Histological study of deposited cementum in human deciduous teeth with pathological root resorption.

摘要

Physiological root resorption is a characteristic feature of human deciduous teeth. Pathological root resorption due to apical periodontitis, dental trauma or excessive orthodontic force is also observed in deciduous roots. The root resorption is not continuous, and has resting periods. In the resting period, cementum deposits in resorbed root surface. The deposited cementum in permanent teeth has been reported in detail. However, the deposited cementum in deciduous teeth is unclear. The present study examined apices of roots of human deciduous incisors with apical periodontitis and roots of sound deciduous incisors by light and transmission electron microscopy. Root dentin and original cementum had a severe irregular caved surface. Cementum was partially deposited on the caved root surfaces. The deposited cementum had made the caved root surface relatively flat. The cementum was lax and had some defects. The deposited cementum was belt-like in shape and had a stratified structure. Each layer had various structures consisting of abundant microfibrils and fine granular materials, microfibrils, granular materials, and collagen fibrils, a few fibrils and granular materials and a relatively homogeneous structure. The original cementum had many collagen fibrils, such as intrinsic and extrinsic fibers, and no granular materials or homogeneous structure. Therefore, structure of the deposited cementum was very different from that of original cementum in deciduous teeth and from that of deposited cementum in permanent teeth.