Biomedical subjects
L J Henderson
Publications and source records attributed to L J Henderson.
In vitro marginal leakage of cervical composite restorations lined with a light-cured glass ionomer.
The purpose of this research effort was to investigate the microleakage of cervical restorations lined with a light-cured glass-ionomer liner. Wedge-shaped cervical cavities were cut on extracted teeth with the gingival cavosurface margin involving dentin. The cavities were randomly assigned to each of each of three groups: (1) restored with a microfilled composite resin, (2) restored with a light-cured glass-ionomer liner and microfilled resin as in the "sandwich" technique, and (3) restored entirely with the light-cured glass-ionomer liner. Half of the specimens in each group were thermocycled. Microleakage of these restorations was assessed by dye penetration. The results showed that differences were more pronounced at the gingival margin. Composite restorations inserted over the glass-ionomer liner demonstrated significantly less leakage than when the liner was not used.
Effect of dentin age on effectiveness of dentin bonding agents.
The purpose of this research effort was to investigate the effect of age changes in dentin on the effectiveness of two dentin adhesives in minimizing microleakage at the tooth-restoration interface. Cavities were prepared in permanent teeth extracted from patients below 20 years or over 55 years of age. Wedge-shaped cervical preparations were made with the gingival cavosurface margin on dentin. Treatment groups were randomly restored with one of two composite restorative materials, together with the appropriate dentin adhesives. The control group specimens were restored with the respective composite restorative materials without the adhesives. All specimens were thermocycled, then placed in 0.5% basic fuchsin dye solution for 24 hours and subsequently sectioned longitudinally. Microleakage at the tooth-restoration interface was assessed by dye penetration. The results showed that the use of adhesives significantly reduced microleakage along the tooth-restoration interface. The adhesive formulated with glycidyl methacrylate was significantly more effective in reducing microleakage in dentin of the over-55 age group.
Effect of interchanging two composite resin system with a dentine adhesive.
There is a tendency to interchange dentine adhesives and composite resins when using composite resins for restorations. This study used marginal contraction gaps to test the effect of changing composite resins with a dentine adhesive. Cylindrical butt-joint cavities were prepared entirely in dentine using extracted human teeth. Two groups of control cavities (30 cavities per group) were restored with Prisma-Bond/Prisma-Fil and Heliobond/Heliomolar respectively. Two groups of test cavities (30 cavities per group) were restored using the dentine adhesive. Prisma Universal Bond with Prisma-Fil on one group and Prisma Universal Bond and Heliomolar in the other. Following thermocycling the marginal contraction gaps were measured and assessed. The results showed a significant reduction in marginal contraction gaps when using either composite resin with Prisma Universal Bond. This indicates a compatibility of both resins with the adhesive in this instance.
Contraction patterns in cavities tested with two dentin bonding agents.
Differences in microleakage at occlusal and cervical margins have been attributed to variations in the microstructure of enamel. The lack of homogeneity in dentin may have similar influences on the effectiveness of composite bonding. This study examined marginal contraction gaps occurring at the occlusal, cervical, mesial, and distal margins of dentin cavities restored with a composite restorative material, with and without the use of dentin bonding agents. Results showed that marginal contraction gaps at the dentin-restoration interface among the four sites in both treated and untreated cavities are not statistically different in size. Adhesion of composite restorative materials to dentin is not affected by the location of the margins.
Influence of preparation site on the effectiveness of two dentine adhesives.
There are morphologic and chemical variations in dentine in different parts of a single tooth. The aim of this study was to ascertain whether the site of restoration cavities was related to marginal contraction gaps at the restoration/dentine interface. The results showed no significant relationship when using a commercially available dentine adhesive. However, when an experimental dentine adhesive was used, there was a significant difference in the size of the marginal contraction gaps on the buccal and lingual surfaces of restorations.