Delphine Maret

Validation of Cone Beam Computed Tomography as a Tool to Explore Root Canal Anatomy

INTRODUCTION Cone beam computed tomography (CBCT) can provide dentists with high-quality 3-dimensional images of dental structures because of its high spatial resolution. The reconstructions of root canal systems given by the Kodak 9000 3D were compared with histologic sections to evaluate the reliability of the reconstructions. METHODS Nine intact freshly extracted teeth with closed apexes were scanned by using the Kodak 9000 3D (spatial resolution 76 microm and 14 bits contrast resolution). After reconstruction of the volumes, the outline of the root canals was defined by segmentation. Histologic sections were then made of each specimen at predetermined levels. After digitization (resolution, 0.5-1 microm), 2-dimensional cone beam reconstructions were compared with the outline of the canals obtained by histologic sections by using areas and Ferets diameters. The statistical analysis was performed by using the Pearson correlation coefficient. RESULTS Strong to very strong correlation was found between the data acquired by using CBCT and histology: r (area) = 0.928; r (diameter) = 0.890. CONCLUSIONS The Kodak 9000 3D appears to be a very interesting, reliable, noninvasive measuring tool that can be used in all spatial planes.

Accuracy of 3D Reconstructions Based on Cone Beam Computed Tomography

Three-dimensional imaging of teeth will increase its impact in clinical practice if reconstructions are metrically accurate. We hypothesized that, with cone beam computed tomography (CBCT) data, three-dimensional images of teeth can be reconstructed with the same accuracy and precision as with in vitro micro-computed tomography (micro-CT) data acquisition, the current reference standard. We used a sample of CBCT and micro-CT data taken of tooth germs. Volumes obtained with CBCT and micro-CT devices were statistically similar (n = 120, Passing-Bablok regression). Geometric deviations between CBCT and micro-CT three-dimensional surface reconstructions did not show any areas of important and systematic errors. Future investigations with the use of larger samples may also demonstrate that CBCT data will be helpful for a more in-depth study of other aspects of dental morphology—for example, assessing tooth development. With sufficient accuracy for clinical situations, potential future medical applications of such measurements with CBCT are envisaged.

Ethics in systematic reviews

Since its introduction by the Nuremberg Code and the Declaration of Helsinki, the place held by ethics in biomedical research has been continuously increasing in importance. The past 30 years have also seen exponential growth in the number of biomedical articles published. A systematic review of the literature is the scientific way of synthesising a plethora of information, by exhaustively searching out and objectively analysing the studies dealing with a given issue. However, the question of ethics in systematic reviews is rarely touched upon. This could lead to some drawbacks, as systematic reviews may contain studies with ethical insufficiencies, may be a possible way to publish unethical research and may also be prone to conflict of interest. Finally, informed consent given for an original study is not necessarily still valid at the systematic review level. There is no doubt that routine ethical assessment in systematic reviews would help to improve the ethical and methodological quality of studies in general. However, ethical issues change so much with time and location, and are so broad in scope and in context that it appears illusory to search for a universal, internationally accepted standard for ethical assessment in systematic reviews. Some simple suggestions could nevertheless be drawn from the present reflection and are discussed in the paper.

Comparison of the Accuracy of 3-dimensional Cone-beam Computed Tomography and Micro–Computed Tomography Reconstructions by Using Different Voxel Sizes

INTRODUCTION Cone-beam computed tomography (CBCT) data are, in principle, metrically exact. However, clinicians need to consider the precision of measurements of dental morphology as well as other hard tissue structures. CBCT spatial resolution, and thus image reconstruction quality, is restricted by the acquisition voxel size. The aim of this study was to assess geometric discrepancies among 3-dimensional CBCT reconstructions relative to the micro-CT reference. METHODS A total of 37 permanent teeth from 9 mandibles were scanned with CBCT 9500 and 9000 3D and micro-CT. After semiautomatic segmentation, reconstructions were obtained from CBCT acquisitions (voxel sizes 76, 200, and 300 μm) and from micro-CT (voxel size 41 μm). All reconstructions were positioned in the same plane by image registration. The topography of the geometric discrepancies was displayed by using a color map allowing the maximum differences to be located. RESULTS The maximum differences were mainly found at the cervical margins and on the cusp tips or incisal edges. Geometric reconstruction discrepancies were significant at 300-μm resolution (P = .01, Wilcoxon test). CONCLUSIONS To study hard tissue morphology, CBCT acquisitions require voxel sizes smaller than 300 μm. This experimental study will have to be complemented by studies in vivo that consider the conditions of clinical practice.

Cone-Beam Computed Tomography: A useful tool for dental age estimation?

Assessment of oral hard tissues can be of great help in determining the age of an individual. The development and physiological aging of teeth provide many clues for estimating age, in methods that are mainly based on conventional radiography. Although these conventional techniques reveal information on the anatomical and pathological characteristics, they only show two-dimensional images of a system that originally exists in three dimensions. With the growth and development of three-dimensional imaging, it has become possible to include measurements such as volumetric data, which give a better grasp of the continuous process of tooth mineralization. Up to now, these measurements have been obtained in vitro using micro-computed tomography (micro-CT) but three-dimensional imaging has recently been enriched by a new technique: Cone-Beam Computed Tomography (CBCT), which is devoted to the maxillo-facial sphere. These acquisitions may offer real potential for exploiting and analyzing volumetric measurements of teeth. We hypothesize that, using CBCT acquisitions, multiple regression analysis including quantitative volumetric measurement of various parts of each tooth can be useful to determine significant variables for dental age estimation in living subjects. Currently, CBCT examinations are being performed and contain important information for the quantitative study of dental tissue. Although CBCT examinations are conducted in the first intention of making a clinical diagnosis or prognostic evaluation, they could be used as an initial database for the measurement of dental volumes and their ratios, thus furnishing preliminary evaluations and information. Multiple regression analysis requires the constitution of a larger sample sizes which may demonstrate that CBCT data can be helpful to study other aspects of dental morphology in greater depth, especially dental growth. In this hypothesis, integration with a larger network system would be necessary. CBCT data could be helpful in defining new parameters for the rating of dental development, for a quantitative description of the fractions of crown and root and could offer new research oriented towards various aspects of teeth and jaws, thanks to its broad sampling possibilities.

Interrelationships in the Variability of Root Canal Anatomy among the Permanent Teeth: A Full-Mouth Approach by Cone-Beam CT

Objectives In endodontic practice, clinicians should be aware of possible root canal anatomic variations. The aim of this study was to assess using CBCT acquisitions regarding whether one root canal anatomy of a tooth is associated with a specific anatomy of another tooth. Methods A total of 106 CBCT acquisitions were obtained using a CBCT scanner with 200μm voxel size. Numbers of roots and canals of the entire dentition were described. Bivariate analyses and logistic regressions were conducted to explore root canal anatomy on one tooth according to age, gender, jaw, side and the others teeth. Multiple correspondence analysis (MCA) was performed to correlate the different numbers of canals profiles. Results A total of 2424 teeth were analyzed. Independently from the other variables, the presence of an additional root canal on a mandibular incisor increases the risk of having an additional root canal on a mandibular premolar (OR [95%] 3.7 [1.0;13.2]). The mandibular molar variability increases in women compared to men (OR [95%] 0.4 [0.1; 0.9]). MCA showed correspondence between 2-canals maxillary incisor and canines and 5-canals maxillary molars, and some correlation between additional canal on maxillary and mandibular premolars. Conclusions Although CBCT examinations are conducted in the first intention of making a diagnosis or prognostic evaluation, medium FOV acquisitions could be used as an initial database thus furnishing preliminary evaluations and information. In endodontic practice, clinicians should be aware of possible root canal anatomic variations. The visualization of all canals is considered essential in endodontic therapy. The use of multi-correspondence analysis for statistics in endodontic research is a new approach as a prognostic tool.

Effect of fixed orthodontic appliances on salivary microbial parameters at 6 months: a controlled observational study

Objective The aim of this study was to assess the microbial changes in children with fixed orthodontic appliances compared with a control group of children without orthodontic treatment. Material and Methods Ninety-five children, aged between 12 and 16 years, participated in this study. Forty-eight subjects were fitted with fixed orthodontic appliances and forty-seven were free of any such appliances. The follow-up was 6 months for all children. The association between orthodontic appliances and high levels of Streptococcus mutans and Lactobacillus spp was assessed with logistic regression models, taking age, sex, pH and buffer capacity into account. Results Differences at baseline between the two groups were not statistically significant. We found that wearing a fixed orthodontic appliance was associated with high levels of Streptococcus mutans and Lactobacillus spp (adjusted OR: 6.65, 95% CI [1.98-22.37]; 9.49, 95% CI [2.57-35.07], respectively), independently of other variables. Conclusion The originality of the present epidemiological study was to evaluate the evolution of salivary microbial parameters in a population of children with fixed orthodontic appliances. Our results show an increase of Streptococcus mutans and Lactobacillus spp values during the follow-up. The whole dental workforce should be aware that preventive measures are of paramount importance during orthodontic treatment.

Prevalence of Apical Bone Defects and Evaluation of Associated Factors Detected with Cone-beam Computed Tomographic Images.

INTRODUCTION Cone-beam computed tomographic (CBCT) imaging has been shown to be accurate for detecting apical bone defects (ABDs). Medium field of view CBCT imaging may provide apical images of the whole oral cavity at a resolution that is sufficient to allow ABDs to be located and measured. The aim of the work presented was to calculate the prevalence of ABDs from CBCT images as well as to assess some associated factors and their measurement. METHODS One hundred CBCT data sets with a voxel size of 0.2 mm were analyzed by 2 evaluators according to a standardized reading protocol. The number of maxillary and mandibular teeth, the presence of endodontic treatment, and the presence of ABDs associated with endodontic treatment were identified, and the presence of intraradicular posts was documented. The size of ABDs detected was measured, and they were classified according to the Cone Beam Computed Tomography Periapical Index. RESULTS A total of 2368 teeth and 100 subjects were analyzed. The prevalence of ABDs in subjects was 78%; in 8.6% of the sample teeth, ABDs were present, and 38.2% of endodontically treated maxillary molars were affected by it. Endodontic treatment was significantly associated with an increased risk for the presence of an ABD (P = .0001); 40.8% of endodontically treated teeth were associated with an ABD. This rate increased to 85.9% in endodontically treated maxillary molars. Placement of a post was significantly associated with the presence of an ABD (P = .003). The most frequent lesions were those with diameters between 2 and 4 mm (39.2%). CONCLUSIONS There are only few studies on the prevalence of ABDs using CBCT analysis. This study in a French population shows a high prevalence of ABDs, especially on endodontically treated molars. The most effective way to exhaustively detect such defects is with CBCT imaging. Moreover, CBCT images show details of the extent of bone loss, thus providing information valuable for the therapeutic decision and details that could help with the prognosis.

A panorama of tooth wear during the medieval period.

Tooth wear is a natural phenomenon and a universal occurrence that has existed from the origin of humankind and depends on the way of life, especially diet. Tooth wear was very serious in ancient populations up to the medieval period. The aim of this paper is to present a global view of tooth wear in medieval times in Europe through different parameters: scoring systems, quantity and direction of wear, gender, differences between maxilla and mandible, relations with diet, caries, tooth malpositions and age.

Fetal age estimation using MSCT scans of the mandible

The purpose of this study was to examine a documented fetal collection, to carry out morphometric analysis of femoral length and of the mandible, and to develop diagnostic standards for estimating fetal age at death based on multislice computed tomography (MSCT) reconstructions. The sample was composed of 81 fetuses, whose ages were recorded in weeks of amenorrhea (WA) between 20 to 40 WA. The measurements made were femoral length (FL) and six distances and four angles of the mandible. Femoral length was measured in 81 fetuses (39 females and 42 males). Morphometric study of the mandible was carried out in 65 fetuses (31 females and 34 males), as the mandible was missing in 16 fetuses. R software was used for statistical analyses. Coefficient correlation (R2) and linear regression formulas were calculated. Intra-observer and inter-observer variabilities were very satisfactory (intra-class correlation coefficient ≥0.95). Our method appears to be reliable and reproducible. Femoral length was most strongly correlated with age (R2 = 0.9). The measurement of six distances and four mandible angles from four landmark positions showed a correlation similar to the femoral length correlation (R2 ≥ 0.72). The results of this study agreed with those of the literature. We conclude that the mandible is a reliable indicator for estimating fetal age at death. Moreover, MSCT has been shown to be an innovative and reliable technology for this purpose.