[Effect of the working environment in the petrochemical industry on the periodontium and mucous membrane of vocational school students].

The clinical dental examination was carried out at 6 months intervals in a group of 41 vocational school pupils exposed to chemical hazards in the petrochemical industry and a control group consisting of 30 pupils of an economic grammar school. The paradontium and mucous membrane of vocational school pupils before occupational exposure was worse than that of grammar school pupils. Pupils exposed to working environment hazards exhibited an increased rate of paradontium diseases.