Rafaella Tonani

Influence of Different Types of Resin Luting Agents on Color Stability of Ceramic Laminate Veneers Subjected to Accelerated Artificial Aging

The aim of this study was to evaluate the influence of accelerated aging (AAA) on the color stability of resin cements for bonding ceramic laminate veneers of different thicknesses. The occlusal surfaces of 80 healthy human molars were flattened. Ceramic laminate veneers (IPS e-max Ceram) of two thicknesses (0.5 and 1.0 mm) were bonded with three types of luting agents: light-cured, conventional dual and self-adhesive dual cement. Teeth without restorations and cement samples (0.5 mm) were used as control. After initial color evaluations, the samples were subjected to AAA for 580 h. After this, new color readouts were made, and the color stability (ΔE) and luminosity (ΔL) data were analyzed. The greatest color changes (p<0.05) occurred when 0.5 mm veneers were fixed with light-cured cement and the lowest when 1.0 mm veneers were fixed with conventional dual cement. There was no influence of the restoration thickness when the self-adhesive dual cement was used. When veneers were compared with the control groups, it was verified that the cement samples presented the greatest alterations (p<0.05) in comparison with both substrates and restored teeth. Therefore, it was concluded that the thickness of the restoration influences color and luminosity changes for conventional dual and light-cured cements. The changes in self-adhesive cement do not depend on restoration thickness.

Effect of Polishing and Brushing on Removal of Cigarette Smoke Stains from Artificial Teeth

Color alteration is still a disadvantage of acrylic resin teeth and this problem seems to be greater in smokers. The objective of this study was to evaluate the efficiency of polishing and brushing on removal of stains from artificial teeth submitted to cigarette smoke. Forty denture teeth of distinct shades (62 and 69) were selected. The teeth were divided into 4 groups (n= 10), according to the tooth shade and method of stain removal performed: Groups 1 and 2 were submitted to the smoke of 20 cigarettes, and after new color readouts, were submitted to polishing with pumice stone and Spanish white paste. Groups 3 and 4 were submitted to 4 cycles of 5 cigarettes interspersed with standardized manual brushing. The values of color stability (DE) were compared using 2-way ANOVA, Bonferroni test (p 3.3). After exposure to 20 cigarettes, the greatest degree of color change occurred for teeth in shade 62. Polishing significantly reduced the color change for groups 1 and 2, however, without significant difference between them. For Groups 3 and 4 there was no difference between the teeth of shade 62 and 69. When the treatments for each tooth shade were compared alone, there was similarity between polishing and brushing irrespective of the shade of samples. Routine manual brushing and common clinical polishing methods were capable of removing a large portion of staining caused by cigarettes, and there was no difference between the methods. ˚

Relação entre a divulgação de pagamentos baseados em ações e os níveis de Governança Corporativa da BM&FBovespa

The Agency Theory foresees a misalignment between the interests of shareholders and managers, because of various utilities. A mechanism that can be used to align the interests corresponds to the share-based payment plan, which proposes to create incentives for the management seeking to maximize the value of the companys value. In addition, companies can adopt differentiated corporate governance practices, which imply greater transparency and legal protection to non-controlling shareholders. The implementation of regulatory Technical Pronouncement of this type of incentive plan is recent, being necessary to study your application. According to research on accounting disclosure (VERRECCHIA, 2001), managers have incentives to make decisions about the level of disclosure of accounting information. This study investigated the relationship between the disclosure of share-based payment and the corporate governance levels of the BM&FBOVESPA. The compliance analysis of the 2011 financial statements of companies with based payment followed the disclosure rules of the CPC 10 (R1). The sample consisted of 156 companies listed on the BM&FBOVESPA that has share-based payment, of which 122 belonged to levels of corporate governance and 34 the traditional segment, evaluated by non-parametric test Wilcoxon-Mann-Whitney. It was concluded that companies belonging to segments of corporate governance has higher disclosure score about share-based payment compared with companies belonging to the traditional listing segment of the BM&FBOVESPA. This is due to the incentives given to managers, such as listing the company on the BM&FBOVESPA and instruments of variable remuneration to align interests such as share-based payment.