The aim of the investigation was to evaluate the effect of chlorhexidine gel treatment on caries development of approximal tooth surfaces and on salivary counts of Streptococcus mutans. 220 12-year-old schoolchildren, divided into three groups, participated: (1) chlorhexidine gel group (n = 72), (2) placebo gel group (n = 77), and (3) control group (n = 71). The study was carried out double blind with respect to the two gel groups. Group 1 was treated 4 times/year with 1 % chlorhexidine gel and group 2 with a placebo gel. Approximately 1 ml of gel was applied interdentally by means of a flat dental floss. The control group did not receive any gel treatment or flossing. Number of S. mutans in the saliva was estimated on five occasions during the study with the spatula method. After 3 years, the mean approximal caries increment, expressed as new DFS, was 2.50 in the chlorhexidine gel group and 4.30 in the placebo gel group (p < 0.05). The corresponding figure in the control group was 5.25 (p < 0.001 when compared to group 1). 44% of the children in the chlorhexidine gel group and 32% in the placebo gel group did not develop any new approximal caries lesion during the 3-year observation period compared to 18 % in the control group (group 1–3 p < 0.001; group 2–3 p < 0.05). The number of new approximal fillings (FS) was 0.24 in the chlorhexidine gel group, 0.75 in the placebo gel group and 0.82 in the control group (group 1–3 p < 0.01; group 2–3 p < 0.05). There was no statistically significant difference between the groups with respect to numbers of S. mutans in saliva. However, there were more individuals with low numbers of S. mutans in the chlorhexidine gel group at the final examination compared to the baseline level (p < 0.05).

The aim was to evaluate the effect of chlorhexidine gel treatment on the incidence of approximal caries in preschool children. One hundred and seventeen 4-year-olds, divided into two groups, participated: (1) chlorhexidine gel group (n = 59), and (2) placebo gel group (n = 58). Group 1 was treated 4 times a year with a 1% chlorhexdine gel and group 2 with a placebo gel. Approximately 0.7 ml of gel was applied interdentally by means of a flat dental floss. A control group (group 3), which did not receive any flossing or gel treatment, was also included in the study (n = 116). After 3 years, i.e. when the children were 7 years old, the mean incidence of caries on approximal surfaces (defs), including both enamel and dentin lesions, was 2.59 in the chlorhexidine gel, 4.53 in the placebo gel and 4.20 in the control group (group 1 vs. 2 and group 1 vs. 3: p < 0.01). Mean number of approximal fillings at the end of the study, i.e. when the children were 7 years old, was 0.33 in the chlorhexidine gel, 1.04 in the placebo gel and 0.80 in the control group (group 1 vs. 2: p < 0.01; group 1 vs. 3: p < 0.05). The progression of approximal caries lesions, diagnosed on bitewing radiographs from the age of 5 to 7, was slower in the chlorhexidine than in the placebo gel group (the control group was not evaluated in this respect). A cost analysis, based on the total treatment time in minutes, showed a small gain for the flossing program. Thus, the results indicate that professional application 4 times a year of chlorhexidine gel in combination with dental flossing has a caries-reducing effect on approximal caries in primary teeth.

The aim of this study was to evaluate the effect of professional flossing with NaF and SnF2 gels on caries development on approximal tooth surfaces. Two-hundred-and-eighty 13-year-old schoolchildren were divided into 3 groups: (1) NaF (n = 97), (2) SnF2 (n = 85), and (3) placebo gel group (n = 98). The investigation was carried out double-blind. The children were treated 4 times a year for 3 years with 1% NaF gel, 1% SnF2 gel, or placebo gel. The treatment was carried out by dental nurses and the time required per visit was approximately 10 min. After 3 years, the mean approximal caries increment, including initial caries lesions, was 2.8 in the NaF, 2.4 in the SnF2, and 4.0 in the placebo gel group (P< 0.05 for SnF2 vs placebo); a reduction compared to the placebo of 30% and 39% in the NaF and SnF2 groups, respectively. Thus, professional flossing with NaF or SnF2 gel carried out 4 times a year may be considered as an interesting caries-preventing method for large-scale application in schoolchildren.

We have in two earlier studies evaluated the effect of professional flossing with chlorhexidine (CHX) gel treatment, in 4- to 7-year-old preschool children and in 12- to 15-year-old teenagers. The mean caries reduction after 3 years was around 40% compared to placebo gel or no gel treatment. The aim of the present investigation was to follow up these two clinical studies. The preschool children were followed up to the age of 16 years and the teenager group to the age of 19. Of the total number of original children, 71 and 80% were available at the age of 16 and 19 years, respectively. At the 9-year follow-up, when the children were 16 years old, the former CHX group had still significantly lower mean DFS than the control group (p < 0.05). The differences in caries increment occurred between 7 and 12 years of age, whereas the number of new caries lesions during the next 4 years were almost the same in the three groups. At the 4-year follow-up, when the teenagers were 19 years old, DFS was 6.9 in the former CHX group compared to 10.4 in the control group (p < 0.05). The main conclusion of these two follow-up studies after 9 and 4 years, respectively, is that caries reductions obtained at the end of professional flossing with a 1% CHX gel were maintained.