Abstract: A furnace is provided generally including an upper heating chamber and a lower work base or firing platform. The upper chamber provides the main source of heat to the materials to be heat-treated. The upper chamber contains a muffle within which is located a heater ring assembly. The heater ring assembly is located in the middle to upper half of the muffle and includes an annular heating element that is located between an outer insulation ring and an inner quartz sleeve. A cavity or channel extends through the muffle into which insulation materials and the heater ring assembly is located. The channel area in the muffle below the heater ring assembly allows for the placement of the firing platform therein. The firing platform includes insulation material and a heating element located in the upper portion thereof.

Abstract: A polycarbonate dimethacrylate which is the condensation product of 2 parts of hydroxyalkylmethacrylate of the formula. ##STR1## in which A is C.sub.1 -C.sub.6 alkylene, and 1 part of a bis(chloroformate) of the formula ##STR2## in which R is C.sub.2 -C.sub.5 alkylene having at least two carbon atoms in its principal chain and n is an integer from 1 to 4, is usable, admixed with a secondary monomer suitable for dental applications, such as BIS-GMA; UDMA or the like, as an adhesive system for dental restorative materials. Particularly useful is the novel condensation product of 2-hydroxyethylmethacrylate and triethylene glycol bis(chloroformate).Dental adhesives containing these components are suitable for application to enamel, pretreated dentin, porcelain and metallic surfaces. The dentin surfaces are pretreated by application of an alcoholic solution of an alkali metal salt of benzene sulfinic acid.

Abstract: A trimodal method of curing dental composite restorative materials involves the use of visible light illumination for the initial curing of the composite resin and a combination of dry heat and vacuum for the complete cure of the composite restorative materials. More specifically, the method for preparing dental restorative materials includes the steps of forming a dental restoration from a composite resin of a type conventionally employed in the dental profession, in which the composite resin includes a photosensitizing system for initiating polymerization of the composite resin upon exposure to visible light, an initiator for initiating polymerization upon application of heat and at least one filler; exposing the thus prepared restoration to a source of visible light to at least partially cure said composite resin and then subjecting the thus prepared restoration to a combination of heat and vacuum to complete polymerization of said complete resin.

Abstract: A polycarbonate dimethacrylate which is the condensation product of 2 parts of hydroxyalkylmethacrylate of the formula ##STR1## in which A is C.sub.1 -C.sub.6 alkylene, and 1 part of a bis(chloroformate) of the formula ##STR2## in which R is C.sub.2 -C.sub.5 alkylene having at least two carbon atoms in its principal chain and n is an integer from 1 to 4, is usable, admixed with a secondary monomer suitable for dental applications, such as BIS-GMA; PUDMA or the like, as an adhesive system for dental restorative materials. Particularly useful is the novel condensation product of 2-hydroxyethylmethacrylate and triethylene glycol bis(chloroformate).

Abstract: Phosphate-bonded investments and refractory die materials are provided upon which dental porcelains and/or alloy powders can be sintered. Inorganic fillers are mixed with appropriate binders to produce mold materials which exhibit very high thermal expansion properties without exhibiting any large or sudden change in their thermal expansion verse temperature profile. Investments and refractory die materials having thermal expansions of greater than 0.80% in the range of 25.degree.-500.degree. C. are provided by incorporating leucite (KAlSi.sub.2 O.sub.6) or calcium difluoride (CaF.sub.2), or both, as fillers for investments and refractory die materials.

Abstract: A glove box for establishing an inert gas working environment. The glove box has a housing defining a work chamber and a stovepipe section. Flexible glove sections are connected to the housing and can be inserted into the work chamber. A valve is connected to the stovepipe section for exiting gas from the work chamber and stovepipe section. The valve includes a rigid member with a seal connected thereto. The rigid member is biased by elastic members onto the stovepipe section with the seal therebetween.

Abstract: The system comprises a main casting unit and a glove box unit for reworking cast items. The main casting unit has a frame with a casting chamber, a heating element, a vacuum, a supply of inert gas and a rotatable casting arm for spin casting molten material into a mold. The arm is adapted to removably mount a crucible and mold at one end and, an adjustable counterweight at the other end. The heating element can be moved into and out of the path of the arm and is adapted to heat metallic material in the crucible. The main casting unit also has a driver that projects into the chamber for driving the casting arm with reduced wear on seals between the chamber wall and the driver. A safety bar is provided to prevent the arm from spinning except when desired. The main unit also has electrical and gas conduit connectors for connecting the glove box unit to the main unit.

Abstract: Improved titanium alloys for dental castings and processes for the preparation thereof, characterized by the incorporation of predetermined small amounts of one or more noble metals, preferably ruthenium, or rhenium, and optional predetermined small amounts of one or more rare earth metals, preferably cerium. The present alloys have improved corrosion and tarnish resistance under the conditions of use, and the preferred compositions including rare earth metals have improved oxidation resistance which improves their receptivity and bonding strength for enamels, porcelain surfacing materials or caps.

Abstract: A light curable pit and fissure sealant composition comprises 2,2-propane-bis [3-(4-phenoxy)-1,2-dihydroxy-propane-1- methacrylate] and triethylene glycol dimethacrylate in a 55:45 weight ratio, a polymerization initiator, titanium dioxide as an opaquing agent, and DEA-EMA of at least 95 percent purity as the polymerization accelerator. Optionally, up to 50% filler can be used.