Change in Surface Hardness of BisGMA/TEGDMA Polymer due to Enzymatic Action

Abstract

The surface microhardness of specimens made of a BisGMA/TEGDMA polymer was measured before and during treatment for 60 days with phosphate buffer or phosphate-buffered esterase solution with an activity corresponding to the mean hydrolase activity of human saliva. The hardness of the buffer-treated specimens was unchanged during the incubation period, while that of the esterase-treated specimens decreased gradually. After about five days of treatment, no further change in hardness was observed for up to 60 days. Based on the difference in the calculated hardness of the specimens as a function of the applied load during measurement, it was estimated that the mean microhardness of the outermost surface layer of the esterase-treated specimens was diminished by about 15%, compared with that of the buffer-treated specimens. From these results, it was concluded that the wear resistance of a BisGMA/TEGDMA polymer is most likely diminished by hydrolases in saliva.

Biodegradation of Commercial Dental Composites by Cholesterol Esterase

“…x -a 16 ± 14 + 12 + 10 + In the early 1990s, Munksgaard and colleagues presented several research studies (Freund and 6--Munksgaard, 1990;Munksgaard and Freund, 1990;Larsen and 4-Munksgaard, 1991;Larsen et al, 1992) which implicated hydrolytic 2 salivary enzymes in the reduction of material hardness, in the generation of methacrylic acid as a°-degradation by-product, and in 22 m promoting an increase in the wear of methacrylate-based polymers Figure 4. Relative peak arei which are used in dental materi-incubation with buffer and c als.…”

“…The hydrolytic activity of saliva (Chauncey, 1961;Nakamura and Slots, 1985;Zambon et al, 1985) has been clearly linked to material degradation Munksgaard and Freund, 1990;Larsen and Munksgaard, 1991;Larsen et al, 1992). More recently, it was shown that one enzyme contributing to the hydrolytic activity, pseudocholine esterase, was able to generate biodegradation products from commercial dental'composites (Leung et al, 1997).…”

Surface and bulk properties of dental resin- composites after solvent storage

“…There is a large range of available resin-composites, generalisation about their behaviour and performance should be made d e n t a l m a t e r i a l s x x x ( 2 0 1 6 ) xxx-xxx or collectively, determine the longevity of the restoration [1][2][3][4][5][6]. From a material aspect, the performance of the resincomposite restoration depends on several factors including the monomer system, the filler type, filler loading and the extent of cure [7].…”

Surface Changes of Fluoride-Releasing Composites: a Comparison of in Vivo and in Vitro Results

“…In vitro studies by Leung et al (1983), Greener et al (1984), Watts et al (1986), and Chadwick et al (1990) showed convincingly that the surfaces of composites stored in water are softened over time as a result of water uptake. In vitro, it has also been demonstrated that composites are softened by exposure to ethanol or organic acids (Asmussen, 1984;Wu et al, 1984;McKinney and Wu, 1985) as well as by the enzymatic activity of human saliva Munksgaard and Freund, 1990;Larsen and Munksgaard, 1991;Larsen et al, 1992). In the in vivo study by van Groeningen et al (1986), however, the surface microhardness of composites increased slightly; softening did not occur after 30 days.…”