Reduction Mandibuloplasty Along with Partial Masseter Muscle Resection: Masseter Muscle Response and Bone Regeneration.

OBJECTIVE: To compare the masseter muscle changes and bone regeneration between reduction mandibuloplasty along with partial masseter muscle resection and reduction mandibuloplasty alone. METHODS: Forty-seven patients who complained of prominent mandibular angle and hypertrophy masseter muscles (MMH) were divided into group 1 treated with reduction mandibuloplasty along with partial masseter muscle resection, and group 2 treated with reduction mandibuloplasty alone. Pre-5 days and long-term postoperative computed tomography data were collected, and the masseter muscle volume, hemi-mandible volume, and unilateral lower face width were measured. Patient satisfaction and complication were also evaluated. RESULTS: At long-term follow-up, group 1 showed a greater decrease in masseter volume (p < 0.001), and lower face width (p < 0.001), and less bone regeneration (p < 0.001) than group 2. Furthermore, patients in group 1 had higher satisfaction with the surgical outcome (p < 0.05). CONCLUSION: Reduction mandibuloplasty along with partial masseter muscle resection can achieve a slender frontal appearance and significantly decrease bone generation. For patients with MMH, reduction mandibuloplasty along with partial masseter muscle resection is an effective and predictable lower face reshaping surgery. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine Ratings, please refer to Table of Contents or online Instructions to Authors www.springer.com/00266 .

A Pilon Fracture With Fibular Head Dislocation Treated With the Use of 3D Preoperative Planning: A Case Report and Literature Review.

Pilon fractures with intact fibula have been associated with low-energy trauma. However, the compression force onto the ankle joint can damage the tibiofibular linkage as in a Maisonneuve fracture. Herein, we describe a case of a patient who had a pilon fracture (AO type 43 C3.2) without a fibular fracture. Three-dimensional preoperative simulation by reduction with the surface registration technique was performed as the fibular length was intact and there was no reference for the tibial length. The preoperative simulation revealed superior fibular head dislocation and shortening of the distal tibia. After emergency external fixation on the day of arrival, a 2-staged surgery was performed. During the first operation, the fibular head was reduced and the tibial posterolateral fragment was fixed to restore the tibia length. During the second operation, medial and anterolateral fragments were fixed in order to reduce joint surface of the distal tibia. In general, proximal fibular head fractures are easily overlooked. In the case of pilon fractures with severe length shortening of the tibia without a fibular fracture, a proximal tibiofibular injury should be suspected.

APPL1 negatively regulates bone mass, possibly by controlling the fate of bone marrow mesenchymal progenitor cells.

Adiponectin is an adipokine that can exert a regulatory function on bone metabolism. However, there are many contradictions between clinical and pre-clinical studies on adiponectin. APPL1 is an adaptor protein that can interact with adiponectin receptors. In the current study, we found that knockout of the Appl1 gene in male mice was associated with higher bone volume and numbers of trabeculae than in females or controls. The trabecular thickness, cortical thickness, ratio of bone volume/trabecular volume, cross-sectional bone area, and mean polar moment of inertia increased in Appl1 KO mice compared with wild-type mice. The number of osteoblasts increased but the number of adipocytes decreased in Appl1 KO mice. Knockdown of Appl1 impaired adipogenesis in bone marrow-derived mesenchymal stem cells. Mineralization was increased by knockdown of Appl1 during osteoblast differentiation. Data from differentiation-related genes showed results consistent with the in vivo effects. In summary, this study provides further clarification of the effect of the adiponectin signaling pathway on bone metabolism.

Evaluation of visual and computer-based CT analysis for the identification of functional patterns of obstruction and restriction in hypersensitivity pneumonitis.

BACKGROUND AND OBJECTIVE: To determine whether computer-based quantification (CALIPER software) is superior to visual computed tomography (CT) scoring in the identification of CT patterns indicative of restrictive and obstructive functional indices in hypersensitivity pneumonitis (HP). METHODS: A total of 135 consecutive HP patients had CT parenchymal patterns evaluated quantitatively by both visual scoring and CALIPER. Results were evaluated against: forced vital capacity (FVC), total lung capacity (TLC), diffusing capacity for carbon monoxide (DLCO ) and a composite physiological index (CPI) to identify which CT scoring method better correlated with functional indices. RESULTS: CALIPER-derived scores of total interstitial lung disease extent correlated more strongly than visual scores: FVC (CALIPER R = 0.73, visual R = 0.51); DLCO (CALIPER R = 0.61, visual R = 0.48); and CPI (CALIPER R = 0·70, visual R = 0·55). The CT variable that correlated most strongly with restrictive functional indices was CALIPER pulmonary vessel volume (PVV): FVC R = 0.75, DLCO R = 0.68 and CPI R = 0.76. Ground-glass opacity quantified by CALIPER alone demonstrated strong associations with restrictive functional indices: CALIPER FVC R = 0.65; DLCO R = 0.59; CPI R = 0.64; and visual = not significant. Decreased attenuation lung quantified by CALIPER was a better morphological measure of obstructive lung disease than equivalent visual scores as judged by relationships with TLC (CALIPER R = 0.63 and visual R = 0.12). All results were maintained on multivariate analysis. CONCLUSION: CALIPER improved on visual scoring in HP as judged by restrictive and obstructive functional correlations. Decreased attenuation regions of the lung quantified by CALIPER demonstrated better linkages to obstructive lung physiology than visually quantified CT scores. A novel CALIPER variable, the PVV, demonstrated the strongest linkages with restrictive functional indices and could represent a new automated index of disease severity in HP.

Predictors of clinical outcome in emphysema patients with atelectasis following endoscopic valve therapy: A retrospective study.

BACKGROUND AND OBJECTIVE: The aim of endoscopic valve therapy in patients with emphysema is complete lobar atelectasis of the most emphysematous lobe. However, even after the radiological advent of atelectasis, great variability in clinical outcomes can be observed. METHODS: The baseline clinical measures (vital capacity (VC), forced expiratory flow in 1 s (FEV1 ), residual volume (RV) and 6-min walk test (6-MWT)) and computed tomography variables (low attenuation volume (LAV) of the target lobe, LAV% of the target and the ipsilateral untreated lobe and LAV of the target lobe to LAV of the target lung and to LAV of the total lung) of 77 patients with complete atelectasis following valve therapy were retrospectively examined to determine their impact on patient´s outcome (changes in VC, FEV1 , RV and 6-MWT from baseline to the time of atelectasis). RESULTS: Low attenuation volume of the target lobe to LAV of the target lung predicts a significant FEV1 improvement in patients with complete lobar atelectasis following valve therapy. A 10% difference in that computed tomography predictor was associated with a 82-mL improvement in FEV1 (P = 0.006). Lower 6-MWT scores, low VC and high RV at baseline were significantly associated with greater improvement in the respective parameter (all P < 0.001). CONCLUSION: Low attenuation volume of the target lobe to LAV of the target lung and baseline clinical measures seem to significantly predict clinical outcomes in patients with complete lobar atelectasis following valve treatment.

Airways abnormalities in a prospective cohort of patients with rheumatoid arthritis.

BACKGROUND: Rheumatoid arthritis (RA) affects roughly 1% of the population and commonly involves the lungs. Of lung involvement in RA, interstitial lung disease (ILD) is well-known; however, airways disease in RA is relatively understudied. RESEARCH QUESTIONS: What are the baseline airways abnormalities in a prospective cohort of patients with RA based on pulmonary function tests (PFT), high-resolution CT scans (HRCT) and computational imaging analysis and are there associations between these abnormalities and respiratory symptoms? STUDY DESIGN AND METHODS: In this single-center study, 188 patients with RA without a clinical diagnosis of ILD underwent HRCT and PFT. Radiologists assessed HRCTs for airway abnormalities. Computational imaging via VIDA Vision software and in-house quantitative CT (qCT) analysis was applied to 147 HRCTs to quantify airway abnormalities. RESULTS: Airways obstruction (FEV1/FVC ratio < 0.7) was present in 20.7% of patients, and associated with older age, male sex and higher smoking rate. Radiologists identified airway abnormalities in 61% of patients-55% had bronchial wall thickening, 12% bronchiectasis, and 5% mosaic attenuation; these airways findings were associated with older age, male sex, lower FEV1, FVC, FEV1/FVC ratios, and higher rates of rheumatoid factor positivity. Prespecified qCT metrics (wall thickening % and emphysema %) correlated with PFT obstruction and more severe respiratory symptoms including shortness of breath and cough. INTERPRETATION: There were high rates of airways abnormalities in this prospective RA cohort based on three methods of detection. There were significant associations between qCT measures and respiratory symptoms. Airways disease may be an under-recognized extra-articular manifestation of RA and qCT may be a sensitive method to detect the clinical impact on respiratory symptoms.

Accuracy of multidetector computed tomography with maximum intensity projection technique in the assessment of fissure integrity.

BACKGROUND: Bronchoscopic lung volume reduction (BLVR) is a potential treatment for patients with severe emphysema, performed through the placement of unidirectional endobronchial valves (EBVs). Their benefits are only achieved in patients that significantly reduce lobar volume, and it is mandatory that the fissures are complete. Fissure evaluation is preferably done by computed tomography, but little is known if its evaluation corresponds to the anatomical findings. The aim of this study is to evaluate the accuracy of thoracic radiologists in the identification of complete fissures by multidetector computed tomography (MDCT) using maximum intensity projection (MIP) technique, compared with direct anatomical evaluation. METHODS: Prospective study, conducted in a single institution. Patients submitted to thoracic surgery had their fissures classified as complete or incomplete by thoracic surgeons and their preoperative chest scans evaluated by three radiologists, blinded for surgical evaluation. With the intraoperative categorization as a reference, the accuracy and concordance of the three thoracic radiologists' evaluation were calculated. The most experienced radiologist evaluated the fissures at two different moments to estimate the intra-observer agreement. RESULTS: There were included 67 patients, being 37 (55%) males, with a mean age of 64 years. The accuracy of radiological identification of complete fissures ranged from 76.8% for left posterior oblique fissure to 85.1% for left anterior oblique fissure, with the best performance achieved by the most experienced radiologist. The concordance of the radiological evaluation for fissure integrity compared to the surgical assessment (k) was 0.53-0.68. Intra-observer agreement ranged from 0.74 to 0.87. CONCLUSIONS: The evaluation of the fissure integrity by MDCT analysis using MIP technique by thoracic radiologists had high accuracy among the thoracic radiologists.

Grayscale image statistics of COVID-19 patient CT scans characterize lung condition with machine and deep learning.

Background: Grayscale image attributes of computed tomography (CT) of pulmonary scans contain valuable information relating to patients with respiratory ailments. These attributes are used to evaluate the severity of lung conditions of patients confirmed to be with and without COVID-19. Method: Five hundred thirteen CT images relating to 57 patients (49 with COVID-19; 8 free of COVID-19) were collected at Namazi Medical Centre (Shiraz, Iran) in 2020 and 2021. Five visual scores (VS: 0, 1, 2, 3, or 4) are clinically assigned to these images with the score increasing with the severity of COVID-19-related lung conditions. Eleven deep learning and machine learning techniques (DL/ML) are used to distinguish the VS class based on 12 grayscale image attributes. Results: The convolutional neural network achieves 96.49% VS accuracy (18 errors from 513 images) successfully distinguishing VS Classes 0 and 1, outperforming clinicians' visual inspections. An algorithmic score (AS), involving just five grayscale image attributes, is developed independently of clinicians' assessments (99.81% AS accuracy; 1 error from 513 images). Conclusion: Grayscale CT image attributes can be successfully used to distinguish the severity of COVID-19 lung damage. The AS technique developed provides a suitable basis for an automated system using ML/DL methods and 12 image attributes.

Predictors of calcification distribution in severe tricuspid aortic valve stenosis.

We investigated aortic valve calcification (AVC) distribution and predictors for leaflet calcification patterns in patients with severe tricuspid aortic valve stenosis undergoing transcatheter aortic valve replacement (TAVR). Patients undergoing routine multi-sliced computed tomography (MSCT) for procedural planning were enrolled. MSCT data were transferred to a dedicated workstation for evaluation (3mensio Structural Heart™, Pie Medical Imaging BV, Maastricht, The Netherlands) and analyzed. Participants were separated into asymmetrical (AC) and symmetrical (SC) leaflet calcification and potential predictors for calcification distribution were identified with univariate and multivariate regression analysis. 567 Participants with severe tricuspid AS were divided into asymmetrical (AC, n = 443; 78.1%) and symmetrical (SC, n = 124; 21.9%) AVC. In AC, the non-coronary cusp was the most calcified cusp (n = 238; 57.7%). SC is more common in females (AC/SC: 49.2% vs. 67.7%; p < 0.0001). AVC was more severe in patients with AC, who also have larger aortic root dimensions. Multivariate analysis depicted, inter alia, left ventricular outflow tract (LVOT) calcification < 25 Agatston units (OR 1.81 [1.09-3.00], p = 0.021), a mean pressure gradient < 36 mmHg (OR 1.77 [1.03-3.05], p = 0.039), and an annulo-apical angle > 67° (OR 1.68 [1.00-2.80], p = 0.049) as predictors for SC, although with only moderate predictive value. Data from this retrospective analysis indicate that SC occurs more frequently in females. The cumulative leaflet calcification burden is higher in patients with AC, who also present with larger aortic root dimensions. The predictive value for prominent calcification of different aortic valve cusps in AC patients was only low to moderate.Trial registration number: NCT01805739.

Comprehensive Perspective for Lung Cancer Characterisation Based on AI Solutions Using CT Images.

Lung cancer is still the leading cause of cancer death in the world. For this reason, novel approaches for early and more accurate diagnosis are needed. Computer-aided decision (CAD) can be an interesting option for a noninvasive tumour characterisation based on thoracic computed tomography (CT) image analysis. Until now, radiomics have been focused on tumour features analysis, and have not considered the information on other lung structures that can have relevant features for tumour genotype classification, especially for epidermal growth factor receptor (EGFR), which is the mutation with the most successful targeted therapies. With this perspective paper, we aim to explore a comprehensive analysis of the need to combine the information from tumours with other lung structures for the next generation of CADs, which could create a high impact on targeted therapies and personalised medicine. The forthcoming artificial intelligence (AI)-based approaches for lung cancer assessment should be able to make a holistic analysis, capturing information from pathological processes involved in cancer development. The powerful and interpretable AI models allow us to identify novel biomarkers of cancer development, contributing to new insights about the pathological processes, and making a more accurate diagnosis to help in the treatment plan selection.

Oral administration of melatonin contained in drinking water increased bone strength in naturally aged mice.

Melatonin has recently been found to be a possible new regulator of bone metabolism. However, the influence of melatonin in natural age-related osteoporosis has not been fully elucidated yet, although there have been some reports regarding postmenopausal osteoporosis with melatonin treatments. The present study investigated the effects of long-term melatonin administration during the aging process on bone metabolism. Using quantitative computed tomography methods, we found that the total bone density of both the femur metaphysis and diaphysis decreased significantly in 20-month-old male mice. In the metaphysis, both trabecular bone mass and Polar-Strength Strain Index (SSI), which is an index of bone strength, decreased significantly. Judging from bone histomorphometry analysis, trabecular bone in 20-month-old male mice decreases significantly with age and is small and sparse, as compared to that of 4-month-old male mice. Loss of trabecular bone is one possible cause of loss of bone strength in the femoral bone. In the metaphysis, the melatonin administration group had significantly higher trabecular bone density than the non-administration group. The Polar-SSI, cortical area, and periosteal circumference in the diaphysis was also significantly higher with melatonin treatments. Since the melatonin receptor, MT2, was detected in both osteoblasts and osteoclasts of the femoral bone of male mice, we expect that melatonin acts on osteoblasts and osteoclasts to maintain the bone strength of the diaphysis and metaphysis. Thus, melatonin is a potential drug for natural age-related osteoporosis.

Development of recycled polylactic acid/oyster shell/biomass waste composite for green packaging materials with pure natural glue and nano-fluid.

In this study, a diversified waste recycling system and a green processing technology are proposed. This research not only finds feasible solutions to alleviate environmental problems of plastic pollution and straw burning but also provides new reuse methods for oyster shell waste and hogwash oil. The developed noval biocomposite material is conducive to the green development of express industry. This paper evaluates the performance of materials from many aspects: X-ray computed tomography characterization, fundamental physical properties, mechanical properties, microscopic morphology, SEM morphology, and comprehensive performance of products. Two kinds of products with economic value are found. One is sample 4, which is suitable for making granular products due to its low cost (0.328$/500 g). Another is sample 13, which is suitable for manufacturing green packaging materials due to its excellent mechanical properties (tensile strength 14.15 MPa; elongation at break 12.68%; Young's modulus 8189.89 MPa). Based on the experimental results, the process of the composite is simulated to study the different strengthening mechanisms of arabic gum and poly(methyl vinyl ether-alt-maleic anhydride). Arabic gum uses chemical reaction and principle of similarity and intermiscibility to fuse with biomass to form homogeneous hybrid in the form of liquid gel. Poly(methyl vinyl ether-alt-maleic anhydride) indirectly adheres filler to the matrix through ring-opening reaction and structural similarity. The new emulsification system caused by arabic gum promotes the arabic gum and nano-fluid coupling cross-linking system to produce a decentralized cross-linked network and inhibit the pernicious molecular chain entanglement.

Pore Structure as a Response to the Freeze/Thaw Resistance of Mortars.

In this paper, the resistance to the freeze/thaw cycles for four groups of mortars (lime-LM, lime based-LBM, cement-CM, and aerated cement-ACM mortars) with different amount of mortar components within each group is quantified via a ratio of flexural/compressive strength after and before exposure to freeze/thaw cycles. Using a pore system obtained by three different methods (mercury intrusion porosimetry, X-ray micro-computed tomography analysis, and SEM (Scanning Electron Microscopy) analysis), an attempt was made to explain why some mortars achieved better resistance to freeze/thaw cycles than others. The mortars with lime as a binder in the composition (LM and LBM groups) did not survive the freezing and thawing regime, while no visible damage was recorded in samples of the CM and ACM group. It is concluded that the low initial value of the mechanical properties of the LM and LBM mortars, as well as the higher proportion of harmful pores (pores greater than 0.064 µm) compared to CM and ACM mortars are responsible for their poor durability. According the results of nanotomography, it is concluded that the most important factor influencing freeze/thaw resistance is pore connectivity-the higher the connectivity of the macropores, the higher the freeze/thaw resistance of the mortar. SEM analysis proved to be a very useful method for aerated cement mortars as it revealed the pore sizes that were not covered by mercury porosimetry and nanotomography.

Establishment of an osteoporosis model in tree shrews by bilateral ovariectomy and comprehensive evaluation.

Osteoporosis (OP) treatment has always been challenging for elderly menopausal females. An animal model with a closer genetic association to human OP is essential for treatment research. Given its close genetic association to primates, the tree shrew is a suitable candidate for meeting the requirements for such an animal model. In the present study, a tree shrew OP model induced by ovariectomy (OVX), was established. Evaluation by multiple analysis methods, including blood biochemical indicators, uterus coefficients, micro-computed tomography analysis, histochemical analysis and scanning electron microscopic observation indicated that OVX was an appropriate method to establish the OP model in tree shrews. In addition, the biomolecular characteristics of OVX-induced osteoporosis were also assessed by transcriptome sequencing and bioinformatics analysis. The present study provides the methods used to confirm the successful establishment of the OP model in tree shrew, and suggests that the OP model is appropriate for human OP research.

Nasal Septum and External Nasal Deformity Similarities in Monozygotic Twins and Paranasal Computed Tomography Analysis.

Since identical twins occur as a result of the division of one egg, they have the same genetic structure. Therefore, their phenotypes and sex are also always the same. However, due to the effect of environmental factors, some of the characteristics of twins living in different regions appear to develop differently. In our case of 17-year-old maternal twins, we emphasized that nasal pathologies carried a genetic background in terms of their similarity in septum deviation and external nasal deformity, which were determined to have occurred without a history of trauma. The article has also been presented at 10th Turkish Rhinology Congress, 22-25 May, 2014 Antalya, Turkey.

Volumetric mandibular change after angle ostectomy and outer cortex grinding.

BACKGROUND: Mandibular angle ostectomy is one of the most common surgical procedures for facial contouring in Asian women. However, some patients complain about mandibular angle hypertrophy recurrence after surgery. The present study evaluated volumetric change of the mandible after angle ostectomy and outer cortex grinding. METHODS: Twenty-four patients who underwent bilateral mandibular angle ostectomy and outer cortex grinding from 2013 to 2016 were enrolled. Three-dimensional computed tomography data were used to evaluate the preoperative, immediate postoperative, and long-term follow-up (≥12 months) volume of the mandible. The volumetric change between different groups was analyzed. RESULTS: The results of software measurements showed that the preoperative mandible volume was significantly larger than immediate and long-term postoperative volumes (P = 0.000), and there was no significant difference between immediate and long-term postoperative mandibular volume (P > 0.05). Mean bone regeneration at long-term follow-up was 1.42% ± 3.84% for those who underwent mandibular angle ostectomy with outer cortex grinding alone and 1.69% ± 2.45% on the left and 2.59% ± 3.61% on the right sides of patients who underwent this procedure along with advancement genioplasty. CONCLUSION: Mandibular angle ostectomy can effectively change the facial contour to achieve a more oval-shaped face favored by most Asians. Postoperative bone remodeling is mostly regenerated, although bone absorption did occur. However, the mean bone volume did not reach preoperative levels, and the difference between preoperative and long-term postoperative bone volume at follow-up (≥12 months) was significant.

ZrO2-toughened Al2O3 composites with better fracture and wear resistance properties.

In view of the importance of the fracture resistance and wear properties on the performance and durability in a number of engineering applications, we have analysed such properties of sintered zirconia toughened alumina with varying zirconia content of 5 and 15 wt.%. Using micro-computed tomography, homogenous particulate distribution of zirconia is established through 3D volume rendering of the sintered pellet and by 2D orthoslice view. Depending on zirconia content and MgO addition (sintering additive), an interesting combination of strength and toughness properties was recorded with the investigated materials. While explaining the origin of cracking on worn surfaces of optimized zirconia toughened alumina, theoretical calculations revealed that the maximum tensile stress at the trailing edge of sliding contact is higher than critical damage stress. Such analysis incorporates the effect of factors such as the internal stresses due to thermal expansion anisotropy of non-cubic Al2O3 matrix, mismatch in elastic modulus/thermal expansion and athermal ZrO2 phase transformation.

Quantitative CT analysis of honeycombing area in idiopathic pulmonary fibrosis: Correlations with pulmonary function tests.

OBJECTIVES: The 2011 official statement of idiopathic pulmonary fibrosis (IPF) mentions that the extent of honeycombing and the worsening of fibrosis on high-resolution computed tomography (HRCT) in IPF are associated with the increased risk of mortality. However, there are few reports about the quantitative computed tomography (CT) analysis of honeycombing area. In this study, we first proposed a computer-aided method for quantitative CT analysis of honeycombing area in patients with IPF. We then evaluated the correlations between honeycombing area measured by the proposed method with that estimated by radiologists or with parameters of PFTs. MATERIALS AND METHODS: Chest HRCTs and pulmonary function tests (PFTs) of 36 IPF patients, who were diagnosed using HRCT alone, were retrospectively evaluated. Two thoracic radiologists independently estimated the honeycombing area as Identified Area (IA) and the percentage of honeycombing area to total lung area as Percent Area (PA) on 3 axial CT slices for each patient. We also developed a computer-aided method to measure the honeycombing area on CT images of those patients. The total honeycombing area as CT honeycombing area (HA) and the percentage of honeycombing area to total lung area as CT %honeycombing area (%HA) were derived from the computer-aided method for each patient. RESULTS: HA derived from three CT slices was significantly correlated with IA (ρ=0.65 for Radiologist 1 and ρ=0.68 for Radiologist 2). %HA derived from three CT slices was also significantly correlated with PA (ρ=0.68 for Radiologist 1 and ρ=0.70 for Radiologist 2). HA and %HA derived from all CT slices were significantly correlated with FVC (%pred.), DLCO (%pred.), and the composite physiologic index (CPI) (HA: ρ=-0.43, ρ=-0.56, ρ=0.63 and %HA: ρ=-0.60, ρ=-0.49, ρ=0.69, respectively). CONCLUSIONS: The honeycombing area measured by the proposed computer-aided method was correlated with that estimated by expert radiologists and with parameters of PFTs. This quantitative CT analysis of honeycombing area may be useful and reliable in patients with IPF.

Post-euthanasia micro-computed tomography-based strain analysis is able to represent quasi-static in vivo behavior of whole vertebrae.

Three-dimensional image-based strain measurement in whole bones allows representation of physiological, albeit quasi-static, loading conditions. However, such work to date has been limited to specimens postmortem. The main purpose of this study is to verify the efficacy of deformable image registration of post-euthanasia strain to characterize the in vivo mechanical behavior of rat vertebrae. A micro-computed tomography-compatible custom loading device was used to apply 75 N load to a three-level caudal motion segment of a healthy rat. Loaded and unloaded micro-computed tomography scans were acquired in vivo and post-sacrifice. A micro-computed tomography-based deformable image registration algorithm was used to calculate vertebral strains live and post-euthanasia. No significant difference was found in the in vivo strains (-0.011 ± 0.001) and ex vivo strains (-0.012 ± 0.001) obtained from the comparisons of loaded and unloaded images (p = 0.3). Comparisons between unloaded-unloaded and loaded-loaded scans yielded significantly lower axial strains, representing the error of the method. Qualitatively, high strains were observed adjacent to growth plate regions in evaluating the loaded-unloaded images. Strain patterns in the loaded-loaded and unloaded-unloaded scans were inconsistent as would be expected in representing noise. Overall, live and dead loaded to unloaded comparisons yielded similar strain patterns and magnitudes. Point-wise differences in axial strain fields also supported this observation. This study demonstrated a proof of concept, suggesting that post-euthanasia micro-computed tomography-based strain analysis is able to represent the in vivo quasi-static behavior of rat tail vertebrae.

Influence of root canal preparation on formation of dentinal microcracks: a systematic review

Abstract The effect of root canal preparation technique on microcrack initiation is a controversial issue. This systematic review aimed to assess the role of root canal preparation techniques with different kinematics (manual, rotary, reciprocating, adaptive, self-adjusting file) on microcrack initiation. In vitro and in situ studies comparing the influence of at least two different root canal preparation techniques on the initiation of dentin microcracks were searched in PubMed/MEDLINE and SCOPUS up to June 5, 2018 without language and period restriction. Two authors independently reviewed all identified titles and abstracts for eligibility. Tables were generated to summarize the included studies, and the included studies were assessed for bias. Fifty-four (n=54) articles met the eligibility criteria. The results were classified according to the method used for microcrack evaluation, and most studies that used micro-computed tomography showed no formation of new cracks after root canal preparation. In general, the instrumentation techniques induced microcrack formation when the methods were destructive, irrespective of kinematics. In relation to the apex region, when the preparation working length was set as the root canal length subtracted of 1 mm, the risk of microcrack initiation reduces. The majority of the included studies had low risk of bias for all assessed domains. Our results seem to indicate that the various root canal preparation techniques considered in this study will not cause damage to the dental structure when adequately employed and the proper methodology is applied.

Resumo O efeito da técnica de preparo do canal radicular na iniciação e/ou propagação de microfissuras dentinárias é um tema controverso. Essa revisão sistemática teve como objetivo avaliar o papel das técnicas de preparo do canal radicular com diferentes cinemáticas (manual, rotatória, reciprocante, adaptativa e self-adjusting file) na iniciação e/ou propagação de microfissuras dentinárias. Estudos in vitro e in situ comparando a influência de pelo menos duas técnicas diferentes de preparo do canal radicular foram identificados no PubMed/MEDLINE e SCOPUS até 05 de junho de 2018 sem restrição de idioma e tempo. Dois autores revisaram de maneira independente todos títulos e resumos para elegibilidade dos estudos. Tabelas foram criadas para sumarizar os estudos incluídos e os estudos foram avaliados quanto ao risco de viés. Cinquenta e quatro (54) estudos enquadraram-se nos critérios de elegibilidade. Os resultados foram classificados de acordo com o método utilizado para avaliação das microfissuras. A maioria dos estudos que utilizaram micro-tomografia não demonstraram formação de novas microfissuras após preparo do canal radicular. Em geral, técnicas de instrumentação induziram formação de microfissuras quando os métodos de avaliação foram destrutivos, independente da cinemática. Em relação a região do ápice, quando comprimento de trabalho foi definido como o comprimento do canal menos 1 mm, o risco de indução de microfissuras é reduzido. A maioria dos estudos incluídos apresentaram baixo risco de viés para todos os domínios apresentados. Nossos resultados parecem indicar que as diferentes técnicas de preparo do canal radicular não causam danos a estrutura dental quando adequadamente utilizadas e a metodologia adequada é utilizada.