Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C1/00—Dental machines for boring or cutting ; General features of dental machines or apparatus, e.g. hand-piece design
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C1/00—Dental machines for boring or cutting ; General features of dental machines or apparatus, e.g. hand-piece design
  • A61C1/0046—Dental lasers
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B34/00—Computer-aided surgery; Manipulators or robots specially adapted for use in surgery
  • A61B34/70—Manipulators specially adapted for use in surgery
  • A61B34/72—Micromanipulators
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
  • A61B2017/00743—Type of operation; Specification of treatment sites
  • A61B2017/00787—Surgery of the ear
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
  • A61B18/18—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves
  • A61B18/20—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using laser
  • A61B2018/2015—Miscellaneous features
  • A61B2018/2025—Miscellaneous features with a pilot laser
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
  • A61B18/18—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves
  • A61B18/20—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using laser
  • A61B2018/2035—Beam shaping or redirecting; Optical components therefor
  • A61B2018/20351—Scanning mechanisms
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
  • A61B18/18—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves
  • A61B18/20—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using laser
  • A61B2018/2035—Beam shaping or redirecting; Optical components therefor
  • A61B2018/20351—Scanning mechanisms
  • A61B2018/20355—Special scanning path or conditions, e.g. spiral, raster or providing spot overlap
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
  • A61B18/18—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves
  • A61B18/20—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using laser
  • A61B2018/206—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using laser the laser light passing along a liquid-filled conduit

Definitions

• the present invention relates to apparatus and method for laser vaporization of hard tissue and deposits on hard tissue, such as teeth and bones, with a laser scanner in general and more particularly with a laser scanner and a pulsed laser beam.
• Teeth cleaning conventionally involves mechanical instruments that vibrate or pick at deposits to remove the deposits, such as plaque between teeth and gums. Some discomfort is felt during this mechanical cleaning technique.
• mechanical drills are used to make holes in teeth and even the sound of their motors may cause concern or anxiety to the patient. A local anaesthetic is usually needed because the drilling procedure is painful. Mechanical vibrations, mechanical contact of the drill with the tooth and irritative noise are the main disadvantages of mechanical drills.
• E ⁇ YAG and ER ⁇ SSG Erbium based lasers
• C0 2 laser C0 2 laser
• One drawback of prior art use of lasers in hard tissue applications is that in order to provide a laser beam having enough energy density to ablate the hard tissue or the deposits on the hard tissue one has to provide a laser beam having a spot size on the order of tens of microns or few hundred microns which is an order of magnitude or more smaller than the size of the target area to be ablated.
• a laser beam having a spot size on the order of tens of microns or few hundred microns which is an order of magnitude or more smaller than the size of the target area to be ablated.
• the spot size of the ablating laser is one to two orders of magnitude smaller.
• the laser has to be applied in relatively short pulses and delivered in a low repetition rate in order to avoid undesirable thermal damage, such as cracking of enamel and dentin or thermal damage to the pulp.
• a focused beam on the order of 100 microns, the energy density required for hard tissue vaporization is provided.
• a scanner to scan the focussed beam over a target area, vaporization of a target area of any size and shape, typically an order of magnitude or more than the spot size of the laser beam is attained.
• a SilkTouchTM flashscanner manufactured and sold by Laser Industries Ltd. of Tel Aviv, Israel, previously used with various types of lasers to radiate soft tissue, is used with lasers operative in accordance with the present invention to form a sequence of micro-holes which when taken together provide a large, clean, char-free vaporized target area of any desired size and shape in the hard tissue while substantially avoiding thermal damage to adjacent tissues.
• Flashscanners suitable for making any desired pattern are exemplified in the following disclosures:
• a method for vaporizing any one of hard tissue and deposits on hard tissue includes the steps of substantially continuously scanning a target area, the target area being any of hard tissue and deposits on hard tissue and directing a pulsed laser beam during the scanning so as to vaporize portions of the target area, thereby forming a vaporized target area of a desired size, preferably between 0.5 and 6 millimeters and any desired shape.
• the shape of the target area are circular, elliptic, squared, rectangular or in the shape of a slit.
• the method may include the step of focussing the laser beam to provide an energy density sufficient to vaporize each the portion of the target area.
• the method may include the step of selecting a scanning speed for the scanning and providing a maximal repetition rate for the pulses of the pulsed laser beam in accordance to the scanning speed.
• the method may include the step of repeating the steps of scanning and directing to complete a plurality of passes of the target area until a desired overall penetration is attained.
• the method also includes the step of cooling the vicinity the target area, thereby avoiding thermal damage to adjacent tissue or char.
• the step of directing includes the step of directing the laser beam in a rate that results in the laser beam dwelling at each of the regions for a duration that is less than that which would cause thermal damage to adjacent tissue or char.
• an apparatus for vaporizing any one of hard tissue and deposits on hard tissue includes a laser, preferably a C0 2 laser, for generating a pulsed laser beam and a scanner for substantially continuously scanning a target area, the target area being any of hard tissue and deposits on hard tissue and for directing a pulsed laser beam during the scanning so as to vaporize portions of the target area, thereby forming a vaporized target area of a desired size and shape.
• a laser preferably a C0 2 laser
• the apparatus may generate a focussed laser beam which provides an energy density sufficient to vaporize each the portion of the target area.
• the apparatus also includes a control unit for selecting a scanning speed for the scanning and for providing a maximal repetition rate for the pulses of the pulsed laser beam in accordance to the scanning speed.
• the C0 2 laser operates with a wavelength of 9.3 to 11.2 microns, preferably in the 9.6 micron band, the pulse frequency is 1 - 1000 Hz, preferably below 200 Hz, each pulse has a pulse duration of less then 100 microseconds and the spot size of the beam is between 100 - 300 microns.
• Fig. 1A is a schematic illustration of an apparatus for performing a stapedectomy, constructed and operative in accordance with a preferred embodiment of the present invention
• Fig. 1B is a schematic illustration of an apparatus for teeth vaporization and for vaporizing deposits on teeth, constructed and operative in accordance with a preferred embodiment of the present invention
• Fig. 2A is a schematic representation of a spiral pattern formed from a sequence of micro-holes being formed by employing the apparatus of Fig. 1A or Fig. 1B in accordance with a preferred method of the present invention
• Fig. 2B is a schematic representation of a larger hole formed after completion of the spiral pattern of Fig. 2A;
• Fig. 3A is a schematic representation of a rectangular pattern formed from a sequence of micro-holes being formed by employing the apparatus of Fig. 1A or Fig. 1 B in accordance with another preferred embodiment of the present invention
• Fig. 3B is a schematic representation of a larger rectangular hole formed after completion of the rectangular pattern of Fig. 2A;
• Fig. 4 is a schematic representation of a tooth being drilled in accordance with a preferred method of the present invention and further illustrates the vaporization of plaque in accordance with another preferred embodiment of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENT
• Fig. 1A illustrates an apparatus, generally referenced 1 , constructed and operative according to one preferred embodiment of the present invention.
• Apparatus 1 which is particularly suitable for performing stapedectomy comprises a micromanipulator 10, a flashscanner 12, an articulated arm 14, a surgical microscope 16 and a laser 18 generating a laser beam 20 which is preferably but not necessarily a pulsed laser beam.
• the flashscanner 12 has movable vibrating or rotating mirrors 22 which operate to provide the scanned pattem.
• the flashscanner 12 is the one disclosed in the '386 application and '502 patent in conjunction with a laser having an articulated arm.
• the present invention is not limited to the scanners of the '386 application and the '502. Rather, according to the present invention any suitable scanner, such as the one described in U.S. Patent 5,546,214 to Black et al. may be used.
• the micromanipulator 10 includes a dichroic mirror 26 whose relative position therewithin is changed in response to movement of an adjustment handle 28.
• the surgical microscope 16 is arranged to permit viewing through the dichroic mirror 26 from the surgical microscope 16.
• the laser 18 is a C0 2 laser, which is pulsed during scanning.
• the CO z laser is a continuous working C0 2 laser.
• laser 18 provides laser beams 20 in a wavelength between 9.3 and 11.2 microns, preferably in the 10.6 micron band and most preferably in the 9.6 micron band.
• the 9.6 micron band is preferred due to the higher absorption of this band by Hydroxyapatite which is a main component of human hard tissue.
• Fig. 1 B illustrates an alternative apparatus to the apparatus of Fig. 1 A having a configuration which is particular suitable for applications related to teeth, non limiting examples being vaporizing enamel and dentin so as to form a hole of any desired size and shape in the teeth 52 or for vaporizing plaque and caries from the surface of teeth 52 as described in detail hereinbelow.
• Fig. 1 B illustrates apparatus 1 having similar elements and referred to by similar reference numerals without the surgical microscope 16 since for dental applications surgical microscope 16 is often not required.
• the apparatus of Fig. 1B forms a hand piece held by the dentist.
• the laser beam 20 is initially a visible pilot laser beam which helps the physician 30 in aiming the treatment laser beam to a striking location.
• the surgical vaporization within the pattern 38 on the hard tissue may commence, such as in the target area 36 of the stapes bone 32 (Fig. 1A) or the teeth 52 (Fig. 1B).
• Figs. 2A and 2B illustrate the formation of a hole 40, whose size is about 600 microns in diameter to accommodate implantation of a prosthesis (not shown). This hole 40 is formed through repeating the scan of the surgical vaporization pattern 38 as many times as needed until a desired penetration is attained.
• rounded holes such as hole 40 (Fig. 2B) are typically 1 - 5 millimeters in diameter and holes of other shapes, such as the hole 41 of Fig. 3B which may also be formed by a spiral pattern (Fig. 3A) are generally of similar sizes.
• the flashscanner 12 is first set to sweep the target area 34 to generate the surgical vaporization pattern 38 in the form of a spiral.
• a focused laser beam 20 of a single pulse then sweeps the pattem 38 in a spiral from spot to spot to form micro-holes 42 in sequence on the target area 36.
• the single large hole 40 develops, made from the combination of all the micro- holes 42, with minimal char and minimal tissue damage outside the target area 36. By sweeping the pattern again repeatedly with pulses, the large hole 40 increases its depth.
• Typical operating modes of the laser with flashscanner include superficial vaporization of large surfaces, e.g., plaque, carries and laser drilling of a deeper hole in hard tissue such as teeth and bones.
• the laser is preferably a C0 2 laser that is pulsed during scanning.
• the use of the scanner as described above is advantageous in many respect for hard tissue vaporization.
• the use of the scanner in addition to the use of a relatively low energy laser while vaporizing larger target areas allows heat dissipation between consecutive firing on the same location of the target area so as to avoid cracks in the teeth and thermal damage to adjacent tissue.
• the use of the scanner enables the use of a higher pulse frequency than would be possible without the scanner so as to more rapidly drill in the hard tissue substantially without causing thermal damage to adjacent tissue.
• the use of the scanner allows for the use of a laser having relatively low energy per pulse and high repetition rate so as to substantially avoid thermal damage to adjacent tissue. Noniimiting operational parameters are described hereinbelow for exemplary applications.
• a repetitively pulsed C0 2 laser 18 is used in conjunction with the flashscanner 12 to provide a sequence of micro-holes 42 which combine to form a large, clean, char- free rounded hole 40 (Fig. 2B) or a rectangular hole 41 (Fig. 3B).
• the apparatus of Figs. 1A and 1 B are operative to vaporize a target area of any desired size and shape.
• the sequence of micro-holes 42 is spiral and the resulting hole in the hard tissue 40 is rounded.
• the sequence is also spiral and the resulting hole 41 in the hard tissue is rectangular.
• Other patterns such as a lissajous pattem may also be followed to provide holes of similar or different shapes.
• the repetition rate of the pulsed laser and the scanning rate are synchronized to achieve full surface coverage and depth homogeneity.
• the advantage in combining a pulsed mode and a flashscanner stems form the ability of a focused pulsed beam to achieve extremely clean vaporization.
• Typical parameters for use in stapedectomy operations to drill a 0.6 millimeter diameter hole in each scan period with 1 millimeter depth include a focal spot size of 100 microns to 300 microns, a power level of 10 to 30 watts, a laser energy per pulse of 20 to 50 millijoules, a repetition rate of approximately 500 Hertz, a pulse duration of less than 1 millisecond and a scanning period time of 0.2 seconds to 1 second. Increasing the scan duration time increases the hole depth.
• the focal length of the micromanipulator may be between 250 to 310 millimeters.
• each beam scan of a pattern may generate a 50 micron crater depth with a 500 - 700 micron diameter spot size after a 0.2 second duration per scan pass. It is preferable to wait between scan passes to look at the result before continuing the cycle.
• the laser may be fired for up to one second continuously or stopped after each of five scan passes (for a total of one second of exposure to laser radiation).
• the flashscanner may be used to make successive smaller holes which, when taken together, result in the same size hole as is made by the one large pulse. The difference lies in that with the flashscanner, the hole may be of any desired size and shape and the rate in which the process is completed is faster.
• Fig. 4 depicts further applications of the invention in the treatment of caries 50 in a tooth 52, and the vaporization of plaque 54 between the tooth 52 and gum
• the present invention is directed to any dental application in which vaporization of teeth is required, such as cavity preparation, etching for preparing teeth surfaces for composite material bonding and any other dental procedure where vaporization of dentin or enamel is required in restorative dentistry.
• the power level may be about 1 to 21 watts, preferably 3 - 8 watts;
• the scanning period may be about 0.1 to 0.3 seconds, preferably 0.2 seconds;
• the spot size diameter preferably may be about 0.2 millimeters.
• the scanning diameter is preferably 0.5 mm to 6 mm in any desired shape, such as circular, elliptical, rectangular, squared or in the form of a slit.
• the focal length may be about 100 millimeters and the laser may be operated in the superpulse mode at energy levels of 20 - 80 millijoules.
• the pulse frequency for drilling in teeth is preferably between 1 - 1000 Hz and the pulse duration is preferably below 200 microseconds.
• the scanner can be either synchronized with the laser beam triggering control or can be completely independent of the laser.
• the scanning frequency and the pulse repetition frequency should be slightly different in order to avoid a situation where the laser keeps drilling at the same point.
• the smallest typical scan diameter is about 1 millimeter.
• Operational parameters for vaporizing a hole of 2 millimeters in diameter, 3 millimeters deep may be as follows: the pulse frequency is 120 - 180 Hz, the pulse duration is about 60 microseconds, the spot size of the focussed C0 2 beam is 200 microns, the duration of each scan is 0.2 seconds and 5 microns of hard tissue are being vaporized in each scan. This results in a drilling rate of 25 microns per second and in a total scanning time of 2 minutes to attain the 3 millimeters depth.
• the diameter of the scanning hole beam or spot size may be from about 0.2 millimeters to 1 millimeter, but its size is dependent upon the size of the decayed area.
• the remaining parameters are the same as for plaque vaporization but the number of scanning cycles is significantly lower.
• the hole formed is filled with conventional filling material to prevent the further accumulation of matter that leads to decay.
• the C0 2 laser is continuous working for superficial vaporization of large surfaces
• the operative parameters include about a 40 Watt power level, about a one millisecond flashscanner dwelling time on single spots with about a 100 - 300 micron focal spot size and about a 0.1 - 0.3 second scanning duration for superficial vaporization of a single, approximately 50 micron, layer of plaque that has about a 2-6 millimeter diameter.
• This permits the cleaning of deposits on teeth or vaporization of bones, among other applications.
• the C0 2 laser may be pulsed and used for the same purpose (e.g., set at superpulse, SharpulseTM, SurgipulseTM, UltrapulseTM as exemplary settings).
• the operative parameters include a power level ranging form 30 watts to 150 watts, about a 0.3 millisecond dwelling time on tissue with about a 100 - 300 micron focal spot size and about a 0.2 to 1 second scan pulse duration.
• Each scan may vaporize a hole with a 0.5 millimeter to 2 millimeter diameter but multiple scan cycles are necessary to drill holes to a depth of 1 to 3 millimeters.
• the physician or dentist must first identify where the laser radiation is to strike. This is done through visual inspection, preferably with the aid of a visible pilot laser beam. Thereafter, the C0 2 laser is fired to complete one full scan and is repeated until the desired overall depth is attained. After each scan, the results can be observed.
• the vicinity of the target area is cooled by suitable cooling means, such as by a spray of water, so as to ensure that the vaporization of the hard tissue performed by the laser will be completed substantially without thermal damage to adjacent tissues.
• suitable cooling means such as by a spray of water

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• 1996
  • 1996-09-04 WO PCT/IL1996/000099 patent/WO1997010768A2/en not_active Application Discontinuation
  • 1996-09-04 AU AU68883/96A patent/AU6888396A/en not_active Abandoned
  • 1996-09-04 EP EP96929502A patent/EP0854692A2/de not_active Withdrawn
  • 1996-09-04 BR BR9610936-0A patent/BR9610936A/pt not_active Application Discontinuation
  • 1996-09-04 JP JP51254197A patent/JP2002517159A/ja active Pending
  • 1996-09-04 KR KR1019980705545A patent/KR19990044706A/ko not_active Application Discontinuation

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