Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
2000-07-28
2003-06-24
Lateef, Marvin M. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S477000, C433S029000, C433S037000, C433S068000
Reexamination Certificate
active
06584341
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a metrologic methodology and instrumentation, in particular to laser-frequency-domain infrared photothermal radiometry (henceforth referred to as FD-PTR or simply PTR) and frequency-domain luminescence (henceforth referred to FD-LM, or simply LM), for detection of dental defects and caries intraorally.
BACKGROUND OF THE INVENTION
In recent years rapidly increasing research activities have been reported centered on laser induced dc luminescence generated by a continuously (uninterrupted) illuminating optical source as a probing technique for the detection and quantification of physical and chemical processes associated with carious dental enamel. In general, dc luminescence suffers from low signal levels and thus in most cases dyes are used to enhance sensitivity [V. D. Rijke and J. J ten Bosch, “Optical quantification of caries like lesions in vitro by use of fluorescent dye”, J. Dent. Res. 69, 1184-1187 (1990)]. Under laboratory conditions, the results appear satisfactory, yet the use of dyes makes the method difficult for clinical applications. Another promising approach is laser-scanned dc fluorescence (or dc luminescence). This technique can detect early carious lesions [J. Baron, K. Zakariasen and B. Patton, “Detecting CO
2
laser effects by 3D image scanned laser fluorescence”, J. Dent. Res. 72, special issue #1060, 236 (1993);] by producing surface images which are subsequently enhanced via standard image processing techniques [C. D. Gonzalez, K. Zakariasen, D. N. Dederich and R. J. Pruhs, “Potential preventive and therapeutic hard tissue applications of CO
2
and Nd:YAG and Argon lasers in dentistry: A review”, J. Dent. Child May-June, 196-207 (1996)]. Nevertheless, the relatively low SNR limits the contrast and the diagnostic ability of dc laser fluorescence.
There have been three patents issued directed to methods involving dc laser luminescence. (R. R. Alfano, U.S. Pat. No. 4,290,433, Sep. 22, 1981; R. Hibst et. al., U.S. Pat. No. 5,306,144, Apr. 26, 1994; R. Hibst et. al. U.S. Pat. No. 6,024,562, Feb. 15, 2000). The last of these patents makes reference to using periodically modulated (chopped) radiation as a means to eliminating (“quasi-filtering out”) the background environmental light interference from the illuminated tooth. A suitable chopping frequency is advised, so as not to coincide with the power-line oscillation frequency. It should be noted that the idea of background light-filtering through modulation described in the patent by R. Hibst et al., neither in spirit, nor in practice does it lead those skilled in the art to our method of providing frequency-scanned amplitude and phase signals of modulated (ac) luminescence as a dental diagnostic means in their own right, where the frequency behavior of the LM signal is used to deduce dynamic optical and photothermal properties of the irradiated region, including scanning imaging.
The technique disclosed in U.S. Pat. No. 5,306,144 issued to R. Hibst et. al., and U.S. Pat. No. 6,024,562 issued to R. Hibst et. al. relies upon long lived fluorescence present in carious regions of the tooth that only emits in the red spectral region. This decay time and spectral characteristics are typical of metal free porphyrin monomers (Konig, K., Schneckenburger, H., Hibst, R., “Time-gated in vivo autofluorescence imaging of dental caries”, Cell Mol. Biol., 1999, March, Volume 45, #2, pages 233-239). The spectral characteristics were found to be typical of protoporphyrin IX, which may be present due to bacterial biosynthesis occurring within carious tissue (Konig, K., Flemming, G., Hibst, K., “Laser—induced autofluorescence spectroscopy of dental caries”, Cell Mol. Biol., 1998, December, Volume 44, #8, pages 1293-1300). There is also speculation that pigments present in specific foods or drink may be responsible (Longbottom, C., “Caries detection—Current status and future prospects using lasers”, in Lasers in Dentistry VI, Featherstone, J. D. B., Rechmann, P., Fried, D., Proceedings of SPIE, 2000, Volume 3910, pages 212-218). This is a much different approach to finding carious regions than the invention disclosed in the present patent.
A variety of methods have been developed for using lasers to treat carious tooth structures. Yessik et al. (U.S. Pat. No. 5,621,745 Apr. 15, 1997) describes one method of using a modulated pulsed laser to remove carious tooth material. Kowalyk (U.S. Pat. No. 5,281,141, Jan. 25, 1994) describes a method for using a Nd:YAG laser to treat and remove carious tooth material.
A number of laser systems have been proposed for curing or setting composite resins that are used to directly restore teeth. These resins are placed into cavity preparations that encompass the defects in the tooth or the carious regions of the tooth. Kowalyk (U.S. Pat. No. 5,281,141, January 1994), Kowalyk et al. (U.S. Pat. No. 5,456,603, October 1995), Levy (U.S. Pat. No. 5,885,082 March 1999) and Cipolla (U.S. Pat. No. 5,616,141 April 1997) disclose several techniques for curing or acting as a catalyst for the curing of light cured or dual cured dental composites. Issues such as polymerization shrinkage of the composite resin from the cavity or tooth walls are still being examined (Cobb, D S., et al. “
Physical properties of composite cured with conventional or argon laser
”, Am. J., 1996, October, Volume 9, No. 5, pages 199-202), (Tarle et al. “
The effect of photopolymerization method on the quality of resin samples
”, J. Oral Rehabil., 1998, June, Volume 25, No. 6, pages 436-442). Laser systems may be utilized in the photopolymerization of composites, but heat generation and marginal integrity of the restoration still need to be examined.
Frequency-Domain Photothermal Radiometry (FD-PTR) is a growing technology for the nondestructive evaluation (NDE) of sub-surface features in opaque materials [M. Munidasa, T. C., A. Mandelis, S. K. Brown, and L. Mannik, “Non-destructive depth profiling of laser processed Zr-2.5Nb alloy by infrared photothermal radiometry”, J. Mat. Sci. Eng. A 159, 111-118 (1992), G. Walther, “Photothermal nondestructive evaluation of materials with thermal waves” in
Progress in photothermal and photoacoustic science and technology
, A. Mandelis, ed., Vol. 1, pp. 205-298 Elsevier, N.Y. (1992)]. It has also shown promise in the study of excited-state dynamics in active optically transparent solid-state (laser) materials [A. Mandelis, M. Munidasa, and A. Othonos, “Single-ended infrared photothermal radiometric measurements of quantum efficiency and metastable lifetime in solid-state laser materials: the case of ruby (Cr
3+
:Al
2
O
3
)”, IEEE J. Quant. Electron. 29, 1498-1504 (1993)].
The FD-PTR technique is based on the modulated thermal infrared (blackbody or Planck-radiation) response of a medium, resulting from radiation absorption, non-radiative energy conversion and excited-to-ground-state relaxation, followed by temperature rise and subsequent emission of infrared photons. The generated signals carry sub-surface information in the form of a temperature depth integral. As a result, PTR has the ability to penetrate and yield depth-profilometric information about an opaque medium well below the range of optical imaging. Owing to this ability, pulsed-laser PTR has been extensively used with turbid media such as tissue [A. J. Welch and M. J. C. van Gemert eds., in
Optical
-
thermal response of laser
-
irradiated tissue
, Plenum, N.Y (1995), S. A. Prahl, A. I. Vitkin, U. Bruggemann, B. C. Wilson, and R. R. Anderson “Determination of optical properties of turbid media using pulsed photothermal radiometry”, Phys. Med. Biol. 37, 1203-1217 (1992)] to study the sub-surface deposition localization of laser radiation, a task which is difficult or impossible for optical methods in tissue due to excessive scattering.
Very recently, dental applications of pulsed PTR focused on the diagnostics of dentin and enamel have been reported as disclosed in D. Fried, W. Seka, R. E Glena, and J. D.
Abrams Stephen H.
Garcia-Hecules Jose Agustin
Mandelis Andreas
Nicolaides Lena
Lateef Marvin M.
Lin Jeoyuh
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