In this prospective longitudinal study 346 implants were inserted in 115 patients using a flapless surgical protocol. The follow-up period started 1 year after prosthetic loading.

Two-piece titanium implants (Straumann, Thommen) and one-piece zirconium-dioxide implants (Z-Systems) were compared in terms of soft tissue findings.

The influence of keratinized tissue on peri-implant health was examined.

The overall survival rate of the implants was 99.8% after a mean follow-up period of 3 years and 8 months.

Positive bleeding score (BOP) was found at 106 of the 346 implant sites (30.63%). A significant difference was recorded between Straumann implants (14.9%) and Thommen implants (38.2%) BOP for the zirconium-dioxide Implants was 0%.

The bleeding score was significantly higher for those implants without keratinized mucosa. 161 (68.5%) Straumann implants and 74 (72.5%) Thommen implants were surrounded by a band of keratinized tissue. Only 38 Straumann (26.4%) and 22 Thommen (30.6%) implants showed positive bleeding on probing. 8 from 9 Z-System implants were placed in keratinized mucosa and none showed any signs of inflammation.

Conflict of interest: None declared.