 Astra Tech
BioManagement Complex
|
 Connective Contour
Connective Contour" is the unique and scientifically documented contour that increases soft tissue contact zone and volume, created when the abutment is connected to the implant. Connective Contour is also an original key feature of the Astra Tech Implant System™.
The summaries in this section highlight the understanding of soft tissue healing around and esthetics maintained by the Astra Tech Implant System.
 The barrier between the keratinized mucosa and the dental implant. An experimental study in the dog
Purpose: The connective tissue and junctional epithelium constitute the effective barrier between the oral environment and the peri-implant bone. The purpose of the present study was to investigate the tissue composition that forms the transmucosal passage around, and attachment to a dental implant.
Materials and Methods: 36 implants (TiOblast'" Astra Tech) were inserted in the healed ridge of 6 dog mandibles and left submerged to osseointegrate for 3 months. Abutments were then connected (uniAbutment'" 45°) and a plaque control program was initiated.
The dogs were euthanized after 6 months by intraarterial perfusion of a fixative. En bloc specimens were processed for the "fracture technique", and subsequently embedded in EPON. 3 Jim thin histological sections were stained with PAS and toluidine blue. In addition ultra thin (0.05 pm) uranyle acetate and lead citrate contrasted sections were also produced.
Light microscopic analysis was performed using a Leica DM-RBE* microscope equipped with an image-capture system (Q-500 MC®; Leica, Germany). The area analyzed was the closest peri-abutment tissue (length 200 pm x 20 pm wide) interposed between the apical border of the junctional epithelium and the bone, called zone A. Continuous with and lateral (or outer) to zone A, zone B was defined (length 200 pm x 160 pm wide).
Determination of the proportions (%) of collagen, fibroblasts, vascular structures and residual tissue (e.g.leucocytes, nerves, matrix components) were analyzed histometrically.
Electron micrographs were obtained from the ultra thin sections revealing the proportion of fibroblasts (using a point counting procedure and a 42-point lattice) in two zones, where one zone (30 pm wide, located within zone A) was innermost next to the implant-abutment surface, and the other zone (30 pm wide, located within zone B) was at a peripheral distance of 150 pm.
The null hypothesis was rejected at p<0.05, and the Student t-test for paired observations was applied.
Result: The most coronal barrier, the junctional epi-thelium, was 2 mm long and 40 pm wide. The con-nective tissue analyzed seemed to be in direct contact with the implant surface. Light microscopic evalu-ation indicated a structural difference between the innermost and lateral tissues. The innermost tissues (zone A) were characterized by an abundance of fibroblasts (28%) oriented parallel with the implant surface, and interposed by thin collagen fibers (66,47%) which originated from the periosteum of the bone crest running vertically. There was an absence of vascular structures in the inner zone.
The outer zone (B) housed more and larger collagen fibers (82,36%) running in various directions, and a substantial number of vessels (3,27%), but relatively few fibroblasts (10%) were identified. When comparing the inner and outer zones all variables evaluated were found to reach a statistically significant difference, p < 005.
Discussion and conclusion: The overall result from this study on the composition of the peri-implant connective tissue is in agreement with previously reported data in similar models. Furthermore it confirms that the periimplant tissues are structurally different from gingiva.
A previous hypothesis (from the same group of authors) has speculated that the scarlike barrier tissue composition and the paucity of cells could imply that the peri-implant tissue has a lower turnover than gingiva. In the present study however, a more detailed histological analysis was performed and the previous hypothesis could not be confirmed. To the contrary, there are reasons to assume that the high number of fibroblasts plays a role in the estab-lishment and maintenance of the mucosal barrier and that the tissue next to the implant have a high turn-over.
|
|
|
