Effective dose of dental CBCT-a meta analysis of published data and additional data for nine CBCT units

Projected lifetime cancer risk from cone-beam computed tomography for orthodontic treatment

Objective

To estimate the projected cancer risk attributable to diagnostic cone-beam computed tomography (CBCT) performed under different exposure settings for orthodontic purposes in children and adults.

Methods

We collected a list of CBCT machines and their specifications from 38 orthodontists. Organ doses were estimated using median and maximum exposure settings of 105 kVp/156.8 mAs and 130 kVp/200 mAs, respectively. The projected cancer risk attributable to CBCT procedures performed 1-3 times within 2 years was calculated for children (aged 5 and 10 years) and adult (aged 20, 30, and 40 years) male and female patients.

Results

For maximum exposure settings, the mean lifetime fractional ratio (LFR) was 14.28% for children and 0.91% for adults; this indicated that the risk to children was 16 times the risk to adults. For median exposure settings, the mean LFR was 5.25% and 0.58% for children and adults, respectively. The risk of cancer decreased with increasing age. For both median and maximum exposure settings, females showed a higher risk of cancer than did males in all age groups. Cancer risk increased with an increase in the frequency of CBCT procedures within a given period.

Conclusions

The projected dental CBCT-associated cancer risk spans over a wide range depending on the machine parameters and image acquisition settings. Children and female patients are at a higher risk of developing cancer associated with diagnostic CBCT. Therefore, the use of diagnostic CBCT should be justified, and protective measures should be taken to minimize the harmful biological effects of radiation.

The suitability of panoramic radiographs for clinical decision making regarding root angulation compared to cone-beam computed tomography

BACKGROUND

The study compared clinical decisions regarding root angulation correction and root proximity based on the interpretation of Panoramic (PAN) versus Cone-Beam Computed Tomography (CBCT) images.

METHODS

A total of 864 teeth from 36 existing, radiographic patient records at a university dental clinic with concurrent PAN and CBCT images were assessed using PANs, then using CBCTs in a blinded manner by two orthodontists. Teeth were rated regarding the need for root repositioning, the direction of repositioning and existence of root proximity. Frequencies, rating time and intra- and inter-examiner Cohen's Kappa were calculated.

RESULTS

There was 73.7-84.5% agreement between PAN-based and CBCT-based orthodontists' decisions regarding the need to reposition roots. Root proximity was more frequently reported on PANs than CBCTs by one examiner (p = 0.001 and p = 0.168). Both PANs and CBCTs had moderate to substantial intra-examiner, within-radiograph-type reliability with Kappa values of 0.686-0.79 for PANs, and 0.661 for CBCTs (p < 0.001). Inter-examiner and inter-radiograph-type Kappa values ranged from 0.414 to 0.51 (p < 0.001). Using CBCT decisions as a reference, 78.9% of PAN decisions were coincident, 9.3% would have been repositioned on CBCT but not on PAN, 11.3% would not have been repositioned on CBCT but were on PAN, and 0.3% would have been repositioned in the opposite direction on CBCT versus PAN. Additionally, CBCT images required more time per tooth to assess than PANs (p < 0.001).

CONCLUSIONS

PAN-based clinical decisions regarding root angulation had comparable statistical reliability and substantial agreement with CBCT-based clinical decisions.

Endodontic length measurements using 3D Endo, cone-beam computed tomography, and electronic apex locator

BACKGROUND

The objective of this study is to investigate the accuracy of the 3D Endo software, cone-beam computed tomography (CBCT) software, and the electronic apex locator (EAL) in endodontic length determination.

METHODS

302 root canals in 111 human extracted molars were chosen. Access cavity was performed, and root canal lengths were measured with a digital caliper for actual length (AL) and EAL for electronic length. Teeth were then scanned using CBCT device at voxel size of 0.10 mm. It measured root canal lengths using the CBCT (Romexis Viewer), 3D Endo for proposed length (3D-PL) and correct length (3D-CL). Mean differences between the four methods with the AL were calculated and compared. Fisher's exact test, paired t-test, Bland-Altman plot were used to test the differences among the experimental modalities in working length determination at the significance of 0.05.

RESULTS

The accuracy in the range of ± 0.5 mm of the EAL ProPex II was highest among the experimental modalities, however this method disagreed with the actual length.

CONCLUSIONS

The correct working length after adjustment from the semi-automatically length by the 3D Endo software and Romexis Viewer measurements agreed with the AL.

Endodontic length measurements using cone beam computed tomography with dedicated or conventional software at different voxel sizes

The aim of this study is to investigate the accuracies and the agreements of the 3D Endo software, conventional CBCT software Romexis Viewer at three voxel sizes, and the EAL ProPex Pixi in endodontic length measurements. Three hundred and twenty-nine root canals in 120 intact human extracted molars were accessed. The actual lengths (AL) and electronic lengths (EL) were measured using the ruler and electronic apex locator (EAL), respectively. Teeth were scanned using the CBCT at different voxel sizes (0.075, 0.10, and 0.15 mm). Root canal lengths were measured using 3D Endo with proposed length (3D-PL) by software, corrected length (3D-CL), Romexis Viewer. The Fisher's exact test, paired t-test and Bland-Altman plots were calculated to detect the agreements of the four methods with AL measurements. The ProPex Pixi measurements obtained the highest accuracy in the range of ± 0.5 mm. There was agreement between the 3D-PL and the 3D-CL with AL measurements at voxel size of 0.15 mm and at voxel size of 0.10 mm, respectively. The CBCT Romexis Viewer measurements agreed with AL at three voxel sizes. The conventional CBCT measurements using Romexis Viewer and dedicated software did not reach to the 100% accuracy in the range of ± 0.5 mm.

Radiographic Evaluation of Prosthodontic Patients

This article focuses on radiographic imaging with regard to planning, treating, and maintaining partially and completely edentulous prosthodontic patients with dental implants. Cone-beam computed tomography (CBCT) is the preferred imaging method for pretreatment dental implant treatment planning. Radiographic guides containing radiopaque materials and/or fiducial markers transfer both the proposed prosthesis design and desired implant location for appropriate radiographic evaluation. The three-dimensional CBCT analysis provides information on the adjacent relevant anatomy, bone volume of the edentulous sites, and restorative space assessment.

Effective dose estimation in cone-beam computed tomography for dental use by Monte-Carlo simulation optimizing calculation numbers using a step-and-shoot method

OBJECTIVE

The objective of this study was to perform effective dose estimation in cone-beam CT for dental use (CBCT) using a Monte-Carlo simulation employing a step-and-shoot method as well as to determine the optimal number of steps.

METHODS

We simulated 3DX Accuitomo FPD8 as a CBCT model and estimated the effective doses of a large and a small field of view (FOV) examination against the virtual Rando phantom using a particle and heavy ion transport code system. We confirmed the results compared to those from a thermo-luminescence dosemeter (TLD) system in a real phantom and investigated how the reduced angle calculations could be accepted.

RESULTS

The effective doses of both FOVs estimated with each one degree were almost the same as those estimated from the TLD measurements. Considering the effective doses and the itemized organ doses, simulation with 5° and 10° is acceptable for the large and small FOV, respectively. We tried to compare an effective dose with a large FOV as well as with multiple small FOVs covering the corresponding area and found that the effective dose from six small FOVs was approximately 1.2 times higher than that of the large FOVs.

CONCLUSION

We successfully performed a Monte-Carlo simulation using a step-and-shoot method and estimated the effective dose in CBCT. Our findings indicate that simulation with 5° or 10° is acceptable based on the FOV size, while a small multiple FOV scan is recommended from a radiation protection viewpoint.

Estimation of the radiation dose for dental spectral cone-beam CT

OBJECTIVES

The purpose of this study was to estimate the radiation dose for a dental spectral cone-beam CT (SCBCT) unit at different scanning parameters.

METHODS

Radiation dose measurements were performed for a commercially available dental SCBCT. Scans were obtained at different exposure times and fields of view (FOV), both for non-spectral (25×18 cm, 14×18 cm, 14×12 cm, 9×9 cm, 6×6 cm) and spectral modes (14×18 cm, 14×12 cm, 9×9 cm, 6×6 cm) with the tube voltage alternating between 80 and 110 kV for spectral mode, and fixed at 110 kV for non-spectral mode. An ion chamber was used for air kerma and dose area product (DAP) measurements. The effective dose was estimated based on the mAs using previously published logarithmic curves for CBCT units with a similar X-ray spectrum.

RESULTS

The adult effective dose, in non-spectral mode, was 44-269 µSv for small FOVs, 131-336 µSv for the medium FOV, and 163-476 µSv for the large FOV. In spectral mode, the estimated adult effective doses were 96-206 µSv for small, 299 µSv for medium and 372 µSv for large FOV protocols. Paediatric effective doses were estimated to be 75% higher than corresponding adult doses.

CONCLUSION

SCBCT showed comparable doses with other CBCT devices, but DAP values were generally above currently published DRLs. Spectral imaging might allow for artefact reduction at comparable dose levels, which should be assessed in further image quality studies at both a technical and diagnostic levels.

Age-dependent decrease in dental pulp cavity volume as a feature for age assessment: a comparative in vitro study using 9.4-T UTE-MRI and CBCT 3D imaging

Evaluation of secondary dentin formation is generally suitable for age assessment. We investigated the potential of modern magnetic resonance imaging (MRI) technology to visualize the dental pulp in direct comparison with cone beam computed tomography (CBCT). To this end, we examined 32 extracted human teeth (teeth 11–48 [FDI]) using 9.4-T ultrashort echo time (UTE)-MRI and CBCT (methods). 3D reconstruction was performed via both manual and semi-automatic segmentation (settings) for both methods in two runs by one examiner. Nine teeth were also examined by a second examiner. We evaluated the agreement between examiners, scan methods, and settings. CBCT was able to determine the pulp volume for all teeth. This was not possible for two teeth on MRI due to MRI artifacts. The mean pulp volume estimated by CBCT was consistently higher (~ 43%) with greater variability. With lower variability in its measurements, evaluation of pulp volume using the MRI method exhibited greater sensitivity to differences between settings (p = 0.016) and between examiners (p = 0.009). The interactions of single-rooted teeth and multi-rooted teeth and method or setting were not found to be significant. For examiner agreement, the mean pulp volumes were similar with overlapping measurements (ICC > 0.995). Suitable for use in age assessment is 9.4-T UTE-MRI with good reliability and lower variation than CBCT. For MRI, manual segmentation is necessary due to a more detailed representation of the interior of the pulp cavity. Since determination of pulp volume is expected to be systematically larger using CBCT, method-specific reference values are indispensable for practical age assessment procedures. The results should be verified under in vivo conditions in the future.

Low-dose Multidetector Computed Tomographic and Cone-beam Computed Tomographic Protocols for Volumetric Measurement of Simulated Periapical Lesions

INTRODUCTION

The purpose of this study was to evaluate the accuracy of low-dose multidetector computed tomographic (LD-MDCT) imaging for the volumetric measurement of simulated periapical lesions.

METHODS

Eighteen monoradicular teeth were introduced in bone blocks, and periapical lesions were simulated at the periapical region of each tooth. All teeth were imaged using 4 acquisition protocols: large (dentoalveolar) field of view (FOV) cone-beam computed tomographic (CBCT) imaging (120 kV, 5 mA, and 0.2-mm voxel), small (dental) FOV CBCT imaging (90 kV, 10 mA, and 0.2-mm voxel), standard multidetector computed tomographic imaging (120 kV, 50 mA, and 0.62-mm voxel), and LD-MDCT imaging (120 kV, 10 mA, and 0.62-mm voxel). Tomographic images were evaluated by a single trained and calibrated examiner (intraclass correlation coefficient = 0.991) using ITK-SNAP segmentation software (University of Pennsylvania, Philadelphia, PA). The gold standard was obtained by the impressions of the lesions with regular fluid addition silicone and individual weighing using a precision analytical scale. Data were evaluated by the repeated measures analysis of variance test; the significance level was defined as P < .05.

RESULTS

No statistical differences (P > .05) were found among the groups regardless of the device, milliamperage, FOV, or voxel size.

CONCLUSIONS

LD-MDCT shows performance comparable with other standard reference methods for measuring the volume of periapical lesions and can be a useful and safe protocol in clinical situations in which CBCT imaging is not available, such as in cases of patients admitted to hospitals.

Cone-Beam Computed Tomography: A User-Friendly, Practical Roadmap to the Planning and Execution of Every Rhinoplasty-A 5-Year Review

BACKGROUND

Cone-beam computed tomography has recently rapidly developed worldwide as a versatile and convenient alternative to traditional computed tomography for imaging of the maxillofacial region. However, most surgeons performing rhinoplasty are surprisingly unfamiliar with it, in both the plastic surgery and ear, nose, and throat communities.

METHODS

The broad clinical experience of a single center over the past 5 years is reviewed. The many applications of cone-beam computed tomography to primary and secondary rhinoplasty are analyzed regarding septum, turbinates, nasal bones, skin thickness, and other issues. The importance of a paradigm shift from a two-dimensional to a three-dimensional approach in image reconstruction is demonstrated, together with the value of surface contour enhancement.

RESULTS

Cone-beam computed tomography has a multitude of practical applications highly relevant to rhinoplasty. The surface image will strengthen aesthetic analysis, and the detailed preview of bony and functional anatomy will facilitate surgical planning. Cone-beam computed tomography serves as a roadmap to plan and execute rhinoplasties more predictably and efficiently. The availability of spatial views and accurate detail, together with the possibility of easy, accurate measuring, offers a plenitude of potential applications.

CONCLUSIONS

Cone-beam computed tomography is a user-friendly, quick technique with abundant advantages in planning any rhinoplasty. It causes the patient no inconvenience and has very few, if any, drawbacks, with these being limited to radiation exposure and limited cost.

Suitability of Magnetic Resonance Imaging for Guided Endodontics: Proof of Principle

INTRODUCTION

This proof-of-principle study aimed to demonstrate that magnetic resonance imaging (MRI) is sufficiently accurate for the detection of root canals using guided endodontics.

METHODS

One hundred extracted human teeth (anterior and premolar) were mounted onto 5 mandibular and 5 maxillary models, fitted with splints designed to accommodate a thin layer of aqueous gel for indirect imaging, and scanned by MRI. After MRI and intraoral scans were aligned using planning software, access cavities were planned virtually, and templates were manufactured with computer-aided design/computer-aided manufacturing, the access cavities were prepared. Cone-beam computed tomographic scans were performed and matched with the virtual preoperative planning data to determine the accuracy of access cavity preparation in terms of deviation between planned and prepared cavities in the mesiodistal and buccolingual dimensions and angle. Descriptive statistical analysis was performed, and the mean values were compared using the t test.

RESULTS

Ninety-one of 100 root canals were successfully scouted after MRI-guided access cavity preparation. The mean angle deviation was 1.82°. The mean deviation ranged from 0.21-0.31 mm at the base of the bur and from 0.28-0.44 mm at the tip of the bur. Preparation in the buccolingual dimension was significantly more precise in mandibular compared with maxillary teeth, and accuracy in the mesiodistal dimension was more precise in anterior teeth compared with premolars.

CONCLUSIONS

This in vitro study demonstrated the suitability of MRI for guided endodontic access cavity preparation.

A controlled study on the diagnostic accuracy of panoramic and peri-apical radiography for detecting furcation involvement

BACKGROUND

The aims of this study were (1) to determine the accuracy, sensitivity, and specificity of panoramic and peri-apical radiographs in diagnosing furcation involvement, as well as (2) to evaluate the possible impact of clinical experience on these diagnostic parameters.

METHODS

An existing radiographic dataset of periodontitis patients requiring implant surgery was retrospectively examined for furcation involvement. Criteria for inclusion were the presence of a CBCT, panoramic and peri-apical radiograph of the site of interest within a one-year time frame. All furcation sites were classified using the CBCT, which was considered as the gold standard, according to Hamp's index (1975). Ten experienced examiners and 10 trainees were asked to assess furcation involvement for the same defects using only the corresponding panoramic and peri-apical radiographs. Absolute agreement, Cohen's weighted kappa, sensitivity, specificity and ROC-curves were analyzed.

RESULTS

The study sample included 60 furcation sites in 29 multi-rooted teeth from 17 patients. On average, 20/60 furcations were correctly classified according to the panoramic radiographs, corresponding to a weighted kappa score of 0.209, indicating slight agreement. Similarly, an average of 19/60 furcations were correctly classified according to the peri-apical radiographs, corresponding to a weighted kappa score of 0.211, also indicating slight agreement. No significant difference between panoramic and peri-apical radiography was found (P = 0.903). When recategorizing FI Grades into 'no to limited FI' (FI Grade 0 and I) and 'advanced FI' (FI Grade II and III), the panoramic and peri-apical radiography showed low sensitivity (0.558 and 0.441, respectively), yet high specificity (0.791 and 0.790, respectively) for identifying advanced FI. The ROC-curves for the panoramic and peri-apical radiographs were 0.79 and 0.69 respectively. No significant difference was found between experienced periodontists and trainees (P = 0.257 versus P = 0.880).

CONCLUSION

Panoramic and peri-apical radiography are relevant tools in the diagnosis of FI and provide high specificity. Ideally, they are best used in combination with furcation probing, which shows high sensitivity. Furthermore, clinical experience does not seem to improve the accuracy of a radiological diagnosis of furcation sites.

TRIAL REGISTRATION

Patient radiographic datasets were retrospectively analyzed.

Advanced platelet-rich fibrin plus and osseous bone graft for socket preservation and ridge augmentation - A randomized control clinical trial

Objective

To compare the clinical and radiographic effectiveness of A PRF Plus as an adjuctive material to osseous bone graft in socket preservation and ridge augmentation.

Methods

Twenty patients with need to preserve extraction socket in non-molar sites planning for further prosthetic rehabilitation were divided into two groups. Test Group (Group A) was treated with A PRF Plus membrane and Sybograf plus ™ (70% HA and 30 %β TCP) bone graft. The Control Group (Group B) was treated with Sybograf plus ™ (70% HA and 30% βTCP) bone graft. Both groups had same socket preservation surgical technique.

Results

Both Group A and Group B showed significant improvement in clinical and radiographic parameters. Mean socket length, Vertical Resorption reduction in Group A was 1.48 whereas in Group B was 1.67 which is statistically significant. (p ​≤ ​0.05). Changes in Horizontal width reduction at 1,3, and 5 ​mm depth of the socket for both groups were not statistically significant. The Gain in socket fill for Group A and B 6 months postoperatively was 1185.30HU ± 473.21 and 966.60 HU ± 273.27 respectively. But intergroup comparison was not statistically significant. (p ​= ​0.17). There were no significant statistical differences in postoperative pain in Group A and Group B as subjects experienced moderate amount of pain. The assessment of post-operative swelling showed that only 30% subjects in Group A reported with swelling. Whereas 80% subjects in Group B complained of post-operative swelling.

Conclusion

The results of the present study proved utilisation of A PRF Plus as a promising adjunct to conventional regenerative therapy for socket preservation.

Planning and Osteotomy Designs in the Correction of Single-Suture Craniosynostosis

BACKGROUND

Craniosynostosis is among the abnormalities that are more commonly encountered by craniofacial surgeons. Although the overall concepts for cranial vault remodeling are relatively simple, osteotomy designs and methods for calvarial rearrangement are highly varied. In this work, we present a summary of the known designs for correction of single-suture craniosynostosis.

METHODS

A review of the literature was performed of the more frequently used osteotomy designs for single-suture craniosynostosis, as well as their reported results and outcomes. Also reviewed are some of the current available approaches for the diagnosis and surgical planning for single-suture craniosynostosis.

RESULTS

There remains a diversity of techniques available for the reconstruction of each fused cranial suture. Certain osteotomy designs are reported in the literature and are used by craniofacial surgeons more frequently. Each has its own benefits and disadvantages, and there is a growing body of outcome data available to guide surgical decision-making. Regarding diagnosis and surgical planning, computed tomography with 3-dimensional reconstruction remains the diagnostic standard of care, and efforts are ongoing to develop and implement new diagnostic modalities like Black Bone MRI to reduce radiation exposure.

CONCLUSIONS

There has been ongoing evolution of the surgical techniques available to reconstruct single-suture craniosynostosis, leading to ever-improving patient outcomes.

Modern 3D cephalometry in pediatric orthodontics-downsizing the FOV and development of a new 3D cephalometric analysis within a minimized large FOV for dose reduction

OBJECTIVES

Dose reduction achieved by downsizing the field of view (FOV) in CBCT scans has brought no benefit for pediatric orthodontics, until now. Standard 2D or 3D full-size cephalometric analyses require large FOVs and high effective doses. The aim of this study was to compare a new 3D reduced-FOV analysis using the Frankfurt horizontal (FH) plane as reference plane with a conventional full-size analysis using the Sella-Nasion (S-N) plane as reference plane.

MATERIALS AND METHODS

Thirty-eight CBCT data sets were evaluated using full- and reduced-FOV analysis. The measurements of a total of 20 skeletal and dental standard 3D full-size variables were compared with the measurements of 22 corresponding 3D reduced-FOV variables. Statistical analysis was performed to prove mathematic relation between standard and alternative variables. Regression analyses were carried out.

RESULTS

Coefficients of determination (R²) between 0.15 and 0.95 (p < 0.001-0.055) were described. All variables showed obvious relations of different strength except for SNA and its alternative Po_R-Or_R-A (°) (R² = 0.15, p = 0.055), but a second variable Ba_A (mm) showed stronger relation (R² = 0.28, p = 0.003).

CONCLUSIONS

All standard variables related to the reference plane S-N could be described with alternative variables related to the FH. Further research should define more reliable landmarks for coordinate systems and reference points.

CLINICAL RELEVANCE

Minimized large FOVs meet the demand of 3D cephalometric analyses and enable the application of CBCT scans in pediatric orthodontic patients in many specific indications. Dose reduction is accompanied by increasing access to all the advantages of 3D imaging over 2D imaging.

A review of dental cone-beam CT dose conversion coefficients

OBJECTIVE

The purpose of this study was to review the literature to examine the usage and magnitude of effective dose conversion factors (DC_E) for dental cone beam CT (CBCT) scanners.

METHODS

A PubMed literature search for publications relating to radiation dosimetry in dental radiography was performed. Papers were included if they reported DC_E, or reported ICRP 103 effective dose and dose-area product. 71 papers relating to dental CBCT dosimetry were found, of which eight reported effective dose conversion factors or provided enough information to calculate dose conversion factors. Scanner model, effective dose, dose-area product, tube voltage, field of view size and DC_E were extracted from the papers for analysis.

RESULTS

DC_E values ranged from 0.035 to 0.31 µSv/mGy-cm² with a mean of 0.129 µSv/mGy-cm² (SD = 0.056). When categorized into small (<100 cm²), medium (100-225 cm²) and large (>225 cm²) fields of view (FOV), linear fits to the effective dose and dose-area product yielded slopes of 0.129, 0.111 and 0.074 µSv/mGy-cm² for small, medium and large FOVs respectively.

CONCLUSION

The range of reported DC_E values and spread with respect to field of view category suggests that DC_E values that depend on FOV would provide more accurate effective dose estimates. Tube voltage was found to be a smaller factor in determining DC_E. Reasonable values for DC_E taking into account FOV size were obtained. There is considerable room for more work to be done to examine the behaviour of DC_E with changes to patient age and dental CBCT imaging parameters.

Endodontic Length Measurements Using Different Modalities: An In Vitro Study

INTRODUCTION

The aim of this study was to investigate and compare the accuracy of the 3D Endo software, conventional CBCT software Romexis Viewer, and the EAL E-Pex Pro in WL determination.

MATERIALS AND METHODS

Three hundred and two root canals in 110 intact human extracted molars were accessed. The actual lengths (ALs) were measured. Root canal lengths were measured using 3D Endo with proposed length (3D-PL) by software, correct length (3D-CL), Romexis Viewer, and the E-Pex Pro. The percentages of the measurements in the range of ±0.5 mm to the AL were compared using the Fisher's exact test. The paired t test and Bland-Altman plots were calculated to detect the agreement of the four methods with the AL measurements. The statistical significance was set at P<0.05.

RESULTS

The accuracies in the range of ±0.5 mm to the AL were 83.8%, 86.7%, 48.3%, and 99.7% for 3D-PL, 3D-CL, Romexis Viewer, and E-PexPro, respectively. There were agreements between 3D-PL and Romexis Viewer with the AL measurements.

CONCLUSION

The CBCT measurements using 3D Endo with the proposed length by the software and Romexis Viewer with the voxel size of 0.15 mm agreed with the AL measurements of the root canals.

Guidelines for oral and maxillofacial imaging: COVID-19 considerations

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus causing the current coronavirus disease 2019 (COVID-19) pandemic, is not only highly infectious but can induce serious outcomes in vulnerable individuals including dental patients and dental health care personnel (DHCPs). Responses to COVID-19 have been published by the Centers for Disease Control and Prevention and the American Dental Association, but a more specific response is required for the safe practice of oral and maxillofacial radiology. We aim to review the current knowledge of how the disease threatens patients and DHCPs and how to determine which patients are likely to be SARS-CoV-2 infected; consider how the use of personal protective equipment and infection control measures based on current best practices and science can reduce the risk of disease transmission during radiologic procedures; and examine how intraoral radiography, with its potentially greater risk of spreading the disease, might be replaced by extraoral radiographic techniques for certain diagnostic tasks. This is complemented by a flowchart that can be displayed in all dental offices.

Intraoral radiographs: A comparison of dose and risk reduction with collimation and thyroid shielding

BACKGROUND

The National Commission on Radiation Protection and Measurements has reinforced its recommendation for the use of rectangular collimation for intraoral radiography in its Report No. 177 published in 2019. This study compared effective dose (E) using circular and rectangular collimator (RC) modalities.

METHODS

The authors exposed 18 projections for adult and 12 projections for child full-mouth series using an original equipment 6 centimeter diameter circular collimator (circular), original equipment rectangular positioning indicator device (Focus-RC), and 5 universal RC modalities (JadRad-RC, Rinn-RC, Durr-RC, DEXshield-RC, and TruAlign-RC) for adult and child phantoms. The authors acquired dosimetry using optically stimulated luminescence dosimeters. Exposures were made with a Focus (Instrumentarium) intraoral source using 70 peak kilovoltage and total milliamperes of 5.34 (adult) and 2.7 (child).

RESULTS

Adult E was lowest for Focus-RC (54 microsieverts), which also produced the greatest exposure area reduction (51%) compared with circular, followed by JadRad-RC (55 μSv), Durr-RC (58 μSv), Rinn-RC (62 μSv), DEXshield-RC (70 μSv), TruAlign-RC (85 μSv), and circular (86 μSv). Child E followed a similar trend: Focus-RC (44 μSv), JadRad-RC (44 μSv), Durr-RC (45 μSv), Rinn-RC (48 μSv), DEXshield-RC (53 μSv), TruAlign-RC (85 μSv), and circular (89 μSv). When used with thyroid shielding, circular collimation thyroid dose was reduced by as much as 59%.

CONCLUSIONS

Focus-RC techniques yielded the greatest dose reduction compared with alternative RC and circular. In addition to shape, collimator dimensions should be considered as significant factors affecting patient E. RC alone yielded a greater reduction in thyroid dose than did circular with thyroid shielding.

PRACTICAL IMPLICATIONS

This study's findings underscore the updated recommendations of the National Commission on Radiation Protection and Measurements Report No.177, which emphasized the benefits and important practical considerations of RC with intraoral imaging.

Imaging Anatomy of the Jaw and Dentition with Cone Beam Computed Tomography

Knowledge of dental, maxillary, and mandibular anatomy and the use of correct nomenclature is critical in the evaluation of a mandibulofacial and/or maxillofacial imaging data set. The use of the correct diagnostic imaging tool tailored to the patient's needs is of equal importance. This article highlights imaging anatomy and cross-sectional imaging modalities mainly focusing on cone beam computed tomography of the mandibulofacial and maxillofacial region.

Use of preoperative cone-beam computed tomography to aid in establishment of endodontic working length: A systematic review and meta-analysis

Purpose

This study was performed to assess the accuracy of preoperative cone-beam computed tomography (CBCT), when justified for other reasons, in locating the apical foramen and establishing the working length.

Materials and Methods

Six electronic databases were searched for studies on this subject. All studies, of any type, were included if they compared measurements of working length with preoperative CBCT to measurements using an electronic apex locator (EAL) or histological reference standard. Due to the high levels of heterogeneity, an inverse-variance random-effects model was chosen, and weighted mean differences were obtained with 95% confidence intervals and P values.

Results

Nine studies were included. Compared to a histological reference standard, CBCT indicated that the apical foramen was on average 0.40 mm coronal of its histological position, with a mean absolute difference of 0.48 mm. Comparisons were also performed to an EAL reference standard, but the conclusions could not be considered robust due to high levels of heterogeneity in the results.

Conclusion

A low level of evidence is produced suggesting that preoperative CBCT shows the apical foramen to be on average 0.40 mm coronal to its histological position, with a mean absolute difference of 0.48 mm.

Voxel-based superimposition of Cone Beam CT scans for orthodontic and craniofacial follow-up: Overview and clinical implementation

INTRODUCTION

The increasing use of three-dimensional (3D) imaging in orthodontics has led to the development of 3D superimposition techniques. These techniques use stable anatomic structures as references in order to compare Cone Beam CT (CBCT) scans of the same subject at different time-points. Three methods have been described in the literature: landmark-based, surface-based and voxel-based 3D superimpositions.

OBJECTIVE

This article focuses on the voxel-based approach, which is the most described and the only one that can be fully automatized. The aim of this paper is to offer clinicians a practical tutorial on craniofacial voxel-based 3D superimposition.

MATERIAL AND METHODS

We provide an updated overview of the available implementation methods, describing their methodology, validations, main steps, advantages and drawbacks. The historical open-source method is the most widespread for research purposes, but takes around three hours to achieve for an experienced operator. Several commercially-available software perform superimpositions in a few minutes.

RESULTS

We used two of the available methods to conduct the superimposition process with three representative clinical cases in order to illustrate the different types of results that can be obtained.

CONCLUSIONS

Commercially-available software provide user-friendly and fully automatized superimposition methods, allowing clinicians to perform it easily and helping to reduce human error in image analysis. Still, quantitative evaluation of the results remains the main challenge of this technique.

Quantitative Performance Characterization of Radiation Dose for the Carestream CS9600 Cone-Beam Computed Tomography Machine

INTRODUCTION

Cone-beam computed tomography (CBCT) machines produce relatively low levels of harmful ionizing radiation, as compared with the computed tomography devices used in medical practices. The Carestream CS9600 CBCT imaging device has been recently introduced into the marketplace, and the manufacturer reports the use of an increased x-ray tube voltage (120 kVp) for the device, along with a reduced patient dose that is achieved using added filtration. Independent dosimetry studies are performed to ensure appropriate radiation exposure dose levels are within recommended safety guidelines.The purpose of this study is to independently evaluate and measure the radiation exposure dose performance parameters of the CS9600 CBCT, including its multiple field of view, exposure settings, and filtration options.

METHODS

A thimble ionization chamber and PMMA phantom were used to characterize dose index using the established SEDENTEXTCT evaluation method.

RESULTS

The phantom-obtained radiation dose index measures ranged from 0.128782-13.848 milligrays (mGy) for the various scanning options evaluated. The field of view, type of filter used, and phantom size all had a direct impact on the relationship between the experimentally obtained dose index measures and the dose area product values reported by the manufacturer.

CONCLUSIONS

A strong linear correlation was observed between the experimentally obtained dose index measures and the manufacturer-reported dose area product values. The 0.7 mm Cu filter that has been added to the CS9600 reduced the exposure dose index measures even with the x-ray tube kilovoltage peak (kVp) being increased to 120 kVp, as compared with the 0.15 mm Cu filter at 90 kVp.

Three-dimensional qualitative and quantitative analyses of the effect of periradicular lesions on the outcome of regenerative endodontic procedures: A prospective clinical study

OBJECTIVES

Qualitative and quantitative evaluation of the outcomes of regenerative endodontic procedure (REP) on human immature necrotic teeth with apical periodontitis using cone-beam computed tomography (CBCT) MATERIALS AND METHODS: Immature permanent teeth (n = 50) with necrotic pulp and periradicular pathosis were treated with a cell-homing concept-based REP. Following the procedure, a limited field-of-view CBCT scan was obtained. At each recall session (6, 12, 18 months), clinical tests were performed, and a digital periapical radiograph was taken. When significant radiographic changes were evident in the follow-up, a final CBCT scan was taken for qualitative and quantitative assessment. These initial and follow-up CBCT scans were assessed for quantification of changes in root length, pulp space diameter and periradicular lesion size. The data were statistically analysed using t test, one-way ANOVA, post hoc test and paired t test (P = 0.05).

RESULTS

Of the teeth, 94.6% were clinically successful based on the lack or regression of signs and symptoms after 48 months follow-up. REP resulted in a statistically significant increase in root length, decrease in pulp space diameter and periradicular radiolucency (P < 0.05). CBCT images illustrated various patterns of root maturation including an increased thickening of the canal walls and continued root maturation (37.1%), continued root development with the apical foramen remaining open (57.1%), severe calcification (obliteration) of the canal space (2.9%) and hard tissue barrier formation in the canal space between the coronal plug and the root apex (2.9%).

CONCLUSION

This study highlighted that the expected outcome of radiographic root development was less predictable when immature permanent teeth with periradicular pathosis were treated with REP.

CLINICAL RELEVANCE

The size and extent (expansion/destruction of the cortical plate) of periradicular lesions and abscesses influence the outcome of REP. These factors must be taken into consideration during treatment planning.

EXTRAORAL AND CBCT DENTAL EXPOSURES IN PORTUGAL

Data from dental extraoral and cone beam computed tomography (CBCT) exposures in Portugal (2019) were gathered, and patient doses for standard adult exams were evaluated. In panoramic X-rays, 442 units (34% of the existing licensed units) were tested, with a third quartile value (PKA) of 82 mGy.cm2. For cephalometric radiography (88 units), the third quartile value (Ki) was 0.3 mGy for the posteroanterior projection and 0.2 mGy for lateral projection. In CBCT (69 units), the doses for the placement of an upper first molar implant were evaluated with a third quartile value (PKA) of 820 mGy.cm2. Due to the wide range of values (74-3687 mGy.cm2), the CBCT data were divided by FOV dimensions: for small FOV (average FOV of 7 ×8 cm), a value of 580 mGy.cm2 was obtained and for medium FOV (average FOV of 13 × 12 cm) a value of 1167 mGy.cm2. The number of annual panoramic X-rays made in Portugal was 208 per 1000 inhabitants, which is higher than the value for other countries.

Management of Impacted Third Molars

Impacted third molars occur in a significant number of patients and often require treatment because of presence of symptoms and/or disease. Management of these teeth typically involves referral to oral and maxillofacial surgeons for diagnosis, treatment planning, and ultimate removal if indicated. Proper diagnosis and treatment planning helps optimize surgical results at each stage of the procedure, and ultimately patient outcomes. Adherence to proper surgical techniques helps minimize risks and complications associated with the procedure. Multiple alternative surgical techniques also exist for uncommon, but potentially complicated, situations that arise with some impacted third molars.

Establishment of national diagnostic reference levels in dental cone beam computed tomography in Switzerland

OBJECTIVES

The aim of this study was to establish diagnostic reference levels (DRLs) in the field of dental maxillofacial and ear-nose-throat (ENT) practices using cone beam CT (CBCT) in Switzerland.

METHODS

A questionnaire was sent to owners of CBCTs in Switzerland; to a total of 612 institutions. The answers were analyzed for each indication, provided that enough data were available. The DRLs were defined as the 75th percentile of air kerma product distribution (PKA).

RESULTS

227 answers were collected (38% of all centers). Third quartile of PKA values were obtained for five dental indications: 662 mGy cm² for wisdom tooth, 683 mGy cm² for single tooth implant treatment, 542 mGy cm² for tooth position anomalies, 569 mGy cm² for pathological dentoalveolar modifications, and 639 mGy cm² for endodontics. The standard field of view (FOV) size of 5 cm in diameter x 5 cm in height was proposed.

CONCLUSIONS

Large ranges of FOV and PKA were found for a given indication, demonstrating the importance of establishing DRLs as well as FOV recommendations in view of optimizing the present practice. For now, only DRLs for dental and maxillofacial could be defined; because of a lack of ENT data, no DRL values for ENT practices could be derived from this survey.

Low-dose cone-beam computed tomography in simulated condylar erosion detection: a diagnostic accuracy study

OBJECTIVES

The purpose of the present study was to assess the diagnostic accuracy of low-dose cone-beam computed tomography (CBCT) in the detection of simulated mandibular condyle erosions.

METHODS

102 simulated erosions were performed on the condyles of eight dry human mandibles. Each mandible was subjected to four CBCT scan protocols: high-definition (HD), normal definition (NORM), ultra-low-dose high-definition (ULD-HD), and ultra-low-dose normal definition (ULD-NORM). All scans were analyzed by two observers. The inter-observer and intra-observer agreement as well as the agreement with the gold standard were assessed. The sensitivity, specificity, positive-predictive value, negative-predictive value and accuracy of erosion detection were calculated.

RESULTS

A substantial to almost perfect agreement with the gold standard was found regarding the HD protocol and substantial agreement in NORM and ULD-HD protocols; however, moderate agreement was found regarding the ULD-NORM protocol. The sensitivity, specificity and accuracy values were highest for the HD protocol followed by the NORM and ULD-HD which showed comparable results; while, the ULD-NORM protocol showed the least values.

CONCLUSIONS

The studied ULD-HD CBCT protocol can be recommended for the detection of mandibular condylar erosions due to the reduced radiation dose; however, ULD-NORM is not advocated for similar clinical use.

Accuracy of mean grey density values obtained with small field of view cone beam computed tomography in differentiation between periapical cystic and solid lesions

AIM

To determine if small and medium field of view (FOV) cone beam computed tomography (CBCT) adjusted grey density values can be used to distinguish between periapical cystic and solid lesions.

METHODOLOGY

Fifty-seven patients with periapical lesions having retrievable small or medium FOV CBCT images and biopsy samples were included. Two oral and maxillofacial pathologists examined the biopsy samples to provide the gold standard diagnosis of cystic or solid lesion. From the CBCT images, two independent examiners recorded the minimum adjusted grey density value of each lesion twice. Intra-examiner and inter-examiner reliability of the measurements were analysed, and sensitivity, specificity and accuracy of the minimum grey values in distinguishing a solid from cystic lesion were calculated. A receiver operating curve for diagnostic ability of adjusted grey density values to differentiate between periapical cystic and solid lesions was obtained, and the area under the curve (AUC) was calculated.

RESULTS

The intra- and inter-examiner reliability of the grey density values of the lesions and dentine were excellent. The AUC was 0.44 (P-value = 0.45). The adjusted grey density value with the greatest accuracy for differentiating between cystic and solid lesions had an accuracy, sensitivity and specificity of 0.54, 1.00 and 0.075, respectively.

CONCLUSIONS

Small FOV CBCT adjusted grey density values obtained by the device used in the study could not distinguish between periapical cystic and solid lesions. Further developments in CBCT devices are needed to improve the accuracy of grey density measurements.

Effective doses of dental cone beam computed tomography: effect of 360-degree versus 180-degree rotation angles

OBJECTIVES

The aims of this study were to compare radiation absorbed dose (AD) and effective dose (ED) to tissues from cone beam computed tomography (CBCT) scans with 360-degree versus 180-degree rotations with use of different fields of view (FOV), to compare EDs calculated from measured ADs versus dose area product (DAP) values, and to compare doses to the lens of the eye (LOE) from different scan parameters.

STUDY DESIGN

ADs for each protocol were measured in tissues, including the LOE, by using an anthropometric phantom. EDs were calculated on the basis of dosimetry (EDm) and DAP values (EDd). Dose differences were determined with analysis of variance (ANOVA).

RESULTS

ADs and EDs were substantially lower for 180-degree rotation scans compared with 360-degree rotation scans (P < .01). Remainder tissues had the greatest effect on effective dose for most FOVs. Doses were generally lower with small FOVs compared with large FOVs. Most EDm values were lower than EDd values in large FOVs but higher in small FOVs. Differences in EDm and EDd were variable and unpredictable. LOE doses were smaller with the 180-degree scans and smaller FOVs.

CONCLUSIONS

Radiation doses were generally lower with 180-degree rotation scans and smaller FOVs. These parameters should be used for CBCT acquisitions, whenever possible, and should be made available in all units.

Outcomes of different radioprotective precautions in children undergoing dental radiography: a systematic review

PURPOSE

To evaluate the effectiveness of all radioprotective measures in underage patients who undergo a dental radiodiagnostic examination.

METHODS

A systematic review was performed including randomised controlled trials (RCTs), or cluster trials, cohort studies, cross-sectional studies, case-control studies and comparative in vitro research. These studies examined the healthy underage human population (below 18 years) undergoing a dental radiodiagnostic examination. All radioprotective measures were included except for justification as an intervention. The primary outcomes were in vivo mortality and morbidity. Some surrogate or indirect outcomes such as in vitro effective dose and organ absorbed doses were also accepted. Secondary outcomes with regards to image quality and therapeutic value were also analysed.

RESULTS

Eighteen papers were eligible for implementation. Fifteen studies underwent narrative synthesis. Regression analysis was performed on three studies.

CONCLUSION

The following radioprotective measures can reduce the exposure dose. For lateral cephalometry: collimation, filtration, the fastest receptor type and circumstantial thyroid shielding. For oblique lateral radiographs: the shortest exposure time, a smaller horizontal angulation, a longer focus to skin distance. For intraoral radiography: rectangular collimation, the fastest image receptor speed and thyroid shielding when the thyroid gland is in line of or very close to the primary beam. For panoramic radiographs: collimation, the fastest receptor type and the use of automatic exposure control (AEC) or manual adjustment of intensity. For cone-beam computed tomography: collimation, the largest voxels size in relation to the treatment need, change in image settings such as ultra-low dose settings, shorter exposure time, a lower amount of projections, lower beam intensity, reduction of the potential, use of a thyroid shield except in two situations and the use of AEC. All of the changes in exposure parameters should be performed while maintaining a sufficient therapeutic value on an individual and indication-based level.

Cone beam computed tomography in dentomaxillofacial radiology: a two-decade overview

OBJECTIVES

The aim of this study was to evaluate and summarise features of currently and formerly available cone beam CT (CBCT) devices from 1996 to 2019. Additionally, a recommendation for standardised reporting of CBCT characteristics was provided.

METHODS AND MATERIALS

Information about the features of all available CBCT devices was obtained from the manufacturers' available data. Moreover, site visits to newly developed CBCT machines' manufacturers were performed in order to obtain relevant information.

RESULTS

A total of 279 CBCT models from 47 manufacturers located in 12 countries (Brazil, China, Denmark, Finland, France, Germany, Italy, Japan, Republic of Korea, Slovakia, Thailand, and USA) could be listed. Overall, wide variations in CBCT features and technical specifications were identified.

CONCLUSIONS

CBCT in dentomaxillofacial radiology is a generic term applicable to a broad range of CBCT machines and features. Experimental outcomes and literature statements regarding radiation doses, imaging performance and diagnostic applicability of dental CBCT cannot be simply transferred from one CBCT model to another considering a wide variation in technical characteristics and clinical diagnostic performance. The information tabulated in the present study will be later provided on the International Association of DentoMaxilloFacial Radiology website (www.iadmfr.one).

Image retake rates of cone beam computed tomography in a dental institution

OBJECTIVES

To investigate the frequency and reasons for retaking cone beam computed tomography (CBCT) scans in an oral and maxillofacial radiology imaging clinic in a dental institution.

MATERIALS AND METHODS

A retrospective cohort chart audit of the patient image database was performed for 1737 patients attending the Diagnostic Imaging clinic at the Prince Philip Dental Hospital from February 2016 to May 2019, and the rate of, and reasons for, CBCT image re-exposure was tallied. Patient demographics (age and gender) and CBCT acquisition parameters (CBCT unit, field-of-view (FOV), scanned region of interest, and exposure time) were recorded and correlated to retake analysis.

RESULTS

The retake rate was 4.6% (80/1737). The most common reasons for re-exposure were incomplete FOV coverage (57.5%) and motion artifacts (27.5%). Patients under 12 years of age had a significantly higher risk for motion artifacts. CBCT for the temporomandibular joint (TMJ) had a significantly higher risk for incomplete FOV coverage.

CONCLUSIONS

Children (less than 12 years of age) demonstrate a higher frequency of retakes, principally due to motion artifacts. TMJ CBCT examinations have a higher frequency of retakes due to an incomplete FOV coverage.

CLINICAL RELEVANCE

Information regarding the frequency and reasons for CBCT retakes is beneficial to identify procedures, practices, or patients susceptible to additional radiation exposure and implement appropriate and specific quality control protocols.

Effect of CBCT dose reduction on the mandibular canal visibility: ex vivo comparative study

OBJECTIVES

To compare the difference in mandibular canal (MC) visibility using three different cone beam computed tomography (CBCT) acquisition protocols: high resolution (HR), standard resolution (ST) and Quick scan+ (QS+).

METHODS

Twenty-five human dry mandibles were scanned by one CBCT machine; i-CAT FLX (Imaging Sciences International, Hatfield, PA, USA), using three different acquisition protocols: high-resolution (HR), standard (ST) and Quick scan+ (QS+). DICOM data were transferred to a third party software Ondemand 3D (Cybermed Co., Seoul, Korea). The fusion module was used to superimpose images derived from different acquisition protocols to standardize the areas to compare the MC visibility. Comparison was performed at nine selected cross sections extending from an area distal to the third molar posteriorly to the first premolar anteriorly. Two expert radiologists evaluated the degree of MC visibility using five-scale scoring system.

RESULTS

There was a statistically significant difference between the three acquisition protocols (HR, ST, QS+) at all investigated areas regardless of dentition status (p value < 0.001-0.034) except at the MR1M area where there was no statistically significant difference (p value = 0.094). HR protocol showed the highest prevalence of fully and partially corticated MC at almost all investigated areas while QS+ protocol showed the highest prevalence of invisible MC and clear and unclear non-corticated MC at almost all investigated areas.

CONCLUSIONS

QS+ protocol of i-CAT FLX CBCT machine is a recommended low-dose CBCT acquisition protocol for MC visibility at dentulous posterior mandibular regions while ST protocol is recommended at edentulous areas.

Cone-beam computed tomography and its applications in dental and maxillofacial radiology

Cone-beam computed tomography (CBCT) was first used in dental and maxillofacial radiology (DMFR) at the end of the 1990s. Since then, it has been successfully established as the standard three-dimensional radiographic imaging technique in DMFR, with a wide variety of applications in this field. This manuscript briefly reviews the background information on the technology and summarises available data on effective dose and dose optimisation. In addition, typical clinical applications and indications of the technique in DMFR are presented.

3D Assessment of Endodontic Lesions with a Low-Dose CBCT Protocol

Background: Cone beam computed tomography (CBCT) is often used in different fields of dental science, especially in complex anatomical districts like the endodontic one. The aim of this study is to propose a low-dose CBCT protocol useful in cases of endodontic lesions. Methods: The device used was a MyRay Hyperion X9-11x5; the low dose setting of the machine was 90 Kv, 27 mAs, CTDI/Vol 2.89 mGy. The absorbed organ doses have been evaluated with an anthropomorphic phantom loaded with thermoluminescent dosimeters positioned at the level of sensitive organs like brain, bone marrow, salivary glands, thyroid, esophagus, oral mucosa, extrathoracic airways, and lymph nodes. Equivalent and effective doses have been calculated; the last one has been calculated using the recommendations approved by the Main Commission of ICRP (International Commission Radiological Protection) in March 2007. For the assessment of image quality, five senior clinicians, independent and experienced clinicians, were asked to state if CBCT scans were accurate enough to assess endodontic lesions. Results: The use of a low-dose CBCT acquisition produced the lowest organ dose (5.01 microSv) at the level of the esophagus. Image quality has been considered accurate enough for endodontic diagnostic needs. Conclusions: CBCT low-dose protocol can be used over the standard one in endodontic special cases because it provides a significantly lower radiation dose to the patients while ensuring good image quality. However, further studies are necessary to evaluate the opportunity of low-dose CBCT exams in endodontic clinical practice.

Improved scan method for dental imaging using multidetector computed tomography: a phantom study

OBJECTIVES

This study aimed to propose an improved scan method to shorten irradiation time and reduce radiation exposure.

METHODS

The maxilla of a human head CT phantom and a Catphan phantom were used for qualitative and quantitative assessment, respectively. The phantoms were scanned by a 160-row multidetector CT scanner using volumetric and helical scanning. In volumetric scanning, the tube current varied from 120 to 60 to 30 to 20 mA with a tube voltage of 120 kV. Images were reconstructed with a bone kernel using iterative reconstruction (IR) and filtered back projection. As a reference protocol, helical scanning was performed using our clinical setting with 120 kV. Two dental radiologists independently graded the quality of dental images using a 4-point scale (4, superior to reference; 1, unacceptable). For the quantitative assessment, we assessed the system performance from each scan.

RESULTS

There was no significant difference between the image quality of volumetric scanning using the 60 mA protocol reconstructed with IR and that of the reference (3.08 and 3.00, p = 0.3388). The system performance values at 1.0 cycles/mm of volumetric scanning and 60 mA protocol reconstructed with IR and reference were 0.0038 and 0.0041, respectively. The effective dose of volumetric scanning using the 60 mA protocol was 51.8 µSv, which is a 64.2% reduction to that of the reference.

CONCLUSIONS

We proposed an improved scan method resulting in a 64.2% reduction of radiation dose with one-fourth of irradiation time by combining volumetric scanning and IR technique in multidetector CT.

Dose assessment in dental cone-beam computed tomography: Comparison of optically stimulated luminescence dosimetry with Monte Carlo method

The variety of cone-beam computed tomography (CBCT) machines and their applications has rapidly increased in recent years, making the dose evaluation of individual devices an important issue. Patient doses from CBCT were assessed with two different methods: optically stimulated luminescence dosimeter (OSLD) measurements and Monte Carlo (MC) simulations, in four different examination modes. Based on an analysis of the measurement process and the obtained values, a recommendation is made regarding which method is more practical and efficient for acquiring the effective dose of CBCT. Twenty-two OSLDs were calibrated and equipped in human phantoms of head and neck organs. They were exposed to radiation from two CBCT units—CS9300 (Carestream Dental LLC, Atlanta, Georgia) and RAYSCAN α+ (Ray Co. Ltd, Hwaseong-si, Korea)—using two different examination modes. The dose recorded using the OSLDs was used to calculate the organ dose and the effective dose for each unit in each examination mode. These values were also calculated using MC software, PCXMC (STUK, Helsinki, Finland). The organ doses and effective doses obtained using both methods were compared for each examination mode of the individual units. The OSLD-measured effective dose value was higher than that obtained using the MC method for each examination mode, except the dual jaw mode of CS9300. The percent difference of the effective dose between the two methods ranged from 4.0% to 14.3%. The dose difference between the methods decreased as the field of view became smaller. The organ dose values varied according to the method, although the overall trend was similar for both methods. The organs showing high doses were mostly consistent for both methods. In this study, the effective dose obtained by OSLD measurements and MC simulations were compared, and both methods were described in detail. As a relatively efficient and easy-to-perform method, we cautiously suggest using MC simulations for dose evaluations in the future.

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.

CBCT does not reduce neurosensory disturbances after third molar removal compared to panoramic radiography: a systematic review and meta-analysis

OBJECTIVES

The current dentistry scenario is showing an increase in the availability of cone-beam computed tomography (CBCT) in dental offices. Oral surgeons are using three-dimensional information as an additional tool to assess preoperative data for lower third molar (LTM) removal in moderate and high-risk cases of inferior alveolar nerve (IAN) injury diagnosed through the panoramic radiography (PR). The aim of this study is to identify whether CBCT examination reduces neurosensoric disturbances (ND) following the removal of the LTM when compared to PR.

MATERIALS AND METHODS

PubMed, Embase, Web of Science, Science Direct, and Scopus electronic databases were searched for studies published up to February 2019. The gray literature was also searched including papers that eventually met the eligibility criteria. Meta-analysis was performed using the comprehensive meta-analysis software, p < 0.05 considered significant.

RESULTS

Among the search, 6 studies met all eligibility criteria. There was no statistically significant difference between the two groups (PR and CBCT) in all six studies regarding reducing ND (95%. Confidence interval, 0,788-1734; heterogeneity: Q = 10,361; I² = 22.788%).

CONCLUSIONS

CBCT was not superior to PR in avoiding ND. However, further studies are necessary with standardized parameters for a better comparability between variables in the studies.

CLINICAL RELEVANCE

To better understand the CBCT clinical applicability in LTM removal to avoid unnecessary extra radiation when compared to PR to the patient and to improve patient's prognosis.

Comparison between Micro-Computed Tomography and Cone-Beam Computed Tomography in the Assessment of Bone Quality and a Long-Term Volumetric Study of the Augmented Sinus Grafted with an Albumin Impregnated Allograft

The purpose of our study was to compare micromorphometric data obtained by cone-beam computed-tomography (CBCT) and microcomputed-tomography (micro-CT) of the augmented sinus and to evaluate the long-term stability of the bone gain achieved using BoneAlbumin. Sinus lifts, and after 6-months, healing bone-biopsy and implant placement were carried out. Specimens were analyzed by micro-CT. A total of 16 samples were collected from nine patients (mean age 54.7 ± 6.5 years). Pre-, postoperative, and 3-year control CBCT-data were registered to determine from where the biopsy samples were harvested. Micromorphometric variables were calculated from the micro-CT- and CBCT-data, and their correlation was determined by Spearman's test. The volume of augmented bone was calculated at the time of implant placement and after 3 years. A positive correlation was found between bone-volume fraction, trabecular-separation, open-, and total-porosity, while a negative correlation was found between trabecular-thickness obtained from CBCT- and micro-CT-data (p < 0.05). Mean volumetric reduction of 39.28% (11.88-60.02%) was observed. Correlation of CBCT- and micro-CT-data suggested that micromorphometric analysis of CBCT reconstructions of the augmented sinuses provided reliable information on the microarchitecture of augmented bone. CBCT as a modality might be adequate in the analysis of bone quality in the augmented sinus. At the 3-year, control sinus grafts showed volumetric stability.

Prevalence of nasal septum deviation using cone-beam computed tomography: A cross-sectional study

Background and Aim:

Nasal septum deviation (NSD) increases the chance of nasal obstruction, sinusitis, and upper airway and middle ear infections and can affect vocal cord activity, beauty, and breathing. The present study investigated the prevalence of NSD and its relation to gender, age, and history of trauma using cone-beam computed tomography (CBCT).

Subjects and Methods:

This cross-sectional study was performed on the data from CBCT examinations of 386 patients referred to two oral and maxillofacial radiology centers in Tehran, Iran, from January 2016 to January 2017. The presence of NSD and its type according to the Mladina's classification were evaluated. The effect of age, gender, and history of trauma on the prevalence of NSD was considered using a logistic regression.

Results:

86.6% (confidence interval = 0.81, 0.91) of the patients showed NSD. The prevalence was 19.4% type 1, 6.2% type 2, 20.7% type 3, 5.4% type 4, 4.4% type 5, 0.3% type 6, and 30.3% with type 7. The logistic regression indicated that the chance of deviation of nasal septum increased with age and every 10-year increase in age increased the odds of septal deviation by 0.32 (P < 0.001 and odds ratio = 1.032). Gender (P = 0.094) and history of trauma (P = 0.79) had no effects on the chance of deviation of nasal septum.

Conclusion:

This study showed that the frequency of NSD was 86.6%, with type 7 being the most common type, followed by type 3 and 1. NSD showed no association with trauma and gender, and the increase in age increases the chance of NSD.

Accuracy of the measurements from multiplanar and sagittal reconstructions of CBCT

OBJECTIVES

The purpose of this study was to assess the accuracy of linear measurements performed in multiplanar reconstructions (MPR) and sagittal reconstructions (SR) of the left hemiface obtained from cone-beam computed tomography (CBCT) with 3D^® Dolphin Imaging software by comparing them with the same measurements made on lateral cephalograms and on dry skulls.

SETTING AND SAMPLE POPULATION

Lateral cephalograms and CBCT (with voxels of 0.25, 0.3 and 0.4 mm) were taken of 10 dry skulls.

MATERIALS AND METHODS

Linear distances were measured using the software's electronic rulers. Measurements performed on dry skulls using a digital caliper were considered the gold standard. The measurements were performed twice by two evaluators.

RESULTS

No significant difference was found in the measurements performed with the different imaging modalities and on the dry skulls. The highest mean error was observed in the lateral cephalograms, followed by MPR and SR.

CONCLUSIONS

Cephalometric measurements performed on multiplanar and sagittal reconstructions from CBCT, with different spatial resolutions, are accurate when compared with the measurements obtained in lateral cephalograms.