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Biomedical subjects

A Heimdahl

Publications and source records attributed to A Heimdahl.

At least 19 recordsLinked to original sources
PubMed2005

Development and characterization of an animal model of dental sinusitis.

CONCLUSION: The results of this study confirm that the present rabbit model of dental maxillary sinusitis (dMxS) is reproducible and simulates human dental sinusitis with respect to initiation, progression and inflammation. It is applicable to further studies of sinusitis of odontogenic origin. OBJECTIVES: To induce acute dMxS in rabbits by using their own oral microflora to create a periapical infection and to follow morphological, radiographic, bacteriological and histological changes to the sinus mucosa. MATERIAL AND METHODS: The experimental animals comprised 26 New Zealand White rabbits. Maxillary premolar root canals were identified bilaterally and the continuously growing germs of the roots were severed by diathermy. The animals were randomized into 2 groups: in Group 1 (n=20) the teeth were left open for the entire study period; in Group 2 (n=6) the root canals were sealed 1 week after the initial intervention. The animals in Group 1 were sacrificed at intervals ranging from 2 h to 9 months after intervention. All animals in Group 2 were sacrificed 6 months after intervention. After macroscopic and radiographic examination, post-mortem inspection of the paranasal sinus cavity and maxillary complex and microbiological sampling, the entire nasal sinus complex with the hard palate in situ was resected and processed for serial coronal sectioning. RESULTS: In Group 1, after 3 months, the radiographic changes ranged from widening of the periodontal space to bone reaction. At sacrifice, changes in the sinus mucosa ranged from signs of mucosal inflammation to purulent dMxS. Microbial growth, predominantly Gram-negative aerobes, increased over time. In Group 2, the findings were generally more pronounced. Anaerobic microorganisms were predominant. In both groups the findings were consistent with dMxS.

Animals↗
PubMed2004

Reduced susceptibility to penicillin of viridans group streptococci in the oral cavity of patients with haematological disease.

The occurrence of oral penicillin-resistant viridans group streptococci (VGS) was studied in 50 patients with either newly diagnosed acute leukaemia or autologous peripheral stem cell transplants. One patient was excluded because of Staphylococcus aureus growth in the stem cell harvest. VGS were isolated from the oral cavity of 48 of the remaining 49 patients. Of these 48 patients, 12 (25%) yielded VGS resistant (MIC > 2 mg/L) to penicillin. These 12 patients had a higher frequency of septicaemia (p 0.04) and more days of treatment with trimethoprim-sulphamethoxazole (p 0.04) than patients who harboured susceptible or intermediately resistant VGS (MIC 2 mg/L). There were no other statistically significant differences between the two groups. It is important to be aware of the high level of penicillin resistance in oral VGS in patients with haematological disease, and this parameter should be considered when selecting antibiotic therapy for cases of septicaemia caused by VGS in immunocompromised patients.

Adult↗
PubMed2001

Brånemark System and ITI Dental Implant System for treatment of mandibular edentulism. A comparative randomized study: 3-year follow-up.

In a randomized prospective study, two implant systems were compared in forty consecutive patients treated for mandibular edentulism. The patients were randomly allotted for treatment by the Brånemark two-stage (submerged) system (BRS), or the ITI(R) one-stage (non-submerged) system. In all, 102 Brånemark selftapping implants and 106 ITI hollow screw implants were installed and all patients were treated with full bridges. Biological and prosthodontic parameters, complications, success rates, clinical efficacy, patient satisfaction and resource requirements were evaluated. No differences were found in plaque accumulation, bleeding or complications during the follow-up period. The BRS group showed deeper periimplant sulcus, less attached mucosa, larger bridge-mucosa distance and higher Periotest values. Prosthetic complications were not related to the configuration of the implant systems. After 3 years, the cumulative success rates were 97.9% and 96.8% for the Brånemark and ITI systems, respectively (difference not statistically significant). One implant in the BRS group had failed to osseointegrate at the time of abutment connection, and another was lost after 2 years due to progressive breakdown of bone. In the ITI group, three implants showed progressive bone loss after 1-3 years associated with periimplant infection. All 40 bridges were intact and remained stable throughout the study. There was general patient satisfaction, but about half the Brånemark patients reported difficulty in coping with the surgical procedures. Treatment time was similar for the two systems. It is concluded that both systems meet the current requirements for dental implant systems in the treatment of mandibular edentulism.

Adaptation, Psychological↗
PubMed2000

Bone grafting to the maxillary sinus from the lateral side of the mandible.

Patients who were unable to have an implant of the maxilla without a bone graft were operated on by a modified sinus lift method, under local anaesthesia. Cortical bone grafts, harvested from the lateral side of the mandible, were forced horizontally into a slot, made in the lateral sinus wall after a mucosal sinus lift. The immediate stabilization of the graft permitted the dense packing of the space below the horizontal graft with bone chips, which probably contributed to the fast healing of the bone. We saw eight patients (10 sites) for long-term follow-up. Two or three Brånemark standard implants were inserted into the grafted area 3 months postoperatively. The abutments were connected 5 to 6 months after implantation. We have now adopted this modified method as the standard for bone grafting to the maxillary sinus in both of our maxillofacial centres.

Adult↗
PubMed2000

Direct oral microscopy and its value in diagnosing mucosal lesions: a pilot study.

OBJECTIVE: Clinical examination of the oral mucosa often leads to an uncertain diagnosis, and a supplementary biopsy with a histopathologic examination of the lesion is necessary to establish a definite diagnosis. However, the site for the biopsy is a subjective choice that sometimes raises doubts about its representativeness. So far, no simple and reliable method is available for selecting the most appropriate area for biopsy. STUDY DESIGN: In a prospective study, we performed direct oral microscopy (oral application of the colposcopy technique used in gynecology) in 35 patients with various clinical diagnoses, such as leukoplakia, oral lichenoid lesions, or suspected malignancy. First, the oral mucosa was examined with direct microscopy, and the most representative site, according to colposcopic criteria, was selected. Then, the mucosa was clinically inspected by an independent examiner. The best site for biopsy according to clinical criteria was noted, and any difference in biopsy sites was recorded. Biopsy specimens were taken from 2 of these sites. RESULTS: Twenty-nine patients (83%) showed changes in the vascular picture on microscopy, according to the colposcopy criteria. In 14 patients (40%), the biopsy sites identified by direct oral microscopy showed more advanced histologic signs than those selected by routine clinical examination (0.01 < P </=.05). Four patients (11%) had more advanced histologic signs in the biopsy samples, as identified during routine clinical examination. In 17 patients (49%), we found no differences between the biopsy specimens. CONCLUSION: Direct oral microscopy of mucosal lesions seems to offer advantages in selecting more representative sites for biopsy than routine clinical examination alone.

Adult↗
PubMed1999

Prevention and management of oral infections in cancer patients.

The successful prevention and management of oral infections and infections from the oral cavity in cancer patients are based on identification of risk patients, selection of patients for prophylactic measures, diagnosis of infection and implementation of directed or empiric antimicrobial therapy. Identification of patients at risk for infection is based on each patient's type of oral microbial colonization and the presence of latent viral infections. Systemic and local resistance to infection will be decisive, and in many patients the risk can be estimated from the expected myelosuppressive effect of anticancer treatment. Diagnosis of infection is often based on clinical findings together with the results of microbiological investigations. Biopsies could be useful, but can seldom be obtained. Blood samples are mandatory for isolation of microorganisms involved in systemic infections in myelosuppressed patients. Prevention of infection requires both local and systemic measures. Elimination of the risk of a breach in the first line of defence is urgent, and the maintenance of mucosal integrity is important. Monitoring microbial colonization is common, as is the institution of antiviral prophylaxis in patients with increased anti-HSV IgG (ELISA > 10,000). Antifungal prophylaxis, to avoid colonization and superinfection, should be instituted in patients with low neutrophil counts. Gastrointestinal prophylaxis with quinolones is also commonly used in these patient groups. Treatment of oral infections in cancer patients should include systemic antimicrobial agents in most cases. Special attention should be directed to oral infections in neutropenic (< 0.5 x 10(9)/1) patients in whom oral microorganisms are the leading cause of bacteraemia. Invasive fungal infections of the oral cavity can be associated with systemic fungal infection and are indications for the use of liposomal amphotericin B.

Female↗
PubMed1999

Evaluation of single-tooth restorations on ITI dental implants. A prospective study of 29 patients.

From January 1992 to March 1997, a total of 30 ITI hollow cylinder implants were installed to replace lost single maxillary incisor teeth. Conical abutments with cemented all-ceramic crowns were used in 10 cases and the Octa-abutment with screw-retained metallo-ceramic crowns in 19 cases. One implant failed due to postoperative infection, and was extracted a month after installation. After a mean observation time of 3.4 years, the cumulative success rate is 96.7%. Only minor bone loss has occurred around the implants, and there have been no other complications to date. The implant system fulfills the requirements for good function and esthetics.

Adult↗
PubMed1998

Comparison of E test and agar dilution methods for determining antibiotic susceptibilities of anaerobic bacteria and viridans streptococci isolated from blood.

The antimicrobial susceptibilities of 311 strains of anaerobic bacteria and 140 strains of aerobic bacteria, isolated from blood after dental extraction, were determined by the E test and compared with the results obtained by the agar dilution method on PDM-ASM 2 agar. E test MICs agreed within +/-1 dilution step to the agar dilution MICs in 93%, 52%, 90%, 94% of the tested anaerobes for penicillin V, cefaclor, clindamycin and erythromycin, respectively. For aerobic bacteria the agreement was > or = 90% for the antibiotics tested. The in vitro activities of penicillin V, clindamycin and erythromycin were higher than the activity of cefaclor against the majority of bacteria tested.

Journal Article↗
PubMed1998

Virulence factors of Staphylococcus aureus in the pathogenesis of endocarditis. A comparative study of clinical isolates.

It is now generally accepted that adherence of microorganisms to various components of cardiac valve surfaces or vegetation lodging on the heart valves is an important early event in the pathogenesis of infective endocarditis. 120 clinical isolates of S. aureus obtained from patients with endocarditis and wound infections and from nasopharyngeal carriers were quantitatively analysed in vitro for their ability to bind to fibronectin and to produce protein A and alpha-toxin. Both cell-bound and extracellular protein A were measured and alpha-toxin was determined as antigen and as haemolytic activity. The highest fibronectin binding ability was found in carrier strains while no significant differences between strains were observed regarding the production of protein A. Strains isolated from patients with endocarditis produced significantly lower amounts of alpha-toxin than did strains from the other two groups. An inverse relationship between the production of protein A and of alpha-toxin was noticed in the material. Animal passage of five strains in an experimental endocarditis model showed a good reproducibility of the test systems and one strain was upregulated in its fibronectin binding ability and in alpha-toxin production. These in vitro results indicate that the fibronectin binding ability is not the decisive adherence factor and question the role of alpha-toxin as a virulence factor in endocarditis.

Animals↗
PubMed1998

Dental implant installation without antibiotic prophylaxis.

The objective of this study was to retrospectively compare the outcomes of dental implant treatment with and without antibiotic prophylaxis. Two groups of patients with edentulous or partially edentulous maxillas or mandibles (or both) were treated with dental implants. One group, consisting of 147 patients (790 implants), was given prophylaxis with oral phenoxymethylpenicillin; 1 g of antibiotic was administered 1 hour preoperatively, and 1 g was administered every 8 hours for 10 days postoperatively. The other group, consisting of 132 patients (664 implants) was not given any antibiotics preoperatively or postoperatively. There were no significant differences with respect to early and late postoperative infections or with respect to implant survival between the two groups. It appears that antibiotic prophylaxis for routine dental implant surgery offers no advantage for the patient.

Adolescent↗
PubMed1996

Effects of prophylactic administration of cefaclor on transient bacteremia after dental extraction.

This study was undertaken to investigate the effects of prophylactic administration of cefaclor on bacteremia after dental extraction. Thirty-nine patients were randomly assigned to receive either 1 g cefaclor (19 patients) or placebo (20 patients) 1 h prior to dental extraction. Blood samples for microbiological investigation were collected before, during, and 10 min after surgery, and were processed by lysis filtration under anaerobic conditions. The incidence of bacteremia with viridans streptococci was 79% in the cefaclor group and 50% in the placebo group during extraction. No difference in the incidence or magnitude of bacteremia was observed when the two patient groups were compared.

Adult↗
PubMed1996

Streptococcus mutans major adhesion surface protein, P1 (I/II), does not contribute to attachment to valvular vegetations or to the development of endocarditis in a rat model.

Streptococcus mutans P1 antigen functions as an adhesion factor for binding to salivary pellicle on tooth surfaces. It induces increased antibody titres in patients with Strep. mutans endocarditis. A mutant of Strep. mutans deficient in the function of the gene (spa P) encoding the surface antigen P1, and its isogenic parental strain, were used in a rat endocarditis experiment. Absence of P1 did not decrease adhesion to vegetations determined l h after intravenous infection. The number of bacteria recovered from valvular vegetations after 48 h from animals with manifest endocarditis did not differ between the strains. Consequently, the Pl antigen appears to be unimportant both for adhesion and virulence in endocarditis caused by Strep. mutans.

Animals↗
PubMed1996

Collagen binding of Staphylococcus aureus is a virulence factor in experimental endocarditis.

The role of Staphylococcus aureus collagen binding in the development of experimental endocarditis was studied. Two isogenic strains of S. aureus, 1 carrying an insertional inactivation of the gene encoding collagen-binding protein, were compared in a rat model of catheter-induced infective endocarditis (i.e.). Separate groups of rats with traumatized aortic valves were intravenously challenged with 1 of the strains. In rats sacrificed 24 h after inoculation, the collagen-binding strain significantly outnumbered the mutant strain (P < .001); however, 1 h after challenge, there was no difference in numbers of the 2 strains. The results were substantiated, using a 1:1 mixture of the parent strain and the mutant as an inoculate. Our findings suggest that collagen binding of S. aureus is important in the sustenance of experimental IE and plays a limited role during the initial attachment of the microorganism to traumatized aortic valves.

Animals↗
PubMed1996

Elimination of bacteraemia after dental extraction: comparison of erythromycin and clindamycin for prophylaxis of infective endocarditis.

Erythromycin and clindamycin are currently recommended for antibiotic prophylaxis of infective endocarditis in predisposed patients allergic to penicillin undergoing oral invasive procedures. Thirty-eight healthy patients were randomized to receive either erythromycin (1 g) or clindamycin (0.6 g) orally 1.5 h prior to dental extraction. Blood samples for microbiological investigation were collected before, during and 10 min after surgery and were processed by lysis filtration under anaerobic conditions. The incidence of bacteraemia with viridans streptococci was 79% in the erythromycin group and 74% in the clindamycin group. No statistically significant difference was noted in incidence or magnitude of bacteraemia with viridans streptococci or anaerobic bacteria between the two groups, at any sampling time. Ninety-six aerobic and 133 anaerobic strains recovered from the blood samples were tested for their susceptibility to erythromycin and clindamycin as well as to penicillin V and ampicillin. The antimicrobials were found to be highly active against the majority of bacteria except for some enterococci, staphylococci and veillonella. Protection from endocarditis by prophylaxis with erythromycin or clindamycin must be due to elimination of bacteria at a later stage in the development of the disease, rather than by elimination of bacteria from blood during the short period of postoperative bacteraemia.

Adult↗
PubMed1996

Lack of the extracellular 19-kilodalton fibrinogen-binding protein from Staphylococcus aureus decreases virulence in experimental wound infection.

A mutant deficient for the 19-kDa extracellular fibrinogen-binding protein (Fib) from Staphylococcus aureus has been constructed. The gene was inactivated by allele replacement. A 2.0-kb fragment from transposon Tn4001 carrying the gene for gentamicin resistance was inserted into the gene encoding Fib (fib). The genotype was verified by PCR analysis, and the loss of Fib was demonstrated by Western blotting (immunoblotting). The mutation has not altered the ability of the strain to bind to fibrinogen or fibronectin compared with that of the isogenic parental strain, FDA486. The mutant, designated K4.3, was compared with strain FDA486 in a wound infection model in rats. Sixty-eight percent of the rats challenged with parental strain FDA486 developed severe clinical signs of wound infection, whereas only 29% of the animals challenged with isogenic mutant K4.3 showed severe symptoms (P < 0.01). The weight loss of animals infected with the wild type was also significantly different from that of animals infected with the mutant strain. The result demonstrates that the extracellular 19-kDa fibrinogen-binding protein from S. aureus contributes to the virulence in wound infection and delays the healing process.

Alleles↗
PubMed1996

Reconsideration of the role of fibronectin binding in endocarditis caused by Staphylococcus aureus.

The adherence characteristics in vivo and virulence of two isogenic strains of Staphylococcus aureus differing in fibronectin binding were compared in a rat model of catheter-induced infective endocarditis. No differences were found between the two strains. The results strongly point to the multifactorial nature of bacterial adherence to damaged heart valves and suggest that other binding functions can compensate for the lack of fibronectin binding in S. aureus.

Animals↗