The Astra Tech Implant System™ is designed and proven clinically to maintain marginal bone. Outstanding long-term (i.e. > 5 years) clinical results on the maintenance and preservation of the marginal bone is summarized here. Some of the articles even report on marginal bone gain around Astra Tech implants in several patients.
Marginal bone level changes at dental implants after 5 years in function: A meta-analysis
Since the introduction of titanium dental implants many modifications have taken place, not only with respect to implant design, and treatment protocol but also with regard to patient expectations for esthetics and longevity of function. Implant success has previously been determined by a number of factors, most notably maintenance of marginal bone and the avoidance of a peri-implant infection. Established criteria have identified a marginal bone loss of 1 mm in the first year of function and 0.2 mm for each year thereafter as a minimum measure of success, however little is known about how modern implants fair against these historic criteria, which may require revision.
Purpose: This meta-analysis was set up to compare data on marginal bone levels for those systems with a published 5-year follow-up and with full radiographic data.
Material and Methods: Only systems currently available on the market were included in the meta-analysis, and each system had to have at least 2 studies with a minimum of 5 years follow-up to be included. Case cohort studies with a minimum of 10 cases were included in the analysis, along with prospective clinical studies. Only studies reporting data on implants placed using conventional surgical protocols were included, thus immediate implants were excluded from the analysis.
The literature was searched using PubMed from 1980 to 2007 using appropriate keywords. In addition a manual search was undertaken of the most prominent implant, periodontal and prosthetic journals. Finally the websites of 8 leading brands were also searched for any further data. Data from all studies was pooled for statistical analysis to determine the presence of any differences between systems for changes in the marginal bone levels (MBL) at the level of p < 0.05.
Results: Of 293 viable articles, 68 were selected for further screening which yielded a total of 40 articles that fulfilled the inclusion criteria. These 40 articles only represented 3 implant systems, with 19 articles on the Branemark System (BS) (n = 3719 implants), 11 articles on the Straumann System (SS) (n = 1364 implants) and 10 on the Astra Tech Implant System™ (ATS) (n = 1187 implants). The pooled mean changes in MBL were calculated to be -0.24 mm (ATS)
< -0.48 mm (SS) < -0.75 mm (BS). The data was then subject to weighting by number of patients, which yield means of -0.27 mm (ATS) < -0.56 mm (SS)
< -0.72 mm (BS). The difference between systems was statistically significant, p < 0.01. Furthermore it was noted for the BS and SS that there were significantly larger ranges between changes in MBL when comparing the different studies, yielding larger standard deviations than seen for the ATS.
Discussion and Conclusions: Only 3 systems fulfilled the necessary criteria of having at least 2 studies with 5-year data on changes in MBL. Only the ATS was documented predominantly using controlled clinical studies, while the BS and SS were documented by means of case cohorts. Only ATS studies offered both mean and standard deviation data, while this had to be extrapolated from studies on the other 2 systems.
In order for adequate data to make the analysis meaningful no differentiation was made between jaws treated, tooth positions, or prosthesis types. All data was pooled. This might explain the differences between the systems for MBL values, or it may be due to speculated differences in implant design. In any event the data from the ATS was more robust with only a small standard deviation right across the 10 studies and bone loss values ranging from +0.12 mm to -0.48 mm as compared to -0.15 mm to -1.0 mm for the SS and -0.11 to -1.80 mm for the BS.
The current meta-analysis would indicate that a revision of the established criteria for success as determined by changes in MBL should be made since very few implants appeared to lose 1.0 mm of bone in the first year and over 5 years the ongoing MBL ranged from 0.05 mm to 0.10 mm for the systems under review. It can be concluded that only these 3 implant systems can offer scientific evidence for long-term maintenance of marginal bone levels.
Astra Tech
BioManagement Complex 
