Localized ridge augmentation with autografts and barrier membranes

Guided Bone Regeneration Using Barrier Membrane in Dental Applications

Guided bone regeneration (GBR) is a widely used technique in preclinical and clinical studies due to its predictability. Its main purpose is to prevent the migration of soft tissue into the osseous wound space, while allowing osseous cells to migrate to the site. GBR is classified into two main categories: resorbable and non-resorbable membranes. Resorbable membranes do not require a second surgery but tend to have a short resorption period. Conversely, non-resorbable membranes maintain their mechanical strength and prevent collapse. However, they require removal and are susceptible to membrane exposure. GBR is often used with bone substitute graft materials to fill the defect space and protect the bone graft. The membrane can also undergo various modifications, such as surface modification and biological factor loading, to improve barrier functions and bone regeneration. In addition, bone regeneration is largely related to osteoimmunology, a new field that focuses on the interactions between bone and the immune system. Understanding these interactions can help in developing new treatments for bone diseases and injuries. Overall, GBR has the potential to be a powerful tool in promoting bone regeneration. Further research in this area could lead to advancements in the field of bone healing. This review will highlight resorbable and non-resorbable membranes with cellular responses during bone regeneration, provide insights into immunological response during bone remodeling, and discuss antibacterial features.

Enhanced Bone Formation by Rapidly Formed Bony Wall over the Bone Defect Using Dual Growth Factors

BACKGROUND

In guided bone regeneration (GBR), there are various problems that occur in the bone defect after the wound healing period. This study aimed to investigate the enhancement of the osteogenic ability of the dual scaffold complex and identify the appropriate concentration of growth factors (GF) for new bone formation based on the novel GBR concept that is applying rapid bone forming GFs to the membrane outside of the bone defect.

METHODS

Four bone defects with a diameter of 8 mm were formed in the calvaria of New Zealand white rabbits each to perform GBR. Collagen membrane and biphasic calcium phosphate (BCP) were applied to the bone defects with the four different concetration of BMP-2 or FGF-2. After 2, 4, and 8 weeks of healing, histological, histomorphometric, and immunohistochemical analyses were conducted.

RESULTS

In the histological analysis, continuous forms of new bones were observed in the upper part of bone defect in the experimental groups, whereas no continuous forms were observed in the control group. In the histomorphometry, The group to which BMP-2 0.5 mg/ml and FGF-2 1.0 mg/ml was applied showed statistically significantly higher new bone formation. Also, the new bone formation according to the healing period was statistically significantly higher at 8 weeks than at 2, 4 weeks.

CONCLUSION

The novel GBR method in which BMP-2, newly proposed in this study, is applied to the membrane is effective for bone regeneration. In addition, the dual scaffold complex is quantitatively and qualitatively advantageous for bone regeneration and bone maintenance over time.

In vivo evaluation of a collagen membrane in bone neoformation: A morphological and histomorphometric study

OBJECTIVE

Guided bone regeneration (GBR) is a technique that involves the placement of mechanical barriers to protect the blood clot, and create an isolated space to prevent competition from epithelial and connective tissues in bone augmentation treatments. Collagen membranes stand out from other materials available for performing regenerative surgeries, and are widely used because of their ability to promote cell adhesion and homeostasis, and their biocompatibility, ease of handling, and low immunogenicity. In this context, researchers have investigated xenogenic membranes/barriers that cost less and have slower resorption rates. The current study aimed to assess the osteogenic potential induced by a crosslinked, synthesized xenogenic membrane 100 µm thick when applied in vivo to critical defects in rat calvaria.

MATERIAL AND METHODS

Critical size defects were created in the calvaria of thirty male Wistar rats, and randomly divided into the following two groups: G1 - clot covered with a commercial xenogenic membrane (Lumina-Coat®, Criteria, Brazil), and G2 - clot covered with a synthesized xenogenic membrane. The animals were euthanized after 7, 15 and 30 days, and samples of calvaria were processed to perform morphometric evaluations to measure bone neoformation in the defect region. In addition, ultrastructural characterization of the collagen membranes was performed by scanning electron microscope. The quantitative analyses were carried out by adopting a significance level of 5%.

RESULTS

The ultrastructural characterization revealed that the synthesized membrane had thicker collagen fibers and a more cohesive surface, compared with the Lumina-Coat® collagen membrane (G1). There was no significant difference in bone neoformation between the membranes (p>0.05), at any of the time periods analyzed. The bone quantification area increased significantly over time for both membranes (p<0.05).

CONCLUSION

The synthesized membrane exhibited morphological characteristics similar to those of the commercial membrane evaluated, allowed potentially active participation in the bone neoformation process, and served as a low-cost alternative for GBR procedures.

Long-Term Outcome of Dental Implants in Immediate Function Inserted on Autogenous Grafted Bone

Background: There is a need for long-term evidence of immediate function dental implants inserted in grafted bone. The aim of this retrospective study was to investigate the outcome of full-arch rehabilitations supported by implants in grafted bone. Methods: Thirty-six patients (women: 24; men: 12; average age: 53.5 years) were included (225 implants). Primary outcome measure: to assess implant cumulative success rates evaluated through life tables. Secondary outcome measures: to evaluate implant and prosthetic survival, marginal bone loss, and the incidence of both biological and mechanical complications. Results: Twenty-five implants were unsuccessful giving a dental implant CS rate of 88.1% at 14 years and a 76.8% survival estimation (Kaplan−Meier) using the patient as the unit of analysis. No prosthesis was lost. Average MBL at 10 years was 2.01 mm. The incidence of biological complications was 36%, with smoking affecting it significantly (p < 0.001). The incidence of mechanical complications was 86.1% (45.2% and 54.8% in provisional and definitive prosthesis, respectively. Conclusions: The rehabilitation of atrophic maxillae through dental implants in immediate function inserted in grafted bone is a valid treatment alternative, despite the relevant rate of implant failures and incidence of complications.

Healing Patterns of Non-Collagenated Bovine and Collagenated Porcine Xenografts Used for Sinus Floor Elevation: A Histological Study in Rabbits

Objective: To compare healing of collagenated and non-collagenated xenografts used for maxillary sinus floor elevation. Materials and Methods: Two different xenografts were used: deproteinized bovine bone (DBBM group) and collagenated corticocancellous porcine bone (collagenated group). Healing was studied after 2, 4, and 8 weeks. The loss of dimensions of the elevated area and the percentages of new bone, xenograft remnants, osteoclastic zones, vessels, inflammatory infiltrates, and soft tissues were analyzed. Three regions were evaluated: close to the bone walls (bone wall region), subjacent the sinus mucosa (submucosa region), and the center of the elevated area (middle region). The primary variables were the percentage of new bone and xenograft remnants. Results: Between 2 and 8 weeks, the elevated areas showed a reduction of 16.3% and 52.2% in the DBBM and collagenated groups, respectively (p < 0.01 between the two areas after 8 weeks). After 8 weeks, the highest content of new bone was observed in the bone wall region, which was higher in the collagenated group than in the DBBM group (41.6% and 28.6%, respectively; p < 0.01). A similar quantity of new bone was found between the two groups in other regions. A higher percentage of vessels in all regions evaluated (p < 0.01) and soft tissue in the sub-mucosa region (p < 0.05) was found in the collagenated group than in the DBBM group. Conclusions: The present study showed that both xenografts allowed new bone formation. In comparison with the non-collagenated xenograft, the collagenated xenograft underwent higher resorption, resulting in greater shrinkage of the elevated space after sinus lifting and a higher content of new bone in the regions close to the bone walls. Clinical relevance: In this study, the region adjacent to the bone wall showed the highest new bone content. This region resembles the base of the sinus, closest to the sinus floor and walls, and is the most important region from a clinical point of view because it is where the implant will be installed. Residues of the biomaterial remained after 8 weeks of healing. Other reports have shown that these biomaterial residues may interfere with the integration of implants.

Custom Bone Regeneration (CBR): An Alternative Method of Bone Augmentation-A Case Series Study

We performed this clinical study in order to evaluate the reliability of the Guided Bone Regeneration (GBR) surgical technique through the use of customized CAD CAM titanium meshes (Yxoss CBR^® Reoss) in order to show an alternative method of bone augmentation.

MATERIALS AND METHODS

Nine patients presenting 10 bone defects were referred to solve oral dysfunction due to edentulous atrophic ridges. Guided bone regeneration was performed with titanium meshes combined with autogenous bone grafting and heterologous bovine bone mineral grafting, and exclusively a "poncho technique" soft tissue approach for all the cases. After a mean 9 months of graft healing (range 6-12 months), titanium meshes were removed, and implant surgery was subsequently performed. The results we obtained were positive in terms of volumetric increases in height, length and thickness of the atrophic ridges without biological complications detectable before implant surgery.

RESULTS

Out of nine, one site met titanium mesh exposure: however, in all 10 sites a three-dimensional volumetric bone implementation was obtained. The statistical results were estimated by uploading and superimposing cbct scans before and after CBR surgery for each patient, so it was possible evaluate the maximum linear vertical and horizontal bone gain through dedicated Cad Cam software (Exocad GmbH^®). The average horizontal gain was 6.37 ± 2.17 mm (range 2.78-9.12 mm) and vertical gain was 5.95 ± 2.06 mm (range 2.68-9.02 mm). A total of 18 implants were placed into the grafted sites with a 100% survival rate (clearly they are relative percentages to be compared to the short time elapsed).

CONCLUSIONS

The results we obtained in this study suggest that this CBR procedure (Yxoss^® by Reoss) is reliable and safe for bone regeneration to allow implant-prosthetic restoration in horizontal, vertical and combined bone defects. The soft tissue management is diriment: all the cases were managed with a "poncho" flap approach to decrease exposure complication.

3D-printed bi-layered polymer/hydrogel construct for interfacial tissue regeneration in a canine model

OBJECTIVES

There are complications in applying regenerative strategies at the interface of hard and soft tissues due to the limited designs of constructs that can accommodate different cell types in different sites. The problem originates from the challenges in the adhesion of dissimilar materials, such as polymers and hydrogels, that can be suitable for regenerating different tissues such as bone and soft tissues. This paper presents a design of a new hybrid construct in which a polymer (polycaprolactone (PCL)) membrane firmly adheres to a layer of hydrogen (gelatin).

METHODS

PCL membranes with defined size and porosity were fabricated using 3D printing. The gelatin layer was attached to the PCL membranes using the aminolysis procedure. We have examined this construct for the application of Guided Bone Regeneration (GBR) as a typical surgical regenerative procedure of the oral cavity at the interface of bone and soft tissue. Complete in vitro and in vivo investigations on canine tibia bone defects have been performed. Histological analyses for fibrosis morphometric and bone morphometric evaluation, as well as bone-fibrosis histological grading and CBCT imaging, were conducted.

RESULTS

Chemical and morphological studies of the membrane proved that gelatin was uniformly attached to the aminolyzed PCL membranes. The in vitro and in vivo studies indicated the membrane's biocompatibility, mechanical stability, and barrier function for the GBR application. Furthermore, in vitro study showed that the membranes could improve osteogenesis and the regeneration of bone defects. The results illustrated that the mean bone density in the membrane groups was about three times more than that of the control group.

SIGNIFICANCE

The fabricated 3D-printed hybrid Gelatin/PCL bi-layered membrane can be a good candidate for interfacial tissue engineering and a promising membrane for GBR procedure.

Complications in bone-grafting procedures: Classification and management

Bone-regenerative interventions aiming to restore deficient alveolar ridges, such as the use of block grafts or through the application of guided bone-regeneration principles, have reported positive outcomes in the published scientific literature. These interventions, however, are invasive, and hence, intraoperative and/or postoperative complications may occur. The types of complications and their severity may vary from the exposure of the biomaterial (membrane or graft) to postsurgical infections, neurosensorial disturbances, occurrence of hemorrhage, and pain, etc. The aim of the present narrative review was to search the available scientific evidence concerning the incidence of these complications, their effect on treatment outcomes, their clinical management and, finally, strategies aimed at prevention. Exposure of the barrier membrane or the block graft is the most common complication associated with oral regenerative interventions. To manage these complications, depending on the extent of the exposure and the presence or absence of concomitant infections, therapeutic measures may vary, from the topical application of antiseptics to the removal of the barrier membrane or the block graft. Regardless of their treatment, the occurrence of these complications has been associated with patient selection, with compliant patients (eg, nonsmokers) having a lower reported incidence of complications. Similarly, surgical factors such as correct flap elevation and a tensionless closure are of obvious importance. Finally, to prevent the incidence of complications, it appears prudent to utilize whenever possible less invasive surgical interventions.

Interdisciplinary management of recession defects on maxillary single tooth implants: Diagnosis and treatment strategies

OBJECTIVE

One of the most common complications with dental implants placed in the smile zone is the development of mid-facial recession, creating an undesirable esthetic result. When deciding how to remediate these clinical scenarios, the question becomes whether it may be feasible to save the problematic implant or if it is more predictable to remove the implant and start all over again. However, patients may be invested emotionally, physically, and financially in the implant and remediation may be a viable option depending on the diagnosis of the specific issues at hand and multi-disciplinary clinical execution.

CLINICAL SIGNIFICANCE

What is crucial to understand in order to remediate these cases is answering four separate criteria: (1) is the implant in a restorable position, (2) is the implant healthy, (3) is the implant placed at an adequate depth, and (4) are components available to restore the implant.

CONCLUSIONS

Two different clinical reports are presented that demonstrate various treatment remedies when saving implants in the esthetic zone.

Enhanced osteoinductive capacity of poly(lactic-co-glycolic) acid and biphasic ceramic scaffolds by embedding simvastatin

OBJECTIVES

This study evaluated the effect of embedding simvastatin (SIM) on the osteoinductive capacity of PLGA + HA/βTCP scaffolds in stem cells from human exfoliated deciduous teeth (SHED).

MATERIALS AND METHODS

Scaffolds were produced by PLGA solvent dissolution, addition of HA/βTCP, solvent evaporation, and leaching of sucrose particles to impart porosity. Biphasic ceramic particles (70% HA/30% βTCP) were added to the PLGA in a 1:1 (w:w) ratio. Scaffolds with SIM received 1% (w:w) of this medication. Scaffolds were synthesized in a disc-shape and sterilized by ethylene oxide. The experimental groups were (G1) PLGA + HA/βTCP and (G2) PLGA + HA/βTCP + SIM in non-osteogenic culture medium, while (G3) SHED and (G4) MC3T3-E1 in osteogenic culture medium were the positive control groups. The release profile of SIM from scaffolds was evaluated. DNA quantification assay, alkaline phosphatase activity, osteocalcin and osteonectin proteins, extracellular calcium detection, von Kossa staining, and X-ray microtomography were performed to assess the capacity of scaffolds to induce the osteogenic differentiation of SHED.

RESULTS

The release profile of SIM followed a non-liner sustained-release rate, reaching about 40% of drug release at day 28. Additionally, G2 promoted the highest osteogenic differentiation of SHED, even when compared to the positive control groups.

CONCLUSIONS

In summary, the osteoinductive capacity of poly(lactic-co-glycolic) acid and biphasic ceramic scaffolds was expressively enhanced by embedding simvastatin.

CLINICAL RELEVANCE

Bone regeneration is still a limiting factor in the success of several approaches to oral and maxillofacial surgeries, though tissue engineering using mesenchymal stem cells, scaffolds, and osteoinductive mediators might collaborate to this topic.

Horizontal Ridge Augmentation: A Comparison between Khoury and Urban Technique

Simple Summary

With the emergence of novelty regeneration techniques in the implant dentistry field, the professional may have some queries about which one to use in their daily practice. No systematic review, to date, analyzes the horizontal gains achievable with the two main procedures for bone regeneration: the Khoury technique, which uses split blocks obtained from the patient himself, or the Urban technique, which employs membranes to contain the biomaterials. Regarding this paper, the reader will be able to decide if any of these options is adequate for the indication required.

Abstract

Purpose. The objective of this systematic review was to evaluate and compare the clinical efficacy of horizontal alveolar ridge augmentation techniques described by Khoury and Urban. Methods. A systematic electronic search in the MEDLINE databases, SCOPUS, WOS, and the Cochrane Central Register of Controlled Trials (CENTRAL) as well as a manual search, were conducted independently by two reviewers up to July 2021. Results. Six studies met the pre-established inclusion criteria and were included in the descriptive analysis. Due to the heterogeneity found across the included studies, meta-analysis could not be performed. Horizontal bone gain was between 3.93 ± 0.9 mm and 5.02 ± 0.8 mm with the Khoury technique and between 3.9 ± 0.9 mm and 5.68 ± 1.42 mm with the Urban technique. Similar complication rates were reported in both groups: infection (7%), in the Khoury technique, and membrane exposure (3.2–13.6%), in the Urban technique, being the most frequent events. Conclusions. Both techniques were found to be effective, in terms of clinical bone gain, for horizontal alveolar ridge gain. Nevertheless, available literature is limited, and there is a lack of comparative studies to better evaluate the results.

Addition of autogenous bone chips to deproteinized bovine bone mineral does not have additional benefit in lateral ridge augmentation-A preclinical in vivo experimental study

OBJECTIVE

To compare the outcome after extensive lateral guided bone regeneration using deproteinized bovine bone mineral (DBBM) with or without autogenous bone chips in a canine model of chronic horizontal alveolar ridge defect.

MATERIALS AND METHODS

The second, third and fourth lower premolars of both sides were extracted, and the buccal bone walls were completely removed in five beagle dogs. After 4 weeks, DBBM particles mixed with autogenous bone chips at a ratio of 1:1 were grafted at one side (DBBM/Auto group), while DBBM particles alone were grafted at the contralateral side (DBBM group). The graft materials on both sides were covered by a resorbable collagen membrane and fixation pins. Microcomputed tomographic volume and histomorphometric analyses were performed at 16 weeks post-surgery.

RESULTS

The ridges of both groups were recovered horizontally, but new bone formation beyond the original ridge contour at the defect site was not found. The DBBM group exhibited a larger total radiographic augmented volume and new bone volume compared with the DBBM/Auto group, but the differences were minimal (p > .05). Histologically, the regenerated area and new bone area were also slightly larger without any statistical significance in the DBBM group than in the DBBM/Auto group (p > .05).

CONCLUSION

The addition of autogenous bone chips to DBBM for lateral ridge augmentation may confer no advantage over grafting DBBM alone with respect to both space maintenance and de novo bone formation in dogs.

Individualized plasticity autograft mimic with efficient bioactivity inducing osteogenesis

Mineralized tissue regeneration is an important and challenging part of the field of tissue engineering and regeneration. At present, autograft harvest procedures may cause secondary trauma to patients, while bone scaffold materials lack osteogenic activity, resulting in a limited application. Loaded with osteogenic induction growth factor can improve the osteoinductive performance of bone graft, but the explosive release of growth factor may also cause side effects. In this study, we innovatively used platelet-rich fibrin (PRF)-modified bone scaffolds (Bio-Oss^®) to replace autograft, and used cytokine (BMP-2) to enhance osteogenesis. Encouragingly, this mixture, which we named “Autograft Mimic (AGM)”, has multiple functions and advantages. (1) The fiber network provided by PRF binds the entire bone scaffold together, thereby shaping the bone grafts and maintaining the space of the defect area. (2) The sustained release of BMP-2 from bone graft promoted bone regeneration continuously. (3) AGM recruited bone marrow mesenchymal stem cells (BMSCs) and promote their proliferation, migration, and osteogenic differentiation. Thus, AGM developed in this study can improve osteogenesis, and provide new guidance for the development of clinical bone grafts.

The Role of Custom-made Subperiosteal Implants for Rehabilitation of Atrophic Jaws - A Case Report

Rehabilitation of atrophic jaws with conventional endosseous implant-supported overdentures and immediate loading protocols still presents a challenge nowadays. Custom-made implants with immediate loading overdenture are emerging as a solution for atrophic jaws rehabilitation. The authors describe the case of a 44-year-old male with a history of congenital dental agenesis. A previous oral rehabilitation with an all-on-6 type, implant-fixed mandibular overdenture, had failed due to peri-implantitis. The patient was successfully treated with bimaxillary custom-made subperiosteal implants with an innovative design, combining subperiosteal and endosseous support. The authors consider custom-made subperiosteal implants, in selected patients, present several advantages over classic bone-grafting plus endosseous implant-placement techniques such as (1) possibility of a single-stage procedure with immediate loading in atrophic jaws; (2) possible primary option to approach atrophic jaws as a simpler and less time-consuming technique; and (3) a valid rescue option for failed endosseous implants. More long-term studies with large samples of patients will be necessary to confirm previous assumptions.

MRI for the display of autologous onlay bone grafts during early healing-an experimental study

OBJECTIVES

Autologous bone grafts are the gold standard to augment deficient alveolar bone. Dimensional graft alterations during healing are not known as they are not accessible to radiography. Therefore, MRI was used to display autologous onlay bone grafts in vivo during early healing.

METHODS AND MATERIALS

Ten patients with alveolar bone atrophy and autologous onlay grafts were included. MRI was performed with a clinical MR system and an intraoral coil preoperatively (t0), 1 week (t1), 6 weeks (t2) and 12 weeks (t3) postoperatively, respectively. The graft volumes were assessed in MRI by manual segmentation by three examiners. Graft volumes for each time point were calculated and dimensional alteration was documented. Cortical and cancellous proportions of bone grafts were assessed. The intraobserver and interobserver variability were calculated. Statistical analysis was performed using a mixed linear regression model.

RESULTS

Autologous onlay bone grafts with cortical and cancellous properties were displayed in vivo in eight patients over 12 weeks. The fixation screws were visible as signal voids with a thin hyperintense fringe. The calculated volumes were between 0.12-0.74 cm³ (t1), 0.15-0.73 cm³ (t2), and 0.17-0.64 cm³ (t3). Median changes of bone graft volumes of -15% were observed. There was no significant difference between the examiners (p = 0.3).

CONCLUSIONS

MRI is eligible for the display and longitudinal observation of autologous onlay bone grafts. Image artifacts caused measurements deviations in some cases and minimized the precise assessment of graft volume. To the knowledge of the authors, this is the first study that used MRI for the longitudinal observation of autologous onlay bone grafts.

Intramedullary injury combined with osteoporosis therapeutics regulates targeted local osteogenesis

Bone marrow ablation prompts transient bone formation in nearly the entire medullary cavity before marrow regeneration occurs. Here, we establish a procedure to direct bone formation in a desired particular site within the medullary cavity for support of biomedical devices. Local intramedullary injury was performed in the tibiae of rats and parathyroid hormone (PTH), alendronate, or saline was administered. Newly generated bone in the medulla was assessed by micro-CT and histology. To evaluate the function of newly generated bone, animals received intramedullary injury in tibiae followed by daily PTH. At day-14, implants were placed in the endocortical bone and the bone response to the implants was assessed. The fate of newly generated bone was compared with and without implants. We found that neither intramedullary injury nor medication alone resulted in bone formation. However, when combined, substantial bone was generated locally inside the diaphyseal medulla. Newly formed bone disappeared without implant placement but was retained with implants. Bone was especially retained around and between the implants. This study found that local bone marrow disruption followed by PTH or alendronate generated substantial cancellous bone locally in the diaphyseal medulla. This approach offers promise as a tissue engineering tool in medicine and dentistry.

Digital Customized Titanium Mesh for Bone Regeneration of Vertical, Horizontal and Combined Defects: A Case Series

Background and Objective: Guided bone regeneration allows new bone formation in anatomical sites showing defects preventing implant rehabilitation. Material and Methods: The present case series reported the outcomes of five patients treated with customized titanium meshes manufactured with a digital workflow for achieving bone regeneration at future implant sites. A significant gain in both width and thickness was achieved for all patients. Results: From a radiographic point of view (CBTC), satisfactory results were reached both in horizontal and vertical defects. An average horizontal gain of 3.6 ± 0.8 mm and a vertical gain of 5.2 ± 1.1 mm. Conclusions: The findings from this study suggest that customized titanium meshes represent a valid method to pursue guided bone regeneration in horizontal, vertical or combined defects. Particular attention must be paid by the surgeon in the packaging of the flap according to a correct method called the "poncho" technique in order to reduce the most frequent complication that is the exposure of the mesh even if a partial exposure of one mesh does not compromise the final outcome of both the reconstruction and the healing of the implants.

Evaluation of Goose-beak Bone Particles for Dentoalveolar Reconstruction in Dogs

BACKGROUND/AIM

Tooth extraction is a common procedure in dental clinics. Tooth extraction can destroy gingiva, alveolar bone, periodontal ligaments and cement. If dental sockets are left as extracted, it will result in loss of teeth, as well as voice and aesthetic problems. A natural hydroxyapatite (HA) bioceramic bone graft substitute developed from goose-beak bone particles (GBPs) was used for dentoalveolar reconstruction in a canine model.

MATERIALS AND METHODS

Four adult (18-22 months old) male beagle dogs weighing 8.2-9.6 kg were included in the study. Eight alveolar extraction sockets in the four dogs were divided randomly into two groups and a split-mouth design was established; control group, socket filled with commercial synthetic HA; tested group, socket filled with granulated GBP.

RESULTS

Micro-CT analysis and hematoxylin and eosin and Masson's trichrome staining of non-decalcified sections were undertaken. Examination revealed that dentoalveolar reconstruction was initiated from the periphery of the host bone, and newly formed bone was well integrated with the GBP. Bone apposition was observed at the edge of the host bone-GBP interface.

CONCLUSION

A natural ceramic powder obtained from GBP is suitable for use in dentoalveolar reconstruction in dogs.

All-trans retinoic acid and human salivary histatin-1 promote the spreading and osteogenic activities of pre-osteoblasts in vitro

Cell‐based bone tissue engineering techniques utilize both osteogenic cells and biomedical materials, and have emerged as a promising approach for large‐volume bone repair. The success of such techniques is highly dependent on cell adhesion, spreading, and osteogenic activities. In this study, we investigated the effect of co‐administration of all‐trans retinoic acid (ATRA) and human salivary peptide histatin‐1 (Hst1) on the spreading and osteogenic activities of pre‐osteoblasts on bio‐inert glass surfaces. Pre‐osteoblasts (MC3T3‐E1 cell line) were seeded onto bio‐inert glass slides in the presence and absence of ATRA and Hst1. Cell spreading was scored by measuring surface areas of cellular filopodia and lamellipodia using a point‐counting method. The distribution of fluorogenic Hst1 within osteogenic cells was also analyzed. Furthermore, specific inhibitors of retinoic acid receptors α, β, and γ, such as ER‐50891, LE‐135, and MM‐11253, were added to identify the involvement of these receptors. Cell metabolic activity, DNA content, and alkaline phosphatase (ALP) activity were assessed to monitor their effects on osteogenic activities. Short‐term (2 h) co‐administration of 10 μm ATRA and Hst1 to pre‐osteoblasts resulted in significantly higher spreading of pre‐osteoblasts compared to ATRA or Hst1 alone. ER‐50891 and LE‐135 both nullified these effects of ATRA. Co‐administration of ATRA and Hst1 was associated with significantly higher metabolic activity, DNA content, and ALP activity than either ATRA or Hst1 alone. In conclusion, co‐administration of Hst1 with ATRA additively stimulated the spreading and osteogenicity of pre‐osteoblasts on bio‐inert glass surfaces in vitro.

Selection of Collagen Membranes for Bone Regeneration: A Literature Review

Several treatment modalities have been proposed to regenerate bone, including guided bone regeneration (GBR) where barrier membranes play an important role by isolating soft tissue and allowing bone to grow. Not all membranes biologically behave the same way, as they differ from their origin and structure, with reflections on their mechanical properties and on their clinical performance. Collagen membranes have been widely used in medicine and dentistry, because of their high biocompatibility and capability of promoting wound healing. Recently, collagen membranes have been applied in guided bone regeneration with comparable outcomes to non-resorbable membranes. Aim of this work is to provide a review on the main features, application, outcomes, and clinical employment of the different types of collagen membranes. Comparisons with non-resorbable membranes are clarified, characteristics of cross-linked collagen versus native collagen, use of different grafting materials and need for membrane fixation are explored in order to gain awareness of the indications and limits and to be able to choose the right membrane required by the clinical condition.

Osseous Healing in Surgically Prepared Bone Defects Using Different Grafting Materials: An Experimental Study in Pigs

Regeneration of large jaw bone defects still remains a clinical challenge. To avoid incomplete bone repair, bone grafts have been advocated to support the healing process. This study comparatively evaluated new bone formation among a synthetic graft substitute, a human bone derivative, and a bovine xenograft. Materials were placed in 3 out of the 4 bone cavities, while 1 deficit was left empty, serving as a control, in mono-cortical defects, surgically prepared in the porcine calvaria bone. Animals were randomized in 2 groups and euthanized at 8 and 12 weeks. Harvested tissue specimens were qualitatively evaluated by histology. New bone formation was quantitatively measured by histomorphometry. Maximum new bone formation was noticed in defects grafted with beta-tricalcium phosphate b-TCP compared to the other bone substitutes, at 8 and 12 weeks post-surgery. Bovine and human allograft induced less new bone formation compared to empty bone cavity. Histologic analysis revealed that b-TCP was absorbed and substituted significantly, while bovine and human allograft was maintained almost intact in close proximity with new bone. Based on our findings, higher new bone formation was detected in defects filled with b-TCP when compared to bovine and human graft substitutes.

Remodeling of calvarial graft in increased atrophic maxillary thickness. A prospective clinical study

PURPOSE

This study evaluated the autogenous graft resorption rate in a calvarial block graft in the anterior region of an atrophic maxilla and compared it with the thickness of the remaining ridge.

MATERIALS AND METHODS

Twelve patients were included in the study. They were submitted to cranial calotte graft surgery, and there were 40 blocks in total. The thicknesses of the ridges in the crest, middle and apical regions of the blocks were evaluated by computed tomography scan at the times: preoperative (T0), 48 hours (T1) and 6 months (T2) after the reconstructions.

RESULTS

The resorption of the blocks from T1 to T2 was 13.4%. The greatest remodeling occurred in the alveolar bone crest (20.07%), followed by the middle portion (12.28%), and the apical region (9.5%), but the three regions did not significantly differ between times T1 and T2 (crest P = .07, middle P = .124, apical P = .131). Recipient site with the lowest thickness had the greatest resorption rates (up to 2 mm = 17.6%; from 2 to 4 mm = 17.52%) while than those with a thickness greater than 4 mm had a mean resorption of 8.81%.

CONCLUSIONS

The resorption of the grafts in this study was 13.4%. Higher resorption rates were observed in the alveolar crest areas, where the ridges were less thick.

Bone grafting materials in dentoalveolar reconstruction: A comprehensive review

Bone deficits of the jaws are often attributed to accidents, surgical removal of benign lesions or malignant neoplasms, congenital abnormalities, periodontal inflammation, tooth abscess or extraction and finally jaw atrophy due to advanced age or general disease. These bone defects require rehabilitation for a variety of reasons, e.g. maintaining the normal anatomic outline, eliminating empty space, aesthetic restoration and placing dental implants. Today, several techniques have been developed to eliminate these bone deformities including bone grafting, guided bone regeneration, distraction osteogenesis, use of growth factors and stem cells. Bone grafts consist of materials of natural or synthetic origin, implanted into the bone defect site, documented to possess bone healing properties. Currently, a variety of bone restorative materials with different characteristics are available, possesing different properties. Despite years of effort the 'perfect' bone reconstruction material has not yet been developed, a further effort is required to make this objective feasible. The aim of this article is to provide a contemporary and comprehensive overview of the grafting materials that can be applied in dentoalveolar reconstruction, discussing their properties, advantages and disadvantages, enlightening the present and the future perspectives in the field of bone regeneration.

Long-term radiographic assessment of titanium implants installed in maxillary areas grafted with autogenous bone blocks using two predefined sets of success criteria

PURPOSE

Assess the radiographic peri-implant bone loss of implants installed in maxillary areas grafted with autogenous bone and classify the long-term (at least >4 ≤ 6 years) implant success according to two predefined sets of criteria.

MATERIAL AND METHODS

Sixty patients had full maxillary alveolar reconstructions using autogenous bone grafts (iliac crest), and 369 titanium implants were installed. The follow-up protocol was 5 (>4 ≤ 6) years; thereafter only patients who presented significant peri-implant bone loss were followed up to 12 years. The radiographic peri-implant bone level was assessed on panoramic radiographs in relation to the baseline and used to classify the long-term success of the implants according to the predefined success criteria presented by Albrektsson and coworkers (ALB; 1986) and the Pisa Consensus Conference (PCC; 2007).

RESULTS

Fifteen implants were lost over the 12-year follow-up period (two up to >4 ≤ 6 years). Mean radiographic peri-implant bone loss was 2.7 mm at the >4 ≤ 6 years control and 4.2 mm after >11 ≤ 12 years. Different success criteria resulted in different types of prevalence of implants classified as "failures." At >4 ≤ 6 years, 48% of the implants would be "failures" according to ALB, while according to the PCC, only 0.8% would be "failures" and 18.1% would be classified as "compromised survival" and 44.8% as "satisfactory survival."

CONCLUSIONS

Mean peri-implant bone loss of implants installed in maxillary areas grafted with autogenous bone blocks was 2.7 mm after >4 ≤ 6 years, and two implants were lost during this period. The use of different success criteria significantly altered the prevalence of implants classified as "failure."

Efficacy of a mineralized collagen bone-grafting material for peri-implant bone defect reconstruction in mini pigs

The mechanism of the mineralization process induced by natural mineralized collagen (MC) has been investigated for decades. The purpose of this study was to investigate the efficacy of self-assembled MC for peri-implant bone defect reconstruction in a mini pig. A standardized peri-implant bone defect model was created using 14 mini pig mandibles. Two materials were evaluated, i.e. a mixture of hydroxyapatite and collagen (Type A, TA), and self-assembled MC (Type B, TB). Bio-Oss (BO) and untreated (blank control, BC) groups were used as controls. After 3- and 6-month healing periods, the mini pigs were sacrificed for histomorphometric and microcomputed tomography analysis. After 3 months of healing, the average alveolar ridge height was 3.27 ± 1.57 mm for group TA, 3.28 ± 2.02 mm for group TB and 3.37 ± 1.09 mm for group BO, while group BC showed the lowest height of 2.68 ± 0.47 mm. After 6 months of healing, the average alveolar ridge height was 2.64 ± 1.13 mm for group TA, 4.31 ± 1.80 mm for group TB and 3.87 ± 1.38 mm for group BO, while group BC showed the lowest height of 2.48 ± 1.80 mm. The experimental groups and control group showed similar bone volume density, bone complexity and histological reaction. The self-assembled MC (Type B) stimulated new bone formation in the reconstruction of deficient alveolar ridges around the dental implant; it also displayed excellent clinical operability compared with bone grafts without collagen.

Lateral alveolar ridge augmentation procedure using subperiosteal tunneling technique: a pilot study

Background

In this research article, we evaluate the use of sub-periosteal tunneling (tunnel technique) combined with alloplastic in situ hardening biphasic calcium phosphate (BCP, a compound of β-tricalcium phosphate and hydroxyapatite) bone graft for lateral augmentation of a deficient alveolar ridge.

Methods

A total of 9 patients with deficient mandibular alveolar ridges were included in the present pilot study. Ten lateral ridge augmentation were carried out using the sub-periosteal tunneling technique, including a bilateral procedure in one patient. The increase in ridge width was assessed using CBCT evaluation of the ridge preoperatively and at 4 months postoperatively. Histological assessment of the quality of bone formation was also carried out with bone cores obtained at the implant placement re-entry in one patient.

Results

The mean bucco-lingual ridge width increased in average from 4.17 ± 0.99 mm to 8.56 ± 1.93 mm after lateral bone augmentation with easy-graft CRYSTAL using the tunneling technique. The gain in ridge width was statistically highly significant (p = 0.0019). Histomorphometric assessment of two bone cores obtained at the time of implant placement from one patient revealed 27.6% new bone and an overall mineralized fraction of 72.3% in the grafted area 4 months after the bone grafting was carried out.

Conclusions

Within the limits of this pilot study, it can be concluded that sub-periosteal tunneling technique using in situ hardening biphasic calcium phosphate is a valuable option for lateral ridge augmentation to allow implant placement in deficient alveolar ridges. Further prospective randomized clinical trials will be necessary to assess its performance in comparison to conventional ridge augmentation procedures.

Bone regeneration using three-dimensional hexahedron channel structured BCP block in rabbit calvarial defects

The purpose of this study is to evaluate the efficacy of bone regeneration and volume maintenance of the three-dimensional (3D) structured biphasic calcium phosphate (BCP) block with porous hexahedron channels in a rabbit calvarial model. In this work, four circular defects (diameter: 8 mm) in calvarium of rabbits were randomly assigned to (1) negative control (control), (2) 3D hexahedron channel structured BCP block, (3) deproteinized bovine bone mineral particle, and (4) deproteinized porcine bone mineral particle. Animals were euthanized at 2 (n = 5) and 8 weeks (n = 5). Outcome measures included micro-computed tomography (CT) and histomorphometrical analysis. Results indicated that in micro-CT, BCP group showed the highest new bone volume with significant difference compared to control (p = 0.008) at 8 weeks. Histomorphometrically, total augmented area of BCP group was the highest with significant difference compared to control (p = 0.008) at 8 weeks. BCP group also maintained total volume of the original defect without collapsing. BCP block with 3D hexahedron channel structure seems to have favorable osteogenic and volume maintaining ability and highly porous structure might attribute to new bone formation. Further studies regarding the optimal internal structure and porosity of the BCP block bone substitute are needed. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2254-2262, 2019.

Long term follow-up of titanium implants installed in block-grafted areas: A systematic review

BACKGROUND

An enduring clinical question concerns the outcome (ie, success) of implants placed in areas grafted with block-grafts.

OBJECTIVE

To undertake a systematic review of the literature on the long term results (≥5 years) of implants placed in maxillofacial areas grafted with any type of osseous block-grafts in two-stage surgeries. Further, the review addresses how available success criteria were used within the studies.

MATERIALS AND METHODS

The MEDLINE (PubMed) and EMBASE bibliographic databases were searched up to March 2017 for studies evaluating the long term results of implants placed in grafted areas. The search strategy was restricted to English language publications using combined terms which referred to the treatment method (implants placed in areas grafted with bone blocks), and follow-up characteristics (≥5 years and assessment of at least one parameter related to implant success criteria). To qualify for inclusion, studies should present outcome measurements indicating the success (or at least the survival) of the implants.

RESULTS

The search strategy yielded 17 studies, which were included in this systematic review. These studies presented survival rates ranging from 88.7% (after 15 years follow-up) to 98.7% (after 5 years follow-up). Five studies presented data based on predefined success criteria with success rates ranging from 86.8% to 100%. In these studies, the term "success" was often not properly defined.

CONCLUSION

The long term survival (≥5 years) of implants placed into block-grafted areas in two-stage surgeries was not lower than 75%, while success rates ranged from 86.8% to 100%. Although it was possible to identify published success criteria for implant follow-up, there is no broad consensus on how to report implant success in a consistent manner.

GBR membrane of novel poly (butylene succinate-co-glycolate) co-polyester co-polymer for periodontal application

In periodontics, osteoconductive biodegradable guided bone regeneration (GBR) membranes with acceptable physico-mechanical properties are required to fix alveolar bone defects. The objectives of the present study were to produce and characterize a novel co-polyester—poly (butylene succinate-co-glycolate) (PBSGL), and fabricate a PBSGL membrane by electrospinning. We then aimed to evaluate the in vitro effect of the glycolate ratio on the biocompatibility and osteogenic differentiation of mesenchymal stem cells (MSCs), and evaluate in vivo bone regeneration using these membranes in rabbit calvarial defects by histology. Increasing the glycolate ratio of electrospun PBSGL membranes resulted in better cell attachment, greater cell metabolic activity, and enhanced osteogenic potential at both transcriptional and translational levels. Histologic and histomorphometric evaluations revealed further that bone defects covered with fibers of higher glycolate ratios showed more bone formation, with no adverse inflammatory response. These results suggest that novel PBSGL electrospun nanofibers show great promise as GBR membranes for bone regeneration.

Localized ridge augmentation in the anterior maxilla using titanium mesh, an alloplast, and a nano-bone graft: a case report

Alveolar ridge deficiency is considered a major limitation for successful implant placement, as well as for the long-term success rate, especially in the anterior maxillary region. Various approaches have been developed to increase bone volume. Among those approaches, inlay and onlay grafts, alveolar ridge distraction, and guided bone regeneration have been suggested. The use of titanium mesh is a reliable method for ridge augmentation. We describe a patient who presented with a localized, combined, horizontal and vertical ridge defect in the anterior maxilla. The patient was treated using titanium mesh and alloplast material mixed with a nano-bone graft to treat the localized ridge deformity for future implant installation. The clinical and radiographic presentation, as well as relevant literature, are presented.

Degradation pattern of a porcine collagen membrane in an in vivo model of guided bone regeneration

BACKGROUND AND OBJECTIVE

Although collagen membranes have been clinically applied for guided tissue/bone regeneration for more than 30 years, their in vivo degradation pattern has never been fully clarified. A better understanding of the different stages of in vivo degradation of collagen membranes is extremely important, considering that the biology of bone regeneration requires the presence of a stable and cell/tissue-occlusive barrier during the healing stages in order to ensure a predictable result. Therefore, the aim of this study was to investigate the degradation pattern of a porcine non-cross-linked collagen membrane in an in vivo model of guided bone regeneration (GBR).

MATERIAL AND METHODS

Decalcified and paraffin-embedded specimens from calvarial defects of 18, 10-month-old Wistar rats were used. The defects were treated with a double layer of collagen membrane and a deproteinized bovine bone mineral particulate graft. At 7, 14 and 30 days of healing, qualitative evaluation with scanning electron microscopy and atomic force microscopy, and histomorphometric measurements were performed. Markers of collagenase activity and bone formation were investigated using an immunofluorescence technique.

RESULTS

A significant reduction of membrane thickness was observed from 7 to 30 days of healing, which was associated with progressive loss of collagen alignment, increased collagen remodeling and progressive invasion of woven bone inside the membranes. A limited inflammatory infiltrate was observed at all time points of healing.

CONCLUSION

The collagen membrane investigated was biocompatible and able to promote bone regeneration. However, pronounced signs of degradation were observed starting from day 30. Since successful regeneration is obtained only when cell occlusion and space maintenance exist for the healing time needed by the bone progenitor cells to repopulate the defect, the suitability of collagen membranes in cases where long-lasting barriers are needed needs to be further reviewed.

Tentpole technique for bone regeneration in vertically deficient alveolar ridges: A prospective study

Purpose

The purpose of the study was to qualitatively and quantitatively assess bone regeneration potential of tentpole technique using beta tricalcium phosphate bone graft in vertically deficient alveolar ridges.

Materials and Method

This prospective study comprised of 20 patients with vertically deficient alveolar ridges, wherein thirty one implants were placed. Tenting of the soft tissue matrix was done using titanium screws and beta tricalcium phosphate synthetic bone graft was filled in the vertical defect. Clinical and radiographic assessment was done at 1, 3 and 6 months. Preoperative biochemical analysis of Osteopontin and RANKL was done and then reassesed at 3 months postoperative. Bone core collected at 6 postoperative months, while removal of screw, was analysed histologically.

Results

A significant gain in bone height of 2.87 ± 0.79 mm was seen at 6 months postoperative. All implants osseointegrated. Loosening of screw was seen in two patients.There was no postoperative wound dehiscence. Histologic analysis revealed new bone formation .There was no significant change in the levels of RANKL and Osteopontin at 3 months postoperative.

Conclusion

This is a safe and effective technique for bone regeneration in vertically deficient alveolar ridges and has minimal complications. The regenerated bone has new and viable bone content and supports implant material. More studies with long term follow up are needed to assess the stability of bone after long term loading.

Control of dental-derived induced pluripotent stem cells through modified surfaces for dental application

OBJECTIVE

The aim of this study is to investigate the behaviour of iPSc derived from dental stem cells in terms of initial adhesion, differentiation potential on differently surface-treated titanium disc.

MATERIALS AND METHODS

iPSc derived from human gingival fibroblasts (hGFs) were established using 4-reprogramming factors transduction with Sendai virus. The hGF-iPSc established in this study exhibited the morphology and growth properties similar to human embryonic stem (ES) cells and expressed pluripotency makers. Alkaline Phosphatase (AP) staining, Embryoid Body (EB) formation and in vitro differentiation and karyotyping further confirmed pluripotency of hGF-iPSc. Then, hGF-iPSc were cultured on machined- and Sandblasted and acid etched (SLA)-treated titanium discs with osteogenic induction medium and their morphological as well as quantitative changes according to different surface types were investigated using Alizrin Red S staining, Scanning electron microscopy (SEM), Flow cytometry and RT-PCR.

RESULTS

Time-dependent and surface-dependent morphological changes as well as quantitative change in osteogenic differentiation of hGF-iPSc were identified and osteogenic gene expression of hGF-iPSc cultured on SLA-treated titanium disc found to be greater than machined titanium disc, suggesting the fate of hGF-iPSc may be determined by the characteristics of surface to which hGF-iPSc first adhere.

CONCLUSIONS

iPSc derived from dental stem cell can be one of the most promising and practical cell sources for personalized regenerative dentistry and their morphological change as well as quantitative change in osteogenic differentiation according to different surface types may be further utilized for future clinical application incorporated with dental implant.

Translational Research for Injectable Tissue-Engineered Bone Regeneration Using Mesenchymal Stem Cells and Platelet-Rich Plasma: From Basic Research to Clinical Case Study

Translational research involves application of basic scientific discoveries into clinically germane findings and, simultaneously, the generation of scientific questions based on clinical observations. At first, as basic research we investigated tissue-engineered bone regeneration using mesenchymal stem cells (MSCs) and platelet-rich plasma (PRP) in a dog mandible model. We also confirmed the correlation between osseointegration in dental implants and the injectable bone. Bone defects made with a trephine bar were implanted with graft materials as follows: PRP, dog MSCs (dMSCs) and PRP, autogenous particulate cancellous bone and marrow (PCBM), and control (defect only). Two months later, dental implants were installed. According to the histological and histomorphometric observations at 2 months after implants, the amount of bone–implant contact at the bone–implant interface was significantly different between the PRP, PCBM, dMSCs/PRP, native bone, and control groups. Significant differences were also found between the dMSCs/PRP, native bone, and control groups in bone density. These findings indicate that the use of a mixture of dMSCs/PRP will provide good results in implant treatment compared with that achieved by autogenous PCBM. We then applied this injectable tissue-engineered bone to onlay plasty in the posterior maxilla or mandible in three human patients. Injectable tissue-engineered bone was grafted and, simultaneously, 2–3 threaded titanium implants were inserted into the defect area. The results of this investigation indicated that injectable tissue-engineered bone used for the plasty area with simultaneous implant placement provided stable and predictable results in terms of implant success. We regenerated bone with minimal invasiveness and good plasticity, which could provide a clinical alternative to autogenous bone grafts. This might be a good case of translational research from basic research to clinical application.

Development of a synthetic tissue engineered three-dimensional printed bioceramic-based bone graft with homogenously distributed osteoblasts and mineralizing bone matrix in vitro

Over the last decade there have been increasing efforts to develop three-dimensional (3D) scaffolds for bone tissue engineering from bioactive ceramics with 3D printing emerging as a promising technology. The overall objective of the present study was to generate a tissue engineered synthetic bone graft with homogenously distributed osteoblasts and mineralizing bone matrix in vitro, thereby mimicking the advantageous properties of autogenous bone grafts and facilitating usage for reconstructing segmental discontinuity defects in vivo. To this end, 3D scaffolds were developed from a silica-containing calcium alkali orthophosphate, using, first, a replica technique - the Schwartzwalder-Somers method - and, second, 3D printing, (i.e. rapid prototyping). The mechanical and physical scaffold properties and their potential to facilitate homogenous colonization by osteogenic cells and extracellular bone matrix formation throughout the porous scaffold architecture were examined. Osteoblastic cells were dynamically cultured for 7 days on both scaffold types with two different concentrations of 1.5 and 3 × 10⁹ cells/l. The amount of cells and bone matrix formed and osteogenic marker expression were evaluated using hard tissue histology, immunohistochemical and histomorphometric analysis. 3D-printed scaffolds (RPS) exhibited more micropores, greater compressive strength and silica release. RPS seeded with 3 × 10⁹ cells/l displayed greatest cell and extracellular matrix formation, mineralization and osteocalcin expression. In conclusion, RPS displayed superior mechanical and biological properties and facilitated generating a tissue engineered synthetic bone graft in vitro, which mimics the advantageous properties of autogenous bone grafts, by containing homogenously distributed terminally differentiated osteoblasts and mineralizing bone matrix and therefore is suitable for subsequent in vivo implantation for regenerating segmental discontinuity bone defects. Copyright © 2016 John Wiley & Sons, Ltd.

Natural graft tissues and synthetic biomaterials for periodontal and alveolar bone reconstructive applications: a review

Periodontal disease is categorized by the destruction of periodontal tissues. Over the years, there have been several clinical techniques and material options that been investigated for periodontal defect repair/regeneration. The development of improved biomaterials for periodontal tissue engineering has significantly improved the available treatment options and their clinical results. Bone replacement graft materials, barrier membranes, various growth factors and combination of these have been used. The available bone tissue replacement materials commonly used include autografts, allografts, xenografts and alloplasts. These graft materials mostly function as osteogenic, osteoinductive and/or osteoconductive scaffolds. Polymers (natural and synthetic) are more widely used as a barrier material in guided tissue regeneration (GTR) and guided bone regeneration (GBR) applications. They work on the principle of epithelial cell exclusion to allow periodontal ligament and alveolar bone cells to repopulate the defect before the normally faster epithelial cells. However, in an attempt to overcome complications related to the epithelial down-growth and/or collapse of the non-rigid barrier membrane and to maintain space, clinicians commonly use a combination of membranes with hard tissue grafts. This article aims to review various available natural tissues and biomaterial based bone replacement graft and membrane options used in periodontal regeneration applications.

Retrospective long-term analysis of bone level changes after horizontal alveolar crest reconstruction with autologous bone grafts harvested from the posterior region of the mandible

Purpose

The goal of this study was to evaluate the long-term success of horizontal alveolar crest augmentation of the retromolar region of the mandible with particulated bone, as well as factors affecting subsequent peri-implant bone loss.

Methods

A total of 109 patients (68 female, 41 male) suffering from alveolar ridge deficiencies of the maxilla and mandible were included in this study. All patients were treated with particulated retromolar bone grafts from the mandible prior to the insertion of endosseous dental implants. Mesial and distal peri-implant crestal bone changes were assessed at six time points. Several parameters, including implant survival and the influence of age, gender, localisation of the implant, diameter, covering procedures, and time points of implant placement, were analysed to identify associations with bone level changes using the Mann-Whitney U-test, the Kruskal-Wallis test, and Spearman's rank-order correlation coefficient.

Results

A total of 164 dental implants were placed in the maxilla (n=97) and in the mandible (n=67). The mean observation period was 105.26±21.58 months after implantation. The overall survival rate was 97.6% after 10 years. Overall, peri-implant bone loss was highest during the first year, but decreased over time. The mean amount of bone loss after 10 years was 2.47 mm mesially and 2.50 mm distally. Bone loss was significantly influenced by implant type and primary stability.

Conclusions

The use of particulated autologous retromolar bone grafts is a reliable technique for the horizontal reconstruction of local alveolar ridge deficiencies. Our results demonstrate that implants placed in augmented bone demonstrated similar bone level changes compared to implants inserted in non-augmented regions.

Histomorphometric evaluation of onlay freeze-dried block bone and deproteinized bovine bone with collagen in rat

The aim of this study was to evaluate the effect of human freeze-dried bone block (FDBB) and deproteinized bovine bone with collagen (DBBC) on bone formation when applied as an onlay graft in rat calvariums. Thirty male Sprague-Dawley rats received collagen sponge (control), FDBB, or DBBC onlay grafts trimmed into 8-mm disks measuring 4-mm height. Each graft was secured onto the calvarium surface using horizontal mattress sutures. Rats in each group were killed at 2 (n=5) or 8 (n=5) weeks postoperatively for histologic and histomorphometric analysis. The total augmented area (mm²), new bone area (mm²), and bone density (%) were measured. The FDBB and DBBC groups showed significantly more new bone formation and bone density than the control group at 2 and 8 weeks. The increased new bone area was significantly greater in the FDBB group than in the DBBC group (p<0.05). The total augmented area was significantly higher in the FDBB and DBBC groups at 2 and 8 weeks than in the control group (p<0.05), and at 8 weeks, the area was significantly decreased in the DBBC group compared to that in the FDBB group and the area at 2 weeks (p<0.05). Within the limitations of the present study, we concluded that onlay FDBB and DBBC grafts caused new bone formation through an osteoconductive mechanism. In addition, compared to FDBB, DBBC had less capacity to form new bone and maintain the space.

Periimplant bone regeneration in hydroxyapatite block grafts with mesenchymal stem cells and bone morphogenetic protein-2

Hydroxyapatite (HA) blocks as an alternative material for autogenous onlay bone grafts are regarded as an insufficient substitute for osseointegration of dental implant. In this study, we evaluated the effects of dog mesenchymal stromal cells (dMSCs) with or without bone morphogenetic protein-2 (BMP) on new peri-implant bone formation after HA block graft. In four mandibular bone defects (8×8×6 mm each) in five beagle dogs, dental implants were placed with HA block loaded with autogenous dMSCs with or without BMP-2. Animals were sacrificed at eight weeks, and bone healing was evaluated among four groups consisting of 1) HA alone as a control, 2) HA+dMSCs, 3) HA+BMP-2, and 4) HA+dMSCs+BMP-2. According to histomorphometric evaluation, the MSC+BMP-2 group and the BMP-2 group showed significantly higher bone-implant-contact (BIC) length than the MSC group, while there was no significant difference in new bone formation among the groups. According to micro-CT analysis, bone volume and bone mineral density were significantly higher in the MSC+BMP-2 group compared with the control group (p<0.01 and p<0.05, respectively). BIC was significantly higher in the MSC+BMP-2 group than both the control and MSC groups (p<0.01 and p<0.05, respectively). In conclusion, our results showed that bone regeneration at peri-implant bone defects grafted with HA blocks was significantly increased by dual delivery of MSCs and BMP-2. Conversely, HA blocks with MSC or BMP-2 alone did not allow for efficient peri-implant bone regeneration.

Secondary closure of alveolar cleft with resorbable collagen membrane and a combination of intraoral autogenous bone graft and deproteinized anorganic bovine bone

OBJECTS

Secondary alveolar bone grafting is a method that enables an excellent oral rehabilitation of the patients having alveolar cleft. The aim of this work is to report the closure of the alveolar cleft with the use of harvested autogenous bone graft combined with deproteinized anorganic bovine bone (Bio-Oss) under local anesthesia.

SETTINGS AND SAMPLE POPULATION

Nine patients with age range, 8-11 years were consulted for their unilateral alveolar cleft.

MATERIALS AND METHODS

A combination of symphyseal bone and deproteinized bovine bone mineral (DBBM) was placed into the alveolar cleft defect. Clinical and radiographical assessments were performed at 1, 3, and 6 months postoperatively.

RESULTS

The healing period was uneventful in all cases, and no complications, such as membrane exposure, infection, or harvest site morbidity, were observed. All treated defect sites exhibited excellent bone formation, with an average of 5.45 mm (range, 2-9 mm; standard deviation 1.93 mm) of augmentation achieved overall.

CONCLUSION

The treatment of vertically deficient alveolar ridges with guided bone regeneration using a mixture of autogenous bone and DBBM and resorbable collagen membrane can be considered successful, using this technique in an out-patient office setting.