μct100 scanner

Rats were decapitated, and molar samples on the left and right sides of the maxilla were scanned with a μCT100 scanner (SCANCO Medical AG, Wangen-Brüttisellen, Switzerland). Ground sections of the teeth in the coronal and sagittal planes were made (Figure 1a) based on the images of the molars, where the mean thickness of enamel and dentin in Sprague–Dawley rats was determined to be 1 mm.

For each treatment, twelve representative, fully dried primary spikes were selected for scanning and placed in plastic holders (34 mm diameter, 70 mm height). The majority of the spikes were too tall to fit in the holders so they were cut into two pieces and each scanned separately. Pieces of thermoplastic starch were used to eliminate sample movement while scanning. Sample preparation and loading into the scanner takes around 30 min per 12 samples and after this time there is no more user input. The twelve holders were loaded into the sample changing carousel of a μCT100 scanner (Scanco Medical, Switzerland). This scanner has a cone beam X-ray source with power ranging from 20 to 100 kVp (pre-set and calibrated for 45, 55, 70, 90 kVp) and a detector consisting of 3072 × 400 elements (48 µm pitch) and a maximum resolution of 1.25 µm. The samples can be positioned at different distances from the X-ray source greatly improving resolution while keeping scanning time to a minimum. Spikes were scanned with the X-ray power set at 45 kVp and 200 µA with an integration time of 200 ms. Each spike was ~ 1000 slices (51 slices per stack), 125 projections/180° were taken and a binning of 6 was used. Output images were produced with a 0.2 megapixel (512 × 512) resolution (68.8 µm/pixel) in a proprietary ISQ file type format (Scanco Medical, Switzerland).