Influence of effective number of pulses on the morphological structure of teeth and bovine femur after femtosecond laser ablation

Femtosecond lasers have been widely used in laser surgery as an instrument for contact-free tissue removal of hard dental, restorative materials, and osseous tissues, complementing conventional drilling or cutting tools. In order to obtain a laser system that provides an ablation efficiency comparable to mechanical instruments, the laser pulse rate must be maximal without causing thermal damage. The aim of this study was to compare the different morphological characteristics of the hard tissue after exposure to lasers operating in the femtosecond pulse regime. Two different kinds of samples were irradiated: dentin from human extracted teeth and bovine femur samples. Different procedures were applied, while paying special care to preserving the structures. The incubation factor S was calculated to be 0.788 +/- 0.004 for the bovine femur bone. These results indicate that the incubation effect is still substantial during the femtosecond laser ablation of hard tissues. The plasma-induced ablation has reduced side effects, i.e., we observe less thermal and mechanical damage when using a superficial femtosecond laser irradiation close to the threshold conditions. In the femtosecond regime, the morphology characteristics of the cavity were strongly influenced by the change of the effective number of pulses. (C) 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.JBO.17.4.048001]

Buccal Bone Plate Remodeling After Immediate Implant Placement With and Without Synthetic Bone Grafting and Flapless Surgery: Radiographic Study in Dogs

Recent studies in animals have shown pronounced resorption of the buccal bone plate after immediate implantation. The use of flapless surgical procedures prior to the installation of immediate implants, as well as the use of synthetic bone graft in the gaps represent viable alternatives to minimize buccal bone resorption and to favor osseointegration. The aim of this study was to evaluate the healing of the buccal bone plate following immediate implantation using the flapless approach, and to compare this process with sites in which a synthetic bone graft was or was not inserted into the gap between the implant and the buccal bone plate. Lower bicuspids from 8 dogs were bilaterally extracted without the use of flaps, and 4 implants were installed in the alveoli in each side of the mandible and were positioned 2.0 mm from the buccal bone plate (gap). Four groups were devised: 2.0-mm subcrestal implants (3.3 x 8 mm) using bone grafts (SCTG), 2.0-mm subcrestal implants without bone grafts (SCCG), equicrestal implants (3.3 x 10 mm) with bone grafts (EGG), and equicrestal implants without bone grafts (ECCG). One week following the surgical procedures, metallic prostheses were installed, and within 12 weeks the dogs were sacrificed. The blocks containing the individual implants were turned sideways, and radiographic imaging was obtained to analyze the remodeling of the buccal bone plate. In the analysis of the resulting distance between the implant shoulder and the bone crest, statistically significant differences were found in the SCTG when compared to the ECTG (P = .02) and ECCG (P = .03). For mean value comparison of the resulting linear distance between the implant surface and the buccal plate, no statistically significant difference was found among all groups (P > .05). The same result was observed in the parameter for presence or absence of tissue formation between the implant surface and buccal plate. Equicrestally placed implants, in this methodology, presented little or no loss of the buccal bone. The subcrestally positioned implants presented loss of buccal bone, even though synthetic bone graft was used. The buccal bone, however, was always coronal to the implant shoulder.

Morphological characterization of the progenitor blood cells in canine and feline umbilical cord

The umbilical cord blood (UCB) is an important source of hematopoietic stem cells with great deal of interest in regenerative medicine. The UCB cells have been extensively studied as an alternative to the bone marrow transplants. The challenge is to define specific methods to purify and characterize these cells in different animal species. This study is aimed at morphological characterization of progenitor cells derived from UCB highlighting relevant differences with peripheral blood of adult in dog and cats. Therefore, blood was collected from 18 dogs and 5 cats' umbilical cords from fetus in various developmental stages. The mononuclear cells were separated using the gradient of density Histopaque-1077. Characterization of CD34+ cells was performed by flow cytometric analysis and transmission electron microscopy. Granulocytes (ancestry of the basophiles, eosinophiles, and neutrophiles) and agranulocytes (represented by immature lymphocytes) were identified. We showed for the first time the ultrastructural features of cat UCB cells. Microsc. Res. Tech. 75:766770, 2012. (C) 2011 Wiley Periodicals, Inc.

Does Adjunctive Chemotherapy Reduce Remission Rates Compared to Cortisone Alone in Unifocal or Multifocal Histiocytosis of Bone?

Langerhans cell histiocytosis (LCH) is a rare disorder that can affect almost any organ, including bone. Treatment options include local corticosteroid infiltration in isolated bone lesions and oral corticosteroids and chemotherapy in multifocal bone lesions. Several studies show local corticosteroid injection in unifocal bone lesions heal in more than 75% of patients with minimal side effects. Therefore, it is unclear whether chemotherapy adds materially to the healing rate. We therefore compared overall survival, remission rate, and recurrence rate in patients with bone LCH treated with chemotherapy and corticosteroids or corticosteroids alone. We retrospectively reviewed the records of 198 patients with LCH since 1950. Median age at diagnosis was 5 years, male-to-female ratio was 1.33, and the most frequent symptom was local pain (95%). We recorded the disease presentation, demographics, treatment, and clinical evolution of each patient. Minimum followup was 4 months (median, 24 months; range, 4-360 months). The survival rate of the systemic disease group was 76.5% (65 of 85) while the survival rate in the unifocal and multifocal bone involvement groups was 100% at a median 5-year followup. All patients with unifocal bone involvement and 40 of 43 (93%) with multifocal bone involvement had complete remission. One of 30 patients with multifocal bone involvement treated with chemotherapy and oral corticosteroids did not achieve remission whereas two of six receiving only corticosteroids did not achieve remission. Our observations suggest intralesional corticosteroid injection without adjunctive chemotherapy achieves remission in unifocal bone LCH but may not do so in multifocal single-system bone involvement. Larger series would be required to confirm this observation. Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

On wing disparity and morphological variation of the Santana Group pterosaurs

Pterosaurs were widely spread throughout the Mesozoic Era, populating the whole world. Among this great diversity, two groups are commonly found in Brazil: the Anhangueridae and Tapejaridae. These can be mainly identified by cranial synapomorphies. However, because of the fragility of the pterosaur skeleton and rarity of the fossilisation process, the fossils found are usually incomplete, which hampers a proper taxonomic identification of the specimens. The specific proportions of these two groups of pterosaurs were obtained from bibliographic data and measurements of specimens. Eight Anhangueridae-like and seven Tapejaridae were used: Anhanguera piscator, Anhanguera santanae, Anhanguera spielbergi, Araripesaurus castilhoi, Barbosania gracilisrostris and three Anhangueridae sp. indet.; Sinopterus dongi, Tapejara wellnhoferi and five Tapejaridae sp. indet. We find that proportions of the humerus, wing metacarpal, first phalanx of the wing digit, femur and tibia are sufficient to identify partial remains of Araripe pterosaurs. A principal component analysis shows that each clade has different, non-overlapping scores in the studied ratios and these can be used with precision. Specific bone ratios for fast identification of anhanguerids and tapejarids are given, opening a broader way to diagnostic fragmentary bones.

Temporal modifications in bone following spinal cord injury in rats

Introduction: The aim of this study was to investigate the temporal modifications in bone mass, bone biomechanical properties and bone morphology in spinal cord injured rats 2, 4 and 6 weeks after a transection. Material and methods: Control animals were randomly distributed into four groups (n = 10 each group): control group (CG) - control animals sacrificed immediately after surgery; spinal cord-injured 2 weeks (2W) - spinal cord-injured animals sacrificed 2 weeks after surgery; spinal cord-injured 4 weeks (4W) - spinal cord-injured animals sacrificed 4 weeks after surgery; spinal cord-injured 6 weeks (6W) - spinal cord-injured animals sacrificed 6 weeks after surgery. Results: Biomechanical properties of the right tibia were determined by a threepoint bending test and injured animals showed a statistically significant decrease in maximal load compared to control animals. The right femur was used for densitometric analysis and bone mineral content of the animals sacrificed 4 and 6 weeks after surgery was significantly higher compared to the control animals and animals sacrificed 2 weeks after surgery. Histopathological and morphological analysis of tibiae revealed intense resorptive areas in the group 2 weeks after injury only. Conclusions: The results of this study show that this rat model is a valuable tool to investigate bone remodeling processes specifically associated with SCI. Taken together, our results suggest that spinal cord injury induced bone loss within 2 weeks after injury in rats.

Topical Insulin Accelerates Wound Healing in Diabetes by Enhancing the AKT and ERK Pathways: A Double-Blind Placebo-Controlled Clinical Trial

Background: Wound healing is impaired in diabetes mellitus, but the mechanisms involved in this process are virtually unknown. Proteins belonging to the insulin signaling pathway respond to insulin in the skin of rats. Objective: The purpose of this study was to investigate the regulation of the insulin signaling pathway in wound healing and skin repair of normal and diabetic rats, and, in parallel, the effect of a topical insulin cream on wound healing and on the activation of this pathway. Research Design and Methods: We investigated insulin signaling by immunoblotting during wound healing of control and diabetic animals with or without topical insulin. Diabetic patients with ulcers were randomized to receive topical insulin or placebo in a prospective, double-blind and placebo-controlled, randomized clinical trial (NCT 01295177) of wound healing. Results and Conclusions: Expression of IR, IRS-1, IRS-2, SHC, ERK, and AKT are increased in the tissue of healing wounds compared to intact skin, suggesting that the insulin signaling pathway may have an important role in this process. These pathways were attenuated in the wounded skin of diabetic rats, in parallel with an increase in the time of complete wound healing. Upon topical application of insulin cream, the wound healing time of diabetic animals was normalized, followed by a reversal of defective insulin signal transduction. In addition, the treatment also increased expression of other proteins, such as eNOS (also in bone marrow), VEGF, and SDF-1 alpha in wounded skin. In diabetic patients, topical insulin cream markedly improved wound healing, representing an attractive and cost-free method for treating this devastating complication of diabetes.

Systemically alendronate was incorporated into dental tissues but did not cause morphological or mechanical changes in rats teeth

This study evaluated the effect of the systemic use of sodium alendronate in rats in vivo. Forty-five Wistar rats aged 36 to 42 days and weighing 200 to 230 g were randomly assigned to a control group (n = 20), which received distilled water, and an experimental group (n = 25), which received 2 weekly doses of 1 mg/kg of chemically pure sodium alendronate. The animals were killed after 60 days of treatment. The tibias were removed for analysis of bone mineral density by dual-energy X-ray absorptiometry (DXA). Then, the maxillary incisors were extracted for analysis of the mineralized dental tissues using fluorescence spectroscopy (FS), scanning electron microscopy (SEM), bright field microscopy (BFM), and cross-sectional microhardness (CSMH) testing. DXA and CSMH data were subjected to statistical analysis by Kruskal-Wallis test (5% significance level). The experimental group presented higher bone mineral density than the control group by DXA. FS analysis revealed presence of alendronate in the mineralized dental tissues of the specimens of the experimental group. Significant morphological differences were not found by SEM and BFM. Enamel and dentin (100 and 300 mu m from the dentinoenamel junction) CSMH data did not show significant difference between the control and experimental groups. Based on the obtained results, we conclude that while alendronate increased the bone mineral density and was incorporated into the mineralized dental tissues it did not cause significant alterations in the morphology and microhardness of rat incisor enamel and dentin. Microsc. Res. Tech. 75:12651271, 2012. (C) 2012 Wiley Periodicals, Inc.

Association of laser phototherapy with PRP improves healing of bisphosphonate-related osteonecrosis of the jaws in cancer patients: A preliminary study

The aim of this study was to compare retrospectively the effect of three different treatments on the healing outcome of bisphosphonate-related osteonecrosis of the jaws (BRONJ) in cancer patients. Twenty-two cancer patients were treated for BRONJ with one of the following protocols: clinical (pharmacological therapy), surgical (pharmacological plus surgical therapy), or PRP plus LPT (pharmacological plus surgical plus platelet rich plasma (PRP) plus laser phototherapy (LPT). The laser treatment was applied with a continuous diode laser (InGaAlP, 660 nm) using punctual and contact mode, 40 mW, spot size 0.042 cm(2), 6 J/cm(2) (6 s) and total energy of 0.24 J per point. The irradiations were performed on the exposed bone and surrounding soft tissue. The analysis of demographic data and risk factors was performed by gathering the following information: age, gender, primary tumor, bisphosphonate (BP) used, duration of BP intake, history of chemotherapy, use of steroids, and medical history of diabetes. The association between the current state of BRONJ (with or without bone exposure) and other qualitative variables was determined using the chi-square or Fisher's exact test. In all tests, the significance level adopted was 5%. Most BRONJ lesions occurred in the mandible (77%) after tooth extraction (55%) and in women (72%). A significantly higher percentage of patients reached the current state of BRONJ without bone exposure (86%) in the PPR plus LPT group than in the pharmacological (0%) and surgical (40%) groups after 1-month follow-up assessment. These results suggest that the association of pharmacological therapy and surgical therapy with PRP plus LPT significantly improves BRONJ healing in oncologic patients. Although prospective studies with larger sample sizes are still needed, this preliminary study may be used to inform a better-designed future study. (C) 2011 Elsevier Ltd. All rights reserved.

The impact of healing time before loading on orthodontic mini-implant stability: a histomophometric study in minipigs

Objective: To evaluate healing time before loading, areas compression and tension and location of insertion on mini-implant stability. Design: Six minipigs were used. Each animal received 3 mini-implants in each quadrant: 1 mini-implant was used as an unloaded control (G1, n = 24); the other 2 were loaded with 150 g-force at three time intervals (G2: immediate loading, G3: after 15 days and G4: after 30 days), with 16 mini-implant in each experimental group. After 120 days, tissue blocks of the areas of interest were harvested. Clinical analysis (exact Fisher test) determined the survival rate. Histological analysis (Kontron KS 300TM, Zeiss) quantified the fractional bone-toimplant contact (%BIC) and bone area (%BA) at each healing time point, areas of interest, and insertion site (ANOVA and t tests for dependent and independent samples). Results: The mini-implant survival rates were G1: 71%, G2: 50%, G3: 75% and G4: 63%, with no statistical differences between them. The groups presented similar %BIC and %BA. There were no differences between the compression and tension sides or maxillary and mandibular insertion sites. Conclusions: These results suggest that low-intensity immediate or early orthodontic loading does not affect mini-implant stability, because similar histomorphometric results were observed for all the groups, with partial osseointegration of the mini-implants present.

Synthesis and characterization of implants for bone substitutions made of biomedical apatites containing silicon

In the last decades the development of bone substitutes characterized by a superior biomimetism has become of particular interest, owing to the increasing economic and societal impact of the bone diseases. In the present work of research the development of bone substitutes characterized by improved biomimetism, has been faced in a chemical, structural and morphological perspective. From a chemical point of view, it has been developed the synthesis of hydroxyapatite powders, exhibiting multiple ionic substitutions in both cationic and anionic sites, so to simulate the chemical composition of the natural bone. Particular emphasis has been given to the effect of silicon on the chemical-physical and solubility properties of the obtained hydroxyapatites. From a structural point of view, it has been developed the synthesis of ceramic composite materials, based on hydroxyapatite and calcium silicates, employed both as a reinforcing phase, to raise the mechanical strength of the composite compared to hydroxyapatite, and as a bioactive phase, able to increase the bioactivity properties of the whole ceramic. Finally the unique morphological features of the bone were mimicked by taking inspiration by Nature, so that native wood structures were treated in chemical and thermal way to obtain hydroxyapatite porous materials characterized by the same morphology as the native wood. The results obtained in the present work were positive in all the three different areas of investigation, so to cover the three different aspects of biomimetism, chemical, structural and morphological. Anyway, only at the convergence of the three different fields it is possible to find out the best solutions to develop the ideal bone-like scaffold. Thus, the future activity should be devoted to solve the problems at the borderline between the different research lines, which hamper this convergence and in consequence, the achievement of a bone scaffold able to mimic the various aspects exhibited by the bone tissue

Development of newly conceived biomimetic nano-structured biomaterials as scaffolds for bone and osteochondral regeneration

The present research thesis was focused on the development of new biomaterials and devices for application in regenerative medicine, particularly in the repair/regeneration of bone and osteochondral regions affected by degenerative diseases such as Osteoarthritis and Osteoporosis or serious traumas. More specifically, the work was focused on the synthesis and physico-chemical-morphological characterization of: i) a new superparamagnetic apatite phase; ii) new biomimetic superparamagnetic bone and osteochondral scaffolds; iii) new bioactive bone cements for regenerative vertebroplasty. The new bio-devices were designed to exhibit high biomimicry with hard human tissues and with functionality promoting faster tissue repair and improved texturing. In particular, recent trends in tissue regeneration indicate magnetism as a new tool to stimulate cells towards tissue formation and organization; in this perspective a new superparamagnetic apatite was synthesized by doping apatite lattice with di-and trivalent iron ions during synthesis. This finding was the pin to synthesize newly conceived superparamagnetic bone and osteochondral scaffolds by reproducing in laboratory the biological processes yielding the formation of new bone, i.e. the self-assembly/organization of collagen fibrils and heterogeneous nucleation of nanosized, ionically substituted apatite mimicking the mineral part of bone. The new scaffolds can be magnetically switched on/off and function as workstations guiding fast tissue regeneration by minimally invasive and more efficient approaches. Moreover, in the view of specific treatments for patients affected by osteoporosis or traumas involving vertebrae weakening or fracture, the present work was also dedicated to the development of new self-setting injectable pastes based on strontium-substituted calcium phosphates, able to harden in vivo and transform into strontium-substituted hydroxyapatite. The addition of strontium may provide an anti-osteoporotic effect, aiding to restore the physiologic bone turnover. The ceramic-based paste was also added with bio-polymers, able to be progressively resorbed thus creating additional porosity in the cement body that favour cell colonization and osseointegration.

Bioinspired fabrication of biosilica-based bone substitution materials

Until today, autogenic bone grafts from various donor regions represent the gold standard in the field of bone reconstruction, providing both osteoinductive and osteoconductive characteristics. However, due to low availability and a disequilibrium between supply and demand, the risk of disease transfer and morbidity, usually associated with autogeneic bone grafts, the development of biomimic materials with structural and chemical properties similar to those of natural bone have been extensively studied. So far,rnonly a few synthetic materials, so far, have met these criteria, displaying properties that allow an optimal bone reconstitution. Biosilica is formed enzymatically under physiological-relevant conditions (temperature and pH) via silicatein (silica protein), an enzyme that was isolated from siliceous sponges, cloned, and prepared in a recombinant way, retaining its catalytic activity. It is biocompatible, has some unique mechanical characteristics, and comprises significant osteoinductive activity.rnTo explore the application of biosilica in the fields of regenerative medicine,rnsilicatein was encapsulated, together with its substrate sodium metasilicate, into poly(D,L-lactide)/polyvinylpyrrolidone(PVP)-based microspheres, using w/o/wrnmethodology with solvent casting and termed Poly(D,L-lactide)-silicatein silicacontaining-microspheres [PLASSM]. Both silicatein encapsulation efficiency (40%) and catalytic activity retention upon polymer encapsulation were enhanced by addition of an essential pre-emulsifying step using PVP. Furthermore, the metabolic stability, cytoxicity as well as the kinetics of silicatein release from the PLASSM were studied under biomimetic conditions, using simulated body fluid. As a solid support for PLASSM, a polyvinylpyrrolidone/starch/Na2HPO4-based matrix (termed plastic-like filler matrix containing silicic acid [PMSA]) was developed and its chemical and physical properties determined. Moreover, due to the non-toxicity and bioinactivity of the PMSA, it is suggested that PMSA acts as osteoconductive material. Both components, PLASSM and PMSA, when added together, form arnbifunctional 2-component implant material, that is (i)non-toxic(biocompatible), (ii)moldable, (iii) self-hardening at a controlled and clinically suitable rate to allows a tight insertion into any bone defect (iv) biodegradable, (v)forms a porous material upon exposure to body biomimetic conditions, and (vi)displays both osteoinductive (silicatein)and osteoconductive (PMSA) properties.rnPreliminary in vivo experiments were carried out with rabbit femurs, by creatingrnartificial bone defects that were subsequently treated with the bifunctional 2-component implant material. After 9 weeks of implantation, both computed tomography (CT) and morphological analyses showed complete resorption of the implanted material, concurrent with complete bone regeneration. The given data can be considered as a significant contribution to the successful introduction of biosilica-based implants into the field of bone substitution surgery.

Computer aided design and finite element modeling to predict bulk mechanical properties of bone scaffolds using triply periodic minimal surfaces (progettazione assistita al calcolatore ed analisi con il metodo degli elementi finiti per predire il comportamento meccanico di scaffolds ossei creati con l'uso di superfici minime periodiche in tre direzioni)

The aim of Tissue Engineering is to develop biological substitutes that will restore lost morphological and functional features of diseased or damaged portions of organs. Recently computer-aided technology has received considerable attention in the area of tissue engineering and the advance of additive manufacture (AM) techniques has significantly improved control over the pore network architecture of tissue engineering scaffolds. To regenerate tissues more efficiently, an ideal scaffold should have appropriate porosity and pore structure. More sophisticated porous configurations with higher architectures of the pore network and scaffolding structures that mimic the intricate architecture and complexity of native organs and tissues are then required. This study adopts a macro-structural shape design approach to the production of open porous materials (Titanium foams), which utilizes spatial periodicity as a simple way to generate the models. From among various pore architectures which have been studied, this work simulated pore structure by triply-periodic minimal surfaces (TPMS) for the construction of tissue engineering scaffolds. TPMS are shown to be a versatile source of biomorphic scaffold design. A set of tissue scaffolds using the TPMS-based unit cell libraries was designed. TPMS-based Titanium foams were meant to be printed three dimensional with the relative predicted geometry, microstructure and consequently mechanical properties. Trough a finite element analysis (FEA) the mechanical properties of the designed scaffolds were determined in compression and analyzed in terms of their porosity and assemblies of unit cells. The purpose of this work was to investigate the mechanical performance of TPMS models trying to understand the best compromise between mechanical and geometrical requirements of the scaffolds. The intention was to predict the structural modulus in open porous materials via structural design of interconnected three-dimensional lattices, hence optimising geometrical properties. With the aid of FEA results, it is expected that the effective mechanical properties for the TPMS-based scaffold units can be used to design optimized scaffolds for tissue engineering applications. Regardless of the influence of fabrication method, it is desirable to calculate scaffold properties so that the effect of these properties on tissue regeneration may be better understood.

New Application of Piezoelectric Ultrasounds in Maxillo-facial bone surgery

Background: Piezoelectric instrumentation seems to offer 3 important advantages for cutting bone structures. Be more precise because it is produced by micro-vibrations from the cutting insert. Be safer because the ultrasonic frequency used does not affect soft tissue. Thirdly, the less invasive cutting action produces minor tissue damage and consequently probably a better healing Aim of the Study: The aim of this study is to evaluate the effectiveness of piezoelectric device capability in maxillo-facial surgery, in order to take advantage of these favourable capacity. Material and Methods: Considering the several potential application of the piezoelectric technology in Orthognathic, Oncologic and Extractive surgery, we would like to design protocols in order to verify how this new device can modify the surgical technique, the surgical time, the patients healing and its quality of life. Results: Due to the precise Piezosurgery cut, we can manage the Cad-Cam-Custom Made plates protocol in Oncologic Surgery and in Orthognatic Surgery increasing our percentage of comparison between the 3D preoperative plan and the surgical execution. We also found a better quality of life impaction in Patient who underwent and extractive surgery Conclusion: Piezosurgery device seems to be a strong surgical aid were safe and precise cut are needed and its capability to reduce the discomfort Patients need to be study in deep also in major surgery like Orthognatic and Oncologic surgery.