A clinical, radiographic, and microbiologic comparison of Astra Tech and Brånemark single tooth implants

The soft tissues around single tooth implants differ fundamentally from the gingiva around natural teeth. There are very limited data comparing soft tissues around different implant systems.

To assess whether the design characteristics of dental implants, particularly the implant-abutment junction, may affect the dimensions and health of the peri-implant soft tissues and radiographic bone levels.

Fifteen Astra Tech and 15 Brånemark single tooth implants that had been in function for a minimum of 2 years in 30 partially dentate subjects were examined for plaque accumulation, probing depth, and bleeding on probing and compared to contralateral healthy teeth. Standardized radiographs were taken to measure the most coronal bone to implant contact on the mesial and distal surfaces. In addition, samples of subgingival plaque were taken on paper points and examined by darkfield microscopy.

Significantly higher mean probing depths (p < .001) and higher mean percentage of spirochetes (p = .003) were found at implants compared to teeth. In this sample, the Brånemark implants had significantly higher probing depths than the Astra Tech implants (median and interquartile range: Astra Tech 2.7 mm [2-3], Brånemark 3.3 mm [3-3.7] p = .026) and the most coronal bone to implant contact was closer to the implant-abutment junction in the Astra Tech implants (Astra Tech 0.6 mm [0.2-0.9], Brånemark 1.6 mm [1.4-2.0]. p < .001).

Although there were statistically significant differences between the two implant systems, the clinical differences were small and probably reflect differences in the biologic width in relation to the location and design of the implant-abutment junction.