Zvia Hirschfeld

Compatibility of a composite resin with pulp insulating materials. A scanning electron microscope study

Abstract A scanning electron microscope investigation of the interface between Adaptic and pulp insulating materials was conducted. The surface roughness, as caused by insulated materials, was observed to decrease in the sequence ZOE, Dycal, ZPC, and Copalite. Uncured Adaptic dissolved a cavity varnish. The clinical significance of these observations has been discussed.

Forced eruption technique: Rationale and clinical report

This article describes a refined, simplified forced eruption technique, and compared it with previous methods. This simplified method is easy to perform and encourages the use of adjunctive orthodontics in general practice. This relatively uncomplicated, quick, and cost-effective treatment can benefit patients.

Observations on cavity liners for composite resin restorations

Adhesion or surface roughness and discoloration at the interface between pulpinsulating materials and composite resins were taken as indications for interaction between the resins and the insulating materials. Some interaction occurred between all insulating materials and resins investigated. After separation of the restorative resins, the interaction of Dycal with the different composite resins varied considerably and decreased in the following sequence: Opotow, Natural, and Adaptic. The interactions of ZOE with Natural and with Adaptic were similar and more pronounced than the interaction at the Adaptic-Dycal interface but less pronounced than at the Dycal-Natural interface. A very thin film of Tubulitec was found to adhere to the composite resins in some areas. The adherence of liners containing calcium hydroxide to dentin was found to be generally stronger than the bond between these liners and composite resins. Separation of the composite resins caused tears in the varnishes and frequently in Hydroxyline. Almost completely intact layers of the varnish Copalite were observed on dentin, but Zahnlack apparently dissolved to a great extent in the resins. Among the liners containing calcium hydroxide, Dycal and Tubulitec were found to give rise to a high pH in samples of saliva, but Hydroxyline did not. Porosity and a folded surface were observed for Hydroxyline, indicating the entrapment of the solvent beneath a dry superficial layer.

Reaction of the rat molar pulp to direct capping with the separate components of Hydrex

Abstract Teeth treated with Hydrex, a hard-setting calcium hydroxide pulp-capping material, have shown pernicious features on the pulp. Hydrex is presented as two pastes which are mixed before use. Since one of them is based on calcium hydroxide, which promotes secondary dentin formation, it was thought that the resin-based paste is probably responsible for the deleterious effects. The present study performed on rat molars has shown that, whereas most of the pulps of teeth treated with the Hydrex base were healthy, all of those capped with the Hydrex catalyst presented pathologic changes, most of the pulps being necrotic.

Hydrex and its effect on the pulp. Preliminary findings on the rat molar.

Abstract The present study was performed on exposed pulps of rat molars capped with Hydrex. It is shown that Hydrex causes inflammation and necrosis of the pulp. Further clinicohistopathologic studies on the use of Hydrex should be encouraged, if it is assumed that human pulp may perhaps behave differently than rat molar pulp.

Marginal adaptation of glass-ionomer cements.

The effect of thermocycling on the marginal adaptation of two glass-ionomer cements was determined by means of scanning electron microscopy. Small gaps in the cement as well as at the enamel-cement interface were observed after curing, but these phenomena were not enhanced by thermocycling. Localized areas of surface deterioration were observed for both cements after thermocycling.

Dycal: Physical properties and resistance to amalgam condensation

Simulated clinical experiments showed that the hand condensation of amalgam on single or multiple layers of Dycal in Class II cavities does not cause significant fracture or displacement of the liner. Cyclic loading experiments demonstrated that the plastic deformation of Dycal decreases and its stiffness increases with each additional load cycle. This indicates that minor displacement of Dycal during amalgam condensation occurs mainly during the first thrusts with the condenser, and that its mechanical properties are improved by repeated condensation with heavy pressure. Cyclic loading tests may be of considerable value in the evaluation of the performance of liners during amalgam condensation.