The tooth attachment mechanism defined by structure, chemical composition and mechanical properties of collagen fibers in the periodontium

Abstract

In this study, a comparison between structure, chemical composition and mechanical properties of collagen fibers at three regions within a human periodontium, has enabled us to define a novel tooth attachment mechanism. The three regions include 1) the enthesis region: insertion site of periodontal ligament fibers (collagen fibers) into cementum at the root surface, 2) bulk cementum and 3) the cementum dentin junction (CDJ). Structurally, continuity in collagen fibers was observed from the enthesis, through bulk cementum and CDJ. At the CDJ the collagen fibers split into individual collagen fibrils and intermingled with the extracellular matrix of mantle dentin. Under wet conditions, the collagen fibers at the three regions exhibited significant swelling suggesting a composition rich in polyanionic molecules such as glycosaminoglycans. Additionally, site-specific indentation illustrated a comparable elastic modulus between collagen fibers at the enthesis (1 -3 GPa) and the CDJ (2 -4 GPa). However, the elastic modulus of collagen fibers within bulk cementum was higher (4 -7 GPa) suggesting presence of extrafibrillar mineral.It is known that the tooth forms a fibrous joint with the alveolar bone which is termed a gomphosis. Although narrower in width than the periodontal ligament space, the hygroscopic CDJ can also be termed as a gomphosis; a fibrous joint between cementum and root dentin capable of accommodating functional loads similar to that between cementum and alveolar bone. From an engineering perspective, it is proposed that a tooth contains two fibrous joints that accommodate the masticatory cyclic loads. These joints are defined by the attachment of dissimilar materials via graded stiffness interfaces, such as; 1) alveolar bone attached to cementum with the PDL and 2) cementum to root dentin with the CDJ. Thus, through variations in concentrations of basic constituents, distinct regions with characteristic structures and graded properties allow for attachment and the load bearing characteristics of a tooth.

The Collagen Binding Protein Cnm Contributes to Oral Colonization and Cariogenicity of Streptococcus mutans OMZ175

“…Similarly, ex vivo tooth-binding assays demonstrated that Cnm ϩ strains outcompeted their Cnm Ϫ variants in adherence to root and dentin sections, but not to enamel, emphasizing the specificity of Cnm for collagen-rich substrates. The dentin organic matrix is composed of approximately 90% collagen type I, and surrounding tissues, such as the cementum, periodontal ligament fibers, and roots, are also rich in collagen (17). These tissues are ordinarily shielded from the oral flora either by protective hard surfaces (enamel) or by soft tissues (gingiva).…”

“…Left untreated, further demineralization of the enamel and extension of the lesion expose the underlying dentin, presenting collagen and other, additional substrates for bacterial colonization (15,16). Other oral tissues, such as the cementum, root, and periodontal ligament fibers, are also rich in collagen (17) and, if exposed to the oral environment, may be vulnerable to attachment and colonization by microbes equipped with collagen-binding adhesins (13,(18)(19)(20). In S. mutans, SpaP, WapA, Cnm, and Cbm have been identified as collagen-binding adhesins, but thus far, only SpaP has been examined for its role in attachment to dentin (10).…”

Gradient biomaterials and their influences on cell migration

“…The compression strength differs from 133 MPa in the mid-femur to 6.8 MPa in the proximal femur, while the modulus of elasticity decreases from 17 to 0.441 GPa [31]. Teeth also contain gradients in composition and mineral density, leading to gradients in mechanical properties [32].…”

Mechanical Function of a Complex Three‐Dimensional Suture Joining the Bony Elements in the Shell of the Red‐Eared Slider Turtle

“…One prominent example of such a joint is the periodontal ligament, which serves as an interface between the tooth and its bony socket. [24] An investigation of the complex mechanical performance under load of the tooth-bone unit is described elsewhere in this issue. [25] The sutures of the shell of the turtle are very similar in many respects to the sutures found in the skull of vertebrates.…”