Abstract
A method of machining a dental block (2) by using at least one dental tool (4) to finish or pre-finish a dental restoration (5) at least completely along the equator (5a) with or without a holding stub (5b). The method includes: a step of moving the axis (4a) of the dental tool (4) along a path (6) with an overlaid lateral motion having an amplitude (A), and without separating an unmachined piece (2″) from the rest of the dental block (2). The path (6) lies away from the equator (5a) at least by an amount equal to half of the diameter of the dental tool (4) plus half of the amplitude (A) of the overlaid lateral motion.
Claims
1. A computer-implemented method comprising: machining a dental block by using at least one dental toot to finish or pre-finish a dental restoration at least completely along an equator, with or without a holding stub, the method further comprising a step of moving an axis of the dental tool along a path with an overlaid lateral motion having an amplitude (A), and without separating an unmachined piece from a rest of the dental block, wherein the path lies away from the equator at least by an amount equal to half of the diameter of the dental tool plus half of the amplitude (A) of the overlaid lateral motion.
2. The method according to claim 1, further comprising: moving dental tool at most one revolution around the equator to finish or pre-finish the dental restoration at least completely along the equator, with or without a holding stub.
3. The method according to claim 1, further comprising: moving the dental tool more than one revolution around the equator to finish or pre-finish the dental restoration at least completely along the equator, with or without a holding stub.
4. The method according to claim 1, wherein the amplitude (A) of the overlaid lateral motion is kept constant or varied along the path.
5. The method according to claim wherein the path has a trochoidal shape.
6. The method according to claim 1, wherein two dental tools are used for machining the dental block, wherein the axes, of the two dental tools are aligned parallelly m opposite direction (z) and moved either simultaneously or sequentially along the corresponding paths to finish or pre-finish the dental restoration at least completely along the equator, with or without a holding stub.
7. The method according to claim wherein the lateral surface of at least one dental tool is used for machining the dental block, wherein the axis of the dental tool is penetrated through the entire dental block, or only in a part of the dental block.
8. The method according to claim 1, wherein each dental tool is one of a cylindrical shaped tool with or without a corner radius, a spherical shaped tool, a torical shaped tool, a conical shaped tool, a milling tool with defined cutting edges, or a grinding tool with undefined cutting edges or a tool haying a combined shape of one or more of the preceding tools.
9. The method according to claim 1, wherein the dental block is made of a material comprising ceramic, pre-sintered ceramic, metal, pre-sintered metal, plastic, and/or a composite.
10. A computer-program comprising computer-readable codes for causing a computer-based dental machine system to execute the method steps according to claim 1.
11. A non-transitory computer-readable storage medium storing a program which when executed by a computer system causes the computer system to perform the method steps as defined in claim 1.
12. A dental machining system comprising: a dental tool machine which comprises: one or more carriage units each configured to movably hold at least one dental tool for machining a corresponding side of the dental block; a holding unit configured to hold at least one dental block relatively movably with respect to the dental tools; and a control unit having a computer-program configured to individually control drive of the carriage units and the holding unit according to the method defined in claim 1.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] In the subsequent description, further aspects and advantageous effects of the present invention will be described in more detail by using exemplary embodiments and by reference to the drawings, wherein
[0025] FIG. 1—is a dental block according to an embodiment of the present invention, wherein the dashed lines show a dental restoration to be machined from the dental block with the dental tool machine in FIG. 9;
[0026] FIG. 2—is the dental restoration machined from the dental block of FIG. 1 through a method according to an embodiment of the present invention;
[0027] FIG. 3—is a schematic view of a machining path (i.e., the meandering line) according to the prior art for machining the equator of a dental restoration (dashed lines) from a dental block;
[0028] FIG. 4—is a schematic view of another machining path (i.e., the bold line) according to the prior art for machining the equator of a dental restoration (dashed lines) from a dental block;
[0029] FIG. 5—is a schematic view of a machining method according to a first embodiment of the present invention for machining the dental block along the equator of the dental restoration (dashed lines) in a single machining step, wherein the arrows show the varying amplitude of the overlaid lateral motion of the dental tool axis;
[0030] FIG. 6 to FIG. 8—are schematic views of another machining method according to a second embodiment of the present invention for machining the dental block along the equator of the dental restoration (dashed lines) in two machining steps, wherein the arrows show the substantially constant amplitude of the overlaid lateral motion of the dental tool axis;
[0031] FIG. 9—is a partial perspective view of a dental machining system according to an embodiment of the present invention for machining the dental block of FIG. 1.
[0032] The reference numbers shown in the drawings denote the elements as listed below and will be referred to in the subsequent description of the exemplary embodiments: [0033] 1. Dental tool machine [0034] 2. Dental block [0035] 2′ Corner piece [0036] 2a. Shaft [0037] 2b. Channel [0038] 3. Carriage unit [0039] 3a. Arm [0040] 3b. Shaft [0041] 4. Dental tool [0042] 4a. Axis [0043] 5. Dental restoration [0044] 5a. Equator [0045] 5b. Stub [0046] 6. Path
[0047] A: Amplitude of the overlaid lateral motion
[0048] FIG. 9 illustrates part of a dental machining system according to an embodiment of the present invention. The dental machining system has a double-spindle dental tool machine (1). The dental tool machine (1) has two carriage units (3) each movably holding a dental tool (4) for machining a corresponding side of the dental block (2); a holding unit (not shown) for holding a dental block (2) relatively movably with respect to the dental tools (4); and a control unit adapted to individually control drive of the carriage units (3) and the holding unit according to the machining method of the present invention. The machining method will be described later in the subsequent description. Each carriage unit (3) has an arm (3a) which is connected to a respective shaft (3b). Each shaft (3b) can be rotated around the z-axis and translated along the z-axis by means of a respective driving mechanism (not shown) of the carriage unit (3). The axes (4a) of the two dental tools (4) are aligned parallelly in opposite directions (z). Each dental tool (4) is mountable to a respective tool motor (not shown) in the respective arm (3a). The dental tool (4) may be one of a cylindrical shaped tool (4) with or without a corner radius, a spherical shaped tool (4), a torical shaped tool (4), a conical shaped tool (4), a milling tool (4) with defined cutting edges, or a grinding tool (4) with undefined cutting edges or a tool (4) having a combined shape of one or more of the preceding tools (4). The dental block (2) is connected via the holding unit to a shaft (2a). The dental block (2) may be made of a material which includes ceramic, pre-sintered ceramic, metal, pre-sintered metal, plastic, or a composite. The shaft (2a) for the dental block (2) can be rotated around the y-axis and translated along the y-axis by means of a respective driving mechanism (not shown).
[0049] FIG. 1 shows an enlarged view of a dental block (2) according to an embodiment of the present invention. The dental block (2) may be rectangular shaped or alternatively round shaped. The dashed lines in FIG. 1, illustrate a dental restoration (5) to be machined from the dental block (2) with the dental tool machine (1) in FIG. 9. FIG. 2 shows the enlarged view of the dental restoration (5) machined from the dental block (2) in FIG. 1 through the machining method according to an embodiment of the present invention. In the method of machining the dental block (2), at least one dental tool (4) is used to finish or pre-finish the dental restoration (5), at least completely along the equator (5a), with or without a holding stub (5b).
[0050] According to the present invention, the machining of the dental block (2) may be carried out either in a single machining step or in multiple machining steps to finish or pre-finish the dental restoration (5) at least completely around the equator (5a), with or without a holding stub (5b).
[0051] FIG. 5 illustrates the machining method according to a first embodiment of the present invention in which a single machining step is carried out. As shown in FIG. 5, the axis (4a) of the dental tool (4) is moved along a path (6) with an overlaid lateral motion having an amplitude (A), and without separating an unmachined piece (2′) from the rest of the dental block (2). The path (6) lies away from the equator (5a) by an amount equal to half of the diameter of the dental tool (4) plus half of the amplitude (A) of the overlaid lateral motion. The amplitude (A) is varied along the path (6) such that the rest of the dental block (2) around the equator (5a) of the dental restoration (5) is completely removed except for the holding stub (5b). FIG. 2 shows the dental block (2) after the single machining step is completed.
[0052] For ease of description, the multi-step machining will be explained for the case where two machining steps are carried out sequentially. FIG. 6 to FIG. 8 illustrate the machining method according to a second embodiment of the present invention in which two machining steps are sequentially carried out. FIG. 6 shows the first machining step. As shown in FIG. 6, the axis (4a) of the dental tool (4) is moved along a path (6) with an overlaid lateral motion having an amplitude (A), without separating an unmachined piece (2′) from the rest of the dental block (2). The path (6) lies away from the equator (5a) at least by an amount equal to half of the diameter of the dental tool (4) plus half of the amplitude (A) of the overlaid lateral motion. The amplitude (A) is kept substantially constant along the path (6). FIG. 7 shows the dental block (2) after the first machining step is completed. As shown in FIG. 7, the rest of the dental block (2) around the equator (5a) of the dental restoration (5) is completely removed only in three sections of the dental block (2). FIG. 8 shows the second machining step. As shown in FIG. 8, the axis (4a) of the dental tool (4) is moved along a path (6) with the same overlaid lateral motion having the amplitude (A), without separating an unmachined piece (2′) from the rest of the dental block (2). The path (6) lies away from the equator (5a) at least by an amount equal to half of the diameter of the dental tool (4) plus half of the amplitude (A) of the overlaid lateral motion. The amplitude (A) is kept substantially constant along the path (6). FIG. 2 shows the dental block (2) after the second machining step is completed. As shown in FIG. 2, after the second machining step, the rest of the dental block (2) around the equator (5a) of the dental restoration (5) becomes completely removed except for the holding stub (5b).
