Automated landmark identification on cone-beam computed tomography: Accuracy and reliability

ObjectivesTo evaluate the accuracy and reliability of a fully automated landmark identification (ALI) system as a tool for automatic landmark location compared with human judges.Materials and MethodsA total of 100 cone-beam computed tomography (CBCT) images were collected. After the calibration procedure, two human judges identified 53 landmarks in the x, y, and z coordinate planes on CBCTs using Checkpoint Software (Stratovan Corporation, Davis, Calif). The ground truth was created by averaging landmark coordinates identified by two human judges for each landmark. To evaluate the accuracy of ALI, the mean absolute error (mm) at the x, y, and z coordinates and mean error distance (mm) between the human landmark identification and the ALI were determined, and a successful detection rate was calculated.ResultsOverall, the ALI system was as successful at landmarking as the human judges. The ALI''s mean absolute error for all coordinates was 1.57 mm on average. Across all three coordinate planes, 94% of the landmarks had a mean absolute error of less than 3 mm. The mean error distance for all 53 landmarks was 3.19 ± 2.6 mm. When applied to 53 landmarks on 100 CBCTs, the ALI system showed a 75% success rate in detecting landmarks within a 4-mm error distance range.ConclusionsOverall, ALI showed clinically acceptable mean error distances except for a few landmarks. The ALI was more precise than humans when identifying landmarks on the same image at different times. This study demonstrates the promise of ALI in aiding orthodontists with landmark identifications on CBCTs.     

Reproducibility of maxillofacial landmark identification on three-dimensional cone-beam computed tomography images of patients with mandibular prognathism: Comparative study of a tentative method and traditional cephalometric analysis

Objective:To clarify the reproducibility of a tentative method for identifying maxillofacial landmarks on three-dimensional (3D) images obtained with cone-beam computed tomography (CBCT) for dental use in patients with mandibular prognathism. Also, the influence of level of experience of dentists applying the method was investigated by dividing them into two groups according to experience.Materials and Methods:Dentists with less (group A) or more (group B) than 3 years of experience of cephalometry and 3D image manipulation analyzed CBCT data from 10 patients using two different landmark identification methods: method 1 used conventional cephalometric definitions and method 2 used detailed landmark identification definitions developed for each cross-sectional plane. The plotting of nine landmarks was performed twice, and 10 coordinate values were obtained for each landmark. To assess reproducibility, the 95% confidence ellipse method was used.Results:Comparative analysis showed that method 2 was highly reproducible. Group B subjects attained smaller ellipsoid volumes than group A subjects, regardless of the landmark identification method used. With method 1, except for condyle and coronoid process, all landmarks showed a higher level of reproducibility in group A subjects than in group B subjects. With method 2, however, five landmarks showed no differences between the methods.Conclusion:The method proposed here may be highly reproducible regardless of the evaluators'' experience.     

A Novel Method to Estimate the Volume of Bone Defects Using Cone-Beam Computed Tomography: An In Vitro Study

Introduction

The routine use of high-resolution images derived from 3-dimensional cone-beam computed tomography (CBCT) datasets enables the linear measurement of lesions in the maxillary and mandibular bones on 3 planes of space. Measurements on different planes would make it possible to obtain real volumetric assessments. In this study, we tested, in vitro, the accuracy and reliability of new dedicated software developed for volumetric lesion assessment in clinical endodontics.

Methods

Twenty-seven bone defects were created around the apices of 8 teeth in 1 young bovine mandible to simulate periapical lesions of different sizes and shapes. The volume of each defect was determined by taking an impression of the defect using a silicone material. The samples were scanned using an Accuitomo 170 CBCT (J. Morita Mfg Co, Kyoto, Japan), and the data were uploaded into a newly developed dedicated software tool. Two endodontists acted as independent and calibrated observers. They analyzed each bone defect for volume. The difference between the direct volumetric measurements and the measurements obtained with the CBCT images was statistically assessed using a lack-of-fit test. A correlation study was undertaken using the Pearson product-moment correlation coefficient. Intra- and interobserver agreement was also evaluated.

Results

The results showed a good fit and strong correlation between both volume measurements (ρ > 0.9) with excellent inter- and intraobserver agreement.

Conclusions

Using this software, CBCT proved to be a reliable method in vitro for the estimation of endodontic lesion volumes in bovine jaws. Therefore, it may constitute a new, validated technique for the accurate evaluation and follow-up of apical periodontitis.     

Reliability of different three-dimensional cephalometric landmarks in cone-beam computed tomography: A systematic review

Objectives:Conventional two-dimensional (2D) cephalometric radiography is an integral part of orthodontic patient diagnosis and treatment planning. One must be mindful of its limitations as it indeed is a 2D representation of a vaster three-dimensional (3D) object. Issues with projection errors, landmark identification, and measurement inaccuracies impose significant limitations, which may now be overcome with the advent of cone-beam computed tomography (CBCT). A systematic review of the reliability of different 3D cephalometric landmarks in CBCT imaging was conducted.Materials and Methods:Electronic database searches were administered until October 2017 using PubMed, MEDLINE via OvidSP, EBMR and EMBASE via OvidSP, Scopus, and Web of Science. Google Scholar was used as an adjunctive search tool.Results:Thirteen articles considering CBCT scans of human subjects from preexisting data sets were selected and reviewed. Most of the studies had methodological limitations and were of moderate quality. Because of their heterogeneity, key data from each could not be combined and were reported qualitatively. Overall, in 3D, midsagittal plane landmarks demonstrated greater reliability compared with bilateral landmarks. A minimum number of dental landmarks were reported, although most were recommended for use.Conclusions:Further research is required to evaluate the reliability of 3D cephalometric landmarks when evaluating 3D craniofacial complexes.     

Quantitative analysis of metallic artifacts caused by dental metals: comparison of cone-beam and multi-detector row CT scanners

Objectives  

To quantitatively compare the streak artifacts produced by dental metals in a cone-beam computed tomography (CBCT) device and a multi-detector row computed tomography (MDCT) scanner in relation to metal types and imaging parameters.     

Area and 3-dimensional Volumetric Changes of Periapical Lesions after Root Canal Treatments

Introduction

This study compared the changes in size of periapical lesions after root canal treatment as revealed by periapical radiography (PA) and cone-beam computed tomography (CBCT) imaging using area and 3-dimensional volumetric measurements and assessed the outcome of the treatments based on these parameters.

Methods

Both PA and CBCT scans were taken preoperatively and at recall. In total, 50 teeth (71 roots) with evidence of periapical bone loss on both PA and CBCT images were endodontically treated and followed for 10–37 months. The area and volume of periapical lesions were measured, and changes were presented in the following 4 categories: lesion undetected, lesion reduced in size, lesion unchanged, or lesion enlarged. The McNemar and chi-square tests were used to compare the lesion changes determined by CBCT imaging and PA.

Results

The 4-category diagnosis made using both methods were in agreement in 39 of 71 (54.9%) roots, whereas disagreement was observed in 32 of 71 (45.1%) roots (P < .001). At recall, lesion was absent in 11 of 71 (15.5%) roots on CBCT scans and 32 of 71 (45.1%) roots on PA (P < .001). When success was defined as the absence of a lesion or a reduction in size of a lesion, 55 (77.5%) roots on CBCT imaging showed success and 63 (88.7%) roots on PA (P = .073).

Conclusions

Changes in lesion size after root canal treatment determined with 3-dimensional volumetric CBCT data and 2-dimensional PA data are different. The outcome of root canal treatments determined with PA could be untrue.     

Reliability of 3D dental and skeletal landmarks on CBCT images

Objectives:To quantify reliability of three-dimensional skeletal landmarks and a comprehensive set of dental landmarks in cone-beam computed tomography (CBCT) and to determine the shapes of envelope of error.Materials and Methods:Three judges located 31 skeletal landmarks and 60 dental landmarks on the pre- and posttreatment CBCT images of 22 patients. Landmark error was determined by calculating the distance of deviation of landmark locations around their average. Standard deviation and mean radial spherical error were calculated. Scatterplots were constructed to characterize envelope of error.Results:The midline landmarks of the cranial base were highly reliable. Bilateral skeletal landmarks tended to have larger error than midline landmarks. Among the nonconventional landmarks, fronto-zygomatic suture, condyle, and mental foramen showed relatively high reliability. However, foramen spinosum and temporal fossa showed larger errors. Gonion was the least reliable landmark. Most dental landmarks were located more reliably than skeletal landmarks. The highest reliability was found at incisal edges. Mesiobuccal cusp of first molars also showed high reliability.Conclusions:There were differences in the size and shape of the distributions of errors of different landmarks. Most landmarks showed elongated envelopes. Bilateral structures tended to show greater errors than midline structures. Most dental landmarks were more reliable than skeletal landmarks.     

The effect of voxel size on image reconstruction in cone-beam computed tomography

Objectives  

This study evaluated the effects of changing the voxel size on the resolution and noise of cone-beam computed tomography (CBCT) reconstruction images.     

Cone-beam computed tomography findings of temporomandibular joints with osseous abnormalities

Objective

To evaluate the cone-beam computed tomography (CBCT) findings of temporomandibular joints (TMJs) with osseous abnormalities.

Methods

CBCT images of 88 TMJs in 44 patients with arthrogenic TMJ disorder and 40 normal TMJs of 20 asymptomatic patients were selected for the study. All images were used for evaluation of the condyles (position and width), glenoid fossae (width and depth), and joint spaces (anterior, posterior, and maximum superior). The frequencies of the condylar positions were compared between the two groups using the Chi-square test. The mean values of the remaining CBCT findings were compared between the two groups using the Mann?CWhitney U test.

Results

In the 88 TMJs with osseous abnormalities, a dorsal position of the condyle was most frequently seen (62/88), whereas central and ventral positions of the condyle were seen in two and 24 joints, respectively. The TMJs with osseous abnormalities exhibited a significantly lower mean value for the condyle width and a significantly higher mean value for the anterior joint space than the TMJs without such abnormalities.

Conclusions

Small and dorsally positioned condyles are characteristic CBCT findings of TMJs with osseous abnormalities.     

Evaluation of cephalometric landmark identification on CBCT multiplanar and 3D reconstructions

Objective:To evaluate the reliability of three-dimensional (3D) landmark identification in cone-beam computed tomography (CBCT) using two different visualization techniques.Materials and Methods:Twelve CBCT images were randomly selected. Three observers independently repeated three times the identification of 30 landmarks using 3D reconstructions and 28 landmarks using multiplanar views. The values of the coordinates X, Y, and Z of each point were obtained and the intraclass correlation coefficient (ICC) was calculated.Results:The ICC of the 3D visualization was rated >0.90 in 67.76% and 45.56%, and ≤0.45 in 13.33% and 14.46% of the intraobserver and interobserver assessments, respectively. The ICC of the multiplanar visualization was rated >0.90 in 82.16% and 78.56% and ≤0.45 in only 16.7% and 8.33% of the intraobserver and interobserver assessments, respectively. An individual landmark classification was done according to ICC values.Conclusions:The frequency of highly reliable values was greater for multiplanar than 3D reconstructions. Overall, lower reliability was found for points on the condyle and higher reliability for those on the midsagittal plane. Depending on the anatomic region, the observer must choose the most reliable type of image visualization.     

The Importance of Cone-beam Computed Tomography in the Management of Endodontic Problems: A Review of the Literature

Introduction

To obtain essential information in clinical endodontics, cone-beam computed tomographic (CBCT) imaging can be used in all phases of treatment including diagnosis, treatment planning, during the treatment phase, and through post-treatment assessment and follow-up. The purpose of this article was to review the use of CBCT imaging in the diagnosis, treatment planning, and assessing the outcome of endodontic complications.

Methods

Literature was selected through a search of PubMed electronic databases for the following keywords: tooth root injuries, tooth root radiography, tooth root perforation, tomography, cone-beam computed tomography, endodontic complications, tooth root internal/external resorption, root fractures, and broken instruments. The research was restricted to articles published in English. One hundred twelve articles met the inclusion criteria and were included in this review.

Results

Currently, intraoral radiography is the imaging technique of choice for the management of endodontic disease, but CBCT imaging appears to have a superior validity and reliability in the management of endodontic diagnosis and complications.

Conclusions

Endodontic cases should be judged individually, and CBCT imaging should be considered in situations in which information from conventional imaging systems may not yield an adequate amount of information to allow the appropriate management of endodontic problems. CBCT imaging has the potential to become the first choice for endodontic treatment planning and outcome assessment, especially when new scanners with lower radiation doses will be available.     

Reliability of anatomic structures as landmarks in three-dimensional cephalometric analysis using CBCT

Objective:To identify anatomic structures in three dimensions and examine their reliability to be used as landmarks in a three-dimensional coordinate cephalometric analysis, using cone-beam computerized tomography (CBCT).Materials and Methods:Thirty CBCT images were randomly selected for landmark location. Forty-two anatomic landmarks, which are not included in the traditional cephalometric landmarks, were chosen based on radiographic characteristics that make them pragmatic to mark in the CBCT image slices. The principal investigator marked the full set of landmarks on the software by navigating in the X, Y, and Z axes for every image three times, with each measurement trial being at least 1 week apart. One other investigator also located the landmarks once for each image for reliability purposes. Intraclass correlation coefficients (ICCs) were used to analyze the mean differences in landmark location in all axes.Results:Intra- and interexaminer reliability for x, y, and z coordinates for all landmarks had ICC greater than 0.95 with confidence interval of 0.88–0.99. Mean measurement differences found were <1.4 mm for all landmarks in all three coordinates. Mean measurement error differences obtained in the principal investigator''s trials were primarily <0.5 mm.Conclusion:The most reliable and reproducible landmarks tested for use in CBCT are mental foramina, infraorbital foramina, inferior hamulus, dens axis, foramina transversarium of atlas, medial and lateral condyles of the mandible, superior clinoid processes, and mid-clinoid.     

Comparison of two- and three-dimensional filtering methods to improve image quality in multiplanar reconstruction of cone-beam computed tomography

Objectives  

Two- and three-dimensional (2D and 3D, respectively) filtering methods were examined to improve the accuracy of bone morphology depicted in dental cone-beam computed tomography (CBCT) images. An attempt to improve multiplanar reconstruction (MPR) image quality was carried out by reducing the image noise.     

Characteristics of anatomical landmarks in the mandibular interforaminal region: a cone-beam computed tomography study

Objectives: This study was conducted to assess appearance, visibility, location and course of anatomical landmarks in mandibular interforaminal region using cone-beam computed tomography (CBCT). Study design: A total of 96 CBCT examinations was re-evaluated to exploit anatomical landmarks. The examinations used the Promax 3D CBCT unit. A sole examiner carried out all the measurements. Visibilities of the anatomical landmarks were scored using a four-point rating scale. Results: The mandibular foramen, anterior loop, incisive canal and lingual foramen were observed in 100,84,83,49 % of the images, respectively. The mean size, diameter and width of anterior loop, incisive canal and lingual foramen were obtained 3.54± 1.41, 1.47±0.50 and 0.8 ± 0.09mm, respectively. Conclusion: It is not safe to recommend any definite distance mesially from the mental foramen. The diameter of the canals and foramens should be determined on a case-by-case basis to exploit the appropriate location for each individual. Key words:Anatomical landmarks, cone-beam computed tomography, implant surgery, radiographic evaluation, surgical complications.     

Evaluation of odontogenic maxillary sinusitis using cone-beam computed tomography: three case reports

Introduction

Ten to twelve percent of all cases of maxillary sinusitis derive from odontogenic origin. The purpose of this study was to report the use of cone-beam computed tomography (CBCT) scanning in elucidating dental pathology as an etiology of maxillary sinusitis.

Methods

Intraoral periapical radiographs and CBCT scanning were performed in the evaluation of three patients presenting with pain, sinus congestion, or respiratory complaints. In the first case, extractions of impacted third molar and adjacent nonrestorable tooth were performed. In the second two cases, endodontic therapy was done. Radiologic follow-up with CBCT scanning or medical computed tomography scanning was performed 6 to 12 months after dental procedures were performed.

Results

All three patients presented with severe sinusitis that resolved after appropriate dental treatment. The first patient also showed marked improvement of chronic bronchitis after completion of dental treatment. In all patients, complete or near total resolution of sinusitis, including eradication of mucous retention cyst, was confirmed by post-treatment CBCT or computed tomography scanning.

Conclusions

These cases show the utility of CBCT scanning in evaluating patients presenting with concurrent sinus and dental complaints. In these three patients, maxillary sinusitis of odontogenic origin responded well to the eradication of dental etiology.     

Accuracy of cone-beam computed tomography to assess the configuration and extent of ligature-induced peri-implantitis defects. A pilot study

Purpose

This is a pilot study which aims to evaluate the accuracy of cone-beam computed tomography (CBCT) to assess the configuration and extent of ligature-induced peri-implantitis defects.

Materials and methods

Radiographic evaluation of advanced ligature-induced peri-implantitis defects (n?=?9) in canine was performed using CBCT (central cross-sections) and compared with the corresponding histomorphometrical measurements of the respective site serving as a validation method. Deviations were calculated for the supracrestal (SC), and intrabony (IC) defect components, as well as defect width (DW) assessed at both vestibular (v) and oral (o) aspects.

Results

Mean differences between CBCT and histological analyses were ?0.53?±?1.48?mm (SC), +0.49?±?1.18?mm (IC), and +0.18?±?0.54?mm (DW) at vestibular aspects, and ?0.13?±?0.44?mm (SC), ?0.05?±?0.62?mm (IC), and +0.15?±?0.48?mm (DW) at the oral aspects (P?>?0.05; paired t test, respectively).

Conclusion

CBCT may represent an accurate diagnostic tool to estimate the histological extent of advanced peri-implantitis defects.     

Clinician-centered Outcomes Assessment of Retreatment and Endodontic Microsurgery Using Cone-beam Computed Tomographic Volumetric Analysis

Introduction

Outcomes assessment of retreatment and endodontic microsurgery (EMS) are traditionally based on clinical findings and radiographs. The purpose of this study was to assess the volumetric change of periapical radiolucencies (PARLs) by cone-beam computed tomographic (CBCT)-based analysis in retreatment and EMS cases.

Reproducibility of three-dimensional cephalometric landmarks in cone-beam and low-dose computed tomography

Objectives

The purpose of this study is to compare the reproducibility of three-dimensional cephalometric landmarks on three-dimensional computed tomography (3D-CT) surface rendering using clinical protocols based on low-dose (35-mAs) spiral CT and cone-beam CT (I-CAT). The absorbed dose levels for radiosensitive organs in the maxillofacial region during exposure in both 3D-CT protocols were also assessed.

Materials and methods

The study population consisted of ten human dry skulls examined with low-dose CT and cone-beam CT. Two independent observers identified 24 cephalometric anatomic landmarks at 13 sites on the 3D-CT surface renderings using both protocols, with each observer repeating the identification 1 month later. A total of 1,920 imaging measurements were performed. Thermoluminescent dosimeters were placed at six sites around the thyroid gland, the submandibular glands, and the eyes in an Alderson phantom to measure the absorbed dose levels.

Results

When comparing low-dose CT and cone-beam CT protocols, the cone-beam CT protocol proved to be significantly more reproducible for four of the 13 anatomical sites. There was no significant difference between the protocols for the other nine anatomical sites. Both low-dose and cone-beam CT protocols were equivalent in dose absorption to the eyes and submandibular glands. However, thyroid glands were more irradiated with low-dose CT.

Conclusions

Cone-beam CT was more reproducible and procured less irradiation to the thyroid gland than low-dose CT.

Clinical relevance

Cone-beam CT should be preferred over low-dose CT for developing three-dimensional bony cephalometric analyses.     

Evaluation of the maxillary third molar position and its relationship with the maxillary sinus: a CBCT study

Objectives

The present study investigated the position and relationship of the maxillary third molars to the maxillary sinus. These molars were detected to have a close relationship with the maxillary sinus based on panoramic images, using cone-beam computed tomography (CBCT).

Methods

This retrospective study evaluated 162 impacted third molars from 100 patients that showed a superimposed relationship between the maxillary sinus and third molars on panoramic images obtained from CBCT. CBCT images were used to assess the horizontal (buccopalatal) and vertical positions of the maxillary sinus relative to the maxillary third molars, proximity of the roots to the sinus, and angulation and depth of the third molars. The associations among the angulation, depth of third molars, and horizontal and vertical positions of the maxillary sinus relative to the third molar findings were examined using Chi square tests.

Results

Based on the winter classification, the most frequent tooth position was vertical (59.9 %), followed by mesioangular (14.2 %), distoangular (9.9 %), and others. Most impacted teeth were at the level between the occlusal and cervical levels of the adjacent second molar. Regarding the relationships of the maxillary third molars with the maxillary sinus examined on CBCT, vertical type III (buccal root related with maxillary sinus) (34 %) and horizontal type 2 (maxillary sinus located between roots) (64.8 %) were seen most frequently.

Conclusions

The relationship between the maxillary sinus and third molar roots should be considered during extraction. When a risk of sinus perforation is predicted in an extraction, a presurgical CBCT examination could be valuable.

     

Observation of the retromolar foramen and canal of the mandible: a CBCT and macroscopic study

Objectives  

The retromolar foramen (RMF) is an anatomical structure on the alveolar surface of the retromolar area. This foramen runs consecutive to the retromolar canal (RMC), which diverges from the mandibular canal. It is important to confirm the RMF and canal locations prior to surgical procedures, such as extraction of an impacted molar and bone harvesting as a donor site for bone graft surgery. This aim of this study was to investigate the RMF in Japanese cadaver mandibles using cone-beam computed tomography (CBCT) images and anatomical observations.