Root Curvature in Non-Syndromic Oral Clefts: A Case-Control Study in a Brazilian Population

OBJECTIVE

This study assesses the degree of root curvature in patients with non-syndromic cleft lip and/or palate (NSCL/P).

DESIGN

Retrospective. Case-control study.

SETTING

Root curvature was assessed in lower premolars and molars in 800 panoramic radiographs: 400 from patients with cleft and 400 from healthy control individuals. Root curvature was classified according to its angulation, as well as its apical, medial, or coronal localization.

RESULTS

The frequency of mild curvature in the NSCL/P group compared to the control group was higher in premolars especially in the left second premolar in cleft palate (OR: 6.91; 95% CI: 3.23-14.77; P < .0001). The frequency of moderate curvature in molars was significantly higher in the cleft group, with the highest risk in the right first molar in the cleft lip group (OR: 2.74; 95% CI: 1.67-4.52; P < .0001). Inclination was more frequently observed in the apical third of the root in the group with cleft, whereas for the control group, the curvature was more frequent in the medial third. In patients with cleft, the OR of curvature in the apical third was significant in premolars (left lower second premolar: Cleft lip, OR: 1.91; 95% CI: 1.04-3.52; P = .03; right lower second premolar: Cleft lip, OR: 1.91, 95% CI: 1.04-3.50; P = .03, cleft lip and palate, OR: 1.75; 95% CI: 1.12-2.73; P = .01).

CONCLUSION

The results of the current study indicate differences in root curvature in patients with non-syndromic cleft lip and/or palate, which should be considered during the dental treatment planning of patients.

Ambient light exposure of photostimulable phosphor plates: is there a safe limit for acceptable image quality?

OBJECTIVES

To subjectively assess radiographs obtained with photostimulable phosphor (PSP) plates exposed to clinical levels of ambient light prior to read-out to potentially set a safe limit for acceptable image quality.

METHODS AND MATERIALS

Six dental regions of a dry human skull were X-rayed using PSP plates from VistaScan and Express under four exposure times: 0.1, 0.2, 0.32, and 0.4 s. Before read-out, the PSP plates were exposed to ambient light for 0, 5, 10, 30, 60, and 90 s. Six observers were asked to classify the 288 resulting radiographs as acceptable or unacceptable based on the identification of anatomical structures and global image quality. The number of answers classifying radiographs as unacceptable was used to calculate a rejection rate; a pairwise comparison for better image quality was further conducted among radiographs considered acceptable. Reproducibility was tested by having 25% of all experimental groups reassessed.

RESULTS

Intra- and interobserver agreement ranged from 0.87 to 1.00 and from 0.81 to 0.92, respectively. Exposure of PSP plates to ambient light increased rejection rates mostly as of 10 s. In the pairwise comparison, subtle differences were observed between radiographs obtained with PSP plates not exposed and those exposed to ambient light for 5 s.

CONCLUSIONS

Ambient light exposure of PSP plates impairs the image quality of radiographs. A safe limit of ambient light exposure of 5 s for VistaScan and Express should be considered. Ambient light exposure of PSP plates within safe limits can avoid retakes and reduce unnecessary patient exposure to X-rays.

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.

Can the detection of second mesiobuccal canals be enhanced based on the volume of adjacent canals?

OBJECTIVES

The purpose of this study was to evaluate whether the presence of the second mesiobuccal (MB2) canal is related to volumetric differences on the adjacent canals of maxillary molars.

DESIGN

Forty-seven maxillary first and second molars with and without the MB2 canal were individually scanned using microcomputed tomography (micro-CT). The volume of each canal was measured by an evaluator with experience in micro-CT analysis. The intraclass correlation coefficient (ICC) was obtained. Multiple logistic regression and odds ratio was calculated. To compare the volume of canals in molars with and without MB2, the Mann-Whitney test was applied (α = 0.05).

RESULTS

The intra-examiner reproducibility was almost perfect (ICC=0.97). Multiple logistic regression demonstrated that the volume of the mesiobuccal (MB1) canal can possibly act as a predictor of the presence of the MB2 canal. It was also found that the MB1 canal volume is larger in molars without the MB2 canal (p = 0.01). No statistically significant difference was observed in the adjacent canals (p > 0.05).

CONCLUSIONS

Despite the challenging detection of the presence of MB2 canals, clinicians should be aware that MB1 canals of reduced volume are highly suggestive of their presence.

Influence of metal artefact reduction tool on the detection of vertical root fractures involving teeth with intracanal materials in cone beam computed tomography images: A systematic review and meta-analysis

BACKGROUND

The effectiveness of the metal artefact reduction (MAR) tool for the detection of vertical root fracture (VRF) by cone beam computed tomography (CBCT) images is controversial.

OBJECTIVE

To evaluate the effectiveness of the MAR tool on VRF detection involving teeth with intracanal materials in CBCT images.

METHODOLOGY

In September 2019, an electronic search was performed in six databases (PubMed, Scopus, Web of Science, Cochrane, Lilacs and Embase). The electronic search was updated in May 2020 through searches in Google Scholar and references of included studies (embracing the electronic and gray literature searches). No language or year restrictions were applied. Independently, two reviewers examined titles, abstracts and full texts according to the eligibility criteria that were as follows: diagnostic studies that evaluated the effectiveness of the MAR tool on the diagnosis of VRF in human teeth (laboratory or in vivo studies) on CBCT images. The risk of bias was evaluated using the Quality Assessment Tool for Diagnostic of Accuracy Studies-2 (QUADAS-2). For conducting the meta-analysis, the values of sensitivity, specificity, diagnostic odds ratio (DOR) and area under the ROC curve (AUC) were obtained, considering the subgroups with and without MAR active. The Grading of Recommendation, Assessment, Development and Evaluation instrument was applied to assess the level of evidence across the studies using GRADEpro software.

RESULTS

A total of 8 laboratory studies were included in both systematic review and meta-analysis. The values of sensitivity, specificity, DOR and AUC to VRF diagnosis with and without MAR active were, respectively, 0.586 and 0.603; 0.699 and 0.713, 3.037 and 3.767; 0.67 and 0.71. The quality of the evidence suggested low confidence in estimating the outcomes.

DISCUSSION

The MAR tool decreased slightly the diagnostic values of VRF involving teeth with intracanal materials in laboratory studies. However, it is important to highlight that most studies had an uncertain risk of bias.

CONCLUSIONS

Although a low level of evidence and high heterogeneity were observed in the included studies, the meta-analysis revealed better diagnosis values for VRF detection when the MAR was deactivated when analysing extracted teeth in a laboratory setting.

REGISTRATION

PROSPERO-CRD42020145222.

FUNDING

This study was financed in party by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior-Brasil (CAPES).

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.

Do the tube current and metal artifact reduction influence the diagnosis of vertical root fracture in a tooth positioned in the vicinity of a zirconium implant? A CBCT study

AIM

To evaluate the influence of the tube current and metal artifact reduction (MAR) tool on the diagnosis of vertical root fractures (VRF) in a tooth adjacent to a zirconium implant, in cone-beam computed tomography (CBCT) images.

METHODOLOGY

Thirty single-rooted teeth (15 with VRF and 15 control group) were individually positioned in a mandible, and scanned with the OP300 CBCT unit. Images were acquired using a standardized protocol: 5 × 5 cm field of view, 0.08-mm voxel size, and 90 kVp. Each tooth was scanned with and without a zirconium implant in its vicinity, using different tube currents (4 mA, 8 mA, and 10 mA) and conditions of MAR (enabled × disabled). Diagnostic values were calculated for each protocol, and compared by multi-way analysis of variance.

RESULTS

The ROC curve and sensitivity values did not differ significantly among the tube currents, regardless of the presence of the implant and MAR condition (p > 0.05). There were also no significant differences among the tube currents for the specificity values (p > 0.05); however, the specificity differed significantly between the "with implant" and "without implant" conditions, within the same MAR condition and tube current (p < 0.05). Specificity was significantly lower when the implant was present (p < 0.05).

CONCLUSION

The presence of a zirconium implant impairs the diagnosis of VRF in teeth adjacent to the artifact-generator material. Neither the tube current nor the MAR tool is effective in improving this diagnostic task. Therefore, in this clinical scenario, the use of the lowest tube current (4 mA), without MAR activation, is recommended.

CLINICAL RELEVANCE

Considering that the tube current is one of the main factors that influence the radiation dose and image quality in CBCT, and that metal artifacts negatively influence the diagnosis of VRF in areas adjacent to the artifact-generator material, it is important to evaluate the effect of this energetic parameter in the diagnosis of VRF in teeth adjacent to zirconium implants.

Mapping the expression of beam hardening artefacts produced by metal posts positioned in different regions of the dental arch

OBJECTIVES

To objectively assess the expression and direction of artefacts in the vicinity of metal posts positioned in different mandibular regions.

MATERIALS AND METHODS

A human mandible had two sockets prepared-anterior and posterior regions-to accommodate a single-rooted tooth. Two CBCT units, Picasso Trio and OP300, were used. CBCT images of the tooth without metal post, and with silver-palladium, nickel-chromium, or cobalt-chromium posts (experimental groups) were individually acquired. Then, 8 lines of interest (LOIs) were determined around the root canal, in an axial reconstruction: 4 in orthogonal (buccal, lingual, mesial, and distal) directions, and 4 in oblique (mesiobuccal, distobuccal, mesiolingual, and distolingual) directions. The mean of gray values was measured for each LOI.

RESULTS

For the OP300, in general, all experimental groups showed greater expression of hyperdense streaks in orthogonal LOIs and greater expression of hypodense streaks in oblique LOIs. For the Picasso Trio, for both mandibular regions, the buccal LOI showed greater expression of hypodense streaks; conversely, greater expression of hyperdense streaks was observed in the distal and distobuccal LOIs in the anterior region and in the mesiolingual LOI in the posterior region. The silver-palladium group showed significantly greater expression of beam hardening artefacts in the posterior region of the mandible, regardless of the CBCT unit (p < 0.05). The mandibular posterior region showed significantly lower gray values than the anterior region (p < 0.05).

CONCLUSION

The expression and direction of artefacts produced in the vicinity of metal posts vary according to the mandibular region, composition of the post, and CBCT unit.

CLINICAL RELEVANCE

The mapping of artefacts produced by metal posts reveals the root regions with greater expression of hypodense and hyperdense artefacts, which may contribute to recognizing regions more likely to mimic or hide root fracture lines.

Does the metal artifact reduction algorithm activation mode influence the magnitude of artifacts in CBCT images?

Purpose

This study was conducted to assess the effectiveness of a metal artifact reduction (MAR) algorithm activated at different times during cone-beam computed tomography (CBCT) acquisition on the magnitude of artifacts generated by a zirconium implant.

Materials and Methods

Volumes were obtained with and without a zirconium implant in a human mandible, using the OP300 Maxio unit. Three modes were tested: without MAR, with MAR activated after acquisition, and with MAR activated before acquisition. Artifacts were assessed in terms of the standard deviation (SD) of gray values and the contrast-to-noise ratio (CNR) in 6 regions of interest with different distances (10 to 35 mm, from the nearest to the farthest) and angulations (70° to 135°) from the implant region.

Results

In the acquisitions without MAR, the regions closer to the implant (10 and 15 mm) had a higher SD and lower CNR than the farther regions. When MAR was activated (before or after), SD values did not differ among the regions (P>0.05). The region closest to the implant presented a significantly lower CNR in the acquisitions without MAR than when MAR was activated after the acquisition; however, activating MAR before the acquisition did not yield significant differences from either of the other conditions.

Conclusion

Both modes of MAR activation were effective in decreasing the magnitude of CBCT artifacts, especially when the effects of the artifacts were more noticeable.

Age and sex estimation based on pulp cavity volume using cone beam computed tomography: development and validation of formulas in a Brazilian sample

OBJECTIVES

To develop and validate formulas for age and sex estimation based on the pulp cavity volume of teeth using cone beam CT.

METHODS

The sample was composed of 116 cone beam CT scans from Brazilian individuals of both sexes, ranging in age from 13 to 70 years. A total of 232 teeth (upper central incisors and canines) were evaluated. Two calibrated examiners determined pulp cavity volumes using the ITK-SNAP software. Pearson's correlation test was used to assess the correlation between chronological age and pulp volume. Linear and logistic regression models were developed for age and sex estimation, respectively, and were validated in another sample of 72 teeth.

RESULTS

Pearson's correlation coefficients between age and pulp volume were negative and significant (p < 0.0001) for both teeth (r = -0.8782 for central incisors and r = -0.8738 for canines). The age estimation formulas showed good determination coefficients (adjusted R² = 0.7614 to 0.8367). For sex estimation, when the age was known, the coefficients were also good (adjusted R² = 0.649 to 0.812). However, when the age was unknown, the coefficients of the sex estimation formulas were low (adjusted R² = 0.047 to 0.393). Validation showed high accuracy of age estimation in individuals older than 35 years, as well as high accuracy of sex estimation when the age was known.

CONCLUSIONS

Our formulas provided excellent results and can be applied to the Brazilian population. The best results were observed for age estimation in females and for sex estimation when the age was known.

Root canal configuration and its relation with endodontic technical errors in premolar teeth: a CBCT analysis

AIM

To evaluate the association between endodontic technical errors and the root canal configuration (RCC) of human premolars, as well as their relationship with periapical lesions through cone-beam computed tomography (CBCT) images.

METHODOLOGY

The sample consisted of CBCT scans belonging to 136 patients, totalling 152 root filled premolars (185 roots). CBCT images were evaluated by two oral radiologists. RCC was recorded according to Vertucci's classification, and the endodontic treatment quality was judged on the presence and type of technical endodontic errors (underfilling, overfilling, nonhomogeneous filling, nonfilled canal, fractured instruments, root deviation and absence of coronal restoration). In addition, the presence of periapical lesions associated with each RCC was recorded. Data were expressed by frequencies and percentages, and intraobserver agreement was calculated using the Kappa test.

RESULTS

The most common RCC was type I (71%), followed by type IV (15%), type II (8%), type V (3%), type VI (1%) and type III (1%). Types VII and VIII were not observed in the sample. Underfilling was the most frequent endodontic technical error for most RCCs, except for types IV, V and 'other', whose most frequent error was a nonfilled canal. The presence of technical errors was greater with an increase in the proportion of the periapical lesions. The intraobserver agreement was excellent.

CONCLUSIONS

There was an increase in the prevalence of endodontic technical errors and in the presence of periapical lesions as the anatomical complexity of the root canals increased. Underfilled and nonfilled canal were the most frequent endodontic technical errors.

Diagnosis of external root resorption in teeth close and distant to zirconium implants: influence of acquisition parameters and artefacts produced during cone beam computed tomography

AIM

To assess the influence of artefacts, the metal artefact reduction (MAR) tool and kilovoltage (kVp) on the diagnosis of simulated external root resorption (ERR) in teeth close and distant to zirconium implants in cone beam computed tomography (CBCT) images.

METHODOLOGY

Cavities (0.62 mm in diameter and 0.19 mm deep) were created in the apical thirds of 12 roots on the buccal, lingual, distal or mesial surface; ten roots served as controls. The roots were randomly positioned in the first and second right and left premolar sockets of a dry human mandible, and a zirconium implant was placed in the socket of the first right molar. A ProMax 3D unit varying kVp (70, 80, or 90 kVp) and with the MAR tool activated or not was used to obtain CBCT scans. Five examiners evaluated all images to determine the area under the receiver operating characteristic (ROC) curve, sensitivity and specificity.

RESULTS

The ROC values and sensitivity were not affected by MAR or artefacts regardless of the distance to the implant (P > 0.05), whilst increasing kVp from 70 to 90 led to a significant increase in these values (P = 0.0202 and 0.0199, respectively). Specificity was not affected by the factors studied (P > 0.05).

CONCLUSIONS

Amongst the factors studied, only kVp influenced the diagnosis of simulated external root resorption in CBCT images. Increasing kVp from 70 to 90 improved the accuracy in diagnosing the simulated lesions.

Correlation between temporomandibular joint temporal component pneumatization and morphology: analysis by cone beam computed tomography

The aim of this study was to evaluate whether a correlation exists between temporal bone pneumatization and the morphology of the articular eminence and glenoid fossa. A sample of 100 cone beam computed tomography scans was used, for a total of 200 temporomandibular joints (TMJ). Paracoronal and parasagittal images of the TMJ were evaluated by two examiners. For all TMJ, pneumatization was classified in the mid-lateral direction using a score of 0 or 1, and in the anteroposterior direction using a score ranging from 0 to 3. The inclination and height of the articular eminence and the thickness of the roof of the glenoid fossa were obtained. Pneumatization was found in the mid-lateral direction in 83.5% of the cases and in the anteroposterior direction in 88%. The age of the patient and side did not influence the prevalence or degree of pneumatization (P=0.051-0.953), but female patients showed more pneumatization in the mid-lateral direction than male patients (P=0.014). The presence of pneumatization did not affect articular eminence and mandibular fossa morphology. It is concluded that the presence and extent of pneumatization of the TMJ temporal component does not affect its morphology. However, professionals should be aware of the high prevalence of pneumatization and take this into account when performing TMJ assessment.

Influence of brightness and contrast adjustments on the diagnosis of proximal caries lesions

OBJECTIVES

To assess the influence of brightness and contrast adjustments of digital radiographs on the diagnosis of proximal caries lesions, and to compare with observers' preferences for subjective image quality.

METHODS

80 proximal surfaces of posterior teeth were radiographed using an intraoral digital system (Digora Toto, Soredex, Finland). Initial images and four different combinations of brightness and contrast for each radiography were analysed. Five observers scored the images for the presence and extension of caries lesions. Micro-CT images were used as gold standard. In a second stage, the observers were asked which of the radiographs they preferred for the assessment of caries lesions.

RESULTS

No differences were found between the original and adjusted radiographic images regarding the area under the receiver operating characteristic curve, sensitivity, and specificity (p > 0.05). There was a significant difference between the micro-CT and the intraoral radiographs (p < 0.0001). Images with high brightness and low contrast presented higher number of true negative cases, but also a decrease in caries detection. On the other hand, there were more cases of overestimation of the presence and extension of caries lesions in images with low brightness and high contrast. The subjective evaluation of image quality showed that radiographs with lower brightness and higher contrast tended to be preferred by observers.

CONCLUSIONS

Brightness and contrast adjustments in digital intraoral radiographs within the range tested in this study do not significantly influence the diagnosis of proximal caries lesions, although observers tend to prefer lower brightness and higher contrast images.

Magnitude of cone beam CT image artifacts related to zirconium and titanium implants: impact on image quality

OBJECTIVES

To evaluate the magnitude of artifacts related to titanium and zirconium implants at different distances and angulations and their impact on cone beam CT(CBCT) image quality.

METHODS

CBCT images were obtained before and after the insertion of titanium and zirconium implants in a mandible on different CBCT units: Picasso Trio, ProMax 3D and 3D Accuitomo 80. Artifact was assessed by measuring the standard deviation (SD) of gray values and contrast-to-noise ratio (CNR) of 11 regions of interest (ROIs) at different distances (1.5 cm, 2.5 cm and 3.5 cm) and angulations (65°, 90°, 115° and 140°) from implant region.

RESULTS

For titanium images, SD values did not differ from those of images without implant in all ROIs; however, some effect occurred in Picasso images as higher values were observed in ROIs closer to the implant (p < 0.05). Zirconium images showed higher SD values than the others in some ROIs for Picasso and ProMax (p < 0.05). In ProMax, the difference was observed even in the farthest ROIs from the implant. CNR values were not influenced by the ROI in Picasso, but presented lower values in ROIs closer to the zirconium implant for ProMax and Accuitomo.

CONCLUSIONS

The quantity and magnitude of artifacts in CBCT are influenced by the type of implant and CBCT unit. Although they are more pronounced in regions closer to the implant and located at 90° in relation to the mandibular long axis, they can reach as far as 3.5 cm from the artifact-generator object.

Metallic materials in the exomass impair cone beam CT voxel values

OBJECTIVES

To assess the influence of artefacts arising from metallic materials in the exomass on cone beam CT (CBCT) voxel values.

METHODS

CBCT scans were taken of a phantom composed of 16 tubes filled with a homogeneous hyperdense solution and metallic materials of different compositions (titanium, cobalt-chromium and amalgam) and numbers (one, two and three). The phantom was centred in a 5 × 5 cm field of view such that the metallic materials were located in the exomass, using three CBCT units. Voxel values were obtained from the 16 homogeneous areas and averaged. Also, standard deviation was calculated to measure voxel value variability. Analysis of variance in a factorial scheme with additional treatment 3 × 3 + 3 (material × number + control) was performed, followed by Tukey's test for multiple comparisons, and Dunnett's test for comparisons with the control groups, at a level of significance of 5%.

RESULTS

Metallic material in the exomass significantly reduced the mean voxel value in the CS9300 and Picasso Trio units, and increased voxel value variability in all CBCT units. Amalgam was the material that induced significantly greater reduction of the mean voxel value in the CS9300 and Picasso Trio units, and significantly greater increase in the NewTom Giano. Voxel value variability was significantly greater for amalgam in all conditions. The presence of one cylinder induced significantly less pronounced effects on the mean voxel value and voxel value variability.

CONCLUSIONS

Artefacts arising from metallic materials in the exomass have a negative influence on CBCT voxel values.

Prevalence of soft tissue calcifications in the maxillofacial region detected by cone beam CT

OBJECTIVE

To determine the prevalence of soft tissue calcifications in cone beam computed tomography (CBCT) scans with different fields of view (FOV) and to assess its relation with the clinical relevance of the CBCT findings.

MATERIAL AND METHODS

One thousand CBCT scans were grouped according to FOV's size and region scanned (MX-FOV, maxilla; MD-FOV, mandible; and MM-FOV, maxilla/mandible) and evaluated for the presence of soft tissue calcifications. Laterality and length of the elongated styloid processes (ESP) were also assessed.

RESULTS

Eight hundred and eighty-two soft tissue calcifications were detected in 626 (62.6%) patients. MM-FOV presented the highest prevalence (76.8%), followed by MD-FOV (60.6%) and MX-FOV (57.2%). ESP and tonsillolith were the most frequent calcifications. Calcifications requiring treatment or not and those in need of follow-up accounted for 6.9%, 92.7%, and 0.3% of cases, respectively. There was no association between calcifications and subjects' gender or age (p > .05). Most cases of ESP occurred bilaterally and were longer in males (p < .05).

CONCLUSIONS

There is a high prevalence of soft tissue calcifications in CBCT, and ESP and tonsilloliths are the most common types in all evaluated FOVs. While most cases do not require treatment, we emphasize the importance of detailed CBCT assessment for its diagnosis.

Evaluation of a metal artefact reduction tool on different positions of a metal object in the FOV

OBJECTIVES

To evaluate the action of a metal artefact reduction (MAR) tool when artefact-generator metal object is at different positions in the field of view (FOV).

METHODS

A cylindrical utility wax phantom, with a metal alloy sample inside, was made. The phantom was positioned centrally and peripherally in the FOV for image acquisition, with and without the MAR tool activation. The standard deviation values (image noise levels) from areas around the metal sample and the control area were obtained. The numbers were compared by Student's t-test (α = 0.05).

RESULTS

When the tool was activated, a significant difference of image noise was observed for central and peripheral positioning, for both control area (p = 0.0012) and metal area (p = 0.03), and a smaller level of noise was observed for images with phantoms in central positioning. A decrease in image noise with the tool activated was found only in phantoms with the metal object positioned centrally in the FOV.

CONCLUSIONS

For the MAR tool to be effective, the artefact-generator object needs to be in the central region of the FOV.

Comparison of panoramic radiography and CBCT to identify maxillary posterior roots invading the maxillary sinus

OBJECTIVES

Given the limitations of panoramic radiography for assessing topographic relationship of maxillary teeth with sinus floor, the purpose of this study was to assess signs on panoramic radiography that could predict root protrusion into the sinus.

METHODS

A total of 46 individuals (330 maxillary posterior teeth) who underwent panoramic radiography and CBCT were enrolled. The relationship between the posterior teeth and the maxillary sinus and panoramic radiography signs (projection of the root apices, interruption of the maxillary sinus floor, lamina dura, darkening in the root apices, and superiorly curving sinus floor enveloping the associated tooth root) associated with protrusion of root apices into the sinus were evaluated.

RESULTS

There were differences between the imaging modalities about the positioning of the root apices regarding the sinus (p < 0.05). Only the projecting of the root apices and the interruption of the sinus floor on panoramic radiography were predictors for the root protrusion (p < 0.05). No significant association was observed for the other panoramic radiography signs (p > 0.05).

CONCLUSIONS

The root projection into the sinus and the interruption of the sinus floor are indicative signs of root protrusion into the sinus on CBCT.

Effect of delayed scanning on imaging and on the diagnostic accuracy of vertical root fractures in two photostimulable phosphor plates digital systems

AIM

To evaluate the influence of delayed scanning on images obtained with two PSPs digital systems and on the diagnostic accuracy of vertical root fracture (VRF) by means of objective and subjective analyses.

METHODOLOGY

Forty single-rooted human teeth were divided into two groups, one without VRFs and another with VRFs induced by a universal testing machine. Two digital systems (VistaScan(®) and Express(®) ) were used to radiograph all teeth, and the resulting plates were scanned at four time-points: T0-immediately, T1-30 min, T2-2 h and T3-4 h after exposure. An aluminium (Al) wedge was used to evaluate the change in mean grey values as each scan was delayed. Three observers screened all images for VRFs, and one-fourth of the sample was revaluated after thirty days. Areas under the receiver operating characteristic (ROC) curve, sensitivity, specificity and accuracy values were compared by anova.

RESULTS

Intra- and interobserver agreement ranged from moderate to substantial and fair to moderate, respectively. There was no significant difference amongst scan delays with regard to sensitivity, specificity and accuracy; however, there were significant differences in the area under the ROC curve, with the 4-h delayed scan being associated with lower values compared to the others (P = 0.019). As for objective analysis, there was a significant difference amongst all different scanning time-points for the two systems (P = 0.001), except between the 30-min and 2-h delayed scans in the VistaScan(®) system.

CONCLUSION

Whilst delayed scanning caused changes to the density of images acquired with the systems studied, it did not seem to interfere with VRF diagnosis except when scanning was delayed for 4 h, which should therefore be avoided.

Influence of CBCT enhancement filters on diagnosis of vertical root fractures: a simulation study in endodontically treated teeth with and without intracanal posts

OBJECTIVES

To evaluate the influence of CBCT enhancement filters on the diagnosis of vertical root fractures (VRFs) in teeth with and without metal posts.

METHODS

The crowns of 40 uniradicular human teeth were removed and all roots were prepared. 20 teeth were randomly selected, and VRFs were induced using a universal testing machine. The i-CAT (Imaging Sciences International, Hatfield, PA) CBCT was used to scan teeth with and without intracanal metal posts using the following parameters: 0.2 voxel size, 8 × 8-cm scan size and acquisition time of 26.9 s. Images were evaluated by three observers with and without the use of the following filters: S9, smooth, smooth 3 × 3, sharpen, sharpen-mild and sharpen 3 × 3.

RESULTS

Intra- and interobserver agreement ranged from poor to moderate. Images with and without CBCT filters did not show significant differences regarding the area under the receiver operating characteristic curve, as well as sensitivity (p > 0.05). As for accuracy, the sharpen-mild filter was superior to the sharpen (p = 0.03), but these filters did not differ from all others. For specificity, S9, smooth and original images were superior to sharpen (p < 0.01). Results for teeth without posts differed from those for teeth with metal posts in all cases (p < 0.05).

CONCLUSIONS

The use of enhancement filters in CBCT images has no influence on the diagnosis of VRFs in teeth with metal posts, and their use is not justified.

Influence of the artefact reduction algorithm of Picasso Trio CBCT system on the diagnosis of vertical root fractures in teeth with metal posts

OBJECTIVES

To assess the influence of the artefact reduction algorithm (AR) available on the Picasso Trio 3D(®) imaging system (Vatech, Hwaseong, Republic of Korea) on image quality [greyscale values, contrast-to-noise ratio (CNR) and artefact formation] and diagnosis of vertical root fractures (VRFs) in the teeth with intracanal metal posts.

METHODS

30 uniradicular teeth had their crowns removed and their roots endodontically treated to receive intracanal metal posts. In 20 teeth, both complete (n = 10) and incomplete (n = 10) VRFs were created. Each tooth was scanned twice, with and without AR activation. The mean and variation of greyscale values, as well as CNR, were calculated for all images. Subsequently, an evaluator compared the amount of artefact (cupping, white streaks and dark bands) in all images. Five evaluators rated for VRF presence using a five-point scale.

RESULTS

Mean greyscale values and CNR were significantly decreased in images acquired with the AR. The usage of the algorithm promoted an overall reduction of image artefacts. Regarding the diagnosis of complete and incomplete VRFs, the use of the AR had an overall negative impact on specificity and accuracy.

CONCLUSIONS

While indeed reducing artefact formation, the use of the AR, instead of improving the impact on the diagnosis of VRFs in teeth with intracanal metal posts, had a negative impact on the diagnosis.

The 'Sharpen' filter improves the radiographic detection of vertical root fractures

AIM

To compare the diagnostic accuracy of digital enhancement filters in the diagnosis of vertical root fractures.

METHODOLOGY

The sample consisted of 40 single-rooted teeth randomly divided into two groups: experimental and control. Vertical root fractures were induced in the experimental group using a universal testing machine. All teeth were individually radiographed with three different horizontal angles using the Digora Optime(®) digital system. Three observers separately examined the original and filtered images (3D Emboss, Negative, Sharpen and Shadow). The area under Receiver Operating Characteristic curve values (Az) for each protocol were compared by one-way anova with post hoc Bonferroni test. The significance level was set at 5%.

RESULTS

The highest Az value was obtained using the Sharpen filter, with significant differences from the original and other filtered images (P < 0.05). The 3D Emboss filter had the lowest Az value, which was significantly different from the other filtered images (P < 0.05).

CONCLUSION

When using the Digora Optime(®) system, the 'Sharpen' filter is recommended to improve the radiographic detection of vertical root fractures.

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.

Prevalence and characteristics of pneumatization of the temporal bone evaluated by cone beam computed tomography

The aim of this study was to determine the prevalence and characteristics of pneumatization of the glenoid fossa and articular eminence by means of cone beam computed tomography (CBCT) images. CBCT images of 658 patients (1316 joints) were evaluated to determine pneumatization in the articular eminence (PAT) and roof of the glenoid fossa (PGF). Age and gender were recorded for all patients and, for the cases of pneumatization, laterality and type (unilocular or multilocular) were noted. Its prevalence was correlated with gender, age and laterality by statistical analyses. 21.3% of individuals presented with PAT and 38.3% presented with PGF. Considering the temporomandibular joint, PAT was in 15.5% and PGF in 30.2%. Of PAT cases, 54.3% were unilateral and 45.7% bilateral; 3.4% were unilocular and 96.6% were multilocular. In the PGF cases, 42.5% were unilateral and 57.5% bilateral; 0.02% was unilocular and 99.8% were multilocular. There was no statistical difference regarding gender and age; but there was statistical difference regarding laterality, with higher frequency on the left side. In conclusion, there was a significant prevalence of PAT and PGF in the studied population; their prevalence seems higher than has been previously supposed.

Correlation of panoramic radiography and cone beam CT findings in the assessment of the relationship between impacted mandibular third molars and the mandibular canal

OBJECTIVES

The aim of this study was to assess the reliability of four panoramic radiographic findings, both individually and in association, in predicting the absence of corticalization between the mandibular canal and the third molar on cone beam CT (CBCT) images.

METHODS

The sample consisted of 72 individuals (142 mandibular third molars) who underwent pre-operative radiographic evaluation before extraction of impacted mandibular third molars. On panoramic radiographs, the most common signs of corticalization (darkening of roots, diversion of mandibular canal, narrowing of mandibular canal and interruption of white line) and the presence or absence of corticalization between the mandibular third molar and the mandibular canal on CBCT images were evaluated.

RESULTS

Darkening of roots and interruption of white line associated with the absence of corticalization between the mandibular third molar and the mandibular canal on CBCT images were statistically significant, both as isolated findings (p = 0.0001 and p = 0.0006, respectively) and in association (p = 0.002). No statistically significant association was observed for the other panoramic radiographic findings, either individually or in association (p > 0.05).

CONCLUSION

Darkening of roots and interruption of white line observed on panoramic radiographs, both as isolated findings and in association, were effective in determining the risk relationship between the tooth roots and the mandibular canal, requiring three-dimensional evaluation of the case.

Bilateral dentigerous cysts: review of the literature and report of an unusual case

Dentigerous cysts are common cysts of the jaws. They are associated with the crowns of permanent teeth, most frequently associated with impacted mandibular third molars. Bilateral dentigerous cysts are rare and generally occur in association with a developmental syndrome or systemic disease, such as mucopolysaccharidosis and cleidocranial dysplasia. Bilateral dentigerous cysts in the absence of a syndrome are rare and to date only 17 cases have been described. The following is a report of a case of unusual bilateral non-syndromic dentigerous cysts associated with mandibular second molar and maxillary third molar and a review of the literature. Bilateral dentigerous cysts in these locations have not been previously reported.