Abstract: For anchoring a prosthesis within a bone by means of a bone cement (32), prothesis shaft has a surface which is formed by the surfaces of a plurality of spheres (23 . . . 25) partially penetrating each other and having radii which decrease from the proximal towards the distal shaft end. The transitional zones between adjacent spheres (23 . . . 25) are concavely rounded. This shape is especially suited for use with a glass ionomer-type bone cement, because the shaft exerts substantially only compressive forces on the cement, whereas tensile and notch stresses, with respect to which this kind of cement exhibits little resistance, are largely avoided.

Abstract: A pneumatically operated submersible pump and method for operating the same including a housing having a chamber disposed therein. A first opening is positioned in the housing for permitting liquid to flow into the chamber. A seal is operatively disposed within the camber for selectively sealing the first opening. A source of compressed air is provided for supplying compressed air to the chamber. A discharge opening is positioned in the housing for withdrawing liquid from the chamber. A predetermined quantity of liquid initially flows into the chamber through the first opening for imparting movement to the seal means for subsequently sealing the first opening. Thereafter compressed air is supplied to the chamber which displaces the liquid through the discharge opening thereby releasing the seal for repeating a pumping operation by again permitting the predetermined quantity of liquid to flow into the chamber through the first opening.

Abstract: (Methy)acrylic acid esters of the general formula(Mo).sub.n --[--A--O--CO--CH.sub.2 --O--CH.sub.2 --CH.sub.2 --O--CH.sub.2 --CO--O--].sub.x --A--(OM).sub.nare described whereinA is an alcohol radical having at least 4 chain atoms between two junction sites.M is CH.sub.2 .dbd.C(R.sup.1)--CO wherein R.sup.1 stands for hydrogen or methyl,n is 1 or 2, andx is 0.3 to 3.These esters are suited for the preparation of dental compositions.

Abstract: Isobutylene polymers are prepared continuously, in aliphatic C.sub.3 -C.sub.6 -hydrocarbons in the presence of soluble cationic polymerization initiators and coinitiators at from -40.degree. to 40.degree. C. and under from 0.01 to 10 bar, and the solvents and monomers vaporized during the polymerization are recycled, by a process in which the liquid stream of the monomer solution, containing 40-95, in particular 50-85, percent by weight of the monomers, the liquid streams of the recycle and of the coinitiator solution and the separate stream of the initiator solution are combined in a first zone containing the polymerization zone, and the resulting polymer solution is taken off continuously through a second zone vertically below the first zone. The liquid streams of the monomer solution, the coinitiator solution and the recycle can furthermore be fed into the first zone separately from one another.

Abstract: 1,2,6-Thiadiazine-3,5-dione-1,1-dioxides of the general formula ##STR1## wherein each R and R.sub.3 independently may be substituted or unsubstituted alkyl, alkenyl or substituted cycloalkyl are described. These compounds, as well as those wherein the R substituents additionally may be cycloalkyl or substituted or unsubstituted aryl, are useful as accelerators for the peroxidic polymerization of ethylenically unsaturated compounds, such as methacrylic acid compounds, and have particular utility in dental compositions.

Abstract: Impression materials based on cross-linked aziridino-polyester compounds which tend to adhere to the surface to be reproduced, are made nonadhesive by the addition of 1-15% by weight of oleic acid ethanolamide with respect to the aziridino-polyether component, and may thereafter be more easily and smoothly released from the object to be reproduced.

Abstract: 1,2,6-Thiadiazine-3,5-dione-1,1-dioxides of the general formula ##STR1## wherein each R and R.sub.3 independently may be substituted or unsubstituted alkyl, alkenyl or substituted cycloalkyl are described. These compounds, as well as those wherein the R substituents additionally may be cycloalkyl or substituted or unsubstituted aryl, are useful as accelerators for the peroxidic polymerization of ethylenically unsaturated compounds, such as methacrylic acid compounds, and have particular utility in dental compositions.

Abstract: The invention relates to the use of agglomerates of silicic acid having an average agglomerate size of 0.5 to 50 .mu.m, containing primary particles of silicic acid having an average particle size of 1 to 100 nm and serving as filler in dental materials on the basis of ethylenically unsaturated polymerizable monomers. This reinforcing filler is practically colorless and can be blended in considerable quantity into the polymerizable monomer material especially mono-functional and di-functional as well as polyfunctional esters of the acrylic acid and the methacrylic acid and yields a satisfactorily processable plastically deformable paste. If necessary, the agglomerated silicic acid is used together with non-agglomerated micro-fine silicic acid of an average particle size of 1 to 100 nm.

Abstract: A calcium aluminum fluorosilicate glass powder is disclosed which has average particle size of at least 0.5 microns, and is characterized in that the calcium in the surface of the powder's particles is depleted so that the quotient of the atomic ratio Si/Ca at the surface of the particles and the atomic ratio Si/Ca in the core region of the particles is at least 2.0, more preferably at least 3.0 and most preferably at least 4.0. The glass powder may be prepared by surface treating calcium aluminum fluorosilicate glass powder particles with an acid which forms calcium salts, washing the calcium salts off the treated particles and drying the washed particles.The glass powder has utility in self-hardening glass ionomer cements, such as dental or bone cements. Cements formed from the glass powder exhibit reduced periods of water sensitivity, while permitting sufficient time for processing.

Abstract: An improved opaque, photopolymerizable dental filling material is provided comprised of acrylic acid ester compounds containing mono and/or polyfunctional acrylic or methacrylic ester compounds, photoinitiators, pigments and possibly activators and silicon dioxide or silicate fillers, the improvement comprising the presence of finely divided calcium fluoride as a white pigment in a quantity of from 1-20 percent by weight. The presence of the calcium fluoride enables an opaque effect to be achieved without reducing the permeability of the filling material to polymerization radiation.

Abstract: Dental glass ionomer cements are obtained by using as a mixing component for preparing the final cement mixture either a liquid mixing component comprising an aqueous solution of a certain maleic acid-acrylic acid-copolymer and optionally usual additives or a solid, powdery mixing component comprising a powder mixture of a glass ionomer cement powder and the maleic acid-acrylic acid-copolymer in solid form and optionally usual additives.

Abstract: An improved photopolymerizable composition based on acrylic or methacrylic acid esters is disclosed. In addition to the mono- or polyfunctional acrylic or methacrylic acid ester compounds, an aliphatic, aromatic or mixed aliphatic-aromatic organic phosphite compound (in an amount of from about 0.1 to 20 percent by weight of the photopolymerizable ester compounds) and a monoketal of an aromatic 1,2-diketone compound (e.g., benzildimethylketal) are included as ultraviolet initiators to dramatically reduce the polymerization time of the composition without adversely affecting its stability.

Abstract: A novel process for the polymerization of aziridine compounds is disclosed. The polymerization process includes mixing an aziridine compound with a polymerization initiator having the formula: ##STR1## where R.sup.1 is an alkyl radical of 1 to 18 C atoms,R.sup.2 is an alkyl radical of 1 to 18 C atoms or a phenyl alkyl radical of 7 to 18 C atoms, wherein said alkyl radicals may contain an ester group and/or ether group, R.sup.3 and R.sup.4 are hydrogen, an alkyl radical of 1 to 18 C atoms, and/or an aryl radical which can be substituted with a chloro, nitro or alkoxy group, whereby the alkyl radicals of R.sup.3 and R.sup.4 together or in combination with B can form a cycloaliphatic or heterocyclic ring, B is an electron attracting radical, and A.sup..crclbar. is a non-nucleophilic anion.Polyimines are quickly formed at ambient temperature.

Abstract: An improved dental composition having shortened hardening time and after hardening increased compressive strength and abrasion resistance, including a radical-inducing compound and a polymerizable acrylic or methacrylic acid ester or diester compound with at least 20 percent by weight of the polymerizable compound being the diacrylic or dimethacrylic acid ester of bishydroxymethyltricyclo [5.2.1.0.sup.2,6 ]-decane. Other monofunctional or difunctional acrylic or methacrylic acid esters as well as fillers, pigments and stabilizers can be included.

Abstract: An improved process for the photopolymerization of compositions including photopolymerizable acrylic or methacrylic acid esters and an initiator (e.g., a benzoin compound) is disclosed. The addition of 0.1 to 20 weight percent (based on the amount of polymerizable material) of an organic phosphite substantially reduces the polymerization time of the resulting composition.

Abstract: An improvement in the redox polymerization of unsaturated compounds, e.g., acrylic or methacrylic acids or their ester derivatives, using novel accelerators is disclosed. The polymerization is performed utilizing as the accelerator N,N-bis-hydroxyalkyl-3,5-di-t-butyl anilines having the structural formula ##STR1## wherein R.sub.1 and R.sub.2 are the same or different and are H or a lower alkyl group having 1 to 4 carbon atoms. The resulting polymers are highly resistant to discoloration.

Abstract: Novel bromine-containing compounds of the formula ##STR1## in which R is an alkylidene radical having 1 to 6 carbon atoms, a cycloalkylidene radical or a SO.sub.2 radical, R' is an alkylene radical having 2 to 6 carbon atoms or a cycloalkylene radical and Y is an acyl radical of a carboxylic acid having 2 to 6 carbon atoms and optionally bearing an aromatic substituent, and x is 1 or 2 and y is 0, 1 or 2, which are particularly useful for the preparation of dental replacement parts and dental models when mixed with a substance that catalyzes the polymerization of the compounds.

Abstract: Compositions, which may be mixed with water to prepare a dental silicate cement, consist essentially of a silicate glass powder and a solid polymeric material selected of polymers of unsaturated .alpha.,.beta.-dicarboxylic acids.

Abstract: Superior artificial teeth, dentures, other dental replacement parts and dental prosthetic articles and devices, which exhibit high abrasion resistance, stability to moisture and which do not undergo volume changes, are obtained by polymerization of a compound of the formula ##STR1## in which R is H or -CH.sub.3, X is an alkylidene or the -SO.sub.2 -group, Y is an oxyalkylene group having between 2 and 5 carbon atoms, or an alkylidene group having between 1 and 5 carbon atoms. In some instances, the polymerization is carried out in the presence of a filler.

Abstract: To provide properly layered windings on a rotating spool, for example on a flanged spool carrier, the material is guided towards the spool at a predetermined angle of attitude, so that the windings on the spool body fall adjacent each other; the traverse of the spool with respect to the material supply position is so controlled, by means of an electronic control system, considering the width of the spool, the thickness of the material and winding speed, that the material will be wound on the spool pressed against the next previously applied winding and, at the end layers, the relative traverse speed (for example by axial shift of the winding spindle) is so controlled that, just before and after the formation of superimposed windings, the attitude angle of the supplied material will tend to become zero and then, after formation of a new winding layer, the attitude angle will reach the predetermined value.