Biofilm composition and composite degradation during intra-oral wear
[Display omitted] •Filler particle exposure at composite surfaces can be derived from contact angles.•Surface-exposure of filler particles reflects early degradation of composites.•Hardness is more influenced by a composite’s bulk matrix than by its surface.•S. mutans is a prominent member of the co...
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Veröffentlicht in: | Dental materials 2019-05, Vol.35 (5), p.740-750 |
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Sprache: | eng |
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•Filler particle exposure at composite surfaces can be derived from contact angles.•Surface-exposure of filler particles reflects early degradation of composites.•Hardness is more influenced by a composite’s bulk matrix than by its surface.•S. mutans is a prominent member of the composite-degradative oral microbiome.•S. mutans in oral biofilms degrades high rather than low ester-linkage composites.
The oral environment limits the longevity of composite-restorations due to degradation caused by chewing, salivary and biofilm-produced enzymes and acids. This study investigates degradation of two resin-composites in relation with biofilm composition in vitro and in vivo.
Surface-chemical-composition of two Bis-GMA/TEGDMA composites was compared using X-ray-Photoelectron-Spectroscopy from which the number ester-linkages was derived. Composite-degradation was assessed through water contact angles, yielding surface-exposure of filler-particles. Degradation in vitro was achieved by composite immersion in a lipase solution. In order to evaluate in vivo degradation, composite samples were worn in palatal devices by 15 volunteers for 30-days periods in absence and presence of manually-brushing with water. PCR-DGGE analysis was applied to determine biofilm composition on the samples, while in addition to water contact angles, degradation of worn composites was assessed through surface-roughness and micro-hardness measurements.
In vitro degradation by lipase exposure was highest for the high ester-linkage composite and virtually absent for the low ester-linkage composite. Filler-particle surface-exposure, surface-roughness and micro-hardness of both resin-composites increased during intra-oral wear, but filler-particle surface-exposure was affected most. However, based on increased filler-particle surface-exposure, the high ester-linkage composite degraded most in volunteers harvesting composite biofilms comprising Streptococcus mutans, a known esterase and lactic acid producer. This occurred especially in absence of brushing.
Degradation during intra-oral wear of a low ester-linkage composite was smaller than of a high ester-linkage composite, amongst possible other differences between both composites. S. mutans herewith is not only a cariogenic, but also a composite-degradative member of the oral microbiome. |
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ISSN: | 0109-5641 1879-0097 |
DOI: | 10.1016/j.dental.2019.02.024 |