ABSTRACT
Addition-reaction silicone impressions were made at 37 degrees C in two cylindrical trays of a truncated cone-shaped chromium-steel die. One tray size was used to obtain impressions with 1 mm thickness, from tray to the gingival margin of the preparation, while the second tray permitted a thickness of 4mm. The die was undercut aplical to the gingival margin using rings as described before permitting a variation of undercut depth from 0.5 to 1.5 mm. Stone dies were made from impressions after (1) cooling to 22 degrees C for 10 min or (2) cooling to 22 degrees C for 10 min and reheating to 37 degrees C for 30 min. Results revealed that reheating the impressions to mouth temperature before pouring the dies improved their accuracy and that depth of undercut had a definite but small effect on the accuracy of dies.
Subject(s)
Dental Impression Materials , Dental Impression Technique , Silicone Elastomers , Dental Impression Technique/instrumentation , Hot Temperature , Models, Dental , Reproducibility of Results , Stainless SteelABSTRACT
Polysulfide impressions were made at 37 degrees C in two cylindrical trays of a truncated cone-shaped chromium-steel die. One tray size was used to obtain impressions with 1 mm thickness from tray to the gingival margin of the preparation, while the second tray permitted a thickness of 4 mm. Stone dies were made from impressions after (1) cooling to 22 degrees C for 10 min or (2) cooling to 22 degrees C for 10 min and reheating to 37 degrees C for 30 min. Results revealed that reheating impressions to mouth temperature before pouring the dies improved their accuracy.
Subject(s)
Dental Impression Materials/chemistry , Dental Impression Technique , Sulfides/chemistry , Hot Temperature , Models, DentalABSTRACT
Dentin and enamel surfaces were treated with solutions of aluminum oxalate (AO), the pH of which was adjusted by glycine. Gluma as well as an enamel bonding agent were applied to the surfaces before the placement of a composite resin. On shear bond testing, there was obtained a strong adhesion that was influenced by the pH of the AO solutions. Dentin and enamel specimens for examination by scanning electron microscopy (SEM) were also prepared and treated as above. Enamel specimens showed a very definite etching pattern, and on the dentin surfaces a precipitate was observed. The amount of this product seemed to decrease as the pH increased.
Subject(s)
Aldehydes , Aluminum/pharmacology , Dental Bonding/methods , Dental Cavity Lining , Dental Cements , Glutaral , Glycine/pharmacology , Oxalates/pharmacology , Polymethacrylic Acids , Composite Resins , Dental Enamel/ultrastructure , Dental Stress Analysis , Dentin/ultrastructure , Dentin Permeability/drug effects , Humans , Hydrogen-Ion Concentration , In Vitro Techniques , Microscopy, Electron, Scanning , Oxalic AcidABSTRACT
In the present study, a number of modifications were introduced in the so-called Gluma resin--a new, simplified bonding system. The amount of acetone in its formulation was altered, or the acetone as well as part of the water were substituted by one of several volatile compounds with the purpose of obtaining a pretreatment of easier clinical application. Some modifications of the pH of the mixtures were also tried. Dentine specimens for shear bond testing were prepared and conditioned with an aluminium oxalate/glycine solution. The dentine surfaces were then treated with the modified Gluma resin mixtures before the placement of the composite resin. Gluma resin formulations containing tetrahydrofuran resulted in acceptable bond strengths, and with formulations of reduced pH, high bond strengths were obtained.
Subject(s)
Aldehydes , Composite Resins , Dental Bonding , Dentin , Glutaral , Polymethacrylic Acids , Acetates , Acetone , Aldehydes/chemical synthesis , Bisphenol A-Glycidyl Methacrylate , Composite Resins/chemical synthesis , Desiccation , Ethanol , Furans , Glutaral/chemical synthesis , Humans , Materials Testing , Methacrylates , Methanol , Polymethacrylic Acids/chemical synthesis , Solvents , Stress, Mechanical , WaterABSTRACT
Addition-reaction silicone impressions were made at 37 degrees C in two cylindrical trays of a truncated-cone-shaped chromium-steel die. One tray size was used to obtain impressions with 1 mm thickness from tray to the buccal and lingual surface of the steel die while the second tray permitted a thickness of 4 mm. Stone dies were made from impressions after (1) cooling to 22 degrees C for 10 minutes or (2) cooling to 22 degrees C for 10 minutes and reheating to 37 degrees C for 30 minutes. Results revealed that reheating the impressions to mouth temperature before pouring the dies improved their accuracy.
Subject(s)
Dental Impression Technique , Hot Temperature , Silicone Elastomers , Models, Dental , Surface PropertiesABSTRACT
A truncated cone-shaped chromium steel die was used to determine the influence of the bulk of elastomeric impression material and size of undercut on the dimension of stone dies. It was found that both conditions affect the accuracy of stone dies. The possible clinical implications of the inaccuracies were discussed.
Subject(s)
Dental Impression Materials , Calcium Sulfate , Dental Impression Technique , Elasticity , Models, Dental , Rubber , Silicone Elastomers , SulfidesABSTRACT
An instrument was introduced to determine the relationship between induced and permanent tensile deformation of selected elastomeric dental impression materials during and after setting. The method accurately recorded viscoelastic properties of impression materials.