OsseoSpeed™ is the implant with a chemically modified surface and a unique nanoscale topography. The OsseoSpeed implant has clearly improved results compared to earlier generations of implants. The following summaries of the pre-clinical and clinical scientific articles reveal the mechanisms behind the performance and clinical outcome.
Bone healing at implants with a fluoride-modified surface: an experimental study in dogs
Purpose: In the early loading or immediate loading protocol for dental implants it is recognized that a process occurs during the initial healing phase which transfers the retention of the implant from a mechanical to a biological phenomenon over a period of approximately 4 weeks. During this osseointegration phase a coagulum is seen to re-organize with granulation tissue which is subsequently replaced by a matrix that leads to new bone formation. The need to enhance or optimize conditions for osseointegration of the implant during this critical phase is important and has been shown to be improved by surface microtexturing. In addition some studies have indicated that there may be some additional benefits derived from biochemical modifications, in particular the addition of fluoride ions on to the surface of the implant. This study set out to evaluate the effects of fluoride on the early stages of osseointegration by histological examination.
Materials and Methods: Six mongrel dogs had all their mandibular premolars and first mandibular molars extracted. Three months later one side of the mandible was exposed and 6 implants were placed. Two geometrically identical implants were used, and both were equipped with MicroThread'" on the implant neck. The control implants had a TiOblast"' surface (TiOblasr, Astra Tech), (TB) and the test implants had a fluoride modified surface (OsseoSpeed", Astra Tech) (OS). The surface roughness (Sa) was moderate in both cases and were for TB 1-1.2 pm and for OS 1.4-1.5 fjm. Four weeks after the first implants were randomly placed the procedure was repeated on the contralateral side of the mandible. After a further 2 weeks of healing the animals were sacrificed, and each implant was removed en bloc and prepared for histological analysis of either fractured decalcified 3 pm sections stained with toluidine blue or 20 /im ground sections also stained with toluidine blue. The degree of bone-to-implant contact (% BIC) was assessed within the micro and macro-threaded portion of all the implants. The tissue filling the void between the cut bone wall and the macro-threads of the implant immediately following implant installation was also evaluated to study early bone formation. Differences between the implant types were analyzed using student's t-test, at the 95% confidence level.
Results: Healing was uneventful and no implants were lost. After 2 and 6 weeks the % BIC at the MicroThread portion of both the TB and OS implants were similar. In the macro-threaded portion at 2 weeks the % BIC was 57% for the OS implants and 43% for the TB implants, (p < 0.05). At 6 weeks respective values were 61% and 59%. The % BIC in the wound chamber showed a significant difference at 2 weeks with 72% for OS implants compared to 60% for the TB implants, (p < 0.05). At 6 weeks respective values were 61% and 67%.
With respect to the tissue composition, after 2 weeks the wound chamber had 25-30% mineralized bone, which mainly consisted of woven bone (approx 20%). The amount of mineralized bone increased to approximately 50% at 6 weeks with a significant decrease in the constituent proportion of woven bone which had been replaced by lamellar bone. Tissue composition and proportion was similar at both TB and OS implants.
Discussion and Conclusion: Previous studies have demonstrated the influence of surface roughness to enhance the rate of early bone formation and osseointegration. Typically these studies have compared roughened implants to machined implants where differences in the Sa values are considerable. In the current study a microtextured implant was used as the control and as such had a similar Sa value to that of the test implant which was modified only by the incorporation of fluoride ions. The finding that there was significantly more new bone formed within the wound chamber and along the macro-threaded portion of the OS implant surface at 2 weeks is noteworthy since it suggests that the fluoride modified surface enhances and promotes osseointegration in the early phase of healing following implant installation and that in this particular test it was not dependent on surface roughness. These findings are in agreement with previously published data from Ellingsen et al (JOMI, 2004) and Cooper et al (Bio-materials, 2006) which would imply that osteoblast differentiation and new bone formation is enhanced by the addition of fluoride.