Abstract
The solubility of dental cements is important property due to their prolonged exposure to oral fluids. Тhe recommended standard is 0.2% mass loss for 24 hours. The aim of the study is to measure and compare the values of the solubility in different types of permanent cements as a function of time of exposure to the solvent. Four types of cements were selected: zinc phosphate (ZP), glass-ionomer (GI), resin-modified glass-ionomer (RG) and polycarboxylate (PC) cement. Totally 120 samples, equally divided in 4 series, were fabricated according to the experimental method recommended for in vitro laboratory measuring of the mass loss of the cement due to solubility. Distilled water was used as a solvent. The measuring of every sample weight was performed before and after immersing in solvent for 1, 7, 14 and 21 days and mass loss was calculated as a percent of initial weight of the sample. According to the results, the mass loss of selected cements after immersion in distilled water for the initial 24hours period was 0.28% for ZP cement, 0.32% for RG, 0.51% for PC and 0.57% for GI cement. After this period, the mass loss decreased and was minimal at the end of the third week. The precise evaluation of this basic characteristic is necessary for predicting clinical behavior of the permanent cement and the exact cement selection in every single case. Keywords: permanent cementation, dental cement, solubility, dissolution
Highlights
The process of fixed prosthetic restoration consists of consecutive clinical and laboratory procedures finishing with cementation which provides strong and long integration between 2 different structures – the abutments and the artificial prosthetic construction
Dissolution of permanent cement due to solubility will affect the longterm retention of fixed prosthetic construction or, at least, it will degrade the hermetic obturation in the region of crown margin which may lead to microleakage with consequent bacterial invasion of the gap (Jacobs and Windeler, 1991)
The obtained results confirmed the well-known data that investigated dental cements exhibit a relatively small loss of mass ( m1) when exposed to distilled water for the 24 hours period: 0.28% for zinc phosphate (ZP), 0.32% for resin-modified glass-ionomer (RG), 0.51% for PC and 0.57% for GI (Table 1). Small, according to these results, the amount of solubility and degradation of all cements is higher compared to ADA/ANSI standard which allows 0.2% for 24 hours
Summary
The process of fixed prosthetic restoration consists of consecutive clinical and laboratory procedures finishing with cementation which provides strong and long integration between 2 different structures – the abutments and the artificial prosthetic construction. Permanent fixed prosthetic luting cements are the evolution in dentistry is mostly connected to constant improvement of dental materials and instruments, the everyday practice shows that part of these. The same statement refers to permanent cements because the improvement of some physical characteristics not always results in better clinical performances (Diaz-Arnold et al, 1991; Donovan and Cho, 1999). One of them is solubility and disintegration of the cement caused by the oral fluids. All actual types of permanent cements exhibited solubility, erosion, disintegration and mass loss when exposed to fluids for prolonged time. Dissolution of permanent cement due to solubility will affect the longterm retention of fixed prosthetic construction or, at least, it will degrade the hermetic obturation in the region of crown margin which may lead to microleakage with consequent bacterial invasion of the gap (Jacobs and Windeler, 1991)
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