The facts behind the figures
How did we come to the conclusion that the ASTRA TECH Implant System™ has an average marginal bone level reduction of less than 0.3 millimeters after the first year of loading and that it remains stable after five years?
A total of 32 scientific articles reporting average changes in marginal bone levels with ASTRA TECH Implant System were found, according to a literature search of publications in English peer reviewed scientific journals, January 2011. Inclusion criteria for the 32 studies were:
- prospective, radiological studies presenting bone level values from loading to follow-up visits
- full cohort studies (minimum of 10 patients)
- standard protocol (no bone augmentation, immediate installation and/or immediate loading protocols)
- 1 to 5 years follow-up
The results from the 32 scientific articles are:
- The 14 prospective, full cohort studies demonstrate that with ASTRA TECH Implant System the average marginal bone level reduction 5 years after loading is less than 0.3 mm (average value 0.22 mm, range +0.12 mm to 0.48 mm) (4–17).
- The 6 prospective, full cohort studies demonstrate that with ASTRA TECH Implant System the average marginal bone level reduction 3 years after loading is less than 0.3 mm (average value 0.23 mm, range 0.01 mm to 0.42 mm) (18–23).
- The 7 prospective, full cohort studies demonstrate that with ASTRA TECH Implant System the average marginal bone level reduction 2 years after loading is less than 0.3 mm (average value 0.26 mm, range 0.01 mm to 0.66 mm) (24–30).
- The 5 prospective, full cohort studies demonstrate that with ASTRA TECH Implant System the average marginal bone level reduction 1 year after loading is less than 0.3 mm (average value 0.19 mm, range 0.05 mm to 0.40 mm) (31–35).
When the ASTRA TECH Implant System data was presented to Tomas Albrektsson, Professor of Biomaterial Research at the Sahlgrenska Academy, University of Gothenburg, Sweden, one of the authors of articles from 1986 and 1993, he said in a press release*:
“The limited marginal bone resorption being documented on ASTRA TECH Implant System indicates that it is time to reconsider our old ‘standard’ from 1986. The new standard should perhaps only allow 50% or less of the bone resorption currently accepted as a successful result.”
It is certainly time to set a new standard.
* Unique data presented on ASTRA TECH Implant System: challenges current standard for success!, June 4, 2008.