Quantitative analysis of the impact of the organic matrix on the fluoride effect on erosion progression in human dentine using longitudinal microradiography

After an initial demineralisation, an intensive fluoridation is capable of inhibiting the erosive mineral loss in dentine completely, which might be related to the presence of the exposed organic dentine matrix. Aim of the present study was, therefore, to evaluate whether fluoride is also effective when the organic material is removed. udy was a cyclic de- and remineralisation model over 5 days in vitro. Samples from human coronal dentine were demineralised with citric acid (pH 2.3; 6 × 10 min per day) and intermittently stored in a remineralisation solution. Groups (n = 25 each) were defined as follows: Group 1: erosion only, no fluoridation; Group 2: erosion, alternately fluoridation with toothpaste (NaF; 0.15% F−; 3 × 5 min per day), mouthrinse (Olaflur/SnF2; 0.025 F−; 3 × 5 min per day) and gel (Olaflur/NaF; 1.25% F−; at Days 1 and 3 instead of one toothpaste application); Group 3: erosion and fluoridation as Group 2, organic material was continuously removed with collagenase (from Clostridium Histolyticum type VII, 100 U/ml) added to the remineralisation solution. Mineral content was monitored daily using longitudinal microradiogaphy. fluoridation in the presence of collagenase, a linear increase in mineral loss (73.3 ± 17.6 μm at Day 5) was observed, which significantly (P ≤ 0.001) exceeded that of the control group (45.9 ± 14.3 μm at Day 5). After fluoridation in the absence of collagenase, mineral loss ceased after the 2nd day (12.2 ± 10.2 μm at Day 5) and was significantly lower compared to Groups 1 and 3 (P ≤ 0.001). sults indicate that the dentine matrix is essential for the effectiveness of fluoride in dental erosion.