Effects of radio-opacifier addition in dental impression material.

OBJECTIVE: The aim of this in vitro study was to determine the effects of barium sulfate addition in two dental impression materials previously proved as radiolucent. MATERIALS AND METHODS: An irreversible hydrocolloid (IH) and polyether (PE) were tested for optical density, linear dimension stability and detail reproduction. STATISTICAL ANALYSIS USED: The optical density data were submitted to Kolmogorov-Smirnov normality test and compared with two-way ANOVA and Tukey (alpha=0.05). RESULTS: The results of optical density (pixel) were: IH control 45.24 f (+/-7.6), PE control 54.93 e (+/-4.45), PE 5Wt% 60.43 d (+/-6.27), IH 1Wt% 61.54 cd (+/-5.3), PE 1Wt% 66.9 bc (+/-5.05), IH 5Wt% 67.17 b (+/-6.01), PE 10Wt% 84.55 a (+/-5.14), IH 10Wt% 85.33 a (+/-5.53). On detail reproduction, polyether control was able to copy the 6 microm line. Adding 1 or 5Wt% of barium sulfate have not change this characteristic. For the irreversible hydrocolloid, the control group was able to copy a line with 14 microm, however, adding 1Wt% barium sulfate, the capability decreased to 22 microm. Adding barium sulfate in the polyether promoted an increase in between the copied lines, for the control, the average distance was 931.6 microm, 936 microm to 1Wt% and 954.5 microm to 5 Wt%. For the IH, the control presented 975 microm in comparison to 987.25 microm for 1 Wt% samples. CONCLUSION: The addition of barium sulfate was capable of increasing significantly the optical density of tested material, have changed the linear dimension stability, however, have not interfered in detail reproduction only for PE.

Radiopacity of impression materials using an indirect digital system / Radiopacidade de materiais de moldagem usando um sistema digital indireto

Purpose: This in vitro study evaluated the radiopacity of impression materials using an indirect digital system. Methods: Samples of four polyvinyl siloxanes, one polyether, one polysulfide, and one irreversible hydrocolloid were fabricated with 1.0, 1.5, and 3.5mm-thickness. Three samples of different thickness were placed on the Digora optical plate and exposed. The optical density (pixels) was recorded in three areas resulting in a total of 360 measurements. Data were analyzed by 2-way ANOVA and Tukey tests (α=0.05). Results: Significant differences were observed among all materials and thicknesses tested (P<0.001). Irreversible hydrocolloid and polyether showed the lowest optical density. Polysulfide showed the highest optical density under all evaluated conditions. Conclusion: There was a significant difference in optical density for all impression materials tested. Composition changes are suggested to allow radiographic detection and improve safety during clinical use of impression materials.

Objetivo: Este estudo in vitro comparou a radiopacidade de materiais de moldagem usando um método radiográfico digital indireto. Metodologia: Amostras de quatro polivinil-siloxanos, um poliéter, um polissulfeto e um hidrocolóide irreversível foram confeccionadas com alturas de 1, 1,5 e 3,5mm. Três amostras das diferentes espessuras foram dispostas sobre uma placa óptica Digora e exposta. A densidade óptica (pixels) foi registrada em três diferentes áreas de cada amostra. Os dados foram analisados pelo teste de análise de variância de dois fatores e teste de Tukey (α=0,05). Resultados: Diferenças significantes foram observadas entre todos os materiais e espessuras testadas (P<0,001). O hidrocolóide irreversível e o poliéter apresentaram a menor densidade óptica. O polissulfeto apresentou a maior densidade óptica em todas as condições avaliadas. Conclusão: Há diferença significativa na densidade óptica dos materiais de moldagem avaliados. Alterações na composição são necessárias para facilitar a detecção destes materiais a fim de aumentar a segurança no uso clínico.