Evaluation of the marginal and internal gaps of partially crystallized versus fully crystallized zirconia-reinforced lithium silicate CAD-CAM crowns: An in vitro comparison of the silicone replica technique, direct view, and 3-dimensional superimposition analysis.

STATEMENT OF PROBLEM: The crystallization process of lithium disilicate crowns has been reported to cause dimensional change, but whether the fit of chairside computer-aided design and computer-aided manufactured (CAD-CAM) zirconia-reinforced lithium silicate crowns is affected is unclear. PURPOSE: The purpose of this in vitro study was to evaluate with a 3-dimensional superimposition analysis technique the marginal and internal adaptation of fully crystallized versus partially crystallized zirconia-reinforced lithium silicate ceramic CAD-CAM fabricated crowns. Additionally, the silicone replica technique and direct viewing of marginal gap values were compared with the 3-dimensional superimposition analysis technique. MATERIAL AND METHODS: The marginal and internal adaptation of a fully crystallized zirconia-reinforced lithium silicate (CELTRA DUO) were compared with those of a partially crystallized zirconia-reinforced lithium silicate (VITA SUPRINITY) after crystallization. Sixteen crowns (n=8) were fabricated with a chairside CAD-CAM system. The crowns and die and crown assembly were scanned with an optical scanner for the 3-dimensional superimposition analysis. Four hundred sixty-eight measurements were made for each crown, 78 in each 2-dimensional section. Marginal discrepancy was measured by using the direct viewing technique. The internal adaptation of the shoulder area, axial space, and occlusal space was measured by using the silicone replica technique. Both gap values were compared with the 3-dimensional superimposition analysis results by using the independent t test. The 2-way ANOVA was used to detect the effect of each variable (group and site) (α=.05). RESULTS: The VITA SUPRINITY crowns showed statistically higher marginal discrepancy values than the CELTRA DUO crowns in both 3-dimensional superimposition analysis and the direct viewing method, and the lingual aspect recorded the highest marginal discrepancy mean value when compared with other aspects. The 3-dimensional superimposition analysis and the direct viewing method were statistically similar (P=.076). The VITA SUPRINTY crowns showed higher internal gap mean values than the CELTRA DUO crowns in both 3-dimensional superimposition analysis and silicone replica techniques. The occlusal space recorded the highest mean value in both groups. Assessment by 3-dimensional superimposition analysis and silicone replica techniques showed statistical difference in internal gap values (P=.04). CONCLUSIONS: CELTRA DUO showed better precision fit values than VITA SUPRINITY. Three-dimensional superimposition analysis is a reliable method of evaluating marginal and internal adaptation.

Three-dimensional misfit between Ti-Base abutments and implants evaluated by replica technique.

OBJECTIVE: An important factor affecting the biomechanical behavior of implant-supported reconstructions is the implant-abutment misfit. This study evaluated the misfit between Ti-Base abutments and implants by means of polyvinyl siloxane replica technique using microcomputed tomography (µCT). METHODOLOGY: Volumetric and linear (central and marginal) gaps of four Ti-base abutments (n=10/group): (i) Odontofix LTDA (OD), (ii) Singular Implants (SING), (iii) EFF Dental Components (EFF), and (iv) Control Group (S.I.N implants) compatible with an implant system (Strong SW, S.I.N Implants) were measured using µCT reconstructed polyvinyl siloxane replicas. RESULTS: The results showed significantly lower volume gap for Control S.I.N (0.67±0.29 mm3) and SING (0.69±0.28 mm3) Ti-base abutments relative to OD (1.42±0.28 mm3) and EFF groups (1.04±0.28 mm3) (p<0.033), without significant difference between them (p=0.936). While gap values were homogenous in the central region, EFF presented a significantly higher marginal gap. Accordingly, the Control S.I.N and Singular Ti-base abutments showed improved volumetric and marginal fit relative to Odontofix and EFF. CONCLUSION: The method of manufacturing abutments influenced the misfit at the implant-abutment interface.

Seeing is believing? When scanning electron microscopy (SEM) meets clinical dentistry: The replica technique.

In restorative dentistry, the in situ replication of intra-oral situations, is based on a non-invasive and non-destructive scanning electron microscopy (SEM) evaluation method. The technique is suitable for investigation restorative materials and dental hard- and soft-tissues, and its interfaces. Surface characteristics, integrity of interfaces (margins), or fracture analysis (chipping, cracks, etc.) with reliable resolution and under high magnification (from ×50 to ×5,000). Overall the current study aims to share detailed and reproducible information about the replica technique. Specific goals are: (a) to describe detailed each step involved in producing a replica of an intra-oral situation, (b) to validate an integrated workflow based on a rational sequence from visual examination, to macrophotography and SEM analysis using the replica technique; (c) to present three clinical cases documented using the technique. A compilation of three clinical situations/cases were analyzed here by means the replica technique showing a wide range of possibilities that can be reached and explored with the described technique. This guidance document will contribute to a more accurate use of the replica technique and help researchers and clinicians to understand and identify issues related to restorative procedures under high magnification.

Utero-placental vascular remodeling during late gestation in Sprague-Dawley rats.

BACKGROUND: Remodeling of the uterine spiral arteries and blood vessels within the placenta allows delivery of nutrients to the growing utero-fetal-placental unit. While abnormal remodeling of these vessels is thought to play an important role in syndromes including intrauterine growth restriction and preeclampsia, there are a lack of studies that have quantified vascular remodeling in normal pregnant rats. Thus, the purpose of this study was to quantify time-dependent remodeling of the utero-placental vasculature during late gestation in normal pregnant rats. METHODS: Timed-pregnant Sprague-Dawley rats were used. Gestational days of 14 and 19 were chosen because this when a large amount of fetal and placental growth occurs. A combined method of perfusion-casting and 3D micro-computed tomography were utilized to construct ex-vivo utero-placental vasculature images. RESULTS: Significant spiral artery remodeling occurred between days 14 and 19. Vessel density shifted away from a distribution of smaller to larger diameters by day 19. Total spiral artery area and average diameter were increased by day 19. Moreover, branching and tortuosity of the spiral arteries were greater by day 19. In rodents, spiral arteries feed into the central canal vessels that funnel to sites of exchange. Canal vessel area and diameter were increased by day 19. CONCLUSIONS: Our study supports a quantitative method to examine the placental vasculature showing that significant vascular remodeling occurs during late gestation in the utero-placental-fetal unit of the normal pregnant rat. This method may serve as a tool to investigate fundamental pathophysiological mechanisms underlying placental-related diseases in rat models.

Evaluation of gap formation at the composite resin-tooth interface after using universal adhesives: In vitro SEM study using the replica technique.

The aim of this study was to evaluate gap formation after using two universal adhesives, Peak Universal Bond (P), which contains chlorhexidine and Adhese Universal (A), which contains 10-MDP monomer, and to compare them with two gold standard adhesives. The adhesives were tested in different etching modes, etch-and-rinse (ER) or self-etch (SE), and under thermomechanical loading (TML). Two identical Class V cavities were prepared in each of 30 human third molar teeth, and resin-composite restorations were made. Before and after TML, replicas of the restorations were prepared. Gap formation and their frequency according to the modified classification of Blunck and Zaslansky and the width of the maximum marginal gap (MG) were separately evaluated in enamel and dentin. Gap frequency did not differ significantly only in the enamel before TML, despite the use of different adhesives or etching modes. At both timepoints, the highest MG values were obtained with the Peak Universal Bond self-etch (PSE) group in enamel (6.2 µm before TML, 12.2 µm after TML) and the Peak Universal Bond etch-and-rinse (PER) group in dentine (21.3 µm before TML, 35.5 µm after TML). After TML, there was a significant increase of gap frequency for Adhese universal self-etch (ASE) group and MG values for PER, PSE, ASE groups at the resin-enamel interface, and gap frequency and MG values for all groups at the resin-dentin interface. Universal adhesive with 10-MDP monomer have beneficial effect on the resin-dentin interface, while chlorhexidine may reduce the resistance of the universal adhesive system to oral cavity conditions.

Influence of speed sintering on the fit and fracture strength of 3-unit monolithic zirconia fixed partial dentures.

STATEMENT OF PROBLEM: Speed sintering has been introduced to enable single-visit monolithic zirconia prostheses. However, the fit and fracture load of zirconia 3-unit monolithic fixed partial dentures (FPDs) after speed sintering are unknown. PURPOSE: The purpose of this in vitro study was to test the properties of zirconia 3-unit monolithic FPDs after speed sintering and to compare the properties with conventional sintering. MATERIAL AND METHODS: A calibrated operator digitized an in vitro model with a complete coverage preparation of a maxillary right second premolar and second molar (n=12) by using the CEREC AC Omnicam (Dentsply Sirona) scanner. Twelve zirconia FPDs were designed (CEREC SW 4.1.1), and for each data set (n=12), 1 FPD was designed and milled 4 times (MCXL Premium; CEREC Zirconia; Dentsply Sirona), resulting in 4 identical monolithic FPDs (N=48). The FPDs were divided into 2 groups according to the sintering procedure (n=24): speed sintering (group S) by using the SpeedFire (Dentsply Sirona) and the conventional sintering (group C) by using the inFire HTC speed (Dentsply Sirona). All the FPDs were glazed by using glaze-spray and fired according to the sintering group. The SpeedFire (Dentsply Sirona) was used for group S, and the VACUMAT 6000M (VITA Zahnfabrik) was used for group C. The fit of the FPDs was evaluated with the replica technique by using polyvinyl siloxane and analyzed according to the measurement areas: marginal gap, chamfer area, axial wall, and occlusal area. Subsequently, groups S and C were further subdivided, and 12 specimens per group underwent artificial aging by thermomechanical loading in a mastication machine (50 N for 1.2×106 times at a frequency of 1.7 Hz and a thermal change in distilled water from 5 °C to 50 °C every 120 seconds), resulting in additional subgroups: group SA and group CA. For all the FPDs (groups S, C, SA, and CA), a fracture load measurement was conducted. The Kolmogorov-Smirnov test was used to examine the values of the fit and fracture load for normal distribution. The Mann-Whitney U test for the fit and a 2-way ANOVA for the fracture load were used to detect the differences among the groups (α=.05). RESULTS: Group S showed a better marginal (P=.018) and occlusal (P<.001) fit than group C. For the fracture load values, no significant difference was found because of the sintering procedure (P=.070) or the interaction of the sintering procedure and artificial aging (P=.484). Artificial aging showed an impact (P=.024) with significantly lower values after aging. CONCLUSIONS: Speed-sintered FPDs had equal and better values for the fit and fracture load than conventional sintering.

Three-dimensional misfit between Ti-Base abutments and implants evaluated by replica technique

Abstract An important factor affecting the biomechanical behavior of implant-supported reconstructions is the implant-abutment misfit. Objective: This study evaluated the misfit between Ti-Base abutments and implants by means of polyvinyl siloxane replica technique using microcomputed tomography (μCT). Methodology: Volumetric and linear (central and marginal) gaps of four Ti-base abutments (n=10/group): (i) Odontofix LTDA (OD), (ii) Singular Implants (SING), (iii) EFF Dental Components (EFF), and (iv) Control Group (S.I.N implants) compatible with an implant system (Strong SW, S.I.N Implants) were measured using μCT reconstructed polyvinyl siloxane replicas. Results: The results showed significantly lower volume gap for Control S.I.N (0.67±0.29 mm3) and SING (0.69±0.28 mm3) Ti-base abutments relative to OD (1.42±0.28 mm3) and EFF groups (1.04±0.28 mm3) (p<0.033), without significant difference between them (p=0.936). While gap values were homogenous in the central region, EFF presented a significantly higher marginal gap. Accordingly, the Control S.I.N and Singular Ti-base abutments showed improved volumetric and marginal fit relative to Odontofix and EFF. Conclusion: The method of manufacturing abutments influenced the misfit at the implant-abutment interface.

Sequential Replicas: Method for In Vivo Imaging of Plant Organ Surfaces that Undergo Deformation.

Complex geometry of plant organs and various types of organ surface deformation, including growth or hygroscopic movements, can be analyzed using sequential replica method. It enables obtaining a time-lapse series of high resolution images visualizing details of the examined surface and provides data sufficient for detailed computation of parameters characterizing surface deformation and geometry. Series of molds, made in dental polymer, representing the examined surface are used to obtain casts in epoxy resin or nail polish replicas, which are ready for microscopic examination, while the structure itself remains intact. Images obtained from the epoxy casts in scanning electron microscopy can be further used for 3D reconstruction and computation of local geometry. The sequential replica method is a universal method and can be applied to image complex shapes of a range of structures, like meristems, flowers, leaves, scarious bracts, or trichomes. Different plant species growing in various conditions can be studied.

3 D printed replica of the human temporal bone intended for teaching gross anatomy.

The anatomy of the human temporal bone is complex and, therefore, poses unique challenges for students. Furthermore, temporal bones are frequently damaged from handling in educational settings due to their inherent fragility. This report details the production of a durable physical replica of the adult human temporal bone, manufactured using 3D printing technology. The physical replica was printed from a highly accurate virtual 3D model generated from CT scans of an isolated temporal bone. Both the virtual and physical 3D models accurately reproduced the surface anatomy of the temporal bone. Therefore, virtual and physical 3D models of the temporal bone can be used for educational purposes in order to supplant the use of damaged or otherwise fragile human temporal bones.

Comparison of marginal and internal discrepancies of zirconia crowns fabricated by various digital scan methods / 대한치과재료학회지

In this study, marginal and internal discrepancies of zirconia crowns fabricated with the CAD/CAM (computer aided design

Comparative evaluation of marginal and internal fit of metal copings fabricated by various CAD/CAM methods / 대한치과보철학회지

PURPOSE: The purpose of the present study was to compare the accuracy of four different metal copings fabricated by CAD/CAM technology and to evaluate clinical effectiveness. MATERIALS AND METHODS: Composite resin tooth of the maxillary central incisor was prepared for a metal ceramic crown and duplicated metal die was fabricated. Then scan the metal die for 12 times to obtain STL files using a confocal microscopy type oral scanner. Metal copings with a thickness of 0.5 mm and a cement space of 50 µm were designed on a CAD program. The Co-Cr metal copings were fabricated by the following four methods: Wax pattern milling & Casting (WM), Resin pattern 3D Printing & casting (RP), Milling & Sintering (MS), Selective laser melting (SLM). Silicone replica technique was used to measure marginal and internal discrepancies. The data was statistically analyzed with One-way analysis of variance and appropriate post hoc test (Scheffe test) (α=.05). RESULTS: Mean marginal discrepancy was significantly smaller in the Group WM (27.66 ± 9.85 µm) and Group MS (28.88 ± 10.13 µm) than in the Group RP (38.09 ± 11.14 µm). Mean cervical discrepancy was significantly smaller in the Group MS than in the Group RP. Mean axial discrepancy was significantly smaller in the Group WM and Group MS then in the Group RP and Group SLM. Mean incisal discrepancies was significantly smaller in the Group RP than in all other groups. CONCLUSION: The marginal and axial discrepancies of the Co-Cr coping fabricated by the Wax pattern milling and Milling/Sintering method were better than those of the other groups. The marginal, cervical and axial fit of Co-Cr copings in all groups are within a clinically acceptable range.

Evaluation of adaptation of ceramic inlays using optical coherence tomography and replica technique.

Optical coherence tomography (OCT) has generally been used as a nondestructive technique to evaluate integrities of composite restorations. We investigated marginal and internal adaptations of ceramic inlay restorations with OCT and compared them to results with the silicone replica technique. Round-shaped class I cavities were prepared on 16 human maxillary first premolar teeth. Ceramic inlays were fabricated. Silicone replicas from inlays were obtained and sectioned to measure marginal and internal adaptations with a stereomicroscope (Leica Dfc 295, Bensheim, Germany). Inlays were cemented on respective teeth. Marginal and internal adaptations were then measured with the OCT system (Thorlabs, New Jersey, USA) in 200- µm intervals. Replica and OCT measurements were compared with independent samples t-tests. A paired t-test was used to evaluate the marginal and internal adaptations of each group (p < 0.05). Marginal and internal adaptations were 100.97 ± 31.36 and 113.94 ± 39.75 µm, respectively, using the replica technique and 28.97 ± 17.86 and 97.87 ± 21.83 µm, respectively, using OCT. The differences between the techniques were significant (p = 0.00 and p = 0.01, respectively). On evaluation within the groups, internal adaptation values were found to be significantly higher than the marginal adaptation values for the replica technique (p = 0.00) and OCT (p = 0.00). Therefore, the replica and OCT techniques showed different results, with higher values of marginal and internal adaptation found with the replica technique. Marginal and internal adaptation values of ceramic inlays, whether measured by replica or OCT techniques, were within clinically acceptable limits.

Reliability of light microscopy and a computer-assisted replica measurement technique for evaluating the fit of dental copings.

The aim of this in vitro study was to assess the reliability of two measurement systems for evaluating the marginal and internal fit of dental copings. Sixteen CAD/CAM titanium copings were produced for a prepared maxillary canine. To modify the CAD surface model using different parameters (data density; enlargement in different directions), varying fit was created. Five light-body silicone replicas representing the gap between the canine and the coping were made for each coping and for each measurement method: (1) light microscopy measurements (LMMs); and (2) computer-assisted measurements (CASMs) using an optical digitizing system. Two investigators independently measured the marginal and internal fit using both methods. The inter-rater reliability [intraclass correlation coefficient (ICC)] and agreement [Bland-Altman (bias) analyses]: mean of the differences (bias) between two measurements [the closer to zero the mean (bias) is, the higher the agreement between the two measurements] were calculated for several measurement points (marginal-distal, marginal-buccal, axial-buccal, incisal). For the LMM technique, one investigator repeated the measurements to determine repeatability (intra-rater reliability and agreement). For inter-rater reliability, the ICC was 0.848-0.998 for LMMs and 0.945-0.999 for CASMs, depending on the measurement point. Bland-Altman bias was -15.7 to 3.5 µm for LMMs and -3.0 to 1.9 µm for CASMs. For LMMs, the marginal-distal and marginal-buccal measurement points showed the lowest ICC (0.848/0.978) and the highest bias (-15.7 µm/-7.6 µm). With the intra-rater reliability and agreement (repeatability) for LMMs, the ICC was 0.970-0.998 and bias was -1.3 to 2.3 µm. LMMs showed lower interrater reliability and agreement at the marginal measurement points than CASMs, which indicates a more subjective influence with LMMs at these measurement points. The values, however, were still clinically acceptable. LMMs showed very high intra-rater reliability and agreement for all measurement points, indicating high repeatability.

Marginal and internal fit of pressed lithium disilicate inlays fabricated with milling, 3D printing, and conventional technologies.

STATEMENT OF PROBLEM: The subtractive and additive computer-aided design and computer-aided manufacturing (CAD-CAM) of lithium disilicate partial coverage restorations is poorly documented. PURPOSE: The purpose of this in vitro study was to compare the marginal and internal fit accuracy of lithium disilicate glass-ceramic inlays fabricated with conventional, milled, and 3-dimensional (3D) printed wax patterns. MATERIAL AND METHODS: A dentoform mandibular first molar was prepared for a mesio-occlusal ceramic inlay. Five groups of 15 inlays were obtained through conventional impression and manual wax pattern (group CICW); conventional impression, laboratory scanning of the stone die, CAD-CAM milled wax blanks (group CIDW) or 3D printed wax patterns (group CI3DW); and scanning of the master preparation with intraoral scanner and CAD-CAM milled (group DSDW) or 3D printed wax patterns (group DS3DW). The same design was used to produce the wax patterns in the last 4 groups. The replica technique was used to measure marginal and internal adaptation by using stereomicroscopy. Mixed-model ANOVA was used to assess differences according to the groups and discrepancy location (α=.05). RESULTS: Group DSDW showed the smallest marginal discrepancy (24.3 µm) compared with those of groups CICW (45.1 µm), CIDW (33.7 µm), CI3DW (39.8 µm), and DS3DW (39.7 µm) (P<.001). No statistically significant differences were detected among groups CICW, CIDW, CI3DW, and DS3DW relative to the marginal discrepancy. The internal discrepancy was significantly larger than the marginal discrepancy within all groups (P<.001). CONCLUSIONS: Lithium disilicate glass-ceramic inlays produced from digital scans and subtractive milling of wax patterns resulted in better marginal and internal fit accuracy than either conventional impression/fabrication or additive 3D manufacturing. Three-dimensional printed wax patterns yielded fit values similar to those of the conventionally waxed inlays.

Evaluation of the marginal fit of CAD-CAM zirconia copings: Comparison of 2D and 3D measurement methods.

PURPOSE: The purpose of this in vitro study was to compare the marginal fit of zirconia copings by using 2 different measurement methods: a triple optical scan method and a silicone replica method. MATERIAL AND METHODS: Sixty zirconia copings fabricated by computer-aided design and computer-aided manufacture (CAD-CAM) systems were studied for the marginal fit. For the replica method, the thickness of the light-body silicone layer of the discrepancy was assessed using light microscopy and image analysis software. The triple-scan optical method was performed to obtain a digital three-dimensional map of the marginal fit and analyzed marginal fit measurement values. For each method, the reliability of the measurement was tested, and a nonparametric analysis was then performed to compare the marginal fit values as measured by the 2 evaluation methods (α=.05). RESULTS: Intraclass correlation coefficients and repeatability coefficients revealed good repeatability for both of the evaluation methods. However, the triple-scan method produced a smaller marginal fit than the replica method (P<.001) for the entire group studied. CONCLUSIONS: Although both methods showed good repeatability, the triple-scan method was more reliable.

Evaluation of adaptation of ceramic inlays using optical coherence tomography and replica technique

Abstract Optical coherence tomography (OCT) has generally been used as a nondestructive technique to evaluate integrities of composite restorations. We investigated marginal and internal adaptations of ceramic inlay restorations with OCT and compared them to results with the silicone replica technique. Round-shaped class I cavities were prepared on 16 human maxillary first premolar teeth. Ceramic inlays were fabricated. Silicone replicas from inlays were obtained and sectioned to measure marginal and internal adaptations with a stereomicroscope (Leica Dfc 295, Bensheim, Germany). Inlays were cemented on respective teeth. Marginal and internal adaptations were then measured with the OCT system (Thorlabs, New Jersey, USA) in 200- μm intervals. Replica and OCT measurements were compared with independent samples t-tests. A paired t-test was used to evaluate the marginal and internal adaptations of each group (p < 0.05). Marginal and internal adaptations were 100.97 ± 31.36 and 113.94 ± 39.75 μm, respectively, using the replica technique and 28.97 ± 17.86 and 97.87 ± 21.83 μm, respectively, using OCT. The differences between the techniques were significant (p = 0.00 and p = 0.01, respectively). On evaluation within the groups, internal adaptation values were found to be significantly higher than the marginal adaptation values for the replica technique (p = 0.00) and OCT (p = 0.00). Therefore, the replica and OCT techniques showed different results, with higher values of marginal and internal adaptation found with the replica technique. Marginal and internal adaptation values of ceramic inlays, whether measured by replica or OCT techniques, were within clinically acceptable limits.

Reliability of light microscopy and a computer-assisted replica measurement technique for evaluating the fit of dental copings

Abstract The aim of this in vitro study was to assess the reliability of two measurement systems for evaluating the marginal and internal fit of dental copings. Material and Methods: Sixteen CAD/CAM titanium copings were produced for a prepared maxillary canine. To modify the CAD surface model using different parameters (data density; enlargement in different directions), varying fit was created. Five light-body silicone replicas representing the gap between the canine and the coping were made for each coping and for each measurement method: (1) light microscopy measurements (LMMs); and (2) computer-assisted measurements (CASMs) using an optical digitizing system. Two investigators independently measured the marginal and internal fit using both methods. The inter-rater reliability [intraclass correlation coefficient (ICC)] and agreement [Bland-Altman (bias) analyses]: mean of the differences (bias) between two measurements [the closer to zero the mean (bias) is, the higher the agreement between the two measurements] were calculated for several measurement points (marginal-distal, marginal-buccal, axial-buccal, incisal). For the LMM technique, one investigator repeated the measurements to determine repeatability (intra-rater reliability and agreement). Results: For inter-rater reliability, the ICC was 0.848-0.998 for LMMs and 0.945-0.999 for CASMs, depending on the measurement point. Bland-Altman bias was −15.7 to 3.5 μm for LMMs and −3.0 to 1.9 μm for CASMs. For LMMs, the marginal-distal and marginal-buccal measurement points showed the lowest ICC (0.848/0.978) and the highest bias (-15.7 μm/-7.6 μm). With the intra-rater reliability and agreement (repeatability) for LMMs, the ICC was 0.970-0.998 and bias was −1.3 to 2.3 μm. Conclusion: LMMs showed lower interrater reliability and agreement at the marginal measurement points than CASMs, which indicates a more subjective influence with LMMs at these measurement points. The values, however, were still clinically acceptable. LMMs showed very high intra-rater reliability and agreement for all measurement points, indicating high repeatability.

Electrically conductive synthetic vocal fold replicas for voice production research.

A method of fabricating electrically conductive synthetic vocal fold replicas and monitoring their vibration via resistance measurement is presented. Normally non-conductive silicone replicas were coated with conductive graphite and subjected to long-term vibration tests. Synchronized resistance and imaging data using hemilarynx and full larynx configurations showed an inverse correlation between replica contact area and resistance during vibration, similar to clinical electroglottography (EGG) used to estimate vocal fold contact area. This method has potential for long-term replica vibration monitoring and studying basic physical relationships between resistance and contact area in vocal folds and vocal fold replicas.

Variability in coronary artery anatomy affects consistency of cardiac damage after myocardial infarction in mice.

Low reliability and reproducibility in heart failure models are well established. The purpose of the present study is to explore factors that affect model consistency of myocardial infarction (MI) in mice. MI was induced by left coronary artery (LCA) ligation. The coronary artery was casted with resin and visualized with fluorescent imaging ex vivo. LCA characteristics and MI size were analyzed individually in each animal, and MI size was correlated with left ventricular (LV) function by echocardiography. Coronary anatomy varies widely in mice, posing challenges for surgical ligation and resulting in inconsistent MI size postligation. The length of coronary arterial trunk, level of bifurcation, number of branches, and territory supplied by these branches are unique in each animal. When the main LCA trunk is ligated, this results in a large MI, but when a single branch is ligated, MI size is variable due to differing levels of LCA ligation and area supplied by the branches. During the ligation procedure, nearly 40% of LCAs are not grossly visible to the surgeon. In these situations, the surgeon blindly sutures a wider and deeper area of tissue in an attempt to catch the LCA. Paradoxically, these situations have greater odds of resulting in smaller MIs. In conclusion, variation in MI size and LV function after LCA ligation in mice is difficult to avoid. Anatomic diversity of the LCA in mice leads to inconsistency in MI size and functional parameters, and this is independent of potential technical modifications made by the operator.NEW & NOTEWORTHY In the present study, we demonstrate that left coronary artery diversity in mice is one of the primary causes of variable myocardial infarction size and cardiac functional parameters in the left coronary artery ligation model. Recognition of anatomic diversity is essential to improve reliability and reproducibility in heart failure research.

Architecture of the rat nephron-arterial network: analysis with micro-computed tomography.

Among solid organs, the kidney's vascular network stands out, because each nephron has two distinct capillary structures in series and because tubuloglomerular feedback, one of the mechanisms responsible for blood flow autoregulation, is specific to renal tubules. Tubuloglomerular feedback and the myogenic mechanism, acting jointly, autoregulate single-nephron blood flow. Each generates a self-sustained periodic oscillation and an oscillating electrical signal that propagates upstream along arterioles. Similar electrical signals from other nephrons interact, allowing nephron synchronization. Experimental measurements show synchronization over fields of a few nephrons; simulations based on a simplified network structure that could obscure complex interactions predict more widespread synchronization. To permit more realistic simulations, we made a cast of blood vessels in a rat kidney, performed micro-computed tomography at 2.5-µm resolution, and recorded three-dimensional coordinates of arteries, afferent arterioles, and glomeruli. Nonterminal branches of arcuate arteries form treelike structures requiring two to six bifurcations to reach terminal branches at the tree tops. Terminal arterial structures were either paired branches at the tops of the arterial trees, from which 52.6% of all afferent arterioles originated, or unpaired arteries not at the tree tops, yielding the other 22.9%; the other 24.5% originated directly from nonterminal arteries. Afferent arterioles near the corticomedullary boundary were longer than those farther away, suggesting that juxtamedullary nephrons have longer afferent arterioles. The distance separating origins of pairs of afferent arterioles varied randomly. The results suggest an irregular-network tree structure with vascular nodes, where arteriolar activity and local blood pressure interact.