摘要:

This study details the structural and ultrastructural features of the interfaces between titanium implants and their surrounding tissues. The material stemmed from an experiment in dogs in which guided tissue regeneration with Gore‐Text membranes was used to treat peri‐implant, ligature‐induced tissue breakdown around submerged and nonsubmerged com‐mercially pure titanium implants. Specimens from the nonsubmerged group were evaluated under light microscopy and scanning and transmission electron microscopy. A healthy gingiva and a gingival sulcus were formed around the implant necks. A regenerated junctional epithelium provided the epithelial union between implant and gingiva. The supracrestal connective tissue was characterized by a 3‐dimensional network of collagen fibers, fibroblasts and blood vessels. Near the implant surface the collagen fibers ran parallel to the titanium surface or were orientated perpendicular to the implant. The connective tissue‐implant interface was characterized by a fine fibrillar material interposed between the implant surface and the connective tissue. An unidentified material was also observed between the endings of functionally orientated collagen fibrils and the metallic surface. The apical portions of the implants were anchored in compact bone. At the bone‐implant interface, either mineralized bone matrix was intimately adapted to the titanium surface without any intervening space or a 0.5 μm wide unmineralized layer was interposed. These findings indicate that a perimucosal seal was formed around the implants consisting of a junctional epithelium‐implant union coronally and supported by the connective tissue‐implant junction apically. The implants were integrated in connective tissue, but only tight

ISSN:0905-7161    

DOI:10.1034/j.1600-0501.1994.050201.x

出版商:Munksgaard International Publishers    

年代:1994

数据来源: WILEY

摘要:

The aim of this study was to explore the possibility of obtaining bone regeneration in jaw bone defects in rats after coverage of the defects with an occlusive bioresorbable membrane. The experiment was carried out in 31 rats. The mandibular ramus was exposed in both sides and a 2 x 3 mm defect was produced at its lower border. A gutta‐percha point was placed to indicate the original level of the border. The defect on one side was covered with a polyhydroxybutyrate resorbable membrane, whereas the contralateral side received no membrane before closure of the wound. Macerated jaw specimens representing 3 and 6 months of healing demonstrated minimal bone fill in the control defects, whereas all test defects healed to or close to the gutta‐percha point, indicating the original inferior border of the jaw. The histological analysis demonstrated increasing bone fill in the test specimens from 15–180 days, whereas only 35–40% of the defect area in the control sides was filled with bone after 3–6 months. Ingrowth of muscular. glandular and connective tissue was consistently occurring in the control defects during healing. It can be concluded that selective repopulation of bone defects with bone‐forming cells can be ensured by excluding surrounding soft tissues from the wound area with an occlusive bioresorbab

ISSN:0905-7161    

DOI:10.1034/j.1600-0501.1994.050202.x

出版商:Munksgaard International Publishers    

年代:1994

数据来源: WILEY

摘要:

The aim of the present study was to investigate whether it is possible to increase the height of the rat mandible at its inferior border using a bioresorbable membrane adapted to create a secluded space for ingrowth of bone tissue. The experiment was carried out in 18 rats. The mandibular ramus was exposed at both sides. A standardized titanium microimplant was then inserted in the naturally existing curvature at the inferior border of the mandible, serving as a fixed reference and space maker. The mandibular border on one side was covered with a polyhydroxybutyrate bioresorbable membrane, and the contralateral side, serving as control, received no membrane before closure of the wound. The membranes were placed in such a way that a space was created in the curvature between the membrane and the inferior border of the mandible. Macerated jaw specimens representing 6 months of healing demonstrated substantial amounts of bone formation in the curvature of the inferior border of the mandible, resulting in a flattening of the inferior border. Negligible amounts of bone formation had occurred in the control sides. Histological analysis demonstrated that. in 4 of 6 experimental specimens, the space created by the membrane was completely filled with new bone after 6 months of healing, but in some specimens soft tissue seemed to have migrated into the space through ruptures of the membrane or because of poor membrane adaptation at its lateral borders, thereby inhibiting bone formation. Only negligible bone formation had occurred at the control sides. It can be concluded that augmentation of the mandible can be accomplished using a bioresorbable membrane of polyhydroxybutyrate adapted to create a secluded space for ingrowth of bone tissue. but the membrane must be modified regarding its physical properties before clinical use in maxillofacial surgery.

ISSN:0905-7161    

DOI:10.1034/j.1600-0501.1994.050203.x

出版商:Munksgaard International Publishers    

年代:1994

数据来源: WILEY

摘要:

The purpose of this study was to evaluate the use of a biodegradable membrane of polyhydroxybutyrate‐hydroxyvalerate copolymer reinforced with polyglactin 910 fibers, as an occlusive barrier over implants placed into fresh extraction sockets. Ten dogs had the 3rd and 4th mandibular premolars extracted bilaterally. Each dog had 4 Astra Dental Implants® placed directly into the fresh extraction sockets. The top of the fixtures was placed at the same level as the top of the buccal cortical bone. The two implants in the right side were covered with the hydrolyzable polyester material (polyhydroxybutyrate‐hydroxyvalerate reinforced with polyglactin 910 fibers; PHB‐HVIPG). and the 2 implants in the left side were controls without occlusive membranes. Soft tissue dehiscences were registered for half of the implants in the test side but were not noted in the control side. The histomorphological measurements after 12 weeks showed that the mean distance from the top of the fixtures to the first bone‐to‐implant contact was significantly greater than for the control side. The membrane‐covered implants without dehiscences showed also significantly less bone fill compared with the control side. Inflammatory cell infiltrates were seen adjacent to all PHB‐HVIPG membranes, and frequently the membrane material was surrounded by a fibrous tissue capsule. The polyester membranes used in this study interfered with the marginal bone healing adjacent to the immediately placed implants. An increased inflammatory reaction and significantly less marginal bone healing was registered in the membrane side compared with th

ISSN:0905-7161    

DOI:10.1034/j.1600-0501.1994.050204.x

出版商:Munksgaard International Publishers    

年代:1994

数据来源: WILEY

摘要:

The principle of guided tissue regeneration has been successfully applied for the regeneration of bone in various jaw defects in human. The purpose of this study was to assess the bone volume regenerated using nonresorbable membrane barriers. Nineteen patients with jaw bone defects of various sizes and configurations were included in the study. Combined split‐thickness/full‐thickness mucosal flaps were elevated in the area of missing bone. The size of the defects was assessed by measuring the distance from a reference line between 2 adjacent teeth (cementoenamel junctions) to the alveolar crest (a) every 2 or 3 mm. In addition, the crestal width was measured. Consequently, the surface of the triangle formed by a and the width of the crest as well as the volume between all triangles were calculated geometrically. Following the placement of Gore‐Tex® augmentation material as a barrier, the distance (b) to the top of the membrane from the reference line was assessed, and the maximum possible volume for bone regeneration based on (a‐b) and the width of the crest was calculated. At the time of membrane removal (3–8 months later). the same measurements were performed and the percentages of regenerated bone in relation to the possible volume for regeneration determined. In 6 patients in whom the membranes had to be removed early due to an increased risk for infection between 3 and 5 months, bone regeneration varied between 0 and 60%. In 13 patients in whom membranes were left for 6–8 months, regenerated bone filled 90–100% of the possible volume. It was concluded that successful bone regeneration consistently occurred with an undisturbed healing period of at

ISSN:0905-7161    

DOI:10.1034/j.1600-0501.1994.050205.x

出版商:Munksgaard International Publishers    

年代:1994

数据来源: WILEY

摘要:

Bone augmentation around implant fixtures using the technique of guided tissue regeneration has been described in a number of reports. The aim of this study was to evaluate bone fill around dehiscence defects at matched defects randomly allocated to test (expanded polytetrafluoroethylene; Gore‐Tex) or control treatments within the same patient. Six edentulous subjects were treated with overdentures supported by 2 fixtures ad modum Brinemark. In addition, 2 experimental 7 mm fixtures with nearly identical dehiscence defects on the labial aspect were placed in the anterior part of the mandible. Baseline defect heights ranged from 2.5 to 4.0 mm with 2 to 4 threads exposed. The test fixture dehiscence was covered with a Gore‐Tex membrane secured with a cover screw. The experimental fixtures were exposed after 5 months at stage 2 surgery and measurements and photographs repeated. The fixtures were then removed with a trephine and processed for histological evaluation. Regeneration of a hard tissue resembling bone was observed in 4 of 6 cases treated with Gore‐Tex, amounting to between 95 and 100% elimination of the dehiscence and total coverage of the threads. However, in one of these cases, histological evaluation showed that it was soft tissue and not bone, and in a further case soft tissue regeneration was apparent both clinically and histologically. In another case there was no significant regeneration at either test or control defects. Although there was a trend for the Gore‐Tex treated dehiscences to respond more favourably, the differences in clinical and histological measurements between test and control failed to reach statistical signi

ISSN:0905-7161    

DOI:10.1034/j.1600-0501.1994.050206.x

出版商:Munksgaard International Publishers    

年代:1994

数据来源: WILEY

摘要:

The aim of this study was to evaluate the ability of computer‐assisted densitometric image analysis (CADIA) to detect small changes in mineralized and nonmineralized tissues adjacent to dental implants and to correlate these changes with CADIA values. A section of a pig mandible including all soft tissues and in which a hollow cylinder ITI Bonefit® implant with an artificial mesial and a buccal infrabony defect was placed was used to obtain pairs of standardized radiographs. Series of radiographs were obtained with exposure times of 0.13. 0.20, 0.44. and 0.53 s. Specimens of mineralized or nonmineralized tissues were placed arbitrarily in the defects before each radiographic exposure. The radio‐graphs were captured through a video camera, digitized and stored in a personal computer. Every radiographic image was then subtracted from a baseline one without any change. The result of the subtraction was evaluated with CADIA. A linear correlation (r2=0.99) was found between the bone chips (1–5 mg of dry weight) placed in the mesial defect and the CADIA values. Bone chips in the buccal defect (behind the implant), however, were not detected unless their weight reached 14 mg or more. For conventionally exposed radiographs, it was not possible to recognize soft tissue specimens (1–6 mg), either in the buccal or the mesial defect. However, when “underexposed” radiographs (exposure time: 0.13 s) were obtained, a linear correlation (r2=0.80) was calculated for soft tissue specimens in the mesial defect and CADIA values. In normally exposed radiographs. the CADIA system could detect even the smallest change in bone density (bone chip of 1 mg of dry bone weight) and correlated almost linearly with these changes. Provided that the radiographic images are obtained with standardized geometry and normal exposure time. the tissue density changes detected by this system within bone defects represent only mineralized tissue changes. By underexposing radiographs, CADIA may even reveal soft tissue changes around den

ISSN:0905-7161    

DOI:10.1034/j.1600-0501.1994.050207.x

出版商:Munksgaard International Publishers    

年代:1994

数据来源: WILEY