916 resultados para COATED IMPLANTS
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OBJECTIVES: To assess retrospectively, over at least 5 years, the incidences of technical and biological complications and failures in young adult patients with birth defects affecting the formation of teeth. MATERIAL AND METHODS: All insurance cases with a birth defect that had crowns and fixed dental prostheses (FDPs) inserted more than 5 years ago were contacted and asked to participate in a reexamination. RESULTS: The median age of the patients was 19.3 years (range 16.6-24.7 years) when prosthetic treatment was initiated. Over the median observation period of 15.7 years (range 7.4-24.9 years) and considering the treatment needs at the reexamination, 19 out of 33 patients (58%) with reconstructions on teeth remained free from all failures or complications. From the patients with FDPs and single unit crowns (SCs) on implants followed over a median observation period of 8 years (range 4.6-15.3 years), eight out of 17% or 47% needed a retreatment or repair at some point due to a failure or a complication. From the three groups of patients, the cases with amelogenesis/dentinogenesis imperfecta demonstrated the highest failure and complication rates. In the cases with cleft lip, alveolus and palate (CLAP) or hypodontia/oligodontia, 71% of the SCs and 73% of the FDPs on teeth (FDP T) remained complication free over a median observation period of about 16 years. Sixty-two percent of the SCs and 64% of the FDPs on implants remained complication free over 8 years. Complications occurred earlier with implant-supported reconstructions. CONCLUSIONS: Because healthy, pristine teeth can be left unprepared, implant-supported SCs and FDPs are the treatment choice in young adults with birth defects resulting in tooth agenesis and in whom the edentulous spaces cannot be closed by means of orthodontic therapy. However, the trend for earlier and more frequent complications with implant-supported reconstructions in young adults, expecting many years of function with the reconstructions, has to be weighed against the benefits of keeping teeth unprepared. In cases with CLAP in which anatomical conditions render implant placement difficult and in which teeth adjacent to the cleft require esthetic corrections, the conventional FDP T still remains the treatment of choice.
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AIM: To assess soft tissues healing at immediate transmucosal implants placed into molar extraction sites with buccal self-contained dehiscences. MATERIAL AND METHODS: For this 12-month controlled clinical trial, 15 subjects received immediate transmucosal tapered-effect (TE) implants placed in molar extraction sockets displaying a buccal bone dehiscence (test sites) with a height and a width of > or =3 mm, respectively. Peri-implant marginal defects were treated according to the principles of Guided Bone Regeneration (GBR) by means of deproteinized bovine bone mineral particles in conjunction with a bioresorbable collagen membrane. Fifteen subjects received implants in healed molar sites (control sites) with intact buccal alveolar walls following tooth extraction. In total, 30 TE implants with an endosseous diameter of 4.8 mm and a shoulder diameter of 6.5 mm were used. Flaps were repositioned and sutured, allowing non-submerged, transmucosal soft tissues healing. At the 12-month follow-up, pocket probing depths (PPD) and clinical attachment levels (CAL) were compared between implants placed in the test and the control sites, respectively. RESULTS: All subjects completed the 12-month follow-up period. All implants healed uneventfully, yielding a survival rate of 100%. After 12 months, statistically significantly higher (P<0.05) PPD and CAL values were recorded around implants placed in the test sites compared with those placed in the control sites. CONCLUSIONS: The findings of this controlled clinical trial showed that healing following immediate transmucosal implant installation in molar extraction sites with wide and shallow buccal dehiscences yielded less favorable outcomes compared with those of implants placed in healed sites, and resulted in lack of 'complete' osseointegration.
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OBJECTIVES: To assess the bleeding on probing (BOP) tendency and periodontal probe penetration when applying various probing forces at implant sites in patients with a high standard of oral hygiene with well-maintained peri-implant tissues. MATERIAL AND METHODS: Seventeen healthy patients with excellent oral hygiene in a maintenance program after having been treated for periodontitis or gingivitis were recruited. Missing teeth had been replaced using oral implants. The BOP and probing depth (PPD) were assessed at the mid-buccal, mid-oral, mesial and distal aspects of the buccal surfaces of each implant. Moreover, contralateral teeth were designated and assessed for BOP and PPD in the same locations and at the same observation visits. At each visit, implants and contralateral teeth were randomly assigned to one of the standardized probing forces (0.15 or 0.25 N). The second probing force was applied at the repetition of the examination 7 days later. RESULTS: Increasing the probing pressure by 0.1 N from 0.15 N resulted in an increase of BOP percentage by 13.7% and 6.6% for implants and contralateral teeth, respectively. There appeared to be a significant difference of the mean BOP percentage at implant and tooth sites when a probing pressure of 0.25 N was applied. A significantly deeper mean PPD at implant sites compared with tooth sites was found irrespective of the probing pressure applied. CONCLUSIONS: The results of the present study demonstrated that 0.15 N might represent the threshold pressure to be applied to avoid false positive BOP readings around oral implants. Hence, probing around implants demonstrated a higher sensitivity compared with probing around teeth.
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INTRODUCTION: Using a rat model, we evaluated the kinetics and histomorphometry of ectopic bone formation in association with biomimetic implant coatings containing BMP-2. MATERIALS AND METHODS: One experimental and three control groups were set up: titanium-alloy discs coated with a biomimetically co-precipitated layer of calcium phosphate and BMP-2 [1.7 microg per disc (incorporated-BMP group)]; uncoated discs (control); discs biomimetically coated with a layer of calcium phosphate alone (control); and discs biomimetically coated with a layer of calcium phosphate bearing superficially adsorbed BMP-2 [0.98 microg per disc (control)]. Discs (n = 6 per group) were implanted subcutaneously in rats and retrieved at 7-day intervals over a period of 5 weeks for kinetic, histomorphometrical, morphological and histochemical analyses. RESULTS: In the incorporated-BMP-2 group, osteogenic activity was first observed 2 weeks after implantation and thereafter continued unabated until the end of the monitoring period. The net weekly rates of bone formation per disc were 5.8 mm3 at 2 weeks and 3.64 mm3 at 5 weeks. The total volumes of bone formed per disc at these junctures were 5.8 mm3 and 10.3 mm3, respectively. Bone tissue, which was formed by a direct ossification mechanism, was deposited at distances of up to 340 microm from the implant surfaces. The biomimetic coatings were degraded gradually, initially by foreign body giant cells alone and then also by osteoclasts. Forty percent of the coating material (and thus presumably of the incorporated BMP-2) remained at the end of the monitoring period. Hence, 60% of the incorporated BMP-2 had been released. At this 5-week juncture, no bone tissue was associated with any of the control implants. CONCLUSION: BMP-2 incorporated into biomimetic calcium phosphate coatings is capable not only of inducing bone formation at an ectopic site in vivo but also of doing so with a very high potency at a low pharmacological level, and of sustaining this activity for a considerable period of time. The sustainment of osteogenic activity is of great clinical importance for the osseointegration of dental and orthopedic implants.
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In orthopaedic and dental implantology, novel tools and techniques are being sought to improve the regeneration of bone tissue. Numerous attempts have been made to enhance the osteoconductivity of titanium prostheses, including modifications in their surface properties and coating with layers of calcium phosphate. The technique whereby such layers are produced has recently undergone a revolutionary change, which has had profound consequences for their potential to serve as drug-carrier systems. Hitherto, calcium phosphate layers were deposited upon the surfaces of metal implants under highly unphysiological physical conditions, which precluded the incorporation of proteinaceous osteoinductive drugs. These agents could only be adsorbed, superficially, upon preformed layers. Such superficially adsorbed molecules are released too rapidly within a biological milieu to be effective in their osteoinductive capacity. Now, it is possible to deposit calcium phosphate layers under physiological conditions of temperature and pH by the so-called biomimetic process, during which bioactive agents can be coprecipitated. Since these molecules are integrated into the inorganic latticework, they are released gradually in vivo as the layer undergoes degradation. This feature enhances the capacity of these coatings to act as a carrier system for osteogenic agents.
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We have previously shown that proteins can be incorporated into the latticework of calcium phosphate layers when biomimetically coprecipitated with the inorganic components, upon the surfaces of titanium-alloy implants. In the present study, we wished to ascertain whether recombinant human bone morphogenetic protein 2 (rhBMP-2) thus incorporated retained its bioactivity as an osteoinductive agent. Titanium alloy implants were coated biomimetically with a layer of calcium phosphate in the presence of different concentrations of rhBMP-2 (0.1-10 microg/mL). rhBMP-2 was successfully incorporated into the crystal latticework, as revealed by protein blot staining. rhBMP-2 was taken up by the calcium phosphate coatings in a dose-dependent manner, as determined by ELISA. Rat bone marrow stromal cells were grown directly on these coatings for 8 days. Their osteogenicity was then assessed quantitatively by monitoring alkaline phosphatase activity. This parameter increased as a function of rhBMP-2 concentrations within the coating medium. rhBMP-2 incorporated into calcium phosphate coatings was more potent in stimulating the alkaline phosphatase activity of the adhering cell layer than was the freely suspended drug in stimulating that of cell layers grown on a plastic substratum. This system may be of osteoinductive value in orthopedic and dental implant surgery.
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PURPOSE: This retrospective study reports the clinical outcome following placement of extraoral implants in severely resorbed posterior ridges to support distal-extension removable dentures. MATERIAL AND METHODS: Consecutively treated patients with partially or completely edentulous ridges, with available bone height in the posterior region of 6 mm or less, were included in the study. Implants originally intended for extraoral use (Straumann) were placed in second molar regions and allowed to heal for 4 to 6 months before abutment connection. At recall appointments, the peri-implant hard and soft tissues were evaluated. Complications with implant components, as well as mechanical and structural failures of the prostheses, were recorded. Two-year survival rates were calculated and life table analyses undertaken. RESULTS: Twenty-nine patients (19 women and 10 men; average age 61.2 years, range, 44 to 75 years) were included in the study. Forty-seven extraoral implants in 26 patients were placed in the second molar site of the mandible. Two extraoral implants in 2 patients failed during the osseointegration phase, yielding an 8-year cumulative success rate of 91.8%. The mean distance from the extraoral implants to the most distal tooth/implant was 28.1 mm (range, 16.7 to 39.2 mm). Twenty-three extraoral implants were restored with magnets, 18 with ball anchors, and 4 with conical cylinders. Replacement of abutments and retention elements was necessary in 2 patients. Four abutments in 2 patients were disconnected from the restorations. CONCLUSIONS: Within the limits of the employed research design, extraoral implants may be used successfully to provide support for distal-extension removable dentures in severely resorbed posterior alveolar ridges.
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BACKGROUND Long-term studies of ≥10 years are important milestones to get a better understanding of potential factors causing implant failures or complications. PURPOSE The present study investigated the long-term outcomes of titanium dental implants with a rough, microporous surface (titanium plasma sprayed [TPS]) and the associated biologic and technical complications in partially edentulous patients with fixed dental prostheses over a 20-year follow-up period. MATERIALS AND METHODS Sixty-seven patients, who received 95 implants in the 1980s, were examined with well-established clinical and radiographic parameters. Based on these findings, each implant was classified as either successful, surviving, or failed. RESULTS Ten implants in nine patients were lost during the observation period, resulting in an implant survival rate of 89.5%. Radiographically, 92% of the implants exhibited crestal bone loss below 1 mm between the 1- and 20-year follow-up examinations. Only 8% yielded peri-implant bone loss of >1 mm and none exhibited severe bone loss of more than 1.8 mm. During the observation period, 19 implants (20%) experienced a biologic complication with suppuration. Of these 19 implants, 13 implants (13.7%) had been treated and were successfully maintained over the 20-year follow-up period. Therefore, the 20-year implant success rate was 75.8 or 89.5% depending on the different success criteria. Technical complications were observed in 32%. CONCLUSION The present study is the first to report satisfactory success rates after 20 years of function of dental implants with a TPS surface in partially edentulous patients.
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Although vascular endothelial growth factor (VEGF) has been described as a potent angiogenic stimulus, its application in therapy remains difficult: blood vessels formed by exposure to VEGF tend to be malformed and leaky. In nature, the principal form of VEGF possesses a binding site for ECM components that maintain it in the immobilized state until released by local cellular enzymatic activity. In this study, we present an engineered variant form of VEGF, alpha2PI1-8-VEGF121, that mimics this concept of matrix-binding and cell-mediated release by local cell-associated enzymatic activity, working in the surgically-relevant biological matrix fibrin. We show that matrix-conjugated alpha2PI1-8-VEGF121 is protected from clearance, contrary to native VEGF121 mixed into fibrin, which was completely released as a passive diffusive burst. Grafting studies on the embryonic chicken chorioallantoic membrane (CAM) and in adult mice were performed to assess and compare the quantity and quality of neovasculature induced in response to fibrin implants formulated with matrix-bound alpha2PI1-8-VEGF121 or native diffusible VEGF121. Our CAM measurements demonstrated that cell-demanded release of alpha2PI1-8-VEGF121 increases the formation of new arterial and venous branches, whereas exposure to passively released wild-type VEGF121 primarily induced chaotic changes within the capillary plexus. Specifically, our analyses at several levels, from endothelial cell morphology and endothelial interactions with periendothelial cells, to vessel branching and network organization, revealed that alpha2PI1-8-VEGF121 induces vessel formation more potently than native VEGF121 and that those vessels possess more normal morphologies at the light microscopic and ultrastructural level. Permeability studies in mice validated that vessels induced by alpha2PI1-8-VEGF121 do not leak. In conclusion, cell-demanded release of engineered VEGF121 from fibrin implants may present a therapeutically safe and practical modality to induce local angiogenesis.
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One hundred fifty crossbred yearling steers with an average weight of 876 pounds were used in a 111-day experiment. Steers received either 1) no implant and no ionophore, 2) Synovex Plus¨ and no ionophore, 3) Cattlyst¨ and no implant, 4) Synovex Plus¨ and Cattlyst¨, or 5) Revalor S¨ and Rumensin¨. Implanting steers with ) Synovex Plus¨ increased gain and improved feed efficiency compared with control steers. Compared with steers not implanted, steers implanted with Synovex Plus¨ had heavier carcasses and larger ribeye areas, but similar fat thickness and yield grades. Feeding Cattlyst¨ alone did not increase gain or improve feed conversion, but there was some improvement in feedlot performance when Cattlyst¨ was fed to steers implanted with Synovex Plus¨. Steers implanted with Synovex Plus¨ and fed Cattlyst¨ had superior gains to steers implanted with Revalor S¨ and fed Rumensin¨.
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One hundred forty-four crossbred yearling steers with an average weight of 841 pounds were used in a 116- day experiment. Steers received either 1) no implant, 2) Synovex S¨, 3) Revalor S¨, or 4) Synovex Plus¨. All implanted groups consumed more feed and gained faster and more efficiently than non-implanted steers. There were no significant differences in gain, feed intake or feed efficiency among implanted groups, though steers with the estrogen + trenbolone acetate combination implants were numerically superior to those implanted with Synovex S¨. There were no differences in feedlot performance between the two combination implants. Implants increased carcass weight with no significant effects on fat thickness or carcass quality grades. The combination implants containing trenbolone acetate increased ribeye area and increased masculinity of the carcasses. These results indicate Synovex Plus¨ is an effective implant for finishing steers.