J. Klimek

Effects of two fluoridation measures on erosion progression in human enamel and dentine in situ.

The aim of the present study was to evaluate the effects of fluoride on erosive mineral loss in human enamel and dentine using a cyclic de- and remineralisation model in situ. The study was a three-treatment (5 days each) crossover design involving 4 (enamel) or 6 (dentine) healthy volunteers. Samples were recessed in palatal mouth appliances and worn day and night except during meals and were demineralised extraorally with 0.05 M citric acid (pH 2.3) for 6 × 5 min daily. Fluoridation was performed with toothpaste (SnF2/Olaflur; 0.14% F–) for 3 × 5 min daily (toothpaste fluoridation) or with toothpaste in combination with a mouthrinse (SnF2/Olaflur; 0.025% F–) for 3 × 5 min daily and with a gel (NaF/Olaflur, 1.25% F–) on days 1 and 3 instead of the toothpaste (intensive fluoridation). In the control group no fluoridation was performed. Mineral loss (µm) was determined with the use of longitudinal microradiography. In enamel, mineral loss was 40.7 ± 15.1 µm in the control group, 18.3 ± 12.4 µm after toothpaste fluoridation and 5.0 ± 12.2 µm after intensive fluoridation. The respective values for dentine were 49.0 ± 15.4, 35.0 ± 15.5 and 19.8 ± 12.0 µm. All differences were statistically significant (p ≤ 0.001). The results indicate that intensive fluoridation is effective in preventing enamel and dentine from mineral loss even under severely erosive conditions.

Effect of Fluoride Compounds on Enamel Erosion in vitro: A Comparison of Amine, Sodium and Stannous Fluoride

The aim of the study was to evaluate the relevance of cations in different fluoride compounds for their effectiveness as anti-erosive agents. Human enamel samples underwent a de- and re-mineralisation procedure for 10 days. Erosive demineralisation was performed with 0.05 Mcitric acid (pH 2.3) 6 × 2 min daily followed by immersion in the test solution 6 × 2 min each. Test solutions were: SnCl2 (815 ppm Sn; pH 2.6), NaF (250 ppm F; pH 3.5), SnF2 (250 ppm F, 809 ppm Sn; pH 3.5), amine fluoride (AmF, 250 ppm F; pH 3.5), AmF/NaF (250 ppm F; pH 4.3), and AmF/SnF2 (250 ppm F, 390 ppm Sn; pH 4.2). In the control group no fluoridation was performed. Mineral content was monitored by longitudinal microradiography. Finally, scanning electron microscopy was performed. The highest erosive mineral loss was found in the control group (48.0 ± 17.1 µm). Mineral loss was nearly completely inhibited by AmF/SnF2 (5.7 ± 25.1 µm; p ≤ 0.001) and SnF2 (–3.8 ± 14.4 µm; p ≤ 0.001) treatments. Groups treated with SnCl2 (17.6 ± 19.5 µm; p ≤ 0.001) and NaF (13.2 ± 21.7 µm; p ≤ 0.001) showed a decrease in erosive mineral loss, AmF (41.6 ± 16.0 µm) and AmF/NaF (27.7 ± 28.4 µm) had no significant effect on erosion progression. The results indicate considerable differences between the fluoride compounds tested. Treatment with solutions containing SnF2 was most effective.

A comparative profilometric in vitro study of the susceptibility of polished and natural human enamel and dentine surfaces to erosive demineralization

This study sought to compare the depths of erosive lesions in samples from different tooth sides as well as from enamel, dentine and root surfaces, and to examine the effect of preparation and polishing of specimens on erosive demineralization. From 30 impacted human third molars, two enamel samples from the mesial, distal, buccal and oral aspects, and similar samples from the radicular dentine, were prepared. One of each pair of samples was polished whereas the other was left untreated. Four samples were also prepared from the coronal dentine. For erosive demineralization, all samples were immersed in 0.05 M citric acid for 3 h and the erosion depth was calculated profilometrically. In general, natural surfaces showed significantly smaller erosion depths than polished surfaces (p< or =0.001) and enamel samples showed greater depths than coronal dentine (not significant) and root dentine (p< or =0.001). The erosion depths of the four tooth sides correlated significantly for polished enamel and coronal dentine samples but not for natural enamel specimens. There was no correlation between erosion depths for enamel and coronal dentine, and only a weak correlation between enamel and root dentine.

Effect of Titanium Tetrafluoride and Sodium Fluoride on Erosion Progression in Enamel and Dentine in vitro

Our aim was to investigate the effect of TiF4 solutions on mineral loss on enamel and dentine in vitro. Samples were fluoridated 1 × 5 min per day with 1.64% w/v TiF4 or 2.2% w/v NaF solutions, each with a pH of 1.2, and then subjected to a cyclic de- and remineralization procedure for 5 days. Demineralization was performed for 6 × 10 min per day with citric acid (pH 2.3). In controls no fluoridation was performed. Mineral content was determined by longitudinal microradiography. Enamel mineral loss was markedly reduced by both fluoride solutions, but TiF4 was significantly more effective than NaF: cumulative mineral loss on day 3 was 61.7 ± 15.0 µm in the NaF and 34.2 ± 13.1 µm in the TiF4 group (p ≤ 0.001) compared with 121.0 ± 27.0 µm in the control group. Dentine mineral loss ceased after both TiF4 and NaF applications (cumulative mineral loss on day 5 in controls: 61.0 ± 17.0 µm, in the TiF4 group: 15.4 ± 13.4 µm and in the NaF group: 21.8 ± 11.8 µm). Both TiF4 and NaF application reduced mineral loss both on enamel and dentine, which could open new possibilities for a symptomatic therapy of erosions.

Tin-containing fluoride solutions as anti-erosive agents in enamel: an in vitro tin-uptake, tissue-loss, and scanning electron micrograph study

Tin-containing fluoride solutions can reduce erosive tissue loss, but the effects of the reaction between tin and enamel are still not clear. During a 10-d period, enamel specimens were cyclically demineralized (0.05 M citric acid, pH 2.3, 6 x 5 min d(-1)) and remineralized (between the demineralization cycles and overnight). In the negative-control group, no further treatment was performed. Three groups were treated (2 x 2 min d(-1)) with tin-containing fluoride solutions (400, 1,400 or 2,100 ppm Sn2+, all 1,500 ppm F-, pH 4.5). Three additional groups were treated with test solutions twice daily, but without demineralization. Tissue loss was determined profilometrically. Energy-dispersive X-ray spectroscopy was used to measure the tin content on and within three layers (10 mum each) beneath the surface. In addition, scanning electron microscopy was conducted. All test preparations significantly reduced tissue loss. Deposition of tin on surfaces was higher without erosion than with erosion, but no incorporation of tin into enamel was found without demineralization. Under erosive conditions, both highly concentrated solutions led to the incorporation of tin up to a depth of 20 mum; the less-concentrated solution led to small amounts of tin in the outer 10 mum. The efficacy of tin-containing solutions seems to depend mainly on the incorporation of tin into enamel.

Efficacy of a Tin/Fluoride Rinse: a Randomized in situ Trial on Erosion

Concentrated tin- and fluoride-containing mouthrinses are effective erosion inhibitors in enamel and dentin. To test whether this is also true for solutions with lower concentrations, we conducted a randomized double-blind three-cell crossover in situ study with extra-orally performed erosive impacts (citric acid, 6 x 5 min/day) and an intra-oral rinsing protocol (1 x 30 sec/day) in 24 volunteers. The mouthrinses were a placebo, a NaF (500 ppm F-), and an amine fluoride (AmF)/NaF/SnCl2 mouthrinse (500 ppm F-, 800 ppm Sn2+). Compared with the placebo, the NaF mouthrinse reduced substance loss by 19% in enamel and 23% in dentin (p ≤ 0.01 each); the AmF/NaF/SnCl2 mouthrinse reduced this parameter by 67% in enamel and 47% in dentin (p ≤ 0.001 each). AmF/NaF/SnCl2 was significantly more effective than NaF in both tissues (p ≤ 0.01). The mouthrinse containing Sn and F exhibited good efficacy, even under severe erosive conditions.

Conventional and Anti-Erosion Fluoride Toothpastes: Effect on Enamel Erosion and Erosion-Abrasion

New toothpastes with anti-erosion claims are marketed, but little is known about their effectiveness. This study investigates these products in comparison with various conventional NaF toothpastes and tin-containing products with respect to their erosion protection/abrasion prevention properties. In experiment 1, samples were demineralised (10 days, 6 × 2 min/day; citric acid, pH 2.4), exposed to toothpaste slurries (2 × 2 min/day) and intermittently stored in a mineral salt solution. In experiment 2, samples were additionally brushed for 15 s during the slurry immersion time. Study products were 8 conventional NaF toothpastes (1,400–1,490 ppm F), 4 formulations with anti-erosion claims (2 F toothpastes: NaF + KNO3 and NaF + hydroxyapatite; and 2 F-free toothpastes: zinc-carbonate-hydroxyapatite, and chitosan) and 2 Sn-containing products (toothpaste: 3,436 ppm Sn, 1,450 ppm F as SnF2/NaF; gel: 970 ppm F, 3,030 ppm Sn as SnF2). A mouth rinse (500 ppm F as AmF/NaF, 800 ppm Sn as SnCl2) was the positive control. Tissue loss was quantified profilometrically. In experiment 1, most NaF toothpastes and 1 F-free formulation reduced tissue loss significantly (between 19 and 42%); the Sn-containing formulations were the most effective (toothpaste and gel 55 and 78% reduction, respectively). In experiment 2, only 4 NaF toothpastes revealed significant effects compared to the F-free control (reduction between 29 and 37%); the F-free special preparations and the Sn toothpaste had no significant effect. The Sn gel (reduction 75%) revealed the best result. Conventional NaF toothpastes reduced the erosive tissue loss, but had limited efficacy regarding the prevention of brushing abrasion. The special formulations were not superior, or were even less effective.

Investigation of the effect of various fluoride compounds and preparations thereof on erosive tissue loss in enamel in vitro.

Metal fluoride preparations are promising in view of protection against dental erosion. The aim of this study was to screen the effect fluoride preparations containing various polyvalent metal cations had on erosion progression under increasingly severe erosive conditions in human enamel in vitro. Specimens were subjected to a cyclic de- and remineralisation procedure. Demineralisation (experiment E1 and E2a: 6 × 2 min/day, experiment E2b: 6 × 5 min/day) was performed with 0.05 M citric acid (pH 2.3). Fluoridation directly followed demineralisation and was reduced stepwise (E1: 6 × 2 min/day, E2a and E2b: 2 × 2 min/day). The test solutions were: ZnF2 (E1), AmF/NaF/CuSO4 (E1), TiF4/AmF/Zn lactate (E1), TiF4 (E1, E2a), TiF4/AmF (E2a), TiF4/AmF/NaF (E2a), TiF4/AmF/ZnF2 (E1, E2a, E2b), AmF/NaF/SnCl2 (2,800 mg/l Sn2+; E1, E2a, E2b), AmF/NaF/SnCl2-1 (700 mg/l Sn2+; E2a, E2b), all 1,500 ppm F–, pH 4.5, and AmF/SnF2 (positive control, pH 4.2, 250 ppm F–; E1, E2a, E2b). In the negative control group, specimens were not fluoridated. Tissue loss was determined by profilometry after the last experimental day. Under mild conditions (E1), tin- and titanium-containing solutions were of marked efficacy and could nearly completely inhibit erosive tissue loss (reduction between 94.2 and 97.5%). With increasingly severe conditions (E2a, E2b), titanium lost its efficacy. Only the highly concentrated tin preparation (2,800 mg/l Sn2+) was able to reduce erosive tissue loss by 93.1%, even under severe conditions (E2b), with less frequent application of the experimental preparations. It should be considered for approaches for a symptomatic therapy of dental erosion.

Effects of toothbrushing force on the mineral content and demineralized organic matrix of eroded dentine

Eroded dentine has a complex histological structure, and its organic fraction becomes increasingly exposed as a result of the continual action of acids. The present study sought to investigate the effects of brushing forces up to 4 N on mineralized and organic dentine fractions. The study was a cyclic demineralization and remineralization experiment (carried out over 9 d). Erosion was performed with HCl (6 x 2 min d-1), pH 1.6. Samples exposed to erosion alone served as controls; test samples were eroded and brushed with a powered toothbrush (2 x 15 s d-1), applying forces of 2, 3, or 4 N. Samples were analysed (using profilometry and longitudinal microradiography) before and after the removal of superficial organic material with collagenase. Randomly selected samples were subjected to scanning electron microscopy. Demineralized organic material was present on all samples regardless of brushing force. Loss values (determined using profilometry) after erosion only, and after brushing with forces of 2, 3, and 4 N, were 11.7 +/- 5.1, 13.6 +/- 11.2, 30.7 +/- 19.0, and 25.5 +/- 20.3, respectively, before treatment with collagenase, and 111.7 +/- 11.6, 122.0 +/- 11.8, 121.9 +/- 15.7, and 123.0 +/- 12.0, respectively, after treatment with collagenase. Microradiography confirmed the results. Significant effects of brushing force were only found on the demineralized organic fraction, and mineral loss was unaffected. The notion that eroded dentine is particularly prone to abrasion should be reconsidered.

Dental Erosions in Subjects Living on a Raw Food Diet

The aim of the study was to investigate the frequency and severity of dental erosions and its association with nutritional and oral hygiene factors in subjects living on a raw food diet. As part of a larger dietary study 130 subjects whose ingestion of raw food was more than 95% of the total food intake were examined. The median duration of the diet was 39 (minimum 17, maximum 418) months. Before the clinical examination, the participants answered questionnaires and recorded their food intake during a 7–day period. Dental erosions were registered using study models. As a control 76 sex– and age–matched patients from our clinic were randomly selected. The raw food diet records showed the median daily frequency of ingesting citrus fruit to be 4.8 (minimum 0.5, maximum 16.1). The median intake of fruit was 62% (minimum 25%, maximum 96%) of the total, corresponding to an average consumption of 9.5 kg of fruit (minimum 1.5, maximum 23.7) per week. Compared to the control group subjects living on a raw food diet had significantly (p≤0.001) more dental erosions. Only 2.3% of the raw food group (13.2% of the controls) had no erosive defects, whereas 37.2% had at least one tooth with a moderate erosion (55.2% of the controls) and 60.5% had at least one tooth with a severe erosion (31.6% of the controls). Within the raw food group no significant correlation was found between nutrition or oral health data and the prevalence of erosions. Nevertheless, the results showed that a raw food diet bears an increased risk of dental erosion compared to conventional nutrition.