Immunohistochemical characterization of noncollagenous matrix molecules on the alveolar bone surface at the initial principal fiber attachment in rat molars

Quantitative characterizations of the Sharpey's fibers of rat molars

BACKGROUND AND OBJECTIVE

The Sharpey's fibers of periodontal ligament (PDL) anchor the PDL to alveolar bone and cementum and are essential for the function of PDL. While qualitative analyses of the Sharpey's fibers have been widely explored, a comprehensive quantitative characterization of the Sharpey's fibers is not available. In this work, we selected rat molars as a model and comprehensively characterized the PDL Sharpey's fibers (diameter, density, length, embedding angle, and insertion angle).

MATERIALS AND METHODS

A total of 24 rat mandibular molars, eight maxillary first molars, and their surrounding alveolar bone were harvested, fixed, rendered anorganic and observed under scanning electron microscopy (SEM). The mandibles and maxillae (n = 4) were harvested, processed, sectioned, and stained with Sirius red for histological observation. SEM images were used for quantitative analyses of diameters and densities of the Sharpey's fibers, while Sirius red staining images were used to measure lengths and angles. The Sharpey's fibers were comprehensively characterized in terms of positions (cervical, middle, and apical thirds), PDL fiber groups (alveolar crest, horizontal, oblique, apical, and interradicular groups), sides (cementum and bone sides), and teeth (mandibular first, second, third molars, and maxillary first molar).

RESULTS

Our results showed that the characteristic parameters of the Sharpey's fibers varied in different positions, fiber groups, sides, and teeth. Specifically, the median diameter of the Sharpey's fibers on the bone side was significantly greater than that on the cementum side, while the median density of the Sharpey's fibers on the bone side was significantly lower than that on the cementum side, regardless of the positions and teeth. For the same tooth, the median length of the embedded Sharpey's fibers on the bone side was more than two times greater than that on the cementum side. Among all fiber groups, the alveolar crest group had the maximum length of the Sharpey's fibers on the bone side and the minimal length of the Sharpey's fibers on the cementum side. There is an approximate 5-15° difference between the embedding angle and the insertion angle in each group. The oblique group had the smallest embedding angles on both the bone and cementum sides.

CONCLUSION

This study provides a comprehensive and quantitative characterization of the Sharpey's fibers using rat molars as a model. Overall, these parameters varied according to different vertical positions, fiber groups, teeth, and jawbones. The quantitative information of the Sharpey's fibers presented in this work facilitates our understanding of PDL functions and advances the development of biomimetic materials for periodontal tissue regeneration.

Fluoxetine effects on periodontogenesis: histomorphometrical and immunohistochemical analyses in rats

Reports have indicated that serotonin plays an important role in cell migration and differentiation during the organogenesis of several tissues, including the oral types. Administration of selective serotonin reuptake inhibitor (SSRI) drugs during pregnancy could affect the delivery of serotonin to embryonic tissues altering its development.

Immunolocalization of markers for bone formation during guided bone regeneration in osteopenic rats

Objective

The aim of this paper was to evaluate the repair of onlay autogenous bone grafts covered or not covered by an expanded polytetrafluoroethylene (e-PTFE) membrane using immunohistochemistry in rats with induced estrogen deficiency.

Material and Methods

Eighty female rats were randomly divided into two groups: ovariectomized (OVX) and with a simulation of the surgical procedure (SHAM). Each of these groups was again divided into groups with either placement of an autogenous bone graft alone (BG) or an autogenous bone graft associated with an e-PTFE membrane (BGM). Animals were euthanized on days 0, 7, 21, 45, and 60. The specimens were subjected to immunohistochemistry for bone sialoprotein (BSP), osteonectin (ONC), and osteocalcin (OCC).

Results

All groups (OVX+BG, OVX+BMG, SHAM+BG, and SHAM+BMG) showed greater bone formation, observed between 7 and 21 days, when BSP and ONC staining were more intense. At the 45-day, the bone graft showed direct bonding to the recipient bed in all specimens. The ONC and OCC showed more expressed in granulation tissue, in the membrane groups, independently of estrogen deficiency.

Conclusions

The expression of bone forming markers was not negatively influenced by estrogen deficiency. However, the markers could be influenced by the presence of the e-PTFE membrane.

An immunohistochemical study of the attachment mechanisms in different kinds of adhesive interfaces in teeth and alveolar bone of the rat

BACKGROUND AND OBJECTIVE

This study was designed to examine the histological and immunohistochemical nature of different kinds of adhesive interfaces in the rat molar region under identical experimental conditions and to discuss the structural and functional similarities between these adhesive interfaces.

MATERIAL AND METHODS

Four kinds of adhesive interfaces - an initial attachment layer for principal fibers on the developing alveolar bone surface, a reattachment layer for principal fibers on resorbed alveolar bone surface, cement lines on the alveolar bone surface unrelated to the principal fibers, and the cemento-dentinal junction - were examined in 25-d-old male Wistar rats. Routine histological staining, immunohistochemical staining for bone sialoprotein and osteopontin, and digestion tests with trypsin were conducted.

RESULTS

The adhesive interfaces showed very similar histological and immunohistochemical features: they were intensely hematoxylin-stainable, deficient in collagen fibrils, and rich in bone sialoprotein and osteopontin. After trypsin treatment the four adhesive interfaces had lost immunoreactivity to bone sialoprotein and osteopontin, and the two adjacent tissue parts held together finally separated at the adhesive interfaces.

CONCLUSION

The above findings suggest that (i) the different types of adhesive interfaces in the rat molar region have a common structure in that they are filled with highly accumulated bone sialoprotein and osteopontin and deficient in collagen fibrils; (ii) accumulated bone sialoprotein and osteopontin are closely associated with the adhesion at the interfaces; and (iii) the adhesive interfaces have a similar developmental process.