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.
A prospective 5-year study of fixed partial prostheses supported by implants with machined and TiO 2-blasted surface
Purpose: This prospective study set out to record and compare Astra Tech implants and the marginal bone loss at implants with a machined (M) and a roughened (TiOblast'M, TB) surface when used to support fixed partial prostheses over a 5-year follow-up period.
Materials and Methods: 50 patients were enrolled in the study and presented with partially edentulous spans of at least one year standing. In the maxilla 45 implants were placed (M = 25 and TB = 20) and 83 implants were inserted into the mandible (M = 39 and TB = 44). Each patient received the two surface types alternately to allow a within patient comparison. Equal numbers of the two surface types were placed (n = 64/surface). Surgery was performed according to manufacturer's recommendations with a submerged healing of 3 to 7 months depending on the jaw. At abutment connection the standard Uni-Abutment was connected. All partial prostheses were screw-retained and insertion was always within two months of postoperative healing at which time baseline radiographic and clinical data was recorded.
Clinical data was collected annually and included assessment of mobility, parasthesia and inflammation (defined according to a protocol). Any technical complications with either the components or prostheses were also noted. In addition patients were independently asked to grade function and esthetics as good, moderate or poor.
Intra-oral annual radiographs were taken in a standardized manner. Marginal bone levels were assessed by an independent radiologist to determine the amount of bone loss on the mesial and distal surfaces of each implant to the nearest 0.1 mm. Statistical analysis was performed at the end of the 5-year recall to determine the difference between survival rates and marginal bone loss for the two implant surfaces. In addition, one implant of each type was selected for each patient to allow a within patient comparison.
Results: Ten patients with 16 implants were lost to follow-up. Over the five year study period 3 machined implants failed resulting in cumulative survival rates of 95.1% and 100% for M and TB implants respectively. Mean marginal bone loss measured 0.21 mm and 0.51 mm for M and TB implants respectively with only 5 implants recording a bone loss of > 2.0 mm. These differences were not statistically significant. At the end of the study period, 6% of both types of implant were associated with mucosal inflammation.
With regard to technical complications only 2 abutments fractured within 2 years of function. Five abutments required retightening. A total of 12 bridge screws in 7 patients required retightening and 2 bridges were remade. 100% of patients recorded the function as good and 79% recorded the esthetics as good at the 5-year recall.
Discussion: The current study demonstrated survival rates for both machined and TiO3-blasted Astra Tech implants which fall well within the criteria for success set out by Albrektsson et al. There were 3 failures, all of which were implants with the machined surface. In regards to change in marginal bone level between the two groups differences were not statistically significant and fell well within established criteria for success. The most common technical problem of bridge screw loosening was restricted to prostheses supported by two implants only.
Astra Tech
BioManagement Complex 
