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Biomedical subjects

Ulf Lekholm

Publications and source records attributed to Ulf Lekholm.

12 recordsLinked to original sources
PubMed2005

Prevalence of subjects with progressive bone loss at implants.

AIM: The aim of the present study was to assess the prevalence of subjects with progressive bone loss at implants with a function time of at least 5 years. MATERIAL AND METHODS: Radiographs of 1346 patients who had attended annual follow-up visits at the Brånemark Clinic, Public Dental Services, Gothenburg, Sweden were retrieved. Six hundred and sixty-two subjects fulfilled the inclusion criteria. Thus, they all had been provided with implant-supported (Brånemark System) Nobel BioCare, Gothenburg, Sweden) fixed partial or complete dentures or single-tooth replacements with a documented function time in radiographs of at least 5 years. Implants that demonstrated progressive bone loss to a level of > or =3 threads of an implant were detected. The number of subjects who exhibited one or more implants with progressive bone loss to the threshold level was recorded. RESULTS: Twenty-eight percent of 662 included subjects had one or more implants with progressive bone loss. A logistic regression analysis revealed that the individuals in this group carried a significantly larger number of implants than the subjects in whom no implants with progressive loss were detected (6 vs. 4.8). Furthermore, >30% of the subjects in the group with progressive bone loss had > or =3 identified implants and that about 33% of all such implants in this group exhibited extensive bone loss. Out of the total 3413 implants included in the study, 423 implants (12.4%) demonstrated progressive bone loss. CONCLUSION: It is suggested that the prevalence of progressive bone loss at implants assessed from subject-based data is higher than that evaluated from implant-based data.

Adult↗
PubMed2004

Histopathological observations of human periimplantitis lesions.

OBJECTIVE: The aim of the present study was to analyze some characteristics of advanced and progressive periimplantitis lesions in man. MATERIAL AND METHODS: Soft tissue biopsies were obtained from 12 implants in six patients. The implants had been in function between 4 and 21 years and were, with one exception, located in the maxilla. The radiographic examination performed prior to biopsy revealed that all sites exhibited advanced bone loss. Further, clinical signs of severe inflammation, such as suppuration, swelling and/or fistula formation were detected in the majority of sites and seven of the 12 implants were found to be mobile at biopsy. Each biopsy was following fixation embedded in epoxy resin and sections were prepared for histometric and morphometric analysis. RESULTS AND CONCLUSION: It was demonstrated (i). that all soft tissue units harbored large inflammatory cell infiltrates (ICT) that extended to a position apical of a pocket epithelium and (ii). that about 60% of the lesions were occupied by inflammatory cells, among which plasma cells dominated. Numerous amounts of PMN cells occurred not only in the pocket epithelium and adjacent connective tissue areas, but were also present in peri-vascular compartments in more central areas of the ICT.

Aged↗
PubMed2003

Peri-implant bone alterations in relation to inter-unit distances. A 3-year retrospective study.

The aim of the present retrospective study was to evaluate longitudinal alterations in radiographic bone topography at proximal sites of three-unit implant-supported fixed partial prostheses during the first 3 years after bridge installation, in relation to vertical and horizontal inter-unit distances. The subjects were partially dentate patients who had received implant-supported fixed partial prostheses during the year 1995 at the Brånemark Clinic, Göteborg, Sweden. For inclusion in the study, the patient had to have a three-unit bridge construction supported by three implants in the posterior area of the jaw. Twenty-eight patients having 35 screw-retained prostheses on Brånemark standard implants fulfilled the inclusion criteria. Radiographs obtained at bridge installation and at 1- and 3-year follow-ups were assessed for implant positions, contact point level, bone level at implants and adjacent tooth and mid-proximal bone crest level. The data were analysed with respect to two proximal units: tooth/implant units (n=35) and implant/implant units (n=70). Multiple regression analyses were used to evaluate the influence of various factors on the peri-implant and periodontal bone level changes during the 3 years of follow-up. At the tooth/implant units, the mean bone loss over the 3 years was 0.5 mm at the implant and 0.4 mm at the tooth. Multiple regression analysis failed to identify significant explanatory factors for the peri-implant/periodontal bone level changes at the tooth/implant units (R2=0.28). At the implant/implant units, the peri-implant bone loss was 0.6-0.7 mm and was significantly influenced by the vertical inter-implant distance (P<0.01), the difference in bone level at baseline between two neighbouring implants (P<0.001) and the bone level changes at the opposed implant surface (P<0.001) (R2=0.49). Furthermore, the magnitude of apical displacement of the inter-implant bone crest level during the 3 years of follow-up was negatively associated with the horizontal inter-implant distance (P<0.05). The results of the study demonstrated that both vertical and horizontal differences in implant positions might influence bone alterations in the inter-implant area during the first 3 years of loading, while the data failed to show corresponding relationships for the bone changes at the proximal area between the implant and the neighbouring tooth.

Aged↗
PubMed2003

Some soft tissue characteristics at implant abutments with different surface topography. A study in humans.

BACKGROUND: : If an implant with a rough surface is exposed to the oral cavity, it may accumulate greater amounts of plaque than a smooth surface, which may lead to severe problems with mucositis and peri-implantitis. The purpose of the present paper was to investigate the early inflammatory response to mucosa-penetrating abutments prepared with varying surface roughness. METHODS: : Nine patients had all five of their original abutments exchanged to test abutments for a 4-week period. The test abutments were prepared with five different roughnesses. The surface roughness was measured with an optical profilometer. At the end of the test period, clinical evaluation was performed; the health of the surrounding mucosa, the amount of accumulated plaque and marginal bleeding were registered. One biopsy was taken from each test abutment. Qualitative and quantitative histological evaluations were performed. RESULTS: : There was a statistically significant difference between patients regarding the amount of accumulated plaque on the abutment surfaces and inflammatory cells, but no difference between the surface modifications in relation to plaque accumulation or number of inflammatory cells. CONCLUSION: : No relation was found between inflammatory response and abutment surface roughness after an evaluation time of 4 weeks in a human test model.

Aluminum Oxide↗
PubMed2003

Measurements of buccal tissue volumes at single-implant restorations after local bone grafting in maxillas: a 3-year clinical prospective study case series.

PURPOSE: The purpose of this study was to measure changes in buccal and proximal tissue volumes after local bone grafting and single-implant treatment. MATERIALS AND METHODS: Ten patients were provided with buccal bone grafts 6 months prior to implant treatment in central upper incisor regions. Following a healing time of 6 months, abutments and single-implant crowns were installed and followed up for 2 years. Clinical photographs and impressions were taken prior to the surgical intervention as well as after crown placement and at first and second annual checkups. The photographs and study models were analyzed with regard to papilla regeneration and changes in buccal crest volume during the study period by means of a clinical papilla index and optical scanning of study models. RESULTS: All bone grafts healed without problems. A significant reduction of the buccal crest volume (-50%, p <.01) was observed in the grafted area before abutment connection. However, a significant increase of tissue volume (+100%, p <.05) was noticed at the subsequent crown placement, followed by a second but slow reduction of the volume during the following 2 years of function. The interdental papillae increased significantly (p <.05) in volume during the first year, almost completely filling up the embrasure areas after 2 years. CONCLUSIONS: It may be concluded that local bone grafting seems to be a valuable protocol to create sufficient bone volume for implant placement. However, significant resorption of the graft may be present, which reduces the impact of grafting on the esthetic outcome. Instead, placement of the abutment cylinder and the crown seems to play a more important role for reestablishing the tissue volume at the implant-supported single crowns.

Adult↗
PubMed2003

Microbiologic diagnostics at titanium implants.

BACKGROUND: The microbiota found at periimplant lesions have been shown to contain putative periodontal pathogens as well as opportunistic species such as Staphylococcus spp, enterics, and Candida spp. Therefore, a microbiologic diagnosis may be of value as guidance before treatment of such lesions. PURPOSE: The aim of this study was to evaluate the prevalence of some putative pathogens associated with long-term followed-up cases using two different microbiologic procedures. MATERIALS AND METHODS: Fifteen subjects contributed with plaque samples from teeth and implants; these were analyzed with respect to 18 putative periimplant pathogens using cultural methods and a deoxyribonucleic acid DNA-DNA hybridization technique. RESULTS: The number of individuals positive for the analyzed pathogens was similar in samples taken from teeth and implants when analyzed with the DNA-DNA hybridization technique. When comparing detection frequency by culture procedure and by "checkerboard" technique at implants, the number of individuals positive for these species was lower with the traditional culture technique than with the checkerboard analyses. Using a higher cutoff point (> or = 4) with the checkerboard technique, the number of positive individuals was generally lower than that found with the culture technique. When comparing the techniques on an implant site level, the prevalence obtained by culture was lower for all analyzed species. If the specific species were present in the samples analyzed by the checkerboard technique, they were present only in every second sample analyzed with the culture technique. The high specificity values showed that if the checkerboard technique did not detect any Porphyromonas gingivalis, Prevotella intermedia, Actinobacillus actinomycetemcomitans, or Fusobacterium nucleatum, the bacteria were also undetectable by the culture technique. The two methods therefore did not overlap but did supplement each other. CONCLUSIONS: Based on the current results it is recommended that the technique used when analyzing microbiota around titanium implants should be a combination of the two protocols mentioned as they seem to give the most comprehensive outcome when used together.

Adult↗
PubMed2002

Long-term follow-up of osseointegrated titanium implants using clinical, radiographic and microbiological parameters.

The aim of this study was to longitudinally follow up osseointegrated titanium implants in partially dentate patients by clinical, radiographic and microbiological parameters in order to evaluate possible changes in the peri-implant health over time. Fifteen individuals treated with titanium implants, ad modum Brånemark, and followed for ten years were included in the study. Before implant placement ten years previously, the individuals had been treated for advanced periodontal disease and thereafter been included in a maintenance care program. The survival rate of the implants after ten years was 94.7%. The bone loss was 1.7 mm when using the abutment-fixture junction as a reference point. Of the individuals, 50% were positive for plaque at the implants. Bleeding on sulcus probing was present at 61% of the implant surfaces. Ten years previously, the individuals had been carriers of putative periodontal pathogens, such as Porphyromonas gingivalis, Prevotella intermedia, Actinobacillus actinomycetemcomitans, Capnocytophaga spp. and Campylobacter rectus, and were also carriers of these species at the current examination. The results of the present study suggest that the presence of these putative periodontal pathogens at implants may not be associated with an impaired implant treatment. These species are most likely part of the normal resident microbiota of most individuals and may therefore be found at random at both stable and progressing peri-implant sites.

Adult↗
PubMed2002

Outcome of implant therapy in relation to experienced loss of periodontal bone support: a retrospective 5- year study.

PURPOSE: The aim of this retrospective study was to analyse bone level alterations over a 5-year period at implants in the maxillary posterior segments in patients with varying experience of periodontal bone loss in the natural dentition before implant placement. MATERIALS AND METHODS: 97 partially dentate patients with a total of 346 Brånemark oral implants in the maxillary posterior segments were included. By assessing the degree of radiographic marginal bone loss in the remaining natural dentition at time of the implant therapy, an age-related bone loss score (ArB-score) was calculated for description of the patient's experience of periodontal destruction. The two end quartiles of the distribution of the subjects with regard to the ArB-score were defined as Non-Perio subjects and Perio subjects, respectively. The primary outcome variables were implant losses (implant failures) and radiographic peri-implant bone loss over the 5-year observation period. RESULTS: A total of 18 implants were lost during the 5 years, resulting in an overall failure rate of 5.2%. The corresponding failure rate was 3.3% for the Non-Perio and 8.0% for the Perio patients. The peri-implant bone loss from the time of abutment connection to 5 years averaged 1.8 mm (SD 0.7). Of the patients, 34% showed a mean bone loss of > 2 mm and 39% of all implants had experienced a bone loss of 2 mm at the 5-year examination. The Non-Perio and Perio patients showed a mean bone loss of 1.7 mm (0.8) and 2.2 mm (0.8), respectively. Multiple regression analysis revealed a statistically significant relationship between the ArB-score and the peri-implant bone level change from abutment connection to 5 years (P < 0.05). In all, 64% of Perio patients had a mean peri-implant bone loss of > 2 mm from the time of abutment connection, compared to 24% for the Non-Perio patients (P < 0.01). The percentage of implants showing 2 mm of bone loss between abutment connection and 5 years was 62% and 44% in the Perio and Non-Perio groups, respectively (P = 0.055). CONCLUSION: The results indicate that longitudinal bone loss around implants is correlated to previous experience of loss of periodontal bone support and that periodontitis susceptible subjects may show an increased implant failure rate.

Adult↗
PubMedDate not supplied

Statistical outcome of random versus selected withdrawal of dental implants.

PURPOSE: When performing clinical trials, missing data from withdrawn patients should be evaluated differently, depending on the reason for the withdrawal of the patients. The question is, if a certain type of patient drops out, will that affect the result? Could a randomly selected sample of a study population be used for analyses instead of evaluating each and every patient? The purpose of this study was to answer these questions. MATERIALS AND METHODS: Detailed information on 1,738 implants in 487 patients was pooled together in a new database and used for statistical evaluations. Random or selected withdrawals were pulled from the database. Chi-squared tests were used for significance tests, and lifetables were used for survival analysis. RESULTS: There was a difference in the outcome depending on whether the withdrawals were randomly chosen or selected. Random withdrawals could represent, in this study, as much as 50% of the included patients without changing the statistical results. If selected withdrawals were based on which jaw was treated, the statistical outcome did change, but it did not change if withdrawals were based on gender or age. CONCLUSION: Evaluation of reasons for withdrawals and withdrawn patient characteristics are of utmost importance when evaluating clinical trials. A randomly selected sample of the entire population could, however, be expected to give the same statistical value as the entire group, if the original material were large enough. Therefore, the use of study samples may more easily enable clinicians to do follow-up investigations.

Age Factors↗
PubMedDate not supplied

Evaluation of patient and implant characteristics as potential prognostic factors for oral implant failures.

PURPOSE: The purpose of this study was to evaluate patient, implant, and treatment characteristics to identify possible prognostic factors for implant failure. MATERIALS AND METHODS: Out of a database with different dental implant treatment protocols, a research database of 1 randomly selected implant per patient was created. The database consisted of 487 implants. Of these, 80 were withdrawn, 36 failed, and 371 remained successful during a 5-year follow-up period. Potential risk factors were evaluated by chi-square tests and post hoc analyses. RESULTS: Significant or strongly significant differences were found regarding implant failures as a result of jawbone quality, jaw shape, implant length, treatment protocol, and combinations of jawbone-related characteristics. Responsible clinics and number of implants supporting the restoration were factors that could not be associated with implant failure. DISCUSSION: Implant failures in this study were more often seen when negative patient-related factors were present. Approximately 65% of the patients with a combination of the 2 most negative bone-related factors (jawbone quality 4 and jaw shape D or E) experienced implant failure. However, only 3% of the patients had this combination. Implant length, the only implant-related factor evaluated, was also significantly correlated with the success rate, but implant length could also be regarded as a result of the jawbone volume available. Another negative patient-related factor was the treatment protocol; however, in most cases this was also indirectly or partly related to the status of the jawbone available for implant placement. CONCLUSION: Patient selection appears to be of importance for increasing implant success rates.

Age Factors↗