External and internal macromorphology in 3D-reconstructed maxillary molars using computerized X-ray microtomography

Morphological study of pulp cavity anatomy of canine teeth in domestic cats using micro-computed tomography

An understanding of the pulp cavity anatomy of individual teeth is essential for success during endodontic therapy. The objective of this study was to document pulp cavity anatomy and summarize numerical data of maxillary and mandibular canine teeth of domestic cats using micro-computed tomography (micro-CT). Thirty-nine canine teeth from eleven domestic cat cadaveric specimens were extracted and prepared for scanning. Segmentation of the pulp cavity was performed using the Avizo (v2022.2) software package. The morphological features of the pulp cavity including overall shape, configuration, presence of apical deltas and lateral canals was recorded. A quantitative analysis was performed on thirty-one teeth to explore associations between pulp cavity volume and length, apical delta length, maximum apical delta foramina number and cusp-to-tip length using a linear mixed model. Correlation between pertinent continuous variables was assessed using a Pearson's correlation test. Most pulp cavities exhibited varying curvature and ranged from a cylindrical configuration in the coronal third to an ovoid configuration in the middle to apical third. A ribbon-like flattened canal was observed in 6/31 teeth (19%). All canine teeth depicted an apical delta with various configurations except for two teeth that showed a single canal exiting at the apex. In 15/31 teeth (48%), the primary root canal within the apical delta could be clearly identified and in 16/31 (52%) the primary root canal was indiscernible. The results showed that the pulp cavities of maxillary canine teeth were significantly larger and longer and the cusp-to-tip length was longer, when compared to mandibular teeth. The apical delta length was negatively correlated to the volume of the pulp cavity. No specimens depicted lateral canals. This study revealed that the anatomy of the canine tooth pulp cavity in cats can vary considerably and should be a consideration when performing thorough debridement, shaping and obturation of the endodontic system.

Internal Morphology of Mandibular Second Premolars Using Micro-Computed Tomography

To examine root canal morphology of mandibular second premolars (Mn2P) of a mixed Swiss-German population by means of micro-computed tomography (micro-CT). Root canal configuration (RCC) of 102 Mn2P were investigated using micro-CT unit (µCT 40; SCANCO Medical AG, Brüttisellen, Switzerland) with 3D software imaging (VGStudio Max 2.2; Volume Graphics GmbH, Heidelberg, Germany), described with a four-digit system code indicating the main root canal from coronal to apical thirds and the number of main foramina. A total of 12 different RCCs were detected. 1-1-1/1 (54.9%) was most frequently observed RCC, followed by 1-1-1/2 (14.7%), 1-1-2/2 (10.8%), 1-2-2/2 (4.9%), 1-1-3/3 (3.9%), 1-1-1/3 (2.9%), 2-1-1/1 (2.9%) and less frequently 1-1-2/3, 1-2-1/2, 2-1-2/2, 1-1-2/5, 1-1-1/4 with each 1.0%. No accessory foramina were present in 35.3%, one in 35.3%, two in 21.6%, three and four in 2.9%, and five in 2.0%. In 55.9% Mn2Ps, accessory root canals were present in apical third and 8.8% in middle third of a root. Connecting canals were observed less frequently (6.9%) in apical and 2.9% in the middle third, no accessory/connecting canals in coronal third. Every tenth tooth showed at least or more than three main foramina. Almost two thirds of the sample showed accessory root canals, predominantly in apical third. The mainly single-rooted sample of Mn2Ps showed less frequent morphological diversifications than Mn1Ps.

Microcomputed Tomography Mineral Density Profile as Reference Standard for Early Carious Lesion Activity Assessment

Early caries diagnosis is crucial to treatment decisions in dentistry and requires identification of lesion activity: whether a carious lesion is active (progressively demineralizing) or arrested (progressively remineralizing). This study aimed to identify microtomographic (micro-CT) differences between active and arrested smooth surface enamel lesions, to quantify those micro-CT differences by creating thresholds for ex vivo caries activity assessment to serve as a future reference standard, and to validate those thresholds against the remaining sample. Extracted human permanent teeth (n = 59) were selected for sound surfaces and non-cavitated smooth surface carious lesions. Each surface was then examined for caries activity by calibrated individuals via visual-tactile examination using the International Caries Classification and Management System (ICCMS) activity criteria. Each tooth was scanned via micro-CT and the mineral density was plotted against lesion depth. The area under the curve (AUC) was calculated and represented the loss of density for the outermost 96 μm of enamel. AUC thresholds obtained from micro-CT were established to classify sound, remineralized, and demineralized surfaces against the gold standard examiner's lesion assessment of sound, inactive, and active lesions, respectively. The established AUC thresholds demonstrated moderate agreement with the assessment in identifying demineralized lesions (k = 0.45), with high sensitivity (0.73) and specificity (0.77). This study demonstrated quantifiable differences among demineralized lesions, remineralized lesions, and sound surfaces, which contributes to the establishment of micro-CT as a reference standard for caries activity that may be used to improve clinical and laboratorial dental caries evaluations.

To Analyze the Mesiobuccal Root Canal of Maxillary First Molar using Cone Beam Computed Tomography: An Ex-vivo Study

Aim and Objectives

The purpose of this study was to use cone bar CT to investigate the root trench morphology of two-hundred mesiobuccal permanent first molars in the maxilla.

Materials and Methods

The distobuccal and palatal roots were removed at the furcation in 250 maxillary first molars. The mesiobuccal roots were then imaged using cone beam computed tomography on all specimens. The specimens were analyzed and compared to one another." This study looked into the following factors. How Many Canals There Are and What Shape Those Canals Take Errors such as lateral canals, apical delta, calcified segments, and others.

Result

Vertucci's trench configuration, kinds I, II, III, IV, V, and VII, were seen in 30%, 20%, 5%, 6%, 7%, and 2.5% of the teeth, respectively. Calcified sections were found in the coronal third of the MB1 trench for eight of the samples, and in the central third for two of the samples. The MB1 trench did not have any calcifications at its very end. The coronal 33 percent of the MB2 trench was calcified in eight samples, but no calcifications were seen in the middle or upper thirds.

Conclusion

Noninvasively and with little radiation, a cone beam CT scan can help you learn about your root canal setup.

Effect of Different Preparation Techniques on Root Canal Geometry: An In Vitro Study

Aim and objective

To compare and evaluate canal preparation using hand stainless steel files, hand ProTaper files, and rotary ProTaper files for change in root canal geometry in terms of surface area and volume changes assessed by computed tomography.

Materials and methods

The present study was conducted in Nair Hospital and Dental College, Department of Pediatric and Preventive Dentistry in collaboration with insight CBCT, imaging technologies. A total of 36 extracted human primary mandibular second molars were collected from the Department of Pediatric and Preventive Dentistry. All the teeth were scanned using cone-beam CT (i-CAT CT Scanner Next Generation, Imaging Sciences International) preoperatively and postoperatively to assess the mean absolute change in surface area and mean change in the volume of all the canals at different levels with the use of hand stainless steel files, hand ProTaper and rotary ProTaper files.

Results

ProTaper instruments, both hand ProTaper and rotary ProTaper caused significant changes in the surface area in the coronal thirds and middle thirds of the canal when compared to hand stainless steel files. No difference was found in surface area and volume changes between hand ProTaper and rotary ProTaper instrumentation.

Conclusion

Use of ProTaper instruments for preparation of deciduous teeth can render benefit of an improved canal preparation to facilitate better obturation and successful root canal therapy.

How to cite this article

Bheda P, Kakade A, Takate V, et al. Effect of Different Preparation Techniques on Root Canal Geometry: An In Vitro Study. Int J Clin Pediatr Dent 2022;15(S-1):S71-S79.

A critical analysis of research methods and experimental models to study dentinal microcracks

The purpose of this narrative review was to discuss the scientific milestones that led to the current understanding of the root dentinal microcrack phenomenon based on the interplay between the usage of micro-computed tomography (micro-CT) as an analytical tool alongside a close-to-mouth experimental model. In 2009, reports on the development of dentinal microcracks in extracted teeth after root canal preparation triggered an awareness of the potential for vertical root fractures (VRFs) of endodontically treated teeth could be developed from defects created by the mechanical stress of nickel-titanium preparation systems on dentine. This assumption was taken for granted, even though no cause-effect relationship had been scientifically demonstrated. Since then, several studies using the sectioning method with extracted teeth have been published and the large discrepancy amongst their outcomes soon become evident. Moreover, the high frequency of reported dentinal microcracks largely contrasted with the clinical incidence of VRFs, raising doubts on their methodological reliability. Using micro-CT technology, it was demonstrated by several studies that, in extracted teeth, dentinal defects already existed before the endodontic procedures, indicating that the initial reports framed a non-existing cause-effect relationship between canal preparation and dentinal microcracks. Although these new findings contributed to a better comprehension of this phenomenon, the misconception that microcracks were the starting point for VRFs was only surpassed with a new in situ approach using fresh cadavers. Surprisingly, microcracks were not identified in sound teeth. As a conclusion, dentinal microcracks in extracted teeth can be considered a non-natural occurrence observed only in a laboratory set-up as a consequence of dehydration and storage conditions. Thus, dentinal microcracks shall not be considered as the starting point for VRFs as they do not manifest in non-extracted teeth. Identifying dentinal microcracks as a laboratory phenomenon highlights the impact of recent scientific developments to disclaim the clinical relevance of laboratory-obtained outcomes.

Contemporary Cleaning of the Root Canal System

This article provides a contemporary synopsis of effective cleaning of the root canal system, an essential stage of root canal treatment. It provides a clinical update on the current state of knowledge on cleaning of the root canal system, and presents an outline of essential theory and practical tips for achieving effective and safe cleaning of the root canal system.

Comparison of automatic and visual methods used for image segmentation in Endodontics: a microCT study

To calculate root canal volume and surface area in microCT images, an image segmentation by selecting threshold values is required, which can be determined by visual or automatic methods. Visual determination is influenced by the operator's visual acuity, while the automatic method is done entirely by computer algorithms.

Diagnostic Accuracy of Cone-Beam Computed Tomography and Periapical Radiography in Internal Root Resorption

INTRODUCTION

The aim of this study was to compare the diagnostic value of cone-beam computed tomography (CBCT) and periapical (PA) radiography in detecting internal root resorption.

METHODS AND MATERIALS

Eighty single rooted human teeth with visible pulps in PA radiography were split mesiodistally along the coronal plane. Internal resorption like lesions were created in three areas (cervical, middle and apical) in labial wall of the canals in different diameters. PA radiography and CBCT images were taken from each tooth. Two observers examined the radiographs and CBCT images to evaluate the presence of resorption cavities. The data were statistically analyzed and degree of agreement was calculated using Cohen's kappa (k) values.

RESULTS

The mean±SD of agreement coefficient of kappa between the two observers of the CBCT images was calculated to be 0.681±0.047. The coefficients for the direct, mesial and distal PA radiography were 0.405±0.059, 0.421±0.060 and 0.432±0.056, respectively (P=0.001). The differences in the diagnostic accuracy of resorption of different sizes were statistically significant (P<0.05); however, the PA radiography and CBCT, had no statistically significant differences in detection of internal resorption lesions in the cervical, middle and apical regions.

CONCLUSION

Though, CBCT has a higher sensitivity, specificity, positive predictive value and negative predictive value in comparison with conventional radiography, this difference was not significant.

Choice of diagnostic and therapeutic imaging in periodontics and implantology

Imaging forms an integral component for diagnosis of dental and in specific periodontal diseases. To date, intra-oral radiographic techniques are the main non-invasive diagnostic aids for the detection and assessment of internal changes in mineralized periodontal tissues like alveolar bone. These analog radiographic techniques suffer from inherent limitations like: Two dimensional projection, magnification, distortion, superimposition and misrepresentation of anatomic structures. The evolution of novel imaging modalities, namely cone beam computed tomography, tuned aperture CT empowered dental researchers to visualize the periodontium three dimensionally. This improves interpretation of structural and biophysical changes, ensures densitometric assessments of dentoalveolar structures including variations in alveolar bone density, and peri-implant bone healing more precisely. This detailed review, highlights current leading edge concepts, envisions a wide range of imaging modalities which pave the way for better understanding and early intervention of periodontal diseases.

Comparison of alternative image reformatting techniques in micro-computed tomography and tooth clearing for detailed canal morphology

INTRODUCTION

Micro-computed tomography (MCT) shows detailed root canal morphology that is not seen with traditional tooth clearing. However, alternative image reformatting techniques in MCT involving 2-dimensional (2D) minimum intensity projection (MinIP) and 3-dimensional (3D) volume-rendering reconstruction have not been directly compared with clearing. The aim was to compare alternative image reformatting techniques in MCT with tooth clearing on the mesiobuccal (MB) root of maxillary first molars.

METHODS

Eighteen maxillary first molar MB roots were scanned, and 2D MinIP and 3D volume-rendered images were reconstructed. Subsequently, the same MB roots were processed by traditional tooth clearing. Images from 2D, 3D, 2D + 3D, and clearing techniques were assessed by 4 endodontists to classify canal configuration and to identify fine anatomic structures such as accessory canals, intercanal communications, and loops.

RESULTS

All image reformatting techniques in MCT showed detailed configurations and numerous fine structures, such that none were classified as simple type I or II canals; several were classified as types III and IV according to Weine classification or types IV, V, and VI according to Vertucci; and most were nonclassifiable because of their complexity. The clearing images showed less detail, few fine structures, and numerous type I canals. Classification of canal configuration was in 100% intraobserver agreement for all 18 roots visualized by any of the image reformatting techniques in MCT but for only 4 roots (22.2%) classified according to Weine and 6 (33.3%) classified according to Vertucci, when using the clearing technique.

CONCLUSIONS

The combination of 2D MinIP and 3D volume-rendered images showed the most detailed canal morphology and fine anatomic structures.

An ex vivo comparison of digital radiography and cone-beam and micro computed tomography in the detection of the number of canals in the mesiobuccal roots of maxillary molars

INTRODUCTION

The purpose of this study was to compare digital periapical and cone-beam computed tomography (CBCT) images to determine the number of canals in the mesiobuccal root of maxillary molars and to compare these counts with micro computed tomography (μCT), which was also used to determine canal configuration.

METHODS

Digital periapical (RVG 6100), CBCT (9000 3D), and μCT images (the reference standard) were obtained of 18 hemi-maxillas. With periapical and CBCT images, 2 endodontists independently counted the number of canals in each molar and repeated the counts 2 weeks later. Teeth were extracted and scanned with μCT, and 2 additional endodontists, by consensus, determined the number and configuration of canals. The Friedman test was used to test for differences.

RESULTS

In mesiobuccal roots, 2 canals were present in 100% of maxillary first molars (13 of 13) and 57% of second molars (8 of 14), and 69% (9 of 13) and 100% (8 of 8) of these exited as 2 or more foramina. There was no difference in canal counts for original and repeat reads by the 2 observers with periapical (P = .06) and with CBCT (P = .88) and no difference when CBCT counts were compared with μCT counts (P = .52); however, when periapical counts were compared with μCT counts, there was a significant difference (P = .04).

CONCLUSIONS

For cadaver maxillary molars, μCT canal counts were significantly different from digital periapical radiograph counts but not different from Carestream9000 3D CBCT counts.

Quality of root fillings performed with two root filling techniques. An in vitro study using micro-CT

Objective.

The aim of this study was to compare the presence of voids in root fillings performed in oval and ribbon-shaped canals with two root filling techniques, lateral compaction technique (LCT) or hybrid technique (HT), a combination of a gutta-percha masterpoint and thermoplastic gutta-percha. Furthermore, the obturation time for the two techniques was evaluated.

Materials and methods.

Sixty-seven roots with oval and ribbon-shaped canals were prepared using Profile Ni-Ti rotary files. After preparation, the roots were randomly allocated to two groups according to root filling technique. All roots were filled with AH plus and gutta-percha. Group 1 was filled using LCT (n = 34) and group 2 was filled using HT (n = 33). The obturation time was measured in 30 cases evenly distributed between the two techniques. Voids in relation to the root canal fillings were assessed using cross-section images from Micro-computed Tomography scans.

Results.

All root canal fillings had voids. Permutation test showed no statistically significant difference between the two root filling techniques in relation to presence of voids (p = 0.092). A statistically significant difference in obturation time between the two techniques was found (p < 0.001).

Conclusion.

The present study found no statistically significant difference in percentage of voids between two root filling techniques. A 40% reduction in obturation time was found for the HT compared to the LCT.

Microcomputed tomographic analysis of the furcation grooves of maxillary first premolars

OBJECTIVES

The aims of this study were to conduct a morphometric analysis on the buccal furcation grooves in freshly extracted bifurcated maxillary first premolars (MFPs) and to correlate all anatomical measurements using microcomputed tomography.

MATERIALS AND METHODS

Twenty-three human MFPs with bifurcated canals were selected for this study. The specimens were analyzed with microcomputed tomography. The length, the beginning, and the ending of the grooves were measured. The minimum cross-sectional canal wall thickness in the grooves was located, and the width of the dentin thickness was calculated. All measurements were recorded and statistically analyzed.

RESULTS

The concavity of the grooves begins before the bifurcation site in 9/23 samples and after the bifurcation in 56.5% of samples. The groove length varied between 1.1-9 mm; the cross-sectional area with minimum palatal dentin thickness was 0.78±0.14 mm, which was located at a mean distance of 7.1 mm from the cementoenamel junction (CEJ) and 1.38 mm from the furcation.

CONCLUSIONS

The presence of the furcation grooves in the palatal aspects of the buccal roots of the MFPs was 100%. The length, depth, location, and width of the dentin thickness of the grooves varied in relation to tooth length, bifurcation, and CEJ. These parameters should be taken into consideration before any endodontic or restorative procedures are performed. Reducing dentin width too vigorously by intracanal instrumentation can predispose to vertical root fractures or perforations; if a post cannot be avoided, it should not extend 6.5 mm from the CEJ.

Quantitative visualization of a gas diffusion layer in a polymer electrolyte fuel cell using synchrotron X-ray imaging techniques

A gas diffusion layer (GDL) in a polymer electrolyte fuel cell (PEFC) is quantitatively visualized using synchrotron X-ray micro-computed tomography. For three-dimensional reconstruction, an adaptive threshold method is used. This method is compared with the conventional method, i.e. Otsu's method. Additionally, the spatial and temporal variations of the porosity distribution of the GDL under freeze-and-thaw cycles are investigated experimentally. The freeze-and-thaw cycles are established simply using a CRYO system and light source illumination, respectively. Structural defects are found to largely affect the porosity of the GDL. In addition, a cyclic porosity variation is observed in the GDL under freeze-and-thaw cycles. The heterogeneous porosity is irreversibly decreased with the progress of repetitive cycles.

The determination of the initial straight length in root canals of mandibular premolars--an in vitro study

The aim of the present roentgenographic in vitro study was to determine the initial straight length from the cemento-enamel junction (CEJ) to the appearance of a root canal curvature in human mandibular premolars. A total number of 282 mandibular premolars were examined. Exclusion criteria comprised root caries, extensive restorations and endodontically treated teeth. The teeth were fixed and digitally radiographed by means of a specially developed fixation device with standardized and reproducible distances with the parallel technique (Heliodent MD; Merlin 2.1). The distances from the CEJ to the first curvature (> 5°) (distance I), from the first curvature to a second curvature (distance II), and from the first or second curvature to the radiological apex (distance III) were recorded. The lengths of the initial straight distance and the appearance of a curvature were statistically analyzed and related to each other. In first mandibular premolars, the mean value for distance I was 10.9 mm, for distance II 3.7 mm and for distance III 3.04 mm. The mean values for the second mandibular premolars were 1.1 mm in distance I, 4.3 mm in distance II and 3.1 mm in distance III. No statistically significant differences between left and right mandibular premolars could be observed regarding the canal curvature location and the angle values. The results of this investigation show that curvatures are increasingly observed 9 to 12 mm from the original path in mandibular premolars.

Three-rooted premolar analyzed by high-resolution and cone beam CT

OBJECTIVES

The aim of this study was to analyze the variations in canal and root cross-sectional area in three-rooted maxillary premolars between high-resolution computed tomography (μCT) and cone beam computed tomography (CBCT).

MATERIALS AND METHODS

Sixteen extracted maxillary premolars with three distinct roots and fully formed apices were scanned using μCT and CBCT. Photoshop CS software was used to measure root and canal cross-sectional areas at the most cervical and the most apical points of each root third in images obtained using the two tomographic computed (CT) techniques, and at 30 root sections equidistant from both root ends using μCT images. Canal and root areas were compared between each method using the Student t test for paired samples and 95 % confidence intervals.

RESULTS

Images using μCT were sharper than those obtained using CBCT. There were statistically significant differences in mean area measurements of roots and canals between the μCT and CBCT techniques (P < 0.05). Root and canal areas had similar variations in cross-sectional μCT images and became proportionally smaller in a cervical to apical direction as the cementodentinal junction was approached, from where the area then increased apically.

CONCLUSION

Although variation was similar in the roots and canals under study, CBCT produced poorer image details than μCT.

CLINICAL RELEVANCE

Although CBCT is a strong diagnosis tool, it still needs improvement to provide accuracy in details of the root canal system, especially in cases with anatomical variations, such as the three-rooted maxillary premolars.

Microcomputed tomography analysis of mesiobuccal orifices and major apical foramen in first maxillary molars

OBJECTIVE

Aim of the study was to determined by microcomputed tomography (µCT) the horizontal distance between the main (MB1) and the second mesiobuccal canal (MB2) orifices, the vertical distance between the MB1 and MB2 orifices planes, and the distance between the anatomic apex and major apical foramen (AF). Furthermore, we characterized the entire internal and external anatomy of the MB, distalbuccal (DB) and palatal (P) maxillary first molars roots.

MATERIALS AND METHODS

Twenty-two intact extracted first maxillary molars were scanned by X-ray computed transaxial µCT and then 2D and 3D images were processed and analyzed.

RESULTS

The results showed that 77.27% of the mesiobuccal (MB) roots presented a second MB canal, and 29.41% of the MB2 were independent from the MB1 canals. In 15 teeth, there were three root canal orifices on the chamber floor, and 10 of these teeth presented MB2 canals. The mean vertical distance between the MB1 and MB2 planes was 1.68 ± 0.83 mm. Seven teeth had four orifices. The mean horizontal interorificial distance between the MB1 and MB2 orifices was 1.21 ± 0.5 mm. Accessory canals were observed in 33.33% of the roots, loops in 6.06%, while isthmuses were found in 15 of the 22 MB roots. Of the total roots, 74.24% presented one foramen, while all of the roots showed a major apical foramen that was not coincident with the anatomic apex.

CONCLUSIONS

Our µCT analysis provided interesting features on the horizontal and vertical distance between the MB1 and MB2 orifices and on the distance of AF and anatomic apex.

CLINICAL RELEVANCE

These results have an important clinical value because might support the endodontist in the recruitment, negotiation and obturation of maxillary first molar canal system.

Three-dimensional analysis of the pulp cavity on surface models of molar teeth, using X-ray micro-computed tomography

AIM

The purpose of this study was to investigate the scanning and segmentation precision of surface models of molars for the detection of small volumes, such as the reduced pulp cavity; formation of mineral deposits; detection of narrow root canals and to improve the clinical and morphological understanding of the number of root canals and their configuration.

METHODS

Eighteen human molars were scanned using X-ray micro-computed tomography. The reconstruction of the surface models had a precision of <1 voxel, using three-dimensional software and quantitative color mapping. In order to relate the measurements to changes over time the size of the pulp chambers was classified in two well-defined groups.

RESULTS

The mineral deposits were more evenly distributed in small pulp chambers than in large, but complete root canal calcification was never observed. No difference was observed in the material with respect to the presence of intra-radicular connections. In upper molars, a second mesiobuccal canal (mb(2)) frequency of 91% was found. The difference in length between the first mesiobuccal canal (mb(1)) and mb(2) was <1 mm. The number of root canals could be related to the number of root cones.

CONCLUSION

In summary, three-dimensional surface models were made with a high precision; an increased accumulation of mineral deposits was noted in molars with small pulp chambers and combined with the consistent pattern of intra-radicular connections, the potential endodontic treatment complexity is underlined in such cases. Finally, an improved understanding of root canal prevalence was reached, when merging well-defined definitions on root morphology and clinical classification systems.

Diagnostic performance of the visual caries classification system ICDAS II versus radiography and micro-computed tomography for proximal caries detection: an in vitro study

OBJECTIVES

The purpose of this study was: (a) to compare the visual caries classification system ICDAS II with conventional (CR) and digital radiography (DR) for diagnosis of non-cavitated caries on free proximal surfaces, (b) to examine the potential of micro-computed tomography (MCT) to substitute histological examination for the in vitro caries assessment.

METHODS

Both proximal surfaces of 20 teeth received classification separately by two examiners by means of the diagnostic modalities examined. The teeth were sectioned and assessed for depth of the lesion. The modalities were compared in terms of degree of inter-examiner agreement, sensitivity, specificity, accuracy, positive and negative predictive value and validity. Two diagnostic thresholds were applied: no caries versus all caries scores (D1), and no dentin caries versus dentin caries (D3).

RESULTS

The weighted kappa values for inter-examiner reproducibility for all diagnostic modalities were 0.51-0.81. Visual examination (ICDAS II) reached significant higher sensitivity (0.92-0.96) and negative predictive value (0.9-1) than radiography. Likewise, the radiographic modalities presented significantly higher specificity (0.93-1) and positive predictive values (0.92-1) than the ICDAS II criteria. The overall accuracy performance of radiographic modalities was related to the diagnostic threshold. MCT did not agree with histological validation at each disease severity scale.

CONCLUSIONS

The ICDAS II criteria are a promising tool for caries diagnosis on free proximal surfaces. DR and CR radiography present comparable performance. Furthermore, MCT is not capable of constituting a reliable alternative to histological examination for caries research.

Evaluation of apical deviation in root canals instrumented with K3 and ProTaper systems

Objectives:

this study evaluated the apical deviation of curved root canals instrumented with K3 and ProTaper systems.

Material and methods:

twenty root canals of human maxillary and mandibular first molars were employed, which were divided into 2 groups: group A (10 teeth) was instrumented with the K3 system, and group B (10 teeth) with the ProTaper system. Evaluation of deviation was performed by double radiographic exposure. Radiographs were achieved before and after instrumentation, with 0.3-second, thus allowing superimposition of images. Three-dimensional computerized tomograph was performed in 3 specimens in each group, as an additional means to evaluate the apical deviation.

Results:

were evaluated by the parametric test Student-Newman-Keuls at 5%, which did not reveal significance between groups concerning the apical deviation. The results of computerized tomograph images demonstrated that the larger deviation of the root canal occurred at the distolingual area for both systems.

Conclusions:

both techniques produced a mild apical deviation. Computerized microtomography was shown to be accurate for experimental endodontics studies.

Anomalous mandibular premolars: a mandibular first premolar with three roots and a mandibular second premolar with a C-shaped canal system

AIM

To describe unusual variations in the root morphology and root canal systems of mandibular first and second premolar teeth extracted for orthodontic reasons.

SUMMARY

Normally mandibular first and second premolar teeth have single roots with single canals. A 15-year-old patient presented for orthodontic treatment and two mandibular premolar teeth were examined post-extraction. The mandibular first premolar exhibited three distinct, separate roots and the mandibular second premolar exhibited a C-shaped root canal system. The coronal morphology of each of the mandibular premolars revealed dimensions and anatomy within normal limits. The incidence of a three-rooted mandibular first premolar is approximately 0.2%.

KEY LEARNING POINTS

* Thorough clinical and radiographic interpretation is important in recognizing anomalous root and root canal systems. * The most common forms of root and canal systems and its aberrations must be understood to realize variations from normal do occur. * Successful root canal treatment requires an accurate diagnosis of the root canal system using all available aids. * Value of microcomputed tomography in the study of anatomy ex vivo and cone-beam tomography in clinical endodontics of complex premolar cases is increasing.

Quantitative measurements obtained by micro-computed tomography and confocal laser scanning microscopy

OBJECTIVES

To compare measurements obtained by micro-CT with those obtained by confocal laser scanning microscope in simulative internal resorption cavities.

METHODS

An extracted human maxillary central incisor tooth was divided into two in the coronal plane. Four artificial internal resorption cavities were prepared with standardized burs on each section, and diameters and volumes were measured using a laser scanning electron confocal microscope and a desktop cone beam micro-CT-40. Differences between means of quantitative measurements for both methods were tested using the paired t-test; the correlation between quantitative measurements was tested by regression analysis.

RESULTS

Mean diameter and volume differences between the two methods were 0.061 mm and 0.004 mm(3), respectively. Average diameter and volume calculations obtained by micro-CT were significantly lower (P < 0.001 for diameter and P < 0.01 for volume). A significantly strong relationship was found in the average diameters (R(2) = 92.9%) and calculated volumes (R(2) = 91%), (P < 0.001).

CONCLUSIONS

Although a strong correlation between both methods was found, micro-CT significantly underestimated the diameters and volumes.

Imaging applications of synchrotron X-ray phase-contrast microtomography in biological morphology and biomaterials science. I. General aspects of the technique and its advantages in the analysis of millimetre-sized arthropod structure

Synchrotron-generated X-rays provide scientists with a multitude of investigative techniques well suited for the analysis of the composition and structure of all types of materials and specimens. Here, we describe the properties of synchrotron-generated X-rays and the advantages that they provide for qualitative morphological research of millimetre-sized biological organisms and biomaterials. Case studies of the anatomy of insect heads, of whole microarthropods and of the three-dimensional reconstruction of the cuticular tendons of jumping beetles, all performed at the beamline ID19 of the European Synchrotron Radiation Facility (ESRF), are presented to illustrate the techniques of phase-contrast tomography available for anatomical and structural investigations. Various sample preparation techniques are described and compared and experimental settings that we have found to be particularly successful are given. On comparing the strengths and weaknesses of the technique with traditional histological thin sectioning, we conclude that synchrotron radiation microtomography has a great potential in biological microanatomy.