Search

We succeeded in the electrical polarization of β-tricalcium phosphate (β-TCP) granules and performed an unprecedented attempt to implant them into maxillary bone defects in canines to confirm their ability to facilitate new bone formation. Two holes were drilled into each maxilla half of a canine and filled with electrically polarized and nonpolarized β-TCP granules (grouping assignment was decided randomly). The implanted specimens were dissected en bloc and used for microcomputed tomography (μCT) observations and histological analyses 4 and 8 weeks after the operation. New bone ingrowth in the bone hole progressed over time from the superficial layer of the cortex toward the inner cancellous bone. The percentage area of new bone in the bone hole, as measured by μCT in the sagittal plane, was significantly larger after 4 and 8 weeks, and that measured by H&E-stained specimens in the transverse plane after 4 weeks was significantly larger in the polarized group than in the nonpolarized group. In addition to the structural stability and chemical characteristics of the β-TCP granules, electrical stimulation bears influence not indirectly but directly on osteogenic and vessel cells, which might work cooperatively for the early initiation of the bone formation process.

Objective The present study aimed to evaluate the histological outcome of tunnel β-TCP blocks grafting in extraction sockets missing the buccal bone wall, after 6 months of healing. Background Tunnel β-tricalcium phosphate (β-TCP) blocks made of randomly organized tunnel-shaped β-TCP ceramics appeared promising for alveolar ridge preservation in tooth extraction sockets missing the buccal bone, in a previous study in dogs, with a 2-month healing time. Methods In six beagle dogs, the maxillary first premolars were extracted and the buccal bone was surgically removed to create bone defects of 4 mm (mesio-distal) × 5 mm (apico-coronal) × 4 mm (bucco-palatal). Thus, extraction sockets missing the buccal bone plate were grated with tunnel β-TCP blocks (test) or left empty for spontaneous healing (control). Histology/histomorphometry was performed after 6 months of healing. Results The horizontal bucco-palatal width of the alveolar ridge was significantly greater at test sites than at control sites. The amount of mineralized tissue was greater at test sites (57.8% ± 11.1%) than at control sites (28.9% ± 8.5%), while the amount of connective tissue was significantly greater at control sites (41.7% ± 6.4%) than at test sites (19.6% ± 9.2%). No significant difference was found between sites in terms of basic multicellular units and bone marrow. Residual β-TCP at test sites was 5.8% ± 3.2%. Conclusion Grafting with tunnel β-TCP block significantly limited the resorption of the alveolar ridge at extraction sockets missing the buccal bone compared with sites left to heal spontaneously, even after 6-month follow-up.

Background The alveolar ridge undergoes pronounced reduction in height and width following tooth extraction. This study aims to comparatively evaluate the potential for ridge preservation in extraction sockets with buccal bone deficiency of β-tricalcium phosphate coated with poly lactide-co-glycolide (β-TCP/PLGA) and conventional particulate β-TCP. Methods In six beagles, maxillary first premolars were extracted after removal of their buccal bone plates. Standardized bone defects (4 [mesiodistal width] × 4 [buccopalatal width] × 5 [depth] mm) were created at the sites of extraction sockets and filled with β-TCP/PLGA (test sites) or particulate β-TCP (control sites). Microcomputed tomography, histologic, and histometric evaluations were performed 12 weeks post-surgery. Results The test sites exhibited a significantly greater bone volume than the control sites (25.7 ± 2.14 versus 16.0 ± 3.3 mm3 ), although no statistically significant difference was detected in bone material density (746.3 ± 23.9 versus 714.5 ± 37.0 g/cm3 , respectively). Relative to the control sites, the test sites exhibited significantly greater alveolar-ridge coronal (2.0 ± 0.4 versus 1.1 ± 0.3 mm) and middle (2.9 ± 0.2 versus 2.1 ± 0.3 mm) horizontal widths and proportions of woven bone (50.3 ± 8.1% versus 38.0 ± 5.2%) and bone marrow (17.7 ± 6.6% versus 9.7 ± 4.1%) but a significantly lower proportion of connective tissue (10.7 ± 4.5% versus 18.3 ± 5.7%). Conclusion Within the limitations of this study, the moldable β-TCP/PLGA graft appears to exhibit a greater potential than the conventional particulate β-TCP graft for ridge preservation of extraction sockets with buccal bone deficiency.

Background and objective It is well known that recombinant human fibroblast growth factor-2 (rhFGF-2) signaling plays an important role in tissue repair and regeneration. rhFGF-2 strongly binds to acidic gelatin via ionic linkages and is gradually released upon gelatin decomposition. On the other hand, the linkage between rhFGF-2 and basic gelatin is so weak that most rhFGF-2 is rapidly released from basic gelatin by simple desorption. Gelatin/β-tricalcium phosphate (β-TCP) sponges, which comprise 50 wt% gelatin and 50 wt% β-TCP in a cross-linked structure, can release rhFGF-2 gradually owing to their electrical features. In a previous study, we reported that new bone height in the test group using rhFGF-2 with acidic gelatin/β-TCP sponges was significantly greater than that in the control group using acidic gelatin/β-TCP sponges alone in a ridge augmentation model in dogs. However, whether these results depend on controlled release by the gelatin/β-TCP sponges remains controversial. In this study, we evaluated the effects of controlled release by comparing acidic and basic gelatin/β-TCP sponges with different isoelectric points (IEP) on ridge augmentation in dogs. Materials and methods Twelve weeks after extraction of the maxillary second and third incisors of six dogs, critically sized saddle-type defects (8 mm length × 4 mm depth) were surgically created bilaterally 2 mm from the mesial side of the canine. Acidic gelatin/β-TCP sponges (IEP 5.0) soaked with 0.3% rhFGF-2 were applied to the defect in the acidic group, whereas basic gelatin/β-TCP sponges (IEP 9.0) soaked with 0.3% rhFGF-2 were applied to the defect in the basic group. Twelve weeks after surgery, biopsy specimens were obtained and subjected to microcomputed tomography (micro-CT) and histological analyses. Results New bone area detected by micro-CT analysis was significantly smaller in the basic group than in the acidic group. New bone height calculated by histologic sections was significantly lower in the basic group than in the acidic group. The total tissue height was lower in the basic group than in the acidic group. However, the differences between both sites were not significant. Conclusions These findings suggest that in ridge augmentation of saddle-type defects, controlled release of rhFGF-2 induces notably more alveolar bone formation than does short-term application of rhFGF-2.

OBJECTIVES This study aimed to evaluate the plaque removal efficacy of a newly developed electric-powered ionic toothbrush vs. a manual toothbrush. MATERIALS AND METHODS Manual or electric-powered ionic toothbrushes were randomly assigned to 30 healthy volunteers divided into two groups (Phase I). After 2 min of brushing, all tooth surfaces were stained with a plaque staining solution, and blinded examiners performed scoring using the Rustogi Modification of the Navy Plaque Index. Plaque removal rate was calculated at the central incisors, first premolar and first molar, as representative teeth, in the maxilla and mandibula. One week following Phase I, the same examinations were repeated in all subjects using another toothbrush (Phase II), as a crossover design. RESULTS Electric ionic toothbrushes demonstrated a significantly higher plaque removal rate than manual toothbrushes in the premolar and molar areas (p

This study evaluated the effectiveness of swept-source optical coherence tomography (ss-OCT) for detecting calculus and root cementum during periodontal therapy. Optical coherence tomography (OCT) images were taken before and after removal of subgingival calculus from extracted teeth and compared with non-decalcified histological sections. Porcine gingival sheets of various thicknesses were applied to the root surfaces of extracted teeth with calculus and OCT images were taken. OCT images were also taken before and after scaling and root planing (SRP) in human patients. In vitro, calculus was clearly detected as a white-gray amorphous structure on the root surface, which disappeared after removal. Cementum was identified as a thin, dark-gray layer. The calculus could not be clearly observed when soft tissues were present on the root surface. Clinically, supragingival calculus and cementum could be detected clearly with OCT, and subgingival calculus in the buccal cervical area of the anterior and premolar teeth was identified, which disappeared after SRP. Digital processing of the original OCT images was useful for clarifying the calculus. In conclusion, ss-OCT showed potential as a periodontal diagnostic tool for detecting cementum and subgingival calculus, although the practical applications of subgingival imaging remain limited.

Background and Objective Tissue engineering by using recombinant human (rh) growth factor technology may offer a promising therapeutic approach for treatment of gingival recession. Fibroblast growth factor-2 (FGF-2) has shown the ability to promote periodontal regeneration. Gelatin/beta-tricalcium phosphate (gelatin/β-TCP) sponges have been developed to control the release of growth factors. The present study evaluated the periodontal regenerative efficacy of rhFGF-2 by comparing gelatin/β-TCP sponges incorporated with rhFGF-2 to the scaffolds alone in artificially created recession-type defects in dogs. Material and methods Critically sized buccal gingival recession defects were surgically created on maxillary canine teeth of five dogs. In each animal, defects were randomized to receive either a gelatin/β-TCP sponge soaked with rhFGF-2 (gelatin/β-TCP/rhFGF-2) or phosphate-buffered saline (gelatin/β-TCP). Eight weeks after surgery, biopsy specimens were obtained and subjected to microcomputed tomography and histological analyses. Results Complete root coverage was achieved in both groups. Microcomputed tomography revealed significantly greater new bone volume in the gelatin/β-TCP/rhFGF-2 group. Histologically, both groups achieved periodontal regeneration; however, gelatin/β-TCP/rhFGF-2 sites exhibited more tissue regeneration, characterized by significantly larger amounts of new cementum and new bone. Gelatin/β-TCP sites featured increased long junctional epithelium and connective tissue attachment. In the gelatin/β-TCP/rhFGF-2 sites, new bone exhibited many haversian canals and circumferential lamellae as well as remarkably thick periosteum with blood vascularization and hypercellularity. Conclusion Within the limitations of this study, rhFGF-2 in gelatin/β-TCP sponges exhibits an increased potential to support periodontal wound healing/regeneration in canine recession-type defects.

Reduction in alveolar ridge volume is a direct consequence of tooth extraction. Tunnel β-tricalcium phosphate (β-TCP) blocks were manufactured from randomly organized tunnel-shaped β-TCP ceramic. Efficacy of these blocks compared to extraction alone for alveolar ridge preservation after tooth extraction with buccal bone deficiency was evaluated.Maxillary first premolars of six beagle dogs were extracted after removing the buccal bone, and bone defects of 4 × 4 × 5 mm (mesio-distal width × bucco-palatal width × depth) were created. Fresh extraction sockets with buccal bone defects were filled with tunnel β-TCP blocks at test sites. Two months after the operation, histologic and histometric evaluations were performed.Regarding histologic sections, coronal and middle horizontal widths of the alveolar ridge were significantly greater at test sites (3.2 ± 0.5 and 3.6 ± 0.4 mm, respectively) than at control sites (1.2 ± 0.3 and 2.0 ± 0.6 mm, respectively). The amount of woven bone was significantly greater at test sites (62.4% ± 7.9%) than at control sites (26.8% ± 5.3%), although that of connective tissue and bone marrow was significantly greater at control sites (38.1% ± 6.2% and 16.0% ± 6.9%, respectively) than at test sites (10.7% ± 5.7% and 4.1% ± 2.2%, respectively). Regarding basic multicellular units, no statistically significant difference was found between the test and control sites (0.5% ± 0.1% and 0.6% ± 0.1%, respectively).Tunnel β-TCP blocks represent an effective bone-graft material for alveolar ridge preservation in fresh extraction sockets with buccal bone defects.

The histological outcomes after nonsurgical periodontal treatment with enamel matrix derivatives (EMD) remain controversial. The present study evaluated periodontal wound healing after scaling and root planing (SRP) with subgingival application of EMD for treatment of experimental periodontitis. Periodontal breakdown was induced by applying silk ligatures around mandibular third and fourth premolars of six beagle dogs until radiographic bone loss progressed to approximately half of the root length. Probing pocket depth (PPD) and clinical attachment level (CAL) were proximally measured 2 weeks after ligature removal (baseline). Mesial and distal surfaces of the experimental teeth were subjected to SRP and randomized using a split-mouth design to subgingival application of EMD (test) or normal saline (control). PPD and CAL were re-evaluated at 11 weeks. Animals were sacrificed at 12 weeks for histological analyses. No significant differences were observed in PPD and CAL between both groups at baseline and at 11 weeks. Histologically, test sites exhibited a greater amount of new cementum than that did the control sites (p

Background and Objective Tissue regeneration is affected by the porosity, chemical properties and geometric structure of graft materials. Regeneration of severe periodontal defects, such as one-wall intrabony defects, is difficult because of reduced tissue support, and bone grafts are commonly used in such cases. In the present study, a tunnel-structured β-tricalcium phosphate (tunnel β-TCP) graft material designed to stimulate bone formation was fabricated. The objective of this pilot study was to evaluate the effect of this graft material on periodontal regeneration in one-wall intrabony defects in dogs. Material and Methods Six male beagle dogs were used in this study. First, the mandibular second and third incisors were extracted. Experimental surgery was performed 12 wk after tooth extraction. Bilateral 4 × 8 mm (width × depth) one-wall intrabony defects were created in the mesial side of the mandibular canines. At the experimental sites, the defects were filled with tunnel β-TCP, whereas the control defects were left empty. Twelve weeks after surgery, qualitative and quantitative histological analyses were performed. Results There were no signs of clinical inflammation 12 wk after surgery. Coronal extension indicative of new bone formation was higher at the experimental sites than at the control sites, although the differences between both the sites in the newly formed cementum and connective tissue attachment were not significant. Newly formed periodontal ligament and cementum-like tissue were evident along the root surface at the experimental sites. The inner surface of the tunnels was partially resorbed and replaced with new bone. New blood vessels were observed inside the lumens of tunnel β-TCP. Conclusion Tunnel β-TCP serves as a scaffold for new bone formation in one-wall intrabony defects.

High-mobility group box-1 (HMGB1) protein acts as a transcription factor in the nucleus and also as a pro-inflammatory cytokine when released into extracellular fluids. The presence of higher levels of HMGB1 is reported in the gingival crevicular fluid from periodontal patients. Since the proliferation of bacteria within the periodontal pocket is closely involved in the exacerbation of periodontal disease, it is hypothesized that the periodontal pocket causes the release of HMGB1. Immunohistochemical staining of inflamed gingiva revealed that HMGB1 is exclusively dislocated from the nucleus to the cytoplasm in the pocket epithelium, whereas it is mainly present in the nucleus in the gingival epithelium. Butyric acid, an extracellular metabolite from periodontopathic bacteria populating the periodontal pocket, induced the passive release of HMGB1 as a result of eliciting necrosis in the human gingival epithelial cell line. Thus, the periodontal epithelium may provide a unique pathological setting for HMGB1 release by bacterial insult. Abbreviations: HMGB1, high-mobility group box-1; TNF-α, tumor necrosis factor-α; CHX, cycloheximide; PI, propidium iodide; ROS, reactive oxygen species; HDAC, histone deacetylase.

Background and Objective Fibroblast growth factor-2 (FGF-2) regulates the proliferation and differentiation of osteogenic cells, resulting in the promotion of bone formation. Biodegradable gelatin sponges incorporating β-tricalcium phosphate (β-TCP) have been reported as a scaffold, which has the ability to control growth factor release, offering sufficient mechanical strength and efficient migration of mesenchymal cells. In this study, we evaluated the effects of the combined use of recombinant human FGF-2 (rhFGF-2) and gelatin/β-TCP sponge on ridge augmentation in dogs. Material and Methods Six male beagle dogs were used in this study. Twelve wk after tooth extraction, bilateral 10 × 5 mm (width × depth) saddle-type defects were created 3 mm apart from the mesial side of the maxillary canine. At the experimental sites, the defects were filled with gelatin/β-TCP sponge infiltrated with 0.3% rhFGF-2, whereas gelatin/β-TCP sponge infiltrated with saline was applied to the control sites. Eight wk after surgery, qualitative and quantitative analyses were performed. Results There were no signs of clinical inflammation at 8 wk after surgery. Histometric measurements revealed that new bone height at the experimental sites (2.98 ± 0.65 mm) was significantly greater than that at the control sites (1.56 ± 0.66 mm; p = 0.004). The total tissue height was greater at the experimental sites (6.62 ± 0.66 mm) than that at the control sites (5.95 ± 0.74 mm), although there was no statistical significant difference (p = 0.051). Cast model measurements revealed that the residual defect height at the experimental sites (2.31 ± 0.50 mm) was significantly smaller than that at the control sites (3.51 ± 0.78 mm; p = 0.012). Conclusion The combined use of rhFGF-2 and gelatin/β-TCP sponge promotes ridge augmentation in canine saddle-type bone defects.

Objective: The ultimate goal of periodontal treatment is to regenerate the damaged periodontal support. Although periodontal ligament (PDL) cells are essential for periodontal regeneration, few studies have reported the transplantation of periodontal ligament cells to periodontal defects. We developed a new method to apply periodontal ligament cells as a sheet to the defect. The aim of this study was to investigate the periodontal healing after application of the periodontal ligament cell sheet in beagle dogs. Methods: Autologous periodontal ligament cells were obtained from extracted premolars of each beagle dog. Periodontal ligament cell sheets were fabricated using a temperature-responsive cell culture dish. Dehiscence defects were surgically created on the buccal surface of the mesial roots of bilateral mandibular first molars of each dog. In the experimental group (five defects), periodontal ligament cell sheet with reinforced hyaluronic acid carrier was applied to the defect. Only the hyaluronic acid carrier was applied to the contralateral side as a control (five defects). Eight weeks after surgery, the animals were sacrificed and decalcified specimens were prepared. Healing of the periodontal defects was evaluated histologically and histometrically. Results: No clinical signs of inflammation or recession of gingiva were observed in both experimental and control groups. In the experimental group, periodontal tissue healing with bone, periodontal ligament and cementum formation was observed in three out of five defects. In the control group, such periodontal tissue formation was not observed except in one defect. Histometric analysis revealed that the formation of new cementum in the experimental group was significantly higher than that in the control group. Conclusion: The periodontal ligament cell sheet has a potential to regenerate periodontal tissue and may become a novel regenerative therapy.