Particle motion observed during offshore wind turbine piling operation.

Measurement of particle motion from an offshore piling event in the North was conducted to determine noise levels. For this purpose, a bespoken sensor was developed that was both autonomous and sensitive up to 2 kHz. The measurement was undertaken both for unmitigated and mitigated piling. Three different types of mitigation techniques were employed. The acceleration zero-to-peak values and the acceleration exposure levels were determined. The results show that inferred mitigation techniques reduce the levels significantly as well as decreases the power content of higher frequencies. These results suggest that mitigation has an effect and will reduce the effect ranges of impact on marine species.

Spatial and Temporal Variability of Ambient Underwater Sound in the Baltic Sea.

During last decades, anthropogenic underwater sound and its chronic impact on marine species have been recognised as an environmental protection challenge. At the same time, studies on the spatial and temporal variability of ambient sound, and how it is affected by biotic, abiotic and anthropogenic factors are lacking. This paper presents analysis of a large-scale and long-term underwater sound monitoring in the Baltic Sea. Throughout the year 2014, sound was monitored in 36 Baltic Sea locations. Selected locations covered different natural conditions and ship traffic intensities. The 63 Hz, 125 Hz and 2 kHz one-third octave band sound pressure levels were calculated and analysed. The levels varied significantly from one monitoring location to another. The annual median sound pressure level of the quietest and the loudest location differed almost 50 dB in the 63 Hz one-third octave band. Largest difference in the monthly medians was 15 dB in 63 Hz one-third octave band. The same monitoring locations annual estimated probability density functions for two yearly periods show strong similarity. The data variability grows as the averaging time period is reduced. Maritime traffic elevates the ambient sound levels in many areas of the Baltic Sea during extensive time periods.

Application of a Monte Carlo method to the uncertainty assessment in in situ gamma-ray spectrometry.

In situ gamma-ray spectrometry has since the introduction of portable germanium detectors been a widely used method for the assessment of radionuclide ground deposition activity levels. It is, however, a method that is most often associated with fairly large and, more important, poorly known combined measurement uncertainties. In this work an uncertainty analysis of in situ gamma ray spectrometry in accordance with the Guide to the Expression of Uncertainty in Measurements is presented. The uncertainty analysis takes into account uncertainty contributions from the calibration of the detector system, the assumed activity distribution in soil, soil density, detector height and air density. As a result, measurement results from in situ gamma spectrometry will serve as a better basis for decision-making in e.g. radiological emergencies.

A generic emission model to predict release of organic substances from materials in consumer goods.

Organic chemicals may be released when consumer goods are used, contributing to environmental and human levels of potentially hazardous chemicals. A generic model was developed to predict emissions of organic chemicals from various materials in consumer products. The model involved three modules, which each predict a key parameter needed to calculate the mass of individual chemicals emitted. Partition coefficients between a material and the surrounding air were predicted using Abraham solvation parameters, diffusion coefficients in materials were calculated using the Piringer equation, and convective mass transfer coefficients were evaluated by applying the Chilton-Colburn analogy. The calculated emission rates from predicted parameters were evaluated and agreed well with literature data. The release of plasticizers from vinyl flooring used in Sweden was calculated to demonstrate the utility of the generic model. The estimated emitted masses of di(2-ethylhexyl)phthalate (DEHP), di-iso-nonylphthalate (DINP), and 1,2-cyclohexanedicarboxylic acid di-iso-nonyl ester (DINCH) in 2012 were 210 kg, 40 kg, and 3.6 kg respectively. Emissions from vinyl flooring were estimated for the period 1990 to 2035 and it was shown that the recent substitution of DEHP with DINP will help to reduce plasticizer emissions. Model calculations for alternative plasticizers revealed that DINCH would yield similar emissions to DINP, whereas use of diethyl hexyl-iso-sorbide or diethyl hexyl adipate would result in higher emissions.

Implant surface characteristics influence the outcome of treatment of peri-implantitis: an experimental study in dogs.

AIM: To analyse the effect of surgical treatment of peri-implantitis without systemic antibiotics at different types of implants. MATERIAL AND METHODS: Four implants representing four different implant systems - turned (Biomet 3i), TiOblast (Astra Tech AB), SLA (Straumann AG) and TiUnite (Nobel Biocare AB) were placed in the left side of the mandible in six dogs, 3 months after tooth extraction. Experimental peri-implantitis was initiated by placement of ligatures and plaque formation. The ligatures were removed when about 40-50% of the supporting bone was lost. Four weeks later, surgical therapy including mechanical cleaning of implant surfaces was performed. No systemic antibiotics or local chemical antimicrobial therapy were used. After 5 months, block biopsies were obtained and prepared for histological analysis. RESULTS: Two of the TiUnite implants were lost after surgical therapy. Radiographic bone gain occurred at implants with turned, TiOblast and SLA surfaces, while at TiUnite implants additional bone loss was found after treatment. Resolution of peri-implantitis was achieved in tissues surrounding implants with turned and TiOblast surfaces. CONCLUSION: Resolution of peri-implantitis following treatment without systemic or local antimicrobial therapy is possible but the outcome of treatment is influenced by implant surface characteristics.

Spontaneous progression of ligatured induced peri-implantitis at implants with different surface characteristics. An experimental study in dogs II: histological observations.

AIM: The aim of the present study was to analyze tissue reactions to plaque formation following ligature removal in experimental peri-implantitis at commercially available implants in dogs. MATERIAL AND METHODS: Mandibular premolars and the three anterior premolars in both sides of the maxilla were extracted in six Labrador dogs. After 3 months, four implants representing four different implant systems--groups A (turned), B (TiOblast), C (SLA), D (TiUnite)--were placed in a randomized order in the right side of the mandible. Three months after implant installation, experimental peri-implantitis was initiated by placement of ligatures and plaque formation. The ligatures were removed when about 40-50% of the supporting bone was lost. After the subsequent 24-week period of continued plaque accumulation, block biopsies containing implants and their surrounding tissues were obtained and prepared for histological analysis. RESULTS: All types of implants exhibited extensive inflammatory cell infiltrates and large associated crater-formed osseous defects. The lesions were consistently characterized by insufficient encapsulation of pus and biofilm layers and the inflammatory cell infiltrates extended apical of the pocket epithelium. The presence of numerous osteoclasts indicated active tissue destruction. The vertical dimension and the overall surface area of the infiltrated connective tissue (ICT) were larger at implants of group D than at other implant types. CONCLUSION: It is suggested that spontaneous progression of peri-implantitis is associated with severe inflammation and tissue destruction.

Spontaneous progression of peri-implantitis at different types of implants. An experimental study in dogs. I: clinical and radiographic observations.

AIM: The aim of the present study was to analyze tissue reactions to plaque formation following ligature removal at commercially available implants exposed to experimental peri-implantitis. MATERIAL AND METHODS: Six Labrador dogs about 1 year old were used. All mandibular premolars and the three anterior premolars in both sides of the maxilla were extracted. After 3 months four implants representing four different implant systems with different surface characteristics--implant group A (turned), B (TiOblast), C (sandblasted acid-etched; SLA) and D (TiUnite)--were placed in a randomized order in the right side of the mandible. Three months after implant installation experimental peri-implantitis was initiated by placement of ligatures in a submarginal position and plaque accumulation. At week 12, when about 40-50% of the supporting bone was lost, the ligatures were removed. During the subsequent 24-week period plaque accumulation continued. Radiographic and clinical examinations were performed during the 'active breakdown' period (plaque accumulation and ligatures) and the plaque accumulation period after ligature removal. The experiment was terminated at week 36. RESULTS: The bone loss that took place during the 'active breakdown' period varied between 3.5 and 4.6 mm. The additional bone loss that occurred during the plaque accumulation period after ligature removal was 1.84 (A), 1.72 (B), 1.55 (C) and 2.78 mm (D). CONCLUSION: Spontaneous progression of experimentally induced peri-implantitis occurred at implants with different geometry and surface characteristics. Progression was most pronounced at implants of type D (TiUnite surface).

Bone tissue formation adjacent to implants placed in fresh extraction sockets: an experimental study in dogs.

OBJECTIVE: To study the healing of marginal defects that occurred at implants placed in a healed ridge or in fresh extraction sockets. MATERIAL AND METHODS: Six dogs were used. The right side of the mandible was used in the first part of the study. The first, second premolars and first molars were extracted. After 3 months of healing the bone was prepared for implant installation in these premolar and molar sites. The marginal 5 mm of each recipient site was widened with a conical drill. Following implant installation a gap of varying dimension occurred around the titanium rod (artificial defect (A) sites). At this interval the third and fourth premolars were extracted and implants were installed in the distal socket of the two teeth (natural defect (N) sites). The flaps were sutured to allow non-submerged healing. After 2 months, the procedures were repeated in the left side. Two months later the animals were euthanized, and biopsies were obtained and prepared for histological examination. RESULTS: The length of the zone of de novo'bone-to-implant contact' in the defect region was longer at the A sites than at the N sites both at the 2- and the 4-month interval. Further, while after 4 months of healing the marginal bone crest at the A sites was located close to the abutment/fixture junction, at the N sites a marked reduction of the height of the bone crest was documented. Hence, most A site defects became completely resolved whereas healing of the N site defects was incomplete. CONCLUSION: The process of bone modeling and remodeling at an implant placed in a fresh extraction socket differs from the resolution of marginal defects that may occur following implant installation in a healed ridge.

Implant stability during initiation and resolution of experimental periimplantitis: an experimental study in the dog.

BACKGROUND: Histologic studies have demonstrated the possibility to reestablish direct bone-implant contacts after ligature-induced periimplantitis. The influence of the reosseointegration on the stability of implants is not known. PURPOSE: The aim of the present investigation was to study bone tissue and associated implant stability alterations that occurred during induction and resolution of periimplantitis using resonance frequency analysis (RFA), radiography, and histology. MATERIALS AND METHODS: Three implants with smooth (turned) or roughened (SLA) surfaces were placed in each side of the edentulous mandible of four dogs. Experimental periimplantitis was induced for 3 months. Five weeks later, the animals were treated with antibiotics and surgical therapy and were followed for another 6 months. Periapical radiographs and RFA were used to evaluate marginal bone levels and implant stability throughout the study period. After termination, the tissue-implant interface was evaluated by light microscopy in ground sections. RESULTS: There was a linear relationship between radiographic and RFA findings because continuous loss of marginal bone and a decrease in implant stability were observed for both implant surfaces during the periimplantitis period. Antibiotic treatment and surgical therapy resulted in some reosseointegration, which was more marked for the SLA surface. The resonance frequency values corresponded well to the histometric measurements because reosseointegration resulted in an increase in implant stability. CONCLUSIONS: The findings from the present study indicate a linear relationship between marginal bone level and resonance frequency value. It is suggested that the RFA technique is sensitive and may be used to detect even a minor change in the level of bone-implant contact.

Bone regeneration at implants with turned or rough surfaces in self-contained defects. An experimental study in the dog.

BACKGROUND: Marginal hard tissue defects present at implants with a rough surface can heal with a high degree of bone fill and osseointegration. The healing of similar defects adjacent to implants with a smooth surface appears to be less predictable. OBJECTIVE: The aim was to compare bone healing at implants with turned or rough surface topographies placed in self-contained defects using either a submerged or non-submerged installation technique. MATERIAL AND METHODS: Six dogs were used. Three months after tooth extraction four experimental sites were prepared for implant installation in both sides of the mandible. The marginal 5 mm of the canal prepared for the implant was widened. Thus, following implant placement a circumferential gap occurred between the bone tissue and the implant surface that was between 1 and 1.25 mm wide. In each side of the mandible two implants with a turned surface and two implants with a rough surface were installed. The implants in the right side were fully submerged, while a non-submerged technique was applied in the left side. The animals were sacrificed 4 months later, block biopsies of each implant site were dissected and ground as well as paraffin sections were prepared. RESULTS: The marginal defects around rough surface implants exhibited after 4 months of healing substantial bone fill and a high degree of osseointegration following either the submerged or the non-submerged installation technique. Healing at turned implants was characterized by incomplete bone fill and the presence of a connective tissue zone between the implant and the newly formed bone. The distance between the implant margin (M) and the most coronal level of bone-to-implant contact (B) at implants with a rough surface was 0.84+/-0.37 mm at submerged and 0.90+/-0.39 mm at non-submerged sites. The distance M-B at implants with a turned surface was 3.39+/-0.52 mm at submerged and 3.23+/-0.68 mm at non-submerged sites. The differences between the rough and turned implants regarding the length of distance M-B were statistically significant (paired t-test). CONCLUSION: Osseointegration at implants placed in sites with marginal defects is influenced by the surface characteristics of the implant.

Carbon dioxide laser and hydrogen peroxide conditioning in the treatment of periimplantitis: an experimental study in the dog.

BACKGROUND: Various methods have been applied for the treatment of periimplantitis lesions. It has been reported that the procedures used have been effective in eliminating the inflammatory lesion but that re-osseointegration to the once-contaminated implant surface has been difficult or impossible to achieve. PURPOSE: The aim of this study was to examine the use of carbon dioxide (CO2) laser in combination with hydrogen peroxide in the treatment of experimentally induced periimplantitis lesions. MATERIALS AND METHODS: Three dental implants (ITI Dental Implant System, Straumann AG, Waldenburg, Switzerland) were placed in each side of the edentulous mandible of four beagle dogs. Implants with a turned surface and implants with a sand-blasted large-grit acid-etched (SLA) surface (SLA, Straumann AG, Waldenburg, Switzerland) were used. Experimental periimplantitis was induced during 3 months. Five weeks later each animal received tablets of amoxicillin and metronidazole for a period of 17 days. Three days after the start of the antibiotic treatment, full-thickness flaps were elevated, and the granulation tissue in the bone craters was removed. In the two anterior implant sites in both sides of the mandible, a combination of CO2 laser therapy and application of a water solution of hydrogen peroxide was used. The implant in the posterior site of each quadrant was cleaned with cotton pellets soaked in saline. Biopsy specimens were obtained 6 months later. RESULTS: The amount of re-osseointegration was 21% and 82% at laser-treated turned-surface implants and SLA implants, respectively, and 22% and 84% at saline-treated turned-surface implants and SLA implants, respectively. CONCLUSIONS: The present study demonstrated the following: (1) a combination of systemic antibiotics and local curettage and debridement resulted in the resolution of experimentally induced periimplantitis lesions; (2) at implants with a turned surface, a small amount of re-osseointegration was observed at the base of the bone defects whereas a considerable amount of re-osseointegration occurred at implants with an SLA surface; and (3) the use of CO2 laser and hydrogen peroxide during surgical therapy had no apparent effect on bone formation and re-osseointegration.

Social network, social support and the rate of decline of CD4 lymphocytes in asymptomatic HIV-positive homosexual men.

AIMS: To test a stress-disease hypothesis by investigating the influence of social network and social support factors on the course over time of the CD4 lymphocytes in an HIV-positive population of gay men. METHODS: The study is a prospective cohort study of a representative population of HIV-positive gay men, undertaken at the Department of Infectious Diseases, Malmö University Hospital. This is the only clinic providing care for HIV-positive individuals in the city of Malmö in southern Sweden (population 248,000). A total of 115 HIV-positive homosexual men, who had not received an AIDS diagnosis, were invited to take part in the study. Seventy-five men (65%) accepted to be interviewed and 64 men (56%) fulfilled the inclusion criteria for the statistical analysis. RESULTS: In a multivariate analysis adjustments were made for age, level of the first CD4 count and time since first contact with the clinic. Men with high family contact frequency had a longer half-life (20.3 years) of the CD4 lymphocyte count than men with a low family contact frequency (7.4 years) (p = 0.03). Men with high social participation also had a longer half-life of CD4 lymphocyte count (14.7 years), compared with men with low social participation (6.3 years, p = 0.10). CONCLUSIONS: The findings of this study imply the importance of social support and social network factors as modifiers of the rate of decline of the CD4 lymphocyte level, which is an important prognostic marker of survival in HIV-positive homosexual men.

A systematic review of the incidence of biological and technical complications in implant dentistry reported in prospective longitudinal studies of at least 5 years.

OBJECTIVE: To systematically review the incidence of biological and technical complications in implant therapy reported in prospective longitudinal studies of at least 5 years. METHODS: A MEDLINE search was conducted for prospective longitudinal studies with follow-up periods of at least 5 years. Screening and data abstraction were performed independently by multiple reviewers. The types of complications assessed were as follows: implant loss, sensory disturbance, soft tissue complications, peri-implantitis, bone loss >or=2.5 mm, implant fracture and technical complications related to implant components and suprastructures. RESULTS: The search provided 1310 titles and abstracts, out of which 159 were selected for full-text analysis. Finally, 51 studies were included. Meta analysis of these studies indicated that implant loss prior to functional loading is to be expected to occur in about 2.5% of all implants placed in implant therapy including more than one implant and when routine procedures are used. Implant loss during function occurs in about 2-3% of implants supporting fixed reconstructions, while in overdenture therapy >5% of the implants can be expected to be lost during a 5-year period. Few studies (41% of those included) reported data on the incidence of persisting sensory disturbance >1 year following implant surgery. Most of the studies that provided such data reported on the absence or a low incidence (1-2%) of this complication beyond this interval. A higher incidence of soft tissue complications was reported for patients treated with implants supporting overdentures. There is limited information regarding the occurrence of peri-implantitis and implants exhibiting bone loss >or=2.5 mm. Implant fracture is a rare complication and occurs in <1% of all implants during a 5-year period. The incidence of technical complications related to implant components and suprastructures was higher in overdentures than in fixed reconstructions. CONCLUSION: Implant loss was most frequently described (reported in about 100% of studies), while biological complications were considered in only 40-60% and technical complications in only 60-80% of the studies. This observation indicates that data on the incidence of biological and technical complications may be underestimated and should be interpreted with caution.