[Gingival hyperplasia in pregnancy. II. Etiopathogenic factors and mechanisms].

The principal aspects of the hyperplastic pathology which frequently appears during pregnancy with a particular regard to the etiopathogenetic hypotheses are presented. The etiopathogenesis of the so-called pregnancy granuloma is rather complex, because in addition to the common irritant factors like bacterial plaque and calculus it is necessary to recognize the influence that hormonal modifications in pregnancy have on the predisposition to the development of gingival lesions. The hormonal influence acts by an intense inflammatory response and by a selective growth of some periodontal-pathogen and aggressive microbes, like Prevotella intermedia, whose increase in the subgingival plaque from the 3 degrees-4 degrees month of pregnancy coincide with the beginning of hyperplastic lesions. Sexual hormones seems to act as growth factors for the subgingival bacterial flora, in particular for Gram-negative anaerobic rods. The worsening of gingival conditions appears prevalently in the first quarter of pregnancy, in concomitance with the increase of urinary excretion of gonadotropins, that is in relation with an increased concentration of estrogens and progesteron in circulating blood. Sexual hormones could cause great modifications in peripheric vascular system, with a marked increase of vascular permeability and the following oedema of gingival tissues. In pregnancy the maternal immunological system presents some particular modifications, that allows to avoid the immunological rejection between mother and fetus, but reduce the reactivity of gingival tissues against local irritating factors.