Comparative study of jaws with multislice computed tomography and cone-beam computed tomography

Tissue Expander Followed by Autogenous Bone Graft Versus Autogenous Bone Graft Alone for Mandibular Reconstruction: Quantitative Assessment

BACKGROUND

The use of a tissue expander in maxillofacial intraoral tissue reconstruction is a developing approach, which provide adequate tissue coverage and aesthetics.

OBJECTIVES

The purpose of this study was to quantitatively compare the use of a soft tissue expander in conjunction with autogenous bone graft with bone graft alone for the repair of the mandible's anterior region.

METHODS

The study comprised 24 patients with bone defects in the anterior mandibular region. Patients were divided into 2 groups at random. In group I, expander with bone graft was used, whereas in group II, bone graft was used alone. Volumetric measures of the grafted area was performed using CBCT, and cephalometric evaluations of the anteroposterior and vertical skeletal relationship, as well as the soft tissue profile were recoded. A comparison was made between the 2 groups 6 and 24 months after surgery with P ≤ 0.05 considered significant.

RESULTS

The mean difference in grafted bone volume between the 2 groups was 1.95 cm 3 , indicating a significant difference between the 2 groups ( P = 0.05) with superior group I results. The soft tissue profile of group I demonstrated a considerable improvement and stability of the lower lip, the labiomental sulcus, and the thickness of the soft tissue Pogonion compared with group II.

CONCLUSION

The use of a tissue expander in conjunction with a bone graft resulted in a better soft tissue profile, making it a favored approach in maxillofacial reconstruction.

Cone-beam computed tomography artifacts in the presence of dental implants and associated factors: an integrative review

Purpose

This study was conducted to review the literature regarding the types of cone-beam computed tomography (CBCT) artifacts around dental implants and the factors that influence their formation.

Materials and Methods

A search strategy was carried out in the PubMed, Embase, and Scopus databases to identify published between 2010 and 2020, and 9 studies were selected. The implants included 306 titanium, titanium-zirconium, and zirconia implants, as well as 5 titanium cylinders.

Results

The artifacts around the implants were the beam-hardening artifact, the streaking artifact, and band-like radiolucent areas. Some factors that influenced the formation of artifacts were the implant material, bone type, evaluated regions, distance, type of CBCT, field of view (FOV) size, milliamperage, peak kilovoltage (kVp), and voxel size. The beam-hardening artifact was the most widely reported, and it was minimized in protocols with a smaller FOV, larger voxels, and higher kVp.

Conclusion

The risk and benefit of these protocols in individuals with dental implants must be considered, and clinical examinations and complementary radiographs play an essential role in implantology.

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

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

Differences in the shape and direction-course of the nasopalatine canal among dentate, partially edentulous and completely edentulous subjects

We aimed to analyze the nasopalatine canal shape and anatomical variations of the buccal bone wall and compare the effect of the presence or absence of the central maxillary incisors on the nasopalatine canal. The shape of the nasopalatine canal and the dimensions of the buccal bone wall were measured in 150 patients who underwent a cone-beam computed tomography study. We found that the most prevalent shape of the nasopalatine canal was funnel (31%) and the most common direction-course was slanted-straight (33%). The buccal bone wall in relation to the nasopalatine canal was thickest at the anterior nasal spine level and narrowest at the level of the most anterior-inferior point of the buccal cortex of the maxilla. A statistically significant difference was detected between morphology and direction-course of the nasopalatine canal and dental status. In sum, the study of the nasopalatine canal showed multiple variations. Precise knowledge of these variations may help to decrease the incidence of complications during implantology treatment and during facial and dental surgery.

Clinical guidelines for dental cone-beam computed tomography

Dental cone-beam computed tomography (CBCT) received regulatory approval in Japan in 2000 and has been widely used since being approved for coverage by the National Health Insurance system in 2012. This imaging technique allows dental practitioners to observe and diagnose lesions in the dental hard tissue in three dimensions (3D). When performing routine radiography, the examination must be justified, and optimal protection should be provided according to the ALARA (as low as reasonably achievable) principles laid down by the International Commission on Radiological Protection. Dental CBCT should be performed in such a way that the radiation exposure is minimized and the benefits to the patient are maximized. There is a growing demand for widespread access to cutting-edge health care through Japan's universal health insurance system. However, at the same time, people want our limited human, material, and financial resources to be used efficiently while providing safe health care at the least possible cost to society. Japan's aging population is expected to reach a peak in 2025, when most of the baby boomer generation will be aged 75 years or older. Comprehensive health care networks are needed to overcome these challenges. Against this background, we hope that this text will contribute to the nation's oral health by encouraging efficient use of dental CBCT.

Assessment of Bone Dimensions in the Anterior Maxilla: A Cone Beam Computed Tomography Study

PURPOSE

To evaluate labial and palatal bone thickness at the maxillary anterior teeth as well as distance from cemento-enamel junction (CEJ) to bone crest using cone beam computed tomography (CBCT).

MATERIALS AND METHODS

Measurements were obtained for maxillary anterior teeth of 120 subject CBCT volumes including thickness of labial and palatal plates of bone (coronal, middle, and apical thirds), and distance between CEJ and alveolar bone crest mid-labially, mesially, and distally.

RESULTS

The mean value of bone thickness at coronal, middle, and apical thirds of the labial side for central incisor roots were respectively: 0.73, 0.69, 0.60 (mm), for lateral incisors: 0.70, 0.61, 0.49 (mm), and for canines: 0.74, 0.53, 040 (mm). The thickness of palatal bone was significantly larger. The mean distance between CEJ and mid-labial bone crest for all sites was 2.16 mm.

CONCLUSION

Labial bone thickness is thin in the vast majority of maxillary anterior teeth. Use of CBCT facilitates planning for immediate implant placement and is helpful in the decision-making process when further bone augmentation is needed.

Precision of cone beam CT to assess periodontal bone defects: a systematic review and meta-analysis

OBJECTIVES

Evaluate the diagnostic validity of CBCT in measuring periodontal bone defects when compared with the reference standard (in situ measurement).

METHODS

Studies in which the main objective was to evaluate the diagnostic validity of CBCT in measuring periodontal bone defects when compared with the reference standard were selected. Four databases were searched. The studies were selected by two independent reviewers. The methodology of selected studies was assessed using the 14-item Quality Assessment Tool for Diagnostic Accuracy Studies. The quality of evidence and strength of recommendation was assessed by The Grading of Recommendations Assessment Tool, Development and Evaluation.

RESULTS

Using a selection process in two phases, 16 studies were identified and, in seven articles meta-analysis was performed. The results from these meta-analyses showed that no difference between the measurements of CBCT and in situ for alveolar bone loss, and demonstrated a concordance of 82.82% between CBCT and in situ for the classification of the degree of furcation involvement.

CONCLUSIONS

Based on a moderate level of evidence, CBCT could be useful for furcation involvement periodontal cases, but it should only be used in cases where clinical evaluation and conventional radiographic imaging do not provide the information necessary for an adequate diagnosis and proper periodontal treatment planning.

Artifacts in orthodontic bracket systems in cone-beam computed tomography and multislice computed tomography

OBJECTIVES

The purpose of this study was to quantify artifacts caused by different bracket systems in cone-beam computed tomography (CBCT) and multislice computed tomography (MSCT) scans.

METHODS

Orthodontic brackets of four different systems were consecutively bonded to the surface of a residual molar on a human cadaveric mandible. One MSCT system and three CBCT units were used to scan each of the four bonded brackets, in addition to obtaining a blank reference scan of the tooth surface. All datasets were registered to the reference dataset using visualization software (Analyze 11.0® by AnalyzeDirect). Artifact-related reductions in image quality were expressed in percent of theoretical maximum standard deviations (SD) obtained for the gray values of the adjacent voxels, with higher percentages correlating more pronounced artifacts.

RESULTS

Both the SD percentages for three defined line profiles and their mean values were almost invariably higher with the MSCT system than with the CBCT units. Looking into the individual SD percentages, two of the CBCT units (Pax Zenith 3D® and Picasso Trio®; both Vatech) produced higher values than the MSCT system (SOMATOM Definition AS+®; Siemens) in some line profiles. The titanium bracket, in particular, was associated with marked differences between the two scanner technologies, as the mean artifact intensities from this bracket were particularly high with the MSCT unit and relatively low with the CBCT units. The artifact intensities observed with the other three bracket systems varied widely depending on which scanner was used.

CONCLUSION

Different artifact intensities were noted depending on the composition of the bracket system and on the scanner technology (MSCT/CBCT). While the artifacts manifested themselves differently with different scanners, their adverse effects were comparable. However, given the variable severity of the artifacts observed depending on the materials scanned and the scanners used, a blanket recommendation for or against MSCT or CBCT units cannot be given on the basis of this study.

Anterior maxilla alveolar ridge dimension and morphology measurement by cone beam computerized tomography (CBCT) for immediate implant treatment planning

Background

Implants have been widely used to restore missing teeth. Limited information on applied anatomy at the anterior maxilla compromises the clinical outcome for implant placement in this region. In the current study, Cone Beam Computerized Tomography (CBCT) was used to measure alveolar ridge and buccal undercut dimension at the anterior maxilla to help develop treatment planning for immediate implant placement.

Methods

CBCT scans were screened to include 51 subjects with full dentition at right maxilla. Measurements were taken at the cross sectional views in the middle of the maxillary right central incisor, lateral incisor, and canine regions. Alveolar height was measured from the alveolar crest to floor of nasal fossa. Alveolar width was measured from the buccal to palatal cortical plate at the coronal, middle, and apical third of the distance from the alveolar crest to floor of the nasal fossa. Buccal undercut location was measured from where the buccal cortical plate started dipping to a line extending at the alveolar crest that was perpendicular to the long axis of the alveolar ridge. The buccal undercut depth was measured from the deepest point of the undercut at the buccal plate to a line tangent to the buccal plate paralleling the long axis of ridge.

Results

Alveolar width increased from coronal to apical direction for each tooth. Mean alveolar widths (mm) were: central incisor, 9.55; lateral incisor, 8.30; canine, 9.62. The lateral incisor had a significantly smaller alveolar width than the other anterior teeth. No significant difference in ridge height was noted among the teeth. Undercut locations from the alveolar crest (mm) were: central incisor, 5.84; lateral incisor, 3.59; canine, 5.11. Undercut depths (mm) were: central incisor, 0.76; lateral incisor, 0.87; canine, 0.73. The percentages of teeth with buccal undercuts were: central incisor, 41 %, lateral incisor, 77 %, and canine 33 %. Male demonstrate significant larger ridge width compared with females for all three teeth.

Conclusions

At anterior maxilla, the lateral incisor has the thinnest alveolar bone, and most frequently exhibits a buccal undercut which is the closest to alveolar ridge compared with other maxillary anterior teeth.

Comparison of cone-beam CT-guided and CT fluoroscopy-guided transthoracic needle biopsy of lung nodules

PURPOSE

To compare the diagnostic performance of cone-beam CT (CBCT)-guided and CT fluoroscopy (fluoro-CT)-guided technique for transthoracic needle biopsy (TNB) of lung nodules.

METHODS

The hospital records of 319 consecutive patients undergoing 324 TNBs of lung nodules in a single radiology unit in 2009-2013 were retrospectively evaluated. The newly introduced CBCT technology was used to biopsy 123 nodules; 201 nodules were biopsied by conventional fluoro-CT-guided technique. We assessed the performance of the two biopsy systems for diagnosis of malignancy and the radiation exposure.

RESULTS

Nodules biopsied by CBCT-guided and by fluoro-CT-guided technique had similar characteristics: size, 20 ± 6.5 mm (mean ± standard deviation) vs. 20 ± 6.8 mm (p = 0.845); depth from pleura, 15 ± 15 mm vs. 15 ± 16 mm (p = 0.595); malignant, 60% vs. 66% (p = 0.378). After a learning period, the newly introduced CBCT-guided biopsy system and the conventional fluoro-CT-guided system showed similar sensitivity (95% and 92%), specificity (100% and 100%), accuracy for diagnosis of malignancy (96% and 94%), and delivered non-significantly different median effective doses [11.1 mSv (95 % CI 8.9-16.0) vs. 14.5 mSv (95% CI 9.5-18.1); p = 0.330].

CONCLUSION

The CBCT-guided and fluoro-CT-guided systems for lung nodule biopsy are similar in terms of diagnostic performance and effective dose, and may be alternatively used to optimize the available technological resources.

KEY POINTS

• CBCT-guided and fluoro-CT-guided lung nodule biopsy provided high and similar diagnostic accuracy. • Effective dose from CBCT-guided and fluoro-CT-guided lung nodule biopsy was similar. • To optimize resources, CBCT-guided lung nodule biopsy may be an alternative to fluoro-CT-guided.

Effective dose of cone beam CT (CBCT) of the facial skeleton: a systematic review

OBJECTIVE

To estimate effective dose of cone beam CT (CBCT) of the facial skeleton with focus on measurement methods and scanning protocols.

METHODS

A systematic review, which adhered to the preferred reporting items for systematic reviews (PRISMA) Statement, of the literature up to April 2014 was conducted. Data sources included MEDLINE®, The Cochrane Library and Web of Science. A model was developed to underpin data extraction from 38 included studies.

RESULTS

Technical specifications of the CBCT units were insufficiently described. Heterogeneity in measurement methods and scanning protocols between studies made comparisons of effective doses of different CBCT units and scanning protocols difficult. Few studies related doses to image quality. Reported effective dose varied across studies, ranging between 9.7 and 197.0 μSv for field of views (FOVs) with height ≤5 cm, between 3.9 and 674.0 μSv for FOVs of heights 5.1-10.0 cm and between 8.8 and 1073.0 μSv for FOVs >10 cm. There was an inconsistency regarding reported effective dose of studies of the same CBCT unit with the same FOV dimensions.

CONCLUSION

The review reveals a need for studies on radiation dosages related to image quality. Reporting quality of future studies has to be improved to facilitate comparison of effective doses obtained from examinations with different CBCT units and scanning protocols. A model with minimum data set on important parameters based on this observation is proposed.

ADVANCES IN KNOWLEDGE

Data important when estimating effective dose were insufficiently reported in most studies. A model with minimum data based on this observation is proposed. Few studies related effective dose to image quality.

Intravenous contrast media application using cone-beam computed tomography in a rabbit model

Purpose

This study was performed to evaluate the feasibility of visualizing soft tissue lesions and vascular structures using contrast-enhanced cone-beam computed tomography (CE-CBCT) after the intravenous administration of a contrast medium in an animal model.

Materials and Methods

CBCT was performed on six rabbits after a contrast medium was administered using an injection dose of 2 mL/kg body weight and an injection rate of 1 mL/s via the ear vein or femoral vein under general anesthesia. Artificial soft tissue lesions were created through the transplantation of autologous fatty tissue into the salivary gland. Volume rendering reconstruction, maximum intensity projection, and multiplanar reconstruction images were reconstructed and evaluated in order to visualize soft tissue contrast and vascular structures.

Results

The contrast enhancement of soft tissue was possible using all contrast medium injection parameters. An adequate contrast medium injection parameter for facilitating effective CE-CBCT was a 5-mL injection before exposure combined with a continuous 5-mL injection during scanning. Artificial soft tissue lesions were successfully created in the animals. The CE-CBCT images demonstrated adequate opacification of the soft tissues and vascular structures.

Conclusion

Despite limited soft tissue resolution, the opacification of vascular structures was observed and artificial soft tissue lesions were visualized with sufficient contrast to the surrounding structures. The vascular structures and soft tissue lesions appeared well delineated in the CE-CBCT images, which was probably due to the superior spatial resolution of CE-CBCT compared to other techniques, such as multislice computed tomography.

Accuracy of surgical guides made from conventional and a combination of digital scanning and rapid prototyping techniques

STATEMENT OF PROBLEM

Surgical guides aid in accurately placing dental implants to achieve a predictable restorative outcome. Which surgical guide fabrication technique results in the most accurately fitting surgical guide is unknown.

PURPOSE

The purpose of this investigation was to determine the internal fit of dental implant surgical guides on dentate and edentulous ridges by using implant surgical guides fabricated from conventional and computer-aided design/computer-aided manufacturing (CAD/CAM) techniques.

MATERIAL AND METHODS

Eighty surgical guides were fabricated from conventional and CAD/CAM techniques; half were designed from Kennedy Class 2 (K2) casts, and half were designed from Kennedy Class 3 (K3) casts. Conventional surgical guides were fabricated from acrylic resin. The CAD/CAM surgical guides were scanned by using cone beam computed tomography (CBCT) or an optical scan (OS). The guides were printed with stereolithography (SL) or 3-dimensional digital printing (3DP). All surgical guides were cemented to their respective design casts, sectioned, and measured at standardized locations. A 2-way ANOVA and the post hoc Fisher least square difference t test was performed (α=.05).

RESULTS

The 2-way ANOVA indicated that the difference between surgical guide groups and Kennedy class was statistically significant (P<.05) and the interaction between groups and Kennedy class was statistically significant (P<.05). The OS/3DP CAD/CAM guide was the best-fitting cast for the K2 cast group, and the conventional guide was the best-fitting guide for the K3 group.

CONCLUSIONS

Conventionally fabricated and OS surgical guides have greater accuracy of fit than CBCT scanned surgical guides.

Cone beam computed tomography and low-dose multislice computed tomography in orthodontics and dentistry: a comparative evaluation on image quality and radiation exposure

OBJECTIVES

The goal of the present work was to assess various computed tomography (CT) systems in term of image quality and organ doses, namely five cone-beam CT (CBCT) scanners operated at standard settings and three multislice CT (MSCT) scanners operated at greatly dose-reduced settings.

MATERIALS AND METHODS

Radiographic volume scans were taken on a complete human cadaveric head specimen and the image quality of each was rated by four experienced examiners according to specific skeletal structures and bone-soft tissue interfaces. Radiation doses were captured by a head-and-neck phantom (Rando; Alderson Research Laboratories). Standard protocols were used for the CBCT scans. For the MSCT scans, tube voltage and current were adjusted to minimize radiation without compromising image quality.

RESULTS

Interobserver agreement was close to perfect, with iota coefficients of 0.931 (95% CI 0.807-0.978) between groups 1 and 2 and 0.959 (95% CI 0.869-1.000) between groups 1 and 3. Ratings of image quality in terms of skeletal-structure representation were slightly better for the CBCT than the MSCT scanners, although these differences were not statistically significant. The two groups of scanners applied considerably different organ doses: the lowest dose (0.03 mSv) was measured on the bone surface with a CBCT unit (Picasso Trio® from Vatech) and the highest dose (8.30 mSv) in the vicinity of the eye lens with another CBCT unit (3D Accuitomo 170® from J. Morita).

CONCLUSION

The various systems tested offer similar imaging quality but demonstrated distinct differences in organ dose levels. The decision on which approach to take is not between CBCT and MSCT but rather between specific models and parameter settings. If these are optimized, MSCT images providing useful clinical information can be obtained at much reduced levels of radiation. Depending on the model and setting used, MSCT radiation levels may even be lower than during CBCT scans.

Impact of cone-beam computed tomography on implant planning and on prediction of implant size

The aim was to investigate the impact of cone-beam computed tomography (CBCT) on implant planning and on prediction of final implant size. Consecutive patients referred for implant treatment were submitted to clinical examination, panoramic (PAN) radiography and a CBCT exam. Initial planning of implant length and width was assessed based on clinical and PAN exams, and final planning, on CBCT exam to complement diagnosis. The actual dimensions of the implants placed during surgery were compared with those obtained during initial and final planning, using the McNemmar test (p < 0.05). The final sample comprised 95 implants in 27 patients, distributed over the maxilla and mandible. Agreement in implant length was 50.5% between initial and final planning, and correct prediction of the actual implant length was 40.0% and 69.5%, using PAN and CBCT exams, respectively. Agreement in implant width assessment ranged from 69.5% to 73.7%. A paired comparison of the frequency of changes between initial or final planning and implant placement (McNemmar test) showed greater frequency of changes in initial planning for implant length (p < 0.001), but not for implant width (p = 0.850). The frequency of changes was not influenced by implant location at any stage of implant planning (chi-square test, p > 0.05). It was concluded that CBCT improves the ability of predicting the actual implant length and reduces inaccuracy in surgical dental implant planning.

Long-term effects of antihypertensive medications on bone mineral density in men older than 55 years

Introduction

In this study, we investigated the effects of long-term antihypertensive treatment with calcium channel blockers or beta blockers on the bone mineral density of maxilla, as determined by cone-beam computed tomography (CBCT).

Material and methods

This retrospective study was conducted on CBCT images of men older than 55 years who had received different dental indications. Data were grouped into three categories according to the antihypertensive medication history of the patients: group A included patients who had been taking beta-blocker treatment for more than 5 years, group B included patients who had been taking calcium channel blocker treatment for more than 5 years, and the control group included patients who had never used any hypertensive medications before.

Results

Statistically significant differences were observed between the beta blocker and calcium channel blocker groups.

Conclusion

In hypertension treatment, beta blockers may be preferred to calcium channel blockers in patients at high risk for osteoporosis and bone resorption.

Reduction of dark-band-like metal artifacts caused by dental implant bodies using hypothetical monoenergetic imaging after dual-energy computed tomography

OBJECTIVE

The aim of this study was to evaluate the usefulness of hypothetical monoenergetic images after dual-energy computed tomography (DECT) for assessment of the bone encircling dental implant bodies.

STUDY DESIGN

Seventy-two axial images of implantation sites clipped out from image data scanned using DECT in dual-energy mode were used. Subjective assessment on reduction of dark-band-like artifacts (R-DBAs) and diagnosability of adjacent bone condition (D-ABC) in 3 sets of DECT images-a fused image set (DE120) and 2 sets of hypothetical monoenergetic images (ME100, ME190)-was performed and the results were statistically analyzed.

RESULTS

With regards to R-DBAs and D-ABC, significant differences among DE120, ME100, and ME190 were observed. The ME100 and ME190 images revealed more artifact reduction and diagnosability than those of DE120.

CONCLUSIONS

DECT imaging followed by hypothetical monoenergetic image construction can cause R-DBAs and increase D-ABC and may be potentially used for the evaluation of postoperative changes in the bone encircling implant bodies.

Bone quality evaluation at dental implant site using multislice CT, micro-CT, and cone beam CT

OBJECTIVES

The first purpose of this study was to analyze the correlation between bone volume fraction (BV/TV) and calibrated radiographic bone density Hounsfield units (HU) in human jaws, derived from micro-CT and multislice computed tomography (MSCT), respectively. The second aim was to assess the accuracy of cone beam computed tomography (CBCT) in evaluating trabecular bone density and microstructure using MSCT and micro-CT, respectively, as reference gold standards.

MATERIAL AND METHODS

Twenty partially edentulous human mandibular cadavers were scanned by three types of CT modalities: MSCT (Philips, Best, the Netherlands), CBCT (3D Accuitomo 170, J Morita, Kyoto, Japan), and micro-CT (SkyScan 1173, Kontich, Belgium). Image analysis was performed using Amira (v4.1, Visage Imaging Inc., Carlsbad, CA, USA), 3Diagnosis (v5.3.1, 3diemme, Cantu, Italy), Geomagic (studio(®) 2012, Morrisville, NC, USA), and CTAn (v1.11, SkyScan). MSCT, CBCT, and micro-CT scans of each mandible were matched to select the exact region of interest (ROI). MSCT HU, micro-CT BV/TV, and CBCT gray value and bone volume fraction of each ROI were derived. Statistical analysis was performed to assess the correlations between corresponding measurement parameters.

RESULTS

Strong correlations were observed between CBCT and MSCT density (r = 0.89) and between CBCT and micro-CT BV/TV measurements (r = 0.82). Excellent correlation was observed between MSCT HU and micro-CT BV/TV (r = 0.91). However, significant differences were found between all comparisons pairs (P < 0.001) except for mean measurement between CBCT BV/TV and micro-CT BV/TV (P = 0.147).

CONCLUSIONS

An excellent correlation exists between bone volume fraction and bone density as assessed on micro-CT and MSCT, respectively. This suggests that bone density measurements could be used to estimate bone microstructural parameters. A strong correlation also was found between CBCT gray values and BV/TV and their gold standards, suggesting the potential of this modality in bone quality assessment at implant site.

The occurrence of dental caries is associated with atherosclerosis

OBJECTIVE

Previous studies have suggested that marginal periodontitis is a risk factor for developing atherosclerosis. The objective of this study was to determine whether caries may also be associated with atherosclerosis.

METHODS

The computed tomography data sets of 292 consecutive patients, 137 women and 155 men with a mean age of 54.1±17.3 years, were analyzed. Caries were quantified based on the number of decayed surfaces of all the teeth, and periodontitis was quantified on the basis of the horizontal bone loss in the jaw. The presence of chronic apical periodontitis (CAP) was assessed, and the aortic atherosclerotic burden was quantified using a calcium scoring method.

RESULTS

The patients with <1 caries surfaces/tooth had a lower atherosclerotic burden (0.13±0.61 mL) than patients with ≥1 caries surfaces/tooth. The atherosclerotic burden was greater in patients with a higher number of lesions with pulpal involvement and more teeth with chronic apical periodontitis. In the logistical regression models, age (Wald 49.3), number of caries per tooth (Wald 26.4), periodontitis (Wald 8.6), and male gender (Wald 11) were found to be independent risk factors for atherosclerosis. In the linear regression analyses, age and the number of decayed surfaces per tooth were identified as influencing factors associated with a higher atherosclerotic burden, and the number of restorations per tooth was associated with a lower atherosclerotic burden.

CONCLUSION

Dental caries, pulpal caries, and chronic apical periodontitis are associated positively, while restorations are associated inversely, with aortic atherosclerotic burden. Prospective studies are required to confirm these observations and answer the question of possible causality.

Three-dimensional linear and volumetric analysis of maxillary sinus pneumatization

Considering the anatomical variability related to the maxillary sinus, its intimate relation to the maxillary posterior teeth and because of all the implications that pneumatization may possess, three-dimensional assessment of maxillary sinus pneumatization is of most usefulness. The aim of this study is to analyze the maxillary sinus dimensions both linearly and volumetrically using cone beam computed tomography (CBCT) to assess the maxillary sinus pneumatization. Retrospective analysis of 30 maxillary sinuses belonging to 15 patients’ CBCT scans was performed. Linear and volumetric measurements were conducted and statistically analyzed. The maximum craniocaudal extension of the maxillary sinus was located around the 2nd molar in 93% of the sinuses, while the maximum mediolateral and antroposterior extensions of the maxillary sinus were located at the level of root of zygomatic complex in 90% of sinuses. There was a high correlation between the linear measurements of the right and left sides, where the antroposterior extension of the sinus at level of the nasal floor had the largest correlation (0.89). There was also a high correlation between the Simplant and geometric derived maxillary sinus volumes for both right and left sides (0.98 and 0.96, respectively). The relations of the sinus floor can be accurately assessed on the different orthogonal images obtained through 3D CBCT scan. The geometric method offered a much cheaper, easier, and less sophisticated substitute; therefore, with the availability of software, 3D volumetric measurements are more facilitated.

A new method to evaluate volumetric changes in sinus augmentation procedure

BACKGROUND

In sinus augmentation procedure, the assessment of volume changes of grafted materials is important both in the clinical practice and in dental research to evaluate the features of filling materials.

PURPOSE

In this study, we assessed the repeatability of a new method proposed to evaluate volumetric changes following sinus lift augmentation procedure.

MATERIALS AND METHODS

In 10 patients, maxillary sinus augmentation procedure with simultaneous implant placement was performed. Maxillary cone beam computer tomographies were taken 1 week after surgery (T1) and 6 months after surgery (T2). At each evaluation the gap inside the implant between the fixture and the bottom of the screw was used as reference point (Rp), and a standardized volume of interest (VOI) centered on the Rp was selected. Masks were chosen to select the graft and bone tissue within the VOI; the volume at T1, T2, and the difference of volume between T1 and T2 were computed. Expert and non-expert operators performed the analysis. Method errors were computed.

RESULTS

The error of the method was 1% for both intra-operator and inter-operator measurements. Tissue contraction at T2 was 19 ± 4% of the total initial volume.

CONCLUSIONS

The standardization of the method allows to obtain repeatable measurements.

Comparative study of image quality and radiation dose of cone beam and low-dose multislice computed tomography--an in-vitro investigation

OBJECTIVES

The aim of this study was to evaluate the image quality and dose exposition of different cone-beam computed tomography (CBCT) and low-dose multislice spiral CT (MSCT) scanners.

MATERIALS AND METHODS

A human cadaver head was examined with three MSCT and five CBCT scanners. The radiation dose was measured using an Alderson RANDO phantom. Standard protocols were used to obtain the CBCT data. For the MSCT devices, the tube voltage and tube current were modified to obtain acceptable image quality while keeping the radiation dose as low as possible. The image quality of MSCT and CBCT devices was determined by examining the enamel-dentin and dentin-pulp interface and the periodontal ligament space of 22 teeth.

RESULTS

Inter- and intra-observer agreement was found for the different groups of raters. CBCT systems were rated superior to MSCT devices in terms of image quality for all dental structures. The differences in image quality among the studied CBCT and MSCT scanner groups did not turn out to be significant but were significant between CBCT and MSCT devices. The organ dose varied considerably between the different CBCT and MSCT devices. The differences concerning the organ dose were notably pronounced in the area of the eye lens.

CONCLUSIONS

The tested devices exhibited significant differences with respect to the organ dose. The variance was particularly pronounced in the CBCT devices. With a dose exposition equal or lower than the CBCT, the image quality in the MSCT devices was judged to be significantly worse.

Multidetector CT Dentascan evaluation of bone regeneration obtained with deproteinised bovine graft in residual cavity after mandibular cyst enucleation

PURPOSE

This study compared spontaneous bone healing and regeneration obtained with deproteinised bovine graft in residual cavities after mandibular cyst enucleation using computed tomography (CT) Dentascan.

MATERIALS AND METHODS

Eighty patients with a radiological diagnosis of mandibular cyst underwent surgical enucleation. Patients were divided into a control group (spontaneous healing, 40 patients) and a test group (deproteinised bovine graft, 40 patients). All patients underwent follow-up CT Dentascan 12 months after the procedure. For each residual cavity, apical-coronal and mesial-distal distance, average pixel intensity and volume were calculated and results compared between two groups using the t test.

RESULTS

The control group showed mean volume, apical-coronal and mesial-distal distance of 703.2 ± 185.3 mm(3), 28.6 ± 9.4 mm and 25 ± 2.84 mm, respectively. In the test group, values were 738.2 ± 189.2 mm(3), 27.5 ± 3.6 mm and 25.3 ± 2.97 mm, respectively. There was no statistically significant difference between groups. Average pixel intensity was 1,102.8 ± 124.3 in the test group and 624.9 ± 133.3 in the control group, with a significant difference between groups (p<0.0001).

CONCLUSIONS

The significantly higher average pixel intensity observed in the test group demonstrates the cavalue of treatment with biomaterials to obtain earlier bone regeneration.

Cone beam CT evaluation of maxillary sinus septa prevalence, height, location and morphology in children and an adult population

OBJECTIVE

The purpose of this study was to determine the prevalence, height, location and morphology of maxillary sinus septa in dentate, partially dentate and edentulous adults as well as in mixed dentition children using cone beam computed tomography (CBCT) for maxillary sinus surgical interventions.

SUBJECTS AND METHODS

Five hundred and fifty-four sides in the CBCT scans of 272 patients (30 children and 242 adults) were retrospectively analyzed. The prevalence, location and morphology were assessed in axial, sagittal, cross-sectional and panoramic 3-dimensional images. The height of septa was measured with the angle between the direction of the septum and median palatine suture. The differences among age, localization and measurements were statistically analyzed.

RESULTS

The prevalence of maxillary sinus segments with septa was 58%. There were a total of 13 (3.2%) septa of completely edentulous (CE), 198 (53.9%) septa of edentate and 14 (3.8%) septa of the mixed dentition maxillary segments. The location of septa observed in all study groups demonstrated a greater prevalence (69.1%) in the middle region than in the anterior and posterior regions. No statistically significant differences were observed with regard to gender or age, for septum height (p > 0.05). However, maxillary sinus septa are higher in partially edentulous patients than edentate and CE ones (p < 0.05).

CONCLUSION

Septa of various heights and courses developed in all parts of the maxillary sinus, therefore to prevent possible complications during sinus surgery, extensive evaluation with an appropriate radiographic technique was indispensable.

Large arteriovenous malformation of the oromaxillofacial region with multiple phleboliths

Vascular tumors are the most common benign tumors of the head and neck in infancy and childhood. Vascular anomalies of the head and neck were divided into 2 categories including hemangiomas and vascular malformations. Oral and maxillofacial hemangiomas and vascular malformations are congenital lesions with various clinical characteristics, manifestations, indications, and possibilities for treatment. This paper reports a case of large arteriovenous malformations including a description of the features demonstrated by panoramic radiography, cone beam computed tomography, and magnetic resonance imaging. The differential diagnosis and treatment modalities (including embolization with N-butylcyanoacrylate in this case) are also discussed following the case presentation, along with the available literature review.

Influence of cone beam CT scanning parameters on grey value measurements at an implant site

OBJECTIVES

The aim of this study was to determine the grey value variation at the implant site with different scan settings, including field of view (FOV), spatial resolution, number of projections, exposure time and dose selections in two cone beam CT (CBCT) systems and to compare the results with those obtained from a multislice CT system.

METHODS

A partially edentulous human mandibular cadaver was scanned by three CT modalities: multislice CT (MSCT) (Philips, Best, the Netherlands), and two CBCT systems: (Accuitomo 170(®), Morita, Japan) and (NewTom 5G(®), QR, Verona, Italy). Using different scan settings 36 and 24 scans were obtained from the Accuitomo and the NewTom, respectively. The scans were converted to digital imaging and communications in medicine 3 format. The analysis of the data was performed using 3Diagnosys(®) software (v. 3.1, 3diemme, Cantù, Italy) and Geomagic studio(®) 2012 (Morrisville, NC). On the MSCT scan, one probe designating the site for pre-operative implant placement was inserted. The inserted probe on MSCT was transformed to the same region on each CBCT scan using a volume-based three-dimensional registration algorithm. The mean voxel grey value of the region around the probe was derived separately for each CBCT. The influence of scanning parameters on the measured mean voxel grey values was assessed.

RESULTS

Grey values in both CBCT systems significantly deviated from Hounsfield unit values measured with MSCT (p = 0.0001). In both CBCT systems, scan FOV and spatial resolution selections had a statistically significant influence on grey value measurements (p = 0.0001). The number of projections selection had a statistically significant influence in the Accuitomo system (p = 0.0001) while exposure time and dose selections had no statistically significant influence on grey value measurements in the NewTom (p = 0.43 and p = 0.37, respectively).

CONCLUSIONS

Grey-level values from CBCT images are influenced by device and scanning settings.

Comparison of effective dose for imaging of mandible between multi-detector CT and cone-beam CT

Purpose

The aim of this study was to compare the effective dose for imaging of mandible between multi-detector computed tomography (MDCT) and cone-beam computed tomography (CBCT). An MDCT with low dose technique was also compared with them.

Materials and Methods

Thermoluminescent dosimeter (TLD) chips were placed at 25 organ sites of an anthropomorphic phantom. The mandible of the phantom was exposed using 2 different types of MDCT units (Somatom Sensation 10 for standard-dose MDCT, Somatom Emotion 6 for low-dose MDCT) and 3 different CBCT units (AZ3000CT, Implagraphy, and Kavo 3D eXaM). The radiation absorbed dose was measured and the effective dose was calculated according to the ICRP 2007 report.

Results

The effective dose was the highest for Somatom Sensation 10 (425.84 µSv), followed by AZ3000CT (332.4 µSv), Somatom Emotion 6 (199.38 µSv), and 3D eXaM (111.6 µSv); it was the lowest for Implagraphy (83.09 µSv). The CBCT showed significant variation in dose level with different device.

Conclusion

The effective doses of MDCTs were not significantly different from those of CBCTs for imaging of mandible. The effective dose of MDCT could be markedly decreased by using the low-dose technique.

Construction of orthodontic setup models on a computer

INTRODUCTION

Orthodontic setup models are usually limited to the display of teeth, with no information about the roots. The purpose of this article is to present a method for visualizing the tooth roots in setup models by integrating information from cone-beam computed tomography and a laser scanner. The reproducibility of the integration was evaluated.

METHODS

The records of 5 patients were used in this study. Three-dimensional digital models were generated from the dental casts. Tooth models were generated from the cone-beam computed tomography slices. The 3-dimensional models were superimposed on the crowns of the teeth in the tooth models and integrated. The integrated 3-dimensional tooth model and 3-dimensional setup model were registered. The reproducibility of the integration was evaluated for each tooth. Unpaired Student t tests were performed on the data between the anterior and posterior teeth, and between the right and left teeth.

RESULTS

The discrepancy among the integrated 3-dimensional models at the final positions after we used this technique was 0.025 ± 0.007 mm. There was a significant difference in the distance between the anterior and posterior teeth (P <0.05). However, the average distances between the anterior and posterior teeth were small: 0.023 ± 0.007 and 0.028 ± 0.007 mm, respectively. No significant difference was found between the right and left teeth (P = 0.831).

CONCLUSIONS

The methods presented in this study provide a reproducible visualization of tooth roots in virtual setup models by registering accurate crown models to cone-beam computed tomography scans.

Accuracy of linear intraoral measurements using cone beam CT and multidetector CT: a tale of two CTs

OBJECTIVES

The aim was to compare the accuracy of linear bone measurements of cone beam CT (CBCT) with multidetector CT (MDCT) and validate intraoral soft-tissue measurements in CBCT.

METHODS

Comparable views of CBCT and MDCT were obtained from eight intact cadaveric heads. The anatomical positions of the gingival margin and the buccal alveolar bone ridge were determined. Image measurements (CBCT/MDCT) were performed upon multiplanar reformatted data sets and compared with the anatomical measurements; the number of non-assessable sites (NASs) was evaluated.

RESULTS

Radiological measurements were accurate with a mean difference from anatomical measurements of 0.14 mm (CBCT) and 0.23 mm (MDCT). These differences were statistically not significant, but the limits of agreement for bone measurements were broader in MDCT (-1.35 mm; 1.82 mm) than in CBCT (-0.93 mm; 1.21 mm). The limits of agreement for soft-tissue measurements in CBCT were smaller (-0.77 mm; 1.07 mm), indicating a slightly higher accuracy. More NASs occurred in MDCT (14.5%) than in CBCT (8.3%).

CONCLUSIONS

CBCT is slightly more reliable for linear measurements than MDCT and less affected by metal artefacts. CBCT accuracy of linear intraoral soft-tissue measurements is similar to the accuracy of bone measurements.

Effect of electric potential and current on mandibular linear measurements in cone beam CT

OBJECTIVES

The purpose of this study was to compare mandibular linear distances measured from cone beam CT (CBCT) images produced by different radiographic parameter settings (peak kilovoltage and milliampere value).

METHODS

20 cadaver hemimandibles with edentulous ridges posterior to the mental foramen were embedded in clear resin blocks and scanned by a CBCT machine (CB MercuRay(TM); Hitachi Medico Technology Corp., Chiba-ken, Japan). The radiographic parameters comprised four peak kilovoltage settings (60 kVp, 80 kVp, 100 kVp and 120 kVp) and two milliampere settings (10 mA and 15 mA). A 102.4 mm field of view was chosen. Each hemimandible was scanned 8 times with 8 different parameter combinations resulting in 160 CBCT data sets. On the cross-sectional images, six linear distances were measured. To assess the intraobserver variation, the 160 data sets were remeasured after 2 weeks. The measurement precision was calculated using Dahlberg's formula. With the same peak kilovoltage, the measurements yielded by different milliampere values were compared using the paired t-test. With the same milliampere value, the measurements yielded by different peak kilovoltage were compared using analysis of variance. A significant difference was considered when p < 0.05.

RESULTS

Measurement precision varied from 0.03 mm to 0.28 mm. No significant differences in the distances were found among the different radiographic parameter combinations.

CONCLUSIONS

Based upon the specific machine in the present study, low peak kilovoltage and milliampere value might be used for linear measurements in the posterior mandible.

Accuracy of CBCT measurements of a human skull

The purpose of this study is to assess the accuracy and reproducibility of cone-beam computed tomography (CBCT) measurements of a human dry skull by comparing them to direct digital caliper measurements. Heated gutta-percha was used to mark 13 specific distances on a human skull, and the distances were directly measured using a digital caliper and on CBCT images obtained with Iluma (3M Imtec, OK, USA) and 3D Accuitomo 170 (3D Accuitomo; J Morita Mfg. Corp., Kyoto, Japan) CBCT imaging systems. Iluma images were obtained at 120 kVp and 3.8 mA and reconstructed using voxel sizes of 0.2 and 0.3 mm(3). Accuitomo images were obtained at 60 kVp and 2 mA and a voxel size of 0.250 mm(3). In addition, 3-D reconstructions were produced from images obtained from both systems. All measurements were made independently by three trained observers and were repeated after an interval of 1 week. Agreement between observers and image type was assessed by calculating Pearson correlation coefficients, with a level of significance set at p < 0.05. Pearson correlation coefficients between readings ranged from 0.995 to 1 for all image types. Correlations among observers were also very high, ranging from 0.992 to 1 for the first reading and from 0.992 to 1 for the second reading for the different image types. All CBCT image measurements were identical and highly correlated with digital caliper measurements. Accuracy of measurements of various distances on a human skull obtained from different CBCT units and image types is comparable to that of digital caliper measurements.

Conventional multi-slice computed tomography (CT) and cone-beam CT (CBCT) for computer-assisted implant placement. Part I: relationship of radiographic gray density and implant stability

PURPOSE

The relationship of conventional multi-slice computed tomography (CT)- and cone beam CT (CBCT)-based gray density values and the primary stability parameters of implants that were placed by stereolithographic surgical guides were analyzed in this study.

MATERIALS AND METHODS

Eighteen edentulous jaws were randomly scanned by a CT (CT group) or a CBCT scanner (CBCT group) and radiographic gray density was measured from the planned implants. A total of 108 implants were placed, and primary stability parameters were measured by insertion torque value (ITV) and resonance frequency analysis (RFA). Radiographic and subjective bone quality classification (BQC) was also classified. Results were analyzed by correlation tests and multiple regressions (p < .05).

RESULTS

CBCT-based gray density values (765 ± 97.32 voxel value) outside the implants were significantly higher than those of CT-based values (668.4 ± 110 Hounsfield unit, p < .001). Significant relations were found among the gray density values outside the implants, ITV (adjusted r(2)  = 0.6142, p = .001 and adjusted r(2)  = 0.5166, p = .0021), and RFA (adjusted r(2)  = 0.5642, p = .0017 and adjusted r(2)  = 0.5423, p = .0031 for CT and CBCT groups, respectively). Data from radiographic and subjective BQC were also in agreement.

CONCLUSIONS

Similar to the gray density values of CT, that of CBCT could also be predictive for the subjective BQC and primary implant stability. Results should be confirmed on different CBCT scanners.

Evaluation of the pterygoid hamulus morphology using cone beam computed tomography

OBJECTIVE

This study consists of anatomic research of the pterygoid hamulus (PH) using 3D cone beam computed tomography (CBCT) images reconstructed from a volumetric rendering program.

STUDY DESIGN

Three hundred ninety-six sides in the CBCT scans of 198 (115 men and 83 women) patients were retrospectively analyzed. DICOM data of the patients were transferred to a surface-rendering software so as to generate 3D hard tissue surface representations of PHs. The width, length, angle, and the distance between posterior nasal spine and tip of the PH were measured. In addition, the inclinations of PHs were also evaluated in sagittal and coronal planes of the 3D images. Pearson χ(2) and Student t test were performed for statistical analysis among age, localization, and measurements (P < .05).

RESULTS

The mean PH measurements of left and right sides were 1.72 (SD 0.94) and 1.87 (SD 1.17)-mm width, and the lengths were 5.48 (AD 1.94), and 5.40 (SD 2.0) mm, respectively, with no significant difference (P > .05). All PHs were inclined toward the lateral side in the coronal plane, whereas PHs tended to incline toward the posterior rather than anterior in the sagittal plane (∼78%). The results showed no statistically significant differences among age, localization, and measurements of PHs (P > .05).

CONCLUSIONS

Knowledge about the morphology of these structures is helpful for the interpretation of imaging and provides valuable information in the differential diagnosis of untraceable pains in the oral cavity and pharynx. Because of potential problems owing to PH morphology and elongation, oral and maxillofacial radiologists should assess the radiographic images thoroughly.

Assessing the need for computed tomography for lower-third-molar extraction: a survey among 322 dentists

PURPOSE

Orthopantomograms (OPT) are used to assess the anatomical relationship between the inferior alveolar nerves (IAN) and the roots of third molars and the related risk of postextraction iatrogenic neurological lesions. When the risk is high, computed tomography (CT) or conebeam CT may be warranted. We investigated how dentists judged the need for CT from OPT to ascertain whether they comply with criteria of justification, appropriateness and optimisation in prescribing examinations involving radiation.

MATERIALS AND METHODS

A total of 2,713 letters were sent to Italian dentists (Veneto region), inviting them to access an Internet Web site showing 20 OPTs and answer a questionnaire on the need for CT or periapical X-ray. The gold standards were CT images corresponding to the OPTs. The respondents' answers were rated for appropriateness and their tendency to over- or underprescribe CT.

RESULTS

The questionnaire was completed by 11.9% of the dentists contacted. The response rate was compatible with a Web survey. Their answers generally came close to the gold standard, achieving a mean appropriateness rating of 0.636 (range 0-1). An overlap between the mandibular canal and the third-molar root was the anatomical relationship most often noted. Recommendations for CT were proportional to the number of radiographic signs indicating a risk of inferior alveolar nerve injury. Periapical X-ray was considered useful by 54.9% of dentists not recommending CT. The main reason stated for not recommending CT was that it was unnecessary for the purposes of the extraction.

CONCLUSIONS

Our survey revealed a cautious approach among the professionals interviewed, who tended to overprescribe CT.