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International Poster Journal of Dentistry and Oral Medicine



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Int Poster J Dent Oral Med 5 (2003), No. 3     15. Sep. 2003

Int Poster J Dent Oral Med 2003, Vol 5 No 03, Poster 184

Detection of Smooth Surface Lesions by QLF and Visual Inspection - An in vivo Comparison

Language: English

Prof Dr. Roswitha Heinrich-Weltzien, Dr. Jan Kühnisch, Susanne Ifland, Prof. Dr. Dr. Lutz Stößer
Poliklinik für Präventive Zahnheilkunde, ZZMK, Friedrich-Schiller Universität Jena;
PhD Sofia Tranæus
Department of Cariology and Endodontology, Institute of Odontology, Karolinska Institutet, Stockholm;
PhD Monique van der Veen
Department of Cariology Endodontology Pedodontology, ACTA, Amsterdam, The Netherlands.

49th Congress of the European Organisation of Caries Research (ORCA)
Naantali, Finland


Evaluation of the detection of smooth surface lesions by the Quantitative Light-induced Fluorescence (QLF) method in comparison with visual inspection (VI)

Fig. 1:
Initial carious lesions on smooth surfaces - clinical situation
Fig. 2:
Initial carious lesions on smooth surfaces - QLF image

Material and Methods

  • 34 fifteen-year-old adolescents were involved in the study.
  • Visual examination of 918 buccal and 917 lingual surfaces with aid of compressed air and magnifying glass (3.5x) after professional tooth-cleaning.
  • Capturing of fluorescence images of all smooth surfaces by a QLF\\clin.
  • Images were stored and analysed with an Inspektor QLF 2.00 programmes.
Fig. 3:
Area of enamel lesions detected by QLF and VI
  • QLF images were analysed blind by two examiners, presence or absence of a lesion was not marked on the fluorescence images.
  • Determination of fluorescence loss (DeltaF) and area (A) of the lesion (mm2) and DeltaQ (DeltaF x A).
  • Surfaces scored as sound, filled or with frank lesions by both methods were excluded.
  • Mann-Whitney U-test was used for statistical analysis; the confidence interval of 95% was chosen.


1. Table 1 presents the findings of the caries status of 1835 smooth surfaces assessed in the 15-year-olds with a caries experience of 7.7+5.8 D3-4MFS.

Table 1: Caries status of smooth surfaces
  Sound D1-2 D3-4F Total
Buccal 527 352 39 918
Lingual 745 137 35 917
Total 1272 489 74 1835

2. 17.8% of the buccal/lingual enamel lesions were detected by VI, 53.8% by VI/QLF and 28.4% by QLF, respectively. (Table 2).

Table 2: Diagnostic outcome of detection of smooth surfaces lesion by QLF and VI
  Visual Visual + QLF QLF Total
Bukkal 76 213 (61%) 63 352
Lingual 11 50 (37%) 76 137
Total 87 (17,8%) 263 (53,8%) 139 (28,4%) 489

3. The parameters A, delta-F and delta-Q between smooth surface lesions recorded by both VI/QLF, and QLF only were significantly different.

Fig. 4a:
Fluorescence loss of enamel lesions detected by QLF and VI
Fig. 4b:
Fluorescence loss of enamel lesions detected by QLF and VI

4. QLF was able to detect smaller enamel lesions with smaller fluorescence loss than lesions recorded by VI/QLF together.

5. Lesion detection by QLF was limited in cases of partially erupted and plaque covered surfaces, and in patients with poor oral hygiene associated with reduced surface size caused by gingivitis (Table 3). Small focal depth on lingual surfaces was a further confounding factor.

Table 3: Only visual detected enamel lesions
QLF-images N %
Plaque covered surface 20 23,0
Image out of focus 14 16,1
Image very bright 9 10,3
Gingivitis 44 50,6
Total 87 100

Fig. 5:
Initial carious lesion detected by QLF.
Fig. 6:
Plaque covered initial carious lesion.

Fig. 7:
Fig. 8:
Alter 2 Month
Fig. 9:
Alter 4 Month
Reduction of Ggingivitis in follow of preventive intervention measures.


QLF is a sensitive method for quantification of visual undetected incipient caries lesions. Confounding factors like gingivitis, plaque and the eruption stage of a tooth may obscure lesion detection and should be controlled.


This Poster was submitted by Prof. Dr. Roswitha Heinrich-Weltzien.

Correspondence address:
Prof. Dr. Roswitha Heinrich-Weltzien
Poliklinik für Präventive Zahnheilkunde
Friedrich-Schiller Universität Jena
Nordhäuserstr. 74
99089 Erfurt