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At least 109 records · Page 6Linked to original sources
PubMed2001

Clinical experiences with a new maintenance-free shock absorbing element in titanium implants.

Until now, the biokinetic elements of one implant system were to be substituted once a year in order to prevent complications of fractures of fixation screws. In this article a new implant with a maintenance-free shock absorbing element was examined. During the last 6 years, 384 dental implants with a biokinetic element (mobile-implant, SIS Inc., Klagenfurt, Austria) were placed in 138 patients. The implants were loaded with prosthetic superstructures 4 months after implantation. For comparison, 160 patients were treated with 494 conventional titanium implants of the same design without biokinetic elements. All patients were examined radiologically and clinically. Periimplant probing depth, periimplant bleeding, Periotest-values (Siemens, Bensheim, Germany) at the time of prosthetic treatment and 3, 6, 9, 12, and 24 months after implant loading were registered. Implantation was successful in 97.2% of mobile-implants and 98% of conventional implants. There was a low degree of sulcus bleeding and high degree of physiological periimplant probing depths in both patients groups. In mobile-implants, the Periotest-values were positive and similar to that of the control. There was no difference between the values in the maxilla and mandible. In the group with conventional implants, the Periotest-values were negative and showed a low degree of negativity during the first 12 months after implant loading. Periotest-values in the upper jaw were higher than in the lower jaw. There was a lower degree of periimplant bone loss after implant loading in patients with mobile-implants. In conclusion, mobile-implants demonstrate the positive effects of implants with shock absorbing elements. They are maintenance free.

Alveolar Bone Loss↗
PubMed1996

Bone formation in the goat maxillary sinus induced by absorbable collagen sponge implants impregnated with recombinant human bone morphogenetic protein-2.

This study assessed the efficacy, safety, and technical feasibility of inducing bone formation in an animal model of maxillary sinus floor augmentation using recombinant human bone morphogenetic protein-2 (rhBMP-2) impregnated on an absorbable collagen sponge (ACS). Bilateral antral maxillary sinus floor elevation procedures were surgically performed in six adult female Alpine-Saanen goats. Bone formation in response to the implant was evaluated using sequential radiographs, computerized tomography, and gross pathologic and histologic analysis performed at necropsy. Computerized tomographic scans documented nonosseous radiopacity in both sinuses postimplantation. Sinuses implanted with the rhBMP-2/ACS subsequently demonstrated increasing radiopacity local to the implant site, while radiopacity of the negative control sinuses remained unchanged or decreased. The results demonstrated the ability of an rhBMP-2/ACS implant to induce substantive new bone formation within the maxillary sinus of goats without adverse sequelae. The rhBMP-2/ACS composite implant may represent an acceptable alternative to traditional bone grafts and bone substitutes for maxillary sinus floor augmentation procedures in humans.

Animals↗
PubMed1990

Tissue reactivity and degradation patterns of absorbable vascular ligating clips implanted in peritoneum and rectus fascia.

Absorbable vascular ligating clips are finding increasing use in intraabdominal surgery. We report the results of a light and scanning electron microscope investigation of the tissue reactivity and clip degradation patterns of two such materials, Absolok (polydioxanone) and Lactomer (copolymer of glycolic and lactic acid), implanted in the fascia and peritoneum of rabbits for intervals of 2 to 70 days. Cellular response to the clips, defined as the number of inflammatory cells/10(4) microns 2, was maximum at day 4 postimplantation, then gradually declined as the duration of implantation increased. This pattern, seen with both types of clips, was similar to that seen with polydioxanone (PDS) suture, but significantly greater than that associated with polypropylene (Prolene) suture. Although cellular response to the clips was greater in peritoneum than in fascia, especially on two occasions associated with adhesion formation, this was not statistically significant. Based on our morphological observations, the signs of clip degradation which were indicated by the appearance of surface crazing and cracks occurred earlier in peritoneum than in fascia.

Abdomen↗
PubMed1999

[The role of plastic shock absorbers in dental implantation].

The mechanical behaviour of different plastics (PE, PP, PI, PA, ABS, POM) was examined by static and dynamic loading. Detection of microdeformations and photoelastic stress analysis served as the examination method. According to the results, polyethylene is unsuitable, however the other plastics, with clauses, are suitable as shock absorbers. Apart from the mechanical investigation photoelastic stress analysis also revealed the benefit of osseointegration in force transmission to the bone.

Dental Implants↗
PubMed1998

[The dynamics of energy and metabolic exchange in kidneys after the new absorbable surgical sutures "Biophil" implantation].

The influence of a new surgical absorbable material Biofil on the energetical metabolism processes, contents and ratio of the nucleic acids in the operated kidney tissue was studied in experiment. The oxidizing phosphorylation inhibition, the RNA content and RNA/DNA coefficient lowering were noted on the 14th day after the catgut thread application in a sutured tissues. The phosphorilizing respiration activation, the respiration control and RNA synthesis rising were promoted by biofil application. It had a significance for stimulation of regeneration processes in kidneys and for more early restoration of their function.

Animals↗
PubMed1986

[Implantation of UV-absorbing posterior chamber lenses].

The authors report on their experience with UV-absorbent posterior chamber IOLs (ORC) implanted between April 1, 1984 and April 1, 1985 (n = 125). Short-term complications and in particular post-operative sterile uveitis, corresponded to those in a group (n = 135) who had had regular PMMA lenses implanted. While no significant lowering of glare perception could be proved after implantation of the UV-block-lenses, color perception seemed to be more correct with these lenses. Because of the short observation time no significant statements can be made regarding the frequency of cystoid macular edema.

Aged↗
PubMed2006

Long-term in vivo degradation of poly-L-lactide (PLLA) in bone.

The use of absorbable orthopedic implants has increased substantially during the last decade. Currently, most of them are fabricated from poly-L-lactide (PLLA), its co-polymers, or mixtures with other constituents. In vivo, PLLA persists for years after its surgical role has ended, which is confirmed by a long-term histological study of PLLA implanted in sheep either as functional interference screws or nonfunctional rods. The first tissue reaction is the sequestration of the implant within new bone during the initial 3 months. After a nonreactive period, a second tissue reaction is associated with the early signs of structural disintegration of the PLLA at 1 year. Subsequently, as the polymer mass reduces, it is replaced by a relatively avascular fibrous tissue containing macrophages and having an occasional multinucleated giant cell on the implant surface. After 3 years much of the polymer is still present, although as isolated fragments. The tissue reactions can be explained in terms of the physical chemistry of PLLA degradation. Though biocompatible, the excessive longevity of PLLA and the absence of its replacement by bone, indicates that despite being satisfactory clinically, it is not an ideal implant material, and that improved absorbable materials need to be developed.

Absorbable Implants↗
PubMed2003

Deep sclerectomy in patients with capsular glaucoma.

PURPOSE: To compare the results of deep sclerectomy in capsular glaucoma (CG) with those in primary open-angle glaucoma (POAG). METHODS: This consecutive, prospective study comprised 24 CG patients (28 eyes) and 25 POAG patients (29 eyes) who underwent deep sclerectomy. Two different implants were used: either an absorbable collagen implant (Aqua-Flow) or a non-absorbable hydrophilic acrylic implant (T-Flux). The number of glaucoma medications, intraocular pressure (IOP) and complications were compared postoperatively. The definition of complete success was IOP below 19 mmHg without therapy. RESULTS: After a mean follow-up of 19.9 +/- 10.9 months (range 6-36 months) in the CG group and 16.2 +/- 10.0 months (range 6-36 months) in the POAG group, complete success was seen in 60.7% and in 37.9% of eyes, respectively (p=0.085). After adjustments for disparities in baseline characteristics, survival analysis demonstrated that success rates were better over time in CG eyes than in POAG eyes (p=0.038). At all time-points, except at 24 months, the IOP was lower in the CG group than in the POAG group. This difference was statistically significant at 1 week (p=0.050) and 3 months (p=0.006). At 18 months, the mean decrease in number of medications was 77.3% in the CG group and 65.9% in the POAG group (not statistically significant). Levelled hyphema occurred more frequently in CG eyes (35.7%) than in POAG eyes (13.8%). CONCLUSION: Capsular glaucoma patients had significantly higher success rates over time than POAG patients following deep sclerectomy with implant.

Acrylic Resins↗
PubMed1994

Economic considerations on avoiding implant removals after fracture fixation by using absorbable devices.

Pins and screws for internal fracture fixation made of absorbable polymers have been available since the latter half of the 1980s. When using these implants there is no need for a subsequent implant removal operation. During the 7-year period 1985-1991, a total of 1219 patients were treated with such absorbable fixation devices, the most common indications being displaced malleolar fractures of the ankle and fractures of the radial head. Considering the economic viewpoints, the high acquisition costs of the absorbable implants partially outweighed the benefit of avoiding all removal procedures. When all costs also for the implant removal procedure after metallic fixation were included, the average cost saved per patient by using absorbable implants in a trimalleolar fracture was FIM 2023 (4.4% of the total costs). However, the removal of metallic devices is in fact to some degree optional, and in case the metallic implants were not removed, the economic result was in favor of the metallic devices by FIM 3684 per patient. Consequently, the ultimate economic audit of the use of absorbable vs. metallic devices is linearly dependent on the actual implant removal frequency. According to the present cost analysis, the break-even point would be attained at a removal rate of 65% in trimalleolar ankle fractures, at 51% in uni-and bimalleolar fractures and at 30% in fractures of the radial head. Only at a higher removal rate the introduction of absorbable devices would be a financially more favorable alternative.

Bone Nails↗
PubMed1999

Conventional spiral and low-dose computed mandibular tomography for dental implant planning.

Absorbed doses to radiosensitive organs in the head and neck from pre-implant conventional hypocycloidal, conventional spiral and computed tomography (CT) were measured with thermoluminescent dosimeters in an anthropomorphic phantom head. From conventional tomography organ doses, except to the major salivary glands, were below 0.2 mGy. They were considerably higher with CT than conventional tomography. Tomographic images of posterior lower jaw regions were evaluated regarding measurement reliability in conventional spiral tomograms. Observers measured the distance marginal crest-mandibular canal, marked their measuring points and estimated the length of an intended Brånemark implant. The variability between observers, mainly due to the intra-observer variation, decreased with multiple readings and optimized image quality. The suggested implant length was the same as the one inserted in 70% of the cases. Tomographic images from mandibular body segments were used to test the influence of radiation exposure and scanning mode on image quality in CT and compare the quality of the CT images with that in conventional spiral tomograms. Mandibular canal and marginal bone crest visibility was unaffected by radiation dose in CT examinations. Differences among CT scanning modes and between CT and conventional spiral tomography were highly significant. Frontal CT scans or conventional spiral tomograms were preferred. In cross-sectional images of the posterior lower jaw image quality in conventional spiral and reformatted CT at 40 mAs and 80 mAs was compared. Observers graded the acceptability of images for implant planning and traced the contours of the mandibular body and canal. Conventional, spiral tomograms were subjectively preferred over reformatted CT images. Differences between CT images at different mAs settings were not statistically significant. The mandibular canal was more frequently untraceable in high-dose CT. The use of tomography for dental implant planning was studied by means of a survey among oral radiology clinics in Sweden and implantology clinics in other countries. It was used by 93.4% but varied markedly between and within anatomic regions. CT was used by 73%. Radiation doses varied considerably within and between different CT brands. The availability rather than the clinical need strongly influenced the choice of technique. From the point of view of radiation dose and information necessary for implant planning conventional spiral tomography is to be preferred over reformatted CT. However, when CT is the only technique at hand, it can be performed with a lower than standard mA-setting.

Artifacts↗
PubMed2001

Non-penetrating glaucoma surgery using AquaFlow(TM)collagen implants.

AquaFlow TM is an absorbable collagen implant for use in non-penetrating surgery for primary open angle glaucoma. Its purpose is to facilitate drainage of fluid from the eye, thereby reducing intraocular pressure. AquaFlow TM is approved for use in Canada in medically refractory cases of primary open angle glaucoma. Non-penetrating glaucoma surgery with the AquaFlow TM implant appears to be a relatively safe procedure. However, there is a steep learning curve for the surgeon and it is initially associated with a high rate of conversion to conventional surgery during the operation. Limited evidence from small non-randomized trials suggests that the AquaFlow TM implant may offer benefits over conventional surgical approaches in terms of reduced complication rates, reduced medication use, an earlier return of improved vision and sustained control of intraocular pressure. However, the efficacy and cost-effectiveness of this approach have not been established. January, 2001 for use in patients with uncontrolled

Canada↗
PubMed1994

Absorbable mesh in placement of temporary implants.

PURPOSE: To evaluate absorbable mesh for the suturing of afterloading catheters in patients with tumors involving the chest wall. METHODS AND MATERIALS: Patients underwent thoracotomy and resection of tumor; a layer of absorbable mesh was then sutured to the tumor bed. Nylon flexiguide afterloading catheters were sutured into the mesh at about 1.5 cm distance from each other. A second layer of mesh was then sutured on top of the catheters. The chest wall was closed. Orthogonal radiographs and CT scans of the area of implants were done to verify catheter position in each patient on day 1 and on the last day of implant. Computer dosimetry by digitization of dummy sources was performed on each set of radiographs. The same seed for both sets of films was chosen as the origin of digitization. All seed coordinates were compared directly to offset for any rotation of the patient during the two sets of films. The distances were calculated from all seed positions to the origin, then tabulated and compared. RESULTS: The distances agreed within a few millimeters (7-8 mm). The differences may be attributed to the patient's breathing and to the localization uncertainty. The resulting dose alteration was negligible. CONCLUSION: This technique appears to provide adequate anchorage of catheters with resulting constant seed position and dose distribution in areas of scant tissues or in surgical beds of considerable size.

Aged↗
PubMed2006

Mode superposition transient dynamic analysis for dental implants with stress-absorbing elements: a finite element analysis.

The purpose of this study was to analyze the dynamic behavior of a dental implant with a stress-absorbing element, using dynamic analysis. Two model types, stress-absorbing model with a resilient stress absorber made of polyoxymethylene and non-stress-absorbing model with rigid titanium, were employed. In both model types, the implant was 4.0 mm in diameter and 13.0 mm in length and placed in the mandibular first molar region. Shapes of the finite element implant and implant-bone were modeled using computer-aided design. All calculations for the dynamic analysis were performed using the finite element method. It was found that the stress-absorbing model had a lower natural frequency than the non-stress-absorbing model. In addition, the stress-absorbing model had a higher damping effect than the non-stress-absorbing model. It was concluded that mode superposition transient dynamic analysis is a useful technique for determining dynamic behavior around dental implants.

Dental Implants↗
PubMed2006

Accumulation of LPS by polyethylene particles decreases bone attachment to implants.

Molecules absorbed on the surface of particulate wear debris may contribute to inflammatory reactions that lead to aseptic loosening of implants. Lipopolysaccharide (LPS), a bacterial endotoxin, can attach to many biomaterials and stimulate macrophages to secrete osteoclast-activating cytokines. We tested the adsorption of LPS by polyethylene particles in vitro and examined the biological effects of LPS absorption on bone remodeling around implants in vivo. Polyethylene particles were incubated in radiolabeled LPS solutions, and adsorption of LPS by the particles was quantified by radioassay. Because polyethylene particles are hydrophobic and less dense than water, they floated and clumped when incubated in a water solution of LPS, resulting in low adsorption of LPS. However, when particles were incubated in an ethanol solution of LPS, most of the LPS was adsorbed by the particles, and was resistant to washing with water. Triton X-100 (10%), however, effectively washed the LPS off the particles. In a rat model, the presence of polyethylene particles around the implant in the femoral canal decreased bone attachment to the implant at 6 weeks. Incubating the particles with LPS before implantation, or intermittent administration of LPS systemically, further decreased bone-implant attachment to similar extents, but had no effect on the bone density of the control side femurs. Our data indicate that polyethylene particles have high affinity for LPS, depending on many factors, especially the solvents of the LPS. Intermittent systemic administration of LPS affects bone remodeling but only occurs in the area containing polyethylene particles and titanium implants, supporting the hypothesis that the presence of polyethylene particles around implants can result in accumulation of LPS from exogenous sources. This may cause local levels of LPS that are high enough to affect bone remodeling around implants.

Adsorption↗
PubMed2007

Histological biocompatibility of new, non-absorbable glaucoma deep sclerectomy implant.

We performed this study to compare the intrascleral biocompatibility of three materials: non-absorbable hydrogel contact lens polymer, non-absorbable silicone rubber, and absorbable cross-linked sodium hyaluronate. Intrascleral implantation of three different materials was performed in 13 healthy, pigmented rabbits. Implants of methacrylic hydrogel, silicone rubber, and cross-linked sodium hyaluronate were implanted in 10, 8, and 8 eyes, respectively. The animals were euthanized at 7, 30, 180, and 360 days post implantation. The eyes were enucleated and immediately fixed in 10% buffered formalin. Semithin sections were cut and stained with hematoxylin-eosin. Light microscope analysis of the specimens was performed. The least severe inflammatory reaction was observed with cross-linked sodium hyaluronate implants. The number of inflammatory cells in proximity to methacrylic hydrogel and silicone implants at all periods of follow up was similar. The thickest fibrous capsule was observed with silicone implants (average, 28.38 +/- 11.17 microm). This area was thinner with methacrylic hydrogel implants (average, 14.90 +/- 5.57 microm) and was thinnest around sodium hyaluronate implants (average, 7.21 +/- 2.33 microm). For each type of implant, the wall on the conjunctival side of the fibrous capsule was significantly thicker than the wall on the choiroidal side. The space between the implant, scleral flap, and bed was filled soon after surgery with connective tissue rich in vessels. In our study, cross-linked sodium hyaluronate had the highest intrascleral biocompatibility. Although the inflammatory responses of the sclera to methacrylic hydrogel and silicone rubber were similar in nature, a thicker fibrous capsule was generated around silicone implants.

Animals↗
PubMed1998

[Absorbable self-reinforced biomaterials used for fracture fixation implants].

A series of absorbable polymers used for osteosynthesis implants are introduced in this review. To reduce the degradation rate and increase the strength of them, some methods, such as self-reinforced or coating with other polymers, have been presented. Some clinical and animal's experiments have been discussed.

Absorbable Implants↗
PubMed1992

Absorbed dose determination for tomographic implant site assessment techniques.

A set of data to compare the absorbed dose delivered by tomographic implant site assessment techniques was generated. Absorbed doses were measured in fourteen anatomic sites from (1) computed tomography scans and (2) a series of tomographic cuts performed on a linear tomography unit. The doses to the thyroid gland, the active bone marrow, the brain, the salivary glands, and the eyes were determined with the use of a tissue-equivalent phantom with lithium fluoride thermoluminescent dosimeters at the appropriate locations.

Absorption↗