Use of supercharged cover screw as static magnetic field generator for bone healing, 2nd part: in vivo enhancement of bone regeneration in rabbits.

In 1979, Pulsed electromagnetic fields (PEMFs) were approved by the Food and Drug Administration as an effective method in the treatment of non-unions. As well as PEMFs, also static magnetic fields (SMFs) have been widely investigated in orthopaedic studies. Even if the exact mechanism of action is not well understood, a large number of studies showed specific effects both at cellular and tissue levels. As bone fracture healing and osseointegration share the same biological events, the application of magnetic field stimulation in order to facilitate the osseointegration process has been suggested. In this study we investigated BIC and newly formed bone volume around dental implants inserted in the tibia of New Zealand rabbits after SMF stimulation, generated by a small-customized cover-screw-shaped neodymium-iron-bore magnet placed in the inner cavity of dental implants. As a result, we found that the SMF field generated around dental implants enhanced bone healing in the animal model. Our findings represent, to our knowledge, the first ready clinical technique for dental implants showing the ability of SMF to promote the osteogenesis process in vivo.

Morphological analysis and interleukin release in human gingival fibroblasts seeded on different denture base acrylic resins.

The development of different types of materials with application in practice dentistry is an area of intense growth and research due to its importance in oral health. Among the diverse materials currently used in restoration or in dentures, the acrylic based resins have been widely employed. The release of toxic components and the changes on their physical and mechanical properties actually represent a goal of intensive research. In vivo analysis showed that the surface roughness of the acrylic resin represents a factor that could stimulate bacteria colonization and soft tissue inflammation. For this purpose, in this work, we have analyzed the cell response to acrylic based resins Ivoclar, Tokuso and Coldpack in basal conditions, unpolished, and after the polished procedure performed to reduce the surface roughness. Our in vitro results using human gingival fibroblasts (HGFs) showed a decrease of cell growth, evaluated by MTT assay starting at 24 h of incubation, in samples seeded on resins in basal conditions and after the polished procedure. This cell growth reduction was associated to evident morphological changes in unpolished materials. After 24 h of culture in presence of polished and unpolished resins a spontaneous release was present of pro-inflammatory cytokines such as interleukin-6 (IL-6) and -8 (IL-8), which was higher in unpolished resins, indicating that the polished procedure, minimizing the cytotoxicity process, could contribute to reduce the gingival inflammation processes.

Micromorphometrical and histological analyses using two different oscillating osteotomy techniques compared with conventional rotary osteotomy.

The recently introduced ultrasonic osteotome procedure is an alternative to conventional rotatory burs. The aim of this study was to establish the differences between two ultrasonic osteotomes and conventional rotatory burs, in order to perform micromorphological and histological analyses of osteotomized bone surfaces. Bony samples were taken from adult bovine ribs including both the cortical and marrow bone. Soft tissues have been removed and the bone pieces were divided into four groups, to test four devices: a conventional osteotomy round bur, a Lindeman bur and piezoelectric osteotomes ES007 and the T-Black. Each device performed cuts that were examined via scanning electron microscope (SEM) and light microscopy (LM) to check respectively cut precision and bone architecture all along the defect borders. SEM analysis of specimens showed that burs created defects of greater width and with irregular edges while those produced by ultrasonic osteotomes were narrow and had mostly smooth cutting surfaces. The edges of incisions made by drills were full of bone fragments while less bone chips were observed on piezoincision’s ones. Dimensions of fragments were wider if cuts were made by burs too. LM analysis of samples showed focally, delicate bony trabecules crushed and pressed into the bone marrow in cutting made by burs. Samples cut by ultrasonic devices showed small or no smear layer and only partial or no crushed trabecules. Osteocytes seemed to be intact all along the cutting surface in all samples observed. In the present study, according to literature, ultrasonic surgery validity is confirmed. As a matter of fact, the greater the number of bone chips products, the greater the magnitude of the inflammatory process induced, as well as the possibility of a greater bone loss and delay in wound healing near the osteotomized area.

The cytotoxic effects of resin-based sealers on dental pulp stem cells.

AIM: To evaluate the effect of four current resin-based adhesives on expanded ex vivo human dental pulp mesenchymal stem cells (DP-MSCs). METHODOLOGY: Dental pulp mesenchymal stem cells were derived from dental pulps of ten donors. After in vitro isolation, dental pulp stem cells were analysed using flow cytometry. The immunophenotype of DP-MSCs disclosed the homogeneous expression of the mesenchymal-related antigens CD29, CD44, CD73, CD90, CD105, CD166. DP-MSCs were exposed to four different commercially available bonding systems (CMF Bond, Prime&Bond NT, Clearfil S(3) Bond, XP Bond), and after 24, 48 and 72 h of incubation the morphological features and the cell growth were analysed. Moreover, the cell viability was evaluated at the same times by MTT assay. Data were statistically analysed using a two-way anova and Holm-Sidak method (alpha set at 0.05). RESULTS: Significant differences were observed between the four groups when comparing DP-MSCs appearance. DP-MSCs survived and proliferated without inhibition in the presence of CMF Bond adhesive. On the contrary, microscopic evaluation of the other three groups revealed extensive cytotoxic effects from the dentine bonding agents. The MTT assay revealed no statistically significant differences in cell viability after 72 h between the control group and CMF Bond group. All the other experimental groups had statistically lower optical density values. CONCLUSIONS: CMF Bond adhesive allowed human dental pulp stem cells to survive and proliferate. All of the other dentine bonding agents had extensive cytotoxic effects.

Comparative evaluation among laser-treated, machined, and sandblasted/acid-etched implant surfaces: an in vivo histologic analysis on sheep.

PURPOSE: The aim of the present in vivo analysis was to evaluate the osseointegration process of titanium implants with three different surfaces (machined, sandblasted and acid-etched, and laser-treated) after 15 and 30 days of healing period. MATERIALS AND METHODS: Thirty-six implants with different surfaces were placed in the iliac crest of four Bergamasca sheep. The implant surfaces tested were sandblasted and acid-etched (group A), laser-treated (group B), and fully machined (group C). Two animals were sacrificed after 15 days while the other two after 30 days. Histological and histomorphometric analyses were performed. RESULTS: After 30 days, the bone tissue layer onto implant groups A and B appeared almost continuous with small marrow spaces interruption, while on the machined surface (group C), larger spaces with marrow tissue alternated with the bony trabeculae onto the titanium surface. Implants in groups A and B showed significantly higher implant contact percentage (BIC%) value than group C (P < 0.05). Moreover, it was observed a BIC% increase in both groups A and B between 15 and 30 days while in the machined group (group C), the BIC% decreased. CONCLUSION: Results from the present in vivo analysis revealed that both sandblasted/acid-etched and laser-treated titanium implants, compared to the machined ones, have higher values of osseointegration in less healing time.

Effects of bur wear during implant site preparation: an in vitro study.

BACKGROUND: Few studies have investigated the influence of drilling on bone healing. After the drilling of bone and placement of dental implants a sequence begins of cellular and molecular events which represents a combined response of wound healing. The bone healing around dental implants is a complex phenomenon and influences the proliferation and differentiation of pre-osteoblasts into osteoblasts, together with the activation of periosteal and endosteal lining cells, and initiates the production and mineralization of osteoid matrix followed by the organization of the bone-implant interface. The objective of this study is to quantify the temperature changes in cortical bone and marrow spaces during implant site preparation in bovine rib bone. A total 10 harvested bovine ribs and 6 10.5 x 3.5 new drills for implant insertion with external irrigation (Bone System, Milano, Italy) were used in this study. The implant sites were prepared with 10 mm long drills at 500 rpm under abundant external irrigation with saline solution at 37 degrees C. Each drill was used for 10, 30, 60, 90 and 120 implant site preparations; each drill was then observed under SEM for evaluation of the damage of the cutting edge after 10, 30, 60, 90 and 120 preparations. There was an higher and statistically significant increase in the temperature in the cortical bone; this increase in temperature increases with the number of the times of drill use. The drill wear seemed to play a major role in heat production and could explain the observed increased temperature of the bone.

The performance of human periodontal ligament mesenchymal stem cells on xenogenic biomaterials.

Mesenchymal stem cells from periodontal ligament (PDL-MSCs) hold great promise for bone regeneration. Most studies regarding the osteogenic differentiation of stem cells from periodontal tissue suggest that PDL cells may have many osteoblast-like properties, including the ability to form calcified nodules in vitro. This study investigated the morphological and histochemistry aspects of human PDL-MSCs, induced for osteogenic differentiation and seeded on a xenogenic porcine bone substitute in vitro, at different times of incubation. This biomaterial seems physically identical to human bone, and it has been reported to be osteoconductive. Our results indicated that the cells had a high affinity for the three-dimensional biomaterials; in fact, cellular proliferation and colonization was evident, and after 21 days the adherent cells started to detach themselves from the substrate, and at 30 days of incubation in differentiation medium, the cells completely lost the adhesion to the Petri's disk, englobing all bioparticles. In conclusion, the in vitro behaviour of PDL-MSCs and their relationship with three-dimensional scaffold biomaterials encourage in vivo investigations for their use in dental tissue regeneration.

Dental pulp stem cells bioadhesivity: evaluation on mineral-trioxide-aggregate.

Stem cells are undifferentiated cells that have the capacity to self-renew. They have been discovered in many adult tissues, including teeth. Dental Pulp Mesenchymal Stem Cells (DP-MSCs) are involved in dental repair by activation of growth factors, released after caries and have the ability to regenerate a dentin-pulp-like complex. The molecular/cellular research gives the possibility to grow new tissues and biological structures for clinical applications, providing cells for therapies including cell transplantation and tissue engineering. In this study DP-MSCs were derived from dental pulp of 10 donors. To evaluate material toxicity, after in vitro isolation, the cells were seeded on mineral trioxide aggregate (MTA). Initial light microscopy investigation of cells revealed no signs of cell death due to toxicity or infection, on the contrary the scaffolds supplied an excellent support for cell structures, the cells proliferated and adhered to substrate. Similar observation was seen in scanning electron microscopy, in particular the cells had proliferated and spread, covering a considerable part of the surface of the biomaterials investigated, with an elaborate form of attachment, in fact, the cells formed a continuous layer on the upper surface of the MTA. In conclusion, the aim of this study is to demonstrate that DP-MSCs combined with MTA could be a potential source for regenerative medicine, encouraging further study to evaluate the new dentin formation.

[Castleman disease with lateral neck outset. Report of a clinical case]. / Malattia di Castleman ad esordio laterocervicale. Descrizione di un caso clinico.

This work presents the case of a young woman with Castleman's disease, manifest as an isolated, asymptomatic swelling in the supraclavear fossae. A fine needle biopsy was performed on the swelling and cytology on this material proved insignificant (blood cells), while CT and MRI did not show any significant vascular components nor did they provide any elements decisive for diagnosis, the neoformation being similar to a reactive lymph node. To determine the nature of the mass, the lesion was removed by cervicotomy. Histology then led to a definitive diagnosis of a hyaline vascular variant of Castleman's disease. The literature on the topic was then reviewed with an eye to otorhinolaryngological manifestations and the histological aspects and clinical-diagnostic approach are discussed in detail.

[Marginal adaptation after cementing of gold inlays cast by an experimental procedure. SEM analysis]. / Adattamento marginale dopo cementazione di intarsi in oro fusi con una metodica sperimentale. Analisi al SEM.

AIM: Marginal adaptation is one of the most important factors in dental reconstructions. The aim of the present work was to evaluate with in vivo and in vitro studies the marginal precision and the microstructure of the gold cast inlays. METHODS: For the in vivo analysis 10 patients were selected, while for the in vitro study 10 extracted teeth were used. The impressions were made by polyvinylsiloxane while the master cast was made by gypsum type IV. The inlays were cast in gold (JRVT Jensen) using an experimental procedure. After cementing, the margins of each inlay was burnished. To evaluate the marginal discrepancy of in vivo inlays, the replica technique was used, while for the in vitro analysis the serial slice cut technique was performed. All samples were processed for metallographic analysis using SEM. RESULTS: The measured in vivo inlay marginal gap was 9,06+/-3,37 microns (mean+/-SD), while for in vitro inlay the marginal gap was of 10,47+/-2,09 microns (mean+/-SD). Metallographic analysis showed equiaxial grain of small dimension. CONCLUSIONS: The results suggest that using the proposed casting technique it is possible to increase marginal adaptation and microstructural properties.

Residual and inflammatory radicular cysts. Clinical and pathological aspects of 2 cases.

Inflammatory odontogenic cysts include radicular cysts and its etiological variance, residual cysts. Among these lesions, the radicular cyst is the most frequent. It is caused by the growth of remnants of Malassez cells involved in the development of the dental organ. Clinically, radicular cysts are difficult to diagnose. Histologic diagnosis is of primary importance in order to definitely discriminate the different kinds of periapical lesions. In this paper, the clinical, radiographic, etio-physio-pathological and microscopic features of these pathological formations are described. A case of a large radicular cyst and a case of residual cyst are reported and the surgical treatment and histologic differential diagnosis are presented.

Regenerative potential of human periodontal ligament derived stem cells on three-dimensional biomaterials: a morphological report.

Recent studies have shown that mesenchymal stem cells obtained from periodontal ligament (PDL-MSCs) are multipotent cells that have similar features of the bone marrow and dental pulp MSCs and are capable of proliferating and producing different types of tissue such as bone and tooth associated-tissues. Human PDL-MSCs expanded ex vivo were induced to osteogenesis, seeded in three-dimensional biocompatible scaffolds (fibrin sponge, bovine-derived substitutes) and examined using light, scanning and transmission electron microscopy. Morphological observations showed extensive growth of cellular biomass partially covering the scaffolds after 4 weeks of incubation in mineralization medium. These findings indicate that periodontal ligament can be an easily and efficient autologous source of stem cells with a high expansion capacity and ability to differentiate in osteogenic cells that can colonize and grow connected to bio-compatible scaffold. It can be suggested that the use of PDL-MSCs for generating graft biomaterials is advantageous for bone tissue engineering in regenerative dentistry.

A survey of primary care physician practice patterns and adherence to acute low back problem guidelines.

OBJECTIVE: This study evaluated physicians' self-reported management of acute low back problems in adults and adherence with published guidelines. DESIGN: Self-administered written survey based on the US Agency for Health Care Policy and Research (now the Agency for Healthcare Research and Quality) guideline on acute low back problems in adults. SETTING: A region of northern Illinois with a population around 250 000 and encompassing a medium-sized city. PARTICIPANTS: One hundred eighty-two primary care physicians (nonpediatric) with medical staff appointments at area hospitals. MAIN OUTCOME MEASURE: Adherence to published recommendations. RESULTS: Eighty-seven surveys were received for a 48% response rate. Overall, survey respondents recognized 5 of 7 red flags representing serious underlying abnormality 50% or less of the time. Forty percent (35/87) of physicians provided patients with written educational material, and only 25%(22/87) indicated they evaluated motor function of the fifth lumbar nerve, the most commonly affected level in intervertebral disk disease disease. About 25% (24/87) reported routine use of plain films; and 16% (14/87), routine use of computed tomography or magnetic resonance imaging. Most oral medication use was consistent with recommendations, but many also used drugs conditionally discouraged by the guideline (muscle relaxants, 91% [79/87]; opioids, 62% [54/87]) or cautioned against (oral steroids, 45% [39/87]; antidepressants, 23% [20/87]; injection therapy, 52% [45/87]). Only 22% (19/87) of respondents used or recommended manipulation. CONCLUSIONS: The management of patients with acute low back problems by primary care physicians differs significantly from Agency for Health Care Policy and Research guideline recommendations in several key areas that include awareness of red flags, use of medication, use of radiographic studies, the need for patient education, and the use of physical modalities. Future research should focus on the impact of guideline compliance on patient outcomes and cost-effectiveness. Arch Fam Med. 2000;9:1015-1021