Influence of voxel size in the diagnostic ability of cone beam tomography to evaluate simulated external root resorption

An Automatic Grading System for Orthodontically Induced External Root Resorption Based on Deep Convolutional Neural Network

Orthodontically induced external root resorption (OIERR) is a common complication of orthodontic treatments. Accurate OIERR grading is crucial for clinical intervention. This study aimed to evaluate six deep convolutional neural networks (CNNs) for performing OIERR grading on tooth slices to construct an automatic grading system for OIERR. A total of 2146 tooth slices of different OIERR grades were collected and preprocessed. Six pre-trained CNNs (EfficientNet-B1, EfficientNet-B2, EfficientNet-B3, EfficientNet-B4, EfficientNet-B5, and MobileNet-V3) were trained and validated on the pre-processed images based on four different cross-validation methods. The performances of the CNNs on a test set were evaluated and compared with those of orthodontists. The gradient-weighted class activation mapping (Grad-CAM) technique was used to explore the area of maximum impact on the model decisions in the tooth slices. The six CNN models performed remarkably well in OIERR grading, with a mean accuracy of 0.92, surpassing that of the orthodontists (mean accuracy of 0.82). EfficientNet-B4 trained with fivefold cross-validation emerged as the final OIERR grading system, with a high accuracy of 0.94. Grad-CAM revealed that the apical region had the greatest effect on the OIERR grading system. The six CNNs demonstrated excellent OIERR grading and outperformed orthodontists. The proposed OIERR grading system holds potential as a reliable diagnostic support for orthodontists in clinical practice.

Introducing a new auto edge detection technique capable of revealing cervical root resorption in CBCT scans with pronounced metallic artifacts

Cervical resorption is a serious threat to the longevity of the teeth. In this study, the Canny edge-detection algorithm was applied on CBCT images to compare the accuracy of original and Canny views for diagnosing cervical resorption in endodontically treated teeth. Intracanal metallic posts were inserted in 60 extracted teeth being randomly divided into three groups: control, 0.5 mm, and 1 mm cervical resorption. CBCT scans of the teeth were presented to three observers in both original and Canny formats with the accuracy being determined by receiver operating characteristic (ROC) analysis. The DeLong test was used for paired comparisons with the significance level set at 0.05. The highest accuracy belonged to Canny images in 1 mm resorption, followed by Canny images in 0.5 mm resorption, original images in 1 mm resorption, and original images in 0.5 mm resorption, respectively. The Canny images were significantly more accurate in the diagnosis of 0.5 mm (p < 0.001) and 1 mm (p = 0.009) resorption. Application of the Canny edge-detection algorithm could be suggested as a new technique for facilitating the diagnosis of cervical resorption in teeth that are negatively affected by metallic artifacts.

Cone-beam computed tomography in endodontics: from the specific technical considerations of acquisition parameters and interpretation to advanced clinical applications

The implementation of imaging methods that enable sensitive and specific observation of anatomical structures has been a constant in the evolution of endodontic therapy. Cone-beam computed tomography (CBCT) enables 3-dimensional (3D) spatial anatomical navigation in the 3 volumetric planes (sagittal, coronal and axial) which translates into great accuracy for the identification of endodontic pathologies/conditions. CBCT interpretation consists of 2 main components: (i) the generation of specific tasks of the image and (ii) the subsequent interpretation report. A systematic and reproducible method to review CBCT scans can improve the accuracy of the interpretation process, translating into greater precision in terms of diagnosis and planning of endodontic clinical procedures. MEDLINE (PubMed), Web of Science, Google Scholar, Embase and Scopus were searched from inception to March 2023. This narrative review addresses the theoretical concepts, elements of interpretation and applications of the CBCT scan in endodontics. In addition, the contents and rationale for reporting 3D endodontic imaging are discussed.

Application of metal artifact reduction algorithm for CBCT diagnosis of temporary anchorage device-tooth root contact: inadequate to reduce false-positive rate

OBJECTIVES

It was recently found that when cone beam computed tomography (CBCT) was used to examine temporary anchorage device (TAD)-tooth root contact, it tends to yield high false-positive (FP) diagnoses. This study investigated whether application of a metal artifact reduction (MAR) algorithm or reducing CBCT scan voxel-size can remediate this problem.

METHODS

18 fresh pig cadaver mandibles underwent TAD placement bilaterally at first molar lingual furcation regions. CBCT scans were taken under varied MAR (absence, presence) and voxel-size (400 µm, 200 µm) settings. Then, TADs were removed and a micro-CT scan (27 µm voxel-size) of the TAD placement site was performed. Three raters, blinded of CBCT scan setting, independently diagnosed whether TADs were in contact with roots. The reliability and accuracy of CBCT diagnoses using micro-CT as the gold-standard were statistically examined.

RESULTS

Generally, CBCT diagnoses had intrarater (Cohen's κ: 0.54-1) and interrater (Fleiss' κ: 0.73-0.81) reliability, within the moderate to excellent range, which did not vary with MAR setting or scan voxel-size. For diagnostic accuracy, FP rate among all raters was mostly in the 15-25% range and did not change with MAR or scan voxel-size settings (McNemar tests, p > 0.05) while false-negative rate was relatively minimal and only occurred to one rater (9%).

CONCLUSIONS

When using CBCT to diagnose possible TAD-root contact, applying a currently available Planmeca MAR algorithm or reducing CBCT scan voxel-size from 400 µm to 200 µm may not decrease FP rate. Further optimization of the MAR algorithm for this purpose may be needed.

Effect of field of view and voxel size on CBCT-based accuracy of dynamic navigation in endodontic microsurgery: an in vitro study

INTRODUCTION

This study aimed to evaluate the influence of field of view (FOV) and voxel size on the accuracy of dynamic navigation (DN)-assisted endodontic microsurgery (EMS).

METHODS

Nine sets of maxillary and mandibular three-dimensional-printed jaw models composed of 180 teeth were divided into nine groups with different FOVs (80 × 80 mm, 60 × 60 mm, and 40 × 40 mm) and voxel sizes (0.3, 0.16, and 0.08 mm). The endodontic DN system was used to plan and execute the EMS. The accuracy of the DN-EMS was represented by the platform deviation, end deviation, angular deviation, resection angle, and resection length deviation. Statistical analyses were performed using SPSS 24.0, and the significance level was set at p < 0.05.

RESULTS

The average platform, end, angular, resection angle, and resection length deviation were 0.69 ± 0.31 mm, 0.93 ± 0.44 mm, 3.47 ± 1.80°, 2.35 ± 1.76°, and 0.41 ± 0.29 mm, respectively. No statistically significant differences in accuracy were observed between the nine FOV and voxel size groups.

CONCLUSION

FOV and voxel size did not appear to play an important role in the accuracy of DN-EMS. Considering the image quality and radiation dose, it is reasonable to select a limited FOV (such as 40 × 40 mm and 60 × 60 mm) to cover only the registration device, involved teeth, and periapical lesion. The voxel size should be selected according to the required resolution and CBCT units.

Diagnostic accuracy of paranasal sinus measurements on multislice computed tomography for sex estimation: A systematic review, meta-analysis, and meta-regression

This systematic review aimed to answer the question, "Are paranasal measurements obtained with multislice computed tomography able to accurately estimate sex?" This PROSPERO-registered systematic review included six databases and gray literature. Meta-analysis of linear and volumetric data was performed using a random-effects model, mean differences (MDs), and inverse variance. The QUADAS-2 tool-related risk of bias (RoB) and certainty evidence (GRADE approach) were assessed. A total of 1651 articles were initially selected from the main electronic databases for title and abstract screening. After removing duplicates and studies that did not meet the inclusion criteria, 18 studies were eligible for the meta-analysis. The screened studies included 2507 computed tomography of non-pathologic paranasal sinuses of adults aged between 18 and 40 years. Frontal sinus (FS) width (-4.89 mm; p < 0.00001) and maxillary sinus (MS) height (-3.73 mm; p < 0.00001) showed the greatest MD between females and males. Regarding volume, the MD was significant (p < 0.00001) in both paranasal sinuses (-3.01 and -1.04 cm³ , respectively). The best sensitivity (ability to identify males) and specificity (ability to identify females) were found for the anteroposterior (72.3%) and intermaxillary (69%) MS distances, respectively. In general, all studies exhibited low RoB and applicability concerns. The certainty of the evidence was categorized as very low to moderate. Both paranasal sinuses were shown to be dimorphic structures, which could be valuable tools for forensic identification using the FS width and MS anteroposterior distance measurements. However, heterogeneity among studies must be considered.

External root resorption evaluated by CBCT 3D models superimposition

Introduction:

The literature reports the association of external root resorption (ERR) with orthodontic movement. In cases of premolars extractions, orthodontic movement of anterior teeth is usually quite expressive, which are precisely the most susceptible teeth to suffer from ERR.

Objective:

The aim of this study was to assess the root morphology of maxillary canines and incisors in patients submitted to four premolar extraction and orthodontic retraction of the anterior teeth, by means of 3D surface models superimposition and mapping.

Methods:

The sample consisted of six adult patients, five female and one male, with a mean age of 23.5 ± 6.5 years, who underwent orthodontic treatment. All patients presented bimaxillary dental protrusion, with indication of maxillary and mandibular first premolar extractions, followed by the retraction of anterior teeth and space closure. Cone beam CT scans were performed before the beginning of the treatment (T₀) and right after space closure (T₁). 3D models were built at both times and superimposed to identify the root changes for the given period.

Results:

All average differences were close to zero and, even when evaluating the extreme values, the observed changes were always smaller than the accuracy of the CBCT.

Conclusion:

A mild resorption trend was observed, although it was not clinically significant, with values lower than the tomography accuracy.

Influence of Cone-beam Computed Tomography in clinical decision-making among different specialists in External Cervical Resorption lesions: a before-after study

INTRODUCTION

Inadequate management of external cervical resorption (ECR) lesions may impact the treatment outcome. This study aimed to ascertain the influence of cone-beam computed tomography (CBCT) in clinical decision-making choices in cases of ECR among dentistry specialists (endodontics, prosthodontics, oral surgery, periodontics orthodontics, and general dentistry). A secondary objective was to evaluate the self-reported level of difficulty in choosing a treatment plan before and after viewing the CBCT images.

METHODS

Sixty examiners from different specialties were chosen to evaluate 12 cases of ECR lesions. Each case included clinical photographs, digital periapical (PA) radiographs, and a small-volume CBCT scan. In the first assessment, the examiners were given all the relevant information of each case, except the CBCT scan. Each examiner was asked to select 1 of the proposed treatment options and assess the difficulty of decision making. Four weeks later, the examiners randomly reviewed the same 12 cases with additional information from the CBCT data.

RESULTS

After the CBCT evaluation, the clinicians changed their treatment plan in 72.2% of the cases (P < .05). The self-reported level of difficulty in choosing a treatment changed in all groups after evaluating the CBCT scans (P< .05). After viewing the CBCT scan, the extraction option increased significantly in all groups (P < .05).

CONCLUSIONS

CBCT scan had a significant impact on clinical decision-making in cases of ECR evaluated by different specialists.

Safe sites for orthodontic miniscrew insertion in the infrazygomatic crest area in different facial types: A tomographic study

INTRODUCTION

Temporary skeletal anchorage devices (TSADs) are used to obtain skeletal anchorage for orthodontic treatment. Their insertion in the infrazygomatic crest (IZC) allows efficient orthodontic mechanics. Different facial types have different bone configurations. We aimed to evaluate the differences in bone thicknesses in the IZC area among patients of each facial type to determine a safe zone for TSAD insertion.

METHODS

For this retrospective study, 86 cone-beam computed tomography (CBCT) scans were divided into 3 groups according to the facial type: group I, 24 CBCT scans of hyperdivergent patients; group II, 30 scans of neutral patients; and group III, 32 scans of hypodivergent patients. The buccal alveolar bone thickness was measured in 6 zones between the second premolar and distal root of the second molar, 5, 7, 9, and 11 mm apical to the alveolar crest.

RESULTS

The IZC areas with minimum thickness for TSAD insertion follows: group I, between first and second molars at 11 mm from the alveolar crest, mesial root of the second molar at 9 mm from the crest, and distal root of the second molar at 11 mm from the crest; groups II and III, between first and second molars at 11 mm from the crest and mesial root of the second molar at 11 mm from the crest.

CONCLUSIONS

The safe zones for IZC miniscrew insertion are located 11 mm from the alveolar crest between the maxillary first and second molars and on the mesial root of the second molar for all the 3 facial types.

Effects of Exposure Parameters and Voxel Size for Cone-Beam Computed Tomography on the Image Matching Accuracy with an Optical Dental Scan Image: An In Vitro Study

This study is aimed at assessing the effects of exposure parameters and voxel size for cone-beam computed tomography (CBCT) on the image matching accuracy with an optical dental scan image. CBCT and optical scan images of a dry human mandible were obtained. Different CBCT settings were used: tube voltage, 60, 80, and 100 kVp; tube current, 6 and 8 mA; and voxel size, 100, 200, and 300 μm. Image matching between the CBCT and optical scan images was performed using implant planning software by dental professionals (n = 18). The image matching accuracy in each combination of CBCT settings was evaluated by assessing the linear discrepancy between the three-dimensionally reconstructed radiological image and the registered optical scan image using an image analysis software program. The Kruskal-Wallis test and a post hoc Mann–Whitney U test with Bonferroni correction were used to compare the accuracy of image registration between the groups (α = 0.05). Overall, the image matching accuracy was not significantly different between tube voltage and current settings; however, significantly higher image registration errors were found at the combination of 100 kVp tube voltage/8 mA tube current (F = 8.44, P < 0.001). Changes in voxel sizes did not significantly interfere with the image registration results. No interaction was found among voltage, current, and voxel size in terms of image registration accuracy (F = 2.022, P = 0.091). Different exposure parameter settings in tube voltage and tube current did not significantly influence the image matching accuracy between CBCT and optical dental scan images; however, a high radiation dose could be inappropriate. The image matching accuracy was not significantly affected by changing the voxel sizes of CBCT.

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.

Influence of voxel size on cone beam computed tomography artifacts arising from the exomass

OBJECTIVES

The objective of this study was to evaluate the influence of voxel size on artifacts arising from the exomass in cone beam computed tomography (CBCT).

STUDY DESIGN

An imaging phantom was scanned using 2 CBCT units, each adjusted to 2 voxel sizes: 0.2 and 0.3 mm. From 1 to 3 metal inserts of titanium, cobalt-chromium, or amalgam were placed in the exomass and additional CBCT scans were acquired. Mean voxel gray values were obtained from 16 homogeneous areas of the phantom and averaged, and the standard deviation was calculated to obtain voxel gray value variability. The data were analyzed using 2-way analysis of variance, Tukey, and Dunnett tests (α =.05).

RESULTS

Overall, mean voxel gray values and voxel gray value variability did not differ significantly between CBCT scans obtained with voxel sizes of 0.2 and 0.3 mm for either CBCT model tested (P > .05). Despite some exceptions in which significant differences were observed between the 2 voxel sizes (P < .05), the mean voxel gray values and voxel gray value variability resulting from different metal compositions and, in most situations, for different numbers of metal inserts in the exomass were not affected.

CONCLUSION

Voxel size has little influence on exomass-related CBCT artifacts.

Identification of mandibular canal in cone beam computed tomography plane with different voxel sizes

Introduction

Identification of the mandibular canal (MC) is essential before any lower jaw surgical procedures. Understanding the anatomical variations of the MC is essential for preventing postoperative complications.

Objectives

We assessed the observer agreement for identifying the MC in cone-beam computed tomography (CBCT) images and to study the effect of changing the voxel size on such agreements.

Material and methods

We obtained images of mandibles from ten dry skulls using a water phantom with two voxels: 0.18 and 0.3 mm. The identification of the MC was made in five sites bilaterally in each mandible by two examiners.

Results

A total of 82 sites were included. Differences in measurements between images obtained with each scanning protocol and the reference images were calculated using descriptive statistics. There was an agreement between the two examiners in identifying the MC in CBCT images. No significant differences were found for identifying the MC when the voxel sizes were changed. There was a strong correlation coefficient between the two examiners for both voxel sizes (p < 0.001).

Conclusion

This study showed that voxel size, in the range from 0.18 to 0.3 mm, has no direct effect on the identification of the MC.

Imaging diagnosis of external root resorption in replanted permanent teeth

The present study aimed to evaluate the performance of cone beam computed tomography (CBCT) and digital periapical radiographs (PR) in diagnosing external root resorption (ERR) in human permanent teeth replanted after traumatic avulsion. The samples comprised 39 permanent maxillary incisors replanted after traumatic avulsion. Digital PR and CBCT images were taken from each tooth and independently examined by 2 calibrated examiners to assess the ERR activity regarding type and extension. The degrees of agreement between both imaging examinations were determined by the mean global agreement index using SPSS software. The two imaging examinations diverged greatly in the diagnosis of the type of ERR since CBCT identified more cases as inflammatory ERR and PR as replacement ERR. A discordance level of 69.2% was observed between the two methods in the diagnosis of the type of ERR when CBCT for mesial and distal (MD) surfaces was considered and 61.5% when CBCT for mesial, distal, buccal and lingual (MD/BL) was considered. Likewise, CBCT and PR differed regarding the ERR index. PR examinations classified most cases as moderate or severe (69.2%), while CBCT examinations classified more cases as mild either in the MD surfaces analysis (41.4%) or in the analysis of the MD-BL surfaces (51.3%). In conclusion, the present results highlight a discrepancy between CBCT and digital PR performance in the diagnosis of different types and extent of ERR in replanted teeth.

Comparison of CBCT with different voxel sizes and intraoral scanner for detection of periodontal defects: an in vitro study

OBJECTIVES

This study aimed to compare the diagnostic accuracy of cone beam CT (CBCT) units with different voxel sizes with the digital intraoral scanning technique in terms of the detection of periodontal defects.

METHODS AND MATERIALS

The study material comprised of 12 dry skulls with maxilla and mandible. Artificial defects were created on teeth separately using burs randomly on dry skulls. In total 46 dehiscences, 10 fenestrations, 17 furcations, 12 wall defects and 13 without periodontal defect were used in the study. Each tooth with and without defects was imaged at various vertical angles using each of the following modalities: a Veraviewepocs 3D R100 CBCT device and a 3D Shape TRIOSㄾ Color P13 Shade Intraoral Scanner.

RESULTS

The κ values for interobserver agreement between observers ranged between 0.29 and 0.86 for the CBCT 10 × 8 cm field of view (FOV) with 0,160 mm3 voxel size; 0.35 and 1 for the CBCT 8 × 8 cm FOV with 0,125 mm3 voxel size; and 0.30 and 1 of intraoral scans. The κ values for detecting defects on anterior teeth were the least, following premolar and molar teeth both CBCT and intraoral scanning.

CONCLUSIONS

Smaller voxel sizes and smaller CBCT FOV has the highest sensitivity and diagnostic accuracy for detecting various periodontal defects among the scanner modalities examined.

ADVANCES IN KNOWLEDGE

Adequate evaluation of the condition of the alveolar bone and periodontal tissues is important for the diagnosis, treatment, and prognosis of periodontal disease. Limited examination methods, such as palpation, inspection, and periodontal probe examination, may provide insufficient information for the diagnosis of periodontal diseases.

Volumetric measurements of mandibular incisor root resorption following Forsus FRD EZ2 and Bionator appliance treatment using cone-beam computed tomography: A preliminary study

Objectives:

Root resorption is one of the frequently encountered problems in orthodontic treatments. The effects of functional appliances on root resorption have not been clearly demonstrated. The aim of this study was to compare volumetric root resorption of mandibular incisors after Bionator and Forsus appliance treatment using cone-beam computed tomography (CBCT).

Materials and Methods:

The study sample (n = 30) was selected from Class II div. 1 mandibular retrognathia patients treated with the Bionator and Forsus appliances. The first CBCT scans were taken before Bionator use and after 6 months. In the Forsus group, the first CBCT scans were taken before Forsus appliance use and after an overcorrected Class I relationship was obtained. The mean treatment time with the Forsus appliance was 5 ± 1.2 months. Mimics software was used for segmentation and volumetric measurements of mandibular incisor teeth root resorption.

Results:

In the Bionator group, statistically significant root volume loss was not found. In the Forsus group, the differences between before and after the treatment were not statistically significant for teeth 41, 31, and 32 (P > 0.05), whereas the difference was statistically significant for the lower right second incisor (P < 0.002). The percentage of volume loss (%) and root volume loss (mm3) was not statistically significant between groups.

Conclusions:

Following functional treatment with the Bionator and Forsus, statistically significant difference was not found between groups for mandibular incisor root resorption.

Diagnostic efficacy of different cone beam computed tomography scanning protocols in the detection of chemically simulated external root resorption

OBJECTIVES

The aim of this study was to evaluate the efficacy of different high-resolution cone beam computed tomography protocols in the diagnosis of chemically simulated external root resorption (ERR).

STUDY DESIGN

ERR was simulated in 3 sizes by using an acid decalcification protocol in the cervical, middle, and apical thirds of 30 single-rooted premolars. Four scans of each tooth were acquired with different voxel sizes: 0.080, 0.085, 0.120, and 0.133 mm. The images were analyzed by 2 blinded evaluators for the presence of ERR. The evaluation of diagnostic performance was based on receiver operating characteristic (ROC) curve analysis.

RESULTS

No statistically significant differences were found in the detection of ERR with regard to lesion sizes or the different root thirds. Areas under the ROC curve were 0.901, 0.892, 0.887, and 0.767 for voxel sizes of 0.080, 0.085, 0.120, and 0.133 mm, respectively. Voxel sizes of 0.080 and 0.085 mm presented significantly larger areas under the ROC curve compared with the voxel size of 0.133 mm. There were no statistically significant differences among the protocols with the use of voxel sizes of 0.080, 0.085, and 0.120 mm.

CONCLUSIONS

Cone beam computed tomography examinations with higher-resolution protocols demonstrated better performance in the diagnosis of ERR. Further investigations using simulations that more closely resemble the actual ERR process are warranted.

Effect of Resolution and Bit Depth on Inferior Alveolar Canal Visualization on Exported Mandibular Cone-Beam Computed Tomography Images

PURPOSE

Cone-beam computed tomography (CBCT) is commonly requested before dental implant treatment for the anatomic assessment of the inferior alveolar canal (IAC) to prevent its neurovascular content from being traumatized. CBCT images can be saved in different types of resolutions and bit depths; these parameters may significantly affect the diagnostic accuracy of images. This study aimed to assess the effect of resolution and bit depth on IAC visualization on exported mandibular CBCT images.

MATERIALS AND METHODS

Forty-one mandibular CBCT images of differing image resolutions and voxel sizes (0.16, 0.32, and 0.48 mm) and differing bit depths (12 and 15) were exported from a software program as a single file. Two observers evaluated the cross-sectional images in terms of IAC visibility using a 3-point scale (good, moderate, and poor). Disagreements were resolved by including a third observer, and the highest agreement was recorded.

RESULTS

Study interobserver agreement was acceptable (84.2%) for IAC observation. The percentage of IAC observation was from 84.1 to 100% with the 12- and 15-bit depths, with a constant image resolution of 0.16 and 0.32 mm, respectively. A significant difference (from 19.5 to 48.8%) was noted between the 2 bit depths in the percentage of good IAC visualization with a constant resolution of 0.48 mm. Reduction in the image resolution to 0.48 mm showed a significant difference (19.5 to 100%) between the 12- and 15-bit depths in good IAC visualization.

CONCLUSIONS

Exporting the mandibular CBCT images with 0.32 mm of resolution and a 12-bit depth will produce good and moderate radiographic IAC observation with the benefit of a smaller file size.

The anatomical relationship between the roots of erupted permanent teeth and the mandibular canal: a systematic review

PURPOSE

This study reviewed the literature on the position of the mandibular canal (MC) relative to the root apices (RA) of neighbouring teeth using cone beam computed tomography (CBCT).

METHODS

The authors searched the PubMed, Scopus, EBSCO Dentistry and Oral Sciences Source, Cochrane and Lilacs databases for relevant English-language articles with no year limitations published through January 25, 2018.

RESULTS

The search identified 888 articles, 12 of which met the inclusion criteria. Three groups were found based on the measuring method: the shortest distance from the RA to the MC, the vertical distance from the RA to the MC, or the distance from the RA to the superior cortical bone of the MC. In the first and second groups, the shortest distances to the canines, first premolars, second premolars, first molars, second molars, and third molars were 3.8 mm, 4.76 mm, 1.65 mm, 1.23 mm, 0.64 mm, and 1.28 mm, respectively. In the third group, the shortest distances to the second premolars, first molars, and second molars were 2.71 mm, 3.82 mm, and 1.4 mm, respectively.

CONCLUSIONS

The distance from the MC to the RA was generally shorter in females and younger people, with decreasing distances in patients over 60 years old, and depended on the tooth type.

TRIAL REGISTRATION

The protocol for this systematic review was registered on PROSPERO (CRD42018085478).

Accuracy of High- and Low-Resolution Cone-Beam Computed Tomographic Scans in the Detection of Impacted Tooth-Induced External Root Resorption: An Ex-Vivo Study

Objectives:

Cone-beam computed tomography (CBCT) is used in diagnostic situations, as well as tooth impaction and its complications. A possible sequela of tooth impaction is resorption of adjacent teeth, complicating the treatment plans. This study aimed to determine the diagnostic accuracy of high- and low-resolution CBCT scans in the detection of external root resorptions (ERRs), caused by an adjacent impacted tooth in the cementoenamel junction (CEJ), mid-root, and apical areas.

Materials and Methods:

Forty-five intact single-rooted teeth were divided into three groups of 15. Each group was dedicated to each zone of the root. Slight, moderate, and severe ERRs were formed, and CBCT scans were taken before and after the formation of ERRs. The diagnostic accuracy was assessed, and the Proportion test was used to compare the results.

Results:

The statistical analyses of high- and low-resolution images showed a significant difference (P<0.05), which implies the higher accuracy of high-resolution images. The highest diagnostic accuracy among different zones was related to the mid-root, and the lowest was related to the apical zone. In terms of the size of ERRs, the diagnostic accuracy was the lowest for slight ERRs.

Conclusion:

The most reliable and accurate diagnostic mode was found in high-resolution images, in the mid-root zone, and with severe ERRs. The lowest diagnostic accuracy was found in low-resolution images, in the apical zone, and with slight ERRs.

Investigation using cone beam computed tomography analysis, of radicular grooves and canal configurations of mandibular premolars in a Turkish subpopulation

OBJECTIVE

To conduct an in vivo evaluation of prevalence of root canal configurations, lengths of C-shaped canals, prevalence and depths of radicular grooves (RGs), in mandibular first and second premolars in a Turkish subpopulation using cone beam computed tomography (CBCT).

MATERIALS AND METHODS

CBCT images of 327 first and 264 second premolars were included. Canal configurations, locations, lengths, and types of C-shaped canals, and RGs were evaluated on CBCT images. Data were statistically analyzed (P < 0.05).

RESULTS

First and second premolars were classified as follows: type I, (83.8%, 97.72%); type V, (12.22%, 0.76%); type III, (3.06%, 0.76%); and other types. RGs were exhibited by 14.68% of first and 2.27% of second premolars (P < 0.05). Incidence of complex canals (types III, V and other types, 89.8%) in first premolars with RGs was significantly higher versuswithout RGs (P < 0.05). C-shaped configuration was exhibited by 4.58% of first (80% semilunar-type), and 1.13% of second premolars (P < 0.05). All first premolars with C-shaped canals showed RGs and complex canals.

CONCLUSIONS

Complex canals and RGs frequently co-exist in mandibular premolars. C-shaped canals are not common in mandibular premolars, and mostly located in middle thirds. Type V is the most prevalent complex canal configuration in first premolars, and frequently associated with a C-shaped semilunar-type anatomy.

Outcome of periodontal–orthodontic treatment in subjects with periodontal disease. Part II: a CBCT study of alveolar bone level changes

Aim

To examine alveolar bone level (ABL) changes before (T1) and after (T2) orthodontic treatment (OT) in subjects with periodontal disease.

Methods

The study included 50 subjects with periodontal disease. All patients received subgingival debridement following baseline examination. Control group patients received final periodontal treatment before the start of OT. For the test group patients final periodontal treatment was performed simultaneous to OT. OT was performed with a straight-wire appliance. Micro-implants or temporary crowns on implants were used for posterior anchorage when needed. ABL measurements of 3821 tooth surfaces were performed on cone beam computed tomography images.

Results

No difference was observed between mean ABL at T1 and T2. ABL remained unchanged on 69 per cent of surfaces. A mean of 15.6 (SD 7.4) per cent of surfaces experienced ABL gain, and a mean of 15.1 (SD 7.5) per cent was found with ABL loss. Small significant median ABL difference was observed on mesial and distal surfaces (P < 0.001). A significant difference was found between median ABL changes on mesial/distal in comparison to buccal/lingual surfaces (P < 0.01). Significantly more buccal (17.9 %) and lingual (18.5 %) surfaces experienced ABL loss when compared with mesial (11.3 %) and distal (12.0 %) surfaces (P < 0.001). Significant difference was found in the median ABL change of intruded (0.5 (IQR 0.94) mm) and non-intruded (−0.4 (IQR 1.07) mm) maxillary incisors (P = 0.04). Significant median ABL gain was found on the lingual surface of maxillary incisors, which were retroclined more than 8.6 degree and intruded more than 1.6 mm.

Conclusions

ABL changes after periodontal–orthodontic treatment in patients with periodontal disease were small. ABL gain was more observed on mesial and distal surfaces and ABL loss on buccal and lingual surfaces. Larger orthodontic movements of maxillary incisors influenced ABL gain.

The impact of different voxels and exposure parameters of CBCT for the assessment of external root resorptions: A phantom study

This study aimed to compare the effectiveness of the different voxel sizes and imaging parameters of cone beam computed tomography (CBCT) on the determination of external root resorption (ERR). ERRs were created in coronal, middle and apical regions. Depths (0.62-0.73 mm) and diameters (0.68-0.81 mm) of ERRs were measured using a digital calliper. Images were obtained in 0.125, 0.2, 0.25, 0.3 and 0.4 mm³ voxel sizes and at different currents. Data were analysed using Friedman and Wilcoxon signed-rank tests at a level of P < 0.05. There was a difference between the parameters in determining the size of the ERR in coronal and middle regions (P < 0.05), but there was no difference in the apical region (P > 0.05). The change in current and exposure time did not make a difference in determining the dimensions of the ERRs (P > 0.05). Some voxel dimensions were more reliable in determining the depth and diameter of ERR in the coronal and middle region.

Factors affecting modulation transfer function measurements in cone-beam computed tomographic images

Purpose

This study was designed to investigate the effects of voxel size, the oversampling technique, and the direction and area of measurement on modulation transfer function (MTF) values to identify the optimal method of MTF measurement.

Materials and Methods

Images of the wire inserts of the SedentexCT IQ phantom were acquired, and MTF values were calculated under different conditions (voxel size of 0.1, 0.2, and 0.3 mm; 5 oversampling techniques; simulated pixel location errors; and different directions and areas of measurement). The differences in the MTF values across various conditions were evaluated.

Results

The MTF 10 values showed smaller standard deviations than the MTF 50 values. Stable and accurate MTF values were obtained in the 0.1-mm voxel images. In the 0.3-mm voxel images, oversampling techniques of 11 lines or more did not show significant differences in MTF values depending on the presence of simulated location errors. MTF 10 values showed significant differences according to the direction and area of the measurement.

Conclusion

To measure more accurate and stable MTF values, it is better to measure MTF 10 values in small-voxel images. In large-voxel images, the proper oversampling technique is required. MTF values from the radial and tangential directions may be different, and MTF values vary depending on the measured area.

Accuracy and Reliability of Root Crack and Fracture Detection in Teeth Using Magnetic Resonance Imaging

INTRODUCTION

Magnetic resonance imaging (MRI) has the potential to aid in determining the presence and extent of cracks/fractures in teeth because of better contrast without ionizing radiation. The objectives were to develop MRI criteria for root crack/fracture identification and to establish reliability and accuracy in their detection.

METHODS

MRI-based criteria for crack/fracture appearance was developed by an MRI physicist and a panel of 6 dentists. Twenty-nine human adult teeth previously extracted after a clinical diagnosis of a root crack/fracture were frequency matched to 29 controls. Samples were scanned using an in vivo MRI protocol and the reference standard (ie, ex vivo limited field of view cone-beam computed tomographic [CBCT] imaging). A blinded, 4-member panel evaluated the images with a proportion randomly retested to establish intrarater reliability. Overall observer agreement, sensitivity, and specificity were computed for each imaging modality.

RESULTS

Subjectively, MRI has increased crack/fracture contrast and is less prone to artifacts from radiodense materials relative to CBCT imaging. Intrarater reliability for MRI was fair to excellent (κ = 0.38-1.00), and for CBCT imaging, it was moderate to excellent (κ = 0.66-1.00). Sensitivity for MRI was 0.59 (95% confidence interval [CI], 0.39-0.76; P = .46), and for CBCT imaging, it was 0.59 (95% CI, 0.59-0.76; P = .46). Specificity for MRI was 0.83 (95% CI, 0.64-0.94; P < .01), and for CBCT imaging, it was 0.90 (95% CI, 0.73-0.98; P < .01).

CONCLUSIONS

Despite advantages of increased contrast and the absence of artifacts from radiodense materials in MRI, comparable measures of sensitivity and specificity (to limited field of view CBCT imaging) suggest MRI quality improvements are needed, specifically in image acquisition and postprocessing parameters. Given the early stage of technology development, there may be a use for MRI in detecting cracks/fractures in teeth.

Accuracy of Different Imaging CBCT Systems for the Detection of Natural External Radicular Resorption Cavities: An Ex Vivo Study

OBJECTIVE

The aim of this study was to compare the sensitivity and specificity of 3 different systems of cone-beam computed tomography (CBCT) in the detection of natural external root resorption (ERR) cavities using microtomography as the gold standard.

METHOD

A sample of 126 ex vivo teeth were submitted to a microtomography examination to verify the presence/absence of ERR cavities. Then, they were divided into the control group: 85 teeth that did not present with an ERR cavity; and experimental group: 41 teeth that presented with 1 or more ERR cavities. The size of the natural ERR cavities varied from 2.46 mm³ to 3.11 mm³, which corresponded to cavities of 1.67 mm and 1.81 mm in diameter, respectively. The teeth were placed on a dry human mandible for scanning in each of the 3 protocols with different voxel sizes: 0.25 mm, 0.20 mm, and 0.166 mm.

RESULTS

The accuracy of the 3 protocols evaluated in this study are listed in decreasing order: 60.3% for a voxel size of 0.20 mm, 56.7% for a voxel size of 0.166 mm, and 46.7% for a voxel size of 0.25 mm; these are smaller values than previous studies have obtained using artificial ERR cavities. Statistically significant results were not found among the 3 CBCT protocols that were used (P > .05), and the receiver operating characteristic curve shows the small differences found between the protocols.

CONCLUSION

The results indicate that CBCT presents, for natural ERR, lower sensitivity and specificity values than those detected in previous studies of artificial cavities. The results demonstrate that natural ERR is neither easily observed nor accurately located by CBCT, as previous studies using artificial ERR indicated.

Accuracy of linear measurements on CBCT images related to presurgical implant treatment planning: A systematic review

OBJECTIVE

The aim of this systematic review was to identify, review, analyze, and summarize available evidence on the accuracy of linear measurements when using maxillofacial cone beam computed tomography (CBCT) specifically in the field of implant dentistry.

MATERIAL AND METHODS

The search was undertaken in April 2017 in the National Library of Medicine database (Medline) through its online site (PubMed), followed by searches in the Cochrane, EMBASE, ScienceDirect, and ProQuest Dissertation and Thesis databases. The main inclusion criterion for studies was that linear CBCT measurements were performed for quantitative assessment (e.g., height, width) of the alveolar bone at edentulous sites or measuring distances from anatomical structures related to implant dentistry. The studies should compare these values to clinical data (humans) or ex vivo and/or experimental (animal) findings from a "gold standard."

RESULTS

The initial search yielded 2,516 titles. In total, 22 studies were included in the final analysis. Of those, two were clinical and 20 ex vivo investigations. The major findings of the review indicate that CBCT provides cross-sectional images that demonstrate high accuracy and reliability for bony linear measurements on cross-sectional images related to implant treatment. A wide range of error has been reported when performing linear measurements on CBCT images, with both over- and underestimation of dimensions in comparison with a gold standard. A voxel size of 0.3 to 0.4 mm is adequate to provide CBCT images of acceptable diagnostic quality for implant treatment planning.

CONCLUSIONS

CBCT can be considered as an appropriate diagnostic tool for 3D preoperative planning. Nevertheless, a 2 mm safety margin to adjacent anatomic structures should be considered when using CBCT. In clinical practice, the measurement accuracy and reliability of linear measurements on CBCT images are most likely reduced through factors such as patient motion, metallic artefacts, device-specific exposure parameters, the software used, and manual vs. automated procedures.

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

AIM

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

METHODOLOGY

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

RESULTS

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

CONCLUSIONS

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

Determination of optimum exposure parameters for dentoalveolar structures of the jaws using the CB MercuRay system with cluster signal-to-noise analysis

OBJECTIVE

To determine the optimum cone beam computed tomography exposure parameters for specific diagnostic tasks.

METHODS

A Teflon phantom attached to a half-mandible in a large container was scanned in dental (D), implant (I), and panoramic (P) modes. An identical phantom in a small container was scanned in D mode. Both were scanned at 60, 80, 100, and 120 kV. We evaluated the image quality of five anatomical structures [dentinoenamel junction (1), lamina dura and periodontal ligament space (2), trabecular pattern (3), cortex-spongy bone junction (4), and pulp chamber and root canal (5)] and analyzed the diagnostic image quality with cluster signal-to-noise analysis. We then evaluated correlations between the two image qualities and calculated the threshold of acceptable diagnostic image quality. Optimum exposure parameters were determined from images with acceptable diagnostic image quality.

RESULTS

For the small container, the optimum exposure parameters were D mode, 80 kV for (1), (3), and (4) and D mode, 100 kV for (5). For the large container, they were D mode, 120 kV for (1), (3), and (5) and D mode, 100 kV for (4). I mode, 120 kV reached the acceptable level for (4). No images reached the acceptable level for (2).

CONCLUSIONS

No optimum exposure parameters were identified for the evaluation of the lamina dura and periodontal ligament space. D mode was sufficient for the other structures; however, the tube voltage required for each structure differed. Smaller patients required lower tube voltage. I mode, 120 kV may be used for larger lesions.

Comparison of cone-beam computed tomography with bitewing radiography for detection of periodontal bone loss and assessment of effects of different voxel resolutions: an in vitro study

OBJECTIVE

The aim of the study was to compare intraoral radiographs and CBCT images for detection of horizontal periodontal bone loss, and to investigate the diagnostic effect of different voxel resolutions in CBCT imaging.

METHODS

A total of 240 sites with horizontal bone loss were measured on the buccal, lingual, mesial, and distal surfaces of 60 posterior teeth in four maxillary and six mandibular bones obtained from cadavers (dry skulls). Direct measurements on the dry skulls were accepted as the gold standard values. Measurements on CBCT images at two different voxel resolutions (0.250 and 0.160 mm³) and intraoral bitewing radiographs were compared with one another and with the gold standard values.

RESULTS

The measurements on the CBCT images at two voxel resolutions and bitewing radiographs did not differ significantly (p > 0.05) from the direct measurements on the dry skulls. No significant difference was found between the bitewing radiographs and CBCT images for measurements in the mesial and distal regions (p > 0.05). There was no significant difference between the measurements on the buccal and lingual surfaces at the two different voxel resolutions (p > 0.05).

CONCLUSIONS

CBCT scans are recommended for evaluation of buccal and lingual bone loss to avoid intraoral radiographs that exceed routine examination of interproximal alveolar bone loss. Furthermore, instead of basing the voxel size on the required CBCT scans, it is recommended to select the smallest possible field of view to reduce the dose of radiation.

Imaging Factors Impacting on Accuracy and Radiation Dose in 3D Printing

Objectives

To compare reconstructed area and surface roughness of 3D models acquired using nine image acquisition protocols. Radiation dose was also compared among acquisition protocols.

Methods

A dry craniofacial specimen was scanned using three CT devices (a cone beam CT, a 16-channel fan beam CT, and a 64-channel fan beam CT), with three different acquisition protocols each. Nine 3D models were manufactured using polylactic acid. Surface roughness and reconstructed area were determined for each 3D model. The radiation dose during acquisitions was measured using lithium crystals. ANOVA was used to compare the data among the 3D models. Linear function optimization techniques based on stochastic variables were applied to identify the most suitable protocol for use.

Results

For surface roughness, statistically significant differences were observed among all 3D models and the specimen. For reconstructed area, CBCT and one CT-16 channel protocols originated 3D models statistically significant different from the specimen. Higher radiation doses were observed with fan beam CT acquisitions.

Conclusions

All three CT devices were suitable for 3D printing when used at full resolution. The highest reconstruct area vs. radiation dose ratio was found for 64-channel CT devices.

Morphofunctional evaluation of buccopharyngeal space using three-dimensional cone-beam computed tomography (3D-CBCT)

The present study aims to identify the anatomical functional changes of the buccopharyngeal space in case of singers with canto voice. The interest in this field is particularly important in view of the relation between the artistic performance level, phoniatry and functional anatomy, as the voice formation mechanism is not completely known yet. We conducted a morphometric study on three soprano voices that differ in type and training level. The anatomical soft structures from the superior vocal formant of each soprano were measured on images captured using the Cone-beam Computed Tomography (CBCT) technique. The results obtained, as well as the 3D reconstructions emphasize the particularities of the individual morphological features, especially in case of the experienced soprano soloist, which are found to be different for each anatomical soft structure, as well as for their integrity. The experimental results are encouraging and suggest further development of this study on soprano voices and also on other types of opera voices.

Accuracy of linear and volumetric measurements of artificial ERR cavities by using CBCT images obtained at 4 different voxel sizes and measured by using 4 different software: an ex vivo research

OBJECTIVES

To compare the accuracy of linear and volumetric measurements of artificial external root resorption (ERR) cavities by cone beam CT (CBCT) images obtained at four voxel sizes and by using four different software ex vivo.

METHODS

ERR cavities were created on 40 extracted single rooted anterior teeth. Images were obtained by using Planmeca CBCT unit at endo mode (0.075 mm); high-resolution mode (0.1 mm); high-definition mode (0.15 mm) and normal resolution mode (0.2 mm) voxel sizes. Images were analyzed by two observers using four different software (Romexis, 3D Doctor, ITK-SNAP, and OsiriX). (1) Diameter; (2) height; (3) depth; and (4) volume of the ERR were measured. CBCT measurements were then compared with direct physical measurements. ANOVA was used with general linear model analysis. The significance level was set at p < 0.05.

RESULTS

One-way ANOVA general linear model analysis showed no significant difference between or within observers for diameter, height, depth and volume measurements (p > 0.05). We found significant differences for diameter and volume measurements among softwares in terms of mean differences as compared to mean standard direct measurements (p < 0.05). We found statistically significant differences among voxel sizes and software for height measurements (p < 0.05). In addition, we found significant differences for diameter and volume measurements (p < 0.05) suggesting more accurate measurements for the cervical region when compared to apical region.

CONCLUSIONS

Observers using CBCT images obtained at four voxel sizes performed similarly in the quantification of artificial ERR with clinically insignificant distinction between CBCT softwares used.

Evaluation of root resorption after comprehensive orthodontic treatment using cone beam computed tomography (CBCT): a meta-analysis

Background

Orthodontic treatment can result in root resorption (RR). Traditional two-dimensional (2D) data exhibit magnification, deformation and positioning problems. Cone beam computed tomography (CBCT) contains more accurate three-dimensional (3D) information. This study identified and qualified the extent and location of root resorption using cone beam computed tomography (CBCT) after comprehensive orthodontic treatment.

Methods

Studies comparing the RR before and after comprehensive orthodontic treatment using CBCT were identified using electronic searches of databases, including Cochrane, PubMed, EMBASE, China National Knowledge Infrastructure (CNKI) and Web of Science, and manual searches in relevant journals and the reference lists of the included studies until Oct 25, 2017. The extraction of data and the risk of bias evaluation were conducted by two investigators independently. The methodological quality of the included studies was assessed using the methodological index for non-randomized studies (MINORS). Studies that reported the length and volume of teeth were used for quantitative analyses.

Results

Twelve studies were included in the meta-analysis. The length of all teeth after intervention was significantly shorter than that before treatment (MD = 0.80, 95% CI 0.56, 1.03, P < 0.00001). The sequence of RR from heaviest to lightest was maxillary lateral incisors, maxillary central incisors, mandibular anterior teeth, and maxillary canines. Studies were divided into two subgroups based on the use of tooth extraction. Root shortening after treatment was observed in both groups, and extraction caused more root resorption than was observed in the non-extraction group.

Conclusions

There were different degrees of root resorption after orthodontics, but it was clinically acceptable. Root resorption established in CBCT research was less serious and more accurate than that observed in the two-dimensional research. Current evidence suggests that root length and volume were reduced after orthodontic treatment. The order of the amount of RR was maxillary lateral incisors, maxillary central incisors and mandibular anterior teeth. Most of the articles were complicated by different confounding factors. Therefore, more high-quality clinical trials are needed to determine the risk factors of root resorption and optimal protocols for treatment and to draw more reliable conclusions.

CBCT assessment of radicular volume loss after rapid maxillary expansion: A systematic review

Background

The present systematic review analyzed the current literature to investigate whether rapid maxillary expansion (RME) causes radicular resorption, assessed by cone-beam computed tomography (CBCT).

Material and Methods

Eighteen electronic databases and reference lists of studies were searched up to November 2017. Grey literature was also screened. To be included, articles must be human studies on growing subjects with transversal maxillary deficiency treated with maxillary expansion protocol and with 3-D radiographic assessment of radicular volume by CBCT images. Two authors independently performed study selection, data extraction, and risk of bias assessment. Study characteristics (study design, sample size, age, sex, skeletal maturity, type of appliance, daily activation, teeth evaluated, CBCT settings), and study outcomes (radicular volume loss) were reported according to the PRISMA statement.

Results

Only 3 articles were considered eligible and an individual analysis of the selected articles was undertaken. The risk of bias assessment revealed low methodological quality for all the studies included. In all the considered studies, significant radicular volume loss was observed in posterior teeth, following RME. When reported in percentage, the radicular volumetric loss was similar between anchored (first molars and first premolars) and unanchored teeth (second premolars).

Conclusions

A preliminary evaluation of the patient-related risk factors for RR is warmly advisable when administering RME.

Key words:RME, maxillary expansion, root resorption, external root resorption.

Diagnostic accuracy of cone-beam computed tomography scans with high- and low-resolution modes for the detection of root perforations

Purpose

This study compared the diagnostic accuracy of cone-beam computed tomography (CBCT) scans obtained with 2 CBCT systems with high- and low-resolution modes for the detection of root perforations in endodontically treated mandibular molars.

Materials and Methods

The root canals of 72 mandibular molars were cleaned and shaped. Perforations measuring 0.2, 0.3, and 0.4 mm in diameter were created at the furcation area of 48 roots, simulating strip perforations, or on the external surfaces of 48 roots, simulating root perforations. Forty-eight roots remained intact (control group). The roots were filled using gutta-percha (Gapadent, Tianjin, China) and AH26 sealer (Dentsply Maillefer, Ballaigues, Switzerland). The CBCT scans were obtained using the NewTom 3G (QR srl, Verona, Italy) and Cranex 3D (Soredex, Helsinki, Finland) CBCT systems in high- and low-resolution modes, and were evaluated by 2 observers. The chi-square test was used to assess the nominal variables.

Results

In strip perforations, the accuracies of low- and high-resolution modes were 75% and 83% for NewTom 3G and 67% and 69% for Cranex 3D. In root perforations, the accuracies of low- and high-resolution modes were 79% and 83% for NewTom 3G and was 56% and 73% for Cranex 3D.

Conclusion

The accuracy of the 2 CBCT systems was different for the detection of strip and root perforations. The Cranex 3D had non-significantly higher accuracy than the NewTom 3G. In both scanners, the high-resolution mode yielded significantly higher accuracy than the low-resolution mode. The diagnostic accuracy of CBCT scans was not affected by the perforation diameter.

Reliability and accuracy of linear measurements in cone-beam computed tomography using different software programs and voxel sizes

Objectives:

The aim of this study is to evaluate the accuracy of linear measurements on cone-beam computed tomography (CBCT) images using three software programs and different voxel sizes.

Methods:

Ten human mandibles with 25 silica markers were scanned for 0.250-, 0.300-, and 0.400-mm voxels in the i-CAT New Generation (Imaging Sciences International, Hatfield, PA, USA). Thirty-five linear measurements were carried out by two examiners two times on the multiplanar reconstructions in the following software programs: XoranCat version 3.1.62 (Xoran Technologies, Ann Arbor, MI, USA), RadiAnt DICOM 2.2.9 Viewer (Medixant, Poznan- Poland) and InVesalius 3.0.0 (Centro de Tecnologia da Informação Renato Archer, Campinas, SP, Brazil). The physical measurements were made by another observer two times using a digital caliper on the macerated mandibles. ANOVA test was used to compare voxels and software programs. Pearson correlation and the Bland–atman tests were used to compare physical and virtual measurements and to evaluate the accuracy of the software programs, respectively (P < 0.05).

Results:

There was no statistically significant difference when the measurements were compared in acquisitions with different voxel sizes analyzed in the three software programs. There was also no difference when the measurements were compared between the software programs and the digital caliper. Excellent intra- and inter-observer reliability for the markers, physical measurements, and multiplanar reconstructions were found.

Conclusion:

Linear measurements in the XoranCat, Radiant, and InVesalius software programs are reliable and accurate compared with physical measurements. The different acquisition protocols using different voxel sizes did not influence the accuracy of linear measurements in CBCT images.

Impact of cone-beam computed tomography scan mode on the diagnostic yield of chemically simulated external root resorption

INTRODUCTION

The aim of this in-vitro study was to evaluate the influence of cone-beam computed tomography scans on the diagnosis of chemically simulated external root resorption.

METHODS

One hundred extracted anterior teeth were selected. Subsurface demineralization was induced on a limited area of the apical third of the root of 49 teeth. Each tooth was placed in an empty socket of a partially edentulous dry mandible. Cone-beam computed tomography images were obtained according to 3 protocols: (1) half scan, 0.40-mm voxel size; (2) full scan, 0.40-mm voxel size; and (3) full scan, 0.125-mm voxel size. Three observers evaluated the images. Sensitivity, specificity, accuracy, and area under the curve were compared with the Cochran Q and Mann-Whitney U tests.

RESULTS

Protocol 3 had the highest sensitivity (81.63%), accuracy (80.67%), and area under the curve (0.807). There were statistically significant differences between protocol 3 and the other 2 protocols (P <0.001). The specificity of protocol 1 (84.97%) was greater than that of protocols 2 (69.93%) and 3 (79.74%); however, a statistically significant difference was found only between protocols 1 and 2 (P = 0.005).

CONCLUSIONS

A more dedicated, high-resolution scan should be acquired when one intends to investigate the early stage of external root resorption during orthodontic treatment. However, this does not imply that all orthodontic patients should be subjected to high-dose cone-beam computed tomography scans.

Accuracy Assessment of Three-dimensional Surface Reconstructions of In vivo Teeth from Cone-beam Computed Tomography

Background:

The accuracy of three-dimensional (3D) reconstructions from cone-beam computed tomography (CBCT) has been particularly important in dentistry, which will affect the effectiveness of diagnosis, treatment plan, and outcome in clinical practice. The aims of this study were to assess the linear, volumetric, and geometric accuracy of 3D reconstructions from CBCT and to investigate the influence of voxel size and CBCT system on the reconstructions results.

Methods:

Fifty teeth from 18 orthodontic patients were assigned to three groups as NewTom VG 0.15 mm group (NewTom VG; voxel size: 0.15 mm; n = 17), NewTom VG 0.30 mm group (NewTom VG; voxel size: 0.30 mm; n = 16), and VATECH DCTPRO 0.30 mm group (VATECH DCTPRO; voxel size: 0.30 mm; n = 17). The 3D reconstruction models of the teeth were segmented from CBCT data manually using Mimics 18.0 (Materialise Dental, Leuven, Belgium), and the extracted teeth were scanned by 3Shape optical scanner (3Shape A/S, Denmark). Linear and volumetric deviations were separately assessed by comparing the length and volume of the 3D reconstruction model with physical measurement by paired t-test. Geometric deviations were assessed by the root mean square value of the imposed 3D reconstruction and optical models by one-sample t-test. To assess the influence of voxel size and CBCT system on 3D reconstruction, analysis of variance (ANOVA) was used (α = 0.05).

Results:

The linear, volumetric, and geometric deviations were −0.03 ± 0.48 mm, −5.4 ± 2.8%, and 0.117 ± 0.018 mm for NewTom VG 0.15 mm group; −0.45 ± 0.42 mm, −4.5 ± 3.4%, and 0.116 ± 0.014 mm for NewTom VG 0.30 mm group; and −0.93 ± 0.40 mm, −4.8 ± 5.1%, and 0.194 ± 0.117 mm for VATECH DCTPRO 0.30 mm group, respectively. There were statistically significant differences between groups in terms of linear measurement (P < 0.001), but no significant difference in terms of volumetric measurement (P = 0.774). No statistically significant difference were found on geometric measurement between NewTom VG 0.15 mm and NewTom VG 0.30 mm groups (P = 0.999) while a significant difference was found between VATECH DCTPRO 0.30 mm and NewTom VG 0.30 mm groups (P = 0.006).

Conclusions:

The 3D reconstruction from CBCT data can achieve a high linear, volumetric, and geometric accuracy. Increasing voxel resolution from 0.30 to 0.15 mm does not result in increased accuracy of 3D tooth reconstruction while different systems can affect the accuracy.

Efficacy of Different Cone-beam Computed Tomographic Protocols in the Identification of Mesiobuccal Canals of Maxillary First Molars: A Tomographic and Ex Vivo Study

INTRODUCTION

Complementary methods of anatomic diagnosis, including cone-beam computed tomographic (CBCT) imaging, may be useful in the diagnosis of mesiobuccal (MB) canals of maxillary molars.

METHODS

Thirty-five maxillary first molars were subjected to ex vivo analysis and 4 CBCT protocols: i-CAT Classic (Imaging Sciences International, Hatfield, PA) (ICC group), i-CAT Next Generation (Imaging Sciences International) (ICN group), PreXion 3D (PreXion, San Mateo, CA) (16.8-second acquisition time; PX1 group), and PreXion 3D (33.5-second acquisition time; PX2 group). The images were evaluated by 2 calibrated endodontists who kept records following protocols previously published in the literature. Micro-computed tomographic imaging was used as the control.

RESULTS

The correct identification of anatomic variations of MB roots was 54.3% (n = 19) in the ICC group, 65.7% (n = 23) in the ICN group, and 80.0% (n = 28) in the PX1 and PX2 groups. The probability of agreement between the ICC and the control groups was significantly different from the probability of agreement with the PX1 (P < .05) and PX2 (P < .05) groups. The other groups showed no significant differences compared with the control group. There was no difference in the probability of agreement between the tomographic protocols and the ex vivo results.

CONCLUSIONS

The PX1 and PX2 groups were more effective for the diagnosis of MB canals. PX1 is the most suitable because it results in a shorter radiation time and diagnostic imaging similar to PX2. The single-canal anatomy was the most prevalent in the study.

Cone-beam computed tomography versus periapical radiograph for diagnosing external root resorption: A systematic review and meta-analysis

OBJECTIVE

To compare the diagnostic accuracy of cone-beam computed tomography (CBCT) and periapical radiographs (PR) for the detection of external root resorption (ERR).

MATERIAL AND METHODS

An electronic search in databases, including the Cochrane Central Register of Controlled Trials, PubMed, Embase, the China National Knowledge Infrastructure, and System for Information on Grey Literature in Europe (SIGLE), was performed until August 2016. A manual search of relevant journals and reference lists of enrolled studies was conducted. The studies investigating the diagnostic accuracy of CBCT or PR for ERR, with simulated ERR as the reference test, were considered eligible. The diagnostic accuracy of CBCT and PR was statistically pooled using a bivariate model. Meta-regression and subgroup analysis were performed to explore the sources of heterogeneity. Sensitivity analysis was used to test the stability of the overall results in the meta-analysis.

RESULTS

A total of 15 studies were included in this systematic review. The pooled results showed that CBCT had significantly higher sensitivity (0.89; 95% confidence interval [CI]: 0.77-0.96) and area under curve (0.96; 95% CI: 0.77-0.96) than PR (sensitivity: 0.68; 95% CI: 0.56-0.78; area under curve: 0.88; 95% CI: 0.85-0.90). No difference in sensitivity, specificity, and area under the curve between conventional and digital PR was observed.

CONCLUSIONS

Currently available evidence suggests that CBCT could be reliable to detect the presence of ERR in clinical practice and has a higher diagnostic efficacy than PR.

Detection of Second Mesiobuccal Canals in Maxillary First Molars Using a New Angle of Cone Beam Computed Tomography

Background

The localization of the additional canal orifice is one of the primary factors influencing the success of endodontic treatment. To deal with this problem, several techniques that each have their own advantages and disadvantages have been discussed in the literature.

Objectives

The aim of the present in vitro study was to review a new approach to localizing second mesiobuccal (MB2) canals in maxillary first molars using cone beam computed tomography (CBCT).

Patients and Methods

The CBCT scans of 296 patients who were referred to the department of dentomaxillofacial radiology were included in the study. The presence of MB2 canals, the angle formed by the mesiobuccal, distobuccal, and palatal root canal orifices (∠MDP), and the angle formed by the mesiobuccal, distobuccal, and MB2 canal orifices (∠MDMB2) were evaluated on the axial section. Pearson correlation and multiple linear regression methods were used for all predictions. All of the analyses were performed using SPSS for windows version 22.0. A two-sided P value < 0.05 was defined as statistically significant.

Results

Of the 468 first molars, MB2 canals were observed in 296 subjects (141 females and 155 males). There were no statistically significant differences between females and males (P = 0.300). The ∠MDP and ∠MDMB2 were detected and evaluated. A moderate positive correlation was found between the ∠MDP and the ∠MDMB2. To predict the ∠MDMB2 values, it was shown that the ∠MDMB2 increased by 0.420 degrees when the ∠MDP increased by 1 degree. If the ∠MDP was greater than 90.95 degrees, there was a 78% probability that MB2 canals could be found.

Conclusion

The determination of the presence of MB2 in the maxillary first molars may be carried out using CBCT scans. If the ∠MDP was 91 degrees or greater, there was considered to be a higher probability that MB2 canals would be found in the endodontic cavity. Due to the positive correlation between the ∠MDP and the ∠MDMB2, the localization of MB2 canals may be easily performed in relation to the main MB canal.

Accuracy in the diagnosis of vertical root fractures, external root resorptions, and root perforations using cone-beam computed tomography with different voxel sizes of acquisition

AIM

The aim of this study is to assess the accuracy of images acquired with cone-beam computed tomography (CBCT) in the identification of three different root alterations.

MATERIALS AND METHODS

Forty human premolars were allocated to four experimental groups (n = 10): sound teeth (control), vertical root fracture (VRF), external root resorption (ERR), and root perforation (RP). After the root alterations had been produced, four teeth were randomly assembled into 10 macerated mandibles and submitted to CBCT. Images were acquired with five voxel sizes (0.125, 0.200, 0.250, 0.300, and 0.400 mm) and assessed by three experienced dental radiologists. Sensitivity, specificity, positive and negative predictive values, and the areas under the receiver operating characteristic curve (accuracy) were calculated. The accuracy of imaging in different voxel sizes was compared with Tukey exact binomial test (α=5%).

RESULTS

Accuracy with voxel sizes 0.125, 0.200, and 0.250 mm was significantly higher in the detection of ERRs and VRFs than voxel sizes 0.300 and 0.400 mm. No statistical difference was found in terms of accuracy among any of the studied voxel sizes in the identification of RPs.

CONCLUSIONS

Voxel size 0.125 mm produced images with the best resolution without increasing radiation levels to the patient when compared to voxel sizes 0.200 and 0.250 mm. Voxel sizes 0.300 and 0.400 mm should be avoided in the identification of root alterations.