Synthesis of Sharpey’s Fiber Proteins within Rodent Alveolar Bone

Physiologic drift of teeth requires remodeling alveolar bone at the tooth socket wall. Remodeling must be regulated so that collagenous attachments are maintained as new tooth positions are established. Thus, alveolar remodeling must occur coincident to remodeling of the Sharpey’s fibers which are embedded within that bone. Studies suggest that these fibers are severed at resorptive sites on the alveolar wall and continuity with periodontal ligament fibers is reestablished by splicing, de novo synthesis, or adhesion to the base of the Howship’s lacuna at the alveolar wall; however, little information is available concerning the mechanisms of these events. This article reviews types of periodontal Sharpey’s fibers and quantifies and compares protein deposition into these fibers with that of adjacent bone. Effects of orthodontic tooth movement on the protein incorporation into the fibers were also studied. Coincident to orthodontic tooth movement, sites of bone matrix deposition (without previous resorption) and resorption/reversal were evident. At sites of deposition, periodontal ligament fibers were passively entrapped as Sharpey’s fibers by the new bone matrix. Incorporation of 3H-proline-labeled proteins into bone matrix adjacent to Sharpey’s fibers was significantly increased; however, radiolabeled protein incorporation into the Sharpey’s fiber was not affected. At resorption/reversal sites, Sharpey’s fibers had been severed and periodontal ligament fiber attachments to the alveolar wall were becoming reestablished. Incorporation of radiolabeled proteins into both Sharpey’s fibers and adjacent matrix was significantly increased at these sites. Thus, movement of adjacent teeth affect the relative metabolism of these fibers, assuring adequate support of the tooth during its relocation.