There is little information concerning the effects of tooth movement on the relative synthesis of bone matrix and Sharpey's fiber collagenous proteins. The purpose of this study was to investigate this situation using radioautographic techniques. The maxillary first molar tooth in rats was tipped toward the midline using an appliance and the animals were injected with 3 H-proline after 3 days and sacrificed 24 hr later. Maxillae were sectioned and silver grain proportional areas (grain density/5,000 m 2 ) evaluated over Sharpey's fibers and adjacent alveolar bone matrix using computerized densitometry and histomorphometric techniques. These data were compared to a group of untreated animals by Fisher's exact test. At depository surfaces of experimental tissues, the silver grain proportional area over bone matrix was significantly greater than over Sharpey's fibers (P Ͻ 0.05) and control bone matrix (P Ͻ 0.01). The silver grain proportional area over Sharpey's fibers was not different between the groups. At resorptive surfaces, the silver grain proportional area over both bone matrix and Sharpey's fibers was significantly greater in experimental tissues compared to controls (P Ͻ 0.01). Thus, movements of adjacent teeth affect both the quantity and ratios of collagenous protein incorporation into Sharpey's fibers and adjacent alveolar bone, which is dependent on the intensity and characteristics of the force. © 2005 Wiley-Liss, Inc.Key words: Sharpey's fibers; experimental tooth movement; alveolar bone; rat Tooth movement occurs by alveolus translocation, which is a unique type of remodeling, featuring simultaneous bone formation and resorption on opposite sides of the alveolus. Taken together, these processes result in drift of the entire alveolus in parallel to tooth drift to maintain tooth support (Roberts et al., 1981) and require remodeling of the principal fibers of the periodontal ligament (PDL), alveolar bone matrix, and the embedded Sharpey's fibers.Tooth movement produces stress/strain forces within the PDL, which are transferred to the alveolus (Tanne et al., 1987;Katona et al., 1995;Middleton et al., 1996;Puente et al., 1996;Tamatsu et al., 1996) and become transduced into a cellular response within the periodontium. In response to these forces, bone is deposited on the alveolar wall in regions of tension, and bone resorption occurs at sites experiencing pressure forces (Macapanpan et al., 1954;Waldo and Rothblatt, 1954;Zaki and Van Huysen, 1963; Azuma, 1970;Lopez Otero et al., 1973;Heller and Nanda, 1979;Yamasaki et al., 1980;Lilya et al., 1984;Martinez and Johnson, 1987; Chao et al., 1988;Lee, 1990; King et al., 1991a, b;King and Keeling, 1995; Ashizawa and Sahara, 1998). Rat molar teeth drift in a distal direction under physiologic conditions because the alveolus maintains net bone deposition on its mesial surface and net bone resorption on its distal surface (Sicher and Weinmann, 1944).