| 1. |
- Abtahi, Jahan, et al.
(författare)
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A bisphosphonate-coating improves the fixation of metal implants in human bone. A randomized trial of dental implants
- 2012
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Ingår i: Bone. - : Elsevier. - 8756-3282 .- 1873-2763. ; 50:5, s. 1148-1151
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Tidskriftsartikel (refereegranskat)abstract
- Many surgical procedures use metal implants in bone. The clinical results depend on the strength of the bone holding these implants. Our objective was to show that a drug released from the implant surface can improve parameters reflecting the quality or amount of this bone. Sixteen patients received paired dental titanium implants in the maxilla, in a randomized, double-blinded fashion. One implant in each pair was coated with a thin fibrinogen layer containing 2 bisphosphonates. The other implant was untreated. Fixation was evaluated by measurement of resonance frequency (implant stability quotient; ISQ) serving as a proxy for stiffness of the implant-bone construct. Increase in ISQ at 6 months of follow-up was the primary variable. None of the patients had any complications. The resonance frequency increased 6.9 ISQ units more for the coated implants (p = 0.0001; Cohens d = 1.3). The average difference in increase in ISQ and the effect size, suggested a clinically relevant improvement. X-ray showed less bone resorption at the margin of the implant both at 2 months (p = 0.012) and at 6 months (p = 0.012). In conclusion, a thin, bisphosphonate-eluting fibrinogen coating might improve the fixation of metal implants in human bone. This might lead to new possibilities for orthopedic surgery in osteoporotic bone and for dental implants.
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| 2. |
- Abtahi, Jahan, et al.
(författare)
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Bisphosphonate coating might improve fixation of dental implants in the maxilla: A pilot study
- 2010
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Ingår i: International Journal of Oral and Maxillofacial Surgery. - : Elsevier Science B.V., Amsterdam. - 0901-5027 .- 1399-0020. ; 39:7, s. 673-677
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Tidskriftsartikel (refereegranskat)abstract
- This pilot study evaluates the clinical stability of bisphosphonate-coated dental implants placed using a two-stage surgical procedure in five patients. Each patient received seven regular Brånemark implants, one of which was coated with bisphosphonate in a fibrinogen matrix. The coated implant was inserted where the bone was expected to have the least favourable quality. The level of the marginal bone around each implant was measured by intraoral periapical radiographs and implant stability was recorded using resonance frequency measurements. Frequency values (ISQ) were obtained peroperatively before flap closure and after 6 months at abutment connection. At abutment connection the bisphosphonate-coated implants were removed en bloc in two patients for histological examination. An animal experiment had previously confirmed that gamma-sterilization did not reduce bioactivity of the bisphosphonate coating. In each patient, the bisphosphonate-coated implant showed the largest improvement in ISQ level of all implants. Their values at the start tended to be lower, and the absolute value at 6 months did not differ. No complications occurred with the coated implants. Histology showed no abnormalities. Improvement in ISQ values was an expected effect of the bisphosphonate coating, but could be due to the choice of insertion site. This finding warrants a randomized, blinded study.
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| 3. |
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| 4. |
- Agholme, Fredrik, et al.
(författare)
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Local bisphosphonate release versus hydroxyapatite coating for stainless steel screw fixation in rat tibiae
- 2012
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Ingår i: Journal of materials science. Materials in medicine. - : Springer Verlag (Germany). - 0957-4530 .- 1573-4838. ; 23:3, s. 743-752
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Tidskriftsartikel (refereegranskat)abstract
- Implant fixation in bone can be improved by a coating that delivers bisphosphonates locally, or by a hydroxyapatite (HA) coating. In this study, we compared these different types of coatings. For mechanical testing, 30 rats were assigned into three groups, and similar screws were implanted bilaterally in the proximal tibiae. The rats received screws that were either uncoated, coated with nano-crystalline hydroxyapatite or coated with a bisphosphonate releasing protein matrix. After 4 weeks, one screw was subjected to pull-out testing, and the contra-lateral one to torsion testing. For morphology, 30 rats were assigned to similar treatment groups, but received only one screw each. Bisphosphonates enhanced the pull-out force by 41% (P = 0.02) compared to controls, HA increased the pull-out force although not significantly. Conversely, HA increased the maximal torque by 64% (P = 0.02). Morphometry showed higher bone volume around bisphosphonate screws in comparison to HA-coated screws (P andlt; 0.001) and controls (P andlt; 0.001). The results suggest that bisphosphonates improve fixation by increasing the amount of surrounding bone, whereas HA mainly improves bone to implant attachment.
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| 5. |
- Al-Asfour, Adel, et al.
(författare)
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Histologic analysis of a novel extracellullar matrix membrane for guided bone regeneration: an experimental study in rabbits.
- 2013
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Ingår i: The International journal of periodontics & restorative dentistry. - : Quintessence Publishing. - 1945-3388 .- 0198-7569. ; 33:2, s. 177-83
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Tidskriftsartikel (refereegranskat)abstract
- This experiment was conducted to study the histologic feasibility and biologic impact of Ti02 impregnation of an extracellullar matrix (ECM) membrane in guided bone regeneration. Eighteen adult New Zealand White rabbits were used. Bilateral bone defects were created in edentulous areas of the maxilla. The defects were filled with demineralized freeze-dried bone (DFDB). ECM was randomly pretreated with a suspension containing saline and 3 mg Ti02 granules. A regular ECM membrane served as a control on the contralateral side. Healing periods were 2, 4, and 8 weeks. Histologic and histomorphometric analyses were performed. The parameters assessed were (1) zone of inflammatory cells adjacent to ECM membrane, (2) presence of cellullar ingrowth into ECM, and (3) presence of Ti02 particles within the ECM barrier membrane. In general, no adverse reactions toward both groups of ECM membranes could be noted. The Ti02 particles remained within the ECM after 8 weeks of healing, making histologic detection of ECM easy. Histomorphometric analysis revealed low numbers of inflammatory cells adjacent to the ECM surface and adequate preservation and integration of the barrier. Contrasting Ti02 particles impregnated into the ECM membrane can be a very useful tool for the detection of similar biologic materials in in vivo models.
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| 6. |
- Albrektsson, Tomas, 1945, et al.
(författare)
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An Imbalance of the Immune System Instead of a Disease Behind Marginal Bone Loss Around Oral Implants: Position Paper
- 2020
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Ingår i: The International journal of oral & maxillofacial implants. - : Quintessence Publishing. - 1942-4434 .- 0882-2786. ; 35:3, s. 495-502
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The purpose of this paper is to present evidence that supports the notion that the primary reason behind marginal bone loss and implant failure is immune-based and that bacterial actions in the great majority of problematic cases are of a secondary nature. MATERIALS AND METHODS: The paper is written as a narrative review. RESULTS: Evidence is presented that commercially pure titanium is not biologically inert, but instead activates the innate immune system of the body. For its function, the clinical implant is dependent on an immune/inflammatory defense against bacteria. Biologic models such as ligature studies have incorrectly assumed that the primary response causing marginal bone loss is due to bacterial action. In reality, bacterial actions are secondary to an imbalance of the innate immune system caused by the combination of titanium implants and ligatures, ie, nonself. This immunologic imbalance may lead to marginal bone resorption even in the absence of bacteria. CONCLUSION: Marginal bone loss and imminent oral implant failure cannot be properly analyzed without a clear understanding of immunologically caused tissue responses.
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| 7. |
- Albrektsson, Tomas, 1945, et al.
(författare)
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Implications of considering peri-implant bone loss a disease, a narrative review
- 2022
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Ingår i: Clinical Implant Dentistry and Related Research. - : Wiley. - 1523-0899 .- 1708-8208. ; 24:4, s. 532-543
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Tidskriftsartikel (refereegranskat)abstract
- Background Peri-implantitis has been suggested to cause significant increasing proportions of implant failure with increasing time. Purpose To assess whether implant failure rates in long term studies are matching the supposed high prevalence of peri-implantitis. Material and Methods This paper is written as a narrative review of the long-term clinical investigations available in the literature. Results Some implant systems have seen unacceptable marginal bone loss figures with time coupled to increased implant failure rates, resulting in the withdrawal of these systems. The reasons for such mishap are generally unknown, with the exception of one system failure that was found to be due to improper clinical handling. Modern, moderately rough implant systems have functioned excellently over 10-15 years of follow up with minor problems with marginal bone loss and implant failure rates within a few per cent. Machined implants have functioned adequately over 20-30 years of follow up. Implant failures occur predominantly during the first few years after implant placement. No significant increase of implant failures has been observed thereafter over 20-30 years of follow up. Over the years of our new millennium, scientific and technical advances have allowed the discovery of numerous molecular pathways and cellular interactions between the skeletal and immune system promoting the development of the interdisciplinary field called osteoimmunology. Nowadays, this knowledge has not only allowed the emergence of new etiologic paradigms for bone disease but also a new dynamic approach on the concept of osseointegration and MBL around oral implants, re-evaluating our older disease oriented outlook. This facilitates at the same time the emergence of translational applications with immunological perspectives, scientific approaches based on omics sciences, and the beginning of an era of personalized dental implant therapy to improve the prognosis of oral implant treatment. Conclusions Oral implant systems have been found to function with very good clinical outcome over follow-up times of 20-30 years. Registered implant failures have occurred predominantly during the first few years after implantation, and there has been no significant increase in late failures due to peri-implantitis.
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| 8. |
- Albrektsson, Tomas, 1945, et al.
(författare)
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On inflammation-immunological balance theory—A critical apprehension of disease concepts around implants: Mucositis and marginal bone loss may represent normal conditions and not necessarily a state of disease
- 2019
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Ingår i: Clinical Implant Dentistry and Related Research. - : Wiley. - 1523-0899 .- 1708-8208. ; 21:1, s. 183-189
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Tidskriftsartikel (refereegranskat)abstract
- Background: Oral implants have displayed clinical survival results at the 95%-99% level for over 10 years of follow up. Nevertheless, some clinical researchers see implant disease as a most common phenomenon. Oral implants are regarded to display disease in the form of mucositis or peri-implantitis. One purpose of the present article is to investigate whether a state of disease is necessarily occurring when implants display soft tissue inflammation or partially lose their bony attachment. Another purpose of this article is to analyze the mode of defense for implants that are placed in a bacteria rich environment and to analyze when an obtained steady state between tissue and the foreign materials is disturbed. Materials and Methods: The present article is authored as a narrative review contribution. Results: Evidence is presented that further documents the fact that implants are but foreign bodies that elicit a foreign body response when placed in bone tissue. The foreign body response is characterized by a bony demarcation of implants in combination with a chronic inflammation in soft tissues. Oral implants survive in the bacteria-rich environments where they are placed due to a dual defense system in form of chronic inflammation coupled to immunological cellular actions. Clear evidence is presented that questions the automatic diagnostics of an oral implant disease based on the finding of so called mucositis that in many instances represents but a normal tissue response to foreign body implants instead of disease. Furthermore, neither is marginal bone loss around implants necessarily indicative of a disease; the challenge to the implant represented by bone resorption may be successfully counteracted by local defense mechanisms and a new tissue-implant steady state may evolve. Similar reactions including chronic inflammation occur in the interface of orthopedic implants that display similarly good long-term results as do oral implants, if mainly evaluated based on revision surgery in orthopedic cases. The most common mode of failure of orthopedic implants is aseptic loosening which has been found coupled to a reactivation of the inflammatory- immune system. Conclusions: Implants survive in the body due to balanced defense reactions in form of chronic inflammation and activation of the innate immune system. Ten year results of oral and hip /knee implants are hence in the 90+ percentage region. Clinical problems may occur with bone resorption that in most cases is successfully counterbalanced by the defense/healing systems. However, in certain instances implant failure will ensue characterized by bacterial attacks and/or by reactivation of the immune system that now will act to remove the foreign bodies from the tissues.
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| 9. |
- Albrektsson, Tomas, 1945, et al.
(författare)
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Osteoimmune regulation underlies oral implant osseointegration and its perturbation
- 2023
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Ingår i: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- In the field of biomaterials, an endosseous implant is now recognized as an osteoimmunomodulatory but not bioinert biomaterial. Scientific advances in bone cell biology and in immunology have revealed a close relationship between the bone and immune systems resulting in a field of science called osteoimmunology. These discoveries have allowed for a novel interpretation of osseointegration as representing an osteoimmune reaction rather than a classic bone healing response, in which the activation state of macrophages ((M1-M2 polarization) appears to play a critical role. Through this viewpoint, the immune system is responsible for isolating the implant biomaterial foreign body by forming bone around the oral implant effectively shielding off the implant from the host bone system, i.e. osseointegration becomes a continuous and dynamic host defense reaction. At the same time, this has led to the proposal of a new model of osseointegration, the foreign body equilibrium (FBE). In addition, as an oral wound, the soft tissues are involved with all their innate immune characteristics. When implant integration is viewed as an osteoimmune reaction, this has implications for how marginal bone is regulated. For example, while bacteria are constitutive components of the soft tissue sulcus, if the inflammatory front and immune reaction is at some distance from the marginal bone, an equilibrium is established. If however, this inflammation approaches the marginal bone, an immune osteoclastic reaction occurs and marginal bone is removed. A number of clinical scenarios can be envisioned whereby the osteoimmune equilibrium is disturbed and marginal bone loss occurs, such as complications of aseptic nature and the synergistic activation of pro-inflammatory pathways (implant/wear debris, DAMPs, and PAMPs). Understanding that an implant is a foreign body and that the host reacts osteoimmunologically to shield off the implant allows for a distinction to be drawn between osteoimmunological conditions and peri-implant bone loss. This review will examine dental implant placement as an osteoimmune reaction and its implications for marginal bone loss.
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| 10. |
- Andersson, Therese, et al.
(författare)
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Surface immobilized zoledronate improves screw fixation in rat bone: A new method for the coating of metal implants
- 2010
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Ingår i: JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE. - : Springer Science Business Media. - 0957-4530 .- 1573-4838. ; 21:11, s. 3029-3037
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies show that surface immobilized bisphosphonates improve the fixation of stainless steel screws in rat tibia after 2-8 weeks of implantation. We report here about the immobilization of a potent bisphosphonate, zoledronate, to crosslinked fibrinogen by the use of another technique, i.e. ethyl-dimethyl-aminopropylcarbodiimide (EDC)/imidazole immobilization. Bone fixation of zoledronate-coated screws was compared to screws coated with crosslinked fibrinogen only and ditto with EDC/N-hydroxy-succinimide immobilized pamidronate. Fixation in rat tibia was evaluated by a pull-out test at either 2 or 6 weeks after implantation. Both bisphosphonate coatings increased the pull-out force at both time points, and zoledronate showed a significantly higher pull-out force than pamidronate. To further evaluate the new coating technique we also performed a morphometric study, focusing on the area surrounding the implant. The zoledronate coating resulted in an increased bone density around the screws compared to controls. No pronounced increase was seen around the pamidronate coated screws. Together, the results demonstrate the possibility of obtaining a significant local therapeutic effect with minute amounts of surface immobilized zoledronate.
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