Int. J. Environ. Res. Public Health 2009, 6 2503 - Examination of 40 subjects at two different points in time as part of a general screening. The examinations were done by separate examiners (I.G., S.B., H.S.). - Evaluation of the criteria under field conditions for 12-year olds as part of the standard school examination in a provincial town of the Philippines (R.H.-W.). - Application and assessment in a dental office (T.O.). - On-going review of the criteria set as part of patient care in university hospitals and the training of under- and postgraduate students and dentists (J.K., R.H.-W.). 2.4. Validation and Reproducibility Testing of UniViSS on Occlusal Surfaces For testing the validity of UniViSS a sample of 65 sound and mostly non-cavitated third molars was selected from a pool of teeth extracted for surgical or orthodontic reasons. Only permanent molars without sealants, fillings, cavitations, approximal and/or buccal/lingual caries lesions and developmental defects were included. All teeth were independently categorized according to the newly developed UniViSS criteria by two dentists. All diagnoses were counterchecked one week later to form a consensus diagnosis for each surface. In case of different findings, both examiners discussed the discordant results and came to an agreement. The histological validation included the sectioning of all teeth with a microtome saw (Mikrotrenn MT 1-78-03, Hofer, Switzerland) to find the maximum caries extension of the lesion. To assess the caries extension more precisely all slices were examined under a light microscope at sixteen fold magnification (Stemi SV11 stereomicroscope, Zeiss, Oberkochen, Germany). The slice with the greatest caries extension for each specimen was identified, digitally photographed and stored. Each caries lesion was classified according to the criteria by Marthaler [20]. The diagnosis for each specimen was counterchecked one week after the initial examination. In case of different findings regarding the caries extension, the examiners discussed their discordant measures to reach an agreement. Both examiners were blinded to the visual appearance of each surface. The validity of UniViSS was determined by calculating the sensitivity (SE), specificity (SP) and the Az values under the ROC curves for the caries detection level (D0 vs. D1-4) as well as for the dentine caries detection level (D0-2 vs. D3-4). For testing intra- and inter-examiner reproducibility the inaugurator of UniViSS (J.K.) as well as two other dentists (D1, D2) investigated 60 sound and non-cavitated extracted third molars under standardized in vitro conditions. Prior to the beginning of all measurements all examiners were introduced to the use of UniViSS and received extensive theoretical and practical training. Each evaluation cycle was repeated after a minimum interval of two weeks to safeguard the blindness of each investigator between both measurement cycles. Weighted Kappa values (wK) and the percentage of coincident readings were calculated as measure of agreement for categorical data to determine the intra- and inter-examiner reproducibility. The reproducibility can be assessed as low for wK below 0.40, moderate for wK between 0.41 and 0.60, good for wK between 0.61 and 0.80 and excellent for wK between 0.81 and 1.00.