Evaluation of bacterial leakage rate at the interface of ITI fixtures and ITI, DIO and OSSTEM solid abutments

One of the most concerns about the use of implant treatments is bacterial leakage between the fixture and abutment at the connection. The aim of this study was to evaluate the bacterial leakage rate at the interface of ITI fixtures and ITI, DIO and OSSTEM solid abutments.

Thirty ITI fixtures were divided into three groups (n=10) based on the abutment used. In the first group, 10 solid ITI abutments, in the second group, 10 solid DIO abutments, and in the third group, 10 solid OSSTEM abutments with similar length and diameter were screwed into fixtures. Fixtures and abutments were assembled and allowed to incubate in a solution of Streptococcus faecalis (SF) for 5 days. In each group, two additional fixtures and two abutments were selected and divided into two subgroups. In the negative-control subgroups, abutments were not connected to fixtures and were placed into normal saline solution. In the positive-control subgroup, abutments were not connected to fixtures but were subjected to the same bacterial solution. After disconnection of fixtures and abutments under sterile condition, abutments and fixtures were placed in 1ml of normal saline solution and were vortexed for 30 sec. Then, 0.01 ml of each vortexed solution was cultured under appropriate conditions for 2 days. The CFUs (colony forming unit) were counted and recorded for each abutment and fixture.

The average of CFUs for each abutment and fixture counted in the first group was 13.6 and 20, in the second group was 21.9 and 28.9, in the third group was 26.2 and 35.9, in positive control subgroup was 152.3 and 178.3, and in negative-control subgroup was 0 and 0, respectively. There were not statistically significant differences between the first and second groups but the leakage rate was statistically different between first and third groups.

The results of the present study demonstrated that compatibility of DIO solid abutments on ITI fixtures are acceptable but it is not the case for OSSTEM solid abutments and the use of these abutments on ITI fixtures is not recommended.