Title of Invention	A RADIOPAQUE GLASS POWDER FOR USE IN DENTAL COMPOSITES
Abstract	A radiopaque glass powder for use In dental composnes comprising 45 to 65 parts by weight of silica, 15 to 35 parts by weight of boron oxide, 5 to 15 parts by weight of boron trioxide and 5 to 15 parts by weight of alumina.

Full Text

FIE D OF THE INVENTION This invention relates to radiopaque glass filler and a process for the preparation thereof This invention further relies to radiopaque glass fillers for use in dental composites to induce radiopacity. BACKGROUND OF THE INVENTION Currently, filler materials which induce radiopacity to hiotnaterials including dental materials are not available in India The price of imported radiopaque fillers which are currently in use in radiopaque composites is very high. OBJECTS Of THE INVENTION It is therefore an object of this invention to propose a radiopaque glass filler which may be prepared from indigenous products and is therefore cheap. It is a further object of this invention to propose a radiopaque gia>;s tiller possessing a high compressive strength-, diametral tensile strength, ttexurai sorption value. These and other objects and advantages of this invention will be apparent from the ensuing descriptioa BRIEF DESCRIPTION OP THE INVENTION Thus according to this invention is provided a radiopaque glass powder for use in dental composites comprising one or more oxides of metals selected from silicon,, boron, barmm and aluminium. According to this invention is further provided a method for the preparation of a radiopaque glass filler. In accordance with this invention, the glass filler comprises 45 to 65 parts by weight of silica, 15 to 35 parts by weight of barium oxide, 5 to 15 parts by weight of boron trioxide and 5 to 15 parts by. weight of alumina The mixture is heated for 1 to 2 hrs. at a temperafur& HI the range of 1400 to I600°C in a muffle furnace* ami quenched in distilled water for a period of 15 to 30 mins,. The glass granules thus obtained are powdered into smaller particles in a zirconia grinding cup upto In u further embodiment of this invention* the glass filler is used for the preparation of a dental paste for preparing a dental filling cement for instant application. In accordance with the further embodiment of this invention* the glass filler is heated with a silaue coupling agent such as trimethoxypropyl silyl methaciylate before being mixed with a thinned oligomer consisting of Bisphenol A-glycidyl methacrylate resin and diluents such as Methylene glycol dimethacrylate to form a high viscosity paste. The paste contains additives such as photoinitiator, inhibitors and activators* in addition to the thinned oligomer. The mixing is earned out at room temperature. The coupling agent is used in amounts of 0,5 to 15%. The photoinitiator used is a diketone such as camphorquinone which is used in an amount of 0.1 to 1% by weight of the thinned oligomer. TTie inhibitor which also includes UV stabilisers is selected from butylated hydroxy toluene and is used in 10 to 1000 ppm based on the weight of the oligomer. The UV stabiliser is selected from phenyl salicylate in combination with/without 2-hydroxy 4-ruethoxy benzophenone. The activator is selected from tertiary amines such as dimethyl p-toluidine or dimethyl amino phenethyl alcohol or diethyl p-toluidine The activator is used in amounts of 0.1 to 1% by weight of the thinned oligomer Ihe paste thus obtained cures into a hard solid when exposed to a visible light of 440-480 am wavelength for J 0-30 sees, and the cured material rs found to be radiopaque when exposed to dental X-ray*;. The radiopaque paate ibrmulufiona using this filler has been studied for its curing characteristics* water sorption, mechanical properties such as compressive strength, diametral tensile strength and transverse strength. All the properties were comparable with control imported materials and much above the minimum requirements stipulated by the International specifications. The radiopaque nature of the cured composite has been determined using dental X-ray» and compared wife control. Hie invention will now be explained in greater detail wife help of the following non-limiting example, 70 parts by weight of a dinKthacrylatc such as BisphcnoJ A-Glycidyl diraethacrylate (B1S-GMA) is mixed with 30 parts by weight of a low molecular weight dimethacrylate such as ethylene glycol dunethacrylate(£GDMA) or triethyleneglycol dimethacrylate (TEGDMA) in order to decrease the viscosity and increase the flow character of the B1S-GMA. A photoinitiator such as (-)Camphorquinone (CQ, 0.25%), a tertiary amine activator such as dimethyl p-toiuidine (DMPT) or dimethylamino pbencthyl alcohol (DMAPE A. 0.5%), 0-04 to 0.1 % of stabilisers and inhibitors such as butylatcd hydroxyl toluene (BHT), $ak>l and UV-9 are also added and mixed with the parent resin mixture. 100 parts of the above resin mixture is further mixed with 400-440 parts by weight of sijgjated radiopaque glass filler having a compositioo.of SiCh 55, BaO 25, B2Oj 10 and AJbOj-10 and 12 parts by weight of pyrogenic silica filler to form a paste of appropriate viscosity. This paste cures into a hard solid when exposed to a light source of 440-480 nm wavelength within 10*30 sees. 1. A radiopaque glass powder for use in dental composites comprising one or more oxides of metals selected from silicon, boron, barium and aluminum. 2. The glass powder as claimed in claim 1, comprising 45 to 65 parts by weight of silica, 15 to 35 parts by weight of baron oxide, 5 to 15 parts by weight of baron trtoxlde and 5 to 15 parts by weight of alumina. 3. A process for preparing the radiopaque glass powder as claimed in claim 1, comprising the steps of heating a mixture containing 45 to 65 parts by weight of silica, 15 to 35 parts by weight of barium oxide, 5 to 15 parts by weight of boron trfoxlde and 5 to 15 parts by weight of alumina at a temperature in the range of 1400 to 1600°C for 1 to 2 hours to obtain a mixture followed by quenching the mixture to obtain granules and grinding the granules to obtain the radiopaque glass powder, 4. The process as claimed in claim 3 wherein the mixture is heated in a muffle furnace, 5. The process as claimed in claim 3 wherein the heated mixture is quenched in distilled water. 6. The process as claimed in claim 3 wherein the granules are ground in a zirconia grinding cup upto 7. A process preparation of a dental paste comprising treating the radiopaque glass powder with a coupling agent to obtain a mixture, followed by adding the mixture to a thinned oligomer to form the dental paste. 8. The process as claimed in claim 7, wherein said dental paste contains additives such as photoinltlators, Inhibitors and activators. 9. The process as claimed in claim 7r wherein the coupling agent is a saline coupling agent such as for e.g. trimetho*ypropyl siiyl methacrylate. 10. The process as claimed in claims 7 & 8 wherein said photoinitiator is a diketone. 11. The process as claimed in claim 7, wherein said oligomer is Bisphenoi A-glycidy methacrylate resin 12. The process as claimed in claim 7', wherein said oligomers is thinned with diluents such as for e.g. triethylene glycol dimethacrylate, 13. The process as claimed fa efaims 7&8r wherein said inhibitor is selected from butylated hydroxy toluene. 14. The process as claimed in claims 7&8, wherein safd inhibitor includes UV stabilizers setected from phenyl salicylate and optionally 2-hydroxy 4-methoxy benzophenone. 15. The process as claimed In claims 7&8, wherein the activator Is selector from teritiary amines, 16. The process as claimed in claims 7&8, wherein said coupling agent is used in amounts of 0.5 to 1,5%. 17. The process as claimed in claims 7&8, wherein said photoinitiator is used in amounts of 0.1 to 1% by weight of the thinned oligomer. 18. The process as claimed in claims 7&8, wherein said inhibitor is used in 10 to 1000 ppm based on the weight of the oligomer. 19. The process as claimed in claims 7&8, wherein said activator is used in amounts of 0.1 to 1% by weight of the thinned oligomer. 20. The process as claimed in claims 7&8, wherein the mixing is carried out at room temperature. 21. A dental paste for preparing dental filling cement and comprising a radiopaque glass powder, coupling agent, a thinned oligomer and optional additives, such as photGlnitiators, inhibitors and activators. 22. The radiopaque glass powder substantially as herein described. 23. The process for the preparation of the radiopaque glass powder substantially as herein described. 24. The dental paste substantially as herein described. 25. The process for preparing the dental paste substantially as herein described.

Documents:

772-mas-2002-abstract.pdf

772-mas-2002-claims filed.pdf

772-mas-2002-claims granted.pdf

772-mas-2002-correspondnece-others.pdf

772-mas-2002-correspondnece-po.pdf

772-mas-2002-description(complete)filed.pdf

772-mas-2002-description(complete)granted.pdf

772-mas-2002-form 1.pdf

772-mas-2002-form 19.pdf

772-mas-2002-form 3.pdf