Biomedical subjects

L Sennerby

Publications and source records attributed to L Sennerby.

At least 91 records · Page 5Linked to original sources

PubMed1990

Trypsin-induced vascular permeability and leukocyte accumulation in hamster cheek pouch: the role of complement activation.

Trypsin-induced acute inflammation was studied in hamster cheek pouch using intravital microscopy, correlative histology, and electron microscopy. Vascular permeability changes were monitored with intravital fluoroscopy, after intravenous injection of FITC-dextran (Mw 150,000), by counting the number of FITC-dextran leakages around the vessels. The number of extravasated polymorphonuclear leukocytes (PMNLs) was calculated by a histological technique. A dose-dependent increase in the number of FITC-dextran leakages, as well as the number of accumulated PMNLs, was found when trypsin was locally deposited in concentrations of 0.25-2.5 microM (15 microliters during 5 min). Local deposition of autologous serum treated with trypsin at final concentrations of 0.25-2.5 microM caused an increase in vascular permeability as equally pronounced as that of pure trypsin, but only a moderate PMNL accumulation which was not dose dependent. Trypsin at a 25 microM concentration resulted in numerous microbleedings and cessation of flow. The electron microscopy demonstrated inflammatory events (PMNL adhesion, diapedesis, and interstitial infiltration) in all treatment groups but they were more pronounced after trypsin exposure. Trypsin did not cause disintegration, cellular lysis, or increased mast cell degranulation. The permeability changes induced by trypsin (2.5 microM) and trypsinated serum (2.5 microM) were significantly suppressed by the addition of the chelating agent potassium-EDTA to the reaction mixture, indicating a calcium- or magnesium-dependent mechanism. Pretreatment of the animals with cobra venom factor (CVF), by which the plasma C3 concentration was reduced to less than 10%, inhibited the vascular leakages almost completely. The trypsin-induced accumulation of PMNLs was significantly reduced by potassium-EDTA as well as by pretreatment with CVF (P less than 0.01). These findings indicate a central role of complement activation in trypsin-induced acute inflammation in the hamster cheek pouch.

Animals↗

PubMed1990

Separation of non-collagenous proteins of bone formed in titanium implants: experimental study in the rabbit tibia, using a bone harvest chamber.

The non-collagenous proteins of mature cortical rabbit bone and 3 wk old bone specimens formed in titanium implant bone harvest chambers, were separated by means of fine pressure liquid chromatography. It was found that a sufficient amount of bone could be obtained from five bone harvest chambers in five rabbits during a period of 15 wk. A different protein chromatographic pattern was found in bone grown in bone harvest chambers as compared to normal cortical bone from the same region. This indicates a difference in bone quality and shows that this implant design can be used for biochemical analysis of bone formed adjacent to a biomaterial.

Animals↗

PubMed1990

[Direct bone anchorage of oral implants: clinical and experimental considerations of the concept of osseointegration].

The term osseointegration is analyzed in relation to its theoretical and clinical definitions, and comparisons are made to other implant modalities. The term osseointegration has a clear clinical meaning, but there is doubt about its precise usage in an experimental setting. Clinically, an implant can be described as osseointegrated if there is no discernable movement when force is applied to the fixture. This is in contrast to implants surrounded by fibrous connective tissue, which move within soft tissue. Newly developed laboratory techniques may be used in the future to precisely characterize osseointegration in the laboratory.

Dental Implantation↗

PubMed1990

Clinical report on the success of 47 consecutively placed Core-Vent implants followed from 3 months to 4 years.

This report presents the clinical outcome of 47 consecutively placed Core-Vent implants inserted in 35 patients followed for 2 to 4 years by clinical and 3 to 48 months by radiographic examination. The implants were used in mandibles and maxillae to support single crowns, overdentures, and fixed prostheses splinted to natural teeth as recommended by the manufacturer. Of the 47 implants, 43 could be examined. A total of 11 implants was removed, nine because of progressive vertical bone loss and two because of fractures. The vertical bone loss was calculated for the 32 remaining implants. Twenty-eight implants demonstrated a bone loss of more than 2 mm and 16 showed a loss of more than one-third of the implant height. According to the criteria proposed by Schnitman and Shulman in 1979, the total success rate was 37.2%. When using the criteria suggested by Albrektsson et al in 1986, the total success rate was calculated to be 9.3%.

Adult↗

PubMed1990

Macroscopic, microscopic and radiologic assessment of the condylar part of the TMJ in elderly subjects. An autopsy study.

Thirty-seven temporomandibular joints were examined in an autopsy study. The sizes and forms of the condyles were found to be in good agreement with earlier presented results. Structural changes were found in 16 condyles (38%) in the macroscopic examination, while radiographically diagnosed erosions were found in 8 (21%). Twenty-two (59%) of the discs examined had either perforations, roughness or attenuations. Anterior disc position was found in 3 discs, and always in combination with a perforation of the disc.

Aged↗

PubMed1990

Microvascular effects of chondroitinase ABC and chymopapain. An in vivo experimental study on hamsters and rabbits.

Immediate and long-term microvascular effects of chondroitinase ABC, 200 unit/ml, were analyzed in ten hamsters. The immediate effects on the microcirculation were studied by vital microscopy following local injection in the cheek pouch. There were no detectable effects on the microvascular blood flow during the 60 minutes of observation for chondroitinase ABC or the control. A therapeutic concentration (2000 pKat/ml) of chymopapain stopped the microcirculation in the injected area immediately, with numerous microbleedings at the border zone. Long-term effects were studied after subcutaneous injections in the ears of six rabbits. Chondroitinase ABC and the control did not cause any macroscopic or microangiographic effects. However, light microscopy showed a moderate inflammatory reaction in the subcutaneous layer for both chondroitinase ABC and the control. Chymopapain induced severe effects on the cartilage and surrounding tissues. Microangiography revealed a vessel-free zone at the injection site. Since 200 units/ml of chondroitinase ABC is four to eight times higher than the concentration that might be used for chemonucleolysis, i.e., dissolution of intervertebral discs by local enzyme injection, the present investigation suggests a wide margin of safety regarding the potential effects on blood vessels in tissues surrounding the disc.

Animals↗

PubMed1989

Activation and migration of leukocytes and vascular leakage induced by serum-opsonized zymosan particles in hamster cheek pouch.

The effect of topically applied serum-opsonized zymosan (SOZ) and zymosan-activated serum (ZAS) was studied in the hamster cheek pouch. Our data suggest that early vascular leakage, evaluated by intravital fluorescence microscopy after injection of FITC-dextran, and accumulation of polymorphonuclear granulocytes (PMNGs), quantitated in fixed whole tissue specimens, induced by ZAS and SOZ were caused by complement activation, whereas the late leakages (greater than 20 min after SOZ application) was PMNG-dependent. Inhibition of prostaglandin and leukotriene synthesis by indomethacin, nordihydroguaiaretic acid (NDGA), and BW755C influence early and late vascular leakage as well as accumulation of PMNGs. These drugs also inhibited the activation of hamster PMNGs in vitro, as evaluated by chemiluminescence, in a dose-dependent manner. (-)-Terbutaline, an adrenergic beta agonist, decreased vascular leakage but had no effect on PMNG activation and accumulation.

Animals↗

PubMed1989

Generation of new bone around titanium implants using a membrane technique: an experimental study in rabbits.

Insufficient bone volume may be a significant problem in connection with dental implants. In this study, a technique based on the principle of guided tissue regeneration was tested for its ability to generate bone tissue around titanium implants. Implants were inserted in tibiae of rabbits. To create a secluded space for osteogenesis and to prevent soft-tissue ingrowth, a porous Teflon membrane was placed around exposed parts of the implant. Where a membrane had been used, the threads of the implant were completely covered with significant amounts of new bone. This study indicates that the membrane technique is a reconstructive surgical method that may be applicable to create new bone around exposed parts of titanium implants in a clinical setting.

Animals↗

PubMed1989

Soft-tissue response to clinically retrieved titanium cover screws reimplanted in the rat abdominal wall.

Clinically retrieved titanium implant cover screws (Brånemark implant system), rinsed in saline or subjected to ultrasonic cleaning and sterilization, as well as unused sterile screws were studied by scanning electron microscopy and implanted in the rat abdominal wall for 6 weeks. Irrespective of cleaning procedure, the heads of the clinically retrieved screws were covered by numerous contaminants not present on the unused screws. The reimplanted screws elicited a different tissue response than the unused screws. The tissue response to the contaminated screws was characterized by a significantly thicker fibrous capsule and by a significantly larger number of macrophages located close to the implant. Moreover, judging from their ultrastructure, studied with transmission electron microscopy, the macrophages appeared to be in a more active state when compared to those located adjacent to unused screws.

Animals↗

PubMed1988

Mandibular bone resorption in patients treated with tissue-integrated prostheses and in complete-denture wearers.

Mandibular bone resorption was studied in patients treated with tissue-integrated prostheses (TIP) and in complete-denture wearers by distance and area measurements on cephalometric radiographs. The area measurements were performed by means of a computer. Two TIP groups with short and long periods (mean = 2.4 and 23.9 years) of edentulousness and wearing complete dentures before fixture installation were followed up over 7-8 years. Mandibular bone resorption was remarkably small behind the distally positioned fixtures in comparison with the corresponding region in complete-denture wearers. Patients with complete dentures showed a continuous resorption of the mandibular alveolar ridge over 21 years, even though there were great individual variations. The bone loss was most pronounced anteriorly and during the first 2 years after extraction of the residual teeth. It is concluded that treatment with tissue-integrated prostheses seems to reduce bone resorption in the mandible, probably owing to favorable load conditions and adequate stimulation of the bone.

Bone Resorption↗

PubMed1987

Acute tissue reactions to potassium alginate with and without colour/flavour additives.

The acute tissue reactions to potassium alginate, locally applied to a microvascular bed, were studied with the use of the vital microscopic hamster cheek pouch model combined with correlative histology. This experimental model permitted us to study microvascular permeability, blood flow, vessel diameters and leucocyte adhesion to vessel walls intravitally, and leucocyte migration and mastcell degranulation histologically. Deionized water alone and potassium alginate with flavour and colour mixed in saline was found to cause severe microvascular alterations, while potassium alginate, without flavour and colour, but mixed in saline and applied to the microvasculature resulted in a minor inflammatory reaction.

Alginates↗

PubMed1985

Indomethacin, (-)-terbutaline (beta 2 agonist), and (+)-terbutaline in acute inflammation induced by repeated ischemia in hamster cheek pouch.

A mild and controlled acute inflammatory reaction in hamster cheek pouch was created without any exogenous, but rather by locally activated and liberated, mediators. A pressure of 60 mm Hg was applied to part of the everted cheek pouch eight times with a 10-min recovery period in between. The microvascular response was followed by intravital microscopy and the permeability changes were monitored with intravital fluoroscopy and intravenous FITC dextran (mol wt 150,000). The number of extravasated polymorphonuclear leukocytes (PMNLs) was calculated by a new, whole tissue, histological technique. In three experimental groups (-)-terbutaline (beta 2-receptor agonist) 0.05 mg/100 g body wt., (+)-terbutaline 0.05 mg/100 g body wt., and indomethacin 2 mg/100 g body wt. was given intravenously before pressure was applied. A fourth group, with no drug given, served as control. There was a rapid increase in the number of FITC dextran leakages and extravasated PMNLs in the control group. Indomethacin almost completely inhibited FITC dextran permeability and extravasation of PMNLs. The beta 2 agonist markedly diminished the number of FITC dextran leakages for 75 min. The number of extravasated PMNLs was also reduced. Treatment with (+)-terbutaline, which is supposed to have no beta 2-receptor effect, gave a slight reduction in number of FITC dextran leakages and almost a complete inhibition of PMNL extravasation. Thus we conclude that indomethacin is a very potent antiinflammatory agent even in the early phase of inflammation. (-)-Terbutaline diminished the inflammatory response, probably by preventing endothelial gap formation. (+)-Terbutaline prevented PMNL extravasation either by interaction with the PMNL itself or with the endothelium.

Animals↗

PubMedDate not supplied

Structure of the bone-titanium interface in retrieved clinical oral implants.

7 clinically stable, "osseointegrated", titanium implants, inserted in human jaws for 1-16 years, were retrieved for morphological analysis of the bone-titanium interface, using 3 different preparation techniques. The bone-titanium interface varied as judged from light microscopy of ground sections. The threads of the implants were well filled (79-95%) with dense lamellar bone as quantified with morphometry. A large fraction of the implant surface (56-85%) appeared to be in direct contact with the mineralized bone. In general, the non-bone areas consisted of pockets with osteocytes, bone marrow tissue and/or vessels. Sections were prepared for light microscopy and transmission electron microscopy using a fracture technique, where the implant was separated from the embedded tissue before sectioning, and an electropolishing technique, where the bulk part of the implant was electrochemically removed. In areas judged as direct mineralized bone-titanium contact in the light microscope, the interfacial structure varied at the ultrastructural level. In areas along the interface, unmineralized tissue was present either as a narrow 0.5-1 micron wide zone containing collagen fibril or as deeper pockets containing osteocytes or vessels. In areas with mineralized bone contact, an amorphous granular layer (100-400 nm wide) with no mineral was observed in the innermost interface bordering the mineralized bone, with an electron-dense lamina limitans-like line (approximately 50 nm thick). It is concluded that the bone-titanium interface of the 7 clinically retrieved titanium oral implants examined in the present study bone was heterogenous. In areas of a direct mineralized bone-titanium contact at the ultrastructural level, mineralized bone reached close to the implant surface, but was separated by an amorphous layer, being 100-400 nm thick.

Aged↗

PubMedDate not supplied

Influence of variations in implant diameters: a 3- to 5-year retrospective clinical report.

Sixty-seven patients ranging in age from 16 to 86 years were included in this 3- to 5-year retrospective report focusing on implant survival and marginal bone remodeling in relation to implant diameter. A total of 299 Brånemark implants (3.75-mm diameter: 141; 4.0-mm diameter: 61; 5.0-mm diameter: 97) were placed in 16 completely and 51 partially edentulous arches. Seven of the 141 implants in the 3.75-mm-diameter group failed (5%). The corresponding value for the 4.0-mm-wide implants was 2 of 61 (3%). The highest failure rate, 18% (17/97), was seen for the 5.0-mm-diameter implants. The least favorable cumulative survival rates were seen in mandibles after 5 years and involving 4.0-mm- and 5.0-mm-diameter implants (84.8% and 73.0%, respectively). The marginal bone loss was generally low over the 5-year period. When the data were evaluated by the Cox regression analysis, a relationship was found between implant failure and implant diameter (P < .05), with a higher failure rate for the 5.0-mm-diameter implant. However, no relationship could be seen between implant failure and jaw type, or bone quality and quantity (P > .05). Neither was any relationship seen between marginal bone loss and bone quality and quantity, implant diameter, or jaw type when tested by multiple linear regression analysis (P > .05). A learning curve, poor bone quality, and changed implant design were suggested as possible reasons for the less positive outcome seen for the 5.0-mm-diameter implant. The fact that this implant was often used as a rescue implant when the standard ones were not considered suitable or did not reach initial stability was another plausible explanation.

Adolescent↗

PubMedDate not supplied

Direct bone anchorage of oral implants: clinical and experimental considerations of the concept of osseointegration.

Alveolar Process↗

PubMedDate not supplied

Soft tissue and marginal bone conditions at osseointegrated implants that have exposed threads: a 5-year retrospective study.

The purpose of this retrospective clinical investigation was to study possible soft tissue complications and marginal bone resorption related to exposed threads of osseointegrated Brånemark oral implants during a 5-year period. Group 1 comprised 27 patients with 38 test implants that had not become completely covered with bone at implant placement. Thirty control implants in 25 of the patients were each next to a test implant and had no exposed threads initially. Group 2 comprised 51 patients with 107 test implants that had developed marginal bone loss beyond the second thread, as judged radiographically at the first annual checkup. Forty-eight control implants showed no or minor marginal bone resorption up to the first thread. Initial marginal defects and fenestrations at Brånemark implants (group 1) did not lead to mucosal problems or progressive marginal bone resorption during the first 5 years of function. Moreover, bone resorption, seen after the first year of loading at initially completely bone-covered implants, did not lead to any specific soft tissue problems, nor did it result in any further progressive bone resorption during a subsequent 4-year period. Based on the observed low incidence of soft tissue pathology at implants with exposed threads, it is suggested that bone augmentation techniques in the situations studied be used with restriction.

Adolescent↗

PubMedDate not supplied

A qualitative and quantitative method for evaluating implant success: a 5-year retrospective analysis of the Brånemark implant.

A proposed protocol and differentiated success criteria for long-term evaluation of oral implants are presented. The protocol and criteria were applied to a retrospective patient material treated during a 1-year period and followed for 5 years. The protocol comprised a two-stage analysis of the collected clinical data. First, a quantitative analysis of the outcome was made using a life table. Based on the information obtained during the follow-up, each implant was categorized into one of three groups: unaccounted for, failure, or survival. A qualitative analysis of the survival group was then performed by active testing against defined criteria. Depending on the modes of clinical and radiographic examinations and their results, surviving implants were either further assigned to one of three success grades or remained in the survival group. The data are presented in a four-field table at one level of success. Strict success criteria together with individual stability testing and radiographic examination of each consecutive implant should be used when a new implant system is evaluated or when a new application is explored. Radiography alone and more moderate success criteria may be used to document routine treatments, provided that an already well-documented implant system is studied.

Adult↗

PubMedDate not supplied

Histologic analysis of clinically retrieved titanium microimplants placed in conjunction with maxillary sinus floor augmentation.

In this study, a new approach involving placement and subsequent retrieval of titanium microimplants was employed for the histologic investigation of the implant-tissue interface in conjunction with maxillary sinus floor augmentation. Nine patients scheduled for sinus floor augmentation and simultaneous placement of Brånemark implants were included in the study. After a sinus graft procedure and placement of implants, an additional microimplant was placed into the graft through the lateral wall of the sinus. At abutment connection, the microimplants were retrieved using a 3- or 5-mm-wide trephine drill. Six specimens were retrieved after 6 to 14 months from sites augmented with particulate radiated mineralized cancellous allograft. Another six implants were retrieved after 6 to 12 months from maxillary sinuses augmented with particulate autogenous bone grafts. The histologic analysis showed distinct differences between the two types of grafts. The sites with autogenous bones grafts displayed a normal morphology of bone and bone marrow, including formation of bone on the surfaces of the grafted particles and remodeling of newly formed as well as grafted bone. The bone was more mature after 11 to 14 months than at 6 months. The allografted sites had a mixed morphologic appearance of newly formed bone and nonviable allograft particles (about 75% of the total bone area) in loose connective tissue. Significantly more bone was found at the autografted than at the allografted implants. The use of autogenous bone for augmentation of the maxillary sinus floor resulted in a greater amount of viable bone surrounding the implant; however, simultaneous placement of implants apparently resulted in a low proportion of bone-implant contact after 6 to 14 months irrespective of graft type.

Adult↗