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1 Department of Operative, Preventive and Paediatric Dentistry, Klinik für Zahnerhaltung, University of Bern, Freiburgstrasse 7, CH-3010 Bern, Switzerland; and
2 Institut für Lasertechnologien in der Medizin und Messtechnik (ILM), Ulm, Germany;
* corresponding author, adrian.lussi{at}zmk.unibe.ch
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ABSTRACT |
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 TOP ABSTRACT ORIGIN OF FLUORESCENCEBACKGROUND OF THE DIAGNOdentUSE OF THE DIAGNOdent...USE OF THE DIAGNOdent...CONCLUSIONSREFERENCES |
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KEY WORDS: optical method • DIAGNOdent • caries detection • reproducibility
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ORIGIN OF FLUORESCENCE |
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TOPABSTRACTORIGIN OF FLUORESCENCEBACKGROUND OF THE DIAGNOdentUSE OF THE DIAGNOdent...USE OF THE DIAGNOdent...CONCLUSIONSREFERENCES |
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Carious Enamel
White-spot lesions formed in vitro, without the involvement of bacteria, or very early white-spot lesions formed in vivo do not produce a significant increase in fluorescence compared with sound surfaces (Lussi et al., 2001). Distinct fluorescence of the caries process in more advanced stages (e.g., D2, D3) leads to the assumption that, besides light scattering, bacteria or their metabolites could contribute to the fluorescence of these lesions. To test this hypothesis, bacteria from carious tissue were incubated on blood agar, and the resulting colonies were analyzed by fluorescence microscopy. Interestingly, not only the bacteria colonies but also the surrounding agar showed fluorescence. Agar fluorescence decreased with increasing distance from the colonies, indicating that there were diffusible bacteria metabolites fluorescing on red-light excitation (Hibst et al., 2001). Candidates for such bacteria metabolites could be porphyrins. Porphyrins occur as intermediate steps in the synthesis of heme, and are also produced by several types of oral bacteria. In an earlier work, investigators demonstrated that porphyrins could be extracted from caries lesions and were useful in differentiating caries-affected from sound teeth by violet (406 nm) excited fluorescence (König et al., 1993). Although fluorescence yield is maximal for this short-wavelength excitation, porphyrins were also known to show some fluorescence when excited by red light, as demonstrated by the use of high-performance chromatography with fluorescence detection on extracts from carious tissue from human teeth. Carious material had an intense fluorescence maximum in the red spectral region, containing mainly proto-porphyrin and meso-porphyrin. Thus, molecules that contribute to the signal obtained from caries were identified (Sailer et al., 2001). Whether these are the dominant or even the only fluorophores, or whether there are also other components resulting in red-excited caries fluorescence, has to be evaluated in further research.
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BACKGROUND OF THE DIAGNOdent |
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TOPABSTRACTORIGIN OF FLUORESCENCEBACKGROUND OF THE DIAGNOdentUSE OF THE DIAGNOdent...USE OF THE DIAGNOdent...CONCLUSIONSREFERENCES |
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). With irradiation at 655 nm, there is a decreased fluorescence intensity compared with that achieved at 488-nm excitation, as used for quantitative light fluorescence (QLF). However, a more pronounced decrease for sound surfaces is found compared with carious surfaces, so that caries fluoresces much more strongly. Fig. 1B shows the spectra normalized with respect to the peak intensity. The shapes of the spectra for carious and sound areas are the same across the entire wavelength. Therefore, all fluorescence can be used for differentiation of healthy and diseased tissue, without the need for any spectral analysis (Hibst et al., 2001). The utilization of the total-fluorescence light compensates in part for the lower intensities compared with excitation with shorter wavelengths. Red light, as well as infrared fluorescence radiation, is less-absorbed and -scattered by enamel than is light of shorter wavelengths, so that they penetrate the tooth more deeply (Ertl et al., 1995). It is therefore possible for fluorescence to be measured from underlying carious dentin.
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). The long pass filter absorbs the back-scattered excitation and other short wavelength light and transmits the longer wavelength fluorescence radiation. To eliminate the long-wavelength ambient light also passing through the filter, the laser diode is modulated, and only light showing the same modulation characteristic is registered. Thus, the digital display shows quantitatively the detected fluorescence intensity (in units related to a calibration standard).
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USE OF THE DIAGNOdent IN DAILY CLINICAL PRACTICE |
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TOPABSTRACTORIGIN OF FLUORESCENCEBACKGROUND OF THE DIAGNOdentUSE OF THE DIAGNOdent...USE OF THE DIAGNOdent...CONCLUSIONSREFERENCES |
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). Further research is needed to investigate the exact influence of dehydration on DIAGNOdent readings, especially when caries is longitudinally monitored.
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). This ensures that the tip picks up fluorescence from the slopes of the fissure walls, where the carious process often begins. A rising tone, starting with a value of 10, helps the examiner find the maximum fluorescence value of the site under study.
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gives an overview of the specificity and sensitivity values assessed in different studies. Good intra-examiner reproducibility on occlusal and accessible smooth surfaces was reported in vivo under daily practice conditions (Lussi et al., 2001; Sheehy et al., 2001; Heinrich-Weltzien et al., 2002; Pinelli et al., 2002) and in vitro (Lussi et al., 1999; Attrill and Ashley, 2001; Shi et al., 2001; Lussi and Francescut, 2003) (Table 2). The only investigation which assessed inter-examiner reproducibility on smooth surfaces showed a substantial Kappa value of 0.77 (Pinelli et al., 2002).
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One must keep in mind that the involvement of dentin should not indicate immediate operative intervention in all circumstances. The decision triggering restorative treatment is dependent upon a range of other variables, such as the patient’s case history, fluoride and dietary status, as well as perceived caries activity and the status of the surface. Triggers for restorative intervention in daily practice are therefore at a higher DIAGNOdent value than the ones quoted above (Lussi et al., 2001). In no case should early detection of the caries process be an excuse for early operative intervention, unless this is indicated by other clinical parameters.
This study also showed that a second method has an additional diagnostic yield. Out of the 322 occlusal surfaces, 100 had dentinal caries and were also assessed by visual inspection, bitewing radiography, and the DIAGNOdent. Twenty-nine of these 100 lesions were detected by visual inspection. This number increased to a total of 71 lesions detected when bitewing radiography was used for the second opinion. With laser fluorescence as the second opinion, 92 dentinal lesions were correctly detected (Lussi et al., 2001).
The borderline reading for operative intervention, set at a (peak) value of about 30, reduces the sensitivity of the device but increases its specificity. A higher setting of this "trigger" for operative intervention also represents a safety factor for cases with stained fissures or fissures with calculus. These recommendations were confirmed by others (Heinrich-Weltzien et al., 2001; Anttonnen et al., 2003). Anttonnen and co-workers (2003) reinforced that strict instructions about cut-off values cannot be given; the values given are to be taken as guidelines. The published borderline values obtained in vitro should not be transferred to the in vivo situation. First, the fluorophores change their characteristics as a consequence of the storage of the extracted teeth (unpublished observation), and, second, histological examination of test teeth in vitro is capable of identification of even minute changes in dentin.
Another promising application of the DIAGNOdent is the detection of residual caries during excavation (Reich et al., 1999; Lussi et al., 2000), which should be further evaluated before general recommendations are given. Above all, the reported higher fluorescence of clinically sound cavities close to the pulp needs further investigations.
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USE OF THE DIAGNOdent IN CLINICAL TRIALS OR EPIDEMIOLOGICAL STUDIES |
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TOPABSTRACTORIGIN OF FLUORESCENCEBACKGROUND OF THE DIAGNOdentUSE OF THE DIAGNOdent...USE OF THE DIAGNOdent...CONCLUSIONSREFERENCES |
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), the device should be useful for longitudinal monitoring of the caries process and thus for assessment of the outcome of preventive interventions. The correct assessment of a site is dependent on the correct calibration and tilting procedure, if needed. In contrast to calibration, tilting must be undertaken on each site under study, which takes some seconds. Therefore, this method makes it difficult for large numbers of assessments where time is often a limiting factor. A second prerequisite is the exact repositioning of the device. The previously mentioned very good reproducibility could, in epidemiological or large-scale clinical studies, be hindered by the difficulty of placing the probe on the tooth surface reproducibly. This is most difficult on occlusal surfaces and is probably possible only when a positioning system is coupled with the device. This could be a drawing or a photograph of the site to be inspected and re-inspected during a longitudinal clinical trial. Repositioning for oral or facial smooth-surface lesions should be easier. For approximal surfaces on premolars and molars, repositioning is again harder to achieve, because the tips available today are far too big to be moved around in search of maximum fluorescence. A very thin lance-like tip should be developed to reach the approximal space.
A recently published study (Sheehy et al., 2001) compared the DIAGNOdent with a visual caries-scoring system (Ekstrand et al., 1998). Sheehy et al.(2001) used 170 molar teeth and mimicked the conditions of an epidemiological study. With use of the in vivo cut-off values for the DIAGNOdent (Lussi et al., 2001), both systems were reported to be suitable for epidemiological use. However, it was noted that laser fluorescence did overscore, or the visual system underscored, some lesions.
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CONCLUSIONS |
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TOPABSTRACTORIGIN OF FLUORESCENCEBACKGROUND OF THE DIAGNOdentUSE OF THE DIAGNOdent...USE OF THE DIAGNOdent...CONCLUSIONSREFERENCES |
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FOOTNOTES |
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REFERENCES |
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TOPABSTRACTORIGIN OF FLUORESCENCEBACKGROUND OF THE DIAGNOdentUSE OF THE DIAGNOdent...USE OF THE DIAGNOdent...CONCLUSIONSREFERENCES |
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Anttonnen V, Seppä L, Hausen H (2003). Clinical study of the use of the laser fluorescence device DIAGNOdent for detection of occlusal caries in children. Caries Res 37:17–23.[Medline]
Attrill DC, Ashley PF (2001). Occlusal caries detection in primary teeth: a comparison of DIAGNOdent with conventional methods. Br Dent J 190:440–443.[Medline]
Bamzahim M, Shi X-Q, Angmar-Månsson B (2002). Occlusal caries detection and quantification by DIAGNOdent and electronic caries monitor: in vitro comparison. Acta Odontol Scand 60:360–364.[Medline]
Basting RT, Serra MC (1999). Occlusal caries: diagnosis and non-invasive treatments. Quintessence Int 30:174–178.[Medline]
Côrtes DF, Ellwood RP, Ekstrand KR (2003). An in vitro comparison of a combined FOTI/visual examination of occlusal caries with other caries diagnostic methods and the effect of stain on their diagnostic performance. Caries Res 37:8–16.[ISI][Medline]
Ekstrand KR, Ricketts DN, Kidd EA, Qvist V, Schou S (1998). Detection, diagnosing, monitoring and logical treatment of occlusal caries in relation to lesion activity and severity: An in vivo examination with histological validation. Caries Res 32:247–254.[ISI][Medline]
El-Housseiny AA, Jamjoum H (2001). Evaluation of visual, explorer, and a laser device for detection of early occlusal caries. J Clin Pediatr Dent 26:41–48.[Medline]
Ertl T, Roggan A, Zgoda F (1995). Optische Eigenschaften von Gewebe. In: Angewandte Laserzahnheilkunde. Müller A, Ertl T, editors. Vol. II-3.1.1. Landsberg, Germany: ecomed.
Fleiss IL (1981). Statistical methods for rates and proportions. 2nd ed. New York: Wiley, pp. 212–225.
Heinrich-Weltzien R, Weerheijm KL, Kühnisch J, Oehme T, Stösser L (2002). Clinical evaluation of visual, radiographic, and laser fluorescence methods for detection of occlusal caries. J Dent Children 69:127–132.
Hibst R, Paulus R (1999). Caries detection by red excited fluorescence: investigations on fluorophores. Caries Res 33:295.
Hibst R, Paulus R, Lussi A (2001). Detection of occlusal caries by laser fluorescence. Basic and clinical investigations. Med Laser Appl 16:205–213.
König K, Hibst R, Meyer G, Flemming G, Schneckenburger H (1993). Laser-induced autofluorescence of carious regions of human teeth and caries-involved bacteria. SPIE 1880;125–131.
Lussi A (2000). Laserinduzierte Fluoreszenz zur Erkennung der Okklusalkaries. Erste in vivo—resultate. Acta Med Dent Helv 5:15–19.
Lussi A, Francescut P (2003). Performance of conventional and new methods for the detection of occlusal caries in deciduous teeth. Caries Res 37:2–7.[Medline]
Lussi A, Imwinkelried S, Pitts NB, Longbottom C, Reich E (1999). Performance and reproducibility of a laser fluorescence system for detection of occlusal caries in vitro. Caries Res 33:261–266.[ISI][Medline]
Lussi A, Francescut P, Achermann F, Reich E, Hotz P, Megert B (2000). The use of the DIAGNOdent during cavity preparation. Caries Res 34:327–328.
Lussi A, Megert B, Longbottom C, Reich E, Francescut P (2001). Clinical performance of a laser fluorescence device for detection of occlusal caries lesions. Eur J Oral Sci 109:14–19.[Medline]
Pereira AC, Verdonschot EH, Huysmans MCDNJM (2001). Caries detection methods: can they aid decision making for invasive sealant treatment? Caries Res 35:83–89.[Medline]
Pinelli C, Campos Serra M, De Castro Monteiro Loffredo L (2002). Validity and reproducibility of a laser fluorescence system for detecting the activity of white-spot lesions on free smooth surfaces in vivo. Caries Res 36:19–24.[Medline]
Reich E, Berakdar M, Netuschil L, Pitts N, Lussi A (1999). Clinical caries diagnosis compared to DIAGNOdent® evaluations. Caries Res 33:299.
Sailer R, Paulus R, Hibst R (2001). Analysis of carious lesions and subgingival calculi by fluorescence spectroscopy. Caries Res 35:267.
Sheehy EC, Brailsford SR, Kidd EAM, Beighton D, Zoitopoulos L (2001). Comparison between visual examination and a laser fluorescence system for in vivo diagnosis of occlusal caries. Caries Res 35:421–426.[Medline]
Shi X-Q, Welander U, Angmar-Månsson B (2000). Occlusal caries detection with KaVo DIAGNOdent and radiography: an in vitro comparison. Caries Res 24:152–258.
Shi X-Q, Tranaeus S, Angmar-Månsson B (2001). Comparison of QLF and DIAGNOdent for quantification of smooth surface caries. Caries Res 35:21–26.[ISI][Medline]
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