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Biomedical subjects

U Lindén

Publications and source records attributed to U Lindén.

18 recordsLinked to original sources
PubMed2001

A retrospective analysis of factors associated with multiple implant failures in maxillae.

This retrospective study was designed to verify the factors that influence implant failures. Six prosthodontic clinics in Sweden participated in the study, and together they included a total of 54 patients treated between January 1988 and December 1996. All patients were completely edentulous in the maxilla, and received either a fixed prosthesis or an overdenture supported by at least 4 implants (Brånemark System). Half of the patients belonged to the study group, and an inclusion criterion for this group was that they had lost at least half of their implants. To reduce bias, the patients in the control group were matched to the study group, i.e. they were selected so that both groups were as identical as possible. The results of the study indicate that the control group had a better initial bone support than the study group. Furthermore, the patients in the study group suffered from circumstances that could induce implant failure, such as bruxism, personal grief, depression, as well as addictions to cigarettes, alcohol and/or narcotics. On the study form the clinicians were asked to give their own opinion of the reason for implant failure. The answers given could easily be grouped into 5 different topics, and this experience can be useful to improve patient selection. This study suggests that there are certain factors of importance to consider to prevent a cluster phenomenon of implant failures i.e. lack of bone support, heavy smoking habits and bruxism.

Adult↗
PubMed2001

Fixed mandibular restorations on three early-loaded regular platform Brånemark implants.

BACKGROUND: Originally, the Brånemark System was used as a two-stage surgical procedure. Comparable clinical results have made one-stage and early-loading concepts possible alternatives in the edentulous mandible. From the patient's point of view, the financial aspect of implant treatment is important. In an attempt to decrease financial burden, the reduction of surgical interventions and reduction of the number of implants could be considered. PURPOSE: This prospective multicenter study evaluated (1) the 1- and 3-year success rates of implants loaded within 1 month after one-stage surgery with a fixed 10- to 12-unit bridge on three regular platform Brånemark System implants in the mandible, (2) the outcome of the prosthetic treatment, and (3) the opinion of patients regarding the treatment procedure. MATERIALS AND METHODS: Of 20 patients, 19 received five implants in the mandible, of which three were functionally loaded with the one-stage technique (group 1). The loaded implants were inserted in a tripodal position, one implant in the symphysis and two located anterior of the mental foramen in the bicuspid area. Two additional implants were inserted for safety reasons but were not intended to be included in the restoration. These two additional implants served as either an unloaded one-stage control implant (group 2) or an unloaded control implant installed with the submerged technique (group 3). Immediately after surgery, the implants were loaded with a relined denture. The patients received a 10- to 12-unit prosthetic reconstruction an average 31 days (range, 4-53 d) after surgery. Implant stability was clinically checked at 3, 12, and 36 months. Radiographs were taken at corresponding follow-up visits to calculate bone-to-implant level and marginal bone resorption. RESULTS: Six of 60 functionally loaded implants (10%) and 3 of 20 prostheses (15%) failed within the first year. The cumulative implant failure rate in group 1, both after 1 and after 3 years, was 9.5%. No implant failure occurred in the control groups 2 and 3. The average marginal bone level measured at 1 and 3 years was 1.6 mm (SD = 0.8 mm) and 2.1 mm (SD = 0.2 mm), respectively, for group 1; 1.5 mm (SD = 1.3 mm) and 2.4 mm (SD = 0.6 mm), respectively, for group 2; 0.8 mm (SD = 1.4 mm) and 0.7 mm (SD = 0.9 mm), respectively, for group 3. CONCLUSIONS: The results of treatment using three regular platform Brånemark System implants supporting a fixed mandibular arch reconstruction were less favorable than the outcome that can be expected with a standard four- to six-implant with one-stage surgery.

Adult↗
PubMed2000

Quality of fixed restorative treatment on Brånemark implants. A 3-year follow-up study in private dental practices.

The aim of the present prospective study were to describe the quality of implant supported reconstructions made by dentists previously inexperienced with implant prosthodontics and to evaluate alterations and complications from the moment of insertion to 3 years later. Before starting with the prosthodontic work, the dentists had participated in a 2-day postgraduate course focusing on planning and practical training. Forty-nine patients were clinically examined within 4 months after insertion of the fixed implant supported prosthesis. Three years later 39 of the 49 participants underwent a second examination by the same independent examiner. Thirty-one patients had a complete rehabilitation (25 with resin teeth bonded to a metal framework and 6 ceramo-metal bridges); 8 patients had partial ceramo-metal reconstructions. The parameters assessing the quality of the restoration were design, fit, occlusion/articulation and esthetics. Oral hygiene and health of the peri-implant tissues were also examined. Each parameter was scored as perfect, acceptable, to be corrected or to be redone. These scores were a modification of "The guidelines for the assessment of clinical quality and professional performance of the Californian Dental Association". The initial prosthodontic quality was rated perfect to acceptable except for one restoration which had an unacceptable fit and had to be modified. After 3 years of function the quality did not change except for esthetics which worsened for resin bonded teeth (P < 0.05). The esthetic appearance of ceramo-metal reconstructions were unaltered. The peri-implant condition was predominantly healthy and stable during 3 years. The conclusion of the present study is that dentists previously inexperienced with implant prosthodontics implemented the information from a training course satisfactorily. They were able to make a clinically acceptable restoration with a quality that was stable after 3 years except for discoloration in resin bonded teeth. This, however, had no effect on patient's opinion and satisfaction.

Clinical Competence↗
PubMed1999

Clinical outcome of Screw Vent implants. A 7-year prospective follow-up study.

The clinical results of 85 Screw Vent implants are described with respect to 7-year success, including radiographically detectable bone loss, survival and prosthetic quality. The 1-year results of the same material have been reported previously (De Bruyn et al. 1992). Implants were considered as successful when they were meeting with the success criteria proposed by the European Academy for Periodontology. From the 85 implants originally installed, 16 failed during the 7-year interval (18.8%), 6 were unaccounted for (7%), 21 (24.7%) did not meet the success criteria yet survived and 42 implants (49.4%) were successful. The success rate was 65.2% for the mandibular and 43.5% for the maxillary implants. Implant failures were irrespective of implant length, smoking habits, prosthetic quality or oral hygiene level. From 24 patients with a corresponding number of 60 implants, radiographs were available for bone loss analysis. The mean bone loss after 7 years was 2.92 mm (range -0.5 to 6.3) 18 out of 60 examined implants (30%) showed unacceptable radiological bone loss beyond the critical value of 2.7 mm. Implant material analysis and histomorphometric analysis of a retrieved implant are discussed. In the present clinical study, the Screw Vent implant system does not meet the success criteria proposed by the European Academy for Periodontology. The ongoing bone loss increases the risk for future implant failures and peri-implant disease.

Alveolar Bone Loss↗
PubMed1997

Patient's opinion and treatment outcome of fixed rehabilitation on Brånemark implants. A 3-year follow-up study in private dental practices.

In this study, patient opinion on oral rehabilitation by means of Brånemark implants was investigated. All patients were referred to a periodontal clinic for implant installation and treated by one and the same operator. Prosthetic restorations were performed by dentists, who had no previous experience with prostheses on implants, but had completed a postgraduate training course. Patient opinion was obtained through questionnaires, pertaining to satisfaction and oral function. A comparison was made between pre-implant situation, short-term (< 4 months) and long-term functioning (3 years) with the implant-restorative rehabilitation. In total, 61 patients participated in the study; 23 received a full lower arch bridge and 18 a full upper arch bridge, while 20 patients got partial bridges. Of 298 installed implants, 7 failed at abutment connection (2.3%) and 1 during the 3-year follow-up interval (0.3%). The study results indicated that a great majority of patients were very satisfied with the treatment. Comfort with eating, aesthetics, phonetics and overall satisfaction improved significantly and nearly all patients said that they would undergo the treatment again or recommend it to others. Patients experienced their implants as "natural" teeth. The conclusion is that rehabilitation ad modum Brånemark, even in the hands of non-specialized dentists, can be of high quality, improving oral function and satisfying the needs and demands of patients.

Adaptation, Psychological↗
PubMed1993

On clinical loading of osseointegrated implants. A methodological and clinical study.

Strain gauges were used to record in vivo and in vitro functional deformations in a fixed prosthetic appliance supported and retained by osseointegrated titanium implants. Four linear gauges were attached to each of totally 5 implant abutment cylinders and gauge signals were transferred into a computer via a digital converter. A computer program (ASYST) was used for collection, calibration and analysis of data obtained. Based on the results of a series of explorative in vitro tests, in vivo experiments were performed at maximum biting as well as during chewing on certain normally available food items. The results show fundamental differences between in vitro and in vivo testing conditions. Unexpectedly high bending of the implants was recorded in many of the in vivo loading situations.

Aged↗
PubMed1993

Periodontal indices around natural and titanium abutments: a longitudinal multicenter study.

This multicenter prospective study on the use of an implant system involved 9 centers and reports on the periodontal aspects after 3 years of observation. A total of 558 implants in 159 patients with 197 bridges all independent from natural teeth were originally included. Because of failures and patient withdrawals the number of implants was reduced to 460 and bridges to 174. The cumulative success rate for implants, starting from implant placement, is 94.3% after 2 years and 93.9% after 3 years indicating a leveling of implant loss. Failures concentrated in patients with a high plaque index. The loss of marginal bone was during the second and third years only 0.03 mm per year as an average while it was 0.4 mm during the first year. There were no reports of intense gingival inflammation in any of the patients and the plaque and gingivitis index behaved similarly around abutments and teeth. The probing pocket depth was significantly reduced over the observation time. The resistance towards marginal bone loss around these implants confirms the previous studies on fully edentulous patients.

Adolescent↗
PubMed1992

A comparative study of the clinical efficacy of Screw Vent implants versus Brånemark fixtures, installed in a periodontal clinic.

The clinical success of 85 Screw Vent and 107 Brånemark implants, consecutively installed in a private periodontal clinic under the same conditions and by the same operator, is compared. Mobile implants were removed and considered as failures. Intra-oral radiographs were assessed for the presence of peri-implant radiolucencies and for analysis of bone loss after functional loading. 85 Screw Vent implants were installed in 31 patients. Of 23 implants installed in 9 mandibles, none failed after 16.8 (range 12-25) months of function. Of 62 Screw Vent implants installed in 23 maxillae, 6 failed at abutment connection, 1 failed after 2 months and 2 after 13 months of function. The absolute failure rate after 13.2 (range 6-24) months was 9/62. Mean loss of bone was 1.47 mm (-1.0- +4) after 12 months of functional loading. 107 Brånemark fixtures were installed in 25 patients. Of 51 fixtures inserted in 12 mandibles, none failed; of 56 fixtures installed in 13 maxillae 1 failed before and 2 failed during abutment connection. The absolute failure is 3/56. All remaining fixtures were immobile after loading. 13 fixtures were more than 6 months in function. Only short-term comparison between both systems is possible because the observation time is longer for the Screw Vent implants. In the 1st year, only 1 implant system was available to the periodontist. Short-term comparison reveals 11.3% versus 5.3% of cumulative failure after 6 months for the Screw Vent and Brånemark implants, respectively. The results indicate that clinical efficacy is as effectively obtained with Screw Vent as with Brånemark implants in the mandible. The outcome of treatment with Screw Vent implants in the maxilla seems less predictable.

Adult↗
PubMed1991

Mechanical properties of bone cement. Importance of the mixing technique.

The compressive and shear strength and the modulus of elasticity were studied in three different bone cements (CMW, Simplex P, and Zimmer low-viscosity cement). One hundred four specimens were prepared by either a conventional manual mixing technique or mechanical vibration. Mechanical mixing gave a significant increase in shear strength for CMW and Simplex P. The compressive strength of Simplex P and Zimmer low-viscosity cement was significantly improved by mechanical mixing. The scatter of the results was significantly reduced by mechanical mixing. The modulus of elasticity was significantly increased by mechanical mixing for the three cements. The uniformity of the bone cement mass seems to be increased by a standardized mechanical mixing technique.

Bone Cements↗
PubMed1989

Fatigue properties of bone cement. Comparison of mixing techniques.

A four-point bending test was made on 54 specimens of CMW, Simplex P, and Zimmer LVC bone cements. The samples were cyclically loaded at a stress level of 20 MPa at a frequency of 4 Hz. The different cements were mixed either by hand or mechanically with or without a 0.15-bar vacuum. Mechanical mixing in a vacuum improved all three cements, and was the best of all the tested mixing techniques. Simplex P showed the best fatigue properties regardless of mixing technique.

Bone Cements↗
PubMed1989

Air inclusion in bone cement. Importance of the mixing technique.

The amount of air inclusion in bone cement (Simplex P) expressed as density and porosity was analyzed for five different mixing conditions: manual, mechanical, centrifuged manual, centrifuged mechanical, and mechanical in combination with vacuum. Mechanical mixing resulted in a cement of less porosity and increased density. Centrifugation did not further improve the cement. Mechanical mixing in combination with vacuum was superior to the other techniques in density and porosity.

Air↗
PubMed1988

Mechanical versus manual mixing of bone cement.

Conventional mixing of three different bone cements (CMW, Simplex P, and Zimmer LVC) was compared with a mechanical technique with respect to porosity and density. Density was increased in all the mechanically mixed cements, and the percentage porosity was diminished for CMW and Simplex P.

Acrylic Resins↗
PubMed1988

Low back pain during pregnancy.

All pregnant women from a well defined area (the central district of the County of Ostergötland, Sweden) attending antenatal clinics over a period of seven months were interviewed with regard to low back pain during pregnancy. Of 862 women who answered the questionnaires, about half developed some degree of low back pain. Seventy-nine women who were unable to continue their work because of severe low back pain were referred to an orthopedic surgeon for an orthoneurologic examination. The most common reason for severe low back pain was dysfunction of the sacroiliac joints. Physically strenuous work and previous low back pain were factors associated with an increased risk of developing low back pain and sacroiliac dysfunction during pregnancy.

Back Pain↗
PubMed1988

Porosity in manually mixed bone cement.

Forty-six samples of acrylic cement mixed by seven nurses were analyzed for porosity by correlated roentgenograms and microscopy studies. Mean porosity was 26.7 vol % +/- 9.21 vol % with large variations among specimens. There was also a gross variation of the pore size. The pore size exceeded 300 micron in 23% of the specimens, with a wide scatter of percentage porosity produced by each nurse. A manual mixing technique lacks reproducibility and produces cements with uncontrollable porosity.

Air↗
PubMed1985

Internal neurolysis or ligament division only in carpal tunnel syndrome--results of a randomized study.

In a series of patients with clinically and neurophysiologically well defined carpal tunnel syndrome a randomization has been made into two groups, one for operation with internal neurolysis and a microscopical technique, and the other group for cutting of the carpal ligament (flexor retinaculum) alone. The two groups have been compared postoperatively regarding clinical and neurophysiological parameters. All patients improved, 89% in both groups considered themselves totally free of symptoms at follow-up examinations but there was no significant difference in any parameter between the two groups. As a conclusion the use of internal neurolysis cannot be recommended as a routine procedure in carpal tunnel syndrome.

Adult↗
PubMedDate not supplied

Survival of the Brånemark implant in partially edentulous jaws: a 10-year prospective multicenter study.

A total of 127 partially edentulous patients, treated according to the Brånemark protocol, was followed for 10 years after completion of prosthetic treatment. The patients ranged in age from 18 to 70 years, and 57% were female. Four hundred sixty-one implants were placed in 56 maxillae and 71 mandibles. In 125 patients, 163 fixed partial prostheses were attached to the implants; a majority of the prostheses (83%) were located in posterior regions. At the end of the 10-year period, 73% of the implants could be traced either as failed or in function, providing cumulative implant survival rates of 90.2% and 93.7% for the maxilla and mandible, respectively. Of the original fixed prostheses, 63% (cumulatively 86.5%) were still in use, whereas the level of continuous cumulative prosthesis function, including primary and remade restorations, was 94.3% at the end of the evaluation period. Marginal bone resorption at the implants was low (mean = 0.7 mm), and mucosal health was good. No severe complications apart from the above-mentioned implant and prosthetic failures were reported. The Brånemark Implant System is a safe and predictable method for restoring partially edentulous patients, as demonstrated by this 10-year follow-up investigation.

Adolescent↗