Biomedical subjects

Stefan Lundgren

Publications and source records attributed to Stefan Lundgren.

28 records · Page 2Linked to original sources

PubMed2003

Spontaneous bone formation in the maxillary sinus after removal of a cyst: coincidence or consequence?

BACKGROUND: Maxillary sinus floor-augmentation techniques are frequently used to increase the bone volume in the posterior edentulous maxilla to enable placement and integration of titanium implants. PURPOSE: The purpose of this report is to document an unexpected healing pattern after maxillary sinus surgery and to discuss the implications for future bone-augmentation techniques. MATERIALS AND METHODS: In a patient referred for sinus augmentation, an intrasinus mucosal cyst was removed 3 months prior to the planned augmentation procedure. A replaceable bone window was prepared in the lateral aspect of the sinus wall. The cyst was removed, the ruptured mucosa was sutured, and the bone window was replaced, resulting in a secluded space in the sinus. RESULTS: After 3 months of healing, the space between the replaced bony window and the lifted sinus membrane was filled with newly formed bone. The surgical technique was repeated in a second patient and resulted in a similar bone reformation pattern. CONCLUSION: Surgical trauma and the creation of a secluded space between the bone surfaces and the sinus mucosa result in spontaneous bone formation in the maxillary sinus. The surgical approach described may be used to achieve bone reformation to enable placement of dental implants without the addition of any grafting material.

Adult↗

PubMed2003

Ramus or chin grafts for maxillary sinus inlay and local onlay augmentation: comparison of donor site morbidity and complications.

BACKGROUND: The placement of endosseous implants in edentulous areas is frequently limited by inadequate bone volume of the residual ridge. Local bone grafts from the mandible are a convenient source of autogenous bone for alveolar reconstruction prior to implant placement. PURPOSE: The aim of the present study was to document and compare the morbidity and the frequency of complications occurring at two intraoral donor sites: the mandibular symphysis and the mandibular ramus. MATERIAL AND METHODS: This study reviewed 53 consecutively treated patients: 29 with autogenous bone grafts from the mandibular symphysis and 24 with mandibular ramus bone grafts. Each patient received a questionnaire 18 months after surgery regarding problems that may have occurred during the postoperative period. RESULTS: In the patients in whom bone was harvested from the mandibular ramus, there were fewer postoperative symptoms immediately after the operation than with mandibular symphysis harvesting. Twenty-two of the 29 patients with symphysis grafts experienced decreased sensitivity in the skin innervated by the mental nerve 1 month after the operation. Five of the 24 patients with ramus grafts experienced decreased sensitivity in the vestibular mucosa corresponding to the innervation of the buccal nerve. Eighteen months after the surgery, 15 of the 29 patients in the symphysis group still had some decreased sensitivity and presented with permanent altered sensation. Only one of the patients grafted from the mandibular ramus presented with permanent altered sensation in the posterior vestibular area. No major complication occurred in the donor sites in any of the 53 patients. CONCLUSION: The results of this study favored the use of the ascending mandibular ramus as an intraoral donor site for bone grafting.

Adult↗

PubMed2003

Donor site morbidity in two different approaches to anterior iliac crest bone harvesting.

BACKGROUND: Bone grafting is a surgical technique for the reconstruction of the atrophic edentulous maxilla prior to treatment with endosseous implants. The anterior iliac crest is a commonly used donor site. PURPOSE: The aim of this study was to evaluate the donor site morbidity and complications when harvesting corticocancellous bone from the medial table of the anterior iliac crest and compare this with results when bone was harvested from the lateral and superior table of the anterior iliac crest. In addition, the outcome of the oral rehabilitation was evaluated by means of a quality-of-life questionnaire. MATERIAL AND METHODS: The study was composed of 70 consecutively treated patients with a mean age of 56 years. The patients were retrospectively evaluated with regard to postoperative donor site morbidity and complications at the donor site. RESULTS: For the donor site morbidity, 74% of the patients were free of pain within 3 weeks, whereas 26% of the patients had a prolonged period of pain lasting from a few weeks to several months. For 11% of the patients, there was still some pain or discomfort 2 years after the grafting surgery. For gait disturbance the figures were similar: 79% had no problems after 3 weeks. For the eight patients who still had some pain after 2 years, which was considered permanent, three also had gait disturbance. There was a total of three major complications (4%), one iliac wing fracture and two neurologic injuries. CONCLUSION: When harvesting a large amount of unicortical corticocancellous bone blocks from the the superolateral site of the iliac crest with a "peel off" technique, morbidity and complication rates do not differ significantly compared with those of the traditional anterior medial approach. Oral rehabilitation with maxillary reconstruction with bone grafts from the iliac crest and endosseous implants significantly improved oral function, facial appearance, and recreation/social activities and resulted in an overall improvement in quality of life in formerly edentulous patients.

Adult↗

PubMed2002

Linkage between the CYP2C8 and CYP2C9 genetic polymorphisms.

Cytochrome P450 (CYP) 2C8 and 2C9 are polymorphic enzymes. The CYP2C8*3 and CYP2C9*2 are the major variant alleles in Caucasian populations. The enzymes encoded by these variant alleles have impaired function for the metabolism of several drug substrates. In the present study 1468 subjects that were used as population-based controls in the Stockholm Heart Epidemiology Program (SHEEP) were genotyped by allelic discrimination using a 5'-nuclease assay for CYP2C8*1, 2C8*3, 2C9*1, 2C9*2, and 2C9*3 variant alleles in which the frequencies appeared to be 0.91, 0.095, 0.83, 0.11, and 0.066, respectively. Approximately, 96% of the subjects with CYP2C8*3 allele also carried a CYP2C9*2 and 85% of the subjects that had CYP2C9*2 variant also carried a CYP2C8*3. The number of subjects carrying both of the CYP2C8*1*3 and CYP2C9*1*2 was 4.5-fold higher than expected. This strong association may be of importance especially for the metabolism of common substrates of CYP2C8 and CYP2C9 like arachidonic acid that produces physiologically active metabolites.

Aged↗

PubMed2002

Effect of cyclophosphamide on gene expression of cytochromes p450 and beta-actin in the HL-60 cell line.

Many studies have demonstrated that cyclophosphamide (CPA) can affect hepatic cytochrome p450 (CYP) isoenzyme activity in animals. We have investigated the effect of CPA on gene expression of various CYP enzymes as well as beta-actin in the human acute promyelocytic leukemia cell line (HL-60S) and its multidrug-resistant (MDR) phenotype HL-60R. Cells were incubated at different concentrations of CPA ranging between 50 micro g/ml and 5 mg/ml. In determination of cytotoxicity and resistance factor (RF: IC(50) HL-60R/IC(50) HL-60S), concentrations of 100 and 500 micro g/ml CPA were selected to treat HL-60S and HL-60R up to 72 h. CYP gene expression in the cells prior to and after treatment with CPA was determined using semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and real-time PCR. Unexposed cell lines did not contain measurable levels of mRNA for CYP2B6, CYP3A4, CYP2C9 and CYP2C19 and no induction was observed after exposure. However, CYP1B1-specific mRNA, which is predominantly expressed in HL-60 cell line, was suppressed after exposure to CPA in a concentration-dependent manner. Beta-actin gene expression was also decreased. The HL-60 RF to CPA was calculated to 0.71, indicating that the multidrug-resistant (MDR) phenotype is not involved in the mechanism of resistance to CPA. No CYPs were induced by CPA in vitro, which probably indicates that the CYP inducibility in blood cells is poor. Our study suggests that suppression of beta-actin gene expression contributes or is involved in the CPA cytotoxicity.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2002

Effect of caffeine exposure during pregnancy on birth weight and gestational age.

Epidemiologic studies have been unable to conclusively evaluate whether caffeine intake during pregnancy is associated with reduced birth weight and/or fetal growth restriction. The authors conducted a prospective, population-based cohort study to investigate the effect of caffeine on birth weight, gestational age, and birth weight standardized for gestational age (birth weight ratio). Of 953 women recruited in early pregnancy in Uppsala County, Sweden, from 1996 to 1998, 873 women delivering liveborn singleton infants were included in the analysis. Caffeine exposures were ascertained from in-person interviews at 6-12 and 32-34 completed gestational weeks, and maternal plasma was analyzed for cotinine levels as an indicator of smoking. Analysis of variance was used to estimate the effect of caffeine on birth weight, gestational age at delivery, and birth weight ratio after accounting for the effects of other covariates, such as maternal sociodemographic characteristics, plasma cotinine, and pregnancy symptoms. There were no associations between caffeine consumption and birth weight, gestational age, and birth weight ratio, neither when caffeine exposure was averaged from conception to the 32nd to 34th gestational weeks, nor when caffeine exposure was stratified by trimesters of pregnancy. These results do not support an association between moderate caffeine consumption and reduced birth weight, gestational age, or fetal growth.

Adult↗

PubMed2002

The effect of the CYP1A2 *1F mutation on CYP1A2 inducibility in pregnant women.

AIMS: To investigate the influence of the CYP1A2*1F mutation on CYP1A2 activity in smoking and nonsmoking pregnant women. METHODS: Pregnant women (n = 904) who served as control subjects in a case-control study of early fetal loss were investigated. They were phenotyped for CYP1A2 using dietary caffeine and the urinary ratio AFMU + 1X + 1 U/1,7 U. An assay for CYP1A2*1F using 5'-nuclease assay (Taqman) was developed to genotype the population. RESULTS: The frequencies of *1 A and *1F alleles among Swedish women were 0.29 and 0.71, respectively. There was no statistically significant difference in CYP1A2 activity between the genotypes, although a trend towards enhanced activity was observed in *1F/*1F (log MRc 0.77) and *1F/*1 A (log MRc 0.82) genotypes compared with the *1 A/*1 A genotype (log MRc 0.71) (anovaP = 0.07). The mean difference between the *1 A homozygotes and the heterozygotes was 0.11 [95% confidence interval of the difference: (-0.21, -0.01)] and that between the *1 A and *1F homozygotes was 0.05 [95% confidence interval of the difference: (-0.13, 0.03)]. No significant effect (P = 0.22) of the *1F on CYP1A2 activity was observed in smokers, tested using an interaction term (smoking * genotype) in the anova model (*1F/*1F log MRc 0.79, *1F/*1 A log MRc 0.86, and *1 A/*1 A log MRc 0.73). In smokers, there was no difference in ratio between homozygotes for the *1 A and *1F alleles [mean difference -0.06; 95% confidence interval of the difference: -0.22, 0.11] or between *1 A/*1 A and *1 A/*1F genotypes [mean difference -0.13; 95% confidence interval of the difference: -0.29, 0.04]. CONCLUSIONS: The effect of the CYP1A2*1F mutation on CYP1A2 activity in smoking pregnant women could not be confirmed.

Adult↗

PubMed2002

A prospective 1-year clinical and radiographic study of implants placed after maxillary sinus floor augmentation with bovine hydroxyapatite and autogenous bone.

PURPOSE: The purposes of this study were 1) to evaluate the survival rate of implants placed in maxillary sinuses augmented with bovine hydroxyapatite and autogenous bone 6 months before implant surgery and 2) to estimate dimensional changes of the bone graft with time using a new radiographic method. PATIENTS AND METHODS: Thirty maxillary sinuses in 20 consecutive patients with severe resorption (mean, 3.8 mm of remaining alveolar bone) were augmented with a mixture of 80% bovine hydroxyapatite and 20% autogenous bone mixed with fibrin glue to enable the placement of screw-shaped dental implants. After 6 months of primary healing, 108 implants were placed and followed with clinical and radiographic examinations during the first year of loading. Measurements of changes in height, width, and length of the grafted material were made on tomographic Scanora (Soredex Orion Corporation Ltd, Helsinki, Finland) and panoramic radiographs taken 3 and 12 months after grafting and after 1 year of bridge loading. RESULTS: Ten implants in 6 patients were lost during the study (9 before loading and 1 after 1 year of functional loading), for a survival rate of 90.7%. All patients received fixed restorations, and the bridge survival rate was 100% after 1 year of loading. Small (<10%) but statistically significant dimensional changes in the grafted material were seen during the study period. CONCLUSIONS: Acceptable short-term results can be obtained with implants placed after the use of bovine hydroxyapatite and autogenous bone for maxillary sinus floor augmentation. These grafts show good resistance to resorption.

Aged↗

PubMedDate not supplied

A clinical and histologic evaluation of implant integration in the posterior maxilla after sinus floor augmentation with autogenous bone, bovine hydroxyapatite, or a 20:80 mixture.

PURPOSE: This study was designed to clinically and histologically evaluate the integration of titanium implants in different grafting materials used for maxillary sinus augmentation procedures. MATERIALS AND METHODS: A total of 21 patients and 36 maxillary sinuses were augmented with (1) autogenous particulated bone from the mandibular ramus, (2) bovine hydroxyapatite (BH) with membrane coverage, or (3) an 80/20 mixture of BH and autogenous bone. The grafts were allowed to heal for 6 to 9 months prior to placement of microimplants for histology and standard implants for prosthetic rehabilitation. After another 6 months of healing, when abutments were connected, the microimplants were retrieved for histologic and morphometric analyses. The outcome of the standard implants was clinically evaluated after 1 year of loading. RESULTS: The mean bone-implant contact was 34.6 +/- 9.5%, 54.3 +/- 33.1%, and 31.6 +/- 19.1% for autogenous bone, mixture of 20% autogenous bone/80% BH, and 100% BH, respectively. The corresponding values for the bone area parameter were 37.7 +/- 31.3%, 39.9 +/- 8%, and 41.7 +/- 26.6%. The BH area was found to be 12.3 +/- 8.5% and 11.8 +/- 3.6% for 20% autogenous bone/80% BH and 100% BH, respectively. There were no statistically significant differences for any parameter between any of the groups. After 1 year of loading, 6 of the 33 implants placed in autogenous bone grafts, 2 of the 35 implants placed in the BH/autogenous bone mixture, and 2 of 43 implants placed in BH were lost. There were no statistically significant differences between any of the groups. DISCUSSION: The histomorphometric analysis showed no differences between the 3 groups, indicating that autogenous bone graft can be substituted with bovine hydroxyapatite to 80% or 100% when used for maxillary sinus floor augmentation. The effect of adding autogenous bone remains unclear but may allow for a reduction of the healing time. CONCLUSION: The results from this clinical and histologic study indicate that similar short-term results can be expected when using autogenous bone, BH, or a mixture of them for maxillary sinus floor augmentation and delayed placement of dental implants.

Absorbable Implants↗

PubMedDate not supplied

A histomorphometric comparison of the bone graft-titanium interface between interpositional and onlay/inlay bone grafting techniques.

PURPOSE: To analyze the bone graft-implant interface of titanium microimplants (MIs) placed at the time of bone grafting or after a healing period of 6 months and retrieved after another 6 to 14 months of healing. Integration of MIs placed in interpositional bone grafts (IBGs) in conjunction with a Le Fort I osteotomy was compared with the integration of those placed in onlay/inlay bone grafts (OBGs). MATERIALS AND METHODS: The severely atrophied edentulous maxillae of 23 patients (14 women, 9 men) were restored with autogenous bone grafts (either IBG [n=8] or OBG [n=15]) and titanium implants. Six-month periods were allowed between grafting, implant placement, and abutment connection. The bone-implant interface was studied histologically with the use of unloaded titanium MIs. RESULTS: Sixty-eight MIs were either (1) placed simultaneously with grafting and retrieved after 6, 12, or 14 months or (2) placed after 6 months of healing and retrieved after another 6 to 8 months. Histomorphometry indicated equal degrees of osseointegration for the 2 intraoral reconstruction techniques when looking at bone-implant contact, bone area in threads, and newly formed bone (NFB) (Student t test for unpaired observations). There was a significant difference between simultaneous and delayed implant placement with respect to BIC and NFB (Student t test for paired observations). Three additional MIs placed in the nongrafted residual alveolar ridge and retrieved after 6 months showed significantly more bone in threads and NFB (Student t test for paired observations; P = .003 and P = .009, respectively) compared to MIs placed at graft placement (6 months' healing). DISCUSSION: Timing of implant placement appeared more important than healing time or surgical technique. The delayed approach resulted in better implant integration, probably because of the initial revascularization of the graft. CONCLUSIONS: Implant integration was similar in the IBG and OBG groups. Placement of MIs after an initial healing period of 6 months resulted in better integration than placement simultaneously with grafting.

Adult↗