Osseous response to implanted natural bone mineral and synthetic hydroxylapatite ceramic in the repair of experimental skull bone defects

Improved new bone formation capacity of hyaluronic acid-bone substitute compound in rat calvarial critical size defect

BACKGROUND

Bone loss of residual alveolar ridges is a great challenge in the field of dental implantology. Deproteinized bovine bone mineral (DBBM) is commonly used for bone regeneration, however, it is loose and difficult to handle in clinical practice. Hyaluronic acid (HA) shows viscoelasticity, permeability and excellent biocompatibility. The aim of this study is to evaluate whether high-molecular-weight (MW) HA combined with DBBM could promote new bone formation in rat calvarial critical size defects (CSDs).

MATERIALS AND METHODS

Rat calvarial CSDs (5 mm in diameter) were created. Rats (n = 45) were randomly divided into 3 groups: HA-DBBM compound grafting group, DBBM particles only grafting group and no graft group. Defect healing was assessed by hematoxylin-eosin staining and histomorphometry 2, 4 and 8 weeks postop, followed by Micro-CT scanning 8 weeks postop. Statistical analyses were performed by ANOVA followed by Tukey's post hoc test with P < 0.05 indicating statistical significance.

RESULTS

All rats survived after surgery. Histomorphometric evaluation revealed that at 2, 4 and 8 weeks postop, the percentage of newly formed bone was significantly greater in HA-DBBM compound grafting group than in the other two groups. Consistently, Micro-CT assessment revealed significantly more trabecular bone (BV/TV and Tb.N) in HA-DBBM compound group than in the other two groups, respectively (P < 0.05). Moreover, the trabecular bone was significantly more continuous (Tb.Pf) in HA-DBBM compound group than in the other two groups, respectively (P < 0.05).

CONCLUSION

HA not only significantly promoted new bone formation in rats calvarial CSDs but also improved the handling ability of DBBM.

Safety and Effectiveness of Bone Allografts for Mastoid Obliteration After Mastoidectomy: A Pilot Study

BACKGROUND AND OBJECTIVES

Various materials are used to perform post-mastoidectomy mastoid obliteration (MO) to reduce the risk of recurrent infections, stasis of secretions, or caloric dizziness. Autologous materials used as fillers for MO tend to be insufficient owing to shrinkage over time or inadequate volume of these substances. Synthetic materials are unsatisfactory for MO because of the risk of rejection and extrusion. We investigated the safety and effectiveness of bone allografts for post-mastoidectomy MO.

SUBJECTS AND METHODS

We reviewed the medical records of patients who underwent mastoidectomy with MO between January 2013 and January 2021. In the MO group, bone allografts were additionally used to fill the residual mastoid cavity. In the canal wall down (CWD) group, all patients underwent CWD mastoidectomy with use of additional inferiorly based mucoperiosteal flaps.

RESULTS

The study included the MO group (23 ears) and the CWD group (53 ears). In the MO group, compared with the preoperative status, we observed a decrease in the tendency of the air-bone gap postoperatively. Compared with the CWD group, the total complication rate showed a decreasing tendency in the MO group.

CONCLUSIONS

No patient showed post-MO shrinkage of the grafted bone allograft or otorrhea. Further large-scale studies are warranted to confirm the advantages of bone allografts for MO, including maintenance with time and sufficient amount.

Application of Three-Dimension Printing Nano-Carbonated-Hydroxylapatite to the Repair of Defects in Rabbit Bone

Introduction

Hydroxylapatite (HAp) is a biodegradable bone graft material with high biocompatibility. However, the clinical application of HAp has been limited due to the poor absorption rate in vivo.

Methods

In this study, carbonated hydroxylapatite (CHAp) with a chemical composition similar to natural bone was synthesized. HAp and CHAp scaffolds were fabricated by 3D printing. Each material was designed by two types of scaffold model with a maximum width of 8 mm and a thickness of 2 mm, ie, structure I (round shape) and structure II (grid shape). Then, the HAp scaffolds were loaded with lutein. These scaffolds were implanted into the 8 mm bone defect on the top of the rabbit skull within 3 hours in the morning. The curative effects of the scaffolds were assessed two months after implantation.

Results

The 3D printed scaffolds did not cause severe inflammation or rejection after implantation. It showed that the porous structures allow bone cells to enter into the scaffolds. Furthermore, CHAp scaffolds were more biocompatible than HAp scaffolds, and showed a higher level of degradation and new bone formation after implantation. Structure II scaffolds with a smaller mineral content degraded faster than structure I, while structure I had better osteoconductive properties than structure II. Besides, the addition of lutein significantly enhanced the rate of new bone formation.

Discussion

The uniqueness of this study lies in the synthesis of 3D printed CHAp scaffolds and the implantation of CHAp in rabbit bone defects. The incorporation of suitable carbonate and lutein into HAp can enhance the osteoinductivity of the graft, and CHAp has a faster degradation rate in vivo, all of which provide a new reference for the research and application of apatite-based composites.

Bone Regeneration of a 3D-Printed Alloplastic and Particulate Xenogenic Graft with rhBMP-2

This study aimed to evaluate the bone regeneration capacity of a customized alloplastic material and xenograft with recombinant human bone morphogenetic protein-2 (rhBMP-2). We prepared hydroxyapatite (HA)/tricalcium phosphate (TCP) pure ceramic bone blocks made using a 3D printing system and added rhBMP-2 to both materials. In eight beagle dogs, a total of 32 defects were created on the lower jaws. The defective sites of the negative control group were left untreated (N group; 8 defects), and those in the positive control group were filled with particle-type Bio-Oss (P group; 12 defects). The defect sites in the experimental group were filled with 3D-printed synthetic bone blocks (3D group; 12 defects). Radiographic and histological evaluations were performed after healing periods of 6 and 12 weeks and showed no significant difference in new bone formation and total bone between the P and 3D groups. The 3D-printed custom HA/TCP graft with rhBMP-2 showed bone regeneration effects similar to that of particulate Bio-Oss with rhBMP-2. Through further study and development, the application of 3D-printed customized alloplastic grafts will be extended to various fields of bone regeneration.

Preliminary Animal Study on Bone Formation Ability of Commercialized Particle-Type Bone Graft with Increased Operability by Hydrogel

The purpose of this study was to evaluate the bone-generating ability of a new bovine-derived xenograft (S1-XB) containing hydrogel. For control purposes, we used Bio-Oss and Bone-XB bovine-derived xenografts. S1-XB was produced by mixing Bone-XB and hydrogel. Cell proliferation and differentiation studies were performed to assess cytotoxicities and cell responses. For in vivo study, 8 mm-sized cranial defects were formed in 16 rats, and then the bone substitutes were transplanted into defect sites in the four study groups, that is, a Bio-Oss group, a Bone-XB group, an S1-XB group, and a control (all n = 4); in the control group defects were left empty. Eight weeks after surgery, new bone formation areas were measured histomorphometrically. In the cell study, extracts of Bio-Oss, Bone-XB, and S1-XB showed good results in terms of the osteogenic differentiation of human mesenchymal stem cells (hMSCs) and no cytotoxic reaction was evident. No significant difference was observed between mean new bone areas in the Bio-Oss (36.93 ± 4.27%), Bone-XB (35.07 ± 3.23%), and S1-XB (30.80 ± 6.41%) groups, but new bone area was significantly smaller in the control group (18.73 ± 5.59%) (p < 0.05). Bovine-derived bone graft material containing hydrogel (S1-XB) had a better cellular response and an osteogenic effect similar to Bio-Oss.

Healing of Experimental Periodontal Defects Following Treatment with Fibroblast Growth Factor-2 and Deproteinized Bovine Bone Mineral

The aim of this study was to investigate the effects of fibroblast growth factor (FGF)-2 used in combination with deproteinized bovine bone mineral (DBBM) on the healing of experimental periodontal defects. Periodontal defects created in rats were treated by FGF-2, DBBM, FGF-2 + DBBM, or left unfilled. Microcomputed tomography, histological, and immunohistochemical examinations were used to evaluate healing. In vitro cell viability/proliferation on DBBM with/without FGF-2 was assessed by WST-1. Cell behavior was analyzed using scanning electron and confocal laser scanning microscopy. Osteogenic differentiation was evaluated by staining with alkaline phosphatase and alizarin red. Bone volume fraction was significantly greater in FGF-2 and FGF-2 + DBBM groups than in other groups at 2 and 4 weeks postoperatively. In histological assessment, newly formed bone in FGF-2 and FGF-2 + DBBM groups appeared to be greater than other groups. Significantly greater levels of proliferating cell nuclear antigen-, vascular endothelial growth factor-, and osterix-positive cells were observed in FGF-2 and FGF-2 + DBBM groups compared to Unfilled group. In vitro, addition of FGF-2 to DBBM promoted cell viability/proliferation, attachment/spreading, and osteogenic differentiation. The combination therapy using FGF-2 and DBBM was similarly effective as FGF-2 alone in the healing of experimental periodontal defects. In certain bone defect configurations, the combined use of FGF-2 and DBBM may enhance healing via promotion of cell proliferation, angiogenesis, and osteogenic differentiation.

Evaluation of New Octacalcium Phosphate-Coated Xenograft in Rats Calvarial Defect Model on Bone Regeneration

Bone graft material is essential for satisfactory and sufficient bone growth which leads to a successful implant procedure. It is classified into autogenous bone, allobone, xenobone and alloplastic materials. Among them, it has been reported that heterogeneous bone graft material has a porous microstructure that increases blood vessels and bone formation, and shows faster bone formation than other types of bone graft materials. We observed new bone tissue formation and bone remodeling using Ti-oss^® (Chiyewon Co., Ltd., Guri, Korea), a heterologous bone graft material. Using a Sprague–Dawley rat calvarial defect model to evaluate the bone healing effect of biomaterials, the efficacy of the newly developed xenograft Ti-oss^® and Bio-Oss^® (Geistilch Pharma AG, Wolhusen, Switzerland). The experimental animals were sacrificed at 8 and 12 weeks after surgery for each group and the experimental site was extracted. The average new bone area for the Ti-oss^® experimental group at 8 weeks was 17.6%. The remaining graft material was 22.7% for the experimental group. The average new bone area for the Ti-oss^® group was 24.3% at 12 weeks. The remaining graft material was 22.8% for the experimental group. It can be evaluated that the new bone-forming ability of Ti-oss^® with octacalcium phosphate (OCP) has the bone-forming ability corresponding to the conventional products.

Cellular responses to deproteinized bovine bone mineral biofunctionalized with bone-conditioned medium

OBJECTIVES

The aim of the study was to investigate whether the osteoinductive properties of bone-conditioned medium (BCM) harvested from cortical bone chips within a clinically relevant short-term period can enhance the biologic characteristics of deproteinized bovine bone mineral (DBBM) in vitro.

MATERIALS AND METHODS

To assess the biofunctionalization of DBBM, the adhesive, proliferative, and differentiation properties of mesenchymal stromal ST2, pre-osteoblastic MC3T3-E1, and primary bone-derived cells grown on BCM-coated DBBM were examined by crystal violet staining of adherent cells, BrdU ELISA, and qRT-PCR, respectively.

RESULTS

BCM extracted within 20 min or 24 h in either Ringer's solution (BCM-RS) or RS mixed with autologous serum (BCM-RS + S) increased the adhesive properties of all three cell types seeded on DBBM. The 20-min BCM-RS preparation appeared more potent than the 24-h preparation. BCM-RS made within 20 min or 24 h had strong pro-proliferative effects on all cell types grown on DBBM. RS + S alone exhibited a considerable pro-proliferative effect, suggesting an impact of the serum on cellular growth. DBBM coated with BCM-RS or BCM-RS + S, made within 20 min or 24 h each, caused a significant induction of osteogenic differentiation marker expression with a higher potency of the BCM-RS + S. Finally, a strong additive effect of fresh bone chips combined with BCM-coated DBBM on the osteogenic differentiation of the three cell types was observed.

CONCLUSIONS

Altogether, the data strongly support the biofunctionalization of DBBM with BCM extracted within a clinically relevant time window of 20 min.

CLINICAL RELEVANCE

Pre-activation of non-osteoinductive biomaterials with BCM, prepared from autologous bone chips during a guided bone regeneration (GBR) procedure, bears the potential of an optimal treatment modality for bone defects in daily practice.

Mastoid cavity obliteration leads to a clinically significant improvement in health-related quality of life

OBJECTIVE

To assess the change in health-related quality of life (HRQoL) in patients undergoing mastoid cavity obliteration.

METHODS

Patients who had undergone canal wall-down mastoidectomy for chronic otitis media with creation of a persistent mastoid cavity and underwent revision tympanomastoid surgery including mastoid cavity obliteration using autologous material were included. Audiological measurements including air conduction (AC) and bone conduction (BC) pure-tone averages (PTA) and the air-bone gap (ABG) were assessed. Health-related Quality of Life (HRQoL) was assessed by the Zurich Chronic Middle Ear Inventory (ZCMEI-21) pre- and postoperatively.

RESULTS

A total of 25 patients (16 females and 9 males; mean age 51.6 years, 14 right and 11 left ears) were included. Patients were reexamined after a mean follow-up period of 9.2 months (SD = 6.5) after obliteration of the mastoid cavity. Compared to the preoperative visit, patients showed a significantly reduced AC PTA at the postoperative visit (mean difference: - 4.1; SD = 10.4, p = 0.045). The mean ZCMEI-21 score changed from 31.7 (SD = 14.5) preoperatively to 17.4 (SD = 15.1) postoperatively (mean difference: - 14.3; SD = 19.1; p = 0.0002). The mean ZCMEI-21 score changes were neither correlated to the AC PTA shift (p = 0.60) nor to the ABG shift (p = 0.66).

CONCLUSIONS

This is the first study reporting a highly significant and clinically important improvement in HRQoL after mastoid cavity obliteration in a prospective setting. The improvement in HRQoL was not correlated to the hearing improvement. As a clinical implication, we provide evidence for a substantial subjective benefit of the surgical obliteration of a symptomatic mastoid cavity and, therefore, encourage this surgical procedure.

Bone union formation in the rat mandibular symphysis using hydroxyapatite with or without simvastatin: effects on healthy, diabetic, and osteoporotic rats

OBJECTIVE

The objective is to compare new bone formation in critical defects in healthy, diabetic, and osteoporotic rats filled with hydroxyapatite (HA) alone and HA combined with simvastatin (SV).

MATERIALS AND METHODS

A total of 48 adult female Sprague-Dawley rats were randomized into three groups (n = 16 per group): Group, 1 healthy; Group 2, diabetics; and Group 3, osteoporotics. Streptozotocin was used to induce type 1 diabetes in Group 2, while bilateral ovariectomy was used to induce osteoporosis in Group 3. The central portion of the rat mandibular symphysis was used as a physiological critical bone defect. In each group, eight defects were filled with HA alone and eight with HA combined with SV. The animals were sacrificed at 4 and 8 weeks, and the mandibles were processed for micro-computed tomography to analyze radiological union and bone mineral density (BMD); histological analysis of the bone union; and immunohistochemical analysis, which included immunoreactivity of vascular endothelial growth factor (VEGF) and bone morphogenetic protein 2 (BMP-2).

RESULTS

In all groups (healthy, diabetics, and osteoporotics), the defects filled with HA + SV presented greater radiological bone union, BMD, histological bone union, and more VEGF and BMP-2 positivity, in comparison with bone defects treated with HA alone.

CONCLUSIONS

Combined application of HA and SV improves bone regeneration in mandibular critical bone defects compared with application of HA alone in healthy, diabetic, and osteoporotic rats.

CLINICAL RELEVANCE

This study might help to patients with osteoporosis or uncontrolled diabetes type 1, but future studies should be done.

Maxillary Sinus Augmentation with Deproteinized Bovine Bone (Bio-Oss®) and Impladent® Dental Implant System Part II. Evaluation of Deprotienized Bovine Bone (Bio-Oss®) and Implant Surface

The objective of this clinical study was to determine the predictability of endosseous implant placed in a maxillary sinus augmented with deproteinized bovine bone (Bio-Oss®). A total of 185 implants (109 titanium and 76 hydroxyapatite- coated) were placed in 77 patients representing 92 sinuses either a one- or two-stage surgical technique. A mixture of venous patient’s blood and Bio-Oss® was used alone within 20 sinuses (Group 1), or in combination with autogenous bone within 72 sinuses (Group 2). Thirty-nine implants were placed in Group 1 and 147 implants were inserted in Group 2. The grafted sinuses were evaluated clinically and radiographically at second stage surgery. According to certain criteria, of the implants placed, only two titanium implants (1.08 %) failed with 98.91 % implant survival. There was no statistically variable difference for the use of hydroxyapatite-coated or titanium implants. The two failed implants were from Group 2. No clinical benefit has been achieved from the combination with autogenous bone (P<0.05). All the grafted sinuses were sufficient to place dental implants of at least 12 mm length (100 % graft success). The results of this short-term study support the hypothesis that Bio-Oss® can be a suitable material for sinus augmentation.

Aspirin promotes osteogenic differentiation of human dental pulp stem cells

Human dental pulp stem cells (hDPSCs) possess self‑renewal and osteogenic differentiation properties, and have been used for orofacial bone regeneration and periodontal treatment. Aspirin has been demonstrated to enhance the regeneration of bone marrow mesenchymal stem cells (MSCs); however, the impact of aspirin on the osteogenic differentiation of hDPSCs remains unknown. In the present study, hDPSCs were characterized by flow cytometry, while their clonogenic potential and multipotency were assessed using alizarin red, Oil red O and alcian blue staining. The effect of aspirin on hDPSC viability was assessed using Cell Counting Kit‑8 assay. Osteogenic capacity was examined by alkaline phosphatase activity, alizarin red staining, reverse transcription‑polymerase chain reaction and western blotting. Furthermore, in vivo cranial defects were established in Sprague‑Dawley rats to evaluate the effect of aspirin on hDPSC‑based bone regeneration. Anorganic bovine bone was used as a bone replacement material and as the carrier for hDPSCs. New bone formation was observed through radiographic and histological analysis. The study demonstrated that hDPSCs expressed MSC markers and possessed multipotency in vitro. Aspirin was non‑toxic to hDPSCs at a concentration of ≤100 µg/ml and enhanced the osteogenesis of hDPSCs in vitro. Aspirin significantly increased hDPSC‑based bone formation in the rat cranial defect model at 8 or 12 weeks post‑implantation (P<0.05). The data suggested that aspirin promotes the osteogenic potential of hDPSCs in vitro and in vivo. Overall, the present study indicated that aspirin improves the bone regeneration capacity of hDPSCs.

Radiographic and Histological Evaluation of the Healing of Extraction Sockets Filled With Bovine-Derived Xenograft: An Experimental Study in Rats

AIM

To evaluate the microenvironment changes in the sockets substituted with bovine-derived xenografts during the early healing period.

MATERIALS AND METHODS

After extraction of the right maxillary incisor of Sprague Dawley rats, 48 rats were randomly divided into 2 groups. The extraction sockets of the test group were filled with Bio-Oss, whereas the control group was allowed to heal without intervention. The bone quality of the extraction sockets was observed through micro-CT and immunohistochemistry.

RESULTS

Micro-CT scanning showed that the bone mineral density in the test group was significantly higher than that in the control group during the early healing period, whereas immunohistochemistry showed that the bone formation-related factors were significantly different between the test and control groups.

CONCLUSIONS

The bovine-derived xenografts may interfere with the healing process of the extraction socket in the early healing stage. Bone formation of the extraction socket was delayed after grafting with bone substitute.

Purification processes of xenogeneic bone substitutes and their impact on tissue reactions and regeneration

Xenogeneic bone substitute materials are widely used in oral implantology. Prior to their clinical use, purification of the former bone tissue has to be conducted to ensure the removal of immunogenic components and pathogens. Different physicochemical methods are applied for purification of the donor tissue, and temperature treatment is one of these methods. Differences in these methods and especially the application of different temperatures for purification may lead to different material characteristics, which may influence the tissue reactions to these materials and the related (bone) healing process. However, little is known about the different material characteristics and their influences on the healing process. Thus, the aim of this mini-review is to summarize the preparation processes and the related material characteristics, safety aspects, tissue reactions, resorbability and preclinical and clinical data of two widely used xenogeneic bone substitutes that mainly differ in the temperature treatment: sintered (cerabone^®) and non-sintered (Bio-Oss^®) bovine-bone materials. Based on the summarized data from the literature, a connection between the material-induced tissue reactions and the consequences for the healing processes are presented with the aim of translation into their clinical application.

Comparison of three block bone substitutes for bone regeneration: long-term observation in the beagle dog

This study aimed to evaluate the impact of three types of block bone substitute material on bone formation and graft resorption in vivo. Standardized bone defects (n = 4 defects/animal) were created in the calvaria of nine dogs. Block bone substitutes made of deproteinized bovine bone mineral (DBBM), beta-tricalcium phosphate (β-TCP) and a mixture alpha-TCP and hydroxyapatite (α-TCP/HA) were inserted into the bone defects. A fourth defect was left untreated (empty). All sites were covered with a collagenous membrane. Block biopsies were harvested at 3, 6 and 12 months post-implantation and analyzed by micro-CT and histology. Biomaterial absorption was minimal and incorporation within the defect margin was good for all biomaterials. However, β-TCP demonstrated a relatively greater volume of new bone formation and less residual material volume when compared with DBBM and α-TCP/HA. Conversely, α-TCP/HA showed higher osteoconductive potential and a greater new bone area compared with the other two biomaterials. The block bone substitutes used in the present in vivo study showed advantageous in terms of maintenance of their original form in bony defect. However, the positive impact of all biomaterials on new bone formation and replacement of bone was minor even at 12 months. These findings indicate that block bone substitutes are not well suited to vertical bone augmentation. Further investigations are required to improve the insufficient new bone volume for promising clinical results.

A prospective controlled trial comparing xenograft/autogenous bone and collagen-stabilized xenograft for maxillary sinus augmentation-Complications, patient-reported outcomes and volumetric analysis

OBJECTIVE

Compare maxillary sinus augmentation (MSA) using two different materials-anorganic bovine bone mineral (ABBM) + autogenous bone (AB) (control group) vs. collagen-stabilized ABBM (test group) in terms of complications, patient-reported outcome measures (PROMs) and volumetric analysis.

MATERIALS AND METHODS

Sixty patients underwent sinus augmentation (30 control + 30 test group). Intra- and postoperative complications were recorded. PROMs measured the impact of grafting on daily activities, pain and morbidity. CT scans were used to measure graft volume, ridge height, material selection and degree of contact of graft-to-surrounding sinus walls. Dental implant placement parameters were also recorded.

RESULTS

All complications were minor and did not prevent completion of the augmentation or subsequent implant placement. Schneiderian membrane perforation was the most frequently encountered complication. Both treatment groups reported moderate limitation in the 1st 48 hr post-surgery but little or none by day 3 or 4. Jaw opening, chewing and bruising were significantly higher in the control group. The impact on work and social life was moderate initially but reduced to little or none by the 2nd day. Mild to moderate pain and interference to daily activities were reported for the first 3 days requiring the use of NSAIDs only. A mean graft volume of 1.46 cm³ (±0.77) was calculated in the control group and 1.27 cm³ (±0.65) in the test group. Extent of contact between graft and surrounding sinus walls had a significant impact on bone volume. Shorter (8 mm) implants were utilized more frequently in the test group, which was also more likely to require additional vertical augmentation, but this was not statistically significant.

CONCLUSION

MSA using a lateral wall approach is safe and associated with mild to moderate pain and restrictions to daily activities for 48-72 hr. Patients' reports of morbidity were greater with autogenous bone harvesting. Collagen-stabilized ABBM provides comparable bone volume to AB + ABBM that is sufficient for placement of implants of adequate size with no need for further vertical augmentation. Engaging the surrounding sinus walls had a significant positive impact on graft volume.

Histological Evaluation of Bone Repair with Hydroxyapatite: A Systematic Review

The aim of this study was to evaluate the morphological bone response in animal experiments by applying hydroxyapatite grafts in critical and non-critical size bone defects. Current report followed the guidelines established by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Animal experiments were selected by assessing repair of bone defects with hydroxyapatite as bone graft and with blood clot only as control. Eight articles were identified in specialized literature and included in the meta-analysis. Statistical analysis was carried out with a random-effect model (p = 0.05). Subgroup analyses were further performed to investigate bone repair in critical and non-critical bone defects. Comprehensive analysis of bone repair outcome showed a statistically significant difference between hydroxyapatite and blood clot control (p < 0.05). Subgroup analyses showed statistically significant difference for critical bone defects (p < 0.05). No statistically significant difference was reported in non-critical bone defects (p > 0.05). Although animal studies revealed a high risk of bias and results should be interpreted with caution, the literature suggests that non-critical bone defects may heal spontaneously and without the need of a bone graft. Conversely, when critical-size defects are present, the use of hydroxyapatite bone graft improves the bone repair process.

Repair of segmental radial defect with autologous bone marrow aspirate and hydroxyapatite in rabbit radius: A clinical and radiographic evaluation

AIM

Finding an ideal bone substitute to treat large bone defects, delayed union and nonunions remain a challenge for orthopedic surgeons and researchers. Several studies have been conducted on bone regeneration; each has its own advantages and disadvantages. The aim of this study was to evaluate the effect of a combination of hydroxyapatite (HA) powder with autologous bone marrow (BM) aspirate on the repair of segmental radial defect in a rabbit model.

MATERIALS AND METHODS

A total of 36 male and adult New Zealand rabbit with a mean weight of 2.25 kg were used in this study. Approximately, 5 mm defect was created in the mid-shaft of the radius to be filled with HA powder in the control group "HA" (n=18) and with a combination of HA powder and autologous BM aspirate in the test group "HA+BM" (n=18). Animals were observed daily for healing by inspection of the surgical site, and six rabbits of each group were sacrificed at 30, 60, and 90 post-operative days to perform a radiographic evaluation of defect site.

RESULTS

Obtained results revealed a better and more rapid bone regeneration in the test group: Since the defect was rapidly and completely filled with mature bone tissue after 90 days.

CONCLUSION

Based on these findings, we could infer that adding a BM aspirate to HA is responsible of a better regeneration process leading to a complete filling of the defect.

Could Calcified Triglyceride Bone Cement Be an Alternative Graft Material in Maxillary Sinus Augmentation?

The ideal graft material for maxillary sinus augmentation is still a matter of controversy and the search for a more appropriate bone substitute for use continues. The aim of this study was to evaluate bone formation as a sign of the regeneration following maxillary sinus augmentation in rabbits using 3 different biomaterials, one of which is a newly developed graft material; calcified triglyceride bone cement (CTBC).Twenty-one New Zealand rabbits were used and randomly divided into 3 groups. Bilateral maxillary sinus augmentation was carried out and autogenous bone (AB), bovine hydroxyapatite (BHA), and CTBC were administered. Maxillary sinuses were dissected after fourth and eighth weeks of the operation. The bone formation was evaluated by stereological and histopathological analysis and the data were analyzed statistically.When the volume of primary bone is compared, statistically significant differences were found among all groups at both of the fourth and eighth weeks. The highest value was obtained from AB applied group. In BHA and CTBC applied groups, active bone formation, osseointegration of graft materials were observed at both fourth and eighth weeks. In CTBC applied group, primary bone formation was only seen as linked to the continuation of parent sinus bony wall.The efficiency of primary bone formation of CTBC was found less than AB and BHA. Of the 3 graft materials tested, BHA is the strongest alternative to AB graft for maxillary sinus augmentation.

Two Composite Bone Graft Substitutes for Maxillary Sinus Floor Augmentation: Histological, Histomorphometric, and Radiographic Analyses

OBJECTIVE

To histologically, histomorphometrically, and radiographically compare clinical performance of 2 composite bone graft substitutes for maxillary sinus floor augmentation (MSFA).

MATERIALS AND METHODS

Partially or totally edentulous patients requiring MSFA underwent grafting procedures using a 2:1 mixture of biphasic calcium sulfate (CS) and deproteinized bovine bone (group CB) or biphasic CS and alloplast (group CA). Grafts were allowed to heal for 5 months before placing the implants. During implant surgery, bone samples were collected from grafted areas for histology and histomorphometry. Graft height was analyzed using cone beam computed tomography.

RESULTS

Sixteen patients completed the study. Mean percentages of new bone were 34.40% ± 18.91% and 36.71% ± 15.32% for the CA and CB groups, respectively; percentages of residual graft particles were 6.98% ± 5.09% and 5.52% ± 4.12%, respectively. The only significant finding was a greater graft height loss in the CA group (24.44% ± 6.52% vs 14.60% ± 4.58%).

CONCLUSION

Both graft substitutes were integrated in bone, confirming their biocompatibility and effectiveness for MSFA. The CB group showed less bone height loss than the CA group.

Benefits of mineralized bone cortical allograft for immediate implant placement in extraction sites: an in vivo study in dogs

Purpose

The aim of the present study was to evaluate the effectiveness of using a mineralized bone cortical allograft (MBCA), with or without a resorbable collagenous membrane derived from bovine pericardium, on alveolar bone remodeling after immediate implant placement in a dog model.

Methods

Six mongrel dogs were included. The test and control sites were randomly selected. Four biradicular premolars were extracted from the mandible. In control sites, implants without an allograft or membrane were placed immediately in the fresh extraction sockets. In the test sites, an MBCA was placed to fill the gap between the bone socket wall and implant, with or without a resorbable collagenous membrane. Specimens were collected after 1 and 3 months. The amount of residual particles and new bone quality were evaluated by histomorphometry.

Results

Few residual graft particles were observed to be closely embedded in the new bone without any contact with the implant surface. The allograft combined with a resorbable collagen membrane limited the resorption of the buccal wall in height and width. The histological quality of the new bone was equivalent to that of the original bone. The MBCA improved the quality of new bone formation, with few residual particles observed at 3 months.

Conclusions

The preliminary results of this animal study indicate a real benefit in obtaining new bone as well as in enhancing osseointegration due to the high resorbability of cortical allograft particles, in comparison to the results of xenografts or other biomaterials (mineralized or demineralized cancellous allografts) that have been presented in the literature. Furthermore, the use of an MBCA combined with a collagen membrane in extraction and immediate implant placement limited the extent of post-extraction resorption.

BoneCeramic graft regenerates alveolar defects but slows orthodontic tooth movement with less root resorption

INTRODUCTION

BoneCeramic (Straumann, Basel, Switzerland) can regenerate bone in alveolar defects after tooth extraction, but it is unknown whether it is feasible to move a tooth through BoneCeramic grafting sites. The objective of this study was to investigate 3-dimensional real-time root resorption and bone responses in grafted sites during orthodontic tooth movement.

METHODS

Sixty 5-week-old rats were randomly assigned to 3 groups to receive BoneCeramic, natural bovine cancellous bone particles (Bio-Oss; Geistlich Pharma, Wolhusen, Switzerland), or no graft, after the extraction of the maxillary left first molar. After 4 weeks, the maxillary left second molar was moved into the extraction site for 28 days. Dynamic bone microstructures and root resorption were evaluated using in-vivo microcomputed tomography. Stress distribution and corresponding tissue responses were examined by the finite element method and histology. Mixed model analysis of variance was performed to compare the differences among time points with Bonferroni post-hoc tests at the significance level of P <0.05.

RESULTS

The BoneCeramic group had the least amount of tooth movement and root resorption volumes and craters, and the highest bone volume fraction, trabecular number, and mean trabecular thickness, followed by the Bio-Oss and the control groups. The highest stress accumulated in the cervical region of the mesial roots.

CONCLUSIONS

BoneCeramic has better osteoconductive potential and induces less root resorption compared with Bio-Oss grafting and naturally recovered extraction sites.

Incorporation of aligned PCL-PEG nanofibers into porous chitosan scaffolds improved the orientation of collagen fibers in regenerated periodontium

The periodontal ligament (PDL) is a group of highly aligned and organized connective tissue fibers that intervenes between the root surface and the alveolar bone. The unique architecture is essential for the specific physiological functionalities of periodontium. The regeneration of periodontium has been extensively studied by researchers, but very few of them pay attention to the alignment of PDL fibers as well as its functionalities. In this study, we fabricated a three-dimensional multilayered scaffold by embedding highly aligned biodegradable poly (ε-caprolactone)-poly(ethylene glycol) (PCE) copolymer electrospun nanofibrous mats into porous chitosan (CHI) to provide topographic cues and guide the oriented regeneration of periodontal tissue. In vitro, compared with random group and porous control, aligned nanofibers embedded scaffold could guide oriented arrangement and elongation of cells with promoted infiltration, viability and increased periodontal ligament-related genes expression. In vivo, aligned nanofibers embedded scaffold showed more organized arrangement of regenerated PDL nearly perpendicular against the root surface with more extensive formation of mature collagen fibers than random group and porous control. Moreover, higher expression level of periostin and more significant formation of tooth-supporting mineralized tissue were presented in the regenerated periodontium of aligned scaffold group. Incorporation of aligned PCE nanofibers into porous CHI proved to be applicable for oriented regeneration of periodontium, which might be further utilized in regeneration of a wide variety of human tissues with a specialized direction.

STATEMENT OF SIGNIFICANCE

The regeneration of periodontium has been extensively studied by researchers, but very few of them give attention to the alignment of periodontal ligament (PDL) fibers as well as its functionalities. The key issue is to provide guidance to the orientation of cells with aligned arrangement of collagen fibers perpendicular against the root surface. This study aimed to promote oriented regeneration of periodontium by structural mimicking of scaffolds. The in vitro and in vivo performances of the scaffolds were further evaluated to test the topographic-guiding and periodontium healing potentials. We also think our research may provide ideas in regeneration of a wide variety of human tissues with a specialized direction.

Induction of multinucleated giant cells in response to small sized bovine bone substitute (Bio-Oss™) results in an enhanced early implantation bed vascularization

Purpose:

The host tissue reaction to the xenogeneic bone substitute Bio-Oss™ (Geistlich Biomaterials, Wolhousen, Switzerland) was investigated focusing on the participating inflammatory cells and implantation bed vascularization.

Materials and Methods:

Bio-Oss™ was implanted subcutaneously into CD1 mice for up to 60 days and analyzed by means of specialized histological and histomorphometrical techniques after explantation.

Results:

Bio-Oss™ induced within the first 15 days an early high vascularization combined with a marked presence of multinucleated giant cells. The latter cells were associated mainly with the smaller sized granules within the implantation bed. Toward the end of the study the number of multinucleated giant cells decreased while the tissue reaction to the larger granules was mainly mononuclear.

Conclusion:

The results of the present study showed that smaller xenogeneic bone substitute granules induce multinucleated giant cells, whereas the larger-sized ones became integrated within the implantation bed by means of a mononuclear cell-triggered granulation tissue. Obviously, the presence of multinucleated giant cells within biomaterial implantation beds is not only related to the type of synthetic bone substitute material, but also to the granule size of the natural-based xenogeneic bone substitute material.

Efficacy of Connective Tissue with and without Periosteum in Regeneration of Intrabony Defects

Background and aims. Connective tissue grafts with and without periosteum is used in regenerative treatments of bone and has demonstrated successful outcomes in previous investigations. The aim of present study was to evaluate the effectiveness of connective tissue graft with and without periosteum in regeneration of intrabony defects.

Materials and methods. In this single-blind randomized split-mouth clinical trial, 15 pairs of intrabony defects in 15 patients with moderate to advanced periodontitis were treated by periosteal connective tissue graft + ABBM (test group) or non-periosteal connective tissue graft + ABBM (control group). Probing pocket depth, clinical attachment level, free gingival margin position, bone crestal position, crest defect depth and defect depth to stent were measured at baseline and after six months by surgical re-entry. Data was analyzed by Student’s t-test and paired t-tests (α=0.05).

Results. Changes in clinical parameters after 6 months in the test and control groups were as follows: mean of PPD reduction: 3.1±0.6 (P<0.0001); 2.5±1.0 mm (P<0.0001), CAL gain: 2.3±0.9 (P<0.0001); 2.2±1.0 mm (P<0.0001), bone fill: 2.2±0.7 mm (P<0.0001); 2.2±0.7 mm (P<0.0001), respectively. No significant differences in the position of free gingival margin were observed during 6 months compared to baseline in both groups.

Conclusion. Combinations of periosteal connective tissue graft + ABBM and non-periosteal connective tissue graft + ABBM were similarly effective in treating intrabony defects without any favor for any group. Connective tissue and perio-steum can be equally effective in regeneration of intrabony defects.

Inorganic polyphosphate adsorbed onto hydroxyapatite for guided bone regeneration: an animal study

Inorganic polyphosphate (poly(P)) is recognized as a therapeutic agent that promotes fibroblast growth factor and enhances osteogenic differentiation, and in vivo, when adsorbed onto interconnected porous calcium hydroxyapatite (IP-CHA) enhances bone regeneration. The present study focused on the effect of poly(P) adsorbed onto IP-CHA granules (Poly(P)/IP-CHA) in guided bone regeneration (GBR). Dental implants were placed into the edentulous mandibular areas of five Beagle-Labrador hybrid dogs with screw expose on the buccal side, and then bone defects were filled Poly(P)/IP-CHA (test) or IP-CHA (control). After 12 weeks, histological evaluation and histomorphometrical analysis were performed. Newly-bone formation around exposed implant screw was clearly detected in the test-group. The ratio for regenerated bone height in the test group versus the control-group was 85.6±20.2 and 62.6±23.8, respectively, with no significant difference, while, that for bone implant contact was significantly higher (67.9±11.8 and 48.8±14.1, respectively). These findings indicate that Poly(P)/IP-CHA enhances bone regeneration in GBR.

Maxillary Sinus Augmentation with Autologous and Heterologous Bone Graft: A Clinical and Radiographic Report of Immediate and Delayed Implant Placement

PURPOSE

The aim of this study was to evaluate cumulative survival rate of implants placed on augmented maxillary sinus using a mixture of autologous bone harvested from the maxillary tuberosity and bovine-derived HA and to assess the height of the grafted material through radiographic evaluation.

METHODS

Thirty-five patients were treated with maxillary sinus augmentation and 93 implant fixtures were installed. The height of the augmented sinus and the gain of bone volume were measured by Cone Beam CT Scan and intraoral radiographs immediately after augmentation and up to 48 months subsequently. Changes in the height of the sinus graft material were calculated radiographically.

RESULTS

The cumulative survival rate was 98.92 % in all 93 implants. Additionally, normal healing process without any complication was observed in all patients. The original sinus height was a mean of 4.52 mm (range 2.0-6.4 mm) and the augmented sinus height was a mean of 14.1 mm (range 12.0-16.5 mm) after the surgery. The bone volume gain was a mean 9.613 mm (range 7-13 mm).

CONCLUSIONS

Within the limitations of this study, it would appear from the clinical and radiographic results that the sinus lift procedure with autologous bone graft harvested from the maxillary tuberosity combined with deproteinized bovine bone allows for a predictable outcome regarding the amount of bone formation in sinus floor augmentation and the immediate placement of implants, when possible, is recommended.

Alveolar ridge preservation with the socket-plug technique utilizing an alloplastic putty bone substitute or a particulate xenograft: a histological pilot study

Following tooth extraction, ridge preservation procedures are employed to regenerate bone in the extraction socket, limit consequent ridge resorption, and provide a stable base for implant placement. The purpose of this study is to histologically evaluate and compare bone regeneration in extraction sockets grafted with either a putty alloplastic bone substitute or particulate anorganic bovine xenograft utilizing the socket-plug technique. Nineteen patients underwent 20 tooth extractions and ridge preservation following a standardized protocol. Ten sites were grafted with calcium phosphosilicate putty (CPS group) and the remaining 10 with anorganic bovine bone substitute (BO group). Patients were recalled after 4-6 months to evaluate the bone regeneration and to proceed with implant placement. A bone core was obtained during the implant procedure from each site and was used for histologic analysis. Histomorphometry revealed that residual graft values were significantly higher in the BO group (25.60% ± 5.89%) compared to the CPS group (17.40% ± 9.39%) (P < .05). The amount of new bone regenerated was also statistically significant higher in the alloplast group (47.15% ± 8.5%) as compared to the xenograft group (22.2% ± 3.5%) (P < .05). Results suggest that ridge preservation using a putty calcium phosphosilicate alloplastic bone substitute demonstrates more timely graft substitution and increased bone regeneration when compared to an anorganic bovine bone xenograft.

Clinical, Histological, and Histomorphometrical Analysis of Maxillary Sinus Augmentation Using Inorganic Bovine in Humans: Preliminary Results

The aim of the present study was to evaluate bone formation after maxillary sinus augmentation using bovine bone substitute material Bio-Oss alone by means of clinical, histological, and histomorphometrical examination of human biopsies. Deproteinized bovine bone (DPBB, Bio-Oss) was used to fill cavities after elevation of the sinus mucosa following major sinus pneumatization. Twenty patients with edentulous posterior maxillae were treated with 20 sinus augmentation procedures using a 2-stage technique. Residual lateral maxillary bone height was less than 3 mm. Forty-nine Straumann endosseous implants were used to complete the implant-prosthetic rehabilitation. Forty cylinder-shaped bone biopsies were taken from the augmented maxillary region 8 months after grafting during the second-stage surgery before implant placement. All implants were loaded 3 months after insertion, and no failures were recorded. Histomorphometrical analysis showed an average percentage of newly formed bone of 17.6% (±2.8%) and a proportion of residual bone substitute material of 29.9% (±4.9%) of the total biopsy area. Intimate contact between newly formed bone and Bio-Oss was detected along 28.2% (±6.8%) of the particle surfaces. The results also showed that in all cases, the DPBB granules had been interconnected by bridges of vital newly formed bone. Inorganic bovine bone appears to be biocompatible and osteoconductive, and it can be used with success as a bone substitute in maxillary sinus augmentation procedures.

Melatonin and oral cavity

While initially the oral cavity was considered to be mainly a source of various bacteria, their toxins and antigens, recent studies showed that it may also be a location of oxidative stress and periodontal inflammation. Accordingly, this paper focuses on the involvement of melatonin in oxidative stress diseases of oral cavity as well as on potential therapeutic implications of melatonin in dental disorders. Melatonin has immunomodulatory and antioxidant activities, stimulates the proliferation of collagen and osseous tissue, and acts as a protector against cellular degeneration associated with aging and toxin exposure. Arising out of its antioxidant actions, melatonin protects against inflammatory processes and cellular damage caused by the toxic derivates of oxygen. As a result of these actions, melatonin may be useful as a coadjuvant in the treatment of certain conditions of the oral cavity. However, the most important effect of melatonin seems to result from its potent antioxidant, immunomodulatory, protective, and anticancer properties. Thus, melatonin could be used therapeutically for instance, locally, in the oral cavity damage of mechanical, bacterial, fungal, or viral origin, in postsurgical wounds caused by tooth extractions and other oral surgeries. Additionally, it can help bone formation in various autoimmunological disorders such as Sjorgen syndrome, in periodontal diseases, in toxic effects of dental materials, in dental implants, and in oral cancers.

Calcium phosphate bioceramics fabricated from extracted human teeth for tooth tissue engineering

Bioceramic tooth powders were prepared via heat treatment of extracted human teeth using sintering temperatures between 600°C and 1200°C, and their properties were investigated for potential tooth tissue engineering. The sintered human tooth powders were characterized using thermal analysis (thermogravimetric analysis (TG) and differential thermal analysis (DTA)), field emission scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, and Fourier transformed infrared (FTIR) spectroscopy. Additionally, the phase constitutions and chemical homogeneities of the composite samples were examined using a quantitative chemical analysis with inductively coupled plasma spectroscopy. The results revealed that the annealing process produced useful hydroxyapatite-based bioceramic biomaterials when annealed above 1000°C. The FTIR spectra and the TG/DTA thermograms of the tooth powders indicated the presence of organic compounds, which were completely removed after annealing at temperatures above 1000°C. The tooth powders annealed between 1000°C and 1200°C had good characteristics as bioceramic biomaterials. Furthermore, the biocompatibility of each tooth powder was evaluated using in vitro and in vivo techniques; our results indicate that the prepared human tooth powders have great potential for tooth tissue engineering applications.

Expression of MMP-2, 9 and 13 in newly formed bone after sinus augmentation using inorganic bovine bone in human

BACKGROUND AND OBJECTIVE

The aim of the present study was to analyse the expression of MMP-2, MMP-9 and MMP-13 in newly formed bone following maxillary sinus augmentation using inorganic bovine bone substitute, because these MMPs play a major role in bone remodeling and bone resorption.

MATERIAL AND METHODS

Deproteinized bovine bone (Bio-Oss(®)) was used to fill cavities after elevating the sinus mucosa. Twenty patients with edentulous posterior maxilla were treated with 20 sinus-augmentation procedures using a two-stage technique. Forty-nine Straumann(®) endosseous implants were used to complete the implant-prosthetic rehabilitation. One cylinder-shaped bone biopsy from each patient was taken from the augmented maxillary region using trephine burs at the second stage of surgery, 8 months after grafting. A biopsy was also taken as a control from the upper molar region from six different patients who did not undergo the sinus procedure. All biopsies were subjected to biochemical analysis and staining for TRAP.

RESULTS

No implant losses or failures occurred. The large number of TRAP-positive multinucleated osteoclasts in resorption lacunae indicated that the resorption was very active in all grafts, in contrast with the control group. Zymography and western blot analysis demonstrated a significantly increased expression of MMP-2, MMP-9 and MMP-13 in the newly formed bone compared with controls (p < 0.05).

CONCLUSION

The quantity of osteoclastic cells and the increased expression of proteolytic enzymes suggest that 8 months after grafting, inorganic bovine bone is slowly resorbing and is the site of important remodeling of the newly formed bone by means of resorption and synthesis.