Various synthetic bone substitutes have been developed to reconstruct the bony defects that clinicians often encounter during surgical procedures. Among various synthetic bone substitutes, calcium phosphate (Ca-P) ceramics have been investigated because their composition and structure are similar to those of human bone. We evaluated the bone healing and biodegradation patterns of three types of Ca-P ceramic particle with various hydroxyapatite (HA)/β-tricalcium phosphate (β-TCP) weight ratio: pure β-TCP, biphasic Ca-P (BCP) with a HA/β-TCP weight ratio of 60/40 (BCP 60/40), and BCP with an HA/β-TCP weight ratio of 20/80 (BCP 20/80). Four 8-mm-diameter defects were created in ten rabbits. Three of the defects in each rabbit were separately and randomly filled with one of the three experimental Ca-P ceramic particles, and the fourth was filled with blood clots (control). The specimens were harvested at 2 and 8 weeks post-surgery. The histologic and histometric findings revealed that the augmented space and new bone formation were significantly better for all three Ca-P ceramics than for the control group at both 2 and 8 weeks (p < 0.05). Compared to the pure β-TCP, the two BCP groups were found to provide a larger amount of newly formed bone and bone density at the 2- and 8-week post-operative periods (p < 0.05). Throughout the observation period, BCP 60/40 and BCP 20/80 exhibited a similar bone healing and biodegradation patterns with regard to both individual particles and the total augmented area in vivo.

PurposeIn this study, we investigated the effect of silk scaffolds on one-wall periodontal intrabony defects. We conjugated nano-hydroxyapatite (nHA) onto a silk scaffold and then seeded periodontal ligament cells (PDLCs) or dental pulp cells (DPCs) onto the scaffold.MethodsFive dogs were used in this study. Bilateral 4 mm×2 mm (depth×mesiodistal width), one-wall intrabony periodontal defects were surgically created on the distal side of the mandibular second premolar and the mesial side of the mandibular fourth premolar. In each dog, four of the defects were separately and randomly assigned to the following groups: the PDLC-cultured scaffold transplantation group (PDLC group), the DPC-cultured scaffold transplantation group (DPC group), the normal saline-soaked scaffold transplantation group, and the control group. The animals were euthanized following an 8-week healing interval for clinical, scanning electron microscopy (SEM), and histologic evaluations.ResultsThere was no sign of inflammation or other clinical signs of postoperative complications. The examination of cell-seeded constructs by SEM provided visual confirmation of the favorable characteristics of nHA-coated silk scaffolds for tissue engineering. The scaffolds exhibited a firm connective porous structure in cross section, and after PDLCs and DPCs were seeded onto the scaffolds and cultured for 3 weeks, the attachment of well-spread cells and the formation of extracellular matrix (ECM) were observed. The histologic analysis revealed that a well-maintained grafted volume was present at all experimental sites for 8 weeks. Small amounts of inflammatory cells were seen within the scaffolds. The PDLC and DPC groups did not have remarkably different histologic appearances.ConclusionsThese observations indicate that nHA-coated silk scaffolds can be considered to be potentially useful biomaterials for periodontal regeneration.

BackgroundThe aim of this study was to characterize the efficacy of nano-hydroxyapatite-coated silk fibroin constructs as a scaffold for bone tissue engineering and to determine the osteogenic effect of human dental pulp and periodontal ligament derived cells at an early stage of healing in rabbits. 3D silk fibroin constructs were developed and coated using nano-hydroxyapatite crystals. Dental pulp and periodontal ligament cells from extracted human third molars were cultured and seeded onto the silk scaffolds prior to in vivo implantation into 8 male New Zealand White rabbits. Four circular windows 8 mm in diameter were created in the calvarium of each animal. The defects were randomly allocated to the groups; (1) silk scaffold with dental pulp cells (DPSS), (2) silk scaffold with PDL cells (PDLSS), (3) normal saline-soaked silk scaffold (SS), and (4) empty control. The animals were sacrificed 2 (n = 4) or 4 weeks (n = 4) postoperatively. The characteristics of the silk scaffolds before and after cell seeding were analyzed using SEM. Samples were collected for histologic and histomorphometic analysis. ANOVA was used for statistical analysis.ResultHistologic view of the experimental sites showed well-maintained structure of the silk scaffolds mostly unresorbed at 4 weeks. The SEM observations after cell-seeding revealed attachment of the cells onto silk fibroin with production of extracellular matrix. New bone formation was observed in the 4 week groups occurring from the periphery of the defects and the silk fibers were closely integrated with the new bone. There was no significant difference in the amount of bone formation between the SS group and the DPSS and PDLSS groups.ConclusionWithin the limitations of this study, silk scaffold is a biocompatible material with potential expediency as an osteoconductive scaffold in bone tissue engineering. However, there was no evidence to suggest that the addition of hDPCs and hPDLCs to the current rabbit calvarial defect model can produce an early effect in augmenting osteogenesis.

It can be conjectured that preservation of buccal plate by using the TM in immediate implantation was not predictable due to vulnerability to wound dehiscence and substantial pseudoperiosteum formation beneath the TM.

PurposeRecent interest has focused on intentional replantation to restore an original tooth. Some studies have shown successful results with intentional replantation for periodontally involved teeth. For long-term success of replantation, a healthy periodontal status of the recipient site is required so that delayed replantation is more suitable for periodontally involved teeth. To reveal the ideal timing for delayed replantation of periodontally involved teeth, the healing process of extraction sockets after extraction of periodontitis-induced teeth in rats was evaluated.MethodsTwenty-eight rats were randomly divided into two groups: a control group (n=8) and test group (n=20). In the test group, periodontitis was induced by a ligature around the cervix of the mandibular first molar of all of the rats. Two weeks later, the mandibular first molars were extracted in all of the animals. The animals were sacrificed on days 0, 3, 7, and 10 after extraction and histological and immunohistochemical analysis was performed.ResultsIn histological analysis of the test group, inflammatory cell infiltrate was found abundantly in the remaining periodontium 3 days after tooth extraction and decreased gradually at later time points. In immunohistochemical analysis of the test group, both interleukin-6 (IL-6) and, tumor necrosis factor-α (TNF-α) were numerous in the furcation area at each postextraction day. IL-6 was stained more heavily between 3 and 7 days after extraction; at day 10 after extraction, little staining was observed. TNF-α staining was more intense at 3 days after extraction and gradually weakened at later points in time.ConclusionsWithin the limits of this study, it takes at least 10 days to resolve periodontal inflammation in rat extraction sockets.