99 research outputs found
Histological and fluorescence microscopic examination of the bone/implant interface in orthodontic miniscrews (Mondeal®)
The temporary nature of orthodontic implants demands optimisation of size
and design in order to minimise damage and risk to the patient. Slender and
shorter miniscrews offer the advantage over conventional implants of easier and
more ubiquitous positioning with minimised risk of injury to neighbouring anatomical
structures such as tooth roots, nerves or vessels. The question is raised,
however, as to what extent these advantages are gained at the price of diminished
stability or a more unfavourable bone interface. In order to evaluate the
screw/bone interface, 14 orthodontic miniscrews (Mondeal Medical Systems,
diameter: 1.5 mm, length: 9 mm) were inserted into the right and left mandibles
of 7 pigs (Sus scrofa domestica). Bone fluorochromes were administered in
a defined order for polychrome sequencing. The samples gathered after 70 days
were analysed using histological techniques and fluorescence microscopy. The
lower part of the self-tapping thread displayed undisturbed bone apposition.
Fluorescence microscopy revealed remodelling and bone apposition within the
thread grooves
The morphological and clinical relevance of mandibular and maxillary bone structures for implantation
Tooth loss, which interrupts the biocybernetic feedback circuit of the masticatory
system, changes the structures of the jaw bone: such changes are termed
"inactivity atrophy". The mandible is subject to vertical atrophy and the maxilla is
primarily subject to horizontal atrophy. The mandible possesses more compact
bone, the maxilla more spongy; the resorption directions also differ (mandible:
towards the oral aspect; maxilla: towards the vestibular). An implant helps to
restore the biocybernetic feedback system. The amount of available bone, bone
structure, and topographic conditions are crucial factors influencing implant
success. Osseointegration is performed at an early stage (which includes bleeding,
granulation tissue, foreign-body recognition, interactions) and at a late stage
(so-called osseous bridging, development of fibrous and lamellar bone)
The use of ceramic drills on a zirconium oxide basis in bone preparation
The favourable mechanical properties and high biocompatibility of the newly
developed mixed ceramics composed of zirconium oxide and aluminium oxide
have continuously extended the scope of their application. Rotating instruments
on a zirconium oxide basis are regarded as superior to metal burs in dentoalveolar
surgery in terms of favourable temperature effects on the surrounding bone
tissue and the economic advantage that they wear slowly, enabling them to be
used repeatedly. In this study ten round burs made of zirconium oxide and
aluminium oxide mixed ceramics were used for typical dental-alveolar preparation
types on an explanted pig jaw. Prior to the first and following the tenth application
a scanning electron microscopic (SEM) analysis of possible wear signs was conducted.
However, this revealed no evidence of wear or resulting loss of sharpness
Bacterial colonisation of interior implant threads with and without sealing
Premature loss of dental implants is due, apart from mechanical factors, to germrelated
inflammation. Gaps and hollow spaces within the implant system, for
example the gap between implant and abutment in the two-part implant system,
may provide a bacterial reservoir causing or maintaining inflammation. The
bacterial spectrum involved is similar to that found in periodontitis.
This in vitro study aimed to scrutinise the capability of Porphyromonas gingivalis
(DSM 20709), the bacterium blamed for inducing peri-implantitis, to pass the
implant/abutment gap in titanium implant systems used for orthodontic anchorage
and to remain vital in the interior. Additionally, the in vitro effectiveness of
gutta percha for gap sealing was examined. Twelve titanium implants (Straumann
®, diameter: 3.3 mm, length 5.5 mm) were provided with abutments at
a defined torque (20 Ncm), six of which were sealed with gutta percha before
screwing in the abutment. Subsequently the implants were placed in a nutrient
solution (thioglycolate boullion with haemin-menadione solution) that contained
Porphyromonas gingivalis. Microbiological specimens were sampled from the
implant interiors after 24 and 72 hours and analysed using culture methods.
There was evidence that penetration of the periodontal pathogen Porphyromonas
gingivalis to the implant interior may occur as early as after 24 hours. Microbes
were also detected in the interior of implants sealed with gutta percha.
The abutment/implant interface in vitro provides a microbiological leakage for
the prospective peri-implantitis-inducing bacterium Porphyromonas gingivalis.
Survival of the bacterium is possible in the interior, so that development of
a bacterial reservoir is assumed. This in vitro trial produced no evidence that
sealing with gutta percha is an effective means to prevent secondary bacterial
colonisation in the implant interior
Requirements and infection prophylaxis for internally cooled implant drills
Implant site preparation is crucially important to long-term success. Heat generation
during drilling is unfavourable, since bone is relatively susceptible to heat,
depending on its vascularisation and microstructure. Numerous factors such as
drilling pressure, number of revolutions, drill design, wear and material, drilling
depth and cooling influence heat generation. Internally cooled drills are, therefore,
increasingly used, even though the improved cooling effect compared to
conventional externally cooled drills is controversial. Internally cooled drills may
have the disadvantage of a germ reservoir developing in the cooling channel.
This study aimed to examine the effects of disinfection and sterilisation of internally
cooled drills. After contamination of the cooling channel with suitable bioindicators
(Enterococcus faecium, ATCC 6057 and spores of Bacillus stearothermophilus,
ATCC 7953), the drills were disinfected (disinfection solution ID 220,
Dürr Dental) and autoclaved (Webeco, E5S90, 134°C, 2.6 bar, 5 min). Disinfection
was not completely effective except after pre-cleaning. By means of sterilisation
all spores of Bacillus stearothermophilus were completely killed. Internally
cooled drills can be successfully disinfected by means of this hygienic procedure
routinely used in dental practice and no source of infection is created
The survival and proliferation of fibroblasts on orthodontic miniscrews with different surface treatment: an in vitro study
It is of fundamental importance for prosthodontic and orthodontic applications
that there is a short osseointegration time of dental implants without inflammation
of the surrounding tissue. In addition to the chemical properties of the
implant material, the surface morphology is an equally critical parameter. The
objective of this work was to study the effect of two simple surface treatments
on the survival and proliferation of fibroblasts.
Three groups of orthodontic miniscrews (Mondeal®) were used. One group was
given an airflow (EMS, Schweiz) treatment, the second was sand-blasted in the
area of the threading and a third group served as a control. After preparation
sterilised screws were cultured in vitro with fibroblasts (L-929). The metabolic
cell activity on the implant surface was determined after 24, 48 and 120 hours
using the alamarBlue assay and a count of DAPI labelled fibroblasts was performed
with a fluorescence microscope.
After 24 hours, but not at 48 hours and 120 hours, the metabolic activity of the
fibroblasts was slightly decreased for the airflow screw group. Generally, no
significant difference was found regarding metabolic activity and proliferation
of fibroblasts within the different groups
Annual Report 2013 / Institute for Nuclear Waste Disposal. (KIT Scientific Reports ; 7664)
The contributions collected in this report provide a representative overview of the scientific outcome of INE research activities in 2013. The structure of the report follows widely the organization of the institute according to research topics: basic research towards understanding geochemical reactions of radionuclides on a molecular scale and applied studies on radionuclide retention in multi-barrier system under real repository conditions
Sorption of Am(III) onto 6-line-ferrihydrite and its alteration products: investigations by EXAFS
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