Immediate implants at fresh extraction sockets: an experimental study in the beagle dog comparing four different implant systems. Soft tissue findings

P>Objectives To evaluate whether different implants placed immediately upon tooth extraction may affect the dimension and composition of the peri-implant soft tissues. Material and Methods Eight beagle dogs received implants randomly installed into the distal socket of 3P3 and 4P4. Four commercially available implant systems were evaluated: 3i Osseotite Certain straight; Astra MicroThread (TM)-OsseoSpeed (TM); Thommen SPI Element (R); and Straumann ITI standard. Each animal provided four test implant sites. All animals were sacrificed 6 weeks after implant placement, providing specimens for the evaluation of the soft tissue dimensions by histometric analysis. Results The biological width at 6 weeks after implant placement consisted of a junctional epithelium measuring between 2 and 2.7 mm and a connective tissue component between 1 and 1.8 mm with no statistical differences among the four implant systems. Conclusion This study failed to demonstrate differences in the soft tissue healing outcome when placing four different implant systems into fresh extraction sockets. Nevertheless, the length of the epithelium achieved with the four implant systems is longer than what has been reported when placing implants in healed-ridge experimental models.