James L. Fuller

The ability of foods to stain two composite resins

In this bench study, coffee and soy sauce stained composite resin restorations to a significantly greater degree than did tea or cola beverage. Generally, the greatest degree of staining with all samples occurred during the first week of the study time. The stain penetration was superficial and was estimated to be 5 mu or less.

Cuspal deformation and fracture resistance of teeth with dentin adhesives and composites.

This study investigated the effect of polymerization shrinkage of posterior composite (Herculite) on the dimensions and fracture strength of human maxillary premolars with a phosphonate-ester DBA (Bondlite) and a second DBA comprised of 4-META with MMA/TBB (Superbond). The individual role of etched enamel and nonetched dentin bonding was also studied with high-copper amalgam used as a control. Two sizes of preparation isthmus were designated for evaluation of the effect of the polymerization contraction on weakened teeth. The following conclusions were drawn. 1. Narrow intracoronal tooth preparations were significantly stronger than wider, expansive preparations. There was no difference among the narrow isthmus preparations restored with amalgam or acid etching and composite. 2. There was a significant expansion in tooth dimension when MOD cavities were restored with amalgam. 3. Teeth with narrow isthmus preparations using composite bonded with Bondlite adhesive to etched enamel demonstrated a significant contraction compared with Superbond DBA. 4. Composite restorations using Superbond DBA in wide MOD cavities significantly improved the fracture strength of maxillary premolars. 5. Superbond DBA with composite restorations benefited the tooth in dimensional change and fracture strength. 6. There was a positive correlation between the fracture strength and tooth dimension.

The fracture strength of amalgam overlying base materials

Conclusions reached within the constraints of this study showed the following: 1. Fracture strength of Class II amalgam restorations decreased as the thickness of the bases increased. 2. Fracture strengths of amalgam restorations based with different thicknesses of zinc phosphate cement underline with 0.5 mm Dycal were not different from each other. 3. The strength of the restorations varied with the type of base. Zinc phosphate cement is equal to no base and superior to zinc phosphate cement plus Dycal, which is equal to Dycal. Dycal is superior to Cavitec, which is the same as Cavitec plus Dycal. 4. The base materials did not fracture. The amalgam restorations were stronger over a base with a higher modulus of elasticity, indicating that modulus of elasticity of a base is more important than compressive strength in supporting an amalgam restoration. 5. There is no advantage (no improvement in resistance to fracture of the amalgam restoration) to be gained from placing zinc phosphate cement over Dycal. 6. When a calcium hydroxide liner is not needed, the cements with a higher modulus of elasticity, such as zinc phosphate cement and reinforced ZOE, will provide for stronger amalgam restorations than Cavitec and unreinforced ZOE.

Retentiveness of enamel-resin bonds using unfilled and filled resins

Abstract The shear strength of composite resin from etched enamel surfaces was tested using five different techniques for placing composite resin and/or unfilled resin. The results did not show significant shear strength differences among the various methods of placing unfilled resins before filled resin or placing filled resin alone.

Composite and intermediate resin tag formation in acid-etched enamel: A scanning electron microscopy evaluation

A divergence of opinion exists regarding the efficacy of the use of an intermediate or unfilled resin in the acid-etch technique of restorative dentistry. For example, the manufacturers of Concise (3M Co., Dental Products Div., St. Paul, Minn.), Adaptic (Johnson and Johnson Dental Products Co., East Windsor, N.J.), and Silar (3M Co., Dental Products Div.) endorse the use of an intermediate resin, while Isopast (Vivadent [USA] Inc., Buffalo, N.Y.) is recommended by the manufacturer for use directly on the etched enamel surface. The main concerns are retention and sealing, which are directly related to the capacity of the resin to wet and thus adapt to the acid-etched enamel. In turn, a good indication of proper wettability is provided by the formation of resin tags in the etched enamel. The purpose of this study was to examine tag formation of selected composite and intermediate resins through the medium of scanning electron microscopy (SEM).