1,721,032 research outputs found
The effect of glycine-powder airflow and hand instrumentation on peri-implant soft tissues: a split-mouth pilot study.
No full textFifteen edentulous patients with overdentures supported by two implants in the mandibular canine regions received periodontal therapy using both hand instrumentation with Teflon curettes and a glycine-based airflow system. Periodontal probing depth (PPD), bleeding on probing (BOP), and bacterial content (BC) within the gingival sulcus were analyzed. A significant effect modification of the glycine airflow with respect to time was found for PPD (P = .01), BOP (P < .001), and BC (P = .004), which were treated as ordered categorical variables. Glycine airflow may be more effective than Teflon curettes for the maintenance of periimplant soft tissues
AlNx and a-SiOx coatings with corrosion resistance properties for dental implants
No full textAluminium nitride thin films were deposited on titanium fixtures, while silicon oxide thin films were deposited on titanium fixtures and chromium–cobalt substrates, using the RF magnetron sputtering technique. Each coating showed different corrosion behaviours when electrochemical characterisations were
made in a simulated biological environment, i.e. Hank's solution. Although aluminium nitride was more effective in reducing the localised corrosion on titanium implants, silicon oxide showed the best behaviour against general corrosion and results were consistent for the two kinds of substrates. Moreover the application of a SiO2/AlN bilayer onto the Ti fixtures improved the performances of each separate coating. When the coated surfaces were compared to uncoated substrates, there was no statistically significant difference in cell viability in the response of two different human osteoblastic cell lines — Saos-2 and MG-63. Field emission scanning electron microscopy assessed the surface morphology of coated and uncoated samples, whilst Fourier transform infrared spectroscopy was applied to investigate the bonding structure of barrier layers on silicon samples. On the basis of the data obtained, we are of the opinion that the tested
materials show some promising characteristics for the fabrication of novel dental implants with reduced ion release properties
Bone morphogenetic proteins and bone defects - A systematic review
No full textSTUDY DESIGN:
A systematic review of scientific literature.
OBJECTIVE:
The study aimed to determine whether bone morphogenetic proteins (BMPs) are more effective in treating bone defects than traditional techniques, such as grafting autologous bone.
SUMMARY OF BACKGROUND DATA:
BMPs were used in several human randomized controlled trials (RCTs). There are both logical arguments and an empirical basis for using RCTs to evaluate the effects of health care interventions and restrict systematic reviews to such a kind of study design.
METHODS:
An electronic search was made in the databases of MEDLINE, EMBASE (through MeSH and Emtree), and the Cochrane Central Register of Controlled Trials, extended to May 31, 2006, with no linguistic restrictions. RCTs that compare bone regeneration achieved through BMPs versus that obtained by traditional methods entered the study.
RESULTS:
The 17 publications that met the criteria, divided into subgroups by type of bone, were tabulated by salient characteristics and evaluated through the items proposed by van Tulder et al. However, as the studies differed widely (in terms of site, sample size, dosage of active principle, carrier, clinical and radiologic data recording), it was possible to carry out a metaanalysis of clinical and radiologic outcome only for the subgroup that evaluated the vertebrae, where it was observed that BMPs offer a slightly but statistically significant greater efficacy than do traditional techniques.
CONCLUSIONS:
The use of BMPs at the vertebrae can eliminate the need for surgery to harvest autologous bone. The only large study carried out on the other sites suggests that BMPs should be used at a concentration of 1.5 mg/mL to treat fractures of the tibia. However, further RCTs of good methodological quality are advisable so as to clarify the effectiveness of BMPs in clinical practice
Reduction of bacterial adhesion on dental composite resins by silicon-oxygen thin film coatings
No full textAdhesion of bacteria on dental materials can be reduced by modifying the physical and chemical characteristics of their surfaces, either through the application of specific surface treatments or by the deposition of thin film coatings. Since this approach does not rely on the use of drugs or antimicrobial agents embedded in the materials, its duration is not limited by their possible depletion. Moreover it avoids the risks related to possible cytotoxic effects elicited by antibacterial substances released from the surface and diffused in the surrounding tissues. In this work, the adhesion of Streptococcus mutans and Streptococcus mitis was studied on four composite resins,
commonly used for manufacturing dental prostheses. The surfaces of dental materials were modified
through the deposition of a-SiO x thin films by plasma enhanced chemical vapor deposition.
The chemical bonding structure of the coatings was analyzed by Fourier-transform infrared
spectroscopy. The morphology of the dental materials before and after the coating deposition was
assessed by means of optical microscopy and high-resolution mechanical profilometry, while their
wettability was investigated by contact angle measurements. The sample roughness was not altered
after coating deposition, while a noticeable increase of wettability was detected for all the samples.
Also, the adhesion of S. mitis decreased in a statistically significant way on the coated samples, when
compared to the uncoated ones, which did not occur for S. mutans. Within the limitations of this
study, a-SiO x coatings may affect the adhesion of bacteria such as S. mitis, possibly by changing the
wettability of the composite resins investigated
a-SiOx coatings grown on dental materials by PECVD: compositional analysis and preliminary investigation of biocompatibility improvements
No full textSi-Based Amorphous Thin Films for the Performance Improvement of Dental Prostheses and Implants
No full textIt is well known that determining the physico-chemical surface properties of both dental and intrabony prostheses is a powerful means that may help elucidating some fundamental features of the interface between the recipient tissues and the prosthesis itself. When dealing with dental prostheses (total dentures, fixed dental prostheses, partial removable dental prostheses), a continuous contact with different tissues and body fluids is required for their different parts. Indeed roughness, porosity and surface energy, as well as surface elemental composition, will strongly influence the response of the tissues, eventually contributing to the success or fail of the prosthesis. This is even more true for the implant-supported fixed dental prostheses, where an intra-bony part, i.e. the dental implant, is connected through a transmucous structure, i.e. the implant abutment, to the intraoral part, i.e. the fixed prosthesis. Thus the same titanium material is supposed to enhance both bone and epithelial healing, whilst the intraoral framework and artificial teeth –which may be made by several different materials- are to avoid bacterial adhesion as much as possible. Several surface modification processes are currently used in order to improve the prostheses performances, but many of them are still not completely satisfactory, and a continuous research effort is still required to improve their effectiveness. In this chapter, we describe the use of silicon-based amorphous thin film alloys to improve the performances of dental prostheses and implants. Indeed,
hydrogenated amorphous silicon-based alloys, such as amorphous hydrogenated silicon-oxygen (a-SiOx:H) alloys possess interesting properties, which can be exploited for the surface modification of dental prostheses and implants. They are inert and largely biocompatible materials and do not embed dangerous metallic elements, such as Ni, Al, Cr, or Mo, which could be released into the body during the long term contact within living tissues. Moreover, the hydrogen incorporation, which is typical of amorphous material grown by plasma-assisted CVD techniques, has already been proven helpful in enhancing the biocompatibility of silicon and silicon-based materials. We studied the effects of amorphous silicon-based alloys for the performance improvement of several bulk materials used for the fabrication of prostheses and implants, including ceramics, resins, titanium and cobalt-chromium alloys. The films showed interesting properties as for the bacterial adhesion reduction, the biocompatibility improvement and the corrosion protection of bulk materials under study
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Proanthocyanidin may improve the shear bond strength at the composites/dentine interface
No full textThis study aimed at assessing whether proanthocyanidin, a collagen cross-linker, affects the adhesion strength of resin composites on the dentine surface. Freshly extracted, caries-free, human molars (N=55) were embedded in transparent resin and bisected. The halves were then assigned to either a treated or a non-treated group, where the treatment consisted of a 10 min incubation in a 6.5% proanthocyanidin solution in PBS. A resin composite cylinder was polymerized perpendicularly to the dentinal surfaces and shear tests were made, using an Instron-like machine. The fracture surfaces were characterized by optical (Picro-Sirius Red stain) and electron microscopy (FESEM EDX analysis). Mean bond strength values were 10.73 MPa (SD 3.70) for the treated group and 8.69 MPa (SD 3.20) for the non-treated group (p less than 0.05 Students t-test). No constant fracture patterns could be found within the two groups. Proanthocyanidin treatment may improve the adhesion properties of the dentine-bonding interface
Plasma of Argon Affects the Earliest Biological Response of Different Implant Surfaces
No full textThe aim of this in vitro study was to evaluate the early cell response and protein adsorption elicited by the argon plasma treatment of different commercially available titanium surfaces via a chair-side device. Sterile disks made of grade 4 titanium (n = 450, 4-mm diameter) with 3 surface topographies (machined, plasma sprayed, and zirconia blasted and acid etched) were allocated to receive 4 testing treatments (2% and 10% protein adsorption and cell adhesion with MC3T3-E1 and MG-63). Furthermore, the specimens were divided to undergo 1) argon plasma treatment (10 W, 1 bar for 12 min) in a plasma reactor, 2) ultraviolet (UV) light treatment for 2 h (positive control group), or 3) no treatment (control group). Pretreatment surface analyses based on a scanning electron microscope and profilometer images were also performed. Profilometric analysis demonstrated that the evaluated specimens perfectly suit the standard parameters. The use of argon plasma was capable of affecting the quantity of proteins adsorbed on the different surfaces, notwithstanding their roughness or topographic features at a low fetal bovine serum concentration (2%). UV light treatment for 2 h attained similar results. Moreover, both the plasma of argon and the UV light demonstrated a significant increase in the number of osteoblasts adherent at 10 min in all tested surfaces. Within its limitations, this in vitro study highlights the potential biological benefits of treating implant surfaces with plasma of argon or UV, irrespective of the roughness of the titanium surface. However, in vivo experiments are needed to confirm these preliminary data and settle the rationale of a treatment that might be clinically relevant in case of bone-reparative deficiencies
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