Validity and reliability of hallux valgus angle measured on digital photographs

STUDY DESIGN: Controlled laboratory study. OBJECTIVES: To investigate the reliability and concurrent validity of photographic measurements of hallux valgus angle compared to radiographs as the criterion standard. BACKGROUND: Clinical assessment of hallux valgus involves measuring alignment between the first toe and metatarsal on weight-bearing radiographs or visually grading the severity of deformity with categorical scales. Digital photographs offer a noninvasive method of measuring deformity on an exact scale; however, the validity of this technique has not previously been established. METHODS: Thirty-eight subjects (30 female, 8 male) were examined (76 feet, 54 with hallux valgus). Computer software was used to measure hallux valgus angle from digital records of bilateral weight-bearing dorsoplantar foot radiographs and photographs. One examiner measured 76 feet on 2 occasions 2 weeks apart, and a second examiner measured 40 feet on a single occasion. Reliability was investigated by intraclass correlation coefficients and validity by 95% limits of agreement. The Pearson correlation coefficient was also calculated. RESULTS: Intrarater and interrater reliability were very high (intraclass correlation coefficients greater than 0.96) and 95% limits of agreement between photographic and radiographic measurements were acceptable. Measurements from photographs and radiographs were also highly correlated (Pearson r = 0.96). CONCLUSIONS: Digital photographic measurements of hallux valgus angle are reliable and have acceptable validity compared to weight-bearing radiographs. This method provides a convenient and precise tool in assessment of hallux valgus, while avoiding the cost and radiation exposure associated with radiographs.

A split cassette attachment for recording all the reflections on the upper level Weissenberg photographs either as elongated or as contracted spots

A split-cassette arrangement has been incorporated in the Weissenberg camera for recording all reflections on the upper level photographs either as elongated or as contracted spots. This arrangement employs two semicylindrical cassettes which are separated by a horizontal plane. These half-cassettes are translated in opposite directions. A suitable split-cassette attachment has been constructed for the Unicam Weissenberg goniometer S-35 The subject of 'displaced-film' Weissenberg photograph is also discussed.

An improved estimate of leaf area index based on the histogram analysis of hemispherical photographs

Leaf area index (LAI) is a key parameter that affects the surface fluxes of energy, mass, and momentum over vegetated lands, but observational measurements are scarce, especially in remote areas with complex canopy structure. In this paper we present an indirect method to calculate the LAI based on the analyses of histograms of hemispherical photographs. The optimal threshold value (OTV), the gray-level required to separate the background (sky) and the foreground (leaves), was analytically calculated using the entropy crossover method (Sahoo, P.K., Slaaf, D.W., Albert, T.A., 1997. Threshold selection using a minimal histogram entropy difference. Optical Engineering 36(7) 1976-1981). The OTV was used to calculate the LAI using the well-known gap fraction method. This methodology was tested in two different ecosystems, including Amazon forest and pasturelands in Brazil. In general, the error between observed and calculated LAI was similar to 6%. The methodology presented is suitable for the calculation of LAI since it is responsive to sky conditions, automatic, easy to implement, faster than commercially available software, and requires less data storage. (C) 2008 Elsevier B.V. All rights reserved.

Strain Gauge Analysis of the Effect of Porcelain Firing Simulation on the Prosthetic Misfit of Implant-Supported Frameworks

Objectives: This study investigated the effect of porcelain firing on the misfit of implant-supported frameworks and analyzed the influence of preheat treatment on the dimensional alterations.Materials and Methods: Four external-hex cylindrical implants were placed in polyurethane block. Ten frameworks of screw-retained implant-supported prostheses were cast in Pd-Ag using 2 procedures: (1) control group (CG, n = 5): cast in segments and laser welded; and test group (TG, n = 5): cast in segments, preheated, and laser welded. All samples were subjected to firing to simulate porcelain veneering firing. Strain gauges were bonded around the implants, and microstrain values (mu epsilon = 10(-6)epsilon) were recorded after welding (M1), oxidation cycle (M2), and glaze firing (M3). Data were statistically analyzed (2-way analysis of variance, Bonferroni, alpha = 0.05).Results: The microstrain value in the CG at M3 (475.2 mu epsilon) was significantly different from the values observed at M1 (355.6 mu epsilon) and M2 (413.9 mu epsilon). The values at M2 and M3 in the CG were not statistically different. Microstrain values recorded at different moments (M1: 361.6 mu epsilon/M2: 335.3 mu epsilon/M3: 307.2 mu epsilon) did not show significant difference.Conclusions: The framework misfit deteriorates during firing cycles of porcelain veneering. Metal distortion after porcelain veneering could be controlled by preheat treatment. (Implant Dent 2012;21:225-229)

The effect of porcelain thickness and surface liner application on the fracture behavior of a ceramic system

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of multiple firing and silica deposition on the zirconia-porcelain interfacial bond strength

Objectives. To test the hypothesis that multiple firing and silica deposition on the zirconia surface influence the bond strength to porcelain.Materials and methods. Specimens were cut from yttria-stabilized zirconia blocks and sintered. Half of the specimens (group S) were silica coated (physical vapor deposition (PVD)) via reactive magnetron sputtering before porcelain veneering. The remaining specimens (group N) had no treatment before veneering. The contact angle before and after silica deposition was measured. Porcelain was applied on all specimens and submitted to two (N2 and S2) or three firing cycles (N3 and S3). The resulting porcelain-zirconia blocks were sectioned to obtain bar-shaped specimens with 1 mm(2) of cross-sectional area. Specimens were attached to a universal testing machine and tested in tension until fracture. Fractured surfaces were examined using optical microscopy. Data were statistically analyzed using two-way ANOVA, Tukey's test (alpha = 0.05) and Weibull analysis.Results. Specimens submitted to three firing cycles (N3 and S3) showed higher mean bond strength values than specimens fired twice (N2 and S2). Mean contact angle was lower for specimens with silica layer, but it had no effect on bond strength. Most fractures initiated at porcelain-zirconia interface and propagated through the porcelain.Significance. The molecular deposition of silica on the zirconia surface had no influence on bond strength to porcelain, while the number of porcelain firing cycles significantly affected the bond strength of the ceramic system, partially accepting the study hypothesis. Yet, the Weibull modulus values of S groups were significantly greater than the m values of N groups. (C) 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Effects of extreme cooling methods on mechanical properties and shear bond strength of bilayered porcelain/3Y-TZP specimens

Objectives: This study investigated the effect of extreme cooling methods on the flexural strength, reliability and shear bond strength of veneer porcelain for zirconia. Methods: Vita VM9 porcelain was sintered on zirconia bar specimens and cooled by one of the following methods: inside a switched-off furnace (slow), at room temperature (normal) or immediately by compressed air (fast). Three-point flexural strength tests (FS) were performed on specimens with porcelain under tension (PT, n = 30) and zirconia under tension (ZT, n = 30). Shear bond strength tests (SBS, n = 15) were performed on cylindrical blocks of porcelain, which were applied on zirconia plates. Data were submitted to one-way ANOVA and Tukey's post hoc tests (p < 0.05). Weibull analysis was performed on the PT and ZT configurations. Results: One-way ANOVA for the PT configuration was significant, and Tukey's test revealed that fast cooling leads to significantly higher values (p < 0.01) than the other cooling methods. One-way ANOVA for the ZT configuration was not significant (p = 0.06). Weibull analysis showed that normal cooling had slightly higher reliability for both the PT and ZT configurations. Statistical tests showed that slow cooling decreased the SBS value (p < 0.01) and showed less adhesive fracture modes than the other cooling methods. Clinical Significance: Slow cooling seems to affect the veneer resistance and adhesion to the zirconia core; however, the reliability of fast cooling was slightly lower than that of the other methods. © 2013 Elsevier Ltd.

Zirconia-Porcelain Bonding: Effect of Multiple Firings on Microtensile Bond Strength

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of the Layering Technique on Bond Strength and Cohesive Resistance of a Porcelain-Zirconia System

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The effect of thermal cycling on the shear bond strength of porcelain/Ti-6Al-4V interfaces

The aim of the study was to evaluate the effect of thermal cycling on the shear bond strength of the porcelain/Ti-6Al-4V interfaces prepared by two different processing routes and metallic surface conditions. Polished and SiO2 particle abraded Ti-6Al-4V alloy and Triceram bonder porcelain were used to produce the interfaces. Porcelain-to-metal specimens were processed by conventional furnace firing and hot pressing. Thermal cycling was performed in Fusayama's artificial saliva for 5000 cycles between 5 +/- 1 and 60 +/- 2 degrees C. After thermal cycling, shear bond tests were carried out by using a custom-made stainless steel apparatus. The results were analyzed using t-Student test and non-parametric Kruskal-Wallis test (p<0.01). Most of the polished-fired specimens were fractured during thermal cycling; thus, it was not possible to obtain the shear bond strength results for this group. Sandblasted-fired, polished-hot pressed, and sandblasted-hot pressed specimens presented the shear bond strength values of 76.2 +/- 15.9, 52.2 +/- 23.6, and 59.9 +/- 22.0 MPa, respectively. Statistical analysis indicated that thermal cycling affected the polished specimens processed by firing, whereas a significant difference was not observed on the other groups. (C) 2015 Elsevier Ltd. All rights reserved.

The Absence of Atrocity: On Bart Michiels’ "The Course of History" Photographs

This article examines the absence of atrocity in the photographic series The Course of History by the Belgian-born, New York-based photographer Bart Michiels (1964–). It shows, in beautiful, large-format prints, seemingly innocent landscapes and confined views of nature. Only when viewers read the titles of the photographs do they become aware of the violent history of the sites. These turn out to be the fields of fierce European battles such as Verdun, Waterloo and Stalingrad. The present article reviews recent trends towards using place as a motif in contemporary art photography and focuses on the ‘empty’ landscape as a pictorial strategy that opens up a narrative space, one that needs to be completed by the viewer. The absence evoked by the image is treated as antithetical to the conventional ethos of photography, which canonically stands as the evidence of an occurrence.