Periodontal regenerative effect of a bovine hydroxyapatite/collagen block in one-wall intrabony defects in dogs: a histometric analysis

Bioceramic scaffolds with two-step internal/external modification of copper-containing polydopamine enhance antibacterial and alveolar bone regeneration capability

Magnesium-doped calcium silicate (CS) bioceramic scaffolds have unique advantages in mandibular defect repair; however, they lack antibacterial properties to cope with the complex oral microbiome. Herein, for the first time, the CS scaffold was functionally modified with a novel copper-containing polydopamine (PDA(Cu2+‍)) rapid deposition method, to construct internally modified (*P), externally modified (@PDA), and dually modified (*P@PDA) scaffolds. The morphology, degradation behavior, and mechanical properties of the obtained scaffolds were evaluated in vitro. The results showed that the CS*P@PDA had a unique micro-/nano-structural surface and appreciable mechanical resistance. During the prolonged immersion stage, the release of copper ions from the CS*P@PDA scaffolds was rapid in the early stage and exhibited long-term sustained release. The in vitro evaluation revealed that the release behavior of copper ions ascribed an excellent antibacterial effect to the CS*P@PDA, while the scaffolds retained good cytocompatibility with improved osteogenesis and angiogenesis effects. Finally, the PDA(Cu2+)-modified scaffolds showed effective early bone regeneration in a critical-size rabbit mandibular defect model. Overall, it was indicated that considerable antibacterial property along with the enhancement of alveolar bone regeneration can be imparted to the scaffold by the two-step PDA(Cu2+) modification, and the convenience and wide applicability of this technique make it a promising strategy to avoid bacterial infections on implants.

A Review of Tissue Engineering for Periodontal Tissue Regeneration

Periodontal disease is one of the most common diagnoses in small animal veterinary medicine. This infectious disease of the periodontium is characterized by the inflammation and destruction of the supporting structures of teeth, including periodontal ligament, cementum, and alveolar bone. Traditional periodontal repair techniques make use of open flap debridement, application of graft materials, and membranes to prevent epithelial downgrowth and formation of a long junctional epithelium, which inhibits regeneration and true healing. These techniques have variable efficacy and are made more challenging in veterinary patients due to the cost of treatment for clients, need for anesthesia for surgery and reevaluation, and difficulty in performing necessary diligent home care to maintain oral health. Tissue engineering focuses on methods to regenerate the periodontal apparatus and not simply to repair the tissue, with the possibility of restoring normal physiological functions and health to a previously diseased site. This paper examines tissue engineering applications in periodontal disease by discussing experimental studies that focus on dogs and other animal species where it could potentially be applied in veterinary medicine. The main areas of focus of tissue engineering are discussed, including scaffolds, signaling molecules, stem cells, and gene therapy. To date, although outcomes can still be unpredictable, tissue engineering has been proven to successfully regenerate lost periodontal tissues and this new possibility for treating veterinary patients is discussed.

Bone regeneration is enhanced by the combined use of acid-electrolyzed functional water with hydroxyapatite/collagen composite

Hydroxyapatite/collagen (HAP/Col) composite has a nanostructure and composition similar to that of natural bone. Herein, we have evaluated the beneficial effects of acid-electrolyzed functional water (FW) in combination with HAP/Col composite as an irrigation material in a rat calvarium defect model. The rats were divided into four groups: control, PBS irrigation; FW, FW irrigation; HAP/Col, filled with HAP/Col; FW + HAP/Col, FW irrigation prior to HAP/Col filling. Bone volume (BV) and bone mineral density (BMD) of the newly formed bone were analyzed by microcomputed tomography. The results indicated that the combined use of FW and HAP/Col significantly augmented both BV (12.25 ± 1.93 mm³ , control: 3.22 ± 0.55 mm³ , 6 weeks) and BMD (120.09 ± 14.76 cm³ /mg vs. control: 54.67 ± 7.20 cm³ /mg, 6 weeks) in a time-dependent manner, which might be attributed to the soluble factor-inducing ability of FW. Based on this assumption, bFGF concentration in peripheral blood was measured. bFGF concentration was significantly increased in the FW + HAP/Col group (68.25 ± 9.2 pg/ml vs. control: 21.70 ± 8.18 pg/ml, 6 hr). Real-time PCR demonstrated significant augmentation of MCSF (2.82 ± 0.59-fold), RANKL (2.51 ± 0.33-fold) and BMP7 (1.66 ± 0.25-fold) (bone regeneration-related genes) and PDGF (1.31 ± 0.15-fold), VEGF (3.27 ± 0.42-ld) and IL-8 (6.77 ± 2.02-fold) (angiogenic genes) mRNAs in the FW + HAP/Col group. Taken together, these results suggest that the combined use of FW and HAP/Col induces bone regeneration, presumably by inducing the factors contributing to bone regeneration and angiogenesis.

Evaluation of Porcine Hybrid Bone Block for Bone Grafting in Dentistry

BACKGROUND/AIM

The purpose of this study was to develop hybrid bone blocks using porcine-derived collagen and low crystalline porcine-derived hydroxyapatite to overcome the disadvantages of commonly used bone grafts in dentistry.

MATERIALS AND METHODS

Collagen was added to hydroxyapatite particles to increase the spatial integration of particulate bone grafts. Physicochemical examination and in vivo tests were performed to analyze scaffold's characteristics and evaluate bone regeneration.

RESULTS

Porcine hybrid bone block had an irregular and interconnecting macroporous structure that was adequate for bone regeneration and bone ingrowth, and showed a good space-occupying ability to become well positioned. In addition, it showed higher angiogenesis and biodegradability than Bio-Oss Collagen®, a commercialized bone graft used in dental clinics.

CONCLUSION

Our results suggest that improved collagen hybrid bone block can be generated when porcine cancellous bone particles and collagen were reasonably mixed. This hybrid bone block was easy in handling had flexibility, good biodegradability and provided bone regeneration.

Bone Regeneration of Peri-Implant Defects Using a Collagen Membrane as a Carrier for Recombinant Human Bone Morphogenetic Protein-2

This study is designed to determine the effect of collagen membrane (CM) soaked with bone morphogenetic protein-2 (rhBMP-2) for the treatment of peri-implant dehiscence defects. Material and Methods. Three treatment groups were allocated at each defect in 5 dogs: (i) collagenated synthetic bone (OC) and CM soaked with rhBMP-2 (BMP group), (ii) OC and CM soaked with saline (nonBMP group), and (iii) no further treatment (control group). Titanium pins were used to stabilize the membranes in two dogs. Radiographic and histomorphometric analyses were performed 4 weeks later. Results. The median augmented volumes were 4.27 mm³, 6.24 mm³, and 2.75 mm³ in the BMP, nonBMP, and control groups, respectively; the corresponding median first bone-to-implant contact (fBIC) distances were 3.25 mm, 3.08 mm, and 2.56 mm (P > 0.05). The placement of pins (with the BMP and nonBMP groups pooled) significantly improved bone regeneration: the augmented volumes were 17.60 mm³ with pins and 3.68 mm³ without pins (P = 0.024), with corresponding fBIC distances of 2.25 mm and 3.31 mm, respectively (P < 0.001). Conclusions. The addition of rhBMP-2 to CM failed to improve bone regeneration of peri-implant dehiscence defects compared to using an unsoaked CM after 4 weeks. However, the stabilization of CMs using pins positively influenced the outcomes.

Periodontal healing with a preameloblast-conditioned medium in dogs

BACKGROUND AND OBJECTIVE

The predictability of conventional periodontal treatments for damaged periodontal tissue is limited, particularly on the regeneration of new cementum. As signaling molecules, a range of growth factors has been used to promote periodontal regeneration on periodontal ligament (PDL) and cementum defects. A preameloblast-conditioned medium (PA-CM) was prepared from cultured murine apical bud cells, which can differentiate into ameloblasts. We examined the effect of PA-CM on PDL cells and cementoblasts in vitro and evaluated histologically the effects of PA-CM on the regeneration of experimentally induced periodontal defects in vivo.

MATERIAL AND METHODS

In vitro, the effects of PA-CM on the migration of human PDL cells were examined using a scratch wound healing assay and a transwell assay. The differentiation and mineralization potential of PA-CM-treated human PDL cells and murine cementoblastic OCCM-30 cells was examined by real-time polymerase chain reaction and Alizarin red-S staining. In vivo, six mongrel dogs (12-16 kg; 6-8 mo old) were used. Twenty-four roots were replanted with either, (i) only periodontal defects (n = 12; control group), or (ii) periodontal defects and PA-CM treatment (n = 12; experimental group). In the experimental group, the PDL and cementum between notches was removed using a Gracey curette and soaked in 0.08 mL water containing 80 μg of a PA-CM for 2 min. The dogs were killed at 4 and 8 wk post-surgery.

RESULTS

The in vitro results showed that PA-CM stimulated the migration of PDL cells and promoted the differentiation and mineralization of PDL cells and cementoblasts. Real-time polymerase chain reaction analysis revealed stronger expression of Runx2, Osx, OC, Bsp and Cap mRNAs in the PA-CM-treated PDL cells and cementoblasts than those in the control cells. In vivo, newly formed PDL-like tissue and cementum-like tissue were observed partially between the root surfaces and newly formed bone in the experimental group. The regenerated PDL-like tissue in the experimental group was significantly higher than that in the control group at 8 wk (p < 0.05). The replacement resorption on the experimental group was significantly lower than that in the control group at 8 wk (p < 0.05). In addition, the amount of newly formed cementum-like tissue in the experimental group was significantly higher than that in the control group at 4 and 8 wk (p < 0.05).

CONCLUSION

These results suggest that PA-CM has the potential to regenerate periodontal tissues in PDL and cementum defects.

The efficacy of BMP-2 preloaded on bone substitute or hydrogel for bone regeneration at peri-implant defects in dogs

OBJECTIVES

The objective of this experiment was to test whether or not a synthetic bone substitute (SBS) was more effective than a polyethylene glycol hydrogel as a carrier material for bone morphogenetic protein-2 (BMP-2) when attempting to regenerate bone.

MATERIAL AND METHODS

Two identical, box-type dehiscence defects (4 × 4 mm buccolingually and apicocoronally, and 8 mm mesiodistally) were surgically prepared on buccal sides of the left and right edentulous ridge in five beagle dogs. Following implant placement, the defects either received (i) no graft, (ii) SBS+hydrogel, (iii) SBS+BMP-2 loaded hydrogel, and (iv) BMP-2-loaded SBS+hydrogel. The animals were euthanized at 8 weeks postsurgery. Radiographic and histomorphometric analyses were performed.

RESULTS

The hydrogel alone was not able to stabilize the grafted bone particles at 8 weeks, and SBS+hydrogel group did not significantly differ from the control group in all volumetric measurements. On the other hand, extensively regenerated new bone was connected with most of the remaining SBS particles in the BMP-2 groups. The BMP-2 groups exhibited significantly greater new bone formation (10.65 mm(3) and 1.47 mm(2) in the SBS+BMP-2-loaded hydrogel group; 14.17 mm(3) and 0.93 mm(2) in the BMP-2-loaded SBS+hydrogel) than non-BMP-2 groups (1.27 mm(3) and 0.00 mm(2) in the control group; 2.01 mm(3) and 0.19 mm(2) in the SBS+hydrogel group) in volumetric and histomorphometric analyses (P < 0.001). However, there were no significant differences between both BMP-2 groups.

CONCLUSION

BMP-2 could yield enhanced bone regeneration in the critical-size peri-implant defects regardless of whether SBS or hydrogel is used for preloading, although the outcomes seem to be more reproducible with BMP-2 preloaded on SBS.

Acceleration of Bone Regeneration by BMP-2-Loaded Collagenated Biphasic Calcium Phosphate in Rabbit Sinus

PURPOSE

The objective of this study was to determine the effectiveness of collagenated biphasic calcium phosphate (CBCP) as a carrier for bone morphogenetic protein-2 (BMP-2) at the early stage of healing in rabbit sinus.

MATERIAL AND METHODS

In 16 rabbits, BMP-2-loaded CBCP was grafted into one sinus (the BMP group) and saline-soaked CBCP was grafted into another sinus (the CTL group). The groups were assigned randomly. After 2 weeks (n = 8) or 4 weeks (n = 8), radiographic and histological analysis was performed.

RESULTS

Total augmented volume was significantly larger in the BMP group at both healing periods. Furthermore, new bone volume was significantly greater in the BMP group at 4 weeks. Marked bone formation near the schneiderian membrane was found in the BMP groups at the early healing period. At 4 weeks, evenly distributed new bone was observed in the BMP group, whereas the new bone was sparsely distributed in the central portion in the CTL group.

CONCLUSION

It can be concluded that the addition of BMP-2 to CBCP resulted in a greater initial augmented volume as a result of postoperative swelling, which is replaced by early bone formation, and it was prominent near the Schneiderian membrane.

Calcium orthophosphates in dentistry

Dental caries, also known as tooth decay or a cavity, remains a major public health problem in the most communities even though the prevalence of disease has decreased since the introduction of fluorides for dental care. Therefore, biomaterials to fill dental defects appear to be necessary to fulfill customers' needs regarding the properties and the processing of the products. Bioceramics and glass-ceramics are widely used for these purposes, as dental inlays, onlays, veneers, crowns or bridges. Calcium orthophosphates belong to bioceramics but they have some specific advantages over other types of bioceramics due to a chemical similarity to the inorganic part of both human and mammalian bones and teeth. Therefore, calcium orthophosphates (both alone and as components of various formulations) are used in dentistry as both dental fillers and implantable scaffolds. This review provides brief information on calcium orthophosphates and describes in details current state-of-the-art on their applications in dentistry and dentistry-related fields. Among the recognized dental specialties, calcium orthophosphates are most frequently used in periodontics; however, the majority of the publications on calcium orthophosphates in dentistry are devoted to unspecified "dental" fields.

Role of collagen membrane in lateral onlay grafting with bovine hydroxyapatite incorporated with collagen matrix in dogs

Purpose

The objective of this study was to elucidate the role of collagen membranes (CMs) when used in conjunction with bovine hydroxyapatite particles incorporated with collagen matrix (BHC) for lateral onlay grafts in dogs.

Methods

The first, second, and third premolars in the right maxilla of mongrel dogs (n=5) were extracted. After 2 months of healing, two BHC blocks (4 mm×4 mm×5 mm) were placed on the buccal ridge, one with and one without the coverage by a CM. The animals were sacrificed after 8 weeks for histometric analysis.

Results

The collagen network of the membranes remained and served as a barrier. The quantity and quality of bone regeneration were all significantly greater in the membrane group than in the no-membrane group (P<0.05).

Conclusions

The use of barrier membranes in lateral onlay grafts leads to superior new bone formation and bone quality compared with bone graft alone.