Objectives: One aim of this in vitro study was to evaluate the influence of saliva on the formation of CaF2 during application of a fluoride gel. The second aim was to study dissolution behaviour of the produced CaF2 precipitate.
Methods: 160 bovine enamel specimens were divided among two experimental groups. 80 specimens (group I) were treated with a mixture of saliva and Elmex gelée (1:1, 6250 ppm F-, pH: 5.0) and 80 specimens (group II) were treated with a mixture of Elmex gelée and distilled water (1:1, 6250 ppm F-, pH: 5.0) for 5 minutes, respectively. Subsequently the samples were cleaned. Each 40 specimens of the two experimental groups were stored in saliva or in distilled water for 5 days. Saliva and distilled water were replaced daily. After 1h, 24h, 48h, and 120h each 10 samples were removed from the respective storing media and KOH-soluble fluoride (µm/cm²) was determined.
Results: 1h after application of the different mixtures a significant amount of KOH-soluble fluoride could be detected. During the five day period a significant loss of KOH-soluble fluoride could be observed in all groups (p<0.01, ANOVA). Specimens stored in saliva experienced a retarded decrease of KOH-soluble fluoride.
|
Group |
Group I |
Group II |
||
|
Time / storing solution |
Saliva |
Distilled water |
Saliva |
Distilled water |
|
1h |
16.4 ± 6.6 |
18.0 ± 15.7 |
14.4 ± 3.2 |
9.1 ± 5.6 |
|
24h |
11.8 ± 4.1 |
1.7 ± 1.2 |
19.2 ± 8.0 |
2.3 ± 1.4 |
|
48h |
7.4 ± 4.4 |
1.9 ± 1.1 |
9.6 ± 5.8 |
1.8 ± 0.9 |
|
120h |
4.8 ± 3.4 |
2.0 ± 0.8 |
5.1 ± 3.0 |
2.8 ± 3.9 |
Conclusions: The presence of salivary constituents during application of the fluoride gel has a minor influence on the subsequent dissolution behaviour. However, saliva exerts a certain protection function on dissolution of a previously formed CaF2 layer.