Collagen fibrils of human acellular extrinsic fiber cementum

Tissue-engineering techniques require the accurate description of biologic tissues to recreate these structures using a biomimetic approach. The purpose of this study was to quantify the mean diameter and the distribution of collagen fibrils in acellular extrinsic fiber cementum (AEFC) in human premolars. In human teeth, Sharpey fibers link AEFC to the surrounding alveolar bone. These fibers are composed of type I collagen, and their role is to attach teeth to the surrounding alveolar bone. Although the collagen fibril diameter in periodontal ligament has been studied, the mean diameter of collagen type I fibrils and their size distribution in human AEFC have been poorly described.

Nine human premolars extracted for orthodontic reasons were used for this study, and they were prepared for electron transmission microscopy after decalcification. Specific selection and orientation of the samples allowed us to obtain transverse sections of collagen fibrils of AEFC from four sides of the teeth (i.e., buccal, lingual, mesial, and distal) and from two levels of the roots (i.e., coronal and mid-part). An image analysis process was developed for this study to quantify the mean diameter of collagen fibrils.

This semicomputerized technique allowed the quantification of the diameter of almost 251,000 fibrils. The average diameter varied from 50 to 60 nm, and it was not significantly different based on the surface observed.

Data obtained were compared with literature data on periodontal ligament and other connective tissues. These results could be used to modify the dental-implant surface with synthetic collagen fibrils with similar diameters and distributions rather than the AEFC surface implanted on titanium.