Quantitative laser (light) fluorescence method

Quantitative laser (light) fluorescence method
A method that is related to EFF and is attracting considerable interest is the quantitative laser fluorescence technique. At present, QLF can assess only accessible smooth surfaces and is limited to part of the enamel thickness.
The principle for the QLF method is shown in Fig 199. The excitation is performed with blue-green light (488 nm) from an argon ion laser. The fluorescence in the enamel, occurring in the yellow region (approximately 540 nm), is observed through a yellow high-pass filter (520 nm) to exclude the tooth-scattered blue laser light. Dark regions characteristic of demineralization are registered visually or on a photographic film.
For the initial smooth-surface enamel lesions it can detect, the QLF method has a sophisticated computer-based method for measuring changes in lesion size, which is valuable for some applications.
Recently, a commercial laser fluorescence system, Kavo-Diagnodent, has been introduced. This system seems to be efficient for the diagnosis of noncavitated enamel and dentin lesions on buccal, lingual, and occlusal surfaces (Lussi et al, 1999). In particular, this system should be useful in longitudinal caries-preventive studies. 
Table 17 reveals that most of the caries-diagnosing methods discussed are subjective, and this compromises the potential to make accurate measurements of disease activity over time. The potentially objective tools are the separation method used with a local impression, computer-aided radiographic diagnosis, the electrical methods, and QLF.  These tools also have the potential for quantitative measurement, which can be used to aid the diagnosis and determination of carious activity and thus the prognosis. In the past, many of the diagnostic tools have been used only to support a single, dichotomous decision of the presence or absence of disease. Most methods can be used at either the D1 or the D3 threshold. The two exceptions are conventional epidemiologic examinations, which are undertaken at the D3 (dentin caries) level, and the QLF method, which can detect only enamel lesions.
Figure 200 summarizes the performance of the previously discussed methods, in terms of sensitivity and specificity for occlusal and approximal surfaces at diagnostic thresholds D1 (noncavitated enamel lesion) and D3 (dentin lesion). Clearly, no single method will be sufficient for accurate diagnosis of all kinds of carious lesions (see Table 15). 
The relatively poor performance and widespread limitations of the available methods
requires clinicians to seek better and more intelligent ways of using existing methods,
while developing new, more accurate, more appropriate devices.
A target for future investigations would be to explore multiple methods in both
supplementary and adjunctive combinations. To meet the clinical requirements of
most general practitioners, a combination of meticulous clinical visual examination,
radiographs (conventional bitewing radiographs or digitized radiographs), and fiberoptic
transillumination would be adequate.
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hi passerby,thanks for your contmems.about the results for GPA 2007, i guess i am as much in the dark as you. 🙂 i thought i read somewhere that the results will be announced on 5th Dec. 2007, (not sure the NAC or SWF website) but that statement is not there anymore. There doesn’t seem to be much updates on GPA 2007, isn’t it?anyway, i don’t think i win anything, otherwise the organisers should have contacted me by now. cannot be last minute like that. :)i can write to gilbert koh to ask him about it, but it is kind of a bit latish. anyway, thanks for your kind wishes. 🙂

Makes me think of fortuitous evtens. Sky-related. The weatherman can only do so much. Good thing we have writers to chronicle their coming and passing.I like watching lightning streak across the night sky, from my bedroom window. “Like bad fluorescence” is thus very vivid to me.Nature has a way of making us listen, by interrupting or squeezing a slot in our busy schedules. Can’t do anything about it. Then again, power outages can mean quality time for storytelling, or for candlelit dinners. 🙂

gautami,thank you!at this time of the year, you should be gtietng a lot of rain in your country too. :)_soulless_thank you for your comments.i wrote this a long time ago, and what i remembered was, the night was very cold, and this was what i tried to capture in this write.yes, Nature certainly has a way of making us listen. There seems to be more news of her wrath lately.

abt the GPA, they shud haf contacted u by now shud u win right?i dont know. when did greblit koh receive his call to attend the ceremony 2 yrs ago?a week earlier? a day earlier? when is the ceremony anyway. by the way gd luck. http://ysvdrfeai.com [url=http://blnutaabu.com]blnutaabu[/url] [link=http://gxyhsyc.com]gxyhsyc[/link]

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Articles for theme “caries”:
Endoscopic filtered fluorescence methodPitts and Longbottom (1987) explored the use of EFF for the clinical diagnosis of carious lesions and compared results with conventional alternatives on occlusal and approximal sites. This work developed to include the use of an intraoral video system for caries detection, the prototype “videoscope.” Now that commercial intraoral cameras are increasingly available in practices, this may prove to be of practical clinical importance.
Alternating current impedance spectroscopy techniqueA more sophisticated approach to lesion detection and measurement is to characterize the electrical properties of the tooth and lesion by using the ACIST, which scans multiple frequencies. The ACIST is new and has been evaluated only to a limited extent on whole carious teeth. However, the results to date are extremely encouraging, indicating 100% sensitivity and specificity at the D1 level and only a marginal decrease in specificity at the D3 level (Longbottom et al, 1996).
Electrical conductance (fixed frequency) methodElectrical methods of caries diagnosis are not new. There has been recent revival of interest in fixed frequency electrical devices, which show considerable promise for detection of occlusal and approximal lesions. A device is now commercially available in The Netherlands; similar machines were produced in the United States and in Japan some years ago. The electrical detection methods are seen by many as having the greatest potential for significantly improving diagnostic performance in the years to come.
Fiber-optic transillumination methodFiber-optic transillumination is a development of a classic diagnostic aid, advocated some 20 years ago, which has never gained wide acceptance. However, it should be a regularly used tool for diagnosis of caries, in the incisor and premolar regions at least, to supplement clinical examination and bitewing radiographs. Fiber-optic transillumination has enjoyed variable success in studies evaluating its performance, possibly because of failure to appreciate that the technique, like any other, requires an extended learning phase.
Computer-aided radiographic methodComputer-aided radiographic methods exploit the measurement potential of computers in assessing and recording lesion size. In the new Trophy 97 system an artificial intelligence software (Logicon Caries Detector) is integrated: Approximal carious lesions are diagnosed and evaluated with the aid of a unique histologic database, allowing graphic visualization of the size and progression of the lesion (Figs 197a to 197c).At both the D1 and D3 thresholds, computer-aided methods offer high levels of sensitivity for approximal lesions.