Bioinspired Piezoelectric Periosteum to Augment Bone Regeneration via Synergistic Immunomodulation and Osteogenesis.

Ideal periosteum materials are required to participate in a sequence of bone repair-related physiological events, including the initial immune response, endogenous stem cell recruitment, angiogenesis, and osteogenesis. However, conventional tissue-engineered periosteal materials have difficulty achieving these functions by simply mimicking the periosteum via structural design or by loading exogenous stem cells, cytokines, or growth factors. Herein, we present a novel biomimetic periosteum preparation strategy to comprehensively enhance the bone regeneration effect using functionalized piezoelectric materials. The resulting biomimetic periosteum possessing an excellent piezoelectric effect and improved physicochemical properties was prepared using a biocompatible and biodegradable poly(3-hydroxybutyric acid-co-3-hydrovaleric acid) (PHBV) polymer matrix, antioxidized polydopamine-modified hydroxyapatite (PHA), and barium titanate (PBT), which were further incorporated into the polymer matrix to fabricate a multifunctional piezoelectric periosteum by a simple one-step spin-coating method. The addition of PHA and PBT dramatically enhanced the physicochemical properties and biological functions of the piezoelectric periosteum, resulting in improved surface hydrophilicity and roughness, enhanced mechanical performance, tunable degradation behavior, and stable and desired endogenous electrical stimulations, which is conducive to accelerating bone regeneration. Benefiting from endogenous piezoelectric stimulation and bioactive components, the as-fabricated biomimetic periosteum demonstrated favorable biocompatibility, osteogenic activity, and immunomodulatory functions in vitro, which not only promoted adhesion, proliferation, and spreading as well as osteogenesis of mesenchymal stem cells (MSCs) but also effectively induced M2 macrophage polarization, thereby suppressing reactive oxygen species (ROS)-induced inflammatory reactions. Through in vivo experiments, the biomimetic periosteum with endogenous piezoelectric stimulation synergistically accelerated the formation of new bone in a rat critical-sized cranial defect model. The whole defect was almost completely covered by new bone at 8 weeks post treatment, with a thickness close to that of the host bone. Collectively, with its favorable immunomodulatory and osteogenic properties, the biomimetic periosteum developed here represents a novel method to rapidly regenerate bone tissue using piezoelectric stimulation.

Mastoid obliteration and canal wall reconstruction with posterior auricular artery (PAA) fascia-periosteum flap.

OBJECTIVE: Unstable cavities are defined as cavities with cerumen accumulation that need frequent cavity cleaning in the out-patient clinic, cavities that are intolerant to water due to risk of infection or that are subject to frequent infection and otorrhoea. The objective of this study is to address the problem of troublesome mastoid cavities, with the performance of secondary mastoid obliteration and canal wall reconstruction, using a novel posterior auricular artery (PAA) fascia-periosteum flap. MATERIALS AND METHODS: A prospective study was designed, only secondary obliterations were included. Unstable mastoid cavities were defined as Merchant grade 2 or 3 and were included for surgery. RESULTS: At 12 months of follow up, a complete external auditory canal (EAC) and a self-cleaning ear were achieved in all 23 patients. Completely dry ears were achieved in 21 patients (91.3%). An air-bone gap improvement of 5dB was achieved. CONCLUSION: Mastoid obliteration and EAC reconstruction are effective procedures to treat troublesome post canal wall down mastoid cavities. They improve quality of life and enable patients to overcome ear discharge. A standard EAC size enables the utilization of conventional hearing aids, it also reduces the need for constant mastoid cleaning and decreases healthcare expenses. The PAA flap seems to be an effective procedure to achieve all these features, as it is used to obliterate the mastoid and becomes a structural component of the neo-EAC.

Insertion sites of the muscles attached to the clavicle: a cadaveric study of the clavicle.

BACKGROUND: Clavicle fractures are common injuries, especially in young, active individuals. Operative treatment is recommended for completely displaced clavicle shaft fractures, and plate fixation is stronger than the use of intramedullary nails. Few studies have reported on iatrogenic injuries to the muscle attached to the clavicle during fracture surgery. The aim of this study was to clarify the area of the insertion sites of muscles attached to the clavicle in Japanese cadavers using gross anatomy and three-dimensional (3D) analysis. We also aimed to compare the effects of anterior plate templating and superior plate templating on clavicle shaft fractures using 3D images. METHODS: Thirty-eight clavicles from Japanese cadavers were analyzed. We removed all clavicles to identify the insertion sites and measured the size of the insertion area of each muscle. Three-dimensional templating was performed on both the superior and anterior plates of the clavicle using data obtained from computed tomography. The areas covered by these plates on the muscles attached to the clavicle were compared. Histological examination was performed on four randomly selected specimens. RESULTS: The sternocleidomastoid muscle was attached proximally and superiorly; the trapezius muscle was attached posteriorly and partly superiorly; and the pectoralis major muscle and deltoid muscles were attached anteriorly and partially superiorly. The non-attachment area was located mainly in the posterosuperior part of the clavicle. It was difficult to distinguish the borders of the periosteum and pectoralis major muscles. The anterior plate covered a significantly broader area (mean 6.94 ± 1.36 cm2) of the muscles attached to the clavicle than did the superior plate (mean 4.11 ± 1.52 cm2) (p < 0.0001). On microscopy, these muscles were inserted directly into the periosteum. CONCLUSION: Most of the pectoralis major and deltoid muscles were attached anteriorly. The non-attachment area was located mainly from the superior to posterior part of the clavicle midshaft. Both macroscopically and microscopically, the boundaries between the periosteum and these muscles were difficult to demarcate. The anterior plate covered a significantly broader area of the muscles attached to the clavicle than that by the superior plate.

Role of periosteum in alveolar bone regeneration comparing with collagen membrane in a buccal dehiscence model of dogs.

To investigate the role of periosteum on the treatment of buccal dehiscence defects comparing with collagen membrane in canine model. Bilateral dehiscence-type defects at the buccal side on the distal root of the lower 3rd/4th premolars were created in six beagle dogs with a total of 24 defects and assigned into three groups: Group A: blood clot in an untreated defect; Group B: deproteinized bovine bone material (DBBM) covered with an absorbable membrane; Group C: DBBM covered with the periosteum. The structural parameters for trabecular architecture and vertical bone regeneration were evaluated. Histological and histomorphometric evaluation were carried out to observe new bone formation and mineralization in the graft site. Immunohistochemical analysis was performed to identify the expression of osteopontin (OPN) and osteocalcin (OCN) at postoperative 3 months. Group C achieved greater vertical alveolar bone gain than that of group A and group B. The periosteum-covered group showed significantly greater new bone formation and accelerated mineralization. The greater immunolabeling for OPN and OCN was observed in group C than in group A. Periosteal coverage has explicit advantages over collagen membranes for the quality and quantity of new bone regeneration in dehiscence defects repairing.

Intermediate-term Outcomes in Adolescent Recurrent Ankle Instability Managed With a Modified Broström-Gould Procedure Augmented With Distal Fibular Periosteum Incorporation.

BACKGROUND: Once a child has developed chronic ankle instability with recurrent events despite conservative treatment, then ligamentous repair is warranted. We utilize a modification of the modified Broström-Gould technique that further incorporates the distal fibular periosteum into the construct. The purpose of this study was to describe the intermediate-term outcomes of our modified Broström-Gould technique for chronic lateral ankle instability in childhood athletes. METHODS: A retrospective review of children who underwent the surgical technique over a 10-year time period (2010 to 2019) was performed, excluding those with <2 years of follow-up. Demographic, surgical, and clinical data were recorded, as well as outcome scores: (1) the Marx activity scale, (2) University of California, Los Angeles activity score, and (3) foot and ankle outcomes score. Recurrent instability events, repeat surgeries, satisfaction with the surgical experience, and return to sport (if applicable) were also recorded. RESULTS: Forty-six children (43 females) with 1 bilateral ankle met the criteria with a mean age at surgery of 14.8 years, and a mean follow-up duration of 4.9 years. The mean Marx activity score was 9.0±5.1, the mean University of California, Los Angeles score was 8.3±1.8, and the mean total foot and ankle outcomes score was 84.0±15.6. Twenty-six ankles (55.3%) reported having at least 1 recurrent episode of instability and 6 of the ankles (12.8%) underwent revision surgery between 3.5 months and 6.5 years of the index procedure. Thirty-nine (84.8%) patients responded that they would undergo our surgery again. CONCLUSION: A modified Broström-Gould procedure can be performed in children with the incorporation of the adjacent periosteum, but recurrence of instability is distinctly possible with longer follow-up with a risk for revision surgery despite good subjective outcomes. LEVEL OF EVIDENCE: Level IV; retrospective case series.

Periosteal Bone Formation Varies with Age in Periostin Null Mice.

Periostin, also known as osteoblast-specific factor 2, is a matricellular protein predominantly expressed at the periosteum of bone. During growth and development, periostin contributes to periosteal expansion by facilitating osteoblast differentiation and mineralization. Later in life, periosteal expansion provides an adaptive strategy to increase tissue strength without requiring substantial increase in bone mass. However, the function of periostin past skeletal maturity and during advanced aging is relatively unknown. The objective of this study was to examine the function of periostin in maintaining bone mass and tissue strength across different ages. In periostin null mice (Postn-/-), periosteal bone formation was significantly reduced in young (3 months) and adult mice (9 months). The lack of bone formation resulted in reduced bone mass and ultimate strength. Conversely, periosteal bone formation increased at advanced ages in 18-month-old Postn-/- mice. The increase in periosteal mineralization at advanced ages coincides with increased expression of vitronectin and osteopontin. Periosteal progenitors from Postn-/- mice displayed an increased capacity to mineralize when cultured on vitronectin, but not type-1 collagen. Altogether, these findings demonstrate the unique role of periostin in regulating periosteal bone formation at different ages and the potential for vitronectin to compensate in the absence of periostin.

Continuous dynamic identification of key genes and molecular signaling pathways of periosteum in guided bone self-generation in swine model.

BACKGROUND: Guided bone self-generation with periosteum-preserved has successfully regenerated mandibular, temporomandibular and interphalangeal joint. The aim of this study was to investigate the dynamic changes of gene expression of periosteum which was involved in the guided bone self-generation. METHODS: Rib defects of critical size were created in mature swine with periosteum-preserved. The periosteum was sutured into a sealed sheath that closed the bone defect. The periosteum of trauma and control sites were harvested at postoperative 9 time points, and total RNA was extracted. Microarray analysis was conducted to identify the differences in the transcriptome of different time points between two groups. RESULTS: The differentially expressed genes (DEGs) between control and trauma group were different at postoperative different time points. The dynamic changes of the number of DEGs fluctuated a lot. There were 3 volatility peaks, and we chose 3 time points of DEG number peak (1 week, 5 weeks and 6 months) to study the functions of DEGs. Oxidoreductase activity, oxidation-reduction process and mitochondrion are the most enriched terms of Go analysis. The major signaling pathways of DEGs enrichment include oxidative phosphorylation, PI3K-Akt signaling pathway, osteoclast differentiation pathway and Wnt signaling. CONCLUSIONS: The oxidoreductase reaction was activated during this bone regeneration process. The oxidative phosphorylation, PI3K-Akt signaling pathway, osteoclast differentiation pathway and Wnt signaling may play important roles in the guided bone self-generation with periosteum-preserved. This study can provide a reference for how to improve the application of this concept of bone regeneration.

Three-dimensional bioprinted BMSCs-laden highly adhesive artificial periosteum containing gelatin-dopamine and graphene oxide nanosheets promoting bone defect repair.

The periosteum is a connective tissue membrane adhering to the surface of bone tissue that primarily provides nutrients and regulates osteogenesis during bone development and injury healing. However, building an artificial periosteum with good adhesion properties and satisfactory osteogenesis for bone defect repair remains a challenge, especially using three-dimensional (3D) bioprinting. In this study, dopamine was first grafted onto the molecular chain of gelatin usingN-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride andN-hydroxysuccinimide (NHS) to activate the carboxyl group and produce modified gelatin-dopamine (GelDA). Next, a methacrylated gelatin, methacrylated silk fibroin, GelDA, and graphene oxide nanosheet composite bioink loaded with bone marrow mesenchymal stem cells was prepared and used for bioprinting. The physicochemical properties, biocompatibility, and osteogenic roles of the bioink and 3D bioprinted artificial periosteum were then systematically evaluated. The results showed that the developed bioink showed good thermosensitivity and printability and could be used to build 3D bioprinted artificial periosteum with satisfactory cell viability and high adhesion. Finally, the 3D bioprinted artificial periosteum could effectively enhance osteogenesis bothin vitroandin vivo. Thus, the developed 3D bioprinted artificial periosteum can prompt new bone formation and provides a promising strategy for bone defect repair.

Wnt-associated adult stem cell marker Lgr6 is required for osteogenesis and fracture healing.

Despite the remarkable regenerative capacity of skeletal tissues, nonunion of bone and failure of fractures to heal properly presents a significant clinical concern. Stem and progenitor cells are present in bone and become activated following injury; thus, elucidating mechanisms that promote adult stem cell-mediated healing is important. Wnt-associated adult stem marker Lgr6 is implicated in the regeneration of tissues with well-defined stem cell niches in stem cell-reliant organs. Here, we demonstrate that Lgr6 is dynamically expressed in osteoprogenitors in response to fracture injury. We used an Lgr6-null mouse model and found that Lgr6 expression is necessary for maintaining bone volume and efficient postnatal bone regeneration in adult mice. Skeletal progenitors isolated from Lgr6-null mice have reduced colony-forming potential and reduced osteogenic differentiation capacity due to attenuated cWnt signaling. Lgr6-null mice consist of a lower proportion of self-renewing stem cells. In response to fracture injury, Lgr6-null mice have a deficiency in the proliferation of periosteal progenitors and reduced ALP activity. Further, analysis of the bone regeneration phase and remodeling phase of fracture healing in Lgr6-null mice showed impaired endochondral ossification and decreased mineralization. We propose that in contrast to not being required for successful skeletal development, Lgr6-positive cells have a direct role in endochondral bone repair.

Periosteal Pathologic Conditions: Imaging Findings and Pathophysiology.

The periosteum plays a key role in bone health and is a primary means by which the skeleton responds to a wide range of insults, both benign and malignant. Developmental and histologic features of normal periosteum explain some of the characteristic imaging findings seen in the setting of bone abnormalities. Patterns of periosteal reaction, both in morphology and distribution, are key to distinguishing benign or physiologic periosteal reaction from types of periosteal reaction that warrant further evaluation. The authors review the histologic features, distribution, and development of normal periosteum. Nonaggressive and aggressive types of periosteal reaction are presented with key associations for each. The presence of nonaggressive types of periosteal reaction implies that the underlying process affecting the bone is slow enough that the periosteum is able to heal it or contain it in an organized manner. In contrast, aggressive types of periosteal reaction are seen when the underlying bone insult outpaces the ability of the periosteum to contain it. Image-guided biopsies of lesions with periosteal reaction should be used to sample the site of the most aggressive pattern, as this approach can aid in accurate histologic grading and in detection of tumor cells and bone matrix. The distribution of periosteal abnormalities is as important as the morphology, with a diffuse periosteal reaction favoring systemic causes such as rheumatologic, metabolic, and hematologic conditions compared with a more localized periosteal reaction. Important causes of localized and diffuse periosteal reaction are discussed in a systems-based format, with an emphasis on clinically important causes. © RSNA, 2022.

In Situ Biomimetic Mineralization of Bone-Like Hydroxyapatite in Hydrogel for the Acceleration of Bone Regeneration.

A critical-sized bone defect, which cannot be repaired through self-healing, is a major challenge in clinical therapeutics. The combination of biomimetic hydrogels and nano-hydroxyapatite (nano-HAP) is a promising way to solve this problem by constructing an osteogenic microenvironment. However, it is challenging to generate nano-HAP with a similar morphology and structure to that of natural bone, which limits the improvement of bone regeneration hydrogels. Inspired by our previous works on organic-inorganic cocross-linking, here, we built a strong organic-inorganic interaction by cross-linking periosteum-decellularized extracellular matrix and calcium phosphate oligomers, which ensured the in situ mineralization of bone-like nano-HAP in hydrogels. The resulting biomimetic osteogenic hydrogel (BOH) promotes bone mineralization, construction of immune microenvironment, and angiogenesis improvement in vitro. The BOH exhibited acceleration of osteogenesis in vivo, achieving large-sized bone defect regeneration and remodeling within 8 weeks, which is superior to many previously reported hydrogels. This study demonstrates the important role of bone-like nano-HAP in osteogenesis, which deepens the understanding of the design of biomaterials for hard tissue repair. The in situ mineralization of bone-like nano-HAP emphasizes the advantages of inorganic ionic oligomers in the construction of organic-inorganic interaction, which provides an alternative method for the preparation of advanced biomimetic materials.

Periosteum as a covering vascular flap in posterior mandibular augmentation: A retrospective cohort study.

OBJECTIVE: To analyze the impact of creating periosteal vascular flaps on the amount of bone augmentation following inlay bone grafting (IBG) and cortical autogenous tenting (CAT). MATERIALS AND METHODS: This was a retrospective cohort study enrolling a sample cohort of patients presented to a private clinic in 2015 and 2019 for posterior mandibular ridge augmentation before dental implant placement. The predictor variables were surgical methods: CAT vs. CAT in conjunction with periosteal flap (CATP) vs. IBG vs. IBG in conjunction with periosteal flap (IBGP). The primary outcome variables were supra bundle bone (SBB) superior to the inferior alveolar canal (ΔH) and crestal width difference (ΔW) at a 4-month follow-up. Appropriate statistics were computed at 0.05 significance level. RESULTS: A total of 29 cases (10 males and 19 females) with a mean age of 57.96±7.14 years were included. A total of 33 sites were augmented through CATP, 16 sites through IBGP, 33 sites through CAT, and 11 sites through IBG techniques. All patients healed uneventfully without permanent neurosensory changes, and adequate horizontal (ΔW:3.33±0.71 mm) and vertical (ΔH:5.10±2.04 mm) bone dimensions were restored that allowed implant placement. Using periosteal vascular flaps significantly increased bone augmentation in both vertical and horizontal dimensions (P < 0.01). CONCLUSION: Periosteal vascular flaps can increase the efficacy of mandibular augmentation techniques and decrease post-surgical complications.

Mechanical strain induces ex vivo expansion of periosteum.

Segmental bone defects present complex clinical challenges. Nonunion, malunion, and infection are common sequalae of autogenous bone grafts, allografts, and synthetic bone implants due to poor incorporation with the patient's bone. The current project explores the osteogenic properties of periosteum to facilitate graft incorporation. As tissue area is a natural limitation of autografting, mechanical strain was implemented to expand the periosteum. Freshly harvested, porcine periosteum was strained at 5 and 10% per day for 10 days with non-strained and free-floating samples serving as controls. Total tissue size, viability and histologic examination revealed that strain increased area to a maximum of 1.6-fold in the 10% daily strain. No change in tissue anatomy or viability via MTT or Ki67 staining and quantification was observed among groups. The osteogenic potential of the mechanical expanded periosteum was then examined in vivo. Human cancellous allografts were wrapped with 10% per day strained, fresh, free-floating, or no porcine periosteum and implanted subcutaneously into female, athymic mice. Tissue was collected at 8- and 16-weeks. Gene expression analysis revealed a significant increase in alkaline phosphatase and osteocalcin in the fresh periosteum group at 8-weeks post implantation compared to all other groups. Values among all groups were similar at week 16. Additionally, histological assessment with H&E and Masson-Goldner Trichrome staining showed that all periosteal groups outperformed the non-periosteal allograft, with fresh periosteum demonstrating the highest levels of new tissue mineralization at the periosteum-bone interface. Overall, mechanical expansion of the periosteum can provide increased area for segmental healing via autograft strategies, though further studies are needed to explore culture methodology to optimize osteogenic potential.

Drug-Loaded and Anisotropic Wood-Derived Hydrogel Periosteum with Super Antibacterial, Anti-Inflammatory, and Osteogenic Activities.

Current artificial periostea mainly focus on osteogenic activity but overlook structural and mechanical anisotropy, as well as the importance of antibacterial and anti-inflammatory properties. Here, inspired by the anisotropic structure of wood, the delignified wood (named white wood, WW) with a porous and highly oriented cellulose fiber skeleton was obtained, which was further filled with polyvinyl alcohol (PVA) hydrogel loaded with curcumin (Cur) and phytic acid (PA). The prepared wood-derived hydrogel composite membranes can not only exhibit an obvious anisotropic structure and good mechanical properties but also sustainably release loaded drugs to obtain long-term biological activities. Creatively, PA can effectively improve the bioavailability of Cur; more importantly, Cur and PA play an obvious synergistic effect in antibacterial, anti-inflammatory, and osteogenic activities. Compared with the wood-derived hydrogel composite membranes without drug loading, as well as loaded with Cur or PA only, these loaded with Cur and PA are significantly more conducive to inhibiting the growth of bacteria and inflammatory response and facilitating the adhesion, proliferation, and osteogenic differentiation of bone marrow mesenchymal stem cells. This kind of anisotropic wood-derived hydrogel composite membrane with fantastic antibacterial, anti-inflammatory, and osteogenic activities is expected to be ideal artificial periostea.

The mechanism of bone repair: Stem cells in the periosteum dedicated to bridging a large gap.

Bone repair requires the mobilization of stem cells from outer periosteum and inner bone marrow. A study by Jeffery et al.1 shows that periosteal stem cells are dedicated to repairing a large defect and regenerating both bone and marrow stroma.

Bone marrow-derived vasculogenesis leads to scarless regeneration in deep wounds with periosteal defects.

Deep skin wounds with periosteal defects, frequently caused by traffic accidents or radical dissection, are refractory. Transplant surgery is frequently performed, but patients are subjected to stress for long operation periods, the sacrifice of donor regions, or several complications, such as flap necrosis or intractable ulcers. Even if the defects are covered, a scar composed of fibrous tissue remains in the body, which can cause itching, dysesthesia, or repeated ulcers because of the lack of distribution of peripheral nerves or hair follicles. Thus, treatments with the aim of regenerating lost tissue for deep wounds with periosteal defects are needed. Here, we show that the use of gelatin sponges (GS), which have been used as haemostatic materials in clinical practice, allowed the regeneration of heterogeneous tissues, including periosteum, skin, and skin appendages, when used as scaffolds in deep wounds with periosteal defects in rats. Bone marrow transplantation in rats revealed the mechanism by which the microenvironment provided by GS enabled bone marrow-derived cells (BMDCs) to form a vascular niche, followed by regeneration of the periosteum, skin, or skin appendages such as hair follicles by local cells. Our findings demonstrated that vascular niche formation provided by BMDCs is crucial for heterogeneous tissue regeneration.

Tiron Has Negative Effects on Osteogenic Differentiation via Mitochondrial Dysfunction in Human Periosteum-Derived Cells.

Tiron is a potent antioxidant that counters the pathological effects of reactive oxygen species (ROS) production due to oxidative stress in various cell types. We examined the effects of tiron on mitochondrial function and osteoblastic differentiation in human periosteum-derived cells (hPDCs). Tiron increased mitochondrial activity and decreased senescence-associated ß-galactosidase activity in hPDCs; however, it had a detrimental effect on osteoblastic differentiation by reducing alkaline phosphatase (ALP) activity and alizarin red-positive mineralization, regardless of H2O2 treatment. Osteoblast-differentiating hPDCs displayed increased ROS production compared with non-differentiating hPDCs, and treatment with tiron reduced ROS production in the differentiating cells. Antioxidants decreased the rates of oxygen consumption and ATP production, which are increased in hPDCs during osteoblastic differentiation. In addition, treatment with tiron reduced the levels of most mitochondrial proteins, which are increased in hPDCs during culture in osteogenic induction medium. These results suggest that tiron exerts negative effects on the osteoblastic differentiation of hPDCs by causing mitochondrial dysfunction.

Periosteum Classification and Flap Advancement Techniques Around the Mental Foramen.

Various surgical flap advancement techniques for bone regeneration have been described in the literature; however, the clinical challenges of managing tissue that contains scars or embedded foreign materials have not been thoroughly described, especially around metal foramen. Fibrotic and thickened scar periosteum as well as mental foramen restrict the tissue from responding in the same way as native tissue. Therefore, additional considerations and approaches must be considered to achieve tension-free flap closure. This article presents a flap advancement classification that describes three common clinical scenarios based on the periosteum and soft tissue quality and provides surgical approaches for tissue management in each classification, with a focus on flap advancement around the mental foramen.

Bone marrow and periosteal skeletal stem/progenitor cells make distinct contributions to bone maintenance and repair.

A fundamental question in bone biology concerns the contributions of skeletal stem/progenitor cells (SSCs) in the bone marrow versus the periosteum to bone repair. We found that SSCs in adult bone marrow can be identified based on Lepr^cre and Adiponectin-cre/creER expression while SSCs in adult periosteum can be identified based on Gli1^creERT2 expression. Under steady-state conditions, new bone arose primarily from bone marrow SSCs. After bone injuries, both SSC populations began proliferating but made very different contributions to bone repair. Drill injuries were primarily repaired by LepR⁺/Adiponectin⁺ bone marrow SSCs. Conversely, bicortical fractures were primarily repaired by Gli1⁺ periosteal SSCs, though LepR⁺/Adiponectin⁺ bone marrow cells transiently formed trabecular bone at the fracture site. Gli1⁺ periosteal cells also regenerated LepR⁺ bone marrow stromal cells that expressed hematopoietic niche factors at fracture sites. Different bone injuries are thus repaired by different SSCs, with periosteal cells regenerating bone and marrow stroma after non-stabilized fractures.

Periosteum coverage versus collagen-membrane coverage in periodontally accelerated osteogenic orthodontics: a randomized controlled clinical trial in Class II and Class III malocclusions.

BACKGROUND: Periodontal accelerated osteogenic orthodontics (PAOO) is a widely-used clinical procedure that combines selective alveolar corticotomy, particulate bone grafting, and the application of orthodontic forces. Different modifications of PAOO such as collagen-membrane coverage can better benefit patients from preventing displacement of grafts. Due to its stability, collagen-membrane coverage gradually gained popularity and became a widely-used procedure in traditional PAOO technique. OBJECTIVES: To quantitatively investigate the radiographic changes of alveolar bone, periodontal soft tissue changes of the mandibular anterior teeth and postoperative complications in periosteum-covered techniques compared with traditional surgical technique in PAOO. METHODS: Orthodontic camouflage for dental Class II or decompensation for skeletal Class III malocclusions were included; Patients with bone defects on the buccal aspects of the anterior mandible regions confirmed by clinical and radiographic examination were randomly divided into the periosteum coverage group or traditional technique group for PAOO. Cone-beam computerized tomography (CBCT) scans were obtained before treatment (T0) and 1 week (T1) and 12 months (T2) after operation. The primary outcome variable was the vertical alveolar bone level (VBL), the secondary evaluation parameters included labial horizontal bone thickness at the midpoint of the middle third (MHBT) or apical third (AHBT) to the limit of the labial cortical surface during a 12-month follow-up. Postoperative sequelae were evaluated after 2 days and 7 days in both the groups. Periodontal parameters were analyzed at T0 and T2. RESULTS: Thirty-six adult subjects were eligible and recruited in the present study. Although experimental group exhibited more severe infection, no significant differences of the postoperative symptoms or periodontal parameters was found between the 2 groups (P > 0.05). All patients were examined respectively using CBCT at baseline (T0), postoperative 1 week (T1) and 12 months (T2). Both alveolar bone height and width increased from T0 to T1 (P < 0.001) and then reduced from T1 to T2 (P < 0.001) in both groups. However, significant bone augmentation was achieved in each group from T0 to T2 (P < 0.001). Furthermore, the vertical alveolar bone augmentation in the experimental group increased significantly than that in the traditional surgery (P < 0.05). CONCLUSIONS: Compared with traditional PAOO surgery, the periosteum-covered technique provides superior graft stabilization and satisfactory vertical bone augmentation in the labial mandibular anterior area.