Dental procedures and apparatus using ultraviolet radiation

• US 5,435,724 A
• Filed: 07/06/1994
• Issued: 07/25/1995
• Est. Priority Date: 03/04/1993
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Wynne, James J., Jacobs, Jason M., Kaufman, Hershall W., Goodman, Barry D.
• Primary Examiner(s): Pellegrino, Stephen C.
• Assistant Examiner(s): PEFFLEY, MICHAEL F
• Application Number:
  US08/271,385
• Time in Patent Office: 384 Days
• Field of Search: 606/2, 606/3, 606/10-17, 433/215, 433/216, 607/89
• US Class Current: 433/215
• CPC Class Codes: A61B 17/24 for use in the oral cavity, larynx, bronchial passages or nose for medical inspection of cavities or tubes in the body A61B1/00; Tongue scrapers
• CPC Class Codes: A61B 18/20 using laser
• CPC Class Codes: A61B 18/201 with beam delivery through a hollow tube, e.g. forming an articulated arm through a flexible conduit A61B18/22; Hand-pieces therefor
• CPC Class Codes: A61B 2017/00022 Sensing or detecting at the treatment site
• CPC Class Codes: A61B 2017/00128 related to intensity or progress of surgical action
• CPC Class Codes: A61B 2018/00636 Sensing and controlling the application of energy
• CPC Class Codes: A61B 2218/008 for smoke evacuation
• CPC Class Codes: A61C 1/0046 Dental lasers surgical lasers A61B18/20; working by laser beam in general B23K26/00; lasers per se H01S3/00
• CPC Class Codes: B23K 26/03 Observing, e.g. monitoring, the workpiece
• CPC Class Codes: B23K 26/032 using optical means

Abstract

An improved dental procedure and apparatus where ultraviolet radiation pulses are used to etch selectively both hard tissue and soft tissue in dental procedures. There exists distinct ablation thresholds for hard and soft tissue which are dependent on the material being ablated for a given wavelength of the ultraviolet radiation. Sufficient differences in ablation threshold exist for enamel, dentin, and carious material, thereby allowing dentists to perform both hard tissue and soft tissue procedures without excess damage to healthy enamel, dentin or other pulp structures.

Claims

1. A method for performing dentistry, including the steps of:

irradiating a region of a tooth with ultraviolet radiation of sufficient energy fluence F₁ to ablate enamel therefrom by a mechanism which causes minimal thermal diffusion to areas surrounding said region,

continuing said irradiating until the desired amount of enamel is removed from said region,

changing the energy fluence of said ultraviolet radiation to an amount F₂ sufficient to ablate carious material in said tooth but less than that which is necessary to ablate enamel,

irradiating carious material in said tooth with ultraviolet radiation of energy fluence F₂ for a time period sufficient to ablate said carious material, thereby restoring a more healthy state to said tooth, and

irradiating dentin in said tooth with ultraviolet radiation having an energy fluence greater than the energy fluence threshold F₃ required to ablate dentin therefrom, the fluence F₃ being less than F₂.

2. The method of claim 1, where said energy fluence F₁ is greater than about 5.8 J/cm² when said ultraviolet radiation has a wavelength of about 308 nm.

3. The method of claim 2, where said energy fluence F₂ is less than about 5.8 J/cm² and greater than about 1.3 J/cm² when said ultraviolet radiation has a wavelength of about 308 nm.

4. The method of claim 1, wherein said ultraviolet radiation is in the range of about 100-400 nm.

5. The method of claim 1, where said ultraviolet radiation is in the range of about 300-400 nm.

6. The method of claim 1, where said ultraviolet radiation is in the wavelength range of about 185-220 nm.

7. The method of claim 1, including the step of irradiating both carious material and dentin with an energy fluence sufficient to ablate both carious material and dentin, and removing aid carious material at a rate greater than the rate of removal of dentin.

8. The method of claim 1, where said energy fluence is lowered to a level less than the level necessary to ablate dentin, carious material, and enamel, said ultraviolet radiation being used to cleanse the mouth of germs.

9. A method for laser dentistry, including the steps of:

irradiating a region of a tooth with ultraviolet laser pulses having energy fluence greater than the threshold energy fluence F₁ needed to ablate enamel,

continuing said irradiating to remove a desired amount of enamel from said tooth,

irradiating said tooth with ultraviolet radiation pulses of a second energy fluence less than level F₁, but greater than the threshold level F₂ necessary to ablate carious material, to ablate therefrom carious material without ablating enamel,

continuing said irradiating at said second energy fluence level unit the desired amount of carious material is ablated therefrom, and

irradiating said tooth at a third energy fluence level which is greater than the threshold level F₃ required to ablate dentin but less than the threshold level required to ablate carious material or enamel, in order to remove dentin from said tooth, said irradiating continuing until the desired amount of dentin is removed.

10. The method of claim 9, where said laser is an excimer laser.

11. The method of claim 10, where said ultraviolet radiation is in the wavelength range of 100-400 nm.

12. The method of claim 10, where said ultraviolet radiation is in the wavelength range of about 300-400 nm.

13. The method of claim 10, where said ultraviolet radiation is in the wavelength range of about 185-220.

14. A method of dentistry including the steps of:

irradiating a region of a tooth with ultraviolet laser radiation having an energy fluence greater than the threshold energy fluence F₃ required to ablate healthy dentin therefrom but less than the threshold energy F₂ required to ablate carious material therefrom, and

continuing said irradiation until the desired amount of healthy dentin is removed from said tooth.

15. The method of claim 14, where said energy fluence F₃ is greater than about 1.04 J/cm² and less than about 1.36 J/cm² when said ultraviolet radiation has a wavelength of about 308 nm.

16. The method of claim 14, including the further step of irradiating said tooth with ultraviolet radiation pulses having an energy fluence at least equal to an energy fluence F₂ at which carious material is ablated from said tooth without ablating any enamel which is irradiated by said laser radiation.

17. The method of claim 16, where said energy fluence level is greater than about 1.36 J/cm² and less than about 5.9 J/cm² when the wavelength of said ultraviolet radiation is about 308 nm.

18. The method of claim 16, including the further step of irradiating said tooth with ultraviolet laser radiation having an energy fluence greater than the threshold energy fluence F₁ at which enamel is ablated from said tooth.

19. The method of claim 14, including the further step of irradiating said tooth with ultraviolet laser radiation having an energy fluence level greater than the fluence F₁ at which enamel is ablated from said tooth.

20. The method of claim 19, where the fluence F₁ is approximately 5.9 J/cm² when said ultraviolet radiation has a wavelength of about 308 nm.

21. A method of dentistry including the step of irradiating a tooth with ultraviolet radiation pulses to deposit therein a sufficient energy per unit volume to ablate dentin therefrom without ablating carious material or enamel, the pulse repetition rate and the pulse widths of said ultraviolet radiation pulses being less than that which would cause a significant temperature rise in regions surrounding the irradiated region of said tooth.

22. The method of claim 21, including the further step of irradiating carious material in said tooth with ultraviolet radiation pulses to deposit sufficient energy per unit volume in said carious material to ablate carious material by a mechanism which substantially limits carious material removal to the irradiated region of said tooth, where said energy per unit volume being deposited is less than the amount necessary to ablate enamel from said tooth.

23. The method of claim 21, including the further step of irradiating enamel in said tooth with ultraviolet radiation pulses to deposit a sufficient energy per unit volume in said enamel to ablate it by a mechanism which substantially limits enamel removal to the irradiated region of said tooth.

24. A method of dentistry including the steps of:

irradiating a tooth with ultraviolet radiation pulses of sufficient energy fluence to exceed the threshold required to ablate carious material from said tooth,

irradiating said tooth with ultraviolet radiation pulses of sufficient energy fluence to exceed the threshold required to ablate dentin from said tooth, and

irradiating said tooth with ultraviolet radiation pulses having an energy fluence greater than the threshold energy fluence required to ablate enamel from said tooth, the threshold energy fluences per pulse necessary to ablate dentin, carious material and enamel from said tooth being different from one another.

25. The method of claim 24, where the threshold energy fluence per pulse necessary to ablate dentin from said tooth is less than the threshold energy fluence per pulse necessary to ablate carious material from said tooth.

26. The method of claim 24, where the threshold energy fluence per pulse necessary to ablate enamel from said tooth is approximately five times as large as the threshold energy fluence per pulse necessary to ablate dentin and carious material from said tooth.

27. The method of claim 24, where the threshold energy fluence per pulse necessary to ablate dentin from said tooth is about 1 J/cm².

28. The method of claim 24, where the threshold energy per unit volume deposited in said tooth and necessary for ablating carious material therefrom is less than the deposited energy per unit volume necessary to ablate dentin at a given ultraviolet wavelength radiation.

29. The method of claim 28, including the step of delivering ultraviolet radiation pulses to said tooth to deposit in said tooth an energy per unit volume greater than the threshold energy per unit volume required for ablation of carious material therefrom but less than the threshold energy per unit volume required to be deposited for the ablation of dentin therefrom.

30. The method of claim 28, including the step of depositing in said tooth ultraviolet energy having an energy per unit volume greater than that required to be deposited for the ablation of dentin from said tooth but less than the threshold energy per unit volume required to cause ablation of enamel therefrom.

31. The method of claim 28, including the step of irradiating said tooth with ultraviolet radiation pulses to deposit in said tooth an energy per unit volume in excess of the threshold energy per unit volume required to ablate enamel therefrom.