**5. Summary**

Taking into consideration a high prevalence and intensification of caries of lateral teeth in children, apart from other methods of caries prophylaxis, such as contact fluorization, which protects flat and contact surfaces of teeth - it is advisable to apply fissure sealants of lateral teeth, i.e. molars and premolars, starting with freshly erupted permanent first molars through subsequently erupting posterior teeth. In order to decrease caries prevalence in our population, it is necessary to conduct awareness-forming oral hygiene training, to create motivation for proper tooth brushing, to advise a diet aimed at reduction of carbohydrate consumption and elimination of additional meals.

Results of numerous laboratory tests indicated that extension of enamel etching time significantly increased the stability of bonds with sealing material. Application of intermediate adhesive systems on enamel increased the strength of enamel bonding with sealing materials only slightly, whereas their application on dentine significantly improved bonding stability (about threefold) compared to dentine coated with sealant alone. An assessment of morphology of dentine joints where dentine was coated with bonding agents and sealant demonstrated occurrence of gapless joints, whereas when sealant was applied directly on dentine, joints with microcracks were formed. Elements included in sealing materials and adhesive systems penetrate into dentine deep and wide, improving retention and tightness of bonding with hard tissues of teeth.

Sealants with fluorine release it into hard tissues of teeth. The level of emission depends on type of fluorine compound and its concentration in sealant. On the basis of literature analysis and own longitudinal clinical studies as well as laboratory tests I confirm the advisability of sealing procedure, expanding it not only on permanent first molars, but including also second molars and - in children requiring special care and having a high caries risk - premolars. Laboratory tests confirmed that that adhesion and tightness of joints between sealants and tooth's hard tissues can be increased, and microleakage can be minimized.
