 Astra Tech
BioManagement Complex
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 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.
 Three-year evaluation of single tooth implants restored 3 weeks after 1-stage surgery
Purpose: The aim of this 3-year prospective cohort study was to evaluate the outcome of early loading of implants placed in healed maxillary anterior alveolar ridges. Primary variables were implant success rate and prosthesis complications, and secondary variable was to determine the conditions of the peri-implant tissue.
Materials and methods: Patients who signed informed consent were included at either of the two centres involved. The recruitment and treatment of the patients were in accordance with Committees for Investigations involving human subjects and the Declaration of Helsinki. Patient inclusion and exclu-sion criteria has previously been presented in detail (Cooper et al.2001).
In total, 54 implants (TiOblast"", Astra Tech) were placed in a 1-stage procedure. Healing abutments were connected with light finger pressure. After 3 weeks a definitive abutment was selected, having the restorative margin about 1 mm below the mucosal margin. A temporary crown was cemented and checked for occlusal contacts in maximal intercus-pidal position, with limited or no excentric contacts. The placement of the temporary crown was considered the baseline in this study. Eight weeks after implant placement, definitive crown impressions were made and permanent crowns were cemented with glass ionomer cement.
Radiographic and clinical follow-up programme started and was performed at 6 months, 1 and 3 years. Plaque and distance from incisal edge to top of the papilla, and to buccal gingival zenith was mea-sured, as well as the width of the keratinized mucosa. A single independent investigator recorded peri-implant radiolucencies and marginal bone levels in relation to a reference point on the implant.
Descriptive statistics were calculated with a 95% confidence interval. The P value was calculated by Wilcoxon signed rank test.
Results: Forty-eight patients were treated with 54 implants placed in the maxillary canine, central or lateral incisor region. Three implants in 3 patients were lost before definitive crown cementation, giving a cumulative implant survival of 94.4%. Thirty-nine patients with 43 implants attended the 3-year follow-up. No abutment screw loosening or fracture occurred, and prosthetic complications included minor incisal porcelain fracture of 3 crowns, loosening of 2 temporary cemented crowns and 2 episodes of soft tissue character. Clinical evaluation showed low levels of plaque accumulation and only 4% of all sites showed peri-implant mucosal redness, at the 3 year control. The parameters evaluating changes in soft tissue health all showed improved results over time. Papilla size positively changed from permanent crown placement through out the study (0.53 mm at 6 m to 0.74 mm at 3 years) and the result was not an effect of the distance between the adjacent tooth and the implant (P>0.50, Kruskal-Wallis test). The distance from the incisal edge to the gingival zenith was reduced, indicating a growth of soft tissue at 1 and 3 years (0.34 ±0.94 mm and 0.51±1.42 mm, respectively). The marginal bone levels indicated initial changes from baseline to placement of the definitive crown (0.47 ±0.44 mm, p< 0.001) but no further statistically significant changes were recorded during the 1 and 3-year examinations (mean change from baseline to 3 year =0.42±0.59 mm).
Discussion: This study showed that early loading of TiOblast™ implants with MicroThread" is associated with similar level of implant survival (94.4%) compared to single tooth implants of the same type conventionally loaded.
With regards to soft tissue healing and early loading protocols, this study clearly showed on a rapid and predictable reproduction of the peri-implant mucosa. No tissue recession was observed, as previously reported in the literature. The favourable results were attributed to the minimal bone level change, early delivery of well performed provisional restorations and to the stability of the connection of the abutment to the implant (absence of abutment screw loosening).
Minimal and limited marginal bone remodelling was found and there were no abutment related complications. The early loading protocol did not influence the preservation of the marginal bone which is in accordance with previously reported results. Again, the results are an effect of the design features of the Astra Tech implant system, having minute threads on the implant neck, an inner conical connection of the abutment to the implant, and a moderately rough implant surface.
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