Design and selection of an instrument for the assessment of roughness related to caries activity

Objectives: For the caries activity-related roughness assessment previous studies have determined a positive association between tactile feeling and surface roughness using the WHO probe. However, its design is not intended for caries/caries activity purposes and there are improvement opportunities. The aim of this study was to choose the most valid, reliable and comfortable of 4 new dental probes’ designs intended for its use in the tactile assessment of surface roughness
Methods: Five experienced examiners in ICDAS-caries detection/assessment discussed instrument improvement possibilities and achieved 4 probe designs with different handle, active part and tip combinations (not disclosed for patent reasons). Agreement was reached after a training and discussion session on the roughness tactile feeling, using 8 known-roughness metal plaques (A: 0.05, B: 0.10, C: 0.20, D: 0.40, E: 0.80, F: 1.60, G: 2.29µm), comparing A vs. others with the 5 instruments, including the WHO probe (5-point Likert Scale). Afterwards, the 5-instrument and 4-plaque (B, D, E, F) order was randomized and each blinded examiner tested independently roughness (5-point Likert Scale) and design comfort (low/moderate/high). Correlation with roughness was determined (Spearman correlation), tactile-assessment intra/inter-examiner agreement was assessed (intraclass-correlation coefficients -ICC) and design comfort was expressed for each probe.
Results: All instruments showed strong tactile-feeling roughness correlation, showing design Nr.-4 best inter/intra examiner ICC and it was also the most comfortable. For all instruments examiners’ intra-examiner reproducibility data was fair-substantial and inter-reproducibility almost perfect (Table).
Conclusions: All designs showed good validity. Examiners were consistent with each other; however more training must be done to achieve higher intra-examiner reliability. Altogether design Nr. 4 was chosen for its good validity, its substantial intra- and almost perfect inter-reproducibility plus its higher comfort sensation. Further studies are needed to test the validity and reliability of the chosen design in human enamel with artificial and/or natural caries lesions.