The Effect of Optical Conditioning of Preparations with Scan Spray on Preparation Form.

Objective: CAD/CAM systems require scan spray for chairside sampling of tooth surfaces. However, this leads to alterations of the sprayed preparation and may affect marginal and internal adaption of the restoration. The aim of this study was to define the effect of scan spray on preparation form by evaluating the morphologies and the thicknesses of three different scan sprays. Materials and Methods: The surface morphology of the coatings of different scan sprays (A, B, C) was evaluated by use of a confocal laser scanning microscope. The thicknesses of spray coatings were measured on a glass plate as well as under simulated clinical conditions using a profilometer and a surface digitalisation device. The data were analysed by a 1-way ANOVA (α = .05). Results: The confocal laser scanning microscopy showed rough and irregular formed coating surfaces of all sprays, whereas an increasing numbers of small spray particles were seen from spray A over spray B to spray C. Mean coating thicknesses on the glass plate were: spray A 25.3 Mm, spray B 18.9 Mm and spray C 19.2 Mm. Significant differences were detected between spray A and B (P = .017). Under simulated clinical conditions median coating thicknesses were: spray A 15.5 Mm, spray B 15.0 Mm and spray C 13.3 Mm. A statistically significant difference could be detected only between spray A and C (P = .033). Conclusions: The coatings of the used scan spray systems showed different surface morphologies and exhibited different thicknesses. Consequently, the application of scan sprays affects the precision of the final CAD/CAM restorations. However, the scan sprays under investigation showed acceptable coating thicknesses for clinical use. [ABSTRACT FROM AUTHOR]