Labial Reduction Guide for Laminate Veneer Preparation

This article describes a method of fabricating a labial reduction guide for laminate veneer preparations by using a digital tire tread depth gauge and orthodontic wire. The labial reduction guide can help clinicians to achieve accurate reduction of the labial surface. Minimally invasive porcelain laminate veneers have become a popular option in esthetic dentistry. Porcelain laminate veneers require only 25% to 50% of the amount of tooth reduction required for complete coverage restorations.Nevertheless, adequate labial reduction is important in creating optimal esthetics. However, excessive reduction can lead to compromised bond strength due to penetration of the enamel surface. Typically, the appropriate reduction is determined from a diagnostic waxing, and then a silicone index or thermoplastic matrix is made to guide preparation. Verifying the amount of reduction during tooth preparation from the guide can be problematic because the range of labial reduction for laminate veneers is small (0.3 to 0.9 mm). Freehand labial reduction can result in insufficient tooth removal.The purpose of this article was to describe the fabrication and use of a labial reduction guide (LRG) for laminate veneers

Custom Total Occlusal Convergence Angle Sticker Fabrication

This article describes a method of fabricating a custom total occlusal convergence angle sticker with photo editing software and label stickers. The custom total occlusal convergence angle sticker can help clinicians achieve an accurate degree of taper during axial wall reduction of tooth preparation

Impacts of Regulating Greenhouse Gas Emissions on Livestock Trade Flows

The policies that regulate greenhouse gas emissions would provide a significant burden to emission industries as well as final consumers, which can lead to a strong influence on international trade flows of commodities. This study examines the impact of regulating greenhouse gas emissions on livestock trade flows using a commodity specific gravity model approach. This study finds that regulating greenhouse gas emissions has a negative effect on livestock trade flows from countries restricting greenhouse gas emissions to unrestricting countries, from restricting to restricting countries, and from unrestricting to restricting countries.gravity model, livestock, regulating greenhouse gas emission, trade, Environmental Economics and Policy, Livestock Production/Industries,

Edge Chipping Resistance and Flexural Strength of Polymer Infiltrated Ceramic Network and Resin Nanoceramic Restorative Materials

Statement of problem Two novel restorative materials, a polymer infiltrated ceramic network (PICN) and a resin nanoceramic (RNC), for computer-assisted design and computer-assisted manufacturing (CAD-CAM) applications have recently become commercially available. Little independent evidence regarding their mechanical properties exists to facilitate material selection. Purpose The purpose of this in vitro study was to measure the edge chipping resistance and flexural strength of the PICN and RNC materials and compare them with 2 commonly used feldspathic ceramic (FC) and leucite reinforced glass-ceramic (LRGC) CAD-CAM materials that share the same clinical indications. Material and methods PICN, RNC, FC, and LRGC material specimens were obtained by sectioning commercially available CAD-CAM blocks. Edge chipping test specimens (n=20/material) were adhesively attached to a resin substrate before testing. Edge chips were produced using a 120-degree, sharp, conical diamond indenter mounted on a universal testing machine and positioned 0.1 to 0.7 mm horizontally from the specimen’s edge. The chipping force was plotted against distance to the edge, and the data were fitted to linear and quadratic equations. One-way ANOVA determined intergroup differences (α=.05) in edge chipping toughness. Beam specimens (n=22/material) were tested for determining flexural strength using a 3-point bend test. Weibull statistics determined intergroup differences (α=.05). Flexural modulus and work of fracture were also calculated, and 1-way ANOVA determined intergroup differences (α=.05) Results Significant (PLRGC=FC\u3ePICN; flexural strength: RNC=LRGC\u3ePICN\u3eFC; flexural modulus: RNCLRGC=PICN\u3eFC. Conclusions The RNC material demonstrated superior performance for the mechanical properties tested compared with the other 3 materials

Capital Mobility for Developing Countries May Not Be So High

International capital flows to developing countries have taken on considerable policy importance in recent years. There is disagreement, however, about whether financial capital mobility has become so high that developing countries have little ability to sterilize capital flows. This paper reviews several popular methods of estimating the degree of capital mobility for developing countries and shows that they are subject to potentially important upward biases due to inappropriate assumptions concerning the roles of domestic inflation and sterilization. Corrections for these factors can cut estimates of capital mobility by one half or more.sterilization; capital mobility; developing countries

Axial charges of octet and decuplet baryons

We present a study of axial charges of baryon ground and resonant states with relativistic constituent quark models. In particular, the axial charges of octet and decuplet $N$, $\Sigma$, $\Xi$, $\Delta$, $\Sigma^*$, and $\Xi^*$ baryons are considered. The theoretical predictions are compared to existing experimental data and results from other approaches, notably from lattice quantum chromodynamics and chiral perturbation theory. The relevance of axial charges with regard to $\pi$-dressing and spontaneous chiral-symmetry breaking is discussed

Effect of Toothbrushing On Shade and Surface Roughness of Extrinsically Stained Pressable Ceramics

Statement of problem The effect of toothbrushing on extrinsically stained pressable ceramic materials is unknown. Purpose The purpose of this in vitro study was to investigate the effects of toothbrushing on the shade and surface roughness of extrinsically stained, pressable ceramics. Material and Methods Two materials, leucite-based (IPS Empress Esthetic [EE]; Ivoclar Vivadent AG) and lithium disilicate-based ceramic (IPS e.max Press [EP]; Ivoclar Vivadent AG), were studied. For each material, 24 disk-shaped specimens, 10 mm (diameter)×3 mm (height) were fabricated. Three different methods (n=8) of applying extrinsic stains were performed on each material: glazed only (G, control group); stained then glazed (SG); and stained and glazed together (T). The specimens were brushed with a multistation brushing machine under a load of 1.96 N at a rate of 90 strokes per minute with a soft and straight toothbrush (Oral-B #35) and a 1:1 toothpaste and distilled water slurry. Shade and roughness were measured at baseline and at 72, 144, 216, and 288 hours, which is equivalent to 3, 6, 9, and 12 years of simulated toothbrushing for 2 minutes twice a day. A repeated measures ANOVA with staining technique as a fixed factor was used to evaluate shade and roughness (α=.05). Results For EE groups, no significant change was found after 12 years of simulated toothbrushing regarding shade and surface roughness, irrespective of staining techniques (P\u3e.05). However, EP groups demonstrated a significant shade change and an increase in surface roughness after 12 years of simulated toothbrushing. Shade change was found to depend on the method of applying stain. For the EP-SG technique, a significant shade change was observed only at the 9- to 12-year interval (P=.047). However, the EP-T technique demonstrated a significant difference in shade between baseline and 3 years (P=.005) and in the 6- to 9-year interval (P=.005). Surface roughness was only significantly affected at baseline and 3 years for the EP-T group (P=.005). Conclusions For the shade and surface roughness of the EE groups, no statistically significant difference was found after 12 years of toothbrushing, irrespective of the staining technique. The shade and surface roughness of the EP groups were significantly statistically affected by toothbrushing time; only shade changes were found to depend on technique