| 1. |
- Jemt, Torsten, 1950, et al.
(författare)
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Accuracy of implant-supported prostheses in the edentulous jaw: analysis of precision of fit between cast gold-alloy frameworks and master casts by means of a three-dimensional photogrammetric technique.
- 1995
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Ingår i: Clinical Oral Implants Research. - : Wiley. - 0905-7161 .- 1600-0501. ; 6:3, s. 172-80
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Tidskriftsartikel (refereegranskat)abstract
- Distortions of 15 routine implant-supported prostheses were measured in relation to the master casts after completion by means of a 3-dimensional (3-D) photogrammetric technique. All prostheses were designed as one-piece gold-alloy castings with resin teeth. Five of the prostheses were placed in the edentulous maxilla, and the remaining were placed in the lower jaw. Distortion of the cylinders was mostly observed in the horizontal plane (x- and y-axis) while the vertical aspect seemed to be more stable. The mean 3-D center point distortion was 42 (SD 15) and 74 (SD 38) microns for the upper and lower jaws, respectively. The measurements revealed a range of 3-D center point distortion from 16 to 80 and 15 to 165 microns for the different jaws, respectively. The corresponding 3-D mean angular distortion of the cylinders was 51 (SD 35) microns in lower and 70 (SD 75) microns in the upper jaws. A correlation was found between 3-D center point distortion and the width as well as the curvature of the implant arch, indicating more displacement the wider and the more curved the arch was. The 3-D center point distortion was also significantly higher in the upper jaws which could possibly be explained by the curvature of the implant arch and higher numbers of implants in the upper jaws. Further problems with the fit of upper jaw castings could be related to more alloy in the castings and poor alignment of implants.
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| 2. |
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| 3. |
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| 4. |
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| 5. |
- Lindh, T, et al.
(författare)
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A meta-analysis of implants in partial edentulism.
- 1998
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Ingår i: Clinical Oral Implants Research. - 0905-7161 .- 1600-0501. ; 9:2, s. 80-90
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Tidskriftsartikel (refereegranskat)abstract
- A meta-analytic technique was used to estimate the survival of implants supporting bridges or single crowns in partially edentulous patients. A survey of the literature revealed 66 studies, published between 1986 and 1996. Nine studies on single implants and 10 studies on fixed partial dentures met the inclusion criteria for the meta-analysis. Data from a total of 2686 implants, 570 single crowns (SC) and 2116 in fixed partial dentures (FPD), were analyzed. In order to calculate annual survival rates for individual studies a life-table analysis was conducted. Maximum follow-up time ranged between 1 and 8 years. After 1 year the success rate was calculated to be at least 85.7% for FPD and 97.2% for SC. When the results from the FPD studies were pooled the survival rate was 93.6% after 6-7 years. The corresponding value for SC was 97.5%.
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| 6. |
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| 7. |
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| 8. |
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| 9. |
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| 10. |
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| 11. |
- Dahlin, Christer, 1959, et al.
(författare)
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Histological morphology of the e-PTFE/tissue interface in humans subjected to guided bone regeneration in conjunction with oral implant treatment.
- 1998
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Ingår i: Clinical oral implants research. - : Wiley. - 0905-7161. ; 9:2, s. 100-6
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the present investigation was to study the histological morphology of the e-PTFE membrane/tissue interface in 5 humans subjected to GBR treatment in conjunction with oral implant treatment. Oral implants (Brånemark System) were inserted in extraction sockets 1 to 2 months after extraction of periodontally diseased teeth. The implants were placed approximately 2 mm below the surrounding bone margins. Specially designed 3 mm high cover-screws with horizontal slits for tissue ingrowth were applied to the implants and covered with e-PTFE membranes (GoreTex Augmentation Material). Re-entry was made 7 months later, except in 1 case where the membrane was removed 1 month postoperatively due to exposure and infection. In the remaining 4 sites, circular biopsies comprising membranes, tissues and cover-screws were retrieved. The specimens were fixated, processed and sectioned for light- and transmission electron microscopy. The space between the membrane and the cover-screw was occupied by fibrous tissue and varying amounts of bone. A cell- and vessel-rich fibrous tissue separated the bone from the membrane in the majority of the specimens. The membrane itself was penetrated by fibrous tissue. Fibroblasts and macrophages were the main cell types found in the fibrous tissue. The presence of irregularly shaped cells and unevenly distributed collagen fibres, indicated that the absence of bone formation may be due either to micromovements in the e-PTFE/tissue interface or to formation of fibrous tissue underneath the membrane by penetrating fibroblasts or a combination of these 2 phenomena.
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| 12. |
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| 13. |
- Esposito, Marco, 1965, et al.
(författare)
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Immunohistochemistry of soft tissues surrounding late failures of Brånemark implants.
- 1997
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Ingår i: Clinical oral implants research. - 0905-7161. ; 8:5, s. 352-66
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Tidskriftsartikel (refereegranskat)abstract
- The objective of the present investigation was to characterize the cellular composition of the soft tissues surrounding consecutively retrieved late failures of Brånemark implants. Criteria for implant failure were signs of loss of osseointegration (radiographic peri-fixtural radiolucency and mobility). The clinical history of the implants did not include adverse symptoms. At the time of retrieval, percussion-induced pain was experienced at 4/8 implants, but no macroscopical signs of inflammation or infection or infection was observed. Immunohistochemistry was applied on 6 marginal peri-implant specimens and on specimens of deeper tissues associated with the previously load-bearing implant surface from 8 failed implants, whereas 6 clinically healthy mucosal specimens and 4 hyperplastic biopsies from stable implants served as controls. The immunohistochemical evaluation showed that the soft tissues surrounding failed implants contained a large number of macrophages (CD68), HLA-DR positive cells, lymphocytes and plasma cells preferentially accumulated towards the removed implant surface. PMNs were a rare finding. Downgrowth of epithelium, in some cases encapsulating the whole fixture, was observed in sections where an intact implant/soft tissue interface was preserved. Healthy control mucosal specimens always contained labelled cells, albeit in a low amount, whereas hyperplastic control samples displayed an intense inflammatory and immunological response with numerous positive cells and PMNs scattered throughout the biopsy. In conclusion, failed implants were characterized by a chronic inflammatory response of the surrounding tissues with macrophages as the predominant labelled cell type, while hyperplastic tissues around stable implants were distinguished by an acute inflammatory process. These findings suggest that an on-going infection is unlikely to be the etiological factor for the late failures of dental implants examined in this study.
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| 14. |
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| 15. |
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| 16. |
- Friberg, Bertil, 1950, et al.
(författare)
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Evaluation of bone density using cutting resistance measurements and microradiography: an in vitro study in pig ribs.
- 1995
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Ingår i: Clinical oral implants research. - 0905-7161. ; 6:3, s. 164-71
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Tidskriftsartikel (refereegranskat)abstract
- A method using cutting resistance measurements during low-speed threading for identification of various bone densities has been evaluated with regard to its precision and potential. Pig ribs were used as test samples. Differing hand pressure, minor deviation (5 degrees) from a vertical tapping direction and individual threading did not reveal any significant differences in cutting resistance values. After implants were inserted into the threaded canals, the total bone as well as trabecular and compact bone areas surrounding the implants were calculated via a computer program and using microradiographs of the bone test samples. The outcome of the cutting resistance measurements was compared with that of the microradiographic technique, and good agreement was observed between the two procedures in the ability to identify bone density. Therefore, cutting resistance measurements may in the future also be used to clinically identify bone qualities in jaws.
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| 17. |
- Friberg, Bertil, 1950, et al.
(författare)
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Identification of bone quality in conjunction with insertion of titanium implants. A pilot study in jaw autopsy specimens.
- 1995
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Ingår i: Clinical oral implants research. - 0905-7161. ; 6:4, s. 213-9
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Tidskriftsartikel (refereegranskat)abstract
- Ten autopsy jaw specimens (6 mandibles, 4 maxillae) were used for cutting resistance measurements during low-speed threading. Overall, 31 sites were analyzed where implants were inserted into threaded canals. Bone area measurements were performed around the implants as described previously. The cutting resistance values together with the total bone area values were found to be higher in mandibles than in maxillae, and a tendency towards higher values was seen in incisor regions compared with premolar regions. Furthermore, an intraindividual comparison between the true cutting resistance and the bone density values of prepared sites showed a statistically significant correlation. The method with cutting resistance measurements for evaluation of bone quality seems therefore to be reliable, at least when used in human autopsy jaw bone specimens.
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| 18. |
- Friberg, Bertil, 1950, et al.
(författare)
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Mk II: the self-tapping Brånemark implant: 5-year results of a prospective 3-center study.
- 1997
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Ingår i: Clinical oral implants research. - 0905-7161. ; 8:4, s. 279-85
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Tidskriftsartikel (refereegranskat)abstract
- The 5-year result of a prospective 3-center study is presented, comprising 103 patients with 288 Mk II self-tapping and 275 standard implants of the Brånemark System. Out of 363 mandibular and 200 maxillary fixtures, one Mk II was lost of the lower jaw and 13 of each implant type failed in maxillae during the study period. Cumulative prosthesis stability was 97%. Five patients accounted for more than 85% of the fixture losses. Marginal bone resorption was similar for both implant designs. Apart from the implant failures and one patient exhibiting disturbed nerve sensation of the mental nerve, no major complications were encountered. Overall, this study revealed equal cumulative success rates for standard and Mk II implants after 5 years of observation. Mandibular implants exhibited greater success rates (100%) for both tested implant types compared to maxillary implants (87%).
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| 19. |
- Ivanoff, Carl-Johan, et al.
(författare)
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Influence of initial implant mobility on the integration of titanium implants. An experimental study in rabbits.
- 1996
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Ingår i: Clinical oral implants research. - 0905-7161. ; 7:2, s. 120-7
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, the influence of initial instability on the healing of titanium implants was studied in 9 lop-eared rabbits. Titanium implants (Brånemark System) were inserted in the tibiae, a location with cortical bone only, in such a way that they were either stable (control), rotation-mobile, or totally mobile. Implants were also inserted in the distal femoral condyles, representing an implantation bed with mainly cancellous bone, so they either showed no initial mobility (control) or were rotation-mobile. After 12 weeks of healing, the implants were retrieved, together with surrounding bone, fixed, dehydrated, and embedded in plastic resin. About 10 micron thick ground sections were prepared for light microscopic morphometry. The mineralized bone to titanium contact, and the amount of bone occupying the threads, were calculated, whereafter the outcome of the different locations were compared. All retrieved implants were clinically stable at the of the experiment. For the tibia sites, a statistically significant less bone to titanium contact, and a less amount of bone in the threads, were found for the totally mobile implants, as compared to the corresponding initially stable controls. Moreover, a statistically significant higher amount of bone was found in the threads of the rotation-mobile implants inserted in the femoral condyle as compared to their initially stable controls. The study indicated that initial rotation-mobility, independent if it occurs in cortical or trabecular bone, does not necessarily lead to an inferior integration of unloaded implants. However, initial total implant mobility within the cortical layer results in a statistically significant less amount of bone around the implants, as compared to stable controls.
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| 20. |
- Ivanoff, Carl-Johan, et al.
(författare)
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Influence of soft tissue contamination on the integration of titanium implants. An experimental study in rabbits.
- 1996
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Ingår i: Clinical oral implants research. - 0905-7161. ; 7:2, s. 128-32
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, the influence of peroperative soft tissue contamination on the healing of titanium implants was studied in 9 lop-eared rabbits. Titanium implants (Brånemark System) were inserted in the tibiae, a location with cortical bone only, in such a way that one group was inserted the standard way (control), and another group was contaminated for 30 s in the adjacent soft tissues, prior to insertion. The implants were allowed to heal for 12 weeks and were then retrieved together with surrounding bone, fixed, dehydrated and embedded in plastic resin. About 10 micron thick ground sections were prepared for light microscopic morphometry. The mineralized bone-to-titanium contact, and the amount of bone occupying the threads, were calculated for each implant, and the results of the two groups were compared. All retrieved implants were clinically stable at the end of the experiment. Regarding bone-to-titanium contact and bone area within the threads, a statistically nonsignificant difference was observed between the 2 groups. This study indicated that peroperative soft tissue contamination of c.p. titanium implants does not prevent osseointegration from occurring, when studied in the rabbit tibia.
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| 21. |
- Jemt, Torsten, 1950, et al.
(författare)
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Measurements of bone and frame-work deformations induced by misfit of implant superstructures. A pilot study in rabbits.
- 1998
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Ingår i: Clinical oral implants research. - : Wiley. - 0905-7161. ; 9:4, s. 272-80
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Tidskriftsartikel (refereegranskat)abstract
- This in vivo study used a 3-D photogrammetric technique to measure distortion of 3 unit implant frame-works and bone surrounding osseointegrated implants after securing misfitting superstructures to the implants. Four adult loop-eared rabbits were provided with 3 implants each in the proximal part of 1 tibia each. After a healing period of 8 weeks, a titanium frame-work was connected with a misfit to the central implant. Three-dimensional photographs were taken before and after securing the central screw, which induced a calculated mean preload of 246 N. Measurements and comparisons of the topography of the frame-works and surrounding bone before and after tightening the central screw indicated a complex and inconsistent deformation pattern. Generally, it could be observed that the top edge of the central cylinder showed vertical movement towards the bone of about 150 microns, always in combination with a rotation of the entire super-structure. The head of the central implant seemed to show a corresponding displacement towards the frame-work of about 50 to 200 microns. Bone deformation was found to be basically localized between the implants, where compressions of about half a millimetre were observed. This concentration of bone deformation as a result of misfit may be one contributing factor to initial marginal bone loss, occasionally observed after insertion of implant supported prostheses.
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| 22. |
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| 23. |
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| 24. |
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| 25. |
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| 26. |
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| 27. |
- Lindquist, Lars W, et al.
(författare)
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A prospective 15-year follow-up study of mandibular fixed prostheses supported by osseointegrated implants. Clinical results and marginal bone loss.
- 1996
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Ingår i: Clinical oral implants research. - 0905-7161. ; 7:4, s. 329-36
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Tidskriftsartikel (refereegranskat)abstract
- In this prospective study 47 edentulous patients were treated with mandibular fixed prostheses supported by osseointegrated Brånemark implants and followed for 12 to 15 years. Three (1%) of the 273 inserted implants were lost, two before and one six years after placement of the fixed prosthesis. The cumulative success rate (CSR) of the implants was 98.9% both after 10 and 15 years. None of the fixed prostheses was lost and at the last follow-up, all patients had stable fixed prostheses in function (CSR 100%). The marginal bone loss around the implants was small, on average 0.5 mm during the first post surgical year and thereafter about 0.05 mm annually. More bone was lost around the anterior implants than around the most posterior ones. Smoking and poor oral hygiene had significant influence on bone loss, while occlusal loading factors such as maximal bite force, tooth clenching and length of cantilevers were of minor importance. It is concluded that the long-term results of the mandibular implant treatment were extremely successful, regarding both the fixed prostheses and implant stability. Bone resorption around the implants, albeit limited, was influenced by several factors, smoking and oral hygiene appeared to be most important.
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| 28. |
- Lundgren, Anna Karin, et al.
(författare)
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Augmentation of skull bone using a bioresorbable barrier supported by autologous bone grafts. An intra-individual study in the rabbit.
- 1997
-
Ingår i: Clinical oral implants research. - : Wiley. - 0905-7161. ; 8:2, s. 90-5
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this experimental investigation was to compare the effect of using autologous particulate bone grafts with and without a bioresorbable barrier covering for augmentation of the rabbit skull bone. For this purpose, bilateral, circular, 8 mm wide and 1 mm deep skull bone defects were prepared and overfilled with particulate bone grafts. The grafts placed in the test sites were covered with a bioresorbable barrier (Guidor Matrix Barrier). The grafts placed in the control sites were covered only by the repositioned, cutaneous flap. 12 weeks later, the animals were sacrificed, the experimental sites were defleshed and the height and volume of the augmented bone in the test and control sites were measured clinically. Histologically, morphometrical measurements of the bone tissue were performed in decalcified vertical cross-sections of the experimental sites. Statistically significant differences were found in favour of the coverage of the bone graft particles with the barrier, both with respect to the height and the volume of the augmented bone.
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| 29. |
- Lundgren, Anna Karin, et al.
(författare)
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Bone augmentation at titanium implants using autologous bone grafts and a bioresorbable barrier. An experimental study in the rabbit tibia.
- 1997
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Ingår i: Clinical oral implants research. - : Wiley. - 0905-7161. ; 8:2, s. 82-9
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of the present investigation was to compare the effect of using autologous bone particles covered with a bioresorbable matrix barrier with the use of bone particles alone on bone augmentation at titanium implants installed in the rabbit tibia. Two Brånemark System implants, one in each tibia, were inserted in each of 9 rabbits in such a way that 5 threads were not covered with bone. Autologous bone particles were harvested from the skull and placed over the exposed implant surfaces on each tibia. The bone graft on one tibia was covered with a Guidor Matrix Barrier, while the bone graft on the other tibia served as a control. After a healing period of 12 weeks, the animals were sacrificed and specimens taken for histomorphometrical analyses. The analyses showed that a significantly larger volume of augmented bone tissue had formed at the test sites. There were, however, no differences in the amount of mineralized bone. In fact, the difference in tissue volume was due to an increased amount of bone marrow at the test sites. The degree of mineralized bone to implant contact as well as the degree of mineralized bone within the threads at the test implants were similar to that at the controls. In conclusion, it was found that the coverage of particulate autologous bone grafts with a bioresorbable barrier resulted in a larger volume of augmented bone than the use of bone grafts not covered with a barrier.
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| 30. |
- Lundgren, Dan, et al.
(författare)
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Augmentation of intramembraneous bone beyond the skeletal envelope using an occlusive titanium barrier. An experimental study in the rabbit.
- 1995
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Ingår i: Clinical oral implants research. - : Wiley. - 0905-7161. ; 6:2, s. 67-72
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this investigation was to evaluate whether augmentation of intramembraneous bone beyond the skeletal envelope can be predictably achieved by placing a completely occlusive barrier on the skull bone of rabbits, hereby creating a secluded space with bone tissue being the only adjoining tissue. The experiment was carried out in 3 New Zealand white rabbits. In each animal, a midline incision was made down to the bone surface of the skull and a skin-periosteal flap was raised to expose the skull bone on both sides of the midline. Two prefabricated titanium domes with an inner diameter of 4.5 mm and an inner height of 3.0 mm were installed on each side. The domes were supplied with a horizontal, peripheral flange and a vertical edge, fitting tightly into a circular slit, prepared by a trephine into the skull bone. This arrangement ensured a stable anchorage of the dome and a reliable peripheral sealing of the space. The skin-periosteal flaps were relocated to cover the domes and sutured. After a healing period of 3 months, the animals were killed and the experimental areas excised and prepared for histological transversal ground sections with each dome in situ. The results demonstrated complete bone fill of all domes, with no signs of ingrowth of other types of tissues, indicating that the use of a barrier with total occlusiveness, sufficient stiffness and stability and reliable peripheral sealing will result in predictable bone augmentation of spaces also beyond the skeletal envelope.
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| 31. |
- Lundgren, Dan, et al.
(författare)
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The effect of mechanical intervention on jaw bone density.
- 1995
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Ingår i: Clinical oral implants research. - : Wiley. - 0905-7161. ; 6:1, s. 54-9
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this investigation was to test the hypothesis that jaw bone, subjected to mechanical intervention, will heal with increased density compared with conditions before the traumatic insult. The natural edentulous area between the incisor and the first molar on both sides of the maxillary jaw of 8 adult New Zealand white rabbits constituted the experimental model. On the test side, holes were drilled through the cortical plate and into the cancellous bone. No drilling was performed on the contralateral control side. One transversal ground section from each specimen, taken in the centre of and representing both the test and control site, was prepared to ensure that the same sagittal level of the jaw was represented. Morphometric measurements were performed and comprised assessments of the total cross-sectional area of 1) the edentulous part of the jaw, 2) the cortical bone plates and 3) the bone trabeculae and marrow spaces of the cancellous bone. The mechanical intervention resulted in a substantial alteration of the bone tissue morphology, the most conspicuous change being a markedly increased number of bone trabeculae per cancellous bone unit. Thus, the area occupied by bone trabeculae was about twice as large in the test sites compared with the control sites (+103%), whereas the area occupied by bone marrow cavities and cortical bone was significantly smaller. The clinical implications of the findings for potential treatment of fragile bone tissues and bone sites intended for implant insertion are discussed.
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| 32. |
- Meredith, N, et al.
(författare)
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Resonance frequency measurements of implant stability in vivo. A cross-sectional and longitudinal study of resonance frequency measurements on implants in the edentulous and partially dentate maxilla.
- 1997
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Ingår i: Clinical oral implants research. - 0905-7161. ; 8:3, s. 226-33
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this investigation was to evaluate the use of resonance frequency measurements in the clinical measurement of implant stability. Resonance frequency measurements are undertaken by measuring the response of a small transducer attached to an implant fixture or abutment. Two groups of patients were selected for study. Group A comprised 9 patients who had a total of 56 implants placed. Resonance frequency measurements were made at fixture installation and repeated 8 months later at abutment connection. The resonance frequency of the implant/transducer system increased for 50 out of the 56 implants from a mean value of 7473 Hz +/- 127 Hz (P < 0.05) to a mean of 7915 Hz +/- 112 Hz (P < 0.05). Two implants had failed to integrate and the resonance frequency of these had fallen. Group B comprised 9 patients who had been provided with fixed prostheses and had a total of 52 implants placed. They were examined 5 years after fixture placement and the prostheses removed. All implants were judged clinically to be osseointegrated. The level of the marginal bone around each implant was calculated by measuring the number of exposed threads on intraoral periapical radiographs and added to the length of each abutment to give a value termed the effective implant length (EIL). Measurements indicated a correlation (R = -0.78, P < 0.01) between EIL and resonance frequency. The results support the hypothesis that the resonance frequency of an implant/transducer system is related to the height of the implant not surrounded by bone and the stability of the implant/tissue interface as determined by the absence of clinical mobility.
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| 33. |
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| 34. |
- Mouhyi, J, et al.
(författare)
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Temperature increases during surface decontamination of titanium implants using CO2 laser.
- 1999
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Ingår i: Clinical oral implants research. - : Wiley. - 0905-7161. ; 10:1, s. 54-61
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the present in vitro investigation was to measure temperature changes at the implant surface when using pulsed CO2 laser in a simulated implant surface decontamination protocol. Six threaded titanium implants were placed in a fresh resected pig mandible. A 4 x 4 mm defect was created buccally to each implant in order to expose the implant head and approximately 5 threads. Temperature changes were monitored by two thermocouples placed near the dehiscence and at the apical part of the implant. Several setting combinations of the CO2 laser with regard to output power, pulse width, pulse repetition rate and irradiation time were tested on dry and wet (distilled water) surfaces. Only minor temperature increases were measured when lasing wet titanium surfaces, while the temperature at dry surfaces exceeded the proposed thresholds for bone damage at clinically relevant settings. It is concluded that the CO2 laser when used on a wet implant surface in a pulsed mode at 8 W/10 ms/20 hz during 5 s induces a temperature increase of less than 3 degrees C. This would minimize the risk of temperature induced tissue damage as a result of lasing implant surfaces.
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| 35. |
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| 36. |
- Rasmusson, Lars, 1962, et al.
(författare)
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Measurements of stability changes of titanium implants with exposed threads subjected to barrier membrane induced bone augmentation. An experimental study in the rabbit tibia.
- 1997
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Ingår i: Clinical oral implants research. - : Wiley. - 0905-7161. ; 8:4, s. 316-22
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the present study was to evaluate in a rabbit model the changes in stability of implants that had been subjected to barrier membrane induced bone augmentation, as compared to untreated controls. One titanium implant was inserted in each proximal tibial metaphysis of 10 rabbits. The implants were placed in such a way that 4-5 threads on one side of the implant were left uncovered by bone. On the test side, the exposed implant surface was treated by means of a barrier membrane technique to provide for bone augmentation, while the contralateral side was untreated. The stability evaluations were made by means of resonance frequency measurements (RFM) at Day 0 and after 8, 16 and 24 weeks of healing. In addition, changes in the area of exposed implant threads were documented and measured on photographs. Removal torque measurements were performed at the day of sacrifice. In this study it was not possible to demonstrate a statistically significant better stability of implants subjected to barrier induced bone augmentation as compared to control implants still having exposed threads as evaluated by RFM and removal torque measurements.
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| 37. |
- Rasmusson, Lars, 1962, et al.
(författare)
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Morphological and dimensional changes after barrier removal in bone formed beyond the skeletal borders at titanium implants. A kinetic study in the rabbit tibia.
- 1997
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Ingår i: Clinical oral implants research. - : Wiley. - 0905-7161. ; 8:2, s. 103-16
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present experimental investigation was to study the morphological and dimensional changes of bone, augmented at titanium implants by a membrane technique, taking place after membrane removal. In 12 rabbits, screw-shaped titanium implants were inserted in the tibial metaphyses in such a way that 5 threads became uncovered with bone. Surgery was performed on 2 occasions in order to retrieve specimens with different follow-up times. An e-PTFE barrier and a titanium device were used to provide space for bone formation. In 1 tibia of each rabbit, the membranes and spacers were removed after 8 weeks of healing, and the implants followed for 16 more weeks. Impressions were taken at day 0 and after 8 and 24 weeks of healing and plaster models were produced. In the contralateral tibiae, implants were inserted either 16 or 8 weeks prior to sacrifice. Measurements were made on the plaster models in 3 dimensions at 35 points around each implant in a coordinate measuring machine. Specimens taken 8, 16 and 24 weeks after insertion were analysed by means of light microscopical morphometry. The coordinate measurements showed that, in mean, 1.92 mm of bone had been formed during the first 8 weeks. A statistically significant loss of the height of the newly formed bone (0.70 mm) and thereby reduction of bone volume was found 24 weeks postoperatively. The volume decrease of the newly formed bone was more pronounced beside the implants than over the implant body. The histology showed that woven bone had been formed at the implants after 8 weeks. Further bone formation and remodelling and a net increase of mineralized bone were seen. The degree of bone-implant contact and bone area in the threads increased with time. The present study showed that coordinate measurements on plaster models, obtained from the experimental areas, in combination with histology, form a useful technique to study long-term changes of augmented bone. It was found that bone formed by a barrier membrane technique, decreased in volume during a 16-week follow-up period after barrier removal. Less dimensional changes were observed for the bone formed over the implant body, indicating that a solid surface may have a stabilizing effect on the augmented bone.
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| 38. |
- Shagaldi, F, et al.
(författare)
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The application of resonance frequency measurements to study the stability of titanium implants during healing in the rabbit tibia.
- 1997
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Ingår i: Clinical oral implants research. - : Wiley. - 0905-7161. ; 8:3, s. 234-43
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this investigation was to measure the resonance frequency of a number of implants placed in the rabbit tibia at insertion and at predetermined periods thereafter and to correlate the results with histomorphometric measurements made when the animals were sacrificed. Ten mature New Zealand White rabbits were used in the study. Two c.p. threaded titanium implants were placed in the right tibia of each animal. Resonance frequency measurements were made by screwing a small transducer onto a standard abutment mounted on each fixture. Measurements were repeated with the transducer oriented perpendicular and parallel to the long axis of the tibia for all proximal implants 14 and 28 days after placement and in 6 implants additionally at 42, 56, 93, 122 and 168 days after which all animals were sacrificed. Histomorphometric analysis comprised 2 parts; measurement of bone-implant contact area and height. A significant increase in resonance frequency was observed after 14 (405 Hz, +/- 234 Hz) and 28 (658 Hz, +/- 332 Hz) days. The increase in resonance frequency levelled after approximately 40 days and little further change was observed. The variation in bone-implant contact area was relatively small (1.8-4.9 mm2) and the range of bone-implant contact heights was also narrow (-1.5 (-)+ 1.5 mm). Values for resonance frequencies plotted against contact area and height were grouped around 10 kHz. In conclusion, it was shown that resonance frequency measurements can be made at placement and during healing in vivo and changes may be related to the increase in stiffness of an implant in the surrounding tissues.
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| 39. |
- Thilander, Birgit, et al.
(författare)
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Single implants in the upper incisor region and their relationship to the adjacent teeth. An 8-year follow-up study.
- 1999
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Ingår i: Clinical oral implants research. - 0905-7161. ; 10:5, s. 346-55
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to find out if implant-supported crowns in the upper incisor region run the risk of coming into an infraoccluded position later in life. Ten adolescents with 15 implant-supported crowns were included in the study. The age of the patients at the implant surgery ranged between 14 and 19 years. They were followed up during an 8-year period. No implant loss was observed. A good or acceptable aesthetic appearance at the last observation was found in most subjects. In some of them a change in the vertical position of the implant-supported crown, resulting in infraocclusion, could be registered, especially in subjects with no incisor contact. Throughout the follow-up period, only minor loss of marginal bone support was observed at the implants. At the teeth adjacent to the implant, a reduction of the marginal bone level was observed in some patients. Of importance to consider in single implant therapy is that a fixed chronological age is no guidance for implant placement, due to a slight continuous eruption of the adjacent teeth post adolescence. An orthodontic treatment should be performed not only in order to gain space in the implant area, but also to attain good incisor stability to reduce the risk of infraocclusion of the implant-supported crown. Furthermore, 3 cases will exemplify that infraocclusion also may occur in patients who had received single implants at adult ages.
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