Piezo1 and Piezo2 collectively regulate jawbone development.

Piezo1 and Piezo2 are recently reported mechanosensory ion channels that transduce mechanical stimuli from the environment into intracellular biochemical signals in various tissues and organ systems. Here, we show that Piezo1 and Piezo2 display a robust expression during jawbone development. Deletion of Piezo1 in neural crest cells causes jawbone malformations in a small but significant number of mice. We further demonstrate that disruption of Piezo1 and Piezo2 in neural crest cells causes more striking defects in jawbone development than any single knockout, suggesting essential but partially redundant roles of Piezo1 and Piezo2. In addition, we observe defects in other neural crest derivatives such as malformation of the vascular smooth muscle in double knockout mice. Moreover, TUNEL examinations reveal excessive cell death in osteogenic cells of the maxillary and mandibular arches of the double knockout mice, suggesting that Piezo1 and Piezo2 together regulate cell survival during jawbone development. We further demonstrate that Yoda1, a Piezo1 agonist, promotes mineralization in the mandibular arches. Altogether, these data firmly establish that Piezo channels play important roles in regulating jawbone formation and maintenance.

Integrated proteomics, phosphoproteomics and metabolomics analyses reveal similarities among giant cell granulomas of the jaws with different genetic mutations.

BACKGROUND: Giant cell granuloma of the jaws are benign osteolytic lesions of the jaws. These lesions are genetically characterized by mutually exclusive somatic mutations at TRPV4, KRAS, and FGFR1, and a fourth molecular subgroup which is wild-type for the three mutations. Irrespective of the molecular background, giant cell granulomas show MAPK/ERK activation. However, it remains unclear if these mutations lead to differences in their molecular signaling in giant cell granulomas. METHODS: Metabolomics, proteomics, and phosphoproteomics analyses were carried out in formalin-fixed paraffin-embedded samples of giant cell granuloma of the jaws. The study cohort consisted of five lesions harboring mutations in FGFR1, six in KRAS, five in TRPV4, and five that were wild-type for these mutations. RESULTS: Lesions harboring KRAS or FGFR1 mutations showed overall similar proteomics and metabolomics profiles. In all four groups, metabolic pathways showed similarity in apoptosis, cell signaling, gene expression, cell differentiation, and erythrocyte activity. Lesions harboring TRPV4 mutations showed a greater number of enriched pathways related to tissue architecture. On the other hand, the wild-type group presented increased number of enriched pathways related to protein metabolism compared to the other groups. CONCLUSION: Despite some minor differences, our results revealed an overall similar molecular profile among the groups with different mutational profile at the metabolic, proteic, and phosphopeptidic levels.

The Effects of NF-kB Inhibition with p65-TMD-Linked PTD on Inflammatory Responses at Peri-implantitis Sites.

The objective of this study was to find out if suppression of NF-kB complex function by p65-TMD-linked PTD could reduce host inflammation and bone resorption at peri-implantitis sites in rats. Twenty-one male 5-week-old SD rats were divided into three groups: untreated control group (A), silk-induced peri-implantitis group (B), and nt (nucleus transducible)-p65-TMD-treated, silk-induced peri-implantitis group (C). Implant sulcus of a rat in group C were divided into two groups, namely group Cp and Cb. Palatal implant sulcus where nt-p65-TMD solution was applied with an insulin syringe were assigned to group Cp. Buccal implant sulcus without topical nt-p65-TMD application were assigned to group Cb. H&E staining, TRAP staining, and immunohistological staining were done. The crestal bone levels of group A were significantly higher than those of group B at p<0.01. The crestal bone levels of group Cp were significantly higher than those of group Cb at p<0.05. H-E staining showed increased apical migration of junctional epithelium and inflammatory cells in group Cb. TRAP staining revealed more multinucleated osteoclasts in group Cb. As for immunohistological staining, group Cb showed many IL-6-positive cells while group Cp had none. In this study, p65-TMD-linked PTD inhibited NF-kB functions and reduced inflammation and bone resorption at peri-implantitis sites in rats.

Downregulation of miR­146a inhibits osteoporosis in the jaws of ovariectomized rats by regulating the Wnt/ß­catenin signaling pathway.

MicroRNAs (miRNAs or miRs) play important roles in osteoporosis and exhibit high potential in the therapeutic treatment of this condition. The present study aimed to explore the effects of miR­146a on bone loss noted in the jawbones of ovariectomized (OVX) rats and the interaction of miR­146a with the Wnt/ß­catenin signaling pathway. OVX Sprague­Dawley female rats were used to establish the animal model of osteoporosis (OP). Bone mineral density (BMD) was measured via dual­energy X­ray and the miR­146a levels were detected by reverse transcription­quantitative PCR. miR­146a antagonist (miR­146a­A) and negative control (miR­146a­NC) were used to examine the effects of miR­146a on OVX rats. The contents of osteocalcin and tartrate resistant phosphatase (TRAP) were detected via ELISA. Hematoxylin and eosin, and TRAP staining were used to observe the pathological changes and the number of osteoclasts in the jawbone, respectively. In addition, the expression levels of the nuclear factor of activated T cells c1 (NFATc1), c­Fos and cathepsin K (CTK) in the jawbone were detected by immunohistochemistry, whereas the expression levels of osteoprotegerin, TRAP, dickkopf1, Wnt2 and ß­catenin in the same tissues were assessed by western blot analysis. The Wnt2 activator (DKK2­C2) and inhibitor (endostatin) were used to examine the effects of miR­146a on the Wnt/ß­catenin pathway. The results indicated that the BMD was increased, whereas the contents of osteocalcin and TRAP were decreased in the miR­146a­A group compared with those noted in the OP or negative control groups (P<0.05). Although the trabecular bone area of the OP group was decreased, the conditions were improved in the miR­146a­A group. The number of osteoclasts was decreased in the miR­146a­A group compared with that noted in the OP group (P<0.05). The expression levels of NFATc1, c­Fos and CTK in the miR­146a­A group were decreased compared with those noted in the OP or negative control groups (P<0.05). Similar results were found following the comparison of the miR­146a­A group with the DKK2­C2 group. Taken together, these data demonstrated that miR­146a downregulation inhibited OP of the jawbone in OVX rats by activating the Wnt/ß­catenin signaling pathway.

Human Periodontal Ligament Stem Cells Transplanted with Nanohydroxyapatite/Chitosan/Gelatin 3D Porous Scaffolds Promote Jaw Bone Regeneration in Swine.

Dental-tissue-derived stem cells have been used for tissue engineering owing to their ease of isolation and efficacy in in vitro and in vivo proliferation and differentiation. Nanohydroxyapatite/chitosan/gelatin (nHA/CG) three-dimensional porous scaffolds are promising for bone tissue engineering, especially jaw bone regeneration, because of their structural and functional similarity to natural bone. In our previous study, the efficiency of scaffolds with stem cell complexes in osteogenesis was confirmed in vivo in immunocompromised mice. However, studies on the bone regeneration efficiency of stem cell-seeded nHA/CG scaffolds using large animal jaw bone defect models have not been conducted. This study evaluated the bone regeneration potential of the nHA/CG scaffolds with transplanted human periodontal ligament stem cells (hPDLSCs) in critical-sized jaw bone defects in minipigs. The hPDLSCs isolated from periodontal ligaments of discarded teeth (postorthodontic purposes) were seeded onto the nHA/CG scaffolds. The scaffold was successfully synthesized according to our previous studies. Forty-eight critical-sized jaw bone defects were created in 12 minipigs. The defects were randomly assigned to one of three groups [scaffolds with seeded hPDLSCs (hPDLSCs/nHA/CG), only scaffold (nHA/CG), and a negative control group, ie, no cells and scaffolds implanted into defects] to investigate jaw bone regeneration. The bone regeneration capacities of the three groups were assessed for up to 12 weeks. The results showed that the hPDLSCs adhered well to the nHA/CG scaffold in vitro, and the cell-nHA/CG composites significantly increased new bone formation and generated large bones with normal architectures and vascularization in vivo compared to the nHA/CG and control groups. Immunohistochemistry staining showed that runt-related transcription factor 2 (Runx2) was highly expressed in the bone marrow formed in the hPDLSCs/nHA/CG group. This study provides strong evidence for future clinical applications of the nHA/CG scaffolds transplanted with hPDLSCs to regenerate the bone in large jaw bone defects.

Effect of selected metals on bone tissue of the masticatory apparatus / Efectos de metales en el tejido óseo del aparato masticatorio

The masticatory apparatus is a functional unit of the human body, which is mainly responsible for speech, chewing, and swallowing. It is built of bones, joints, ligaments, teeth, and muscles. In addition, the oral cavity and its hard tissues are the first ones to be exposed to exogenous factors during feeding and breathing. The aim of the work was to review the literature of recent years on the toxicology of metals and their possible negative and sometimes positive effects on the metabolism of bones of the masticatory apparatus. In summary, metals commonly found in the environment affect the bones of the masticatory apparatus to varying degrees. Attention should be paid to the sources of individual metals in the environment and to prevent their excessive, unwanted effects on the bones of the masticatory apparatus. (AU)

El aparato masticatorio constituye una unidad funcional del cuerpo humano especializada en la regulación y coordinación de los procesos del habla, la masticación y la deglución. Está constituida por huesos, ligamentos, articulaciones, músculos y dientes. El tejido óseo de la cavidad bucal es el primero en estar expuesto a factores exógenos durante la alimentación y la respiración. El objetivo del presente trabajo es realizar una revisión de lo reportado en la literatura en los últimos años, con respecto a los efectos beneficiosos o nocivos de los metales pesados sobre el metabolismo de los huesos del aparato masticatorio. En resumen, se evidencia que los metales presentes en el medioambiente afectan a estos huesos en diferentes grados. Se debe prestar especial atención a identificar las fuentes de donde provienen estos metales, para prevenir los efectos no deseados sobre el tejido óseo masticatorio generados por una excesiva exposición a ellos. (AU)

Jaw Periosteal Cells Seeded in Beta-Tricalcium Phosphate Inhibit Dendritic Cell Maturation.

Mesenchymal stem cells (MSCs) have gained attraction not only in the field of regenerative medicine but also in the field of autoimmune disease therapies or organ transplantation due to their immunoregulatory and/or immunosuppressive features. Dendritic cells (DCs) play a crucial role in initiating and regulating immune reactions by promoting antigen-specific T cell activation. In this study, we investigated the effect of human jaw periosteal progenitor cells (JPCs) seeded in beta-tricalcium phosphate (ß-TCP) scaffolds on monocyte-derived DC differentiation. Significantly lower numbers of differentiated DCs were observed in the presence of normal (Co) and osteogenically induced (Ob) JPCs-seeded ß-TCP constructs. Gene expression analysis revealed significantly lower interleukin-12 subunit p35 (IL-12p35) and interleukin-12 receptor beta 2 (IL-12Rß2) and pro-inflammatory cytokine interferon-gamma (IFN-γ) levels in DCs under Ob conditions, while interleukin-8 (IL-8) gene levels were significantly increased. Furthermore, in the presence of JPCs-seeded ß-TCP constructs, interleukin-10 (IL-10) gene expression was significantly induced in DCs, particularly under Ob conditions. Analysis of DC protein levels shows that granulocyte-colony stimulating factor (G-CSF) was significantly upregulated in coculture groups. Our results indicate that undifferentiated and osteogenically induced JPCs-seeded ß-TCP constructs have an overall inhibitory effect on monocyte-derived DC maturation.

Demonstration of beta-tropomyosin (Tpm2) and duplication of the alpha-slow tropomyosin gene (TPM3) in Atlantic salmon Salmo salar.

Beta tropomyosin (Tpm2) is demonstrated for the first time at the protein level in a fish species, using a combination of electrophoresis, mass spectrometric peptide mapping and end-group analysis. Tpm2 accounts for 50% of the total tropomyosin in slow trunk muscle of the adult Atlantic salmon as determined by quantitative carboxypeptidase digestion and is also present in the head and pectoral fin. It is absent in the fast skeletal (lighter-toned) trunk muscle, the most abundant muscle, which is composed solely of an alpha-fast (Tpm1) isoform. In contrast to the mammalian homologues, salmon Tpm2 migrates faster than salmon Tpm1 in the presence of anionic detergent. Other distinguishing characteristics are a reduced content of cysteine (one per chain) and tyrosine (five per chain) and a unique carboxyl-terminal region (residues 276-284). Two isoforms (paralogs) of alpha-slow tropomyosin (Tpm3) having different contents of methionine and histidine exist in slow trunk muscle indicating duplication of the TPM3 gene. Minor skeletal muscles, surveyed for the first time, contain a mix of at least two tropomyosins - Tpm2 (~ 50% of total) in pectoral fin, jaw and tongue and another isoform, either Tpm1 (pectoral fin) or alpha-1-like Tpm (jaw and tongue). Cheek muscle contains Tpm1 and alpha 1-like Tpm in varying proportion depending upon the section (light or dark). Of the two tropomyosins in tongue, Tpm2 displays comparatively weaker affinity for troponin-Sepharose. A feature of the major sarcomeric tropomyosins in Atlantic salmon is a pair of neighbouring glycines situated between residues 20-90.

[Basic Studies on the Mechanism, Prevention, and Treatment of Osteonecrosis of the Jaw Induced by Bisphosphonates].

Since the first report in 2003, bisphosphonate-related osteonecrosis of the jaw (BRONJ) has been increasing, without effective clinical strategies. Osteoporosis is common in elderly women, and bisphosphonates (BPs) are typical and widely used anti-osteoporotic or anti-bone-resorptive drugs. BRONJ is now a serious concern in dentistry. As BPs are pyrophosphate analogues and bind strongly to bone hydroxyapatite, and the P-C-P structure of BPs is non-hydrolysable, they accumulate in bones upon repeated administration. During bone-resorption, BPs are taken into osteoclasts and exhibit cytotoxicity, producing a long-lasting anti-bone-resorptive effect. BPs are divided into nitrogen-containing BPs (N-BPs) and non-nitrogen-containing BPs (non-N-BPs). N-BPs have far stronger anti-bone-resorptive effects than non-N-BPs, and BRONJ is caused by N-BPs. Our murine experiments have revealed the following. N-BPs, but not non-N-BPs, exhibit direct and potent inflammatory/necrotic effects on soft-tissues. These effects are augmented by lipopolysaccharide (the inflammatory component of bacterial cell-walls) and the accumulation of N-BPs in jawbones is augmented by inflammation. N-BPs are taken into soft-tissue cells via phosphate-transporters, while the non-N-BPs etidronate and clodronate inhibit this transportation. Etidronate, but not clodronate, has the effect of expelling N-BPs that have accumulated in bones. Moreover, etidronate and clodronate each have an analgesic effect, while clodronate has an anti-inflammatory effect via inhibition of phosphate-transporters. These findings suggest that BRONJ may be induced by phosphate-transporter-mediated and infection-promoted mechanisms, and that etidronate and clodronate may be useful for preventing and treating BRONJ. Our clinical trials support etidronate being useful for treating BRONJ, although additional clinical trials of etidronate and clodronate are needed.

Impact of bisphosphonates on the proliferation and gene expression of human fibroblasts.

The aim of this study was to elucidate the role of fibroblasts in bisphosphonate-related osteonecrosis of the jaw (BRONJ), evaluating the effect of zoledronate, alendronate, and ibandronate on the proliferation of fibroblasts and on their expression of genes essential for fibroblast physiology. Human CCD-1064Sk epithelial fibroblast cells were incubated in culture medium with 10-5, 10-7, or 10-9 M zoledronate, alendronate, or ibandronate. The proliferative capacity of fibroblasts was determined by spectrophotometry (MTT) at 24 of culture. Real-time polymerase chain reaction (RT-PCR) was used to study the effects of BPs at a dose of 10-9 M on the expression of FGF, CTGF, TGF-ß1, TGFßR1, TGFßR2, TGFßR3, DDR2, α-actin, fibronectin, decorin, and elastin. Fibroblasts proliferation was significantly increased at the lowest dose (10-9M) of each BP but was not affected at the higher doses (10-5 and 10-7M). The proliferation increase may be related to the rise in TGF-ß1 and TGFßR1 expression detected after the treatment of cells with 10-9M of zoledronate, alendronate, or ibandronate. However, the expression of CTGF, DDR2, α-actin, fibronectin, and decorin decreased versus controls. The results of this in vitro study indicate that a very low BP dose (10-9 M) can significantly affect the physiology of fibroblasts, increasing their proliferative capacity and modulating the expression of multiple genes involved in their growth and differentiation.

Metastatic tumors in oral mucosa and jawbones: Unusual primary origins and unusual oral locations.

AIM: To perform clinico-pathological characterization of a large series of oral metastases, collected from 3 main medical centers in Israel and compare findings to data on frequency of primary cancer types in the population. MATERIALS: Pathology archives were searched for cases of metastatic tumors to the oral soft tissues and jawbones, 1990 - 2016. Metastases to the skin of face or to major salivary glands have been excluded. Demographic data and histopathological features were analyzed. RESULTS: Study population included 60 patients, 35 females and 25 males (ratio of 1.4:1). The age range was 17-87 years, mean 67.7 + 14.36 years. Only 3 (5%) patients were under 40 years, the remaining clustered predominantly in the 60-80 year age group. The mean age of females (59 + 13.84) was significantly lower than that of males (67.44 + 14) (p = 0.03). There was an almost equal distribution between the oral soft tissue and the jawbones (48.3% and 51.7%, respectively). The five most common organs from which metastases were distributed to the oral cavity and jawbones combined were kidney (20%), breast (15%), cutaneous (predominately melanoma, 13%), lung (11.7%) and soft tissue-sarcomas (8.3%). For comparison, Israel National Cancer Registry 2013 reported that the most frequent malignancies were breast (25.8%), colorectal cancer (16.3%), lung (12%) and prostate (10%). Malignant melanoma was 6th (5.4%), kidney malignancy was only 9th in frequency (4.2%). Although the gingiva and jawbones were the most frequent locations, some cases presented in unusual locations, (mandibular vestibule, lower lip, posterior dorsal tongue), without any specific clinical feature to suggest metastasis. CONCLUSIONS: The most frequent primary origins for oral metastasis do not correspond to the relative frequency of the primary tumors in the population, indicating that metastatic spread is not a random process. Although the majority of metastasis involves the gingiva and jawbones, any other oral mucosal location might be involved. Thus, in adult/older patients, metastasis from a distant site should be included in the differential diagnosis of oral masses at any oral location, whether the existence of a primary tumor is reported or not.

Tissue regeneration during lower jaw restoration in zebrafish shows some features of epimorphic regeneration.

Zebrafish have the ability to regenerate skeletal structures, including the fin, skull roof, and jaw. Although fin regeneration proceeds by epimorphic regeneration, it remains unclear whether this process is involved in other skeletal regeneration in zebrafish. Initially in epimorphic regeneration, the wound epidermis covers the wound surface. Subsequently, the blastema, an undifferentiated mesenchymal mass, forms beneath the epidermis. In the present study, we re-examined the regeneration of the zebrafish lower jaw in detail, and investigated whether epimorphic regeneration is involved in this process. We performed amputation of the lower jaw at two different positions; the proximal level (presence of Meckel's cartilage) and the distal level (absence of Meckel's cartilage). In both manipulations, a blastema-like cellular mass was initially formed. Subsequently, cartilaginous aggregates were formed in this mass. In the proximal amputation, the cartilaginous aggregates were then fused with Meckel's cartilage and remained as a skeletal component of the regenerated jaw, whereas in the distal amputation, the cartilaginous aggregates disappeared as regeneration progressed. Two molecules that were observed during epimorphic regeneration, Laminin and msxb, were expressed in the regenerating lower jaw, although the domain of msxb expression was out of the main plain of the aggregate formation. Administration of an inhibitor of Wnt/ß-catenin signaling, a pathway associated with epimorphic regeneration, showed few effects on lower jaw regeneration. Our finding suggests that skeletal regeneration of the lower jaw mainly progresses through tissue regeneration that is dependent on the position in the jaw, and epimorphic regeneration plays an adjunctive role in this regeneration.

FGF signaling patterns cell fate at the interface between tendon and bone.

Tendon and bone are attached by a transitional connective tissue that is morphologically graded from tendinous to osseous and develops from bipotent progenitors that co-express scleraxis (Scx) and Sox9 (Scx+/Sox9+). Scx+/Sox9+ progenitors have the potential to differentiate into either tenocytes or chondrocytes, yet the developmental mechanism that spatially resolves their bipotency at the tendon-bone interface during embryogenesis remains unknown. Here, we demonstrate that development of Scx+/Sox9+ progenitors within the mammalian lower jaw requires FGF signaling. We find that loss of Fgfr2 in the mouse tendon-bone interface reduces Scx expression in Scx+/Sox9+ progenitors and induces their biased differentiation into Sox9+ chondrocytes. This expansion of Sox9+ chondrocytes, which is concomitant with decreased Notch2-Dll1 signaling, prevents formation of a mixed population of chondrocytes and tenocytes, and instead results in ectopic endochondral bone at tendon-bone attachment units. Our work shows that FGF signaling directs zonal patterning at the boundary between tendon and bone by regulating cell fate decisions through a mechanism that employs Notch signaling.

Pentosidine correlates with nanomechanical properties of human jaw bone.

Initial intimate apposition between implant fixtures and host bone at the surgical site is a critical factor for osseointegration of dental implants. The advanced glycation end products accumulated in the jaw bone could lead to potential failure of a dental implant during the initial integration stage, because of the inferior bone mechanical property associated with the abnormal collagen cross-linking at the material level. Here, we demonstrate the lowered creep deformation resistance and reduced dimensional recovery of jaw bone in line with high levels of pentosidine accumulation in the bone matrix which likely correlate with the pentosidine level in blood plasma. Peripheral blood samples and cortical bone samples at the surgical site were obtained from patients scheduled for dental implants in the mandible. The pentosidine levels in blood plasma were assessed. Subsequently, the relative pentosidine levels and the mechanical properties of the jaw bone were quantified by Raman microspectroscopy and nanoindentation, respectively. The nanoindentation tests revealed less creep deformation resistance and reduced time-dependent dimensional recovery of bone samples with the increase in the relative pentosidine level in the bone matrix. Higher tan δ values at the various frequencies during the dynamic indentation tests also suggested that viscoelasticity is associated with the relative intensity of pentosidine in the jaw bone matrix. We found a positive correlation between the pentosidine levels in blood plasma and the bone matrix, which in turn reduced the mechanical property of the jaw bone at the material level. Increased creep and reduced dimensional recovery of the jaw bone may diminish the mechanical interlocking of dental implants during the initial integration stage. Given the likely correlation between the plasma pentosidine level and the mechanical properties of bone, measurement of the plasma pentosidine level could serve as a new index to assess jaw bone matrix quality in advance of implant surgery.

Vasculature submucosal changes at early stages of osteonecrosis of the jaw (ONJ).

Osteonecrosis of the jaw (ONJ), a rare, but potentially severe side effect of anti-resorptive medications, presents as exposed bone in the maxillofacial region lasting for at least 8 weeks. While clinical experience and animal models concur in finding that systemic antiresorptive treatment in conjunction with local risk factors, such as tooth extraction or dental disease may lead to ONJ development, the subclinical molecular changes that precede bone exposure remain poorly understood. The identification of these changes is not only important in understanding disease pathophysiology, but could provide potential for treatment development. Here, we evaluated the early stages of ONJ utilizing a model of experimental periodontitis (EP) in mice treated with two different types of antiresorptives, targeting potential changes in vasculature, hypoxia, oxidative stress, and apoptosis. Antiresorptive treatment in animals with EP increased levels of empty osteocytic lacunae and increased ONJ prevalence compared to Veh animals. The arteriole and venule network seen around EP areas was diminished in animals treated with antiresorptives. Higher levels of vascular endothelial growth factor A (VEGF-A) and vascular cell adhesion protein-1 (VCAM-1) were observed 1-week following EP in treated animals. Finally, levels of hypoxia, oxidative stress, and apoptosis remained high in antiresorptive treated animals with EP through the duration of the experiment. Together, our data point to subclinical vasculature organizational disturbances that subsequently affect levels of hypoxia, oxidative stress, and apoptosis in the area of developing ONJ.

Development and validation of a method using ultra performance liquid chromatography coupled to tandem mass spectrometry for determination of zoledronic acid concentration in human bone.

A method for the extraction and quantification of zoledronic acid (ZA) from human bone was set up and validated. This method allowed the quantification of ZA from jawbone sequestrations of patients affected by bisphosphonate-related osteonecrosis of the jaw (BRONJ) associated with ZA treatment. The analyte was extracted from the bone tissues with phosphoric acid and derivatized using trimethylsilyl diazomethane (TMS-DAM). ZA tetramethyl phosphonate was then quantified by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS), showing high accuracy, repeatability and selectivity. Lower limits of quantification and detection (LLOQ and LLQD) were 3.4 ng/mL and 1 ng/mg, respectively. This study fully described the analytical process for the determination of ZA in human bone sequestrations, representing a pivotal step for further biomedical research on ZA and BRONJ.

Implant-associated gene expression in the jaw bone of smokers and nonsmokers: A human study using quantitative qPCR.

OBJECTIVES: This study aimed to compare the molecular events in implant-adherent cells and in peri-implant bone during the osseointegration of machined and oxidized titanium implants in smokers and nonsmokers. MATERIALS AND METHODS: Twenty-four smokers and 24 nonsmokers each received machined and anodically oxidized mini-implants. The mini-implants and the surrounding bone were retrieved after 1, 7, and 28 days, for gene expression analysis of selected factors using quantitative polymerase chain reaction (qPCR). RESULTS: Differences between machined and oxidized implants were more evident in the implant-adherent cells than the peri-implant bone. The machined implants revealed higher expression of proinflammatory cytokines, interleukin-8 (IL-8) (in nonsmokers), and tumor necrosis factor-alpha (in nonsmokers and smokers), compared with the oxidized implants. Conversely, the expression of bone formation genes, alkaline phosphatase and osteocalcin, was generally higher at the oxidized implants. In smokers, the temporal pattern revealed the delayed and initial inhibition of osteoblastic and osteoclastic gene expression, respectively, mainly at the machined implants. In contrast, oxidized implants revealed higher expression of bone remodeling, cathepsin K (CatK) and calcitonin receptor, and coupling, receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin, genes after 7 day in smokers. CONCLUSIONS: The implant-adherent cells are more sensitive to surface properties and smoking conditions than the cells in the peri-implant bone. Smoking imposes inhibitory effects on the initial molecular events of osseointegration in the human bone-implant interface. The surface properties of oxidized implants appear to have a beneficial effect on osseointegration by mitigating the smoking-induced negative effects.

Bapx1 is required for jaw joint development in amphibians.

The acquisition of a movable jaw and a jaw joint are key events in gnathostome evolution. Jaws are derived from the neural crest derived pharyngeal skeleton and the transition from jawless to jawed vertebrates consists of major morphological changes, which must have a genetic foundation. Recent studies on the effects of bapx1 knockdown in fish and chicken indicate that bapx1 has acquired such a role in primary jaw joint development during vertebrate evolution, but evidence from amphibians is missing so far. In the present study, we use Ambystoma mexicanum, Bombina orientalis, and Xenopus laevis to investigate the effects of bapx1 knockdown on the development of these three different amphibians. Using morpholinos we downregulated the expression of bapx1 and obtain morphants with altered mandibular arch morphology. In the absence of bapx1 Meckels cartilage and the palatoquadrate jaw joint initially develop separately but during further development the joint cavity between both fills with chondrocytes. This results in the fusion of both cartilages and the loss of the jaw joint. Despite this the jaw itself remains usable for feeding and breathing. We show that bapx1 plays a role in jaw joint maintenance during development and that the morphants morphology possibly mirrors the morphology of the jawless ancestors of the gnathostomes.

Bony pseudoteeth of extinct pelagic birds (Aves, Odontopterygiformes) formed through a response of bone cells to tooth-specific epithelial signals under unique conditions.

Modern birds (crown group birds, called Neornithes) are toothless; however, the extinct neornithine Odontopterygiformes possessed bone excrescences (pseudoteeth) which resembled teeth, distributed sequentially by size along jaws. The origin of pseudoteeth is enigmatic, but based on recent evidence, including microanatomical and histological analyses, we propose that conserved odontogenetic pathways most probably regulated the development of pseudodentition. The delayed pseudoteeth growth and epithelium keratinization allowed for the existence of a temporal window during which competent osteoblasts could respond to oral epithelial signaling, in place of the no longer present odontoblasts; thus, bony pseudoteeth developed instead of true teeth. Dynamic morphogenetic fields can explain the particular, sequential size distribution of pseudoteeth along the jaws of these birds. Hence, this appears as a new kind of deep homology, by which ancient odontogenetic developmental processes would have controlled the evolution of pseudodentition, structurally different from a true dentition, but morphologically and functionally similar.

Maxillary Bone Regeneration Based on Nanoreservoirs Functionalized ε-Polycaprolactone Biomembranes in a Mouse Model of Jaw Bone Lesion.

Current approaches of regenerative therapies constitute strategies for bone tissue reparation and engineering, especially in the context of genetical diseases with skeletal defects. Bone regeneration using electrospun nanofibers' implant has the following objectives: bone neoformation induction with rapid healing, reduced postoperative complications, and improvement of bone tissue quality. In vivo implantation of polycaprolactone (PCL) biomembrane functionalized with BMP-2/Ibuprofen in mouse maxillary defects was followed by bone neoformation kinetics evaluation using microcomputed tomography. Wild-Type (WT) and Tabby (Ta) mice were used to compare effects on a normal phenotype and on a mutant model of ectodermal dysplasia (ED). After 21 days, no effect on bone neoformation was observed in Ta treated lesion (4% neoformation compared to 13% in the control lesion). Between the 21st and the 30th days, the use of biomembrane functionalized with BMP-2/Ibuprofen in maxillary bone lesions allowed a significant increase in bone neoformation peaks (resp., +8% in mutant Ta and +13% in WT). Histological analyses revealed a neoformed bone with regular trabecular structure, areas of mineralized bone inside the membrane, and an improved neovascularization in the treated lesion with bifunctionalized membrane. In conclusion, PCL functionalized biomembrane promoted bone neoformation, this effect being modulated by the Ta bone phenotype responsible for an alteration of bone response.