Apparatus and method for measuring optical characteristics of teeth

• US 7,785,103 B2
• Filed: 04/20/2008
• Issued: 08/31/2010
• Est. Priority Date: 06/30/1998
• Status: Expired due to Fees

• Current Assignee: RPX Corporation
• Original Assignee: JJL Technologies, L.L.C.
• Inventors: Jung, Wayne D., Loudermilk, Alan R., Jung, Russell W.
• Primary Examiner(s): Lewis, Ralph A
• Application Number:
  US12/148,530
• Publication Number:
  US 20080309924A1
• Time in Patent Office: 863 Days
• Field of Search: 433/29, 433/203.1, 356/419, 356/405, 356/406, 356/407, 356/402
• US Class Current: 433/29
• CPC Class Codes: A61B 5/0088 for oral or dental tissue
• CPC Class Codes: G01J 2003/1217 Indexed discrete filters or choppers
• CPC Class Codes: G01J 2003/1234 Continuously variable IF [CVIF]; Wedge type
• CPC Class Codes: G01J 2003/468 of objects containing fluorescent agent
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0208 using focussing or collimating elements, e.g. lenses or mirrors; performing aberration correction
• CPC Class Codes: G01J 3/0218 using optical fibers
• CPC Class Codes: G01J 3/0229 using masks, aperture plates, spatial light modulators or spatial filters, e.g. reflective filters
• CPC Class Codes: G01J 3/0264 Electrical interface; User interface
• CPC Class Codes: G01J 3/0272 Handheld
• CPC Class Codes: G01J 3/0278 Control or determination of height or angle information for sensors or receivers
• CPC Class Codes: G01J 3/0283 using a charging unit
• CPC Class Codes: G01J 3/0291 Housings; Spectrometer accessories; Spatial arrangement of elements, e.g. folded path arrangements
• CPC Class Codes: G01J 3/463 Colour matching
• CPC Class Codes: G01J 3/508 measuring the colour of teeth
• CPC Class Codes: G01J 3/51 using colour filters
• CPC Class Codes: G01J 3/513 having fixed filter-detector pairs
• CPC Class Codes: G01J 3/524 Calibration of colorimeters
• CPC Class Codes: G01N 21/251 Colorimeters; Construction thereof
• CPC Class Codes: G01N 21/474 Details of optical heads therefor, e.g. using optical fibres
• CPC Class Codes: G01N 21/57 : Measuring gloss

Abstract

A method for outputting a closest match of a plurality of electronically stored shade guide values of a dental shade guide system is disclosed. A protective tip including a hole for couples light from a probe to a measurement spot on a dental object. The probe is in proximity to a reference standard and a calibration/normalization measurement of the reference standard is taken. Light returned from the dental object is measured with an optical sensor. A first frequency proportional to an intensity of a first wavelength/spectral band of light is determined, a second frequency proportional to an intensity of a second wavelength/spectral band is determined, and a third frequency proportional to an intensity of a third wavelength/spectral band of light is determined. A closest match is selected of a plurality of electronically stored shade guide values of one or more dental shade guide systems.

Claims

1. A method for determining optical characteristics of a dental object with a handheld instrument having a probe comprising the steps of:

applying a protective tip to the probe, wherein the protective tip serves to prevent contact between the probe and the dental object, wherein the protective tip includes a hole for coupling light from the probe to a measurement spot on the dental object;

moving the probe having the protective tip applied thereto in proximity to a reference standard of known optical properties, and activating a calibration/normalization measurement of the reference standard via a switch/button user interface, wherein calibration/normalization data are stored based on electronic and optical properties of the handheld instrument having the protective tip applied thereto;

moving the probe having the protective tip in proximity to the dental object, and activating a measurement of the measurement spot of the dental object via the switch/button user interface, wherein light is provided to the measurement spot and returned from the measurement spot and coupled to an optical sensor;

measuring light returned from the measurement spot of a plurality of wavelengths/spectral bands with the optical sensor, wherein a first frequency proportional to an intensity of a first wavelength/spectral band of light returned from the measurement spot is determined, a second frequency proportional to an intensity of a second wavelength/spectral band of light returned from the measurement spot is determined, and a third frequency proportional to an intensity of a third wavelength/spectral band of light returned from the measurement spot is determined, wherein color measurement data are determined based on the light returned from the measurement spot based on at least the first, second and third frequencies;

based on the color measurement data, selecting a closest match of a plurality of electronically stored shade guide values of one or more dental shade guide systems; and

outputting the closest match of the plurality of electronically stored shade guide values of the one or more dental shade guide systems.

2. The method of claim 1, wherein for each of the first, second and third frequencies, a value is calculated based on a number of pulses divided by a counter value determined by a system clock.

3. The method of claim 2, wherein the counter value is determined based on a final counter value minus an initial counter value.

4. The method of claim 1, wherein the number of pulses is always greater than 2.

5. The method of claim 1, wherein light received by the optical sensor substantially comprises diffuse light returned from the measurement spot.

6. The method of claim 1, wherein a plurality of electronically stored shade guide values for a plurality of dental shade guide systems are stored in the handheld instrument.

7. The method of claim 1, wherein the closest match of the plurality of electronically stored shade guide values of the one or more dental shade guide system is output via a display on the handheld instrument.

8. The method of claim 7, wherein the handheld instrument is cordless and battery operated.

9. The method of claim 1, wherein the optical sensor comprises a light-to-frequency converter sensor.

10. The method of claim 1, wherein the optical sensor comprises a plurality of light-to-frequency converter sensors.

11. The method of claim 10, wherein at least certain of the plurality of light-to-frequency converter sensors receive light via a filter.

12. The method of claim 11, wherein a plurality of bandpass filters are provided, wherein a plurality of light-to-frequency converter sensors receive light via one of the plurality of bandpass filters.

13. The method of claim 12, wherein the plurality of bandpass filters comprise interference filters.

14. The method of claim 1, wherein the color measurement data are generated without a diffraction grating.

15. The method of claim 1, wherein the color measurement data are generated without a diffraction grating and without an analog-to-digital converter.

16. The method of claim 1, wherein the tip is cone-shaped.

17. The method of claim 1, wherein a plurality of the first, second and third frequencies are measured with a plurality of sensors in a parallel manner.

18. The method of claim 1, wherein audio feedback is provided to an operator of the instrument, wherein the audio feedback includes a beep or tone indicating completion of a measurement.

19. The method of claim 1, wherein light is provided from the probe to the measurement spot via a broadband light source.

20. The method of claim 1, wherein light is provided from the probe to the measurement spot via a plurality of monochromatic light sources.

21. A method for determining optical characteristics of a dental object with a handheld instrument having a probe comprising the steps of:

applying a protective tip to the probe, wherein the protective tip serves to prevent contact between the probe and the dental object, wherein the protective tip includes a hole for coupling light from the probe to a measurement spot on the dental object;

moving the probe having the protective tip applied thereto in proximity to a reference standard of known optical properties, and activating a calibration/normalization measurement of the reference standard, wherein calibration/normalization data are stored based on electronic and optical properties of the handheld instrument having the protective tip applied thereto;

moving the probe having the protective tip in proximity to the dental object, and activating a measurement of the measurement spot of the dental object, wherein light is provided to the measurement spot via one or more light sources and returned from the measurement spot and coupled to one or more optical sensors for determination of color measurement data;

measuring light generated via the one or more light sources in a plurality of wavelengths/spectral bands with one or more of the optical sensors, wherein a first frequency proportional to an intensity of a first wavelength/spectral band of light generated via the one or more light sources is determined, a second frequency proportional to an intensity of a second wavelength/spectral band of light generated via the one or more light sources is determined, and a third frequency proportional to an intensity of a third wavelength/spectral band of light generated via the one or more light sources is determined, wherein the color measurement data are determined based in part on at least the first, second and third frequencies;

based on the color measurement data, selecting a closest match of a plurality of electronically stored shade guide values of one or more dental shade guide systems; and

outputting the closest match of the plurality of electronically stored shade guide values of the one or more dental shade guide systems.

22. The method of claim 21, wherein a plurality of electronically stored shade guide values for a plurality of dental shade guide systems are stored in the handheld instrument.

23. The method of claim 21, wherein the closest match of the plurality of electronically stored shade guide values of the one or more dental shade guide system is output via a display on the handheld instrument.

24. The method of claim 21, wherein the measurement sensor comprises a light-to-frequency converter sensor.

25. The method of claim 21, wherein the measurement sensor comprises a plurality of light-to-frequency converter sensors.

26. The method of claim 25, wherein at least certain of the plurality of light-to-frequency converter sensors receive light via a filter.

27. The method of claim 21, wherein data based on the light generated by the one or more light sources are generated without a diffraction grating and without an analog-to-digital converter.

28. The method of claim 21, wherein light is provided from the probe to the measurement spot via a broadband light source.

29. The method of claim 21, wherein light is provided from the probe to the measurement spot via a plurality of monochromatic light sources.