Dentin resorption mediated by odontoclasts in physiological root resorption of human deciduous teeth

Abstract

Extracted human deciduous teeth undergoing physiological root resorption were fixed with a mixture of formaldehyde and glutaraldehyde and processed for scanning (SEM) and analytical transmission electron microscopy, as well as acid trimetaphosphatase cytochemistry. The granulated tissues, which are rich in multinucleated odontoclasts and capillary vessels, formed various resorption lacunae on the resorbing dentin surfaces. SEM observations of dentin surfaces treated with sodium hypochlorite revealed two types of resorption lacunae: deep, round lacunae in which the peritubular matrix of dentinal tubules was strongly dissolved; and shallow, irregular lacunae with intact peritubular matrix. In trypsin-treated materials, the resorption surfaces were characterized by the presence of numerous collagen fibers in both the peritubular and intertubular matrices, suggesting demineralization of the surface dentin. Odontoclasts were characterized by the presence of abundant mitochondria, perinuclear stacks of Golgi membranes, various lysosomes, numerous endocytotic vacuoles, and a well-developed ruffled border against the resorption lacunae. Most endocytotic vacuoles were distributed in the cytoplasm between the ruffled border and the nuclei. In undemineralized ultrathin sections, the surface dentin of resorption lacunae consisted of collagen fibers and apatite crystals and had a lower packing density than those in unresorbed, deeper dentin. Many apatite crystals were demonstrated to be present in the extracellular channels of the ruffled border and in adjacent endocytotic vacuoles derived from it. Lysosomes located in the perinuclear cytoplasm of odontoclasts contained amorphous dense material and/or a small amount of crystals. An energy-dispersive x-ray microanalysis of apatite crystals in undemineralized sections indicated that the energy spectrum peaks of Ca and P detected from crystals in resorbing dentin were much lower than those in unresorbed dentin. Similarly, lower spectrum peaks of Ca and P were obtained from crystals found in the ruffled border and endocytotic vacuoles of odontoclasts. A slight trace Ca peak also was detected in the amorphous dense material in lysosomes of odontoclasts. The enzyme cytochemistry of lysosomal acid trimetaphosphatase indicated that odontoclasts had intense enzymatic activity in the Golgi membranes, endoplasmic reticulum cisternae, lysosomes, and endocytotic vacuoles. Dense reaction precipitates of enzymatic activity also were found along the dentin surfaces of resorption lacunae occupied by odontoclast ruffled borders.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunohistological Distributions of Fibronectin, Tenascin, Type I, III and IV Collagens, and Laminin during Tooth Development and Degeneration in Fetuses of Minke Whale, Balaenoptera acutorostrata.

“…It is interesting that the whole tooth bud of the minke whale is physiologically absorbed before birth, whereas only the root of the deciduous teeth of other mammalian species is partly absorbed after birth [8,9]. Degeneration of the deciduous teeth in diphyodont animals characterized by resorption of the dental root might be promoted by the physical force of the developing permanent teeth [10].…”

Immunolocalization of vacuolar‐type H+‐ATPase, cathepsin K, matrix metalloproteinase‐9, and receptor activator of NFkB ligand in odontoclasts during physiological root resorption of human deciduous teeth

“…Namely, exposure of collagen fibrils at the resorbing cementum and dentine surfaces, dissolution of the peritubular matrix around dentinal tubules in the resorbing dentine surfaces, and dissolution of the enamel rods and/or their peripheral areas at the resorbing enamel surfaces were clearly demonstrated (Sasaki et al, 1988a;Matsuda, 1992). Therefore, it is apparent that decalcification of the matrices occurs at the resorbing surfaces of these dental hard tissues.…”

“…Past scanning electron microscopic observations have indicated that decalcification of the root dentine surfaces in the resorption lacunae preceded the removal of the organic materials Jones et al, 1984;Sasaki et al, 1988aSasaki et al, , 1990bMatsuda, 1992). Namely, exposure of collagen fibrils at the resorbing cementum and dentine surfaces, dissolution of the peritubular matrix around dentinal tubules in the resorbing dentine surfaces, and dissolution of the enamel rods and/or their peripheral areas at the resorbing enamel surfaces were clearly demonstrated (Sasaki et al, 1988a;Matsuda, 1992).…”

Effect of odanacatib on root resorption and alveolar bone metabolism during orthodontic tooth movement

“…Sasaki et al (1988) suggested that odontoclastic resorption of the tooth root proceeds in a manner similar to that in osteoclastic bone resorption. In contrast, Gonzales et al (2009) found that like osteoclasts, odontoclasts could express CK during orthodontic tooth movements.…”