Accuracy and precision of linear measurements in cone beam computed tomography Accuitomo tomograms obtained with different reconstruction techniques

Evaluation of the effect of autologous conditioned serum on the radiographic characteristics of hard tissue after horizontal bone augmentation in implant dentistry

Background. Bone deficiency in different areas is problematic in implant placement. Changes in histological, histomorphometric, and radiographic properties of hard tissues in the implant placement area affect many parameters of implant success. Autologous conditioned serum (ACS) is a blood product with high levels of IL1- receptor antagonists. Augmentation surgeries are required in many cases because implant placement in the edentulous areas requires a sufficient amount of bone. Therefore, this study radiographically evaluated the effect of autologous conditioned serum after horizontal bone augmentation. Methods. In this prospective RCT, 21 patients eligible patients were evaluated. The patient underwent horizontal ridge augmentation surgery in the area. The ACS-impregnated graft was in direct con-tact with the bone. The control side underwent the same surgical protocol without using ACS. Four months after surgery, a CBCT radiograph was taken, and radiographic changes in the two areas were calculated using the differences in the amount of bone formed in the horizontal dimension as well as the Hounsfield unit (HU). The data were reported using descriptive statistical methods, including means (standard deviations) and frequencies (percentages). According to the results of the Kolmog-orov-Smirnov test, the data had a normal distribution (P>0.05); therefore, paired t-test was used to compare the means of the parameters between the two groups. Results. IRadiographic examinations showed that the horizontal dimension of bone before surgery was similar between the two groups. However, after surgery in the ACS group (33.13±6.1), it was significantly higher than in the control group (62.1±86.4) (P>0.05). Also, the rate of horizontal dimension increase (the difference before and after surgery) in the ACS group was significantly higher than in the control group. Bone density before surgery was similar between the two groups. However, after surgery, there was a significant increase in the ACS group (75.56±330.42 HUs) compared to the control group (38.35±292.38 HUs) (P>0.05). Also, the rate of density increase (the difference before and after surgery) in the ACS group was significantly higher than in the control group. Conclusion. Radiographic evaluations of hard tissues showed a significant increase in the horizontal dimension of bone and density of newly formed bone using ACS compared to the control group.

Cone Beam Computed Tomography Analysis of Sphenoid Sinus Pneumatization and Relationship with Neurovascular Structures

Background

The sphenoid sinus is considered as the most variable pneumatized structure of the skull.

Purpose

The aim of the present study was to determine the prevalence of the Onodi cell as well as to evaluate the relationship between the sphenoid sinus type of pneumatization and the presence of surrounding neurovascular protrusion using cone beam computed tomography (CBCT).

Methods

The CBCT images of 500 patients/996 sides [203 males (40.6%) and 297 females (59.4%)] were analyzed in this study. The type of sphenoid sinus pneumatization, prevalence of internal carotid artery (ICA) and optic nerve (ON) protrusion and dehiscence, and also the frequency of Onodi cell were assessed.

Results

The percentages of the conchal, presellar, sellar, postsellar (a), and postsellar (b) types of pneumatization were 1%, 11.5%, 35.5%, 38.9%, and 13.1%, respectively. The more the sphenoid sinuses pneumatized, the greater the frequency of ON and ICA protrusion and dehiscence of their wall to the sinus. The prevalence of Onodi cell was 38.8%. A significant correlation was found between ON dehiscence and the presence of Onodi cells.

Conclusion

The present study demonstrated a significant relationship between the sinus type and frequency of neurovascular protrusions. Therefore, the sphenoid sinus extent of pneumatization might be useful in predicting the risk of iatrogenic damage to the surrounding structures.

Evaluation of Mandibular First Molars' Axial Inclination and Alveolar Morphology in Different Facial Patterns: A CBCT Study

Objective  The purpose of this study was to evaluate and compare the axial inclination of the mandibular first molars and their respective bone morphology among individuals with different facial patterns.

Materials and Methods  The sample comprised the cone beam computed tomographies (CBCTs) of 58 subjects divided into three groups according to the facial patterns: 18 brachyfacial (Group 1), with a mean age of 21.58 years; 23 mesofacial (Group 2), with a mean age of 19.14 years; and 17 dolichofacial subjects (Group 3), with a mean age of 19.09 years. Eight variables were evaluated on CBCT scans of each subject: buccal and lingual mandibular height, cervical and middle mandibular width, inclination of mandibular body, inclination of the mandibular molar buccal surface, molar width, molar angulation and tooth/bone angle. Intergroup comparisons were performed with one-way analysis of variance followed by Tukey tests.

Results  Buccal mandibular height presented statistically significant difference in the three facial patterns. Lingual mandibular height and mandibular inclination showed to be statistically and significantly smaller in brachyfacial subjects than in the other two groups. Mandibular width presented a statistically significant difference between brachyfacial and mesofacial groups. Negative correlations could be observed between the facial pattern and the buccal and lingual mandibular heights and inclination of the mandibular body.

Conclusion  Buccal mandibular height was significantly and progressively larger in brachyfacial, mesofacial, and dolichofacial subjects. Lingual mandibular height was significantly smaller in brachyfacial than in mesofacial and dolichofacial subjects. Mandibular width was significantly thicker in brachyfacial than in mesofacial subjects. Brachyfacial subjects had smaller mandibular inclination than mesofacial and dolichofacial subjects.

Accuracy of cone beam computed tomography in measuring thicknesses of hard-tissue-mimicking material adjacent to different implant thread surfaces

Background/purpose

To evaluate the measurement accuracy of hard-tissue thicknesses adjacent to dental implants with different thread designs on images obtained from cone beam computed tomography (CBCT) using an in vitro model.

Materials and methods

On 4 × 13-mm implant, the neck of the implant was designed with micro-threads, and the apical part was covered by macro-threads; these implants were placed in a vinyl polysiloxane block that mimicked hard-tissue. Models were prepared with various thicknesses of 2.0, 1.0, 0.5 and 0.3 mm adjacent to the dental implant. Each model was scanned using CBCT, and the thickness of the cortical bone from the outer surface of the micro-threads and macro-threads were recorded. Ground sections were prepared, and the thickness was measured with electronic calipers as the gold standard (GS) measurement.

Results

CBCT measurements of the micro-thread surface were consistently underestimated compared to the GS measurement when the thickness of the hard-tissue-mimicking material was ≤1.0 mm. In comparison, CBCT measurements of the macro-thread surface closely approximated the standard measurement, except when the thickness of the hard-tissue-mimicking material was 0.3 mm. The mean percentage errors from the standard measurement for the 2.0-, 1.0-, 0.5-, and 0.3-mm thickness groups were 4.8%, 16.4%, 37.8%, and 92.6%, respectively, for the micro-thread group, and were 0.6%, 2.9%, 9.5%, and 40.8%, respectively, for the macro-thread group.

Conclusion

Within the limitations of this study, we conclude that CBCT may not produce sufficient resolution for thin sections of hard tissue-mimicking materials adjacent to micro-thread surfaces.

The OpenEar library of 3D models of the human temporal bone based on computed tomography and micro-slicing

Virtual reality surgical simulation of temporal bone surgery requires digitized models of the full anatomical region in high quality and colour information to allow realistic texturization. Existing datasets which are usually based on microCT imaging are unable to fulfil these requirements as per the limited specimen size, and lack of colour information. The OpenEar Dataset provides a library consisting of eight three-dimensional models of the human temporal bone to enable surgical training including colour data. Each dataset is based on a combination of multimodal imaging including Cone Beam Computed Tomography (CBCT) and micro-slicing. 3D reconstruction of micro-slicing images and subsequent registration to CBCT images allowed for relatively efficient multimodal segmentation of inner ear compartments, middle ear bones, tympanic membrane, relevant nerve structures, blood vessels and the temporal bone. Raw data from the experiment as well as voxel data and triangulated models from the segmentation are provided in full for use in surgical simulators or any other application which relies on high quality models of the human temporal bone.

Comparison of the accuracy of full head cone beam CT images obtained using a large field of view and stitched images

OBJECTIVE:

The aim of this study was to investigate the accuracy of the new stitching feature of the Morita 3D Accuitomo device by comparing it with the I-CAT device and real measurements.

METHODS:

Eight dry skulls were used in this study. The full scan mode of an I-CAT device and the new stitching feature of the Morita 3D Accuitomo device were used to obtain full head cone beam CT (CBCT) images, and the linear distances between the selected anatomical sites were measured by two observers. The real distances were measured directly on the skulls using digital calipers. Statistical analyses were performed using the intraclass correlation coefficient and Bland-Altman Limits of Agreement.

RESULTS:

High or perfect agreement was detected between the CBCT images and real measurements. The Bland-Altman Limits of Agreement analysis revealed that the stitched coronal and sagittal images of the Morita might differ by >1.54-1.67 or <0.01 mm from the real measurements.

CONCLUSIONS:

The stitched images of the Morita CBCT device showed perfect agreement with both real measurements and the images of an I-CAT full head scan. After the evaluation of the radiation doses received from stitching sectional images, this device may be used to obtain full head images.

Accuracy of linear measurements performed with two imaging software in cone-beam computed tomography scans of dry human mandibles

The present study aimed to assess the accuracy of linear measurements performed with two software packages in multislice (MSCT) and cone beam (CBCT) computed tomography (CT) images. The sample consisted of 10 human mandibles marked standardly 8 times with metallic orthodontic wires. The mandibles underwent both MSCT and CBCT scanning and were measured linearly and digitally with two software packages, namely Studio 3.1® (Anne Solutions®, SP, Brazil) (ST) and Implant Viewer 2.817® (Anne Solutions®, SP, Brazil) (IV). The linear measurements were the mandibular height (MH) and width (MW), and the distance from the alveolar ridge to the mandibular canal (AC). To validate the measurements, the mandibles were sectioned in the marked regions and measured with a digital caliper. Statistically significant differences were not observed between the measurements (MH, MW, and AC) taken digitally with the two software packages from images obtained from the two scanning modalities (MSCT and CBCT) and the measurements taken manually with a digital caliper (p>0.05). MSCT and CBCT images measured digitally with ST and IV software packages resulted in reliable outcomes when compared to measurements obtained manually. Both software and imaging modalities are reliably useful for planning surgical procedure in the dental practice.

Dental implant navigation system guide the surgery future

No study has investigated the effect of learning curves on the accuracy of dental implant navigation systems. This study evaluated the accuracy of the dental implant navigation system and established the learning curve according to operation site and operating time. Each dental model was used for drilling 3 missing tooth positions, and a patient tracking module was created. The same dentist performed the drilling test for 5 sets of dental models. CT back scanning was performed on the dental models. Customized implants based on the drilled holes were inserted. The relative error between the preoperative planning and actual implant was calculated. Using the dental navigation system could help dentists position implants more accurately. Increasing the frequency with which a dentist used the navigation system resulted in shorter operations. Longitudinal and angular deviation were significantly (P < 0.0001 and P = 0.0164). We found that the same level of accuracy could be obtained for the maxilla and mandible implants. The Student's t test demonstrated that the longitudinal error, but not the total or angular error, differed significantly (P = 0.0012). The learning curve for the dental implant navigation system exhibited a learning plateau after 5 tests. The current system exhibited similar accuracy for both maxillary and mandibular dental implants in different dental locations. The one-way ANOVA revealed that the total, longitudinal, and angular errors differed significantly (P < 0.0001, P < 0.0001 and P = 0.0153). In addition, it possesses high potential for future use in dental implant surgery and its learning curve can serve as a reference for dentists.

A comparative study of cone beam computed tomography and conventional radiography in diagnosing the extent of root resorptions

Background

Root resorptions are assessed and diagnosed using different radiographical techniques. A comparison of the ability to assess resorptions on two-dimensional (2D) and three-dimensional (3D) radiographs is, hitherto, lacking. The aims of this study were to evaluate the accuracy of 2D (periapical radiographs, PA and panoramic radiograph, PAN) and 3D (cone beam computed tomography, CBCT) radiographic techniques in measuring slanted root resorptions compared to the true resorptions, a histological gold standard, in addition to a comparison of all the radiographic techniques to each other.

Methods

Radiographs (CBCT, PA, and PAN), in addition to histological sections, of extracted deciduous canines from thirty-four patients were analyzed. Linear measurements of the most and least resorbed side of the root, i.e., “slanted” resorptions, were measured using an analyzing software (Facad ®). For classification of slanted root resorptions, a modified Malmgren index was used.

Results

PAN underestimated the root length on both the least and most resorbed side. Small resorptions, i.e., low modified Malmgren scores, were more difficult to record and were only assessed accurately using CBCT. The root resorption scores were underestimated using PA and PAN. In assessment of linear measures, PAN differed significantly from both CBCT and PA.

Conclusions

CBCT is the most accurate technique when measuring and scoring slanted root resorptions.

Effect of Head Position on Maxillofacial Transverse Measurements Made on the Skull and Cone Beam Computed Tomography Scans

Article Incorrect patient positioning and the resultant image distortion occur in many radiographic examinations. This study aimed to assess the effect of tilting, rotation and tipping of the head on the accuracy of maxillofacial transverse measurements made on cone beam computed tomography (CBCT) scans. The CBCT scans were obtained in central position of 10 dry human skulls. Using three-dimensional (3D) Dolphin software, six positions namely 10° and 20° tilts, rotations and tips were reconstructed of central position. Transverse distances between landmarks were measured on 3D scans and the skulls. The intraclass correlation coefficient (ICC) and the Bland-Altman plot were used to compare the mean values measured by the two observers. For most landmarks, no significant differences were noted between the mean transverse distances measured in the six positions and those measured in central position on 3D scans (p>0.005). In conclusion, all measurements of transverse distances made on 3D scans in different positions were underestimated compared to the actual values measured on the skull.

Anatomic Investigation of Commonly Used Landmarks for Evaluating Rotation During Forearm Fracture Reduction

BACKGROUND

Evaluating rotation during open reduction and internal fixation of a forearm fracture is of paramount importance. In challenging cases, surgeons may utilize radiographic relationships between proximal and distal radial and ulnar landmarks to assess rotational position. However, to our knowledge, limited anatomic data are available to confirm these relationships.

METHODS

Six hundred cadaveric radii and ulnae were obtained. Digital representations of the bicipital tuberosity, the radial styloid, the coronoid process, and the ulnar styloid were acquired, and the rotational profiles between respective landmarks were calculated. In order to validate the results and investigate the ability to differentiate rotated osseous positions, each bone was imaged in increments of 10° of rotation and the profile of each landmark was measured.

RESULTS

The radial styloid was at a mean of 158° ± 14° of supination relative to the bicipital tuberosity. The ulnar styloid was at a mean of 185° ± 14° of supination relative to the coronoid process. Imaging of the bones in increments of 10° of rotation supported the relationships above. It was also found that a 1-mm difference in profile size corresponded to up to 60° of rotation for the average ulna, compared with 10° for the average radius.

CONCLUSIONS

Our findings suggest that using the bicipital tuberosity and the radial styloid to assess intraoperative rotation of the radius on anteroposterior radiographs may be of limited value; the landmarks were not generally 180° apart. Although the rotational positions of the coronoid process and the ulnar styloid were, on average, closer to 180°, surgeons should be aware of the wide range of normal anatomy as well as the inability to judge rotation by as much as 60°, even for an "ideal" ulna.

CLINICAL RELEVANCE

This study, to our knowledge, represents the first anatomic investigation of the rotational profiles between the osseous landmarks used to assess forearm rotation after fracture. We recommend that surgeons first image the bicipital tuberosity at its largest profile, supinate the arm 20°, and confirm that the radial styloid is at its largest profile. The ulna can then be assessed to support the lack of rotational deformity in the forearm.

Is there a consensus for CBCT use in Orthodontics?

This article aims to discuss current evidence and recommendations for cone-beam computed tomography (CBCT) in Orthodontics. In comparison to conventional radiograph, CBCT has higher radiation doses and, for this reason, is not a standard method of diagnosis in Orthodontics. Routine use of CBCT in substitution to conventional radiograph is considered an unaccepted practice. CBCT should be indicated with criteria only after clinical examination has been performed and when the benefits for diagnosis and treatment planning exceed the risks of a greater radiation dose. It should be requested only when there is a potential to provide new information not demonstrated by conventional scans, when it modifies treatment plan or favors treatment execution. The most frequent indication of CBCT in Orthodontics, with some evidence on its clinical efficacy, includes retained/impacted permanent teeth; severe craniofacial anomalies; severe facial discrepancies with indication of orthodontic-surgical treatment; and bone irregularities or malformation of TMJ accompanied by signs and symptoms. In exceptional cases of adult patients when critical tooth movement are planned in regions with deficient buccolingual thickness of the alveolar ridge, CBCT can be indicated provided that there is a perspective of changes in orthodontic treatment planning.

Classification of periodontal biotypes with the use of CBCT. A cross-sectional study

OBJECTIVES

The aim of this study is to investigate the relationship between periodontal morphometric parameters and to develop a biotype classification based on the variables examined with the use of cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

Forty-two periodontally healthy subjects that underwent a CBCT examination as part of a different diagnostic procedure participated in the study. Measurements were performed on sectional images and included gingival thickness and labial bone plate thickness midbuccally, crown width to crown length ratio, bone crest to the CEJ distance and bone crest to the gingival margin distance midbuccally, and at the approximal aspects of 186 maxillary anterior teeth.

RESULTS

Gingival thickness at the level of CEJ was positively correlated with labial bone plate thickness and crown form. Crown form was not correlated with labial bone plate thickness. Cluster analysis supported the existence of four periodontal biotypes, "thin," "thick," "average," and "mixed." Labial bone plate thickness was thinner than 1 mm at 70 % of the measured sites.

CONCLUSIONS

Only 50 % of the teeth belonged to thin or thick biotype. The other 50 % of the teeth belonged to the average cluster or presented mixed characteristics. Assessment of labial bone plate thickness based on periodontal biotype should be made with caution.

CLINICAL RELEVANCE

Taking into consideration the characteristics of periodontal biotypes enables the clinician to avoid complications in periodontology, prosthetic dentistry, implant dentistry in the esthetic zone, and orthodontics.

Influence of Head Orientation in Linear Measurement for Implant Planning in Cone Beam Computed Tomography

AIM

Use of dental implants in edentulous patients has become a common treatment modality. Treatment of such implants requires radiographic evaluation, and in most cases several different imaging techniques are necessary in order to evaluate the height, width and the structure of bone at implant site. The aim of this study was to evaluate the influence of head orientation in linear measurement for implant planning in cone beam computed tomography (CBCT).

MATERIALS AND METHODS

In the present in vitro study, 11 human dry mandibles were used. The width and height of bone at the central, canine and molar teeth areas were measured on the left and right sides by using digital calipers (as gold standard) and on CBCT images with Reaxis option and no Reaxis. Data were analyzed with Statistical package for the social sciences (SPSS) 18, using pair t-test, Tukey test and intraclass correlation (ICC).

RESULTS

Data were collected by evaluation of 11 skulls and 66 samples on the whole. There were no significant differences in bone width in any area in both Reaxis and no Reaxis option (p > 0.05). There were significant differences in bone height in the central (p = 0.005) and molar teeth areas (p = 0.010). The results did not show any significant differences between the observers (p = 0.329).

CONCLUSION

Using the Reaxis option does not affect the measurement of bone width, while use of this option can make a significant difference for height measurements.

[Maxillary canine impaction increases root resorption risk of adjacent teeth: A problem of physical proximity]

INTRODUCTION

Our objectives were to investigate the prevalence, resorption location and extent, and potential risk factors for impacted canine-associated root resorption (ICARR) in Chinese patients, who, unlike white patients, have predominantly buccal maxillary canine impactions.

METHODS

Pretreatment cone-beam computed tomography scans of 170 Chinese subjects (ages, 12-30 years; mean, 14.5 years) with impacted maxillary canines (101 buccal and 69 palatal impactions) and 170 age- and sex-matched subjects without impactions were used. All cone-beam computed tomography records were evaluated in software programs by 1 rater. The prevalence, location, and extent of ICARR at the maxillary lateral incisor, central incisor, and first premolar were analyzed. To identify risk factors for ICARR, the subjects with impacted canine were divided into 2 groups (with and without root resorption). Measurements of 10 variables were individually compared between the groups and then tested together by using binary logistic regressions for each tooth.

RESULTS

Compared with the control subjects and the side of nonimpaction, root resorption was significantly more prevalent in the canine-impaction subjects and the side of impaction (P\0.01), with overall prevalence rates of 27%, 18% and 10% at the maxillary lateral incisor, the central incisor, and the first premolar, respectively. Predominantly affecting the apical third of all teeth, ICARR, if present, reached the pulp of the maxillary lateral incisor, the central incisor, and the first premolar at rates of 36%, 57%, and 0%, respectively. Individually, variables reflecting the proximity to the impacted maxillary canine had different measurements (P\0.05) between the impaction sites (maxillary quadrants) with and without root resorption for each tooth, whereas the canine development stage factor was only significant for the maxillary central and lateral incisors. No significant difference of ICARR prevalence was found between subjects with buccal and palatal impactions. Combined, the contact relationship was the dominant predictor for ICARR at all teeth, with "in contact" (\1 mm separation) having the largest and most significant increase of root resorption likelihood compared with "out of contact" ($1 mm separation); odds ratios were 9.9, 3.7 and 5.9 for the maxillary lateral incisor, the central incisor, and the first premolar, respectively.

CONCLUSIONS

Maxillary canine impaction increases the risk of root resorption at adjacent teeth (incisors and first premolars). Physical proximity (\1 mm) between the impacted canine and an adjacent root is the most important predictor for root resorption, and this characteristic is largely similar in Chinese patients to that in white people.

Linear accuracy and reliability of volume data sets acquired by two CBCT-devices and an MSCT using virtual models: a comparative in-vitro study

OBJECTIVE

To discriminate clinically relevant aberrance, the accuracy of linear measurements in three-dimensional (3D) reconstructed datasets was investigated.

MATERIALS AND METHODS

Three partly edentulous human skulls were examined. Landmarks were defined prior to acquisition. Two CBCT-scanners and a Quad-slice CT-scanner were used. Actual distances were physically measured with calipers and defined as a reference. Subsequently, from digital DICOM datasets, 3D virtual models were generated using maximum intensity projections (MIPs). Linear measurements were performed by semi-automated image analysis. Virtual and analogue linear measurements were compared using repeated measurements in a mixed model (p ≤ 0.05).

RESULTS

No significant difference was found among all of the digital measurements when compared to one another, whereas a significant difference was found in matched-pairs analysis between CBCT and calipers (p = 0.032). All digitally acquired data resulted in lower mean values compared to the measurements via calipers. A high level of inter-observer reliability was obtained in the digital measurements (inter-rater correlation = 0.988-0.993).

CONCLUSIONS

The reconstructed datasets led to highly consistent values among linear measurements. Yielding sub-millimeter precision, these modalities are assumed to reflect reality in a clinically irrelevant altered manner. During data acquisition and evaluation, a maximum of precision must be achieved.

Alveolar bone loss and ageing: possible association with coronary heart diseases and/or severe vascular diseases

OBJECTIVE

The objective of this study was to utilise a new methodological approach based on radiographic examinations to demonstrate a potential association between coronary heart diseases (CHD) as well as severe hypertension and alveolar bone loss (ABL) in older adults.

BACKGROUND

Many studies, primarily assessing clinical parameters, underline the association between periodontal diseases and cardiovascular diseases. The relationship between ABL and CHD/vascular diseases (VD) is potentially of high importance because of their prevalence in populations, and they represent an important issue in the fields of epidemiology and public health. Therefore, this topic was approached with new tools.

MATERIALS AND METHODS

The study was comprised of 236 participants over 50 years. A clinical examination and a radiographic assessment of ABL were performed. Direct measures of alveolar bone level were recorded using CT scans, and different variables were studied (age, sex, Plaque index, cigarettes per day, coronary heart disease and vascular disease status). A medical examination report was attached to the investigation file.

RESULTS

The results confirmed a positive association between CHD/VD and periodontal destruction; alveolar bone destruction represented a risk factor for CHD/VD [odds ratio (OR): 1.27; 95% CI: 1.01-1.60; p < 0.037].

CONCLUSION

This study supports an association between periodontal diseases and CHD/VD independent of known confounders, although an aetiological link of causality has not been established.

Vertical measurements for planning palatal mini-implants in lateral radiography and cone beam computed tomography

OBJECTIVE

To compare palatal bone height measurements in the region of first premolars for planning palatal mini-implant insertion on conventional lateral radiography (CLR), cone beam computed tomography (CBCT), and reformatted virtual lateral radiography (VLR).

MATERIALS AND METHODS

One hundred ten images of CLR, VLR, and CBCT from the same patient were used. Linear measurements corresponding to the relevant dimension of available bone on upper first premolar site were performed between the hard palate floor and the nasal floor. The Friedman test compared the measurements of all imaging modalities. Intraobserver and interobserver agreement was calculated with the intraclass correlation coefficient (ICC).

RESULTS

The ICC values showed excellent intraobserver and interobserver agreement. VLR examination resulted in measurements statistically different from both CBCT and CLR images (P < 0.05), being underestimated when compared with these techniques, and the values found on CLR did not show statistically significant differences from the CBCT images (P > 0.05).

CONCLUSIONS

The measurements for planning palatal mini-implants at the level of first premolars are comparable on CLR and multiplanar reconstructions of CBCT, whereas underestimated in reformatted examinations (VLR).

Development and implementation of a low-cost phantom for quality control in cone beam computed tomography

A phantom for quality control in cone beam computed tomography (CBCT) scanners was designed and constructed, and a methodology for testing was developed. The phantom had a polymethyl methacrylate structure filled with water and plastic objects that allowed the assessment of parameters related to quality control. The phantom allowed the evaluation of essential parameters in CBCT as well as the evaluation of linear and angular dimensions. The plastics used in the phantom were chosen so that their density and linear attenuation coefficient were similar to those of human facial structures. Three types of CBCT equipment, with two different technological concepts, were evaluated. The results of the assessment of the accuracy of linear and angular dimensions agreed with the existing standards. However, other parameters such as computed tomography number accuracy, uniformity and high-contrast detail did not meet the tolerances established in current regulations or the manufacturer's specifications. The results demonstrate the importance of establishing specific protocols and phantoms, which meet the specificities of CBCT. The practicality of implementation, the quality control test results for the proposed phantom and the consistency of the results using different equipment demonstrate its adequacy.

Cone-beam computed tomography for assessment of palatal displaced canine position: a methodological study

OBJECTIVE

To assess the inter- and intraexaminer reliability of a measurement method for evaluation of eruption angles and position of palatal displaced canines (PDCs) with cone-beam computed tomography (CBCT) images and to test the validity of the measured angles on a dry skull.

MATERIALS AND METHODS

Twenty patients (eight boys, 12 girls; age 11.4±1.2 years) were randomly chosen among 67 patients from a study evaluating the interceptive effect of extracting the deciduous canine in children with PDCs. In total, 60 images were analyzed, because each patient had three CBCT examinations (baseline, 6-month control, and endpoint). Two observers assessed the following measurements twice: mesioangular and sagittal angle, vertical position, canine cusp tip, and canine apex to dental arch. The validity of the angular measurements was tested against angular measurements on a dry skull using mathematical formulations.

RESULTS

The inter- and intraexaminer mean differences for angular and linear measurements were all low and statistically insignificant (P>.05). The mean differences between the physical and 3D measurements were 0.5±0.39 mm for the sagittal angle and 0.22±0.19 mm for the mesioangular angle.

CONCLUSIONS

Linear and angular measurements on CBCT images are accurate and precise and can be used to assess the precise position of a PDC.

Curvature analysis of femoral shaft in total knee arthroplasty patient and control group

For some patients with joint illnesses such as rheumarthritis or varus deformity, the total knee arthroplasty (TKA) procedures are performed. However, when inserting metal cutting guide for the procedures, due to the femoral shaft bowing, complications such as the cortex of the femoral shaft damages or secondary fractures can be caused. If the central coordinate value of the femoral shaft is known, the metal cutting guide could be inserted into the anatomical center, so such complications can be prevented. In this study, CT images of femoral shafts of 10 individuals in the experiment group who are in need of receiving the total knee arthroplasty procedures and those of 10 individuals in the control group without illness in the femoral shaft have been utilized to locate the 3-dimensional coordinate values. Then, Matlab was utilized to identify the central coordinate value in order to obtain a graph reflecting the anatomical shapes as well as to acquire the 3-dimensional curvature values by section. As a result, the average curvature range of femoral shafts of the experiment group was determined to be 631.2 mm whereas the average curvature range of femoral shafts of the control group was determined to be 1430.4 mm. The statistical significant of the measured results was verified through ANOVA analysis. Based on these results, it was verified that the level of curvature of the femoral shaft of the experiment group was higher. If the anatomical central points are located and analyzed using this methodology, it would be helpful in performing orthopedic operations such as the total knee arthroplasty.

Maxillary canine impaction increases root resorption risk of adjacent teeth: a problem of physical proximity

INTRODUCTION

Our objectives were to investigate the prevalence, resorption location and extent, and potential risk factors for impacted canine-associated root resorption (ICARR) in Chinese patients, who, unlike white patients, have predominantly buccal maxillary canine impactions.

METHODS

Pretreatment cone-beam computed tomography scans of 170 Chinese subjects (ages, 12-30 years; mean, 14.5 years) with impacted maxillary canines (101 buccal and 69 palatal impactions) and 170 age- and sex-matched subjects without impactions were used. All cone-beam computed tomography records were evaluated in software programs by 1 rater. The prevalence, location, and extent of ICARR at the maxillary lateral incisor, central incisor, and first premolar were analyzed. To identify risk factors for ICARR, the subjects with impacted canine were divided into 2 groups (with and without root resorption). Measurements of 10 variables were individually compared between the groups and then tested together by using binary logistic regressions for each tooth.

RESULTS

Compared with the control subjects and the side of nonimpaction, root resorption was significantly more prevalent in the canine-impaction subjects and the side of impaction (P <0.01), with overall prevalence rates of 27%,18%, and 10% at the maxillary lateral incisor, the central incisor, and the first premolar, respectively. Predominantly affecting the apical third of all teeth, ICARR, if present, reached the pulp of the maxillary lateral incisor, the central incisor, and the first premolar at rates of 36%, 57%, and 0%, respectively. Individually, variables reflecting the proximity to the impacted maxillary canine had different measurements (P <0.05) between the impaction sites (maxillary quadrants) with and without root resorption for each tooth, whereas the canine development stage factor was only significant for the maxillary central and lateral incisors. No significant difference of ICARR prevalence was found between subjects with buccal and palatal impactions. Combined, the contact relationship was the dominant predictor for ICARR at all teeth, with "in contact" (<1 mm separation) having the largest and most significant increase of root resorption likelihood compared with "out of contact" (≥1 mm separation); odds ratios were 9.9, 3.7, and 5.9 for the maxillary lateral incisor, the central incisor, and the first premolar, respectively.

CONCLUSIONS

Maxillary canine impaction increases the risk of root resorption at adjacent teeth (incisors and first premolars). Physical proximity (<1 mm) between the impacted canine and an adjacent root is the most important predictor for root resorption, and this characteristic is largely similar in Chinese patients to that in white people.

Radiation dose and accuracy analysis of newly developed cone-beam CT for dental and maxillofacial imaging

Cone-beam computed tomography (CBCT) has become increasingly popular in dental and maxillofacial imaging due to its accurate 3D information, minimal radiation dose, and low machine cost. In this paper, we have proposed the newly developed CBCT scanner, called DentiiScan. Our gantry system consisting of a cone-beam X-ray source and an amorphous silicon flat panel detector is rotated around a patient's head. With the large area detector, only a single rotation is needed to reconstruct the field-of-view area from chin to eyes and our reconstructed algorithm based on GPU calculation is about 30 times faster than the CPU-based algorithm. The radiation dose was measured and compared to other dental and medical CT machines. The absorbed radiation dose from our proposed CBCT machine is significantly low. In addition, geometric accuracy was analyzed when the test object was scanned at the normal position as well as the inclined position. The results from three observers repeated for five times confirm that the machine can produce reconstructed images with high accuracy.

Accuracy of peri-implant bone thickness and validity of assessing bone augmentation material using cone beam computed tomography

OBJECTIVES

The aim of this study was to evaluate the accuracy of measuring bone thickness surrounding dental implants and the reliability of assessing existence and completion of osseous integration of augmentation material using a cone beam computed tomography (CBCT) system.

MATERIALS AND METHODS

In jaws of foxhounds, artificial defects were regenerated by guided bone regeneration and then dental implants were placed. After putting down the dogs, the jaws were separated from the bodies and exposed in a CBCT system. The bone thickness was measured on both buccal and oral sides of the implants at different levels. Every examiner evaluated existence and integration of bone augmentation materials (BAM) and the completeness of marginal implant covering. The same measurements and evaluations were performed at digital images of the corresponding histological sections.

RESULTS

The mean and the standard deviation of the differences between radiological and histological measurements of peri-implant bone thickness were -0.22 mm and 0.77 mm, respectively. Sensitivity and specificity were 0.77 and 0.60 for existence of BAM, 0.59 and 0.74 for completed integration, and 0.39 and 0.71 for full covering of the implant surface.

CONCLUSIONS

The present study indicates that the PaX Duo3D(®) CBCT system allows measurements of peri-implant bone thickness at an accuracy of half a millimeter, and--within limits--assessing the existence and integration of BAM. It is not possible to evaluate whether the implant is covered completely by hard tissue.

CLINICAL RELEVANCE

Peri-implant bone thickness is a key factor for obtaining initial implant stability. The accuracy of its measurement has clinical impact. Radiological assessment of existence and integration of BAM would be of great benefit to the evaluation of augmentation procedures.

Accuracy of linear measurements of galileos cone beam computed tomography in normal and different head positions

Introduction. The aim of this study was to determine the accuracy of linear measurements in dry human skulls in ideal position and different deviated positions of the skull. Methods. 6 dry human skulls were included in the study. Opaque markers were attached to alveolar bone. Buccolingual and mesiodistal distances and heights were measured in 5 different regions of either jaws using a digital caliper. Radiographic distances were measured in ideal, rotation, tilt, flexion, and extension positions of the skulls. The physical and radiographic measurements were compared to estimate linear measurement accuracy. Results. The mean difference between physical measurements and radiographic measurements was 0.05 ± 0.45. There was a significant difference between physical measurements and radiographic measurements in ideal, rotation, tilt, and extension positions (P   value < 0.05). Conclusions. The accuracy of measurements in GALILEOUS CBCT machine varies when the position of the skull deviates from ideal; however, the differences are not clinically significant.

Measurement accuracy of temporomandibular joint space in Promax 3-dimensional cone-beam computerized tomography images

OBJECTIVE

The aim of this study was to evaluate and compare the measurement accuracy of the temporomandibular joint (TMJ) space in the Promax 3D cone-beam computerized tomography (CBCT) images scanned with 2 different dental protocols.

STUDY DESIGN

TMJ space impression models were made according to the occlusion. Forty joints were scanned with the standard and the large view protocol of the Promax 3D CBCT scanner. Two observers measured the joint spaces 3 times on both radiographs and the photocopies of the impression models.

RESULTS

A total of 120 CBCT images were measured. There were no significant differences among the actual joint spaces and the CBCT measurements performed with the 2 scanning protocols (P = .305). The inter- and intraobserver variabilities were not significant.

CONCLUSIONS

The 2 scanning protocols provided by the Promax 3D CBCT scanner were reliable and similar for recording the TMJ space.

Accuracy of bone surface size and cortical layer thickness measurements using cone beam computerized tomography

OBJECTIVES

The purpose of this study was to determine the accuracy of Cone Beam Computerized Tomography (CBCT) reconstructions in displaying bone surface size and cortical layer thickness.

MATERIALS AND METHODS

Two fresh frozen cadaver heads were scanned using a CBCT (i-CAT(™) 3D Imaging System; Imaging Sciences International Inc.). The mandibles were sectioned and digitalized for histological evaluation. Dimensions as measured on these sections were compared with CBCT measurements of the same region with the use of 3D image-based planning software (Procera System NobelGuide(™); Nobel Biocare). To allow optimal comparison between histological and CBCT sections, reference markers were placed into the mandibles. The Student t-test was utilized to analyze the data. Differences with P-values <0.05 were considered significant.

RESULTS

The total height and width of the mandibular body, as measured on CBCT views, were larger compared with the histological values with a maximum difference of 0.33 mm (SD ± 0.34). Cortical thickness measurements were significantly thicker on CBCT sections (P < 0.006) with absolute differences ranging up to ±0.63 mm (SD ±0.28) and relative differences ranging up to 82.6%.

CONCLUSION

CBCT images (i-CAT 3D Imaging System), viewed on the planning software Procera System NobelGuide, tend to overestimate the anatomical truth in assessing both bone height and width; especially cortical thicknesses are depicted thicker than in reality. When using CBCT images for presurgical assessment, one should be aware of this phenomenon of exaggeration of dimensions.

Analysis of pneumatization and neurovascular structures of the sphenoid sinus using cone-beam tomography (CBT)

BACKGROUND

The sphenoid sinus is a frequent target of paranasal sinus surgery. Because of the high risk of injuring the surrounding structures (e.g. internal carotid artery, optical nerve) a preoperative imaging is absolutely necessary.

PURPOSE

To analyze the possibilities of cone-beam computed tomography (CBCT), which is especially quite a new technique in ENT, in the evaluation of the sphenoid sinus, its surrounding structures, and the corresponding anatomical variations.

MATERIAL AND METHODS

This was a retrospective, single-centre study of 580 patients (1160 sides = cases). The Accu-I-Tomo-F17 was used. Pneumatization of sphenoid sinus, course of internal artery, course of optical nerve, and dehiscence of the bony canals were evaluated.

RESULTS

In the case of pneumatization a type I (completely missing or minimal sphenoid sinus) was found in two patients (0.3%), type II (posterior wall of sphenoid sinus is in front of the anterior wall of the sella) in 38 patients (6.6%), type III (posterior wall is between anterior and posterior wall of sella) in 332 patients (57,2%), type IVa (posterior wall is behind the posterior wall of sella without air dorsal the sella) in 104 patients (17.9%), and type IVb (similar to type IVa but with air dorsal the sella) in 104 patients (17.9%). In 1025 cases (89.5%) a smooth course of the internal carotid artery was found whereas a free course could be detected in 120 cases (10.5%). Defects of the bony canal of the optical nerve were found in 16.7% and of the internal carotid artery in 2.7% of the cases. The optical nerve showed a free course through the sphenoid in 151 cases (13.7%) and a smooth course in 1007 cases (87.0%).

CONCLUSION

CBCT could evaluate all relevant anatomic structures and answer the questions of different anatomical variants. A modified classification of the pneumatization of the sphenoid sinus could be described. Frequencies of anatomical variations are in accordance with the current literature of CT research.

Accuracy assessment of the axial images obtained from cone beam computed tomography

OBJECTIVE

The aim of this study was to evaluate accuracy of linear measurements assessed from axial tomograms and the influence of the use of different protocols in two cone beam CT (CBCT) units.

METHODS

A cylinder object consisting of Nylon® (Day Brazil, Sao Paulo, Brazil) with radiopaque markers was radiographically examined applying different protocols from NewTom 3G(TM) (Quantitative Radiology s.r.l, Verona, Veneto, Italy) and i-CAT(TM) (Imaging Sciences International, Hatfield, PA) units. Horizontal (A-B) and vertical (C-D) distances were assessed from axial tomograms and measured using a digital calliper that provided the gold standard for actual values.

RESULTS

There were differences when considering acquisition protocols to each CBCT unit. Concerning all analysed protocols from i-CAT(TM) and Newtom 3G(TM), both A-B and C-D distances presented underestimated values. Measurements of the axial images obtained from NewTom 3G(TM) (6 inch 0.16 mm and 9 inch 0.25 mm) were similar to the ones obtained from i-CAT(TM) (13 cm 20 s 0.3 mm, 13 cm 20 s 0.4 mm and 13 cm 40 s 0.25 mm).

CONCLUSION

The use of different protocols from CBCT machines influences linear measurements assessed from axial images. Linear distances were underestimated in both equipments. Our findings suggest that the best protocol for the i-CAT(TM) is 13 cm 20 s 0.3 mm and for the NewTom 3G(TM), the use of 6 inch or 9 inch is recommended.

Reliability and reproducibility of linear mandible measurements with the use of a cone-beam computed tomography and two object inclinations

OBJECTIVE

The aim of this study was to assess the influence of inclination of the object on the reliability and reproducibility of linear measurements of anatomic structures of the mandible on images obtained using cone-beam CT (CBCT).

METHODS

Ten linear dimensions between anatomical landmarks were measured in a dry mandible. The measurements were performed with a manual calliper three times by three observers. The mandible was scanned with Planmeca Promax 3D cone-beam CT (Planmeca Oy, Helsinki, Finland) with the base of the mandible parallel as well as tilted 45° to the horizontal plane. Computer measurements of the linear dimension were performed by three observers. The radiographic measurements were performed four times for each experimental setting. A total of 240 measurements were performed. Reproducibility was evaluated through comparison of standard deviation (SD) and estimation of intraclass correlation coefficient (ICC). The error was estimated as the absolute difference between the radiographic measurements and the mean manual calliper measurements.

RESULTS

The mean SD for the radiographic measurements was 0.36 mm for the horizontally positioned mandible and 0.48 mm for the inclined mandible. The ICC between examiners was 0.996 mm, between sessions was 0.990 mm and between CBCT measurements and calliper was 0.992 mm. The overall absolute mean measurement error was 0.40 mm (SD 0.39 mm). The percentage of errors that exceeded 1 mm was 6.7%.

CONCLUSION

The results revealed high reliability of measurements performed on CBCT images independently from object position, examiner's experience and high reproducibility in repeated measurements settings.

Analysis of the fossa olfactoria using cone beam tomography (CBT)

CONCLUSION

A cone beam tomography (CBT) examination of the olfactory area with its different variants allows development of an individual anatomical-radiological risk profile of the ethmoid and the identification of so-called 'dangerous ethmoids.'

OBJECTIVE

Preoperative imaging performed with high-resolution CBT is imperative for analysis of the risk of injuring the olfactory fossa during sinus surgery. This study aimed to analyze the relevant parameters.

METHODS

This was a retrospective, single-center study of 141 patients. The Accu-I-Tomo F17 was used. Keros type, the point of the anterior ethmoid artery, and the angle between the lateral lamella and the cribriform plate (α(lc)) were evaluated.

RESULTS

The Keros types were distributed as follows: type I, 13% (α(lc): 131°); type II, 64% (α(lc): 116°); type III, 23% (α(lc): 108°) (p < 0.001). The angle of the olfactory fossa and the position of the anterior ethmoid artery (free course: α(lc)=112° vs integrated into the skull base: α(lc)= 120°) was significantly different.

DISCUSSION

Surgical procedures in Keros type III where the height of the lateral lamella is much longer than in type II or type I, with an angle of nearly 107° between the lateral lamella and the cribriform plate, are expected to be safer in comparison with Keros type II with 116° and Keros type I with 131°.

Cone beam computed tomography for assessment of root length and marginal bone level during orthodontic treatment

OBJECTIVE

To evaluate the accuracy and precision of cone beam computed tomography (CBCT) with regard to measurements of root length and marginal bone level in vitro and in vivo during the course of orthodontic treatment.

MATERIALS AND METHODS

Thirteen patients (aged 12-18 years) from an ongoing study and a dry skull were examined with CBCT using multiplanar reformatting for measurements of root length and marginal bone level. For in vivo evaluation of changes in root length, an index according to Malmgren et al was used, along with a modification of this method.

RESULTS

The in vitro mean difference between physical and radiographic measurements was 0.05 mm (SD 0.75) for root length and -0.04 mm (SD 0.54) for marginal bone level. In vivo the error was <0.35 mm for root length determinations and <0.40 mm for marginal bone level assessments.

CONCLUSION

Despite changes in tooth positions, the CBCT technique yields a high level of reproducibility, enhancing its usefulness in orthodontic research.