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Maxillary sinus augmentation using prehardened calcium sulfate: a case report.

Prehardened medical-grade calcium sulfate hemihydrate was placed as a grafting material for sinus floor elevation in the left posterior maxilla. After 8 months of healing, three titanium plasma-sprayed screw implants (Biolock) were placed. At the same time, a bone biopsy was harvested for histologic evaluation. The specimen was processed according to standard techniques for hard tissue histology. In both the grafted area and the previously existing area of sinus floor, the histology showed complete calcium sulfate resorption and the bone was primarily of lamellar structure. In the 5-month radiograph, a new trabecular design appeared from the periphery of the grafted area, and on the 8-month radiograph, the graft material was no longer detectable and the augmented area was filled by new tissue showing a trabecular design. This case report documented that medical-grade calcium sulfate hemihydrate, when used as a grafting material for augmentation of the sinus floor, may lead to proper osseointegration of dental implants.

Absorbable Implants↗

Chondral injury from bioabsorbable screws after meniscal repair.

A case of chondral injury after medial meniscal repair with a headless bioabsorbable screw is reported. As these implants can take a long time to be absorbed, all arthroscopic surgeons should be aware of possibility of this complication during this period.

Absorbable Implants↗

[Semirigid plate osteosyntheses using absorbable polymers as temporary implants. II. Animal experiment studies].

Polylactide-l test rods showed an initial stability of 130 N/mm2 in the three-point bending test; the stability decreased after implantation in the dorsal muscle of the rat within 5 weeks to about half the initial value. The copolymer materials showed less initial strength, and the stability decreased under the same conditions much earlier. All materials showed good tissue compatibility. After a transverse section of the beagle radius was stabilized with plates and screws out of polylactide-l, a delayed bony union with callus formation was observed.

Absorption↗

[Semirigid plate osteosyntheses using absorbable polymers as temporary implants. I. Introduction, chemical composition and material-related studies].

Possible indications for the use of biodegradable implants are presented and the chemical compounds in question are briefly described. The results of a laboratory investigation to determine mechanical stability, tensile strength and molecular weight are reported, in order to characterize the polymers and co-polymers of the lactide under study.

Absorption↗

[Dosage and kinetics of MMC release of a collagen implant used as a delivery device in glaucoma surgery in the rabbit eye].

PURPOSE: To determine the absorption and the release of mitomycin-C from a collagen implant and tissue impregnation in the anterior structures of the rabbit eye. METHODS: Determining the quantity of mitomycin-C that a collagen implant can absorb with the difference between dry and soaked weight. Mitomycin-C release was measured in vitro using spectrophotometry. The measurement was repeated using a bioassay. Ocular tissue impregnation was determined in 12 eyes of six rabbits. Sclera, implant, aqueous, and ciliary body specimens were collected for concentration measurement using HPLC from 1 to 6 h after surgery. RESULTS: The mean mitomycin-C quantity absorbed in the implant was 3.22+/-0.2 microg. In vitro release was 0.13 mg/ml after 10 min and 0.05 microg/ml at 6 h. The bioassay showed almost no antifibrotic activity in sclera. In vivo release of mitomycin-C was high from the first to the sixth hour. CONCLUSION: After filtering surgery, mitomycin-C in the collagen implant is clearly released and ocular tissues are effectively impregnated.

Animals↗

Bioresorbable polymers in trauma and bone surgery.

During the last few decades interest in resorbable polymeric materials has been steadily increasing. As with other materials for implantable devices, they have to satisfy several biological and technical requirements. Implants should maintain adequate mechanical properties in vivo for the time required and degrade at an effective rate. The conditions of polymer synthesis, further processing into implants and the sterilization process determine the mechanical properties of resorbable implants. Degradation of implants is manifested by implant fragmentation, strength loss and the decrease of polymer molecular weight. The rate of degradation and the tissue reaction are strongly affected by the material chemical composition and to some extent also by the mechanical properties. Potentially, devices made from bioresorbable polymers can overcome problems associated with metal implants like stress protection, potential for corrosion, wear and debris formation, as well as the necessity of implant removal. Resorbable polymers have proven to be good materials for a range of devices in trauma surgery. However, modifications and optimizations are still required. Three-dimensional porous scaffolds in various geometrical forms offer a good potential for the manufacture of tissue-engineered implants in the future.

Absorbable Implants↗

The treatment of chronic osteomyelitis with a biodegradable antibiotic-impregnated implant.

The use of local antibiotics from a biodegradable implant for chronic osteomyelitis is an attractive alternative. The implant delivers high tissue levels, obliterates dead space, aids bone repair and does not need to be removed. The purpose of this paper is to review our early clinical experience with custom-made calcium sulfate (Osteoset bone void filler) antibiotic-impregnated implants.

Absorbable Implants↗

Biomechanical properties in titanium implants with integrated maintenance free shock absorbing elements.

Good functional properties are essential in dental implantology. Bio-kinetic elements are imitating dental resilience. In this study a new kind of implants with maintenance free shock absorbing elements will be introduced and their bio-mechanic properties reported. The mobile implant (SIS Inc., Klagenfurt, Austria) is a self-cutting conical screw implant with an integrated bio-kinetic element. The shock absorber is a central part of the implant and a titanium ring closes the shock absorbing unit within the implant. The resilience of the implant was tested by axial and horizontal loading in a special testing unit. Furthermore, a survival test of the elastic titanium ring in the most exposed cervical part of the implant was performed. The region was examined by electron microscopy after 12 million movements in the axial and horizontal direction. A progressive shock absorption was registered during horizontal and axial movements. The maximum movements were 0.06 mm in the axial and 0.16 mm in the horizontal direction. There were seen no signs of material destruction in the electron microscopic analysis. A maintenance-free bio-kinetic implant with progressive shock absorbing qualities was registered.

Biomechanical Phenomena↗

[Usefulness of selected parameters from the diagnostic laboratory for evaluating absorbed grafting materials].

The results of hematologic, biochemical research and research of clotting system after intraperitoneal implantation of absorbed synthetic threads Dexon S are presented in this work. The research was made on rats of Wistar type. Blood for the research was taken 3, 7, 14, 30 and 60 days after the implantation. Morphology (Ht, Hb, MCH, WBC, the number of platelets), activity of aspartic and alanine aminotransferase and antithrombin activity, concentration of comolete protein and its fraction and concentration of glucose, urea, creatinine and also concentration of ions Na+, K+, Mg2+, Ca2+ and fibrinogen, protein C3 and C4 of complement system as well as kaolin-kephalin time and prothrombin time of plasma were marked. On the basis of the obtained results of the research it was noticed that the used methods of research constitute supplement of biological estimation of absorbed grafting materials.

Absorption↗

Reconstructive septal surgery.

To attain without compromise the surgical goal, a straight and concurrently solid septum, especially in cases of marked deviations or severe post-traumatic deformities (sometimes combined with external deformities), an excellent proven and well-known technique is extracorporal or external septoplasty. Surgery consists of excision of the quadrilateral cartilage and its division into straight fragments. To avoid postoperative sequelae such as saddling, the pieces of cartilage must be reconnected meticulously to form a straight and at the same time solid plate. This difficult and time-consuming procedure can be assisted by the use of a connecting material. Since 1996 we have been using a polydioxanone foil (PDS, Ethicon Norderstedt Germany) as the supporting material for this purpose. The PDS as well as the suture material is completely resorbed within 5 months, excluding long-term complications of other artificial implants.

Absorbable Implants↗

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↗

[Troublesome radiologic changes after reconstructive fixation of the anterior cruciate ligament with resorbable interference screws].

The authors report worrisome radiological changes which were noted after implantation of absorbable interference screws in ligamentoplasty at the knee joint. Seventeen screws were implanted between September 1995 and July 1996, in eleven patients (average age 27) who were operated upon for chronic anterior knee instability. They underwent a modified Kenneth Jones procedure using autografts with absorbable interference screws (Acufex in 2 cases and Bio-interférix in 9 cases). Significant enlargement of bone tunnels and bony sclerosis of their edges were noted in every patient, but without any modification in the positioning of the graft. No clinical instability was observed in any of the patients, with one to two years follow-up. Publications on this topic are scarce except for one author who reported enlargement of bone tunnels after using bone-patellar tendon-bone allografts. Resorption of absorbable screws probably induces a marked inflammatory reaction, with radiological changes reminiscent of those sometimes observed after tendon allografts. Although the radiological changes reported here may not affect the graft fixation, the authors have reverted to using metallic interference screws.

Absorption↗

Computed tomography treatment planning in IR-192 brachytherapy in the head and neck.

Brachytherapy dose prescription and treatment planning lag behind the state-of-the-art for external beam therapy. As altered fractionation of external beam therapy improves patient outcome in head and neck cancer, there will be an increased need to compare the two radiotherapy techniques. Currently, implant techniques and dose prescription documentation are not uniform, dose prescription to a target volume is subjective, and implant quality is poorly understood and not routinely assessed. All contribute to a lack of scientifically rigorous brachytherapy clinical trials. Studies designed to combine tumor imaging and dosimetry data are important in the evolution of brachytherapy treatment planning. Head and neck implants, which often require nonparallel, arching, or looping source carriers for all but small tumors in order to encompass the target volume adequately, were used to evaluate the clinical utility and feasibility of computed tomography as a treatment planning tool in brachytherapy. Following placement of plastic afterloading tubes under general anesthesia, orthogonal radiographs with dummy sources in the afterloading tubes are obtained as customary for source localization. With the patient in the same position, axial CT scans are obtained with the dummy seeds still in place for treatment planning. The implant physician, using data from the pre-treatment diagnostic CT scan, outlines target areas on sequential images creating a 3-dimensional target volume. By superimposing anatomic data with isodose curves one can objectively define implant parameters important in clinical trials analysis. These include minimum target absorbed dose, implant uniformity, and treatment to target volume ratio. The results of the first 10 patients are presented and implications of these data regarding the analysis of implant technique, implant quality, and implant optimization are discussed. The technique as performed is laborious but practicable in the clinical research setting of head and neck implant. Further research efforts should improve, simplify, and objectify brachytherapy and hasten the time when rigorous multi-institutional brachytherapy trials will be reality.

Adult↗

Effect of intracanalicular collagen implants on the absorption of topically applied sodium fluorescein.

Absorbable intracanalicular collagen implants were placed in both canaliculi of one eye of nine human volunteers. The other eye served as a control. Twenty-four hours later 2% sodium fluorescein was placed into both conjunctival sacs. Serial corneal fluorescein concentrations were measured with a scanning ocular fluorophotometer from 2 to 90 min after fluorescein administration. The mean corneal fluorescein concentration averaged over all time points was greater in 7 of 9 eyes with collagen implants compared to unimplanted controls. When the data from each subject were analyzed collectively, the mean corneal fluorescein concentration in the implanted eyes (1,218 micrograms/ml +/- SEM 83) was significantly greater (p less than 0.001) than the mean concentration in the control eyes (823 micrograms/ml +/- SEM 83). The use of absorbable intracanalicular collagen implants may increase the bioavailability of topically applied ocular solutions.

Absorption↗