Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C13/00—Dental prostheses; Making same
  • A61C13/0003—Making bridge-work, inlays, implants or the like
  • A61C13/0006—Production methods
  • A61C13/0018—Production methods using laser
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C8/00—Means to be fixed to the jaw-bone for consolidating natural teeth or for fixing dental prostheses thereon; Dental implants; Implanting tools
  • A61C8/0012—Means to be fixed to the jaw-bone for consolidating natural teeth or for fixing dental prostheses thereon; Dental implants; Implanting tools characterised by the material or composition, e.g. ceramics, surface layer, metal alloy
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
  • B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
  • B23K26/062—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam
  • B23K26/0622—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam by shaping pulses
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/08—Devices involving relative movement between laser beam and workpiece
  • B23K26/082—Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/08—Devices involving relative movement between laser beam and workpiece
  • B23K26/0823—Devices involving rotation of the workpiece
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/08—Devices involving relative movement between laser beam and workpiece
  • B23K26/083—Devices involving movement of the workpiece in at least one axial direction
  • B23K26/0853—Devices involving movement of the workpiece in at least in two axial directions, e.g. in a plane
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/08—Devices involving relative movement between laser beam and workpiece
  • B23K26/0869—Devices involving movement of the laser head in at least one axial direction
  • B23K26/0876—Devices involving movement of the laser head in at least one axial direction in at least two axial directions
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/12—Working by laser beam, e.g. welding, cutting or boring in a special atmosphere, e.g. in an enclosure
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/12—Working by laser beam, e.g. welding, cutting or boring in a special atmosphere, e.g. in an enclosure
  • B23K26/1224—Working by laser beam, e.g. welding, cutting or boring in a special atmosphere, e.g. in an enclosure in vacuum
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/12—Working by laser beam, e.g. welding, cutting or boring in a special atmosphere, e.g. in an enclosure
  • B23K26/123—Working by laser beam, e.g. welding, cutting or boring in a special atmosphere, e.g. in an enclosure in an atmosphere of particular gases
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/352—Working by laser beam, e.g. welding, cutting or boring for surface treatment
  • B23K26/3568—Modifying rugosity
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/36—Removing material
  • B23K26/38—Removing material by boring or cutting
  • B23K26/382—Removing material by boring or cutting by boring
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/36—Removing material
  • B23K26/38—Removing material by boring or cutting
  • B23K26/382—Removing material by boring or cutting by boring
  • B23K26/389—Removing material by boring or cutting by boring of fluid openings, e.g. nozzles, jets
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/36—Removing material
  • B23K26/40—Removing material taking account of the properties of the material involved
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C8/00—Means to be fixed to the jaw-bone for consolidating natural teeth or for fixing dental prostheses thereon; Dental implants; Implanting tools
  • A61C8/0018—Means to be fixed to the jaw-bone for consolidating natural teeth or for fixing dental prostheses thereon; Dental implants; Implanting tools characterised by the shape
  • A61C8/0037—Details of the shape
  • A61C2008/0046—Textured surface, e.g. roughness, microstructure
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2/30767—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
  • A61F2/30771—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth applied in original prostheses, e.g. holes or grooves
  • A61F2002/30795—Blind bores, e.g. of circular cross-section
  • A61F2002/30807—Plurality of blind bores
  • A61F2002/30808—Plurality of blind bores parallel
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2/30767—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
  • A61F2/30771—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth applied in original prostheses, e.g. holes or grooves
  • A61F2002/30838—Microstructures
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2/30767—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
  • A61F2/30771—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth applied in original prostheses, e.g. holes or grooves
  • A61F2002/3085—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth applied in original prostheses, e.g. holes or grooves with a threaded, e.g. self-tapping, bone-engaging surface, e.g. external surface
  • A61F2002/30871—Trapezoidal threads
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2/3094—Designing or manufacturing processes
  • A61F2002/3097—Designing or manufacturing processes using laser
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2310/00—Prostheses classified in A61F2/28 or A61F2/30 - A61F2/44 being constructed from or coated with a particular material
  • A61F2310/00005—The prosthesis being constructed from a particular material
  • A61F2310/00011—Metals or alloys
  • A61F2310/00023—Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K2103/00—Materials to be soldered, welded or cut
  • B23K2103/08—Non-ferrous metals or alloys
  • B23K2103/14—Titanium or alloys thereof
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K2103/00—Materials to be soldered, welded or cut
  • B23K2103/50—Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26

Definitions

• the present invention relates to a method for laser treatment of implantable devices, to implantable devices obtained using said method, as well as to a laser system for laser treatment of implantable devices.
• the surface microtopography of the implant influences adhesion, proliferation, growth, migration, orientation, and differentiation of the cells of the host tissue.
• micromachined surfaces characterized by a control of the surface structure that is more precise than what is allowed by currently adopted techniques of surface roughening (sanding, mordanting, plasma spraying) , improve and accelerate integration of a medical device in the surrounding tissue.
• the aim of the present invention is to provide a method of laser treatment that will enable a surface with repeatable and controlled morphological characteristics to be obtained at a micrometric level on the implantable device, said method being able to optimize the response of the surrounding tissue to the device, without introducing at the same time any chemical contamination.
• a further aim of the present invention is, at the same time, to obtain a high speed of process and hence a high productivity.
• the aforesaid aim is achieved by a method of laser treatment of an implantable device comprising the steps of:
• DPSS diode-pumped solid-state
• the present invention likewise regards a laser system for the treatment of an implantable device for creating on said device a surface morphology comprising a controlled distribution of pores, said system being characterized in that it comprises a diode-pumped solid-state (DPSS) generator in Q-switch regime for generating a pulsed laser beam of a power such as to obtain pores having a diameter of between 3 and 150 ⁇ m, means for focusing the laser beam on a surface of the device, relative movement means for displacing the laser beam with respect to said surface to create a relative motion of scanning of said surface by means of said laser beam, and means for controlling said relative movement means for creating a scanning motion such as to produce pores with a pitch of between 3 and 300 ⁇ m.
• the present invention moreover regards an implantable device comprising a surface provided with a controlled distribution of pores having a diameter and depth of between 3 and 150 ⁇ m and a pitch of between 3 and 300 ⁇ m.
• FIG. 1 is a schematic view in elevation of an endosseous implant performed according to the present invention
• FIG. 2 is a schematic illustration of a portion of surface of the implant
• FIG. 6 and 7 are two diagrams of laser systems for the treatment of endosseous implants according to the present invention.
• - Figure 8 is a graph that presents the results of an in-vitro test of cell proliferation and differentiation on substrates having different surface finishing
• - Figures 9 is an enlarged image of an in-vivo implant in the femur of a rabbit, with a machined smooth surface (comparative example) ;
• FIGS 10, 11 and 12 are enlarged images of in-vivo implants in the femur of a rabbit, with laser-treated surface.
• an endosseous implant in particular a dental implant.
• the implant 1 illustrated purely by way of example, comprises a threaded stem 2 and a substantially cylindrical or slightly conical head 3 and is provided with a threaded axial internal seat 4, axially open on the side of the head 3, for connection of a prosthetic element.
• the implant 1 is designed to be inserted in an implantation site obtained by surgery in a mandibular or maxillar bone of the patient, and is made of commercially pure titanium or else a biocompatible metal alloy, for example a titanium alloy.
• the side surface 4 of the implant 1 has surface microholes or pores 5 obtained by means of laser treatment.
• the pores 5 are arranged in a plurality of rows 6 set alongside ' one another and at equal distances apart from one another.
• the rows can present a rectilinear or preferably helical pattern, as is described in greater detail in what follows.
• the pores can present a square-matrix arrangement, a honeycomb arrangement, or some other configuration.
• the diameter and depth of the pores are between 3 and 150 ⁇ m, preferably between 3 and 30 ⁇ m, and even more preferably between 5 and 20 ⁇ m.
• the average pitch between adjacent pores is 3-300 ⁇ m, preferably 5-150 ⁇ m, and even more preferably 10- 30 ⁇ m.
• the experimental materials were constituted by sterile cylinders made of commercially pure titanium of the same degree as that of the implants, having a diameter of 4 mm and a length of 13 mm.
• the cells used for the adhesion test were of an osteoblastic type of the cell line SaOS-2.
• the SaOS-2 cells are of a continuous tumoural cell line, phenotypically stable and homogeneous human osteosarcoma, which are easy to cultivate and propagate and are able in any case to express many of the properties of non-transformed osteoblasts.
• a suspension of 1.25 x 10 4 SaOS-2 cells in 2.5 ml of McCoy's culture medium with the addition of 15% of bovine foetal serum, L-glutamin, penicillin, streptomycin and amphotericin B was introduced into sterile containers made of polystyrene with twelve compartments. Simultaneously also the cylinders to be tested were introduced, after being extracted from the sterile pack under the laminar-flow hood. The containers were then put to incubate at 37 0 C, 5% CO 2 and relative humidity of 98% for ⁇ hours and 24 hours.
• the SaOS-2 cells in contact with the specimens were observed at the inverse optical microscope to verify the absence of cytotoxic effects that would invalidate the result.
• the specimens were washed with Dulbecco' s phosphate buffered saline (DPBS) in order to remove the non-adherent cells, and subjected to fixation and to all the procedures necessary for subsequent observation at the electronic microscope.
• DPBS Dulbecco' s phosphate buffered saline
• the surface presented numerous cells already with flattened shape tending to reproduce the underlying surface, together with cells with a more rounded morphology typical of the cells in suspension.
• the body of the cells during flattening frequently showed numerous vesicles indicating high metabolic activity and numerous filopodia and pseudopodia. This revealed that the chemico-physical characteristics of the starting surface are such as not to hamper colonization of the substrate.
• the SEM images revealed considerable cell proliferation, but above all the marked process of flattening of the cell body. There were in fact no longer visible cells with globose morphology or vesicles of cell activity.
• the SEM images showed a coexistence on the surface of cells with more flattened morphology alongside other more globose cells with intermediate morphology. After 24 hours, the cell density was visibly increased, but there were also present areas not yet colonized.
• All the laser-treated specimens (L5, LlO, L20) enabled adhesion and colonization by the SaOS-2 cells. This means that the laser treatment undergone by the surface of the titanium is not such as to induce onset of cytotoxic phenomena.
• the specimens L20 were the ones with the largest number of cells both after 6 and after 24 hours.
• the SEM images revealed that the bodies of the cells were strictly adherent both to the bottoms of the holes and to the portions of surface between the holes.
• the specimens L20 supported the highest cell proliferation.
• the cells grown on the specimens MAC always exhibit a flattened morphology of a fibroblastic type
• the cell body is frequently forced to assume shapes imposed by the structural irregularities, with characteristics more of an osteoblastic type.
• This datum suggests that the surfaces with holes obtained by means of laser treatment can present an effective improvement as compared to machined surfaces or to irregularly rough surfaces (such as sanded surfaces) , where cells coexist with a very different (flattened and polygonal) morphology.
• the experimental materials were constituted by cylinders made of commercially pure titanium having the same characteristics and the same surface finish as the ones described previously and designated by SAB, L5, LlO and L20.
• the cells used for the test were always of an osteoblastic type (SaOS-2) , as in the previous experiment.
• a suspension of 1.53 x 10 5 SaOS-2 cells in 2 ml of McCoy's culture medium with the addition of 15% of bovine foetal serum, L-glutamin, penicillin, streptomycin, and amphotericin B was introduced into sterile containers made of polystyrene with twelve compartments. Each well containing a cylinder hence received approximately 3 x 10 6 SaOS-2 cells. Simultaneously, after extraction from the sterile pack under the laminar-flow hood, all the cylinders available were also introduced. The containers were then put to incubate (5% CO 2 , 37°C, R. H. 98%), some for 3 days, others for 7 days, and others for 10 days.
• the alkaline-phosphatase enzyme catalyses conversion of p- nitrophenylphosphate into p-nitrophenol, which has an intense yellow colour and can thus be read spectrophotometrically at the corresponding wavelength.
• the value of the activity of the enzyme that is quantified by the absorbance was normalized by the total number of cells (specific activity) and then expressed as absorbance/cell.
• the first of these tests basically had the purpose of verifying whether the numerous extroversions present around the pores obtained with the laser (particularly evident on the surfaces with smaller pores) could release into the surrounding tissues micrometric particles of titanium, which are sometimes indicated in the literature as cause of inhibition of the mineralizing activity of the cells of bone tissue, of localized inflammatory processes, and also of diffusion of particles of titanium through the blood circulation to other organs.
• the tests were conducted by implanting in the femur of the rabbit, on three different subjects, a cylinder machined to a smooth surface with a diameter of 2.5 mm and a length of 6 mm, and a laser-treated cylinder of similar dimensions presenting a porous surface with the characteristics recalled above.
• the BIC is decidedly low, and osteoconductivity is not present on this implant surface.
• the laser-treated implants have a higher degree of bone contact (BIC 29.39%). There is noted a good level of osteoconductivity ( Figures 10 and 11) .
• the bone tends to encapsulate the implant, creating a perfect bone contact in the areas of adjacency, far more regular and continuous than in smooth titanium.
• the second in-vivo test was conducted once again on New Zealand rabbits, using, however, implants made of threaded titanium (diameter 2.5 mm; length 5 mm) specifically designed for use in rabbits.
• the purpose was to compare the degree of osteo-integration expressed as BIC% of laser-treated implants with pores of a diameter of between 5 and 40 ⁇ m and sanded implants.
• Figures 3 to 5 are photographs taken at the microscope, with increasing levels of enlargement, of an example of laser- treated implant according to the present invention.
• FIGS ⁇ and 7 illustrate two possible laser systems 10, 11 for the treatment of the implants.
• Figure 6 illustrates a simplified system 10 that is able to create a distribution of pores on the surface of the implant that is substantially homogeneous; even though the distribution is not perfect, it is obtained with a very high productivity.
• the system 10 comprises a laser generator 12, a scanning head 13, and a piece-holder assembly 14 for support, positioning and movement of the implants 1 during the process.
• the piece-holder assembly 14 basically comprises a horizontal table 15, which moves along two mutually perpendicular horizontal axes (X, Y) , and a spindle 16 for gripping the piece, which can turn about an axis ⁇ of its own coinciding in use with the axis of the implant being machined.
• the spindle is carried by a head 17, which is in turn carried by the table 15 and is orientable about a horizontal axis ⁇ perpendicular to the axis ⁇ so as to enable variation of the inclination of the axis ⁇ of the implant and compensate for the possible conicity of the implant to be machined.
• the laser generator 12 is of a DPSS (diode-pumped solid-state) type in Q-switch regime.
• the laser beam L generated is sent along an optical path P to the scanning head 13 set above the table.
• the scanning head 13 is designed to cause the laser beam to oscillate in a vertical plane containing the axis ⁇ of the spindle 16, with an alternating to-and-fro motion between two limit positions forming a pre-set angle between them so as to direct the beam on the implant substantially along a generatrix of the implant itself.
• the scanning head 13 is conveniently provided with an 18 f- theta lens that is able to focus correctly the beam L as its position varies during the movement of scanning.
• the scanning head 13 is conveniently mounted on a vertical guide 20 (axis Z) that enables regulation of the vertical position of the scanning head 13.
• a control unit 24 controls, in a co-ordinated way, the laser generator 12, the scanning head 13, and the piece-holder assembly 14.
• Machining is carried out by scanning the implant 1 with the laser beam L moved by the scanning head 13 and by simultaneous rotation of the implant about the axis a.
• the laser in Q-switch regime (nanosecond pulses) enables formation, during the scanning motion, of a succession of pores, by synchronizing appropriately the scanning speed and pulse frequency. Thanks to the high pulse frequency (e.g., 10 kHz) , it is possible to operate at very high scanning speeds (e.g., 300 mm/s) .
• each sweep of the motion of the scanning laser describes a generatrix of the implant, which remains stationary during machining; the implant is then rotated by a pitch at the end of each scanning sweep.
• the scanning laser in combination with the continuous rotation of the implant, describes a succession of helical lines on the latter.
• the incidence of the laser beam is in actual fact normal to the surface of the implant only in the bottom lands and top lands of the thread, but is necessarily inclined in the area of the flanks of the threads. This can produce both a dimensional alteration of the pores and a local variation in the distribution thereof. In this case, the dimensions and the pitch of the pores described and claimed are to be understood as average values.
• the system 11 of Figure 7 differs from that of Figure 6 in so far as it is able to control the angle of incidence of the laser beam on the implant.
• the laser beam L is directed on the implant by a focusing head 24, which is able to move along two axes Y and Z, by means of which it is possible to control the position of the beam L along the axis of the implant 1 and the distance of the focusing head with respect to the surface of the implant.
• the implant is mounted on a piece-holder head 26 having two degrees of freedom of rotation (about the axes ⁇ and ⁇ ) .
• the control unit 24 controls the four axes in a co-ordinated way during machining so as to keep the direction of incidence of the laser beam on the implant 1 instant by instant substantially perpendicular to the surface of the implant itself.
• DPSS lasers in Q-switch regime are conveniently used in the UV (third and fourth harmonic, wavelength of 355 and 266 nm, respectively) in TEMOO single-mode operation.
• the second harmonic (532 nm) in the green is conveniently used, once again in single-mode operation, and for pores with dimensions comprised between 30 and 50 ⁇ m the fundamental wavelength (1064 nm) in the IR is conveniently used, once again in single-mode operation.
• the same laser sources can be used, but functioning in multimode (higher power) .
• Laser machining can be carried out in a controlled atmosphere, for example using argon or neon as covering gas, or in vacuum conditions, in order to prevent any chemical alteration of the surface of the implant.
• a laser source of a DPSS type in Q-switch regime enables implants presenting an optimized surface topography, suitable for favouring proliferation and differentiation of cells of an osteoblastic type, to be obtained rapidly and economically.
• the method and the laser systems can be used for the treatment of implantable devices of another type, not necessarily for oral surgery.

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• 2006
  • 2006-02-08 IT IT000089A patent/ITTO20060089A1/it unknown
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