Over the last decade, there has been a decline in dental caries prevalence among children and adolescents. Nevertheless, dental caries is still a major health problem worldwide, affecting as many as 60 – 90% of children. While some decrease in caries prevalence has been observed, the number of caries lesions developed on occlusal surfaces remains high. The occlusal surfaces of both the first permanent molars (FPMs) and the second permanent molars (SPMs) have the greatest risk of caries development. Although the occlusal surface represents only 15% of all dental surfaces, as much as 88% of all caries lesions develops in pits and fissures of FPMs and SPMs.
Fissure sealants are effective caries preventive measure. However, a dilemma has been expressed more than once, whether incompletely sealed fissures provides sufficient protection against caries. Dental examinations were performed in 88 children, aged 8 and then four years later at age 12. All first permanent molars (FPMs), as diagnosed at the age of 8, were divided into three groups: nonsealed, incompletely and completely sealed. Four years later caries incidence and changes in presence and quality of fissure sealant were analyzed. At the age of 8 and 12 mean DMFT (Decayed, Missing due to caries, and Filled Teeth) were 0.73 ± 1.24 and 3.48 ± 3.04, respectively. 71.59% of the 8‐year‐olds and 78.41% of the 12‐year‐olds had at least one sealed FPM. At the age of 8, 154 FPMs were completely sealed and 42 FPMs were incompletely sealed. Four years later, 81.17%, 71.43% and 69.4% of FPMs were healthy (sound or with noncavitated caries) in the baseline groups completely sealed, incompletely sealed and nonsealed FPMs, respectively. Incompletely sealed fissures were more susceptible to caries development than completely sealed fissures. It is important that incompletely sealed fissures are resealed as soon as possible.