Evaluation of a hydroxyapatite-crosslinked fish gelatin membranes.

Background/purpose: Porcine collagen is widely used in regenerative therapies to generate membranes for bone augmentation. However, porcine or bovine gelatin or collagen is often not appropriate for patients with creed and religious beliefs or for allergic reasons. In this study, we evaluated the potential of fish gelatin to generate membranes. Materials and methods: Fish gelatin and hydroxyapatite (HAp) were used at three different ratios (2:0, 2:1, 2:1.5, and 2:2) to prepare gelatin-hydroxyapatite (G-HAp) membranes via freeze-drying and heat-crosslinking. The surface morphology and cell attachment of G-HAp membranes were observed using scanning electron microscopy and confocal laser microscopy. G-HAp membrane was placed at the bottom of a well plate, and MC3T3-E1 cells were seeded on it. Cell viability and cytotoxicity were tested after 1 and 3 days of culture. Alkaline phosphatase (ALP) and alizarin red staining was performed at 10 and 21 days, respectively. Results: Viability of cells on G-HAp membrane with the gelatin:HAp ratio of 2:1.5 was significantly higher than that on membranes with other gelatin:HAp ratios. ALP and alizarin red staining showed that ALP-positive areas and calcium deposition were the highest on G-HAp membrane with the gelatin:HAp ratio of 2:1. These membranes showed negligible cytotoxicity. Conclusion: Fish-derived G-HAp membranes have the potential to promote osteogenic differentiation of MC3T3-E1 cells with negligible cytotoxicity.

Comparative analysis of the in vivo kinetic properties of various bone substitutes filled into a peri-implant canine defect model.

PURPOSE: Deproteinized bovine bone or synthetic hydroxyapatite are 2 prevalent bone grafting materials used in the clinical treatment of peri-implant bone defects. However, the differences in bone formation among these materials remain unclear. This study evaluated osteogenesis kinetics in peri-implant defects using 2 types of deproteinized bovine bone (Bio-Oss® and Bio-Oss/Collagen®) and 2 types of synthetic hydroxyapatite (Apaceram-AX® and Refit®). We considered factors including newly generated bone volume; bone, osteoid, and material occupancy; and bone-to-implant contact. METHODS: A beagle model with a mandibular defect was created by extracting the bilateral mandibular third and fourth premolars. Simultaneously, an implant was inserted into the defect, and the space between the implant and the surrounding bone walls was filled with Bio-Oss, Bio-Oss/Collagen, Apaceram-AX, Refit, or autologous bone. Micro-computed tomography and histological analyses were conducted at 3 and 6 months postoperatively (Refit and autologous bone were not included at the 6-month time point due to their rapid absorption). RESULTS: All materials demonstrated excellent biocompatibility and osteoconductivity. At 3 months, Bio-Oss and Apaceram-AX exhibited significantly greater volumes of formation than the other materials, with Bio-Oss having a marginally higher amount. However, this outcome was reversed at 6 months, with no significant difference between the 2 materials at either time point. Apaceram-AX displayed notably slower bioresorption and the largest quantity of residual material at both time points. In contrast, Refit had significantly greater bioresorption, with complete resorption and rapid maturation involving cortical bone formation at the crest at 3 months, Refit demonstrated the highest mineralized tissue and osteoid occupancy after 3 months, albeit without statistical significance. CONCLUSIONS: Overall, the materials demonstrated varying post-implantation behaviors in vivo. Thus, in a clinical setting, both the properties of these materials and the specific conditions of the defects needing reinforcement should be considered to identify the most suitable material.

Integrated Bone Formation Through In Vivo Endochondral Ossification Using Mesenchymal Stem Cells.

Conventional bone regeneration therapy using mesenchymal stem cells (MSCs) is difficult to apply to bone defects larger than the critical size because it does not have a mechanism to induce angiogenesis. Implanting artificial cartilage tissue fabricated from MSCs induces angiogenesis and bone formation in vivo via endochondral ossification (ECO). Therefore, this ECO-mediated approach may be a promising bone regeneration therapy in the future. An important aspect of the clinical application of this ECO-mediated approach is establishing a protocol for preparing enough cartilage to be implanted to repair the bone defect. It is especially not practical to design a single mass of grafted cartilage of a size that conforms to the shape of the actual bone defect. Therefore, the cartilage to be transplanted must have the property of forming bone integrally when multiple pieces are implanted. Hydrogels may be an attractive tool for scaling up tissue-engineered grafts for endochondral ossification to meet clinical requirements. Although many naturally derived hydrogels support MSC cartilage formation in vitro and ECO in vivo, the optimal scaffold material to meet the needs of clinical applications has yet to be determined. Hyaluronic acid (HA) is a crucial component of the cartilage extracellular matrix and is a biodegradable and biocompatible polysaccharide. Here, we show that HA hydrogels have excellent properties to support in vitro differentiation of MSC-based cartilage tissue and promote endochondral bone formation in vivo.

Peri-implantitis management by resective surgery combined with implantoplasty and Er:YAG laser irradiation, accompanied by free gingival graft: a case report.

The optimal method for decontamination of implant surfaces for peri-implantitis treatment remains controversial. In recent years, erbium-doped yttrium aluminum garnet (Er:YAG) laser irradiation and implantoplasty (IP) (i.e. mechanical modification of the implant) have been reported to be effective in decontaminating implant surfaces during the surgical treatment. Also, a lack of adequate keratinized mucosa (KM) around the implant is known to be associated with more plaque accumulation, tissue inflammation, attachment loss, and mucosal recession, increasing the risk of peri-implantitis. Therefore, free gingival graft (FGG) has been recommended for gaining adequate KM around the implant. However, the necessity of acquiring KM for the treatment of peri-implantitis using FGG remains unclear. In this report, we applied the apically positioned flap (APF) as resective surgery for peri-implantitis treatment in conjunction with IP and Er:YAG laser irradiation to polish/clean the implant surface. Furthermore, FGG was conducted simultaneously to create additional KM, which increased the tissue stability and contributed to the positive results. The two patients were 64 and 63 years old with a history of periodontitis. The removal of granulation tissue and debridement of contaminated implant surfaces were performed with Er:YAG laser irradiation post flap elevation and then modified smooth surfaces mechanically using IP. Er:YAG laser irradiation was also utilized to remove the titanium particles. In addition, we performed FGG to increase the width of KM as a vestibuloplasty. Peri-implant tissue inflammation and progressive bone resorption were not observed, and both patients maintained good oral hygiene conditions until the 1-year follow-up appointment. Bacterial analysis via high-throughput sequencing revealed proportional decreases in bacteria associated with periodontitis (Porphyromonas, Treponema, and Fusobacterium). To the best of our knowledge, this study is the first to describe peri-implantitis management and bacterial change before and after procedures by resective surgery combined with IP and Er:YAG laser irradiation for peri-implantitis treatment, accompanied by FGG for increasing KM around the implants.

A modal analysis of implant-supported overdentures installed on differently positioned sets of dental implants.

This study evaluated the three vibration characteristics, namely, natural frequency, damping ratio, and natural mode, together with maximum displacement of a two-implant-supported overdenture (IOD) at different locator attachment positions using experimental modal analysis (EMA). Edentulous mandibular models with a gingival thickness of 1 mm or 3 mm were prepared, into which dental implants were placed using a fully guided surgical template designed with simulation software, the locator abutments were fastened, and the IODs were then fabricated. The implant positions were bilaterally marked at the lateral incisor, first premolar, and first molar regions. EMA was performed by hammering the test structures to measure the impulse response and obtain the vibration characteristics (n = 5). The Kruskal-Wallis test was performed for natural frequency and maximum displacement, and the Games-Howell test for damping ratio. The significance level was set at α = 0.05. The study indicated that the gingival thickness had a significant effect on the vibration characteristics. Moreover, the natural frequency and damping ratio results showed that the vibration subsided faster when the attachment was placed on the molar implants in the thick gingival model. Furthermore, according to the effect of lateral force on IODs, the difference in maximum displacement between the anterior and posterior regions of the IOD was smaller when the attachments were designed on the pair of lateral incisors. Thus, within the limits of this experiment, our results suggested that two anterior implant-supported IODs are preferable treatment designs in terms of vibration engineering, especially when the gingiva is thick; the molar attachment design could be considered for thin gingival conditions. The differences in gingival thickness and abutment position affected the vibration characteristics of the IOD. Further in vivo studies would be necessary to validate the implant positions and their IOD designs for the mandibular edentulous shapes and the occlusal relationship.

Postoperative morphological changes over time of vascularized scapular bone used for mandibular reconstruction: A retrospective cohort study.

BACKGROUND: Currently, sequential morphological changes of vascularized scapular bone for mandibular reconstruction have remained unreported. METHODS: We retrospectively analyzed 18 patients with defects on the lateral segment of the mandible who underwent postoperative computed tomography (CT) scanning at 1, 6, 12, and 24 months postoperatively. Using the cross-sectional coronal CT images during each assessment, we measured the height and thickness of the grafted scapular bone at points 10 and 30 mm away from the mesial segment and evaluated their differences over time. Then, the relationship between the morphological changes of the grafted scapular bone and the distance from the mesial bone segment, the number of occlusal supports on the contralateral side of the mandible, and the correlation of sex and age were evaluated. RESULTS: The height of the grafted scapular bone decreased by approximately 11% and its thickness increased by 14% within 24 months postoperatively. The bone thickness increase was greater at point 30 mm from the mesial bone segment. Patients with two occlusal contacts (premolar and molar) on the contralateral side had a significantly higher rate of bone thickness increase. Furthermore, the graft morphology was not associated with age or sex. CONCLUSION: A vascularized scapular bone thickens over time, which depends on the distance from the mesial bone segment and the occlusal contact regions on the contralateral side of the mandible.

Construction of Hybrid Cell Spheroids Using Cell-Sized Cross-Linked Nanogel Microspheres as an Artificial Extracellular Matrix.

The introduction of functional material supports or spacers into cell spheroids increases the free volume, allowing oxygen, nutrients, and waste products to diffuse in and out more freely. Here, a biocompatible polysaccharide spacer material was investigated. Microspheres were prepared by cross-linking cholesterol-modified pullulan (CHP) nanogels with poly(ethylene glycol) (PEG). The ratio of modified CHP nanogel to PEG cross-linker was optimized to give uniform microspheres with an average diameter of approximately 14 µm. Rhodamine B-labeled microspheres showed a homogeneous assembly with bone marrow-derived mesenchymal stem cells (1:1 ratio) to create hybrid cell spheroids. The addition of the cross-linked nanogel spacers did not affect the cell viability, indicating that the microspheres provided a biocompatible scaffold that supported cell proliferation. In addition, the microspheres were stable under culture conditions over 14 days. The hybrid cell spheroids were scaled up to millimeter size to demonstrate their potential as a transplantable treatment, and the cells were found to maintain their high viability. The hybrid cell spheroids are expected to support the production of organoids.

Hydroxyapatite Nanoparticles as Injectable Bone Substitute Material in a Vertical Bone Augmentation Model.

AIM: The aim of this in vivo study was to evaluate the utility of bone graft gel containing hydroxyapatite nanoparticles in promoting bone regeneration in a mouse model of vertical bone augmentation. MATERIALS AND METHODS: Gel implants with high and low viscosity were compared for their bone regenerating ability. Bone formation at 12 weeks and material reactions were observed radiographically and histologically. RESULTS: Radiological analysis showed that most bone augmentation area in the graft material occurred in the fourth week after surgery regardless of the viscosity of the gel, and then gradually decreased. The volume of bone augmentation area was greater in the high-viscosity implant group than in the low-viscosity implant group at all time points, the difference was statistically significant at 8 and 12 weeks. Histological evaluation indicated that the new bone area was significantly smaller in the high-viscosity implant group. CONCLUSION: Gelatinous graft materials containing hydroxyapatite nanoparticles were confirmed to be useful in vertical bone augmentation.

Crosslinked nanogel-based porous hydrogel as a functional scaffold for tongue muscle regeneration.

Surgical resection in tongue cancer can impair speech and swallowing, reducing quality of life. There is a need for biomaterials that can regenerate tongue muscle tissue defects. Ideally, such a biomaterial would allow controlled release of therapeutic proteins, support the survival and differentiation of therapeutic cells, and promote tongue muscle regeneration in vivo. The aim of the current study was to assess these factors in an acryloyl group-modified crosslinked nanogel, consisting of cholesterol-bearing pullulan hydrogel nanoparticles, to determine its potential as a regenerative therapeutic following tongue resection. The hydrogel demonstrated substantial porosity and underwent slow biodegradation. When loaded with a model protein, the gel enabled sustained protein release over two weeks in serum, with no initial burst release. Mouse myoblasts demonstrated adhesion to the hydrogel and cell survival was observed up to one week. Gel-encapsulated myoblasts demonstrated normal myotube differentiation. Myoblast-loaded gels were implanted in a tongue defect in mice, and there was a significant increase in newly-regenerated myofibers in gel-implanted animals. The developed biomaterial platform demonstrates significant potential as a regenerative treatment following tongue resection, as it facilitates both protein and cell-mediated therapy, and stimulates tongue muscle regeneration in vivo.

Preparation of dentin standard samples for age estimation based on increased aspartic acid racemization rate by heating.

Age estimation in adults based on aspartic acid racemization (AAR) provides fewer errors and higher precision than that based on bone morphology for the identification of cadavers. The technique has been established in some labs as a routine method. However, as the essential requisites for the technique, a wide age range of teeth of the same type as the target tooth must be collected for calibration for each examination. We investigated whether dentin standard samples could be prepared by increasing the AAR rate via heat. Powdered dentin was prepared from a maxillary first premolar (13 years) and heated for 0-72 h at 110 °C. The extent of AAR increased significantly with heating time and the correlation was strong (r = 0.913; p < 0.01). Similar results were found for a mandibular canine (24 years, r = 0.948; p < 0.01) and a maxillary third molar (20 years, r = 0.944; p < 0.01). We attempted to estimate the age of four maxillary first premolars of persons aged 25-58 years by using the heated samples (18 years, 12 h to 7 days). The differences between the actual and estimated ages were within ±5 years. The stability of the AAR rates in the powdered dentin during storage at 22-25 °C, 4 °C, and -30 °C was examined after 1 year and no significant changes had occurred. We were able to prepare dentin standard samples and created a calibration curve. This is a pilot study that needs to be validated before it can be used in forensic practice.

Degradation and interaction with bone of magnesium alloy WE43 implants: A long-term follow-up in vivo rat tibia study.

The aim of this in vivo study was to examine the degradation and biocompatibility of the WE43 magnesium alloy containing magnesium yttrium, rare earth elements, and zirconium over a one-year long-term follow-up period. Additionally, we compared anodized WE43 implants with monolithic ones and clarified the effect of the anodization. WE43 cylindrical implants with and without anodization (length, 10 mm; diameter, 0.3 mm) were transplanted into the rat tibia. In both groups, the development of corrosion and the change in implant volume were evaluated by in vivo micro-computed tomography until 12 months, and the bone tissue reaction was observed histologically. In the monolithic WE43 implants, hydrogen gas was evident until 14 days and the volume loss was 36.3% after 12 months. In the anodized WE43 implants, the development of hydrogen gas was inhibited and the volume loss was 27.7% after 12 months. The anodized WE43 implants showed a significantly slower corrosion process in the early phase. Therefore, these implants may require a prolonged period to degrade completely and may even resist complete degradation. At one year post surgery, bone maturation progressed and lamellar bone structure developed around the implant in both groups. In conclusion, the WE43 implants showed good long-term stability and biocompatibility in bone tissue.

Treatment of oral cancers during pregnancy: a case-based discussion.

BACKGROUND: Malignancies occur in approximately 1:1000 pregnancies; the most common being breast (46%) and hematological (18%) malignancies. Oral cancers account for only 2% of all cancers in pregnant women, and there are no standard guidelines for the treatment of oral cancer during pregnancy. METHODS: Between 2007 and 2014, our department managed 1109 patients with oral cancers; four (0.4%) had tongue carcinomas during pregnancy. These cases were retrospectively reviewed. RESULTS: The four women were aged 29-39 (median 32.5) years. Two underwent partial glossectomy at 39 and 40 weeks' gestation, respectively, one received radiotherapy at 17 weeks' gestation, and one underwent supraomohyoid neck dissection and hemi-glossectomy with a forearm flap reconstruction. CONCLUSION: In addition to tumor factors, the wishes of the patient and her family, gestational age, and fetal and maternal conditions are important factors in deciding on a treatment protocol. Moreover, treatment decisions require multidisciplinary approach.

Appropriate surgical margin for odontogenic myxoma: a review of 12 cases.

OBJECTIVE: Odontogenic myxoma (OM) is a rare benign tumor that is frequently nonencapsulated and invades the surrounding bone, resulting in a high risk of recurrence. However, the optimal surgical technique and appropriate surgical margin remains controversial. Here, we report our clinical investigation of 12 patients with OM diagnosed histopathologically. STUDY DESIGN: We retrospectively reviewed the records of 12 patients treated at our institution. Osteotomy or bone shaving with enucleation was generally performed with 5-mm bony margins from the radiologic extent of the tumor. RESULTS: One half of the cases occurred in the maxilla and the other half in the mandible. Treatment for maxillary OM was enucleation in 2 patients and maxillectomy in 4 patients. Treatment for mandibular OM was enucleation with shaving of the surrounding bone in 1 patient and segmental mandibulectomy in 5 patients. Radiographs of surgical specimen removed by segmental mandibulectomy indicated that the mean distance between the tumor and the margin was 5.4 (range 3.4-7.0) mm. Tumor recurrence was noted in 1 patient who had undergone enucleation alone. CONCLUSION: The 1-cm surgical margin for OM, as reported conventionally, might not be necessary. A prospective study is needed to determine the appropriate surgical margin for OM.

Comparison of magnesium alloys and poly-l-lactide screws as degradable implants in a canine fracture model.

The aims of this study were to evaluate in vivo the biological responses to implants composed of biodegradable anodized WE43 (containing magnesium yttrium, rare earth elements and zirconium; Elektron SynerMag®) magnesium alloy, monolithic WE43 magnesium alloy and poly-l-lactic acid (PLLA), which are commonly used materials in clinic settings, and to evaluate the effectiveness of the materials as bone screws. The effectiveness of the magnesium alloy implants in osteosynthesis was evaluated using a bone fracture model involving the tibia of beagle dogs. For the monolithic WE43 implants, radiological, and histological evaluation revealed that bone trabeculae around the implanted monolithic WE43 decreased because of an inflammatory response. However, there was no damage due to hydrogen gas or inflammatory response in the bone tissue around the anodized WE43 implants. After 4 weeks, all the PLLA implants (n = 3) had broken but the WE43 implants had not (n = 6). These results suggest that the WE43 implants had sufficient strength to fix bone fractures at load-bearing sites in orthopedic and oral maxillofacial surgery. Therefore, these biodegradable magnesium alloys are good candidates for replacing biodegradable polymers. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1282-1289, 2016.

Functional outcomes with dental prosthesis following simultaneous mandibulectomy and mandibular bone reconstruction.

PURPOSE: This study sought to ascertain masticatory outcomes in patients who underwent mandibulectomy or hemimandibulectomy together with mandibular bone reconstruction to allow for placement of a removable dental prosthesis. METHODS: Perioperative changes in masticatory performance, masticatory ability for solids, and patients' subjective satisfaction were evaluated for 101 patients who had mandibulectomy immediately followed by bone reconstruction. Differences in masticatory performance and masticatory ability for solids after surgery were determined according to occlusal support after surgery and whether the patient was wearing a removable dental prosthesis or not. Occlusal support areas were classified according to Eichner's classification. RESULTS: Preoperative Eichner's class A patients had no experience of wearing a dental prosthesis before surgery and after surgery did not want one. Their masticatory performance was better than that of patients who wanted a dental prosthesis after surgery. Retrospective analysis of postoperative Class B and C patients revealed that masticatory performance was lower in those who wanted a dental prosthesis than in those who did not want one. When patients wore a dental prosthesis after surgery, masticatory performance was markedly improved over not wearing it. All patients' subjective satisfaction was significantly improved after surgery. CONCLUSIONS: Increasing the number of occlusal support areas by wearing a removable dental prosthesis after simultaneous mandibulectomy or hemimandibulectomy and mandibular bone reconstruction may improve masticatory functions. Those professional involved in the rehabilitation for the mandibular defect should be mindful that masticatory functions after such surgeries were affected by the masticatory functions before surgery and the number of occlusal support areas after surgery.

Effects of platelet-poor plasma, platelet-rich plasma, and platelet-rich fibrin on healing of extraction sockets with buccal dehiscence in dogs.

Alveolar bone resorption generally occurs during healing after tooth extraction. This study aimed to evaluate the effects of platelet-poor plasma (PPP), platelet-rich plasma (PRP), and platelet-rich fibrin (PRF) on healing in a ridge-augmentation model of the canine socket with dehiscence of the buccal wall. The third mandibular premolars of 12 beagle dogs were extracted and a 3 mm buccal dehiscence from the alveolar crest to the buccal wall of the extraction socket was created. These sockets were then divided into four groups on the basis of the material used to fill the sockets: PPP, PRP, PRF, and control (no graft material) groups. Results were evaluated at 4 and 8 weeks after surgery. The ultrastructural morphology and constructs of each blood product were studied by a scanning electron microscope (SEM) or calculating concentrations of platelets, fibrinogen, platelet-derived growth factor, and transforming growth factor-ß. A total of five microcomputed tomography images of specimens were selected for measurement, and the area occupied by the newly formed bone as well as the horizontal bone width were measured. Moreover, decalcified tissue specimens from each defect were analyzed histologically. The median area of new bone at 4 and 8 weeks and median horizontal bone width at 8 weeks were the highest in the PPP group. However, bone maturation in the PRF and the PRP groups was more progressed than that in the PPP and control groups. By SEM findings, the PRF group showed a more highly condensed fibrin fiber network that was regularly arranged when compared with the PPP and PRP groups. The growth factors released from platelets in PRP indicated higher concentrations than that in PRF. Under more severe conditions for bone formation, as in this experiment, the growth factors released from platelets had a negative effect on bone formation. This study showed that PPP is an effective material for the preservation of sockets with buccal dehiscence.

Effect of platelet-rich plasma on bone engineering with an alloplastic substitute containing BMP2.

A robust method for inducing bone-formation without an autograft has not been established. Currently, both platelet-rich plasma (PRP) and bone morphogenetic protein (BMP) have been widely investigated for their clinical use in such cases. However, their synergistic effect is still controversial and previously shown diversity of this effect depends on various factors such as the bone substitutes involved. In this study, we investigated the synergistic effect of PRP and BMP2 on an alloplastic substitute as potentiators to induce in vivo bone-formation. A 10 mm diameter bony defect in rabbit calvarium was reconstructed using biphasic calcium phosphate (BCP) ceramics with or without PRP, recombinant human (rh) BMP2, and their combination. At 6 and 12 weeks after implantation, rabbits were euthanized and the radiographic and histomorphometric features of bone reconstruction were analyzed. The results showed that defects filled by rhBMP2/BCP with or without PRP had high bone density at 6 and 12 weeks in radiological evaluation. However, in histomorphometric analysis, the defects filled by rhBMP2/BCP with PRP showed significant new bone formation compared with that by rhBMP2/BCP without PRP, especially at 6 weeks. We propose that the synergistic effect of PRP and rhBMP2 gives highly osteoinductive properties to alloplastic substitutes in vivo.

Application of a new material (ß-TCP/collagen composites) in extraction socket preservation: an experimental study in dogs.

PURPOSE: A bone defect model simulating an extraction socket with buccal dehiscence was designed to investigate the usefulness of a composite of beta-tricalcium phosphate (ß-TCP) and a collagen sponge, ß-TCP/collagen (TCP/Col) for socket preservation. MATERIALS AND METHODS: Following the extraction of the maxillary second and third premolars of 13 beagle dogs, a bone defect with buccal dehiscence (5 × 3 × 7 mm) was prepared. The defects were filled with either TCP/Col, ?-TCP, collagen, or left intact (control) and evaluated at 4 and 8 weeks after surgery. A total of three micro-computed tomography (micro-CT) images were selected, and the area size occupied by the newly formed bone and residual TCP was measured. Newly formed bone and residual TCP in the bone defect site of the specimens was also measured and evaluated. RESULTS: No evidence of postoperative infection was found in all cases. At 4 weeks after surgery, the TCP granule was retained in the bone defects and active bone formation was observed in the TCP/Col group and the ß-TCP group, whereas in the collagen and the control groups, connective tissue grew into the defect. In the TCP/Col and ß-TCP groups, morphologically well-preserved alveolar ridges were observed; most TCP granules grafted in the defects were resorbed and only a few residuals were evident at 8 weeks after surgery. CONCLUSIONS: These results exhibited that the TCP/Col composites could sufficiently maintain bone width and height for the preservation of the extraction socket with buccal dehiscence while preventing epithelial in-growth. In addition, TCP/Col in an easily handled spongeous form could provide a better intraoral manipulation capability than TCP granules alone and was considered to be suitable as a bone grafting material used for alveolar ridge preservation.

The effect of covering materials with an open wound in alveolar ridge augmentation using beta-tricalcium phosphate: an experimental study in the dog.

PURPOSE: This study aimed to examine the effectiveness of a grafting technique using beta-tricalcium phosphate (Β-TCP) covered with different materials in alveolar bone defects with dehiscences. MATERIALS AND METHODS: In five beagle dogs, all premolars in the mandible were extracted bilaterally. After a 12-week healing period, two bone defects (length, 5 mm; width, 5 mm; depth, 7 mm) were created on each side of the mandible, and the buccal bone plate was resected. The four bone defects were randomly assigned to one of the following treatments: group 1, Β-TCP alone (TCP group); group 2, Β-TCP graft covered with collagen sponge (TCP+collagen group); group 3, Β-TCP graft covered with free buccal mucosa (TCP+mucosa group); group 4, no treatment (control group). The microarchitecture of the regenerated bone was observed using microcomputed tomography, and the area of newly formed bone was measured. Specimens from each defect were selected and subjected to histologic and histomorphometric analysis; areas of newly formed bone and the ridge width were measured in the specimens. RESULTS: Significant differences were found between the control group and all test groups. The median horizontal width of the ridge 2 mm from the top of the alveolar crest in the TCP+mucosa group was significantly greater than that of the TCP group. There was no significant difference between the TCP+mucosa and TCP+collagen groups in any measurement. CONCLUSIONS: Application of Β-TCP grafts to alveolar bone defects with dehiscence and covering of the open wound with free buccal mucosa or collagen sponge may be useful for ridge augmentation. Compared to no treatment or leaving the wound uncovered, these approaches resulted in more new bone formation and provided adequate horizontal mandibular width.

Reduction of bone resorption by the application of platelet-rich plasma (PRP) in bone grafting of the alveolar cleft.

OBJECTIVE: We evaluated the effectiveness of platelet-rich plasma (PRP) on the regeneration of autogenous cancellous bone and marrow grafted in the alveolar cleft. DESIGN: Twenty patients with alveolar clefts were examined; 6 were the control group and received cancellous bone and marrow grafts without PRP, while the remaining 14 comprised the PRP group and received grafts with PRP. Prior to surgery, 50 ml of blood was withdrawn and 5 ml of PRP gel produced through centrifugal separation. The bone graft mixed with PRP was then packed into the alveolar cleft. Postoperative bone density was assessed as the aluminium-equivalent value on occlusal X-ray films in a qualitative analysis. Quantitative evaluation of regenerated bone was made with computed tomography and panoramic radiographs at 1 month, 6 months and 1 year after surgery. RESULTS: Satisfactory bone bridging formation was observed in all patients without any complications. The bone density of the PRP group was lower than that of the control group at 1 week, but the same after 1 month. The added PRP reduced the resorption of regenerated bone postoperatively. CONCLUSION: Autogenous cancellous bone grafting with PRP, which significantly reduces postoperative bone resorption, is a reliable technique for alveolar bone grafting of cleft patients.