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.

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.

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.

Simulated Wound Assessment Using Digital Planimetry versus Three-Dimensional Cameras: Implications for Clinical Assessment.

BACKGROUND: Clinical management of wounds can benefit from objective measures of response to treatment. Wound surface area and volume are objective measures of wound healing. Using a synthetic wound model, we compare the accuracy and reproducibility of 2 commercially available 3-dimensional (3D) cameras against planimetry and water displacement. METHODS: Twelve ulcers of various sizes and colors were reproduced in modeling clay and cured. Five naive observers used digital planimetry, water displacement, Eykona camera (Fuel 3D, UK), and Silhouette camera (ARANZ, New Zealand) to measure the wounds. RESULTS: When compared with traditional planimetry, wound surface area measurement with Eykona and Silhouette tended to underestimate wounds by 1.7% and 3.7%, respectively. Spearman correlation coefficients were 0.94 (Eykona) and 0.92 (Silhouette). Intraclass correlations for planimetry and the 2 cameras were all 1. Eykona and Silhouette tended to underestimate wound volumes when compared with water displacement by 58% and 23%, respectively. Spearman correlation coefficients were 0.92 (Eykona) and 0.72 (Silhouette). Intraclass correlations for water displacement and the two cameras were all 1. DISCUSSION: Serial accurate objective area measurements are feasible as part of ongoing clinical assessment of wounds. 3D cameras are reliable but have not shown superior accuracy to manual planimetry, and financial concerns and IT integration may limit general clinical usage. Volume measurements of wounds are practicable as part of clinical care.

Impact of Yttrium-90 Microsphere Density, Flow Dynamics, and Administration Technique on Spatial Distribution: Analysis Using an In Vitro Model.

PURPOSE: To investigate material density, flow, and viscosity effects on microsphere distribution within an in vitro model designed to simulate hepatic arteries. MATERIALS AND METHODS: A vascular flow model was used to compare distribution of glass and resin surrogates in a clinically derived flow range (60-120 mL/min). Blood-mimicking fluid (BMF) composed of glycerol and water (20%-50% vol/vol) was used to simulate a range of blood viscosities. Microsphere distribution was quantified gravimetrically, and injectate solution was dyed to enable quantification by UV spectrophotometry. Microsphere injection rate (5-30 mL/min) and the influence of contrast agent dilution of injection solution (0%-60% vol/vol) were also investigated. RESULTS: No significant differences in behavior were observed between the glass and resin surrogate materials under any tested flow conditions (P = .182; n = 144 injections). Microspheres tend to align more consistently with the saline injection solution (r2 = 0.5712; n = 144) compared with total BMF flow distribution (r2 = 0.0104; n = 144). The most predictable injectate distribution (ie, greatest alignment with BMF flow, < 5% variation) was demonstrated with > 10-mL/min injection rates of pure saline solution, although < 20% variation with glass microsphere distribution was observed with injection solution containing as much as 30% contrast medium when injected at > 20 mL/min. CONCLUSIONS: Glass and resin yttrium-90 surrogates demonstrated similar distribution in a range of clinically relevant flow conditions, suggesting that microsphere density does not have a significant influence on microsphere distribution. Injection parameters that enhanced the mixing of the spheres with the BMF resulted in the most predictable distribution.

Determining the morphometry and variations of the confluens sinuum and related structures via a silicone painting technique on autopsy patients.

In this study, we aimed to investigate the morphometric and morphologic structures of the confluens sinuum (CS) and related structures with a silicone painting technique. We studied 30 cadavers. Twelve of them were washed with alcohol and filled with a silicone painting technique via the vena jugularis interna, internal carotid artery, and vertebral artery. The other 18 were autopsied postmortem. The CS and related structures were dissected under microscope. Their anatomy was investigated, and variations were noted. The diameters of the sinus sagittalis superior (SSS), CS, occipital sinus (OS), sinus rectus (SR), and bilateral transverse sinus (TS), and the angle between SSS and SR were measured. The mean diameters were 11.7 mm for SSS, 22.3 mm for CS, 5.25 mm for OS, 7.5 mm for SR, and 9.7 (right) and 9.1 mm (left) for TS. The angle between the SR and SSS was 58°. There was no difference in the bilateral venous structures that drained to the SSS and TS. There was an extra drainage to the CS from the left side in 4 cases. The right TS was located superiorly in 7 cases compared with the left TS, and this process was correlated with the type of CS. A septum in the SSS was detected in 2 cases. In addition, we encountered an OS in 80% of the cases. We conclude that the septum inside the CS affects the dominancy of the TS, the angle between the SSS and SR, and the other venous variations.

Anterior communicating artery aneurysm surgery: which is the most appropriate head position?

Head positioning and the degree of rotation for anterior communicating artery aneurysm surgery is controversial. With this anatomic study, we aimed to give a broad description of head positioning for various aneurysm dome projections. In addition, with the use of a corrosion-cast technique, a three-dimensional arterial tree was demonstrated, an anterior communicating artery region aneurysm model was prepared, and pictures were taken at various angles. According to our observations, 30-degree head rotation was found to be the most suitable position for the anterior and superior projected aneurysms. For posterior projection, aneurysm neck was best viewed with 15-degree head rotation. Aneurysms projecting inferiorly necessitated the greatest rotation at 45 degrees. Each aneurysm dome projection of the anterior communicating artery aneurysm should be individually considered, and the head position should be adjusted accordingly. The use of appropriate head positions during surgery will prevent the development of postoperative ischemic complications and will increase the success of surgery by preventing unnecessary tissue manipulation.

Avaliação do assentamento de coroas totais à base de dissilicato de lítio produzidas por três diferentes fluxos de trabalho: convencional, digital ou parcialmente digital / Fit of lithium dissilicate crowns made by three workflows: conventional, partially digital and totally digital

Este estudo avaliou os assentamentos marginal e interno em 4 áreas predeterminadas de coroas totais à base de dissilicato de lítio produzidas por 3 fluxos de trabalho distintos. Um modelo-mestre de titânio com um preparo para coroa total em um molar foi confeccionado. Foram produzidas 36 coroas totais à base de dissilicato de lítio. As coroas foram divididas em 3 grupos, de acordo com o fluxo de trabalho: Totalmente Convencional (TC): moldagem do modelo-mestre com polieter, vazagem com gesso tipo IV e confecção de 12 coroas (IPS e.max PRESS) no laboratório de prótese; Totalmente Digital (TD): escaneamento do modelo-mestre com a Bluecam™ e usinagem de 12 coroas totais (IPS e.max CAD™) no CEREC 3™; e Parcialmente Digital (PD): moldagem do modelo-mestre com polieter, vazagem com gesso tipo IV, escaneamento do modelo de gesso com a Bluecam™ e usinagem de 12 coroas totais (IPS e.max CAD™) no CEREC 3™. Para a avaliação do assentamento foi utilizada a técnica da réplica, onde a base leve do silicone de adição simulou um cimento. Duas réplicas por coroa total foram confeccionadas, gerando imagens de interfaces vestíbulo-palatal e mesio-distal sob magnificação de 50x. Quatro áreas foram definidas para a avaliação: Abertura Marginal (AM); Chanfro (CH); Parede Axial (PA); e Parede Oclusal (PO). Um software realizou a medição dos valores em toda a área demarcada, gerando aproximadamente 6.000 pontos de avaliação por interface. Os resultados foram estatisticamente analisados por meio dos testes One-Way-Anova e Scheafer's Post-Hoc, com grau de significância estabelecido em 5%. Todas os grupos testados no estudo apresentaram médias de valores clinicamente aceitáveis para os assentamentos marginal e interno. Não houve diferença significativa em AM, CH e PO entre os três grupos testados. Em PA, o grupo TC apresentou valores significativamente maiores do que PD e TD (p = 0,001). Os diferentes fluxos de trabalho, convencional ou digitais, aplicados neste estudo, foram capazes de prover adequados assentamentos marginal e interno, dentro dos valores clínicos estabelecidos para coroas totais à base de porcelana.

The aim of this study was to evaluate the marginal and internal fit of porcelain indirect restorations produced by three distinct workflows in four pre-determined interface areas. A titanium master model - simulating a full crown molar preparation - was built to this study. 36 lithium dissilicate full crowns coverage were produced. The restorations were divided in 3 groups, according to the workflow: Totally Conventional (TC), where a polieter impression of the master model was poured with type IV gypsum, and 12 full crown coverages (IPS e.max PRESS™) were produced in the dental technician; Totally Digital (TD), where the master model was scanned with the Bluecam™ and 12 full crown coverages (IPS e.max CAD™) were milled in the CEREC 3™; Partially Digital (PD), where a polieter impression of the master model was poured with type IV gypsum, with the Bluecam™ scanning the working model and the 12 full crown coverages (IPS e.max CAD™) being milled by the CEREC 3™. The replica technique, where the light body silicone simulate the cement, was used to evaluate the fit of the crowns. Two cross sectioned replicas per crown were obtained, generating images of the bucco-palatal and mesio-distal interfaces under 50x magnification. Four interface areas were choosen to the evaluation: Marginal Opening (AM); Chamfer (CH), Axial Wall (PA); and Occlusal Wall (PO). The hole interface area of each image was evaluated, generating approximately 6.000 points to be rated per interface. Results were statistical analyzed with one-way-Anova and Scheafer's post hoc with a 5% level of significance. All the 3 tested groups showed clinically acceptable mean values for marginal and internal fit. For the areas AM, CH and PO, similar results were found between the 3 groups. For the PA area, TC group showed significantely higher values than PD and TD groups (p = 0,001). The different workflows, conventional or digitals, used in this study were proven capable to present elegible marginal and internal fit, based on the accepted current values for porcelain full coverage crowns.

Evaluation of root-end preparation with a new ultrasonic tip.

INTRODUCTION: This study was conducted to evaluate the effect of a new ultrasonic tip (Jetip) for root-end preparation. METHODS: A total of 80 single-rooted teeth were endodontically treated, and the apical 3 mm of the root apex was resected. Teeth were randomly distributed into 2 experimental groups according to the ultrasonic tips used to prepare the root-end cavity. Epoxy resin replicas of root-end surfaces after root-end resection were obtained. A root-end cavity was then prepared with an ultrasonic tip, either Jetip or AS3D. Replicas of the apices were fabricated after the retropreparations, and they were processed for analysis by scanning electron microscopy (SEM) to evaluate the presence of microcracks and the quality of the root-end preparation. The morphologic characteristics of the ultrasonic tip were also assessed by SEM. The time required for root-end preparation was recorded. RESULTS: There were no statistically significant differences between the Jetip and AS3D groups in the mean time for the root-end preparation, the incidence of microcracks, or the quality of the root-end preparation (P > .05). SEM analysis showed that Jetip exhibited smoothed microprojections after the root preparations, whereas the loss of diamond particles was observed in AS3D. CONCLUSIONS: Both Jetip and AS3D provided rapid and regular root-end preparations. The cutting efficiencies of both Jetip and AS3D decreased with the number of times the tips were used. The Jetip showed smooth microprojections after root-end preparation, whereas the AS3D tip exhibited the loss of diamond particles.

A retrospective case series illustrating a possible association between a widened hilum and sialolith formation in the submandibular gland.

OBJECTIVE: The purpose of this study was to explore any association between anatomical variances in the ductal system and sialolith formation using sialoendoscopy and acrylic resin replication of the ductal system. METHODS: A retrospective study of 372 submandibular gland sialoendoscopies was performed to review the findings of the submandibular gland duct anatomy. Using sialoendoscopy and replicated casts, a high rate of hilar widening was noted in patients with submandibular sialolithiasis. RESULTS: Sialolithiasis was detected in 326 of the patients who presented with obstructive symptoms. Around 67% (285/426) of the stones were located in the distal third of the ducts or at the hilum of the submandibular gland. During the sialoendoscopic procedure, the anatomy of the ductal system was examined and 285/326 (87.4%) of the hilums were noted to be widened like a basin. The anatomy of the duct from the replicated casts demonstrated a treelike structure and the basin-like widening of the hilum was found in all the excised submandibular glands. CONCLUSION: Using sialoendoscopy, a high number of patients presenting with sialolithiasis in the submandibular gland seem to have an anatomical variance in the hilar region. The reproduced ductal system from excised glands also demonstrated this abnormal widening of the hilum. Although further studies need to be performed, we try and explain why there is such a high prevalence of hilar widening in patients with submandibular sialolithiasis.

Different sizes of centrilobular ground-glass opacities in chest high-resolution computed tomography of patients with pulmonary veno-occlusive disease and patients with pulmonary capillary hemangiomatosis.

BACKGROUND: Centrilobular ground-glass opacity (GGO) is one of the characteristic findings in chest high-resolution computed tomography (HRCT) of patients with pulmonary veno-occlusive disease (PVOD) and patients with pulmonary capillary hemangiomatosis (PCH). However, clinical differential diagnosis of these two diseases is difficult and has not been established. In order to clarify their differences, we compared the sizes of GGOs in chest HRCT and the sizes of capillary assemblies in pulmonary vascular casts between patients diagnosed pathologically with PVOD and PCH. METHODS: We evaluated chest HRCT images for four patients with idiopathic pulmonary arterial hypertension (IPAH), three patients with PVOD and three patients with PCH, and we evaluated pulmonary vascular casts of lung tissues obtained from those patients at lung transplantation or autopsy. RESULTS: Centrilobular GGOs in chest HRCT were observed in patients with PVOD and patients with PCH but not in patients with IPAH. We measured the longest diameter of the GGOs. The size of centrilobular GGOs was significantly larger in patients with PCH than in patients with PVOD (5.60±1.43 mm versus 2.51±0.79 mm, P<.01). We succeeded in visualization of the 3-dimensional structures of pulmonary capillary vessels obtained from the same patients with PVOD and PCH undergoing lung transplantation or autopsy and measured the diameters of capillary assemblies. The longest diameter of capillary assemblies was also significantly larger in patients with PCH than in patients with PVOD (5.44±1.71 mm versus 3.07±1.07 mm, P<.01). CONCLUSION: Measurement of the sizes of centrilobular GGOs in HRCT is a simple and useful method for clinical differential diagnosis of PVOD and PCH.

Imaging of vascular remodeling after simulated thoracoabdominal aneurysm repair.

OBJECTIVE: A better understanding of the response of the spinal cord blood supply to segmental artery (SA) sacrifice should help minimize the risk of paraplegia after both open and endovascular repair of thoracoabdominal aortic (TAA) aneurysms. METHODS: Twelve female juvenile Yorkshire pigs were randomized into 3 groups and perfused with a barium-latex solution. Pigs in group 1 (control) had infusion without previous intervention. Pigs in group 2 were infused 48 hours after ligation of all SAs (T4-L5) and those in group 3 at 120 hours after ligation. Postmortem computed tomographic scanning of the entire pig enabled overall comparisons and measurement of vessel diameters in the spinal cord circulation. RESULTS: We ligated 14.5 ± 0.8 SAs: all filled retrograde to the ligature. Paraplegia occurred in 38% of operated pigs. A significant increase in the mean diameter of the anterior spinal artery (ASA) was evident after SA sacrifice (P < .0001 for 48 hours and 120 hours). The internal thoracic and intercostal arteries also increased in diameter. Quantitative assessment showed an increase in vessel density 48 hours after ligation of SAs, reflected by an obvious increase in small collateral vessels seen on 3-dimensional reconstructions of computed tomographic scans at 120 hours. CONCLUSIONS: Remodeling of the spinal cord blood supply--including dilatation of the ASA and proliferation of small collateral vessels--is evident at 48 and 120 hours after extensive SA sacrifice. It is likely that exploitation of this process will prove valuable in the quest to eliminate paraplegia after TAA aneurysm repair.

The anatomy of fluid-yielding ducts in breast cancer.

The concept of an intraductal approach to evaluate the breast microenvironment assumes direct access to the cancer-containing duct. Central duct access to the cancer-affected lobe is essential if cytology or cell markers are to be useful indicators of pre-malignant change. Access to the cancer-bearing lobe would be less important if field change effects of malignant change were predominantly supra-lobar. The aim of this study was to determine how often duct lavage fluid drains the breast cancer-affected segment. 58 patients undergoing mastectomy for breast cancer were recruited among which 47 had at least one fluid-yielding duct. Following duct lavage, fluid-yielding ducts were perfused ex vivo with Polyurethane Elastomer (PU4ii) resin. Specimens were sliced sagittally, and the extent of resin perfusion and anatomical relationship to the cancer-affected segment was recorded. Computed tomography (CT) scanning was performed on selected mastectomies before cut-up for a feasibility study of 3D duct reconstruction. The median number of fluid-yielding ducts cannulated per cancer-affected breast was 2 (range 1-4). 35/47 (74%) mastectomy specimens were successfully cannulated for resin perfusion. 29/35 (83%) showed tracing of the cancer-affected duct system, 6/35 resin perfusions traced duct systems unaffected by cancer and 12/35 perfusions extravasated. The proportion of sagittal breast slices perfused by resin was 13-68% (median 43%). Volume rendering CT showed it is feasible to produce a simulated image of the perfused ducts. Duct access to the cancer-containing segment is feasible in the majority of patients. Fluid-yielding ducts proportionately drain a significant volume of the breast. Large symptomatic cancers may cause obstruction with distal collapse. Further quantitative study of breast perfusion CT scans may be helpful for estimating the volume fraction of breast tissue perfused by fluid-yielding ducts. The intraductal approach is a valid concept for biomarker assessment of cancer-containing breast segments.

Cementogenesis examined from the viewpoint of microcirculation.

The purpose of this study was to perform a three-dimensional observation, via microvascular corrosion casts, of the microcirculation system during deposition of cementum after flap surgery and to investigate the permeable structure of the vascular endothelium. Two stages of wound healing after flap surgery were confirmed based on successive vascular changes. The transition between these stages occurred 3 weeks after surgery, at which time new blood vessels disappeared and an early stage of accumulation of new cementum was apparent. Hence, fibrous repair occurred during the first stage, and repair of hard tissue (ie, formation of cementum) occurred during the second stage. These findings suggest that metabolic activity in cementogenesis is low, based on the condition of the blood vessels, and therefore new cementum is not easily formed.

Evaluation of ultrasonic and ErCr:YSGG laser retrograde cavity preparation.

Root end cavity preparation techniques aim to create a clean and properly shaped cavity in a short time. Although the use of ultrasonics has been widely recommended, a laser can also be used. This study evaluated the time required and quality of retrograde cavity preparations using ultrasonics or ErCr:YSGG laser. Thirty single-rooted teeth were instrumented, root filled, submitted to apicectomies, and grouped. Root end cavities were prepared by using the following: group 1 (G1): CVD (6.1107-6) ultrasonic retrotips (CVD-Vale, São José dos Campos, Brazil); group 2 (G2): EMS (DT-060/Berutti) ultrasonic retrotips (EMS, LeSentier, Switzerland); and group 3 (G3): ErCr:YSGG (G6/Waterlase; Biolase Technology, San Clemente, CA) laser tips. The time taken to complete the preparation was recorded. Epoxy resin replicas of the root apices were examined under a scanning electron microscope. The parameters for evaluation were the presence of fractures, and the quality of the preparations. The Waterlase showed the highest mean time for preparation of the root end cavities (p < 0.05), and there was no significant difference between the CVD and EMS groups (p > 0.05). Fractures in the cavosurface angle occurred only in G2. G1 and G2 showed better scores for quality of preparation than G3 (p < 0.05). These results suggest that root end cavities should be prepared by ultrasonic tips.

Marginal adaptation of root-end filling materials: an in vitro study with teeth and replicas.

AIM: The purpose of this investigation was to evaluate the marginal adaptation of five root-end filling materials. METHODS AND MATERIALS: Fifty human single-rooted teeth were resected 3 mm from the apex. Root-end cavities were then prepared using an ultrasonic tip and filled with one of the following materials: silver amalgam without zinc, white MTA-Angelus, white Portland cement (PC), Vitremer, and GC Fuji Ortho LC. The apical portion of the roots was then sectioned to obtain two 1 mm thick transversal sections. Epoxy resin replicas of these apical sections were fabricated for an analysis of marginal adaptation. Scanning electron microscopy (SEM) was used to determine gaps in the adaptation of the root-end filling materials at the interface between them and the dentin. The Kruskal-Wallis test and a multiple comparison test were used for statistical data analysis. The Spearman correlation coefficient was used to determine the correlation between the results found for teeth and replicas. RESULTS: Materials containing calcium oxide (MTA and PC) showed similar results. Resin modified glass ionomer cements (GICs) presented similar variations in marginal adaptation, but Vitremer showed significantly greater marginal adaptation when compared to GC Fuji Ortho LC. CONCLUSION: A positive and significant correlation was observed between marginal adaptation values found in the teeth and their replicas. CLINICAL SIGNIFICANCE: The use of ionomers as root-end filling materials may improve clinical outcomes in periradicular surgery.

Rapid prototyping of compliant human aortic roots for assessment of valved stents.

Adequate in-vitro training in valved stents deployment as well as testing of the latter devices requires compliant real-size models of the human aortic root. The casting methods utilized up to now are multi-step, time consuming and complicated. We pursued a goal of building a flexible 3D model in a single-step procedure. We created a precise 3D CAD model of a human aortic root using previously published anatomical and geometrical data and printed it using a novel rapid prototyping system developed by the Fab@Home project. As a material for 3D fabrication we used common house-hold silicone and afterwards dip-coated several models with dispersion silicone one or two times. To assess the production precision we compared the size of the final product with the CAD model. Compliance of the models was measured and compared with native porcine aortic root. Total fabrication time was 3 h and 20 min. Dip-coating one or two times with dispersion silicone if applied took one or two extra days, respectively. The error in dimensions of non-coated aortic root model compared to the CAD design was <3.0% along X, Y-axes and 4.1% along Z-axis. Compliance of a non-coated model as judged by the changes of radius values in the radial direction by 16.39% is significantly different (P<0.001) from native aortic tissue--23.54% at the pressure of 80-100 mmHg. Rapid prototyping of compliant, life-size anatomical models with the Fab@Home 3D printer is feasible--it is very quick compared to previous casting methods.

The effects of ozone gas application on shear bond strength of orthodontic brackets to enamel.

PURPOSE: To investigate the possibility that ozone may have an adverse effect on the bond strength of orthodontic brackets and to determine the area of residual adhesive on teeth after the debonding of brackets. METHODS: 60 extracted premolars teeth were used in this study. Resin coated APC brackets (3M) were bonded according to the manufacturers' instructions. Bonded teeth were randomly divided into two groups. The teeth in Group 1 were subjected to a 10-second dosage of ozone from the HealOzone unit (Kavo) after etching and to a further 10 seconds of ozone after bonding the brackets using a 5 mm delivery cup. Teeth in Group 2 were used as a control. Debonding was carried out using a testing instrument at a cross-head speed of 1 mm/minute. RESULTS: The Mann-Whitney test revealed no significant differences in shear bond strength between the two groups (P = 0.337). The mean shear bond strength (11.66 MPa) of Group 1 (subjected to ozone) was not significantly different than the mean shear bond strength (10.88 MPa) of Group 2 (not subjected to ozone). A Pearson Chi-square test of the Adhesive Remnant Index (ARI) revealed no significant difference in residual adhesive among the groups tested.

An objective assessment of botulinum toxin A effect on superficial skin texture.

The botulinum toxin A (BTX-A) role on elimination of hyperkinetic wrinkles is consolidated, although relying on subjective methods of assessment. A prospective open-label study was performed on 10 patients to objectively analyze superficial skin texture changes caused by BTX-A in the glabellar area. Skin areas were reproduced by silicon replica technique at baseline, 1 month, and 6 months after treatment. Takahashi's parameters (roughness, anisotropy, microsulcus number, and width) were obtained from scanning electron microscopy (SEM) analysis and compared using the Wilcoxon signed rank test. SEM images showed skin texture changes, and software analysis gave parameters for statistical analysis, allowing an objective evaluation. Statistically significant parameter modifications were evidenced. BTX-A effectiveness in wrinkle treatment was confirmed, and no differences in skin texture parameters from baseline to toxin action end were noted.

Replica exchange with solute tempering: efficiency in large scale systems.

We apply the recently developed replica exchange with solute tempering (REST) to three large solvated peptide systems: an alpha-helix, a beta-hairpin, and a TrpCage, with these peptides defined as the "central group". We find that our original implementation of REST is not always more efficient than the replica exchange method (REM). Specifically, we find that exchanges between folded (F) and unfolded (U) conformations with vastly different structural energies are greatly reduced by the nonappearance of the water self-interaction energy in the replica exchange acceptance probabilities. REST, however, is expected to remain useful for a large class of systems for which the energy gap between the two states is not large, such as weakly bound protein-ligand complexes. Alternatively, a shell of water molecules can be incorporated into the central group, as discussed in the original paper.