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Table 2. Criteria used in the histological examinations Score Criteria used in the Downer histological examination [Downer, 1975] Criteria used in the ERK histological examination [Ekstrand et al., 1997] 0 No enamel demineralisation or a narrow surface zone of opacity (edge phenomenon) 1 Enamel demineralisation limited to the outer 50% of the enamel layer 2 Demineralisation involving the inner 50% of the enamel, up to the enamel-dentine junction No enamel demineralisation or a narrow surface zone of opacity (edge phenomenon) Enamel demineralisation limited to the outer 50% of the enamel layer Demineralisation involving between 50% of the enamel and outer third of the dentine 3 Demineralisation involving the outer 50% of the dentine Demineralisation involving the middle third of the dentine 4 Demineralisation involving the inner 50% of the dentine Demineralisation involving the inner third of the dentine Histological Preparation For histological examination the roots were resected from the teeth just apical to the cementum-enamel junction. The crowns of the teeth were then dehydrated by serially submerging them in increasing concentrations of alcohol solutions (40, 60, 80, 100, 100%) for 12 h in each. This progressive dehydration of the tooth reduced damage and facilitated penetration of an alcohol/light cure acrylic (1: 1) mix (Technovit 7200 VLC, Heraeus Kulzer, Germany) into which the tooth was placed for 36 h. The acrylic was then light cured for 10 h (Histolux, Exakt, Germany). To further reduce section damage and aid mounting of the specimen for the three-dimensional cutting technique [Stachniss, 2005], the teeth underwent a second stage of embedding in an acrylic tube which was filled with acrylic (Technovit 7200 VLC) to completely cover the tooth. Because visual access to the occlusal surface and investigation sites was now impaired, an accurate coordinating system was required to correctly assign each section to the corresponding position within the tooth. To achieve this, the cut root face was placed on a triangle of foil of known dimensions (a = 9 mm), height (b = 18 mm) and angle ( = 63.5°) prior to placement of the specimen in the acrylic tube and the second embedding stage ( fig. 1 ). The base (a) of the triangle was aligned with the mesial surface of the tooth and ran parallel with the occlusal surface. The embedded tooth together with the foil triangle were then serially sectioned in a buccolingual direction. Each embedded section therefore contained a section of the coloured foil in the form of a distinct line in relation to the cut root face. If the length of the coloured line at the base of the section was ML ( fig. 1 ), the formula H = 2(a – ML) gives the height (H) or y coordinate of the section. The correct sections could then be determined for each investigation site, using the x coordinate recorded on the digital photograph of the occlusal surface. Prior to histological examination the sections were ground and polished on waterproof silicon carbide paper (1,200, 2,400 and 4,000 grit; Hermens or Wirz, Germany) to a specimen thickness of 200 ( 8 30) m (checked with a digital micrometer; Müller, Germany). In total 11–15 sections were produced per crown and 1–4 sections were available to view for each investigation site. Histological Examination For each investigation site the selected sections were examined by all 4 examiners using a binocular microscope (Wild Heerbrugg AG, Gais, Switzerland) using ! 16 magnification and reflected light. Two different histological classification systems [Downer, 1975; Ekstrand et al., 1997] were used to record caries severity at each investigation site and this was carried out blindly to the other examiners ( table 2 ). Up to 4 sections were available which could be assigned to each investigation site. A histological score was given to each section and the worst/deepest score was taken as the definitive score for further analysis. For each investigation site and each histological classification system the results from all 4 examiners were then compared to achieve a consensus score for each site. Where 3 or more examiners agreed on the histological score, this was taken as consensus. Where there was greater disagreement, the sections were reviewed by all examiners and after discussion a consensus was reached. Caries extent was based upon colour and structural changes in enamel and dentine, with emphasis being placed on differentiating carious changes from protective changes of the pulp-dentine complex, such as tubular sclerosis and reactionary dentine formation. Data Management and Statistical Evaluation Both the ICDAS-II and histology scores were recorded on special sheets and later transferred to an Excel table. Multiple investigation sites on a single tooth do not represent statistically independent data. To ensure that statistical analysis was based on independent data, one site was randomly chosen (SPSS 14.0) for each tooth with more than one investigation site, and used as the score for that tooth. For the ICDAS-II scores, interexaminer reproducibility was calculated for all pairs of examiners and intra-examiner reproducibility was calculated for the trained examiners using weighted Cohen’s kappa (using linear weights). For each examiner, the relationship between the visual scoring system and both of the histological scoring systems (Downer and ERK) was assessed using the Spearman rank correlation. The consensus Downer histology was used to calculate sensitivity and specificity at the D1 and D3 diagnostic threshold. At the D1 diag- 82 Caries Res 2008;42:79–87 Jablonski-Momeni /Stachniss /Ricketts / Heinzel-Gutenbrunner /Pieper
nostic threshold all histological scores 1–4 were classed as caries and each ICDAS-II cut-off was used to calculate sensitivity and specificity for each examiner. Similarly for the D3 diagnostic threshold histological scores 3 and 4 were classed as caries only and sensitivity and specificity calculated at each ICDAS-II cutoff. The ERK histology, using the classification 2–3 as a histological threshold, was also used to calculate sensitivity and specificity for each ICDAS-II cut-off. Using these sensitivity and specificity values ROC analyses were carried out at the D1, D3 and ERK 2–3 thresholds for each examiner. Table 3. Inter- and intra-examiner reproducibilities for visual ICDAS-II examinations Weighted kappa examiner 1 examiner 2 examiner 3 examiner 4 Examiner 1 0.82 0.74 0.77 Examiner 2 0.78 a 0.70 0.74 Examiner 3 0.74 a 0.62 Examiner 4 0.83 a a Intra-examiner data in italics. R e s u l t s Initially, 100 teeth and up to 4 sections per independent investigation site were planned for investigation, but, owing to section damage on some teeth and to some not being scored by all examiners, only 93 investigation sites and 201 corresponding sections were available for analysis (14 investigations sites had 1 section, 54 had 2 sections, 21 had 3 sections and 4 had 4 sections). The number of sections per investigation site was dictated by the size and spread of the lesion. Three or more examiners agreed on the histological assessment in 89% of investigation sites when using the Downer classification and 84% of investigation sites when using the ERK classification. The interexaminer weighted kappa values were 0.66–0.75 for the Downer classification and 0.60–0.74 for the ERK classification. Where disagreement occurred, a consensus decision was made following discussion and this was used in subsequent analyses. Table 3 shows the intra- and interexaminer reproducibilities (kappa values) for the visual ICDAS-II examinations. Table 4 shows the distribution of ICDAS-II data crosstabulated with both the Downer and ERK histological scores (consensus) for the independent investigation sites included in this study for the reference examiner. Table 5 Table 4. Cross tables showing the relationship between the ICDAS-II scores for examiner 1 and the consensus decision for Downer and ERK histological classification systems for the independent data ICDAS-II 0 1 2 3 4 5 6 Downer histological score 0 15 7 0 0 0 0 0 22 1 4 4 4 1 0 0 0 13 2 2 4 6 1 0 1 1 15 3 0 5 5 14 6 6 0 36 4 0 0 0 0 2 4 1 7 Total 21 20 15 16 8 11 2 93 ERK histological score 0 15 7 0 0 0 0 0 22 1 4 4 4 1 0 0 0 13 2 2 5 10 9 2 2 1 31 3 0 4 1 6 4 6 0 21 4 0 0 0 0 2 3 1 6 Total 21 20 15 16 8 11 2 93 Table 5. Spearman’s correlation coefficients: visual versus histological scores Spearman’s correlation coefficient examiner 1 examiner 2 examiner 3 examiner 4 all examiners Visual versus Downer histological scores 0.60 0.72 0.59 0.48 0.58 Visual versus ERK histological scores 0.58 0.68 0.54 0.43 0.54 Reproducibility/Accuracy of a Method for Caries Detection Caries Res 2008;42:79–87 83
Page 1 and 2: Original Paper Caries Res 2008;42:7
Page 3: ML b ML ML H a ML Fig. 1. Occlusal
Page 7 and 8: ERK 2-3 diagnostic threshold AUC (S
Page 9: Pitts N: ‘ICDAS’ - an internati

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