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Azerbaycan Saytlari

 »  Home  »  Endodontic Articles 13  »  Location, arrangement and possible function of interodontoblastic collagen fibres in association with calcium hydroxide-induced hard tissue bridges
Location, arrangement and possible function of interodontoblastic collagen fibres in association with calcium hydroxide-induced hard tissue bridges
Results.



Light microscopy with silver staining.
At 3 days, classic argyrophilic von Korff fibres were observed at some distance from the exposure area (Fig.1 A,B).At14 days, thick darkgreyish-purple stained VKF were observed extending from the original dentine, passing through the odontoblasts and projecting out to the central pulp fibres (Fig.1 C, D). The VKF were different from the classic von Korff fibres in their thickness as well as their silver staining intensity. At 21days, VKF extended from the expanded predentine (Fig. 1 E, F). At 30 days, the exposure site was almost completely occluded with a thin layer of a new dentine bridge (Fig.1G). At some distance from the exposure area, argyrophilic VKF were observed with in the new dentine bridge, reaching the material interface (Fig.1 H). At the periphery of the exposure, VKF were observed embedded within the dentine bridge (Fig.1 I). New tubular dentine without VKF was seen following initial dentine bridge formation. VKF were seen extending perpendicularly from the remaining dentine chips (Fig.1 J) at the exposure site. In the absence of dentine chips at the surface of the exposure area, VKF were randomly arranged (Fig.1K). In this area, some defects were observed with in the dentine bridge. A new dentine bridge generally occluded the exposure with increasing time.

Figure 1. (A-K) LM observations by silver staining. (A and B) At 3 days post capping. B is a higher magnification of the rectangular area in'A'. There is no evidence of a zone of necrotic tissue. As light inflammatory cell infiltrate is observed just below the Ca(OH)2 agent (arrow in'A'). Classic von Korff fibres (arrows in B) are observed. (C and D) At14 days after capping. D is a higher magnification of the rectangular area in C. Interodontoblastic VKFs (arrows in D) extend from the original dentine and connect to central pulpal fibres (CPF). (E and F) At 21 days after capping. F is a higher magnification of the rectangular area in E. The distinct expansion of predentine is observed from the periphery of the exposed area (arrow in E). VKFs (arrow in F) extend from the expanded predentine (PD) and connect to the central pulp fibres. (G-K)At 30 days post capping .H-Kare higher magnifications of the rectangular area h-k in G, respectively. The exposure site is almost completely occluded with a thin layer of a new dentine bridge (arrow in G). At the distant site from the exposure area, VKFs are observed within the newly formed dentine bridge, and reach up to its surface (arrow in H). Although classical von Korff fibres (arrowhead in H) are observed, no VKFs are seen in the pulp. At the periphery of the exposed area, VKFs are observed within the dentine bridge (arrow in I). New tubular dentine (_) without VKF was formed following the initially formed dentine bridge. VKFs extend perpendicularly from the remaining dentine chips (_in J) at the surface of the exposed area (arrow in J), whilst VKFs are randomly arranged beneath the chip-free surface (arrow in K). In this area, some defects were also observed (arrowheads in K). A, C, E, G: _40. B, D, F, H-K: x400.

There is no evidence of a zone of necrotic tissue

Immunohistochemistry of type I and III collagen and fibronectin.
At 21 days, immunohistochemical staining for type I collagen and fibronectin were detected in the VKF and fibres of the central pulp (Fig. 2A, C). Immunohistochemical staining for type III collagen was only lightly detected in the VKF and fibres of the central pulp (Fig. 2B). No positive immunohistochemical staining reaction was observed in any negative control sections incubated with normal rabbit IgG (Fig. 2D).

Figure 2. Immunostaining for type I collagen is detected in the VKF and the central pulp fibres (arrows in A). Immunostaining for type III collagen is hardly detected in the VKF, but slightly detected in the central pulp fibres (arrow in B). Immunostaining for fibronectin is detected in the VKF and the central pulp fibres (arrow in C). No positive reaction was observed in negative control sections reacted with normal rabbit IgG (D). x400.

Immunostaining for type I collagen is detected in the VKF and the central pulp fibres

Transmission electron microscopy.
At 14 days, the VKF were seen running in bundles towards the central pulp, passing through the newly formed odontoblastoid cells (Fig. 3A), consisting of two portions; a thick fibril (_240 nm in diameter; Fig. 3B) and a thin fibril (_80 nm in diameter; Fig. 3C). Both fibrils were connected to each other at an angle. VKF presented close morphological relationships with the central pulp broblasts (Fig. 4A). At 21 days, VKF were embedded in the new predentine, presenting a close relationship with broblasts of the central pulp (Fig. 4B). At 30 days, as odontoblastoid cells differentiated, they were seen attaching to each other, and hence VKF lost their close relationship with the central pulp (Fig. 5A) and as the dentine bridge developed, VKF were no longer observed near the odontoblastoid cells (Fig. 5B).

Figure 3. (A-C) TEM of the periphery of the exposure area at 14 days post capping.
(A) AVKF passing through odontoblastoid cells (OB) consists of two portions: the thick fibrillar portion (Tc) and the thin fibrillar portion (Tn). Both portions are connected to each other at an angle (arrow).
(B) Higher magnification of the thick fibrillar portion. These fibrils are ~240 nm in diameter.
(C) Higher magnification of the thinner fibrillar portion. These fibrils are ~80 nm in diameter.
A: x3000. B and C: x20000.

Size of the image files

Figure 4. TEM of the periphery of the exposure area.
(A) At 14 days post capping. Inset shows LM of the corresponding area and VKFs (arrows in inset) are found to pass through odontoblastoid cells (OB) and reach up to the central pulp. VKFs consist of thick fibrillar (Tc) and thin fibrillar (Tn) portions and show a close relationship with central pulp fibroblasts (F) (see arrow).
(B) At 21 days post capping. Inset shows LM of the corresponding area and VKFs (arrows in inset) are embedded in the expanded predentine. AVKF is embedded in the predentine (PD), passing through the odontoblastoid cells (OB), and shows a close relationship with the central pulp fibroblasts (F).
A-B: x2800. All insets x400.

Compression ratios with and without loss of information

Figure 5. (A) TEM of a site distant from the exposure area at 30 days after capping. Inset shows LM of the corresponding area. Odontoblastoid cells (OB) have well-organized cell processes (_and arrowheads in inset) and begin attaching to each other. VKFs (VKF and arrow in inset) reach up to the cell process of the odontoblastoid cells but do not continue to the central pulp.
(B) TEM of the periphery of the exposure area at 30 days after capping. Inset shows LM of the corresponding area and VKFs (arrows in inset) do not reach up to the odontoblastoid cells (OB). Although matrix fibres of predentine are observed (arrowheads), VKFs are no longer observed near the odontoblastoid cells (OB), A-B: Decalcified sections, x2800.All insets x400.

Mean grey values corresponding to the images that resulted from digital subtraction