Dental filling composition utilizing zinc-containing inorganic filler

Abstract

This invention is a dental filling composition for making dental restorations. More particularly, the invention provides a radiopaque dental filling material. Specifically, the dental filling material contains a zinc-containing glass as the component imparting opacity to X-rays.

I claim: 
     
       1. A dental filling composition comprising a polymerizable resin binder and a finely divided inorganic glass filler which is X-ray opaque and single phase, wherein said X-ray opaque inorganic glass filler consists essentially of, in percent by weight:   ______________________________________                                    
Zinc oxide            20 to 35%                                           
Silica                45 to 65%                                           
Boric oxide           3 to 15%                                            
Aluminum oxide        0 to 10%                                            
Aluminum fluoride     At least 2%                                         
Alkali metal oxide or 0 to 3%                                             
alkaline earth metal                                                      
oxide                                                                     
______________________________________                                    
     wherein the compound weight of aluminum oxide and aluminum fluoride is at least about 10%, and wherein said glass exhibits an X-ray absorption characteristic of at least 1/16 inch.   
     
     
       2. A composition in accordance with claim 1, wherein said binder comprises a free-radically polymerizable resin. 
     
     
       3. A composition in accordance with claim 2, wherein said polymerizable resin binder comprises BIS-GMA. 
     
     
       4. A composition in accordance with claim 1, wherein the index of refraction of said glass filler and said resin are substantially the same. 
     
     
       5. A composition in accordance with claim 1, wherein said composition is in the form of two pastes, the first said paste comprising polymerizable resin binder, inorganic glass filler, and a catalyst, and the second said paste comprising polymerizable resin binder, inorganic glass filler, and an accelerator. 
     
     
       6. A composition in accordance with claim 5, wherein said filler represents at least about 70% by weight of each said paste. 
     
     
       7. A composition in accordance with claim 5, wherein said binder in each said paste comprises BIS-GMA. 
     
     
       8. A composition in accordance with claim 3, wherein said glass filler consists essentially of, in percent by weight:   ______________________________________                                    
Zinc oxide       25 to 28%                                                
Silica           46 to 48%                                                
Boric oxide      6 to 9%                                                  
Aluminum oxide   1 to 3%                                                  
Aluminum fluoride                                                         
                 17 to 19%                                                
______________________________________                                    
     wherein the combined weight of aluminum oxide and aluminum floride is not greater than about 20%. .Iadd.9. A dental filling composition comprising a polymerizable resin binder and a finely divided inorganic glass filler which is X-ray opaque and single phase, wherein said X-ray opaque inorganic glass filler consists essentially of, in percent by weight:     ______________________________________                                    
 .Iadd.Zinc oxide        20 to 35%                                        
Silica                   45 to 65%                                        
Boric oxide               3 to 15%                                        
Aluminum oxide           combined weight of                               
                         at least about 10%                               
Aluminum fluoride                                                         
Alkali metal oxide or    0 to 5%                                          
alkaline earth metal                                                      
oxide                                                                     
______________________________________                                    
.Iaddend.
     wherein the weight of aluminum floride is sufficient to contribute to the melt fluidity of the glass and enable it to be poured in the form of thin filaments for rapid cooling thereof, and wherein said glass exhibits an X-ray absorption characteristic of at least 1/16 inch.  .Iadd.10. A composition in accordance with claim 9, wherein said combined weight of aluminum oxide and aluminum fluoride is not greater than about 20%. .Iaddend. .Iadd.11. A composition in accordance with claim 9, wherein said binder comprises a free-radically polymerizable resin. .Iaddend. .Iadd.12. A composition in accordance with claim 11, wherein said polymerizable resin binder comprises BIS-GMA. .Iaddend. .Iadd.13. A composition in accordance with claim 9, wherein the index of refraction of said glass   
     
     
        filler and said resin are substantially the same. .Iaddend. .Iadd.14.  A composition in accordance with claim 9, wherein said filler comprises 80-90% of the weight of said composition. .Iaddend. .Iadd.15. A dental filling composition comprising a polymerizable resin binder and a finely divided inorganic glass filler which is X-ray opaque and single phase, wherein said X-ray opaque inorganic glass filler consists essentially of, in percent by weight:   ______________________________________                                    
.Iadd.Zinc oxide 20 to 35%                                                
Silica           45 to 65%                                                
Boric oxide       3 to 15%                                                
Aluminum oxide    0 to 10%                                                
Alkali metal oxide or                                                     
                 0 to 5%                                                  
alkaline earth metal                                                      
oxide                                                                     
______________________________________                                    
.Iaddend.
     and aluminum fluoride, wherein the combined weight of aluminum oxide and aluminum fluoride is at least about 10%, the weight of aluminum oxide is sufficient to contribute to the melt fluidity of the glass and enable it to be poured in the form of thin filaments for rapid cooling thereof, and said glass exhibits an X-ray absorption characteristic of at least 1/16 inch.  .Iadd.16. A composition in accordance with claim 15, wherein said combined weight of aluminum oxide and aluminum fluoride is not greater than about 20%. .Iaddend. .Iadd.17. A composition in accordance with claim 15, wherein said binder comprises a free-radically polymerizable resin. .Iaddend. .Iadd.18. A composition in accordance with claim 17, wherein said polymerizable resin binder comprises BIS-GMA. .Iaddend. .Iadd.19. A composition in accordance with claim 15, wherein the index of refraction of said glass filler and said resin are substantially the same. .Iaddend. .Iadd.20. A composition in accordance with claim 15, wherein said filler comprises 80-90% of the weight of said composition. .Iaddend.