- An opening device (10; 10') for a sealed package containing a pourable product, said opening device (10; 10') defining an axis and comprising: - a frame configured to be fitted in use about a pierceable portion of said package and defining a pour opening for the pourable product, which is coaxial with said axis; - a cap which is coaxially fitted in use onto said frame to close said pour opening; - a tubular cutter (6; 6') engaging said pour opening coaxially with said axis and movable in use with respect to said frame to cut said pierceable portion; and - cutting means (8; 8') which protrude from one axial end of said tubular cutter (6; 6') and which cooperate, in use, with said pierceable portion to unseal said package; said cutting means (8; 8') comprising at least one tooth (23, 24, 25; 23', 24', 25') having: - a first cutting face and a second cutting face, which extend transversally to said axis and converge towards a free end of said tooth (23, 24, 25; 23', 24' 25'); - at least one third cutting face (30; 30'), which is circumferentially interposed between said first cutting face and said second cutting face and which extends transversally to the first cutting face and the second cutting face; - a first edge (31; 31'), which is arranged between said third cutting face (30; 30') and said first cutting face; and - a second edge (32; 32'), which is arranged between said third cutting face (30; 30') and said second cutting face; wherein the tubular cutter (6; 6') comprises an inner surface and an outer surface, which are radially opposite to each other with respect to said axis; wherein the tooth (23, 24, 25; 23', 24' 25') further comprises a third edge (35; 35'); characterized in that the third edge (35; 35') is arranged between the third cutting face (30; 30') and the outer surface, wherein, when the tubular cutter (6; 6') interacts with the pierceable portion, the third cutting face (30; 30') performs the cutting action and the third edge (35; 35') at least partly contributes to cut the pierceable portion. - a frame configured to be fitted in use about a pierceable portion of said package and defining a pour opening for the pourable product, which is coaxial with said axis; - a cap which is coaxially fitted in use onto said frame to close said pour opening; - a tubular cutter (6; 6') engaging said pour opening coaxially with said axis and movable in use with respect to said frame to cut said pierceable portion; and - cutting means (8; 8') which protrude from one axial end of said tubular cutter (6; 6') and which cooperate, in use, with said pierceable portion to unseal said package; - a first cutting face and a second cutting face, which extend transversally to said axis and converge towards a free end of said tooth (23, 24, 25; 23', 24' 25'); - at least one third cutting face (30; 30'), which is circumferentially interposed between said first cutting face and said second cutting face and which extends transversally to the first cutting face and the second cutting face; - a first edge (31; 31'), which is arranged between said third cutting face (30; 30') and said first cutting face; and - a second edge (32; 32'), which is arranged between said third cutting face (30; 30') and said second cutting face; wherein the tubular cutter (6; 6') comprises an inner surface and an outer surface, which are radially opposite to each other with respect to said axis; wherein the tooth (23, 24, 25; 23', 24' 25') further comprises a third edge (35; 35'); characterized in that the third edge (35; 35') is arranged between the third cutting face (30; 30') and the outer surface, wherein, when the tubular cutter (6; 6') interacts with the pierceable portion, the third cutting face (30; 30') performs the cutting action and the third edge (35; 35') at least partly contributes to cut the pierceable portion.