Retrospective investigation of gingival invaginations: Part II: microbiological findings and genetic risk profile

Gingival invaginations are a frequent finding during tooth extraction and following orthodontic space closure. Based on the interdental localization and sometimes pronounced depth, it has been suggested that a gingival invagination may impede oral hygiene. In Part I of this series, the time until active tooth movement and the localization of extraction were identified as potential risk factors for the development of gingival invagination. The aims of the present study were the analysis of the microbial spectrum of a gingival invagination in comparison with pool samples of the sulcus of Ramfjord teeth, on the one hand, and the importance of genetic variations of the pro-inflammatory mediator interleukin-1 (IL-1) and its receptor antagonist (IL-1-RN), on the other hand. In addition, a possible role of smoking as a risk factor was evaluated.

A total of 30 patients with (n=16) and without (n=14) gingival invagination were examined for the presence of eleven periodontal pathogen bacterial species with a commercially available test (micro-IDent®Plus, Hain Lifescience, Nehren, Germany). The genetic evaluation was performed with the GenoType® IL-1 test (Hain Lifescience).

The results of the microbiological analysis of gingival invaginations showed that the bacterial flora might differ or even be higher than the pool sample from sulcus regions. The genetic evaluation demonstrated that in the group without gingival invagination only 14% showed an IL-1 polymorphism, whereas this value was twice as high (35%) in the group with gingival invagination. In addition, a combination of both polymorphisms IL-1 and IL-1-RN was only found in patients with gingival invagination (25%). Interestingly, smoking patients showed a significant increase of the severity of the gingival invagination.

This retrospective study demonstrated that gingival invagination might be accompanied with an altered microbiological bacterial spectrum and a genetic IL-1 polymorphism. In addition, smoking was identified as another potential risk factor for the severity of gingival invaginations.