS: Thirty-two healthy subjects (18 women, age 26 [10] y, height 172 [8] cm, mass 69 [13] kg, body mass index 23 [4] kg/m2). MAIN OUTCOME MEASURES: The dependent variable was the maximal peak force (in kilogram-force). The independent variable was the instrument (laboratory grade load cell and hanging scale). RESULTS: No differences were observed while comparing the results. The intraclass correlation coefficients1,1 ranged from .96 to .99, showing excellent results. The Cronbach alpha test also returned >.99 for all comparisons. The SEM ranged from 0.02 to 0.04 kgf, with an averaged SD from 0.24 to 0.38 kgf. The correlation was classified as high for all tested movements (r > .99; P < .001), with excellent adjusted coefficients of determination (.96 < r2 < .99). Bland-Altman results showed high levels of agreement with bias ranging from 0.27 to 0.48. CONCLUSIONS: Hanging scale provides valid measures of isometric strength with similar output measures as laboratory grade load cell.

Brightness and contrast adjustments influence the radiographic detection of soft tissue calcification.

OBJECTIVE: To assess the influence of subjective enhancement of brightness and contrast of digital panoramic radiographs on the detection of soft tissue calcifications. MATERIALS AND METHODS: In this observational study, 500 digital panoramic radiographs were evaluated by two examiners in consensus, who scored the images for the presence of calcifications for each right and left side of the image. After 30 days, all images were revaluated under subjective manipulation of digital brightness and contrast. Calcifications were classified based on the diagnostic hypothesis: sialolith, tonsillolith, calcified atheroma, phlebolith, rhinolith, maxillary sinus antrolith, synovial chondromatosis, lymph node calcification, stylohyoid ligament, triticeous cartilage, or/and upper horn of thyroid cartilage calcification. For intra-examiner agreement, 20% of the sample was reevaluated. The Kappa test and McNemar test were used (α = 0.05). RESULTS: In original images, calcifications were observed in 44.2% of the patients, and in enhanced images, this number was 70.8%. Many calcifications were detected only in enhanced images, mainly in the diagnostic hypotheses of calcified atheroma and stylohyoid ligament. Intra-examiner agreement was excellent for the detection of soft tissue calcifications (0.82) and for the classification (0.81). CONCLUSION: Subjective enhancement of brightness and contrast alters the detection of soft tissue calcifications in digital panoramic radiograph.

Morphological Evaluation of the Nasopalatine Canal in Patients With Different Facial Profiles and Ages.

PURPOSE: To evaluate the influence of facial profile and age on the morphology of the nasopalatine canal. MATERIALS AND METHODS: One hundred thirty-two cone-beam computed tomograms were classified according to facial profile-mesofacial, brachyfacial, and dolichofacial-and divided into the following age groups: 21 to 30, 31 to 40, 41 to 50, and 51 to 60 years. Measurements were obtained for openings of the incisive and nasopalatine foramina, alveolar bone thickness, and the full length, most constricted region, and volume of the nasopalatine canal. Intra- and inter-examiner agreements were calculated using the intraclass correlation coefficient. After exploratory and descriptive analysis, data were subjected to 2-way analysis of variance and Tukey test for comparisons between facial profiles and age groups. The significance level was 5% (α = 0.05). RESULTS: Intra- and inter-examiner reproducibilities were excellent for all measurements. Patients older than 50 years presented a significantly larger nasopalatine canal than patients 21 to 30 years old for all facial profiles (P ≤ .05). Linear measurements obtained from the nasopalatine canal showed no significant difference between facial profiles and age groups (P > .05). CONCLUSIONS: The nasopalatine canal was not influenced by facial profile but did exhibit an increased volume with aging, particularly after 50 years of age.

Evaluation of metal artefact reduction in cone-beam computed tomography images of different dental materials.

OBJECTIVE: The aim of this study is to evaluate the efficacy of metal artefact reduction (MAR) in different dental materials with Picasso Trio cone-beam computed tomography (CBCT) scanner. MATERIALS AND METHODS: Three imaging phantoms were custom-made of acrylic resin. Each phantom presented three cylinders of the same material: dental amalgam alloy, gutta-percha or aluminium-copper alloy. CBCT scans were performed on Picasso Trio unit with and without MAR, and artefact expression (standard deviation of grey values) was obtained and compared by Kruskal-Wallis and Student-Newman-Keuls (post hoc) (α = 0.05). RESULTS: Significant reduction of artefact expression (p < 0.05) was observed with MAR on areas around dental alloys. No significant difference (p > 0.05) was observed with or without MAR when gutta-percha was scanned. CONCLUSION: MAR was effective in reducing artefacts arising from dental alloys on CBCT images. CLINICAL RELEVANCE: Dental materials of high atomic number and density are widely used in dentistry and can produce artefact that compromise CBCT image. The present study demonstrated that metal artefact reduction algorithm is an effective tool to improve image quality.

Clinical implications, diagnosis, and treatment of a giant frontoethmoid osteoma.

Osteomas are benign, asymptomatic fibro-osseous tumors that are most commonly observed in the paranasal sinuses and sometimes are found in imaging examinations that were taken for other reasons. Giant osteomas are rarely found in the frontal and ethmoid sinuses but, when they are, they may cause intracranial and orbital complications. The aims of this case report are to describe a frontoethmoid osteoma in a 40-year-old woman, discuss the characteristics of this lesion through cone beam computed tomography (CBCT) imaging, and review the options for treatment. A CBCT examination performed for the purpose of orthodontic diagnosis revealed the presence of a large, well-defined, lobular, hyperdense mass that occupied a sizeable area of the frontal sinus and extended to the ethmoid sinus. The patient did not report any pain. Based on the physical and imaging characteristics of the mass, the location and size of the lesion, and the patient's age, the diagnosis was a giant frontoethmoid osteoma. Due to its enhanced field of view, CBCT may enable earlier diagnosis of lesions that affect the maxillofacial region.

Diagnostic accuracy of phosphor plate systems and conventional radiography in the detection of simulated internal root resorption.

OBJECTIVE: To evaluate the performance of conventional radiography and photostimulable phosphor (PSP) plate in the detection of simulated internal root resorption (IRR) lesions in early stages. MATERIALS AND METHODS: Twenty single-rooted teeth were X-rayed before and after having a simulated IRR early lesion. Three imaging systems were used: Kodak InSight dental film and two PSPs digital systems, Digora Optime and VistaScan. The digital images were displayed on a 20.1″ LCD monitor using the native software of each system, and the conventional radiographs were evaluated on a masked light box. Two radiologists were asked to indicate the presence or absence of IRR and, after two weeks, all images were re-evaluated. Cohen's kappa coefficient was calculated to assess intra- and interobserver agreement. The three imaging systems were compared using the Kruskal-Wallis test. RESULTS: For interexaminer agreement, overall kappa values were 0.70, 0.65 and 0.70 for conventional film, Digora Optima and VistaScan, respectively. Both the conventional and digital radiography presented low sensitivity, specificity, accuracy, positive and negative predictive values with no significant difference between imaging systems (p = .0725). CONCLUSIONS: The performance of conventional and PSP was similar in the detection of simulated IRR lesions in early stages with low accuracy.

Concrescence: assessment of case by periapical radiography, cone beam computed tomography and micro-computed tomography.

The aim of this article was to describe imaging aspects of concrescence analyzed by three imaging modalities. A second molar joined together with a third molar was imaged using digital periapical radiography, cone beam computed tomography (CBCT) and micro-computed tomography (Micro-CT). On periapical radiograph, the mesial root of the third molar is superimposed on the distal root of the second molar. On CBCT images, a large cementum union between bulbous roots was detected, confirming the diagnosis of concrescence. On micro-CT images, the cementum union appeared limited to the apical third of the roots. In conclusion, both computed tomography modalities allowed for the diagnosis of concrescence. However, only micro-CT provided the real extension of the cementum union.

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

OBJECTIVES: The 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 METHODS: Seventy-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. RESULTS: FD 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. CONCLUSIONS: The mandibular trabecular bone was effective in detecting osteoporotic changes, with the exception of the right mandibular body. CLINICAL RELEVANCE: Mandibular 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 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.

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.

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.

Objective assessment of the combined effect of exomass-related- and motion artefacts in cone beam CT.

OBJECTIVES: To assess quantitatively the combined effect of exomass-related- and motion artefacts on voxel value parameters in cone beam CT (CBCT). METHODS: A cylindrical phantom was manufactured, containing 21 tubes filled with a radiopaque solution, allowing the inclusion of three titanium implants in the periphery to induce exomass-related artefacts. The phantom was mounted on a robot simulating 0.75-, 1.5-, and 3 mm movements (nodding/lateral rotation/tremor). CBCT images with/without exomass and with/without movements were acquired in duplicate in three units: Cranex 3Dx, Orthophos SL-3D, and X1 (with motion-artefact correction). A cylindrical volume of interest was defined in each tube and voxel value mean and standard deviation were assessed. For each CBCT volume, the 21 mean voxel values were averaged providing the overall mean voxel value (MVV), and the standard deviation (among the 21 values) was calculated providing overall voxel value inhomogeneity (VVI). The standard deviation from each of the 21 volumes-of-interest were averaged, providing overall image noise (IN). The effect of the diverse tested situations was inferred from a repeated-measures analysis of variance, followed by Sidak's test (α = 0.05). RESULTS: Overall, images acquired with exomass showed significantly (p ≤ 0.05) lower MVV, and higher VVI and IN. Motion artefacts aggravated exomass-related alterations. MVV and VVI were mostly affected by 3 mm nodding movements. Motion-artefact correction eliminated the deleterious effect of movement. CONCLUSIONS: CBCT voxel-value parameters are altered by exomass-related artefacts, and this finding is aggravated in the presence of motion artefacts. Motion-artefact correction effectively eliminated the deleterious impact of movement.

Influence of the exomass on the detection of simulated root fracture in cone-beam CT - an ex-vivo study.

OBJECTIVES: To evaluate the influence of exomass-related metal artefacts on the detection of simulated vertical root fracture (VRF) in cone-beam computed tomography (CBCT). METHODS: 20 teeth were endodontically instrumented and VRF was induced in half of them. All teeth were individually placed in an empty socket of a human mandible. Metallic materials were differently arranged in the exomass [zone outside of the field of view (FOV) but between the X-ray source and the receptor] and/or endomass (zone inside of the FOV), and CBCT scans were obtained. Four radiologists evaluated the presence of VRF using a 5-point scale. Sensitivity, specificity, and area under the receiver operating curve (AUC) were compared using ANOVA. Also, the tooth of interest was replaced with a tube filled with a radiopaque solution and all CBCT scans were repeated to analyse the data objectively. Mean grey and noise values were obtained from the tube and compared using ANOVA followed by Tukey's test (α = 0.05). RESULTS: Mean grey values were significantly lower and noise was significantly higher when metallic materials were present in the endomass or both the exomass and endomass. Sensitivity, specificity, and AUC were not influenced by the artefacts from the metallic materials irrespective of the arrangement condition. CONCLUSIONS: Exomass-related metal artefacts did not influence the diagnosis of simulated VRF in CBCT.