Técnica simplificada de fabricação de registro de inserção em prótese parcial removível / Simplified technique to manufacture a registration device of the path of insertion for removable partial dentures

Neste trabalho é demonstrada uma técnica simplificada de execução e baixo custo de confecção de um registro de inserção/remoção em prótese parcial removível utilizando materiais simples, como um prego ou broca descartada, e Godiva de alta e baixa fusão. Desta forma, este método possui a vantagem de construir um dispositivo que poderá ser aplicado em inúmeros modelos de gesso de um mesmo paciente.

The present study presents a simple and low-cost technique for the manufacture for a device to record the path of insertion for removable partial denture using simple materials, such as a discarded drill or pin, and mpression compound. Thus, this method has the advantage to build a device that can be applied in several cast models of the same patient.

Masking ability of opaque thickness on layered metal-ceramics

This study evaluated the masking ability of two opaques applied in different thicknesses. Eighty NiCr metal discs 16 mm in diameter and 1.0 mm thick were prepared. The disks were divided into 8 groups (n = 10). Ceramic opaque in paste (groups 1 to 4) or powder (groups 5 to 8) presentations were applied. They were machined with aluminum oxide burs to the following thicknesses: G1 and G5 = 0.10 mm; G2 and G6 = 0.15 mm; G3 and G7 = 0.20 mm and G4 and G8 = 0.30 mm. Dentin ceramic 0.7 mm thick was applied over these discs, sintered and glazed according manufacturer’s instructions. Color was assessed with a Minolta CR10 spectrocolorimeter on the CIELab scale. Powder opaque had higher values on (L) and (ΔE) variables, and lower values on (a) and (b) variables compared to paste opaque. For opaque thickness, 0.10 mm had higher ΔE than all other thicknesses. L values were higher for 0.20 mm and 0.30 mm. Lowest and highest a* values were observed for 0.10 mm and 0.30 mm, respectively. No difference was observed for b* values. There were differences between paste and powder opaque types; 0.10 mm thickness behaves differently from the other thicknesses, with higher ΔE, while 0.15 mm does not differ statistically from thicker layers.

O objetivo deste estudo foi avaliar a capacidade de mascara mento de duas cerâmicas opacas para metalocerâmicas aplicadas em espessuras diferentes. Foram confeccionados 80 discos metálicos de NiCr (High Bond) com 16 mm de diâmetro e 1,0 mm de espessura. Os discos foram divididos em 8 grupos (n=10) e aplicadas as cerâmicas opacas (Noritake) em pasta (grupos de 1 a 4) e em pó (grupos de 5 a 8). Estas foram usinadas com pontas de óxido de alumínio até atingir as seguintes espessuras: G1 e G5 = 0,10 mm; G2 e G6 = 0,15 mm; G3 e G7 = 0,20 mm e G4 e G8 = 0,30mm de espessura. A cerâmica de dentina opaca foi aplicada (0,7 mm) e realizado o glazeamento. A cor foi avaliada com Espectrocolorímetro (Minolta CR10) e foi aplicada análise de variância com para p<5%. Resultados: O opaco em pó apresentou valores maiores estaticamente significantes nas variáveis (L*) e (ΔE), ocorrendo o inverso nas outras duas variáveis. Quanto à espessura de opaco, os valores podem ser agrupados da seguinte forma, segundo os testes complementares aplicados: variável (L*): (0,10 = 0,15) < (0,20 = 0,30); variável (a*): (0,10) < (0,15 = 0,20) < (0,30); variável (b*): não houveram diferenças estatisticamente significantes; variável (ΔE): (0,10)< (0,15 = 0,20 = 0,30). Conclui-se que houve diferença entre os tipos de opaco em pasta e em pó e que todas as espessuras testadas, exceto a de 0,10 mm, podem ser usadas sem alteração significativa da cor.

Influence of refractory on the color of VM7 metal free ceramics.

INTRODUCTION: The aim of this study was to evaluate the influence of metal oxides from investment dies on the color of metal-free VM7 ceramic. MATERIALS AND METHODS: Forty circular patterns were made with an elastic gelatin duplicator. These were divided into four groups (n = 10) for pouring the investment: G1, Begoform (Bego); G2, Ducera Lay Superfit (DeguDent GmbH); G3, Duravest (Polidental), and G4, Refrax Magnum (CNG). Refractory dies were subjected to the degassing process for gas and metal oxide elimination, and the testing was done with the application of two layers of VM7 ceramic. These layers were sinterized in accordance with the manufacturer's recommendation and then glazed. For the control group, 10 additional VM7 ceramic discs were made without the use of any investment die. The ceramic's control color and the tested groups were analyzed with the aid of a portable colorimeter (Minolta CR-10) in the CIELab. The color change (ΔE) of the specimens from the tested groups was obtained, and the data were submitted to one-way ANOVA and post-hoc Tukey's test. RESULTS: All tested groups had a color change from the control group. G1 (5,3) and G2 (5,3) were those that showed the greater color change and did not show statistical differences between themselves; G3 (3,3) and G4 (3,1) were those that showed the least color change from control group and did not show statistical differences between themselves. CONCLUSION: Once all investments present a perceptible color change from the control group, color selection should be done with a laboratory-produced color scale.

Color variation of acrylic resins immersed in pigment beverages according to the consume habits: a pilot study

AIM: evaluate the color changes in acrylic resins immersed in two pigmented beverages in different time periods, proportional to the frequency and volume of consume by the population with and without the use of artificial saliva. MATERIAL AND METHODS: Thirty thermo-polymerizable resin disks were confectioned with 3.0 +- 0.1 mm thickness, initially immersed in distilled water for 24 hours and randomly divided into 2 groups (n=15): GC ­ with artificial saliva and GS ­ without artificial saliva. They were, then, subdivided into 3 subgroups (n=5): G1 ­ distilled water (control); G2 ­ red wine; G3 ­ black tea. These groups were daily immersed inside beverages for 15 days, with daily immersion frequency equal to the beverage ingestion and the period of each immersion equal to 1 minute/10 ml of beverage per capita. Between each immersion the disks were stored inside distilled water. The color of resins was measured according to the CIE-Lab scale before and after the immersion periods, and the color variation was calculated (ΔE). The values ΔL*, Δa* e Δb* were also evaluated. RESULTS: Analysis of variance was performed, and have shown significant difference (p<0.05) among G1 and the other solutions, without significant difference between G2 and G3 for ΔE, ΔL, Δa and the module Δb. There was no difference between GC and GS. CONCLUSION: It was concluded that the use of artificial saliva did not change pigmentation degree and that wine presents similar changes to the tea, considering the parameters used.

Efeito da diluiçäo do Rematitan Plus líquido sobre as dimensöes de uma incrustaçäo MOD / Effects of the dilution of the Rematitan Plus liquid on the dimensions of an inlay MOD

Avaliou-se o efeito da diluiçäo do Rematitan Plus líquido sobre as dimensöes de uma incrustaçäo MOD. A partir de uma matriz, foram confeccionados doze padröes de cera divididos em três grupos. Cada grupo foi incluído em uma diluiçäo de Rematitan Plus líquido dentre aquelas recomendadas pelo fabricante (mínima, máxima e uma intermediária). A partir de marcas de referência feitas na matriz, as peças foram medidas no sentido M-D e V-L. Observou-se que a variaçäo na diluiçäo näo alterava signicativamente as dimensöes da incrustaçäo na maioria dos casos. Além disso, observou-se que as propriedades da cera utilizada como padräo para a confecçäo das incrustaçöes foi mais significativa na alteraçäo dimensional que a diluiçäo do líquido do revestimento