Synthesis of alveolar bone Sharpey's fibers during experimental tooth movement in the rat

Abstract

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).

Where tendons and ligaments meet bone: attachment sites (‘entheses’) in relation to exercise and/or mechanical load

“…Yes, some tendons/ligaments certainly do have Sharpey's fibres – notably fibrous entheses in regions where there is substantial cortical bone, at the sites where the periodontal ligament is attached to cementum and alveolar bone (Raspanti et al. 2000) and at the sites of surgical reattachment of tendons and ligaments to the skeleton (Johnson, 2005). Yet, a great many tendons and ligaments attach to areas of bone where there is virtually no cortex (short bones and the epiphyses and apophyses of long bones).…”

LPS Induces Greater Bone and PDL Loss in SPARC-null Mice

“…An increase in SF is indicative of bone remodeling (Cochran et al, 2003;Diedrich et al, 2003;Johnson, 2005). SP/ ON-null mice have decreased trabecular bone formation (Boskey et al, 2003) and diminished deposition of collagen (Bradshaw et al, 2003a(Bradshaw et al, ,b, 2009Trombetta and Bradshaw, 2010).…”

“…SF participate in the transmission of forces from tooth to bone. A reduction in SF is associated with increased bone resorption (Johnson, 2005). Therefore, SF are considered essential for the establishment of a functional PDL.…”

Comparing physicochemical properties of printed and hand cast biocements designed for ligament replacement

“…3 Although both soft and hard tissue exhibit similar tensile properties, 4 it is the elastic modulus mismatch, where the elastic modulus of bone is ten times that of tendons 3 which is the primary reason direct surgical reattachment of tendons and ligaments to bone often fail. 5 Current methods of repair using synthetic materials include: sutures; fixation plates; silastic sheets; carbon fibres; and fibrin glues, however, a lack of a graded interface region induces common failure of these repair methods. Furthermore, the lack of graft availability, donor site morbidity, poor healing, graft failure requiring further surgery or a lifelong altered gait add to the disadvantages of current methods of tendon and ligament repair and alternative methods are required.…”