BackgroundPatients with cleidocranial dysplasia (CCD) present a thickend and fibrotic gingiva.PurposeTo the best of our knowledge it was analysed for the first time, whether this is correlated with an increased rate of collagen I in oral mucosa.Patients and methods27 soft tissue biopsies of six CCD-patients and 17 tissue samples of 12 healthy persons were labled with a monoclonal antibody against collagen I and the bound antibodies were detected with alkaline phosphatase-anti-alkaline phophatase-kit. The histological slices were analysed by a digital image recognition software under a fully automated microscope and the rate of collagen I was converted into amounts of grey tones.ResultsThe amount of grey tones reached from 11.909 to 15.319 in the CCD-group, and from 2752 to 12.556 in the control group. The U-Test of Mann, Whitney and Wilcoxon for two independent samples generated a rank sum of 91,50 for CCD-patients, and of 79,50 for the control group. The Z-value was 3,246, the p-value 0,005. “Fisher`s exact test” identified a p-value of 0,0003.ConclusionsThe rate of collagen I in the oral mucosa seems to be increased significantly in CCD. This could explain the typical thick and fibrotic consistency of the gingiva and could be one reason for the delayed or missing dentition.