Abstract
Objectives. 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.
Methods. 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.
Results. 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.
Significance. 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. (C) 2019 Published by Elsevier Inc. on behalf of The Academy of Dental Materials.
Original language | English |
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Pages (from-to) | 740-750 |
Number of pages | 11 |
Journal | DENTAL MATERIALS |
Volume | 35 |
Issue number | 5 |
Early online date | 2019 |
DOIs | |
Publication status | Published - May-2019 |
Keywords
- Mutans streptococci
- Composite resin
- Hardness
- Surface roughness
- Hydrophobicity
- Contact angle
- Microbial composition
- Biomaterials
- Degradation
- Esterases
- STREPTOCOCCUS-MUTANS BIOFILM
- GRADIENT GEL-ELECTROPHORESIS
- DENTAL RESIN COMPOSITES
- IN-VITRO
- SURFACE-ROUGHNESS
- ADHESION FORCES
- BIODEGRADATION
- RESTORATIONS
- DENTISTRY
- BACTERIA