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Biomedical subjects

I Ericsson

Publications and source records attributed to I Ericsson.

87 records · Page 5Linked to original sources
PubMed1977

Lack of effect of trauma from occlusion on the recurrence of experimental periodontitis.

The experiments were performed in 15 dogs fed a diet which allowed dental plaque accumulation. A phase of experimental periodontal breakdown was initiated on day 0. After 210 days five dogs were sacrificed. In the remaining 10 dogs the periodontal pockets around the fourth lower premolars (4P and P4) were eliminated. During surgery a notch was prepared in the root at the level of the marginal termination of the alveolar bone in order to facilitate measurements in histological sections. From day 210 to day 450 the teeth of the animals were brushed twice daily. After 60 days of healing, i.e. on day 270, five of the dogs were sacrificed. Trauma from occlusion of the jiggling type was on day 270 produced in the P4 region of the remaining dogs by the installation of a cap splint and a bar device. The final five dogs were sacrificed on day 450. Following sacrifice, tissue sections comprising 3P, 4P, 1M and P3, P4, M1 were produced and subjected to microscopic analysis. The experiments revealed that, in the dog, forces produced by occlusal trauma are unable to induce a phase of progressive destruction of the periodontal tissues in tooth regions where the supporting tissues are markedly reduced but non-inflammatory.

Alveolar Process↗
PubMed1977

Pyrolysis gas chromatography -- a potential technique for characterization of complex organic material.

A pyrolysis gas chromatography (PGC) technique is described and various pyrolysers discussed. Results from analyses of synthetic polymers and organic salts are given. The influence of temperature rise time, pyrolysis temperature, pyrolysis time and sample size is considered. Pyrolysis studies on microorganisms are described various ways of improving the technique are considered.

Chromatography, Gas↗
PubMed1977

Pyrolysis gas chromatography of microorganisms. Influence of various pyrolysis parameters on the yield of volatile organic products.

Bacteroides fragilis was analysed by pyrolysis gas chromatography (PGC). The influence of temperature rise time, pyrolysis temperature and pyrolysis time on the yield of volatile organic pyrolysis products was studied. The use of short pyrolysis time (8 msec) and a high pyrolysis end temperature (1300 degrees C) was found to provide a high yield. In consecutive analyses of the test organism, under the pyrolysis conditions indicated, the standard deviation of the total yield of volatile organic products was +/- 7%. The pyrolysis technique described suggests that few secondary reactions of the pyrolysis fragments occur.

Bacteroides fragilis↗
PubMed1976

The influence of trauma from occlusion on reduced but healthy periodontal tissues in dogs.

The experiments were performed in five dogs fed a soft diet which allowed dental plaque accumulation. Experimental periodontal breakdown was introduced on Day 0. After 180 days trauma from occlusion was produced in 4P and P4 i.e. the mandibular fourth premolars, in the manner described by Svanberg & Lindhe (1973). On day 280 the periodontal pockets around 4P and P4 were eliminated. A notch was prepared in the root at the level of the bottom of the surgically eradicated pocket. In addition, the occlusal trauma in the 4P region was deleted. From Day 280 to Day 370 the teeth of the animals were brushed twice a day. The animals were then sacrificed, radiographs of the premolar regions were taken, and tissue sections comprising 3P4P1M (and P3P4M1) were produced and subjected to microscopic analysis. The results indicate that jiggling type occlusal trauma and tooth hypermobility are not factors which detrimentally affect healing following periodontal surgery.

Alveolar Process↗
PubMed1975

Experimental periodontal breakdown in the dog.

This paper describes a method for inducing rapidly progressing and reproducible periodontal lesions around selected teeth in dogs. The experiments were performed on 10 beagles which were fed a diet favoring gross formation of plaque. Approximately 1 mm of the marginal alveolar bone aroumd 4P and P4 was removed and a notch prepared in the root. A ligature of cotton floss was placed around 4P and P4 at the cemento-enamel junction. Radiographs and sections prepared 230 d later revealed that a progressive breakdown of the periodontal tissues had occurred. The average bone loss was 2.4 mm and the distance between the apical cells of the pocket epithelium and the notch was 854 mum.

Animals↗
PubMedDate not supplied

In vitro and in vivo experimental studies on single crystal sapphire dental implants.

Successful attachment of the oral tissues to an endosseous dental implant relies in part on its chemical stability, nontoxic properties and maintenance of normal cell functions in the surrounding tissues. The aim of this study was therefore to investigate these 3 factors experimentally. The corrosion resistance of single crystal sapphire (alpha-Al2O3) implants was analysed with respect to the release of aluminium ions; no ions could be detected in the test solutions. The influence of single crystal sapphire on the behaviour of human epithelial cells and fibroblasts derived from biopsies of the oral mucosa, was studied. The cells were cultured in chemically defined or in low serum-containing media. Compared to the corresponding control cultures, no effects on cell morphology and growth characteristics were observed. Sapphire rods were inserted subcutaneously into rats and tissue responses were examined after 4, 8 and 12 weeks post-implantation. None or slight reactions were found in the tissues. The combined evaluation of these experimental approaches indicates that single crystal sapphire is a material well suited for biological implantation.

Aluminum Oxide↗
PubMedDate not supplied

The soft tissue barrier at implants and teeth.

In the present animal experiment, analyses and comparisons were made between the structure and composition of clinically healthy supraalveolar soft tissues adjacent to implants and teeth. 5 beagle dogs were used. The right mandibular premolar region was selected in each dog for placement of titanium implants, while the left mandibular premolar region served as control. Extractions of the mandibular premolars were preformed, healing allowed, following which titanium fixtures were installed in the edentolous premolar region. Abutment connection was carried out 3 months later. After another 2 months of healing, plaque control was initiated and maintained for 8 weeks. At the end of the plaque control period, clinical examinations were performed and biopsies harvested from the implant site and the contralateral premolar tooth region. Following fixation and decalcification, all tissue samples were embedded in EPON and examined by histometric and morphometric means. The result from the analyses demonstrated that the periimplant mucosa which formed at titanium implants following abutment connection had many features in common with gingival tissue at teeth. Thus, like the gingiva, the peri-implant mucosa established a cuff-like barrier which adhered to the surface of the titanium abutment. Further, both the gingiva and the peri-implant mucosa had a well-keratinized oral epithelium which was continuous with a junctional epithelium that faced the enamel or the titanium surface. In the periimplant mucosa, the collagen fibers appeared to commence at the marginal bone and were parallel with the abutment surface. All gingival and periimplant units examined were free from infiltrates of inflammatory cells. It was suggested that under the conditions of study, both types of soft tissues, gingiva and periimplant mucosa, have a proper potential to prevent subgingival plaque formation.

Animals↗
PubMedDate not supplied

Maxillary sinus augmentation using mandibular bone grafts and simultaneous installation of implants. A surgical technique.

This paper presents a specific technique for maxillary sinus augmentation and simultaneous placement of implants in partially edentulous patients. In such patients, there is from time to time insufficient interarch distance for any type of onlay grafting. Health, non-smoking patients without previous or present sinus pathology, where the radiological and clinical examination revealed insufficient height and/or width of the remaining alveolar process in the posterior maxillary region, were selected. They were operated on using a mandibular bone graft obtained from the symphyseal region between the mental foramina and placed in the maxillary sinus. The recipient site was prepared by cutting in a rectangular shape the lateral sinus wall into the sinus lining. The bone wall was then separated towards the lateral nasal wall by rotating the inferior portion of the cut sinus wall medially. In the space thus created, the bone graft was placed. Fixtures were installed at the same session. The method described has proved to be uncomplicated to perform under local anesthesia and no major disadvantages for the patient or pre- or postoperative complications have so far been observed.

Alveolar Bone Loss↗
PubMedDate not supplied

Formation and effects of leukotrienes and lipoxins in human bone marrow.

The present results demonstrate leukotriene and lipoxin synthesis in human bone marrow and link these findings to biological effects in the same tissue. However, the mechanisms behind the described effects on myeloid progenitor cell growth are presently unknown. It is conceivable that both leukotrienes and lipoxins may act through modulation of endogenous cytokine production. However, it should be noted, that these lipoxygenase products totally failed to induce colony growth in the absence of GM-CSF. Moreover, the role of lipoxins in the bone marrow needs to be further clarified, since LXA4 induced both synergistic (with GM-CSF) and antagonistic (with LTC4) effects on progenitor cell growth. A possible pathophysiological role for leukotrienes and lipoxins may be suggested in chronic myelogenous leukemia. Thus, the capacity of hematological cells from CML patients to synthesize LTC4 was significantly increased. In addition, we have recently reported that CML platelets possessed a markedly decreased ability to participate in transcellular synthesis of the potential inhibitors of myelopoiesis, LXA4 and 5(S),12(S)-diHETE (Stenke et al., 1991b). Moreover, the production of these compounds was totally abolished in platelets obtained from CML patients in blastic crisis. Further studies should aim at defining the mechanisms behind the regulatory actions of leukotrienes and lipoxins in normal and leukemic human myelopoiesis.

Bone Marrow↗