Measurement accuracy with a new dental panoramic radiographic technique based on tomosynthesis

Radiographic evaluation of mandibular third molars: an ex vivo comparative study between multilayer and conventional panoramic radiography

OBJECTIVES

To compare the multilayer panoramic radiography (MPAN) and conventional panoramic radiography (CPAN) in the evaluation of mandibular third molars using cone-beam computed tomography (CBCT) as a reference.

METHODS

CPAN, MPAN, and CBCT scans from 33 dry human mandibles were acquired using the OP300 Maxio unit, totalizing 56 mandibular third molars to be evaluated. Three examiners evaluated each third molar according to their position, depth of impaction in the mandibular ramus, proximity between the dental root apexes and the mandibular canal, and the presence of radiographic signs of proximity to the mandibular canal. In addition, when there was a distance between the root apexes and the mandibular canal, it was measured. As a reference, these same parameters were assessed in the CBCT scans by a fourth examiner. For the statistical analysis, the weighted Kappa, Bland Altman, and Wilcoxon tests were performed (α = 0.05).

RESULTS

The agreement between the assessments performed in the panoramic modalities with the CBCT ranged from 66.1% to 100.0% for the categorical variables. Overall, the agreement values of CPAN and MPAN with CBCT were similar. The distances between the dental root apex and the mandibular canal for both CPAN and MPAN were significantly underestimated compared to CBCT (p < 0.05). The intra- and interexaminer agreements of the examiners ranged from poor to almost perfect; in general, the agreements were higher in the evaluation performed in the MPAN than in the CPAN.

CONCLUSIONS

The MPAN performs similarly to CPAN for evaluating mandibular third molars and their proximity relationship to the mandibular canal.

CLINICAL RELEVANCE

Preoperative evaluation of lower mandibular third molars is usually performed using CPAN. Recently, a new tool, MPAN, was developed, which has not yet been tested for the evaluation of mandibular third molars and showed similar performance to CPAN in the present study. Future studies using MPAN are encouraged to evaluate other diagnostic tasks.

Implementation of a personal identification system using alveolar bone images

OBJECTIVE

In recent years, personal identification has been performed using antemortem panoramic X-ray images and postmortem-CT images. Using these, we have developed a personal identification method that focuses on the alveolar bone. This study examined the effectiveness of this method and aimed to implement a reproducible system.

MATERIALS AND METHODS

For personal identification, a total of 633 CT images and panoramic X-ray images belonging to three groups with different conditions were used.　These images were 160 sets in the same person group and 96,820 in the other groups. The similarity of alveolar bone images was calculated using the landmark method of Procrustes analysis. The processes were system implemented and the methodology was validated.

RESULTS

The ability to identify between the same person group and other person groups showed 0.9769 as the area under the curve (AUC: ROC curve). At the cutoff value of 4.978, there was no false rejection rate, but false acceptance rate was slightly higher.

CONCLUSION

This method was useful as a screening method for personal identification. In addition, system implementation was efficient and reduced human error. In the future, we aim to realize a more efficient personal identification method using distortion-corrected images and including auto-detective landmarks using deep learning.

Mapping of a multilayer panoramic radiography device

OBJECTIVE

To map the shape, location, and thickness of the focal trough of a panoramic radiography device with a multilayer imaging program.

METHODS

An acrylic plate (148 × 148 × 3 mm) containing 1156 holes distributed in a matrix of 34 × 34 rows was placed in the OP300 Maxio at the levels of the maxilla and mandible. 20 metal spheres (3.5 mm in diameter) were placed on the holes of the plate under 15 different arrangements and panoramic images were acquired for each arrangement at 66 kV, 8 mA, and an exposure time of 16 s. The resulting panoramic radiographs from the five image layers were exported, the horizontal and vertical dimensions of the metal spheres were measured in all images using the Image J software, and the magnification and distortion rates of the spheres were calculated. All metal spheres presenting a magnification rate lower than 30% in both vertical and horizontal dimensions and a distortion rate lower than 10% were considered to map the focal troughs of each of the five image layers.

RESULTS

All panoramic image layers had a curved shape ranging from 39° to 51° for both dental arches and varied in position and thickness. The anterior region of maxilla was anteriorly displaced when compared to the anterior region of the mandible for all layers. Image layers are thicker at the level of the mandible than those at the level of the maxilla; also, inner layers were thinner and outer layers were thicker.

CONCLUSION

All image layers in the studied panoramic radiography device had a curved shape and varied in position and thickness. The anterior region of maxilla was anteriorly displaced when compared to that of the mandible for all layers.

Dynamic focal plane estimation for dental panoramic radiography

PURPOSE

The digital panoramic radiography is widely used in dental clinics and provides the anatomical information of the intraoral structure along the predefined arc-shaped path. Since the intraoral structure varies depending on the patient, however, it is nearly impossible to design a common and static focal path or plane fitted to the dentition of all patients. In response, we introduce an imaging algorithm for digital panoramic radiography that can provide a focused panoramic radiographic image for all patients, by automatically estimating the best focal plane for each patient.

METHODS

The aim of this study is to improve the image quality of dental panoramic radiography based on a three-dimensional (3D) dynamic focal plane. The plane is newly introduced to represent the arbitrary 3D intraoral structure of each patient. The proposed algorithm consists of three steps: preprocessing, focal plane estimation, and image reconstruction. We first perform preprocessing to improve the accuracy of focal plane estimation. The 3D dynamic focal plane is then estimated by adjusting the position of the image plane so that object boundaries in the neighboring projection data are aligned or focused on the plane. Finally, a panoramic radiographic image is reconstructed using the estimated dynamic focal plane.

RESULTS

The proposed algorithm is evaluated using a numerical phantom dataset and four clinical human datasets. In order to examine the image quality improvement owing to the proposed algorithm, we generate panoramic radiographic images based on a conventional static focal plane and estimated 3D dynamic focal planes, respectively. Experimental results show that the image quality is dramatically improved for all datasets using the 3D dynamic focal planes that are estimated from the proposed algorithm.

CONCLUSIONS

We propose an imaging algorithm for digital panoramic radiography that provides improved image quality by estimating dynamic focal planes fitted to each individual patient's intraoral structure.

Radiographic evaluation of remodeling of mandible in adult South Indian population: Implications in forensic science

INTRODUCTION

Panoramic X-ray is an imagiological examination produced by a technique that exhibits images of the facial structure present in the upper and lower dental arches, as well as the support structures in the diagnosis of problems that require a broad view of the oral-maxillofacial complex, such as the assessment of traumatisms, extensive lesions, dental development, tooth retention, and growth anomalies. Many morphological and anatomical changes are exhibited by the mandible with the advancement of age and changes in gender, as well as dentoalveolar condition of the patient, and it can be assessed with the help of such radiograph, thus playing an important role in personal identification in forensic dentistry.

AIMS

This study aimed to evaluate the changes in gonial angle (GA), antegonial angle (AGA), and antegonial depth (AGD) in adult mandible with regard to age, gender, and dental status using panoramic radiographs.

SETTINGS AND DESIGN

This cross-sectional retrospective study was done using hospital records.

SUBJECTS AND METHODS

A total of 100 panoramic radiographs were evaluated. The images were grouped into three age groups (40-70) of 10 years each. GA, AGA, and AGD were digitally measured from the radiographs.

STATISTICAL ANALYSIS USED

Descriptive statistics of the variables were expressed in percentage, frequencies, mean, and standard deviations. Statistical differences between the variables were explored using independent sample t-test and one-way ANOVA. The significant level was set as 0.05.

RESULTS

There were no significant changes in GA, AGA, and AGD with age and dental status of the patients. Males had significantly smaller GA and AGA than females. Understandably, AGD was significantly greater in males than females.

CONCLUSIONS

Remodeling changes of the mandible with respect to the age groups and dental status studied were minimal. However, gender-related differences in ante AGA, depth, and GA were significant, which can be used as a tool in forensic identification.

Evaluation of Mandibular Anatomical Formation for Gender Determination in Turkish Population

Background/Aim: Gender determination is one of the most challenging tasks in medico-legal research and forensic dentistry. Several skeletal components are investigated for this purpose and the mandible is one of them. The mandible has several specific anatomical features. The purpose of this study was to analyze the effects of measurements related to the mental foramen, gonial angle and antegonial angle on gender determination using digital panoramic radiographs.

Material and Methods: A retrospective study was planned with 150 digital panoramic radiographs (75 males and 75 females, aged between 20 to 49 years). The radiographs were analyzed by dividing them into two equal gender groups (male and female). Several parameters were compared to determine the gender. The distances from the superior and inferior border of the mental foramen to the basis of the mandible on the right side were measured. Gonial and antegonial angles were evaluated bilaterally. The difference between the males and females were analyzed with independent samples t-test (p<0.05).

Results: There was statistically significant difference between the males and females in terms of all the evaluated parameters (p<0.05). The distances related to mental foramen is higher in the males however gonial and antegonial angles are larger in the females.

Conclusions: The mental foramen position, gonial and antegonial angles can be used to predict the gender in Turkish population.

Accuracy and head positioning effects on measurements of anterior tooth length using 3-dimensional and conventional dental panoramic radiography

INTRODUCTION

The purposes of this study were to examine the accuracy and the head positioning effects on measurements of anterior tooth length using 3-dimensional (3D) and conventional dental panoramic radiography and to investigate whether 3D panoramic radiography is suitable for the evaluation of anterior tooth length.

METHODS

A simulated human head was radiographed at 4, 8, and 12 mm displaced positions, and at 5°, 10°, and 15° tilted positions from the standard head position using 3D and conventional panoramic radiography, and also using cone-beam computed tomography. Anterior tooth lengths were measured on the panoramic and cone-beam computed tomography images. The values for the standard head position in the panoramic radiographs were defined as the standard values. Measurement error was defined as the standard value minus the cone-beam computed tomography value on each panoramic radiograph. The head position ratio of the measurement value to the standard value at each head position was calculated.

RESULTS

Measurement errors for the 3D panoramic radiographs were significantly smaller than those for the conventional panoramic radiographs. In the 3D panoramic radiographs, the head position ratios at the 4, 8, and 12 mm displaced positions and at the 5° tilted position were within ±5% of the standard value.

CONCLUSIONS

Three-dimensional panoramic radiography is suitable for the quantitative evaluation of anterior tooth length with high accuracy.

An update on carbon nanotube-enabled X-ray sources for biomedical imaging

A new imaging technology has emerged that uses carbon nanotubes (CNT) as the electron emitter (cathode) for the X-ray tube. Since the performance of the CNT cathode is controlled by simple voltage manipulation, CNT-enabled X-ray sources are ideal for the repetitive imaging steps needed to capture three-dimensional information. As such, they have allowed the development of a gated micro-computed tomography (CT) scanner for small animal research as well as stationary tomosynthesis, an experimental technology for large field-of-view human imaging. The small animal CT can acquire images at specific points in the respiratory and cardiac cycles. Longitudinal imaging therefore becomes possible and has been applied to many research questions, ranging from tumor response to the noninvasive assessment of cardiac output. Digital tomosynthesis (DT) is a low-dose and low-cost human imaging tool that captures some depth information. Known as three-dimensional mammography, DT is now used clinically for breast imaging. However, the resolution of currently-approved DT is limited by the need to swing the X-ray source through space to collect a series of projection views. An array of fixed and distributed CNT-enabled sources provides the solution and has been used to construct stationary DT devices for breast, lung, and dental imaging. To date, over 100 patients have been imaged on Institutional Review Board-approved study protocols. Early experience is promising, showing an excellent conspicuity of soft-tissue features, while also highlighting technical and post-acquisition processing limitations that are guiding continued research and development. Additionally, CNT-enabled sources are being tested in miniature X-ray tubes that are capable of generating adequate photon energies and tube currents for clinical imaging. Although there are many potential applications for these small field-of-view devices, initial experience has been with an X-ray source that can be inserted into the mouth for dental imaging. Conceived less than 20 years ago, CNT-enabled X-ray sources are now being manufactured on a commercial scale and are powering both research tools and experimental human imaging devices. WIREs Nanomed Nanobiotechnol 2018, 10:e1475. doi: 10.1002/wnan.1475 This article is categorized under: Diagnostic Tools > Diagnostic Nanodevices Diagnostic Tools > In Vivo Nanodiagnostics and Imaging.

Age and gender correlation of gonial angle, ramus height and bigonial width in dentate subjects in a dental school in Far North Queensland

Background

This study aimed to determine if mandibular parameters (gonial angle, bigonial width and ramus height) measured from panoramic radiographs, can be used to determine a correlation with an individual’s age and gender in dentate subjects in Far North Queensland.

Material and Methods

The study utilised 2699 randomly selected panoramic radiographs of patients between the ages of 19-69 years, from which 220 fulfilled the inclusion criteria. Each panoramic radiograph was analysed and the above three parameters recorded and measured. These values were collated into appropriate age and gender groups and subjected to statistical analysis.

Results

The mean age of the participants was 44.1±14.41, with males being shown to have a statistically significant larger ramus height and bigonial width than females (P<0.0001 for both). Females, on the other hand, were shown to have a significantly larger gonial angle than males (P<0.0002). General trends revealed gonial angle to increase with age, whilst bigonial width and ramus height were shown to decrease with age.

Conclusions

The assessment of mandibular morphology through radiographic measurements may be useful in estimating an individual’s age and gender when comparing to a known population standard.

Key words:Bigonial width, gonial angle, panoramic radiograph, ramus height.

Reliability of semiquantitative assessment of osteophytes and subchondral cysts on tomosynthesis images by radiologists with different levels of expertise

PURPOSE

We aimed to assess reliability of the evaluation of osteophytes and subchondral cysts on tomosynthesis images when read by radiologists with different levels of expertise.

MATERIALS AND METHODS

Forty subjects aged >40 years had both knees evaluated using tomosynthesis. Images were read by an "experienced" reader (musculoskeletal radiologist with prior experience) and an "inexperienced" reader (radiology resident with no prior experience). Readers graded osteophytes from 0 to 3 and noted the presence/absence of subchondral cysts in four locations of the tibiofemoral joint. Twenty knees were randomly selected and re-read. Inter- and intrareader reliabilities were calculated using overall exact percent agreement and weighted κ statistics. Diagnostic performance of the two readers was compared against magnetic resonance imaging readings by an expert reader (professor of musculoskeletal radiology).

RESULTS

The experienced reader showed substantial intrareader reliability for graded reading of osteophytes (90%, κ=0.93), osteophyte detection (95%, κ=0.86) and cyst detection (95%, κ=0.83). The inexperienced reader showed perfect intrareader reliability for cyst detection (100%, κ=1.00) but intrareader reliability for graded reading (75%, κ=0.79) and detection (80%, κ=0.61) of osteophytes was lower than the experienced reader. Inter-reader reliability was 61% (κ=0.72) for graded osteophyte reading, 91% (κ=0.82) for osteophyte detection, and 88% (κ=0.66) for cyst detection. Diagnostic performance of the experienced reader was higher than the inexperienced reader regarding osteophyte detection (sensitivity range 0.74-0.95 vs. 0.54-0.75 for all locations) but diagnostic performance was similar for subchondral cysts.

CONCLUSION

Tomosynthesis offers excellent intrareader reliability regardless of the reader experience, but experience is important for detection of osteophytes.

The cadmium telluride photon counting sensor in panoramic radiology: gray value separation and its potential application for bone density evaluation

OBJECTIVE

To investigate whether bone mineral density can be evaluated more accurately using a panoramic device with a new cadmium telluride photon-counting sensor and software than 2 panoramic devices with a conventional semiconductor sensor.

STUDY DESIGN

A fiduciary test object with several known levels of hydroxy apatite mineral concentration was placed in a phantom on the mandibular occlusal plane. Panoramic images were acquired by changing the position of the test object within the dental arch. The gray value, the spectrum deformation index (SDI), and the relative attenuation index (RAI) of the test object were evaluated. The SDI and RAI represent unique energy information as acquired by the QR-Master panoramic machine and the corresponding special QR-MC analysis software. In order to compare the values expressed in the different units (gray, SDI, and RAI values), the percentage discrepancy was calculated.

RESULTS

The cadmium telluride photon-counting fitted machine more consistently separated each of the hydroxy apatite concentrations in all of the different positioning configurations and locations. The SDI function of the QR Master machine produced more stable values than the RAI value and the gray values of the 2 conventional panoramic machines.

CONCLUSIONS

The methodologies as developed for this study can be used to test more sophisticated analyses for the determination of bone density.

From 2D to 3D: Construction of a 3D Parametric Model for Detection of Dental Roots Shape and Position from a Panoramic Radiograph-A Preliminary Report

Objectives. To build a 3D parametric model to detect shape and volume of dental roots, from a panoramic radiograph (PAN) of the patient. Materials and Methods. A PAN and a cone beam computed tomography (CBCT) of a patient were acquired. For each tooth, various parameters were considered (coronal and root lengths and widths): these were measured from the CBCT and from the PAN. Measures were compared to evaluate the accuracy level of PAN measurements. By using a CAD software, parametric models of an incisor and of a molar were constructed employing B-spline curves and free-form surfaces. PAN measures of teeth 2.1 and 3.6 were assigned to the parametric models; the same two teeth were segmented from CBCT. The two models were superimposed to assess the accuracy of the parametric model. Results. PAN measures resulted to be accurate and comparable with all other measurements. From model superimposition the maximum error resulted was 1.1 mm on the incisor crown and 2 mm on the molar furcation. Conclusion. This study shows that it is possible to build a 3D parametric model starting from 2D information with a clinically valid accuracy level. This can ultimately lead to a crown-root movement simulation.