ABSTRACT
OBJECTIVES: The aim of this study was to assess the effect of different extraction media and time on the amount and pattern of fluoride release from compomers. MATERIAL AND METHOD: 42 specimens (n = 7 per group) in disc forms (7 mm diameter, 2 mm thickness) from three different compomers (were placed in artificial saliva (pH = 7.0) and lactic acid (pH = 5.2). The amount of the fluoride in these solutions were measured at 1st, 7th, 14th, 21th and 28th day time intervals by means of the fluoride ion selective electrode. The fluoride amount was calculated by concentration (ppm). The amount and the pattern of fluoride release was dependent on both the material, the storage medium and time. RESULTS: Fluoride release was evident for all the compomers but the rate of release varied considerably between the materials. Significant differences were also found between the different types of compomer (p < 0.01). A time dependent increase in the fluoride content was observed for all the compomers in both media. For all the tested materials, the fluoride release was higher in the lactic acid (p < 0.01). The amount of fluoride release was the most from Compoglass followed by Dyract AP and Glasiosite at 28th days, in both artificial saliva and lactic acid respectively. The least amount of fluoride release was observed at the first day.
OBJETIVOS: O objetivo deste estudo foi determinar o efeito de diferentes meios e tempo na quantidade e padrão de liberação de flúor por compômeros. MATERIAL E MÉTODO: 42 espécimes (n = 7 por grupo) em discos (7 mm de diâmetro, 2 mm de espessura), três compômeros diferentes, foram colocados em saliva artificial (pH 7,0) e ácido lático (pH 5,2). A quantidade de flúor nas soluções foram medidas a intervalos semanais, do 1º ao 28º dias (quatro semanas) por meio de eletrodos seletivos para íons flúor. A quantidade de flúor foi calculdada por concentração(ppm). A quantidade e o padrão da liberação de flúor variou consideravelmente tanto do material, do meio de armazenamento e tempo. RESULTADOS: A liberação de flúor foi evidente por todos os compômeros, mas a taxa de liberação variou consideravelmente entre os diferentes tipos de compômeros (p < 0.01). Um aumento relacionado com o tempo no conteúdo de flúor foi observado para todos os compômeros em ambos os meios. Para todos os materiais testados, a liberação de flúor foi maior no ácido lático (p < 0.01). A quantidade de liberação de flúor foi maior pelo Compoglass®, seguido pelo Duract AP® e Glasiosite® aos 28 dias, tanto na saliva artificial como no ácido lático respectivamente. A menor liberação de flúor foi observada no primeiro dia.
Subject(s)
Compomers/chemistry , Fluorides/chemistry , Lactic Acid , Saliva, Artificial/chemistry , Dental Amalgam/chemistry , Glass Ionomer Cements/chemistry , Composite Resins/chemistry , Time FactorsABSTRACT
OBJECTIVE: To evaluate retentive strength and film thickness of complete metal crowns cemented to overtapered teeth with 3 different cements after the application of airborne-particle abrasion. METHOD AND MATERIALS: Sixty extracted maxillary molar teeth were embedded in autopolymerizing resin. Crowns were prepared with 30-degree overtapered axial walls and a 1-mm shoulder margin using a water-cooled cylindrical airborne-particle abrasion device. Then, 60 complete crowns were made from a nickel-chromium alloy. Teeth and crowns were assigned to 2 groups, 30 to the control group and 30 to the experimental group to undergo airborne-particle abrasion. In the first part of study, 30 teeth from the experimental group were submitted to the silicon-replica technique and their buccolingual cross sections were measured so that cement film thickness could be measured before airborne-particle abrasion. Three measurements using a light microscope were made in 7 regions of each tooth. In the second part of study, complete metal crowns with and without airborne-particle abrasion were distributed into 3 groups with 10 teeth each to be cemented with zinc phosphate, polycarboxylate, or resin-modified glass ionomer. All specimens were subjected to a tensile bond test in an universal testing machine at a crosshead speed of 0.1 mm/min until failure. The results were then evaluated with Student t test at a 5% level of significance. RESULTS: The film thickness showed no statistically significant differences among groups (P > .05). There was a significant difference between the control and experimental groups, with an increase in all 3 cements after airborne-particle abrasion (P < .05). The highest retentive strength in the control group was found with resin-modified glass ionomer (141.4 +/- 56.7 N), but there was no significant difference between the resin-modified glass ionomer (141.4 +/- 56.7 N) and zinc phosphate (121.4 +/- 24.2 N) (P > .05). Retentive strength of polycarboxylate was the lowest (78.03 +/- 16 N) (P < .05). For the experimental group, the difference among the zinc phosphate (220.5 +/- 83.8 N), polycarboxylate (185.4 +/- 60.8 N), and resin-modified glass ionomer (228.9 +/- 62.4 N) was not statistically significant (P > .05). CONCLUSION: Airborne-particle abrasion had a positive effect on the retention of complete metal crowns when the crowns were cemented with zinc phosphate cement, polycarboxylate cement, or resin-modified glass-ionomer cement.
