Comparison of panoramic radiograph and cone beam computed tomography findings for impacted mandibular third molar root and inferior alveolar nerve canal relation

Objectives

This study was aimed at determining the specific signs of close relationship between impacted mandibular third molar (IMTM) root and inferior alveolar nerve (IAN) canal as visualised on digital panoramic radiograph or orthopantomograph (OPG) which should indicate as well as contraindicate the need for cone beam computed tomography (CBCT) imaging based on hierarchical model of Fryback and Thornbury.

Materials and Methods

The sample consisted of 120 individuals (200 IMTM) who had undergone OPG as well as CBCT imaging as preoperative radiographic evaluation before surgical extraction. On panoramic radiographs; Rood and Sheehab's radiographic signs of IMTM root and IAN canal, impacted third molar position based on Winter's classification and depth of impaction based on Pell and Gregory's classification were evaluated. On CBCT; presence/absence of corticalization and the status of the buccal and lingual cortices (thinning/perforation) were evaluated. These findings of OPG were compared to CBCT findings to determine the better modality based on hierarchical model of Fryback and Thornbury.

Results

Statistically significant association was found between radiographic signs of Rood and Sheehab such as 'no relation' and 'superimposition' on OPG and presence of corticalization between IMTM root and IAN canal on CBCT. Statistically significant association was also found between 'mesioangular' and 'vertical' positions of Winter's classification as well as 'class 1A' of Pell and Gregory's classification of IMTM on OPG and presence of corticalization on CBCT. CBCT was found to be having lesser variance and greater F value as compared to OPG for evaluation of IMTM.

Conclusions

On OPG; Rood and Sheehab's radiographic signs such as 'no relation' and 'superimposition', Winter's 'mesioangular' and 'vertical' and Pell and Gregory's 'Class 1A' are not indicative for CBCT examination before surgical extraction is attempted. On OPG; Rood and Sheehab's radiographic signs such as interruption of white line, darkening of root, darkening of canal, deflection of root, narrowing of canal as well as diversion of canal are all frequently associated with absence of corticalization between IMTM root and IAN canal and hence require CBCT examination before surgical extraction is attempted so that post-operative neurological complications can be minimised. Also, Winter's horizontal, distoangular and others as well Pell and Gregory's classes 1B,1C,2A,2B,2C,3A,3B,3C are indicative for CBCT examination before surgical extraction is attempted. Fryback and Thornbury model-based comparison proves that CBCT is a better radiographic modality as compared to OPG for evaluation of IMTM relation with IAN canal.

Long term skeletal and dental changes between tooth-anchored versus Dresden bone-anchored rapid maxillary expansion using CBCT images in adolescents: Randomized clinical trial

OBJECTIVE

The aim of this study was to determine long-term skeletal and dental changes in tooth-anchored versus Dresden bone-anchored rapid maxillary expansion using CBCT images in adolescents.

MATERIALS AND METHODS

In all, 29 adolescent patients (11-17 years of age) needing skeletal expansion were randomly allocated to two different groups treated by either a Dresden bone-anchored expander or a conventional hyrax expander. Patients included did not have previous orthodontic treatment, were non-syndromic and had all teeth present in mouth. CBCT images were taken before expansion and two or more years after expansion. An independent T-test was used to determine the statistical significance between treatment groups and paired T-test was used to compare the results before and after expansion in each group.

RESULTS

Neither treatment group showed overall long-term different skeletal and dental changes in the transverse, anterior-posterior and vertical planes (P<0.05). Both treatment groups showed mild asymmetric skeletal expansion, but these were clinically insignificant.

CONCLUSIONS

Both expanders had similar skeletal and dental results. The greatest changes were in the transverse plane. Changes in vertical and anterior-posterior were negligible.

Cone beamed computed tomography in pediatric dentistry: Concepts revisited

Oral diagnosis and treatment planning is of utmost importance in pediatric dentistry. Although intraoral and conventional radiographic procedures have been used extensively since decades, there two-dimensional representation has raised many questions. Cone beamed computed tomography with 3-D technology is a replacement for conventional 2-D imaging and has a wide application among child patients in pediatric dentistry. This article therefore deals with current facts and myths about clinical situations where CBCT is indicated in pediatric patients.

Pose-aware instance segmentation framework from cone beam CT images for tooth segmentation

Individual tooth segmentation from cone beam computed tomography (CBCT) images is an essential prerequisite for an anatomical understanding of orthodontic structures in several applications, such as tooth reformation planning and implant guide simulations. However, the presence of severe metal artifacts in CBCT images hinders the accurate segmentation of each individual tooth. In this study, we propose a neural network for pixel-wise labeling to exploit an instance segmentation framework that is robust to metal artifacts. Our method comprises of three steps: 1) image cropping and realignment by pose regressions, 2) metal-robust individual tooth detection, and 3) segmentation. We first extract the alignment information of the patient by pose regression neural networks to attain a volume-of-interest (VOI) region and realign the input image, which reduces the inter-overlapping area between tooth bounding boxes. Then, individual tooth regions are localized within a VOI realigned image using a convolutional detector. We improved the accuracy of the detector by employing non-maximum suppression and multiclass classification metrics in the region proposal network. Finally, we apply a convolutional neural network (CNN) to perform individual tooth segmentation by converting the pixel-wise labeling task to a distance regression task. Metal-intensive image augmentation is also employed for a robust segmentation of metal artifacts. The result shows that our proposed method outperforms other state-of-the-art methods, especially for teeth with metal artifacts. Our method demonstrated 5.68% and 30.30% better accuracy in the F1 score and aggregated Jaccard index, respectively, when compared to the best performing state-of-the-art algorithms. The major implication of the proposed method is two-fold: 1) an introduction of pose-aware VOI realignment followed by a robust tooth detection and 2) a metal-robust CNN framework for accurate tooth segmentation.

Influence of tongue volume, oral cavity volume and their ratio on upper airway: A cone beam computed tomography study

Background

Our study aimed to measure the tongue volume (TV), oral cavity volume (OCV), and their ratio (TV/OCV) and correlate with upper airway using cone-beam computed tomography (CBCT).

Method

The volume of oral cavity, tongue and upper airway were obtained by the manual process of segmentation of CBCT data of 15 subjects. The mean age of the sample was 21.86 years (range 15-33 years). Segmentation of the upper airway, tongue and oral cavity was performed manually using Mimics 11.0 (Materialise, Leuven, Belgium) software at different thresholds for air and the tongue. The Hounsfield units (HU) for airway volume of the different facial region ranged from -1024 to -500. For tongue volume, Hounsfield units (HU), ranging from -200 to 200 was calculated.

Results

A significant negative correlation between TV/OCV and oropharynx (r = - 0.51; P = 0.04), TV/OCV and oral cavity airway volume (r = - 0.74; P = 0.002) was found. There was a significant and a positive correlation with TV/OCV and tongue volume (r = 0.65; P = 0.009).

Conclusion

A significant negative correlation established between TV/OCV, oropharynx and oral cavity airway volume. This finding indicates an influence tongue volume, oral cavity volume and their ratio on patency of the oropharynx.

Adaptive radiotherapy and the dosimetric impact of inter- and intrafractional motion on the planning target volume for prostate cancer patients

Purpose

To investigate the dosimetric influence of daily interfractional (inter) setup errors and intrafractional (intra) target motion on the planning target volume (PTV) and the possibility of an offline adaptive radiotherapy (ART) method to correct larger patient positioning uncertainties in image-guided radiotherapy for prostate cancer (PCa).

Materials and methods

A CTV (clinical target volume)-to-PTV margin ranging from 15 mm in LR (left-right) and SI (superior-inferior) and 5–10 mm in AP (anterior-posterior) direction was applied to all patients. The dosimetric influence of this margin was retrospectively calculated by analysing systematic and random components of inter and intra errors of 31 consecutive intermediate- and high-risk localized PCa patients using daily cone beam computed tomography and kV/kV (kilo-Voltage) imaging. For each patient inter variation was assessed by observing the first 4 treatment days, which led to an offline ART-based treatment plan in case of larger variations.

Results:

Systematic inter uncertainties were larger (1.12 in LR, 2.28 in SI and 1.48 mm in AP) than intra systematic errors (0.44 in LR, 0.69 in SI and 0.80 mm in AP). Same findings for the random error in SI direction with 3.19 (inter) and 2.30 mm (intra), whereas in LR and AP results were alike with 1.89 (inter) and 1.91 mm (intra) and 2.10 (inter) and 2.27 mm (intra), respectively. The calculated margin revealed dimensions of 4–5 mm in LR, 8–9 mm in SI and 6–7 mm in AP direction. Treatment plans which had to be adapted showed smaller variations with 1.12 (LR) and 1.72 mm (SI) for Σ and 4.17 (LR) and 3.75 mm (SI) for σ compared to initial plans with 1.77 and 2.62 mm for Σ and 4.46 and 5.39 mm for σ in LR and SI, respectively.

Conclusion

The currently clinically used margin of 15 mm in LR and SI and 5–10 mm in AP direction includes inter and intra uncertainties. The results show that offline ART is feasible which becomes a necessity with further reductions in PTV margins.

Electronic supplementary material

The online version of this article (10.1007/s00066-020-01596-x) contains supplementary material, which is available to authorized users.

Correlation between facial growth patterns and cortical bone thickness assessed with cone-beam computed tomography in young adult untreated patients

Background

The vertical facial growth pattern is one of the most important issue in the orthodontic diagnosis and treatment. Previous studies investigated the association between interdental bone thickness and facial divergence using mainly bidimensional analysis. When two-dimensional dental radiographic views are not sufficient for diagnosis and measurements, cone-beam computed tomography (CBCT) images should be used to assess the alveolar bone structure three-dimensionally and with high accuracy and reliability.

The aim of the present study was to evaluate the correlation between alveolar bone thickness and facial divergence in young adults untreated patients using a three-dimensional method analysis with CBCT images.

Methods

Records of 30 untreated patients (mean age 16 ± 2 years) with Angle Class I and mild to moderate crowding were analyzed. Subjects were classified as hypodivergent (<39˚), normodivergent (41 ± 2˚), and hyperdivergent (>43°). according to the inter-maxillary angle between the sagittal maxillary plane (ANS-PNS) and the mandibular plane (GN-ME). The alveolar bone thickness measurements were taken for the buccal and palatal/lingual surfaces of maxillary and mandibular anterior teeth. Axial-guided navigation (AGN) was used to locate all landmarks using a specific software (Horos 3.0).

Results

The statistical analysis showed a significant difference between the hypodivergent and hyperdivergent group regarding buccal bone height (P = 0.005), buccal apical bone thickness (P = 0.003) and palatal mid-root bone thickness (P = 0.006). Moreover, buccal bone height (P = 0.006) was found to be statistically significant different in normodivergent compared with hypodivergent individuals.

Conclusions

Facial types were found to be correlated with alveolar bone thickness. The hyperdivergent subjects presented thinner alveolus bone in the anterior maxilla and at almost all sites in the mandible. Clinicians should be aware of the possibility of thin cortical bone plates in hyperdivergent patients, reducing antero-posterior movements to avoid fenestration and dehiscence.

Measurement error and reliability of three available 3D superimposition methods in growing patients

Introduction

Cone-Beam Computed Tomography (CBCT) images can be superimposed, allowing three-dimensional (3D) evaluation of craniofacial growth/treatment effects. Limitations of 3D superimposition techniques are related to imaging quality, software/hardware performance, reference areas chosen, and landmark points/volumes identification errors. The aims of this research are to determine/compare the intra-rater reliability generated by three 3D superimposition methods using CBCT images, and compare the changes observed in treated cases by these methods.

Methods

Thirty-six growing individuals (11–14 years old) were selected from patients that received orthodontic treatment. Before and after treatment (average 24 months apart) CBCTs were analyzed using three superimposition methods. The superimposed scans with the two voxel-based methods were used to construct surface models and quantify differences using SlicerCMF software, while distances in the landmark-derived method were calculated using Excel. 3D linear measurements of the models superimposed with each method were then compared.

Results

Repeated measurements with each method separately presented good to excellent intraclass correlation coefficient (ICC ≥ 0.825). ICC values were the lowest when comparing the landmark-based method and both voxel-based methods. Moderate to excellent agreement was observed when comparing the voxel-based methods against each other. The landmark-based method generated the highest measurement error.

Conclusions

Findings indicate good to excellent intra-examiner reliability of the three 3D superimposition methods when assessed individually. However, when assessing reliability among the three methods, ICC demonstrated less powerful agreement. The measurements with two of the three methods (CMFreg/Slicer and Dolphin) showed similar mean differences; however, the accuracy of the results could not be determined.

Three-dimensional position of mandibular third molars and its association with distal caries in mandibular second molars: a cone beam computed tomographic study

OBJECTIVE

To analyze the prevalence of distal caries in mandibular second molars (M2Ms) and its correlation with the three-dimensional position of mandibular third molars (M3Ms) by cone beam computed tomography (CBCT) images.

MATERIALS AND METHODS

CBCT scans involving 421 M3Ms were assessed. The presence of distal caries of M2Ms, patient age and gender, impaction depths and mesial angulation of M3Ms, the cementoenamel junction (CEJ) distances and contact point localization, and the horizontal positions of M3Ms were assessed. Risk factors were identified by multivariate logistic regression analysis.

RESULTS

The overall prevalence of distal caries in M2Ms was 31.6%. Mesial angulation (16°-75°) of M3Ms, contact point localization at or below the CEJ of M2Ms, and a buccal or lingual position of M3Ms relative to the molar line were identified as risk factors for the prevalence of distal caries in M2Ms (p < 0.05). Distal caries was more severe when the mesial angulation of M3Ms was 16°-75° (p < 0.05).

CONCLUSIONS

Buccal or lingual position of M3Ms may represent a new risk factor for the distal caries in M2Ms. Mesial angulation (16°-75°) of M3Ms is a predictive parameter for both the presence and severity of distal caries in M2Ms.

CLINICAL RELEVANCE

As the presence of distal caries in M2Ms is significantly associated with the three-dimensional position of M3Ms, watchful monitoring or prophylactic removal of M3Ms should be deliberated when M3Ms are mesially angulated (16°-75°), buccally or lingually positioned, and with the contact point localization at or below the CEJ of M2Ms.

Comparison of bone thickness in infrazygomatic crest area at various miniscrew insertion angles in Dravidian population - A cone beam computed tomography study

INTRODUCTION

Infrazygomatic crest miniscrews are an important advancement in the field of orthodontics for anchorage reinforcement. The size of the miniscrews and the site of placement depend on the bone thickness in the infazygomatic crest area. The bone morphology and the thickness vary among different ethnicities of population.

OBJECTIVES

To assess the bone thickness in the infrazygomatic crest area around the distobuccal root of the maxillary first molar using cone beam computed tomography and determine the best possible site and angulation for the placement of the miniscrew. Therefore, to determine the size of the implant that will suit the Dravidian population.

METHODS

The infrazygomatic crest bone thickness was evaluated on 10 patients using cone beam computed tomography. The measurements were made along the distobuccal root of maxillary first molar at different angulations ranging from 75° to 40° to the occlusal surface of the molar.

RESULTS

The infrazygomatic crest bone thickness was of 4.5mm to 9mm for the Dravidian population, when measured at an angle of 40° to 75° to the maxillary first molar occlusal plane and of 11 to 17mm above the occlusal plane. Student t-test (confidence interval 95%) was done to determine gender variation and compare the bone thickness of right and left side. ANOVA and post-hoc test were done to find the statistical difference between the bone thickness measured at different insertion angles.

CONCLUSIONS

The best possible site for miniscrew insertion is 12 to 17mm above the occlusal plane at an angle of 65° to 70°, with no injury to the adjacent anatomical structures, no mucosal irritation and adequate stability for the miniscrew. The ideal infrazygomatic crest screw length for Dravidian population is 9 to 11mm.

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 Panoramic Radiography for Degenerative Changes of the Temporomandibular Joint

Background:

Temporomandibular joint (TMJ) morphologies are complex, and changes in joint components have been studied extensively. TMJ conditions have many different etiologies, appearances, and relevant clinical significance.

Objective:

The objective of this study was to evaluate the concordance of the diagnosis of degenerative changes in the TMJ in panoramic radiographs.

Materials and Methods:

Cone beam computed tomography (CBCT) was used as a reference standard. Images of 84 patients (168 TMJs), 61 females (72.6%) and 23 males (27.4%) with an average age of 47.4 years, were evaluated by three radiologists who established the presence or absence of degenerative changes in the jaw heads. The data were collected and organized in a spreadsheet. Concordance between evaluators was analyzed using agreement percentages, statistical κ, and confidence intervals. In the analysis of compliance with CBCT, sensitivity, specificity, predictive positive and negative values, and probabilities of false positives and negatives were also calculated. All inferential tests were performed with a 5% significance level.

Results:

The percentage of agreement among raters in panoramic radiographs ranged from 66.7% to 82.9%, considered mild to moderate. Correlation between radiographic and tomographic images ranged from 45.5% to 64.9% in the inter-evaluator reviews, representing a very mild agreement. Sensitivity ranged from 28.6% to 58.7% and specificity from 66.7% to 100.0%. Positive predictive value ranged from 77.1% to 100.0%; the negative predictive value was lower, ranging from 32.2% to 54.8%. The probability of false negatives was higher than that of false positives, ranging from 45.2% to 67.8%.

Conclusion:

The rater did not reach acceptable diagnosis levels.

Bone regeneration and graft material resorption in extraction sockets grafted with bioactive silica-calcium phosphate composite (SCPC) versus non-grafted sockets: clinical, radiographic, and histological findings

Purpose

The purpose of the present study was to evaluate the effect of silica-calcium phosphate composite (SCPC) granules on bone regeneration in extraction sockets.

Methods

Ten patients were selected for a split-model study. In each patient, bone healing in SCPC-grafted and control ungrafted sockets was analyzed through clinical, radiographic, histomorphometric, and immunohistochemical assessments 6 months postoperatively.

Results

A radiographic assessment using cone-beam computed tomography showed minimal ridge dimension changes in SCPC-grafted sockets, with 0.39 mm and 1.79 mm decreases in height and width, respectively. Core bone biopsy samples were obtained 6 months post-extraction during implant placement and analyzed. The average percent areas occupied by mature bone, woven bone, and remnant particles in the SCPC-grafted sockets were 41.3%±12%, 20.1%±9.5%, and 5.3%±4.4%, respectively. The percent areas of mature bone and woven bone formed in the control ungrafted sockets at the same time point were 31%±14% and 24.1%±9.4%, respectively. Histochemical and immunohistochemical analyses showed dense mineralized bundles of type I collagen with high osteopontin expression intensity in the grafted sockets. The newly formed bone was well vascularized, with numerous active osteoblasts, Haversian systems, and osteocytes indicating maturation. In contrast, the new bone in the control ungrafted sockets was immature, rich in type III collagen, and had a low osteocyte density.

Conclusions

The resorption of SCPC granules in 6 months was coordinated with better new bone formation than was observed in untreated sockets. SCPC is a resorbable bone graft material that enhances bone formation and maturation through its stimulatory effect on bone cell function.

Trial Registration

ClinicalTrials.gov Identifier: NCT03897010

Comparative evaluation of image registration methods with different interest regions in lung cancer radiotherapy

BACKGROUND

Lung cancer is a leading cause of morbidity and mortality worldwide. Radiotherapy for lung cancer is beneficial in both the radical and palliative settings, and technologic advances in recent years now afford an opportunity for this treatment to be more targeted than ever before. Although the delivery of more accurate forms of radiotherapy has minimized the risks of side-effects, how to utilize this treatment to optimize outcomes remains questionable. This study aimed to evaluate the accuracy of cone beam computed tomography (CBCT) image registration used in image-guided radiotherapy, providing reasonable guidance for clinic application of CBCT in lung cancer.

METHODS

A total of 53 patients with lung carcinoma including 34 central and 19 peripheral lesions were collected in this study. Varian-IX linear accelerator on-board imaging (OBI) system was used to acquire CBCT scans in three-dimensional (3D) conformal radiotherapy before delivery. Different regions (whole lung/target/vertebrae/ipsilateral structure) were manually registered, and the position deviation and the registration time were analyzed.

RESULTS

It was suggested that 34 cases belonged to central type and 19 cases belonged to peripheral type. The volume of left lung and right lung was 1242.98 ± 452.46 cc, 1689.69 ± 574.31 cc, respectively. Tumor size was 6.65 ± 3.87 cm in diameter, and 129.67 ± 136.48 cc in volume. The percentage of left lung and right lung was 6.17 ± 1.24%, 4.74 ± 0.38%, respectively. The position deviation value and absolute value of image registration methods of X, Y and Z axis were not significant (P > 0.05). However, registration time (s) between whole lung registration group, tumor registration group, vertebral body registration group, affected lung registration group, and artificial registration group, was 3.651 ± 0.867 s, 1.144 ± 0.129 s, 1.226 ± 0.126 s, 2.081 ± 0.427 s, 179.491 ± 71.975 s, respectively. The differences were significant (P < 0.05). The registration differences between small tumor group and large tumor group were not statistically significant (P > 0.05).

CONCLUSION

The automatic image matching of OBI is accuracy and high reliability in recognition of offset error. Registering body or ipsilateral structure is recommended to be used in CBCT for lung cancer.

Diagnostic efficacy of cone beam computed tomography in paediatric dentistry: a systematic review

Purpose

To determine in which clinical situations it is indicated or contra-indicated to prescribe cone beam computed tomography (CBCT) for paediatric patients.

Methods

Systematic review of in vivo paediatric research studies of diagnostic efficacy using CBCT, with supplementary searches for guideline documents on CBCT and for systematic reviews permitting inclusion of ex vivo and adult studies.

Results

After screening, 190 publications were included, mostly case studies. No systematic reviews were found of in vivo paediatric research. Fourteen studies of diagnostic efficacy were identified. The supplementary searches found 18 guideline documents relevant to the review and 26 systematic reviews. The diagnostic efficacy evidence on CBCT was diverse and often of limited quality. There was ex vivo evidence for diagnostic accuracy being greater using CBCT than radiographs for root fractures. The multiplanar capabilities of CBCT are advantageous when localising dental structures for surgical planning. Patient movement during scanning is more common in children which could reduce diagnostic efficacy.

Conclusions

No strong recommendations on CBCT are possible, except that it should not be used as a primary diagnostic tool for caries. Guidelines on use of CBCT in the paediatric age group should be developed cautiously, taking into account the greater radiation risk and the higher economic costs compared with radiography. CBCT should only be used when adequate conventional radiographic examination has not answered the question for which imaging was required. Clinical research in paediatric patients is required at the higher levels of diagnostic efficacy of CBCT.

Electronic supplementary material

The online version of this article (10.1007/s40368-019-00504-x) contains supplementary material, which is available to authorized users.

Investigating the anatomical relationship between the maxillary molars and the sinus floor in a Chinese population using cone-beam computed tomography

Background

The anatomical relationship between the root apices of maxillary molars and the maxillary sinus floor (MSF) is important for the treatment of dental implantations and endodontic procedures. In this study, the detailed anatomical relationships between the root apices of maxillary molars and the MSF were studied in a Chinese population using CBCT.

Methods

We collected the CBCT data files of patients who visited the stomatology outpatient clinic in Shanghai Fifth People’s Hospital, Fudan University from January 1, 2017 to January 1, 2019 and measured the following items: the distance between the molar root apices and the MSF, the thickness of the mucosa and cortical bone of the MSF closest to the root apices, and the angle between the buccal and palatal roots.

Results

The shortest distances between the root apices and the MSF were 1.57 ± 3.33 mm (the mesiobuccal root of the left second molar) and 1.61 ± 3.37 mm (the mesiobuccal root of the right second molar). Apical protrusion over the inferior wall of the sinus most often occurred in the mesiobuccal root of left second molar (frequency, 20.5%). The mucosa of the MSF was thinnest at the distobuccal root of the right second molar (1.52 ± 0.85 mm), the cortical bone of the MSF was thinnest at the mesiobuccal root of the right second molar (0.46 ± 0.28 mm), and the angle between the buccal and palatal roots ranged from 12.01° to 124.2° (42.36 ± 24.33 °).

Conclusions

Among the root apices of the maxillary molars, the mesiobuccal root apex of the left second molar was closest to the MSF, and it had the highest incidence of protrusion into the sinus. The unique anatomical relationship between the maxillary molars and the MSF in this Chinese population is critical for treatment planning for dental implantation or endodontic procedures.

Radiation dose in cone beam CT guided ERCP

PURPOSE

To evaluate the practical and radiation safety considerations in utilization of 3-D imaging through cone beam computed tomography (CBCT) in endoscopic retrograde cholangiopancreatography (ERCP).

METHOD

ERCP procedures were performed using an Artis Q interventional suite (Siemens Healthineers), including 42 procedures with CBCT. Some CBCT cases used the standard "DR" exposure protocol and some used the low dose protocol "DR care". Data on x-ray radiation doses were retrospectively collected and to help optimize technical factors surrounding the procedure and compared to radiation exposure data of patients undergoing conventional ERCP.

RESULTS

The median dose area product was 24.4 Gycm² for one DR volume and 5.07 Gycm² for one DR care volume. The median total dose area product was 6.52 Gycm² for conventional ERCP, 48.9 Gycm² for procedures using DR and 19.7 Gycm² when using DR care. Conventional ERCP resulted in a significantly lower radiation dose than procedures using either CBCT protocols (p < 0.001). However, conventional ERCP showed a large number of outliers with higher dose at the level of, or surpassing, CBCT procedures.

CONCLUSIONS

For less complex procedures with small x-ray doses and short fluoroscopy times conventional 2-D x-ray technique is clinically sufficient and utilizes less radiation dose than CBCT methods, but there is a wide range of doses and extreme outliers have been observed. CBCT can facilitate ERCP in cases with difficult ducal anatomy, possibly reducing procedural time, x-ray exposure time and need for contrast injections. Methods for prediction on high radiation ERCPs are needed to standardize and optimize patient selection for CBCT-ERCP.

CBCT analysis of schneiderian membrane thickness and its relationship with gingival biotype and arch form

Objective

The purpose of this study was to investigate a relationship between gingival tissue biotypes and arch form with Schneiderian membrane thickness, using limited cone beam computed tomography.

Materials and Methods

A total of 90 subjects were selected. For each subject three parameters were assessed - gingival biotype - clinically by Probe transparency method as thin or thick and coded as 0 and 1, respectively, gingival thickness and Schneiderian membrane thickness in mm, arch form as square, oval, or tapered (radiographically by cone beam computed tomography images). Central incisors and first molars were assessed for gingival biotype and gingival thickness and Schneiderian membrane thickness was determined at 16. Numerical data were estimated for normal distribution. Analysis of Variance test was followed by Tukey honestly significant difference test and Pearson's correlation coefficient test for analysis.

Results

Thin gingival biotype was found associated with the central incisors and thick gingival biotype with molars. Limited cone beam computed tomography scans evaluation revealed highest prevalence of square arch form followed by oval, and tapered. The average thickness of the Schneiderian membrane was 1.18 ± 0.43 mm on left side and 1.09 ± 0.41 mm on right side with a range of 0.50 - 2.00 mm. Mean Schneiderian membrane thickness was more in case of thick gingival biotype and with square arc form both on right and left sides.

Conclusions

The Schneiderian membrane thickness was positively and highly associated with gingival biotype. The gingival biotype and arch form had significant effect on Schneiderian membrane thickness and can provide valuable clinical information on Schneiderian membrane thickness preoperatively for implant placement and sinus lift procedures.

Frequency of non-single canals in mandibular premolars and correlations with other anatomical variants: an in vivo cone beam computed tomography study

Background

A knowledge regarding anatomical variants is important to achieve success in endodontic treatment. Root canal treatment of mandibular first premolars (PM1 s) is challenging due to the existence of numerous variations in canal configurations, including a C-shaped variant. We aim to determine the frequency and morphologic characteristics of non-single canals of mandibular first (PM1 s) and second (PM2 s) premolars in a Korean population using cone beam computed tomography (CBCT) and to evaluate correlations between non-single canals of PM1 s and other anatomical variants, such as distolingual roots (DLRs) in mandibular first molars (M1 s) and C-shaped canals in mandibular second molars (M2 s).

Methods

A total of 971 PM1 s and 997 PM2 s from 500 patients were examined in vivo by CBCT. Root canal configurations and C-shaped canals were determined in accordance with the Vertucci classification and Fan classification, respectively. The correlation between non-single canals in PM1 s and DLRs in M1 s was evaluated using logistic regression analysis.

Results

PM2 s typically had one root (99.89%) with one canal (98.4%). Among PM1 s with non-single canals (21.2%), Vertucci type V (10.9%) and C-shaped (3.7%) canals were prevalent. Among C-shaped PM1 canals, the majority were Vertucci type V (77.8%); a C-shaped configuration (C2) was predominant mostly at the middle and/or apical third of the root. After adjusting for other variables (i.e., sex, age, and side), C-shaped canals in PM1 s was significantly correlated with the presence of DLRs in M1 s (odds ratio = 2.616; 95% confidence interval, 1.257–5.443; p = 0.010).

Conclusions

The presence of C-shaped PM1 canals was positively related to the presence of DLRs in M1 s. Although C-shaped canals in PM1 s are difficult to distinguish, this finding could aid clinicians in predicting C-shaped canal configurations in PM1 s of patients who exhibit DLRs in M1 s.

Morphometric analysis of nasopalatine foramen in Sri Lankan population using CBCT

Nasopalatine canal (NPC) is an important anatomical structure present in the anterior mid maxilla. It has the synonyms of incisive canal or anterior palatine canal. The objective of this study was to identify the morphometric characteristics of the NPC in group of Sri Lankan people using Cone beam computer tomography (CBCT) and to determine normal morphological course and anatomical variations. Fifty Maxillary CBCT images of anterior maxilla, obtained from the archives of the University Dental Hospital, Peradeniya were retrospectively analyzed to determine the position of the NPC. Morphology, canal dimension of NPC and its relation to the maxilla. Majority had a single opening (48%) or 2 openings (46%). Average diameter of the canal was 3.692 mm with a range of 2-6 mm. Majority of the canals had funnel shape and were vertically curved. Average length of canal was 12.142 mm and angulations of the curvature was 115.694⁰. Average antero-posterior diameter at nasal fossa was 2.852 mm, at mid-palate 2.366 mm and at hard palate 3.034 mm. Our findings were different from the findings reported in the literature. This may be due to the differences in ethnicity or limited size of sample. Within the limits of this study, we conclude that the form of the NPC is variable; predominantly funnel shaped with a single or two openings and with an average diameter of 3.7 mm in Sri Lankan population. Identification of variations in the position and shape will help in clinical practice specially in introducing local anesthetic block injections during dental treatment.

Assessment of the prelacrimal recess in maxillary sinus in different sex and age groups using cone beam computed tomography (CBCT)

BACKGROUND

The intranasal endoscopic prelacrimal recess approach (PLRA) to the maxillary sinus (MS) has been reported to treat many MS and skull base diseases. However, previous studies revealed that the width of the prelacrimal recess (PLR) shows a large individual variation. The purpose of this study was to ascertain the prevalence of the PLR in MS according to gender and age.

METHODS

A series of 701 maxillofacial cone beam computed tomography (CBCT) scans from adult patients were analyzed retrospectively. Patients were divided into five age groups (18-24 years, 25-34 years, 35-44 years, 45-54 years, and ≥ 55 years) and by sex. The frequencies of occurrence of the PLR in the MS were calculated and compared.

RESULTS

According to the findings obtained from our study, PLR was present in 81.5% of maxillary sinuses. No differences were found when the data distributions of right and left sides were compared. For individuals, the right and left sides were not always symmetrical. The probability of PLR was lesser among women than among men, but this differences was not significant. Another finding of our study was that the percentage of PLR decreased with increasing age among patients aged < 55 years, however, increased again among patients aged ≥ 55 years.

CONCLUSION

The anatomy of PLR varies among individuals. Careful analysis of individual anatomical structure characteristic is recommended when considering intranasal endoscopic PLRA to the MS. Besides, the age variation of PLR should be considered in order to avoid complications.

Assessment of condylar volume and ramus height in JIA patients with unilateral and bilateral TMJ involvement: retrospective case-control study

OBJECTIVES

The objectives of the study are to analyze volumetric differences of condylar volumes in patients with unilateral and bilateral JIA and to compare results with control condylar volumes.

MATERIALS AND METHODS

Forty-six CBCT images were analyzed for all patients affected by JIA, 37 females and 9 males (mean age 10.8 ± 4.2) with TMJ involvement (19 unilaterally, mean age 10.9 ± 4.5; 27 bilaterally, mean age 10.7 ± 4.5), and 25 CBCT of subjects without diagnosis of JIA were selected as controls (mean age 10.8 ± 4.2 years). In the case of unilateral JIA, condylar volumes and ramus lengths were compared with healthy condyle and with the compromised one. In the case of bilateral JIA, condyle volume and ramus lengths were compared with healthy one. The Shapiro-Wilk test was used to assess whether the data was normally distributed. Paired t test was applied to compare affected and non-affected condyle in the same patients (P < 0.05). Independent t test was used to evaluate whether the difference between the groups were comparable or significantly different (P < 0.05).

RESULTS

For the unilateral JIA group, significant differences comparing affected and non-affected condyles were found. A statistically significant reduction of the volume of the head, neck, and ramus was found in the affected side (P < 0.01). For the bilateral JIA group, statistically significant differences have been found considering the condylar head and neck, the whole condylar volume, and the ramus length compared with the control group (P < 0.05).

CONCLUSIONS

Subjects with unilateral JIA have condyles volumetrically smaller than those of the unaffected side and those found in healthy patients. A considerable decrease of the volume of all the anatomical structures considered in the patients with bilateral JIA was found compared with control group.

CLINICAL RELEVANCE

The study presents the effects of JIA on different anatomical structures highlighting their dimensional changes, whose sequelae are irreversible if not diagnosed and treated early.

Evaluation of the relationship between gonial angle and impacted mandibular third molar teeth

Mandibular third molar teeth have the highest impaction frequency for several reasons such as lack of space which may be related to the direction of facial growth. Gonial angle is used for the definition of facial growth pattern with some other measures such as mandibular plane angle. Winter and Pell-Gregory classifications are used for defining the level and pattern of mandibular third molar impaction. The aim of this study is to define the relationship between mandibular third molar impaction pattern and gonial angle; also to evaluate relationship between mandibular third molar roots and inferior alveolar canal. Study included 90 patients who had undergone cone beam computed tomography assessment for mandibular third molar impaction. Impacted teeth were grouped according to Pell-Gregory depth (A, B, C) and ramus (1, 2, 3) classification and sub-groups were composed. Winter classification was used for angulation of third molars and their relationship between with inferior alveolar canal was recorded. Gonial angle was measured on panoramic radiographs. Of the evaluated 90 impacted third molars, mesioangular position was the most frequent (34.4%), followed by vertical, horizontal and distoangular positions. Nearly 77% of the impacted third molar roots were related to inferior alveolar canal. While no correlation was determined between gender, age, third molar angulation and gonial angle, C2 sub-group of Pell-Gregory classification showed statistically significant higher gonial angle values. Although no significance was found, gonial angle was higher in level C group. In conclusion, gonial angle is higher in patients with C2 impaction level. Also, although statistically insignificant, Pell-Gregory C group had higher gonial angle averages.

Comparative evaluation of bone microstructure in alveolar cleft repair by cone beam CT: influence of different autologous donor sites and additional application of β-tricalcium phosphate

OBJECTIVES

This study used cone beam computed tomography (CBCT) images to comparatively evaluate the three-dimensional microstructural features of reconstructed bone bridge based on the bone harvesting site and the presence/absence of artificial bone material, as well as the features of regenerated bone tissue after bone harvesting from mandibular symphysis in secondary alveolar bone grafting (SABG) for patients with cleft lip, with or without cleft palate.

MATERIALS AND METHODS

Thirty-one patients were divided into three groups in which SABG was performed by autologous bone harvesting from iliac crest (IC), mandibular symphysis (MS), or MS combined with β-TCP granules (MS+TCP). The microstructural trabecular bone parameters (TBPs) and bone structure indexes (SIs) were analyzed using datasets of CBCT images taken before and after SABG.

RESULTS

TBPs showed differences between IC and MS groups (P < 0.05), resulting in greater values of bone volume density (P < 0.05) and inferior value of TBPf (P = 0.070) in IC group compared with MS group. Using MS+TCP or filling β-TCP granules into donor site significantly improved reconstructed or regenerated BV/TV and Tb.Th (P < 0.05) compared with group without β-TCP.

CONCLUSIONS

Microstructural characteristics of reconstructed bone bridge were dependent on the donor site of bone harvesting; using an absorbable bone conductive material improved bone quality and increased bone volume density.

CLINICAL RELEVANCE

Application of β-TCP granules as a partial alternative with autologous bone from mandibular symphysis could obtain comparable outcomes in the microstructure of bone bridge to SABG with autologous iliac crest.

Intrafractional motion in stereotactic body radiotherapy of spinal metastases utilizing cone beam computed tomography image guidance

Background and purpose

Spine stereotactic body radiotherapy (SBRT) requires a high degree of accuracy due to steep dose gradients close to the spinal cord. This study aimed to (1) evaluate intrafractional motion in spine SBRT utilizing flattening filter free (FFF) beam delivery and cone beam computed tomography (CBCT) image guidance and (2) evaluate if adding another CBCT acquisition and corrections prior to treatment improves the overall position accuracy.

Materials and methods

Intrafractional motion was retrospectively analyzed for 78 fractions in 54 patients. All patients were immobilized with an evacuated cushion. Before treatment, a CBCT was acquired, a bony fusion with the planning CT was performed and translational and rotational errors were corrected. For 30 of the patients (39 fractions) acquisition of another CBCT and corrections were performed before treatment. A post treatment CBCT was acquired for all patients, and translational and rotational errors measured by fusion of the post treatment CBCT with the planning CT were recorded to calculate means and standard deviations (SDs).

Results

The positional errors were significantly smaller in 4 out of 6 error values in the patient group treated with verification CBCT. In this group, translational and rotational SDs ranged from 0.5 to 0.6 mm and 0.3°, respectively. Corresponding values in the group treated without verification CBCT were 0.7-1.0 mm and 0.4-0.7°.

Conclusion

With proper CBCT image guidance, patient immobilization and FFF-beam delivery, one can obtain very high patient position accuracy in spine SBRT. Inclusion of a verification CBCT prior to treatment increases the overall position accuracy.