Abstract: A low-fusing temperature porcelain compositions, methods of use thereof on metal or porcelain substrates to form dental prostheses and kits therefor. Compositions of the invention have a fusing temperature of less than 800.degree. C. and a coefficient of thermal expansion compatible with a substrate of metal or ceramic. Each composition includes, in weight percent of the composition, from 40 to 65 percent by weight SiO.sub.2, from 6 to 12 percent by weight Al.sub.2 O.sub.3, from 6 to 12 percent by weight Na.sub.2 O, from 5.5 to 10.50 percent by weight K.sub.2 O, from 1 to 3 percent by weight Li.sub.2 O, from 0.8 to 2.5 percent by weight CaO, from 0.8 to 4.0 percent by weight B.sub.2 O.sub.3 and from 0.1 to 0.8 percent by weight CeO.sub.2.

Abstract: An orthodontic bracket is made from crystalline alumina, preferably crystalline alpha-alumina. The bracket comprises a base member for attaching to a tooth and a body member extending from the base member. The body member includes walls that define an archwire groove. The walls comprise crystalline alumina. The bracket has sufficient strength to withstand normal torquing forces imparted by an archwire.

Abstract: An orthodontic bracket is made from crystalline alumina, preferably crystalline alpha-alumina. The bracket comprises a base member for attaching to a tooth and a body member extending from the base member. The body member includes walls that define an archwire groove. The walls comprise crystalline alumina. The bracket has sufficient strength to withstand normal torquing forces imparted by an archwire.

Abstract: The adhesive strength of alumina brackets to acrylic adhesive cements is enhanced by forming an essentially silica coating on the bonding surface of the bracket by the steps of coating said surface with an organosilicon compound such as a silane and then pyrolyzing the organosilicon coating to volatilize the organic components thereof to thereby leave an essentially silica coating.

Abstract: Orthodontic brackets are made from ion exchange strengthened glass. In a preferred embodiment, the glass is a lithium alumino silicate srengthened with sodium ions.

Abstract: The adhesion of crystalline alumina to adhesives is enhanced by coating the surface of the alumina that is to be in contact with the adhesive, with a very thin coating of a siliceous material such as sputter coated silica.

Abstract: There is disclosed an orthodontic bracket including a base member for attaching to a tooth and a body member extending from the base member. The body member includes walls that define an archwire groove. The walls are made of single crystal alumina. Preferably, the entire bracket is made of single crystal alumina, and most preferably, single crystal alpha-alumina or sapphire.

Abstract: Process for joining ceramic components in precise spatial relationship which comprises firing the ceramic components joined by a ceramic frit on a sagger tray having a coefficient of thermal expansion that matches that of the ceramic components.

Abstract: A process for producing a dental restoration wherein a bonding agent is disclosed for bonding dental porcelain to a nickel-containing metal core. The bonding agent is aluminum powder and an inert organic liquid carrier.

Abstract: A method of making low loss glass optical waveguides, wherein at least one coating of glass soot is deposited by the flame hydrolysis process on a starting member. The soot coating is heated to its consolidation temperature in an atmosphere containing helium and an amount of chlorine that is effective to substantially remove the water from the glass soot while the soot is being consolidated to form a dense glass layer. The starting member is removed unless it is to form a part of the optical waveguide. The resultant structure, including the dense glass body, is then drawn into a waveguide fiber.

Abstract: There is disclosed a method and apparatus for providing optically pure glass blanks, tubing, crucibles and the like for use in forming optical waveguides, lenses, prisms, filters, lamp envelopes and the like. A glass layer is formed at a high temperature on a mandrel which includes a support rod or tube upon which is disposed a layer of refractory metal wire, gauze, foil or the like. The mandrel is so constructed that stresses, which heretofore have developed in the glass layer during cooling, are avoided, and the mandrel is easily removed from the glass layer, thereby forming a hollow glass cylinder that is free from cracks, checks and the like.