Ectopic Bone Induction by BMP-loaded Collagen Scaffold and Bone Marrow Stromal Cell Sheet

We combined the use of bone morphogenetic protein-2(BMP-2)-loaded collagen scaffold and cultured bone marrow stromal cell (BMSC) sheet in order for developing new bone tissue engineering.Rat BMSC sheets were generated in the presence of dexamethasone, β-glycerophosphate and ascorbic acid. Four types of the grafts were implanted in the intermuscular region of rat femurs: control group, collagen sponge; cell group, BMSC sheet in collagen sponge; BMP group, BMP-2-loaded collagen sponge; and BMP-cell group, BMSC sheet in BMP-2-loaded collagen sponge. Four weeks after surgery, histological and histomorphometric analysis were performed.The BMP-cell group demonstrated abundant new bone formation compared to all the other groups (p<0.05) and marked resorption of the implanted collagen when compared to the control and cell groups (p<0.05).The combination of BMP-2-loaded collagen sponge and BMSC sheet appeared to successfully promote an osteoinduction

Bone Augmentation by Implantation of an FGF2-loaded Collagen Gel-sponge Composite Scaffold

Fibroblast growth factor-2 (FGF2) plays a critical role in osteoblastic cell proliferation. Collagen gel-sponge composite is an effective scaffold for tissue engineering. The purpose of this study was to evaluate whether addition of FGF2 to collagen gel-sponge composite promotes bone augmentation in rats.The rats were assigned to groups designated F0, F3 and F15, and received implantation of collagen gel-sponge composite containing 0, 3 and 15 µg FGF2, respectively, into a cranial bone defect. Specimens were prepared 1, 2 and 5 weeks after surgery for histologic and histomorphometric analysis.Newly formed bone area in groups F3 and F15 was significantly greater than that in group F0 at all stages. These results suggest that FGF2-loaded collagen gel-sponge composite scaffold stimulates bone augmentation and might provide a more effective bone engineering approach

The effects of collagen hydrogel implantation in buccal dehiscence defects in beagles.

Type I collagen hydrogel treated by an ascorbate-copper ion crosslinking system is highly biocompatible and highly degradable in the body. The purpose of this study was to examine the effect of collagen hydrogel on periodontal wound healing in beagles. Sixty-four periodontal dehiscence type defects were created on the buccal roots of four beagles. Subsequently, collagen hydrogel was implanted in each defect in the experimental group and sutured, and, in the control group, the defect was sutured without any application of collagen hydrogel. The percentage of the length of new bone and new cementum in the experimental group was significantly greater than that in the control group at weeks 4 (p<0.01) and 8 (p<0.05). Significantly more junctional epithelium was observed in the control group than in the experimental group at weeks 2 (p<0.01) and 4 (p<0.05). These findings thus indicate that periodontal regeneration was stimulated by collagen hydrogel implantation in beagles

Application of collagen hydrogel/sponge scaffold facilitates periodontal wound healing in class II furcation defects in beagle dogs

Background and Objective:  A three-dimensional scaffold may play an important role in periodontal tissue engineering. We prepared bio-safe collagen hydrogel, which exhibits properties similar to those of native extracellular matrix. The aim of this study was to examine the effect of implantation of collagen hydrogel/sponge scaffold on periodontal wound healing in class II furcation defects in dogs. Material and Methods:  The collagen hydrogel/sponge scaffold was prepared by injecting collagen hydrogel, cross-linked to the ascorbate-copper ion system, into a collagen sponge. Class II furcation defects (of 5 mm depth and 3 mm width) were surgically created in beagle dogs. The exposed root surface was planed and demineralized with EDTA. In the experimental group, the defect was filled with collagen hydrogel/sponge scaffold. In the control group, no implantation was performed. Histometric parameters were evaluated 2 and 4 wk after surgery. Results:  At 2 wk, the collagen hydrogel/sponge scaffold displayed high biocompatibility and biodegradability with numerous cells infiltrating the scaffold. In the experimental group, reconstruction of alveolar bone and cementum was frequently observed 4 wk after surgery. Periodontal ligament tissue was also re-established between alveolar bone and cementum. Volumes of new bone, new cementum and new periodontal ligament were significantly greater in the experimental group than in the control group. In addition, epithelial down-growth was suppressed by application of collagen hydrogel. Conclusion:  The collagen hydrogel/sponge scaffold possessed high tissue compatibility and degradability. Implantation of the scaffold facilitated periodontal wound healing in class II furcation defects in beagle dogs

Periodontal tissue repair after sealing of the gap in vertical root fracture

The aim of this study was to determine whether sealing of fracture gap using adhesive resin through the root canal can prevent inflammation of periodontal tissue, and resealing the incompletely sealed fracture gap from outside can resolve such inflammation in experimentally created vertical root fractures. Vertical root fractures were created in incisor of beagles. In the experimental group, the fracture gap was sealed through the root canal with adhesive resin. After 5 weeks, sites with the clinical attachment level >= 4 mm were further divided randomly into the poor-replanting group and the poor-untreated group. In the poor-replanting group, the tooth was extracted and replanted after resealing the fracture gap with adhesive resin from the outer surface. Sites with clinical attachment level <= 3 mm after 5 weeks were considered as the satisfactory group. The poor-untreated group and the satisfactory group were subjected to no further treatment. The clinical attachment level was evaluated at baseline and after 2, 5, and 9 weeks. After 9 weeks, histological measurements were made to determine the length of the epithelial downgrowth and the area of alveolar bone resorption. The clinical attachment level and the area of bone resorption were significantly smaller in the poor-replanting group and the satisfactory group than in the poor-untreated group (p < 0.05). The results indicate the possibility that periodontal inflammation along the fracture line can be prevented and improved if the fracture gap is sealed

Influence of Root Dentin Surface Conditioning with Bone Morphogenetic Protein-2 on Periodontal Wound Healing in Beagle Dogs

Bone morphogenetic protein-2 (BMP-2) may play a major role in osteoinduction and osteoclast differentiation. The influence of BMP-2 conditioning in graded doses to root dentin surface on periodontal wound healing was examined.Twenty-four periodontal defects were surgically created on the buccal roots of four beagle dogs. The denuded root dentin surfaces were demineralized with 24% EDTA, 0.1 and 1.0 μg/μL BMP-2 solution (15 μL) was applied, and the groups were labeled as low-dose BMP (BL) and high-dose BMP (BH), respectively. In the control roots, phosphate-buffered saline was applied to the root surface. Specimens were histologically analyzed 16 weeks after surgery.Periodontal wound healing was stimulated by conditioning with BMP-2. Formation of alveolar bone and cementum-like tissue was observed; however, in BH group, ankylosis and root resorption were accelerated in the defect area, and there was little evidence of periodontal ligament formation between alveolar bone and root surface

Root surface conditioning with bone morphogenetic protein-2 facilitates cementum-like tissue deposition in beagle dogs

Background and objective: Modification of the root surface may play an important role in regenerating the periodontal attachment between the root and periodontal connective tissue. We speculated that bone morphogenetic protein (BMP) application to root surface resulted in a novel attachment by cementum-like hard tissue, although non-osteogenic tissue proliferated to the root surface. The aim of this study was to examine whether BMP-2 guided cementum-like tissue deposition on a BMP-conditioned root surface. Material and Methods: Root dentin on the buccal side of 24 teeth in four beagle dogs was surgically exposed. The denuded root dentin surfaces were demineralized with EDTA and washed with saline. Subsequently, 15 μl of BMP-2 solution (loading dose; 0.4 and 1.0 μg/μl) was applied to the root dentin surface. In the control, phosphate-buffered saline was applied to the root surface. Specimens were histologically analyzed 16 weeks after surgery. Results: Formation of cementum-like tissue was frequently observed on the BMP-2-conditioned root at the coronal portion. Cellular cementum-like tissue was separated from the original cementum and encapsulated with gingival connective tissue. Cementum-like tissue formation with BMP at 1.0 μg/μl was significantly greater than those in the control and BMP at 0.4 μg/μl. Downgrowth of the junctional epithelium in the 1.0 μg/μl BMP group was significantly less than that in the control. Conclusions: Root dentin surface conditioning with BMP-2 stimulated cementum-like tissue formation and inhibited epithelial downgrowth

Haemodynamic reactions in human masseter muscle during different types of contractions

Objectives : To investigate to what extent different types of jaw-muscle contractions cause haemodynamic reactions in human masseter muscle. Materials and Methods : Eleven healthy volunteers (seven males : 25.0±2.9 years and four females: 23.3±4.3 years) performed three standardized oral-motor tasks : maximal voluntary contractions (MVC ; duration 5 sec, 3 times repetition), tooth grinding (repetitive left and right side grinding from intercuspal position to canine-to-canine position at 0.5 Hz keeping 50% MVC for a total of 10 times), and 1-min left-side gum chewing at 1 Hz. Haemodynamic characteristics were measured in the left masseter muscle with the use of a laser blood oxygenation monitor (BOML1TRW, OMEGAWAVE INC., Tokyo, Japan). Electromyographic (EMG) activity from right and left masseter muscle was simultaneously monitored (500 Hz sample frequency) during the tasks. 1-ANOVA followed by Dunnett’s test was used. Results : Oxygenated haemoglobin (OXYHb : 13.5±0.2 104 units/mm3) and deoxygenated haemoglobin (deOXYHb : 7.6 ± 0.3 104 units/mm3) did not change significantly during the MVC task (13.9±0.2 and 7.8±0.3 104 units/mm3, respectively, P>0.065), however, the total haemoglobin (TOTALHb : 22.1±0.3 104 units/mm3) showed a significant increase (22.7±0.3 104 units/mm3, P=0.003) during the MVC. Tissue blood oxygen saturation was not changed during the MVC (P=0.164). During the tooth grinding task, OXYHb, deOXYHb, TOTALHb, and tissue blood oxygen saturation (StO2) remained constant (P>0.127). Finally, the chewing task was associated with significant decreases in StO2 (67.9±0.7%, P=0.006) related to a decrease in OXYHb (14.0±0.2 104 units/mm3, P=0.040) compared to baseline (68.8±0.7% and 14.2 ±0.3 104 units/mm3, respectively). Conclusion : These results showed that high-intensity experimental tooth clenching caused constriction-like reactions in the masseter muscle whereas tooth grinding did not cause detectable changes in haemodynamic characteristics of masseter muscle. Finally, the findings indicated that rhythmic dynamic contractions might lead to oxygen deficit in the masseter muscle. The present data may have implications for understanding the potential pathophysiological consequences of different types of oral-motor tasks, e.g., bruxism and prolonged mastication