Evaluation of Threshold Values for Root Canal Filling Voids in Micro-CT and Nano-CT Images

While several materials and techniques have been used to assess the quality of root canal fillings in micro-CT images, the lack of standardization in scanning protocols has produced conflicting results. Hence, the aim of this study was to determine a cutoff voxel size value for the assessment of root canal filling voids in micro-CT and nano-CT images. Twenty freshly extracted mandibular central incisors were used. Root canals were prepared with nickel titanium files to an ISO size 40/0.06 taper and then filled with a single cone (40/0.06 taper) and AH Plus sealer. The teeth were scanned with different voxel sizes with either micro-CT (5.2, 8.1, 11.2, and 16.73 μm) or nano-CT (1.5 and 5.0 μm) equipment. Images were reconstructed and analyzed with the NRecon and CTAn software. Void proportion and void volume were calculated for each tooth in the apical, middle, and coronal thirds of the root canal. Kruskal-Wallis and post hoc Mann–Whitney U tests were performed with a significance level of 5%. In micro-CT images, significantly different results were detected among the tested voxel sizes for void proportion and void volume, whereas no such differences were found in nano-CT images (p>0.05). Micro-CT images showed higher void numbers over the entire root length, with statistically significant differences between the voxel size of 16.73 μm and the other sizes (p<0.05). The values of the different nano-CT voxel sizes did not significantly differ from those of the micro-CT (5.2, 8.1, and 11.2 μm), except for the voxel size of 16.73 μm (p<0.05). All tested voxel sizes enabled the detection of root canal filling voids except for the voxel size of 16.73 μm. Bearing in mind the limitations of this study, it seems that a voxel size of 11.2 μm can be used as a reliable cutoff value for the assessment of root canal filling voids in micro-CT imaging.Publisher's Versio

3-dimensional Analysis of Regenerative Endodontic Treatment Outcome

A growing body of evidence supports the regeneration potential of dental tissues after regenerative endodontic treatment (RET). Nevertheless, a standard method for the evaluation of RET outcome is lacking. The aim of this study was to develop a standardized quantitative method for RET outcome analysis based on cone-beam computed tomographic (CBCT) volumetric measurements.EzEldeen M., Van Gorp G., Van Dessel J., Vandermeulen D., Jacobs R., ''3-dimensional analysis of regenerative endodontic treatment outcome'', Journal of endodontics, vol. 41, no. 3, pp. 317-324, March 2015 (2016 Journal of Endodontics Award for best article in the category of Clinical Research).status: publishe

A novel imaging approach to follow-up of condylar remodeling following bimaxillary surgery

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A systematic review on the innervation of peri-implant tissues with special emphasis on the influence of implant placement and loading protocols

OBJECTIVES To systematically review the available literature on the influence of dental implant placement and loading protocols on peri-implant innervation. MATERIAL AND METHODS The database MEDLINE, Cochrane, EMBASE, Web of Science, LILACS, OpenGrey and hand searching were used to identify the studies published up to July 2013, with a populations, exposures and outcomes (PEO) search strategy using MeSH keywords, focusing on the question: Is there, and if so, what is the effect of time between tooth extraction and implant placement or implant loading on neural fibre content in the peri-implant hard and soft tissues? RESULTS Of 683 titles retrieved based on the standardized search strategy, only 10 articles fulfilled the inclusion criteria, five evaluating the innervation of peri-implant epithelium, five elucidating the sensory function in peri-implant bone. Three included studies were considered having a methodology of medium quality and the rest were at low quality. All those papers reported a sensory innervation around osseointegrated implants, either in the bone-implant interface or peri-implant epithelium, which expressed a particular innervation pattern. Compared to unloaded implants or extraction sites without implantation, a significant higher density of nerve fibres around loaded dental implants was confirmed. CONCLUSIONS To date, the published literature describes peri-implant innervation with a distinct pattern in hard and soft tissues. Implant loading seems to increase the density of nerve fibres in peri-implant tissues, with insufficient evidence to distinguish between the innervation patterns following immediate and delayed implant placement and loading protocols. Variability in study design and loading protocols across the literature and a high risk of bias in the studies included may contribute to this inconsistency, revealing the need for more uniformity in reporting, randomized controlled trials, longer observation periods and standardization of protocols

Computer-based automatic classification of trabecular bone pattern can assist radiographic bone quality assessment at dental implant site

OBJECTIVE:: To develop and validate an automated classification method that determines the trabecular bone pattern at implant site based on three-dimensional bone morphometric parameters derived from CBCT images. METHODS:: 25 human cadaver mandibles were scanned using CBCT clinical scanning protocol. Volumes-of-interest comprising only the trabecular bone of the posterior regions were selected and segmented for three-dimensional morphometric parameters calculation. Three experts rated all bone regions into one of the three trabecular pattern classes (sparse, intermediate and dense) to generate a reference classification. Morphometric parameters were used to automatically classify the trabecular pattern with linear discriminant analysis statistical model. The discriminatory power of each morphometric parameter for automatic classification was indicated and the accuracy compared to the reference classification. Repeated-measures analysis of variances were used to statistically compare morphometric indices between the three classes. Finally, the outcome of the automatic classification was evaluated against a subjective classification performed independently by four different observers. RESULTS:: The overall correct classification was 83% for quantity-, 86% for structure-related parameters and 84% for the parameters combined. Cross-validation showed a 79% model prediction accuracy. Bone volume fraction (BV/TV) had the most discriminatory power in the automatic classification. Trabecular bone patterns could be distinguished based on most morphometric parameters, except for trabecular thickness (Tb.Th) and degree of anisotropy (DA). The interobserver agreement between the subjective observers was fair (0.25), while the test-retest agreement was moderate (0.46). In comparison with the reference standard, the overall agreement was moderate (0.44). CONCLUSION:: Automatic classification performed better than subjective classification with a prediction model comprising structure- and quantity-related morphometric parameters. ADVANCES IN KNOWLEDGE:: Computer-aided trabecular bone pattern assessment based on morphometric parameters could assist objectivity in clinical bone quality classification.status: publishe

Task‑related motivation and academic achievement in children and adolescents with ADHD

Academic impairment in individuals with attention-deficit/hyperactivity disorder (ADHD) is in part due to reduced motivation for academic tasks, which is likely to vary as a function of task characteristics. The current study employed a new questionnaire—the Child and Adolescent Motivational Profile (CHAMP)—to examine; (1) which task characteristic participants with ADHD perceive as most motivating relative to typically developing peers (TDP) and (2) whether these differences mediate academic functioning. 34 participants with ADHD and 435 TDP (8–16 years) completed the CHAMP. Academic achievement (grade point average) and self-reported positive/negative classroom experiences were recorded. No task characteristics were rated higher in terms of their motivational salience in the ADHD group than in the control sample. Marked/graded, Socially evaluated, Collaborative, Requiring focus and Cognitively challenging task characteristics were rated significantly lower by the ADHD group than controls. The lower rating of Socially evaluated was explained by comorbid ODD symptoms. Cognitively challenging was rated as particularly unmotivating by individuals with ADHD. ADHD was associated with a decreased GPA and a more negative classroom experience. The associations between ADHD and GPA/negative classroom experience were both partially mediated by scores on the Cognitively Challenging scale. For children and adolescents with ADHD tasks that are cognitively challenging were not particularly motivating. To increase task motivation, and improve academic performance of individuals with ADHD, it may be important to include rewarded task elements as they are appraised as particularly motivating by these individuals and this appraisal was similar to that of TDP.status: Published onlin

A comparative evaluation of cone beam CT and micro-CT on trabecular bone structures in the human mandible

OBJECTIVES: The main purpose of this study was to determine the accuracy of cone beam CT (CBCT) in measuring the trabecular bone microstructure, in comparison with micro-CT. The subobjective was to examine to what extent bone quality assessment is influenced by X-ray tube current and voltage settings as well as soft tissue surrounding the bone. METHODS: Eight human mandibular bone samples were scanned using three different clinical exposure protocol within water (W1-3) and without water (NW1-3) by a high-resolution (80 µm) CBCT machine (3D Accuitomo 170(®); Morita, Kyoto, Japan). Subsequently, the samples underwent micro-CT scanning (SkyScan 1174®; SkyScan, Antwerp, Belgium). After image acquisition, similar volumes of interest of the trabecular structures captured with CBCT and micro-CT were aligned with each other. Segmentation was then performed, and the morphometric parameters were quantified within the volumes of interest by CTAn software (CTAnalyser(®); SkyScan, Antwerp, Belgium). Descriptive statistical analyses and multiple comparisons between all protocols were applied in R software. RESULTS: High positive Pearson's correlation coefficients were observed between CBCT and micro-CT protocols for all tested morphometric indices except for trabecular thickness. No significant differences were observed between all exposure protocols except for trabecular separation. When examining the soft-tissue effect on trabecular bone structures, no significant differences between NW (1-3) and W (1-3) protocols were observed for all variables. CONCLUSIONS: The present study demonstrated the potential of high-resolution CBCT imaging for in vivo applications of quantitative bone morphometry and bone quality assessment. However, the overestimation of morphometric parameters and acquisition settings in CBCT must be taken into account.Van Dessel J., Huang Y., Depypere M., Rubira-Bullen I., Maes F., Jacobs R., ''A comparative evaluation of cone beam CT and micro-CT on trabecular bone structures in the human mandible'', Dentomaxillofacial radiology, vol. 42, 7 pp., 2013.status: publishe