Amalgam marginal quality assessment: a comparison of seven methods

Abstract

Black's class I classic cavities were cut in 120 sound extracted human premolars and restored with one of two silver amalgams, six different base combinations, with or without cavity varnish and then aged for 3 months or 1 year. Thereafter, the restored teeth were subjected to a bacterial or acid broth in vitro carious challenge for 36 days. Resin cast impressions were made of the restoration margin of each specimen before and after the carious challenge giving a total of 240 replicas. The replicas were examined in a scanning electron microscope (SEM) and the margins subjected to seven marginal assessment procedures: (i) ranking using micrographs of the margin; (ii) percentage length of marginal discrepancy; <iii) Mjor assessment using six groups; (iv) number of margin segments showing a discrepancy; (v) greatest gap size; (vi) ranking based firstly on gap size and then number of margin segments showing a discrepancy; and (vii) ranking based firstly on gap size and then percentage length of marginal discrepancy. The data from procedures (i), (ii), (vi) and (vii) were examined using one-way ANOVA; a linear logistic statistical analysis examined data from procedures (iii)-(v). Statistical significance was chosen at P < 0 05. It was found that procedure (vii) was able to discriminate between variables to a greater degree than all other procedures. It is recommended that a ranking system based on greatest gap size and percentage length of marginal discrepancy be used to assess marginal quality of amalgam restorations.

Research on Soil Fragmentation Characteristics Based on Fractal Dimension and Image Processing

“…Approximately 2/3 of the values were within the 95% confidence band. Only test #5 was outside the 95% prediction band, which again Engenharia Agrícola, Jaboticabal, v.43, n.1, e20220097, 2023 indicated that the sample data were statistically significant and relevant (Grossman & Matejka, 2010). Although the FD is the more common approach used internationally when assessing the state of scattered soil (Zhang et al, 2016), it is very complex, and recording the data requires measuring the triaxial dimensions of each fragmented body.…”

Avaliação da técnica de réplica para análise in vitro e in vivo das alterações da superfície da dentina hiperestésica e tratada com oxalato de potássio.

“…Dentre essas aplicações, podem ser destacados os estudos que utilizaram a técnica de réplica para observar a microestrutura dos tecidos duros dentários 40,112,28,17,105,80,57,70,110 , a abrasividade de dentifrícios 35 , a superfície de restaurações 50,122,49,29,77 , a interação de diferentes materiais com as estruturas dentárias 121,128 , a micromorfologia de tecidos moles e placa dental 68,124,125,106,9,107 , e o desenvolvimento de lesões cervicais não cariosas e as características de suas superfícies 25,8,4,14,127,11,9,10,78,13,62 .…”

“…Autores 50,5,28,25,54,122,124,2,8,4,125,14,106,127,11,9,10,107,78,27,33,13,49,80,62,128,29,36,77,57,70,110 recomendam as resinas epóxicas como material adequado para obtenção de …”

“…As técnicas de réplica relatadas na literatura utilizaram desde polietireno 40 , películas de celoidina embebidas em acetona 87,112 , até materiais de moldagem elastoméricos 50,49,105 , como as siliconas de condensação 35,5,28,67,25,54,122,2,4,14108,78 e as siliconas de adição 69,68,124,8,86125,106,127,11,9,10,107,27,33,121,17,80,128,29,36,77,57,70,110. . Um dos objetivos do presente trabalho foi avaliar a capacidade de reprodução da superfície dentinária, por meio da técnica de réplica, utilizando-se uma silicona de adição de consistência ultra-leve e uma resina epóxica.…”