The presented work describes the development and verification of a novel optical, powder-free intra-oral scanner based
on chromatic confocal technology combined with a multifocal approach. The proof of concept for a chromatic confocal
area scanner for intra-oral scanning is given. Several prototype scanners passed a verification process showing an
average accuracy (distance deviation on flat surfaces) of less than 31μm ± 21μm and a reproducibility of less than 4μm ±
3μm. Compared to a tactile measurement on a full jaw model fitted with 4mm ceramic spheres the measured average
distance deviation between the spheres was 49μm ± 12μm for scans of up to 8 teeth (3- unit bridge, single Quadrant) and
104μm ± 82μm for larger scans and full jaws. The average deviation of the measured sphere diameter compared to the
tactile measurement was 27μm ± 14μm. Compared to μCT scans of plaster models equipped with human teeth the
average standard deviation on up to 3 units was less than 55μm ± 49μm whereas the reproducibility of the scans was
better than 22μm ± 10μm.
Various test objects, plaster models, partially equipped with extracted teeth and pig jaws representing various clinical situations of tooth preparations were used for in-vitro scanning tests with an experimental intra-oral scanning system based on chromatic-dispersive confocal technology. Scanning results were compared against data sets of the same object captured by an industrial μCT measuring system. Compared to μCT data an average error of 18 – 30 μm was achieved for a single tooth scan area and less than 40 to 60 μm error measured over the restoration + the neighbor teeth and pontic areas up to 7 units. Mean error for a full jaw is within 100 – 140 μm. The length error for a 3 – 4 unit bridge situation form contact point to contact point is below 100 μm and excellent interproximal surface coverage and prep margin clarity was achieved.