Comparative35S-sulfate and3H-proline metabolism within the interdental septal bone and adjacent periodontal ligament

Abstract

Tooth movements require rapid remodeling of the periodontal ligament (PDL) and adjacent alveolar bone. Our objective was to compare the regional metabolism of sulfated-glycosaminoglycans (sGAG) within the PDL and adjacent alveolar bone and compare it to the metabolism of collagenous proteins using radioautographic techniques. Rats were injected with either 3 H-proline or 35 S-sulfate and maxillae were removed at 1, 6, and 12 hr 1-7 days later. Silver grains were counted over the PDL and adjacent alveolar bone and the incorporation and removal rates for each radioisotope were determined. In general, net collagenous protein incorporation and removal were greatest within the distal and net sGAG incorporation and removal were greatest within the mesial compartments of the periodontium. The rate of removal of 3 H-proline was significantly greater within the distal alveolar bone surface than the adjacent PDL at all levels (P Ͻ 0.001). In contrast, the rate of removal of 35 S-sulfate was significantly greater in the PDL than within the adjacent mesial surface of the interdental septum at all levels (P Ͻ 0.001). The mesial surfaces of the interdental septum had a slower rate of removal of both isotopes than distal surfaces at all levels (P Ͻ 0.001). Our data suggest significant regional differences in the metabolism of 35 S-sulfate and 3 H-proline within the PDL and alveolar bone, which likely result from the characteristics of the forces produced by the adjacent teeth and may be a factor in the remodeling of the alveolar wall coincident to tooth movement. Key words: alveolar bone; periodontal ligament; glycosaminoglycans; physiological tooth movement; collagenous proteinsThe periodontal ligament (PDL) anchors the root of the tooth to the adjacent alveolar bone and also separates the tooth root from the alveolar wall. The structural components of the PDL include a fibrous component, providing structural support for the teeth, and noncollagenous matrix interspersed between the collagen fibers, which is composed of proteoglycans and glycoproteins (Embery et al., 1995). The fibrous component resists tension forces from adjacent tooth roots and the noncollagenous matrix portion resists the compression forces by forming a biphasic medium with water, giving viscoelastic properties to the PDL (Mow et al., 1984). While there are significant regional differences in the metabolism of collagenous proteins within the PDL, there is little information about the regional metabolism of PDL proteoglycans and glycosaminoglycans. Accurate knowledge of this regional variability