The parts of pathogenesis gastrointestinal diseases form relationship with changes in oral cavity. High microbial density bacterial community, consisting of conditionally-pathogenic type and occupying oral mucosa and other parts to oral cavity permits the quick development of the different forms of the pathological processes in oral cavity. The Concept preventive and medical action, conducted in oral cavity of children with chronic gastrodyodenitis, includes: undertaking the diagnostics of the change of microbiocenosis, estimations of the factors of local homeostasis with determination degree of the changes of disbiosis, the individual planning and strictly realization pathogenesis motivated complex action on treatment and preventive maintenance, observation with recommended frequency, including all mentioned elements. One of the significant problems solved by dentist and physician is a shaping among children and teenager with chronic gastritis and gastrodyodenitis, as well as their parents, installation on sound lifestyle. The Advisable frequency observations by dentist this children: in 1 year of the disease: 1 once at 3 months (4 times per annum); in 2 year of the disease: - not less 3 once a year; in 3 and the following years: not less 2 once a year.