Among the various pathologies of the oral cavity, the formation of "unsightly black spots" on the surface of the tooth, universally known as Black Stain (BS) has recently been acquiring more interest. Usually BS is typically found in individuals in prepubertal age, even though it has been identified in adults associated with microbial exchange and / or with iron metabolism disorders. Microbial exchange concerns the possible exchange of bacteria between family members which can take place directly, through effusions, or indirectly, through brushes, cutlery or glasses. For this reason, it is recommended that toothbrushes of family members not be left damp and in contact with each other. The bathroom, being a warm-humid environment, is in fact an optimal habitat for microbial proliferation. Of specific importance in BS is the accumulation of iron in tissues and secretions which, together with chromogenic bacteria, are the primary cause of this pathology. In fact, among the metabolic products synthesized by bacteria in the oral cavity, hydrogen sulfide is of considerable interest, since upon reacting with iron available in saliva, in pathological conditions (iron metabolism disorders), it forms black precipitates consisting of ferric sulfide. These precipitates bind to the surface of the teeth, tending to form a stria that usually follows the contour of the gingiva, with an unsightly and variable chromatic intensity. In physiological situations, iron homeostasis is defined as the state of equilibrium between iron present in tissues and in secretions and that which is present in the circulation. Instead, in pathological conditions, defined as iron metabolism disorders, there is an accumulation of iron in tissues and secretions and a lack of it in the circulation. It is also important to remember that subjects affected by BS are more protected from carious processes than healthy subjects, probably due to a significant predominance of chromogenic bacteria compared to those responsible for caries. It should also be remembered that in young subjects BS tends to regress with pubertal development and the transition to adult life. In any case, using common professional hygiene procedures, it is possible to remove BS as well as plaque and tartar deposits. In particular, with ultrasonic scalers, polishing pastes and powders carried by air and water jets, the surfaces of the teeth can be restored to their natural healthy state. All the techniques for removing the precipitates, are not enough however, to fix and permanently eradicate their appearance, as these precipitates last only for short periods and recur very frequently. Due to the frequent recurrences, new oral microbiota control therapies are emerging; among these the use of lactoferrin (Lf) in the dental field and particularly in the treatment of BS appears to be very promising. Taken togheter, here the effect of Lf in subjects affected by BS has been investigated.
Keywords: Black stain; Iron metabolism; Lactoferrin; Oral disorders; Saliva.