Effects of various fluoride solutions on enamel erosion in vitro

The objective of this in vitro study was to investigate the effect of different fluoride solutions on enamel erosion. Human enamel specimens were pretreated with 1 of 10 different fluoride solutions (n = 20): TiF(4), NaF, AmF, ZnF(2), or SnF(2), each at native pH (pH range: 1.2-7.8) or buffered pH (pH = 4). The control group samples received no fluoride pretreatment. All samples were then eroded by citric acid (pH 2.6) for 6 x 1 min daily over 5 days. Between the erosive cycles, the samples were stored in artificial saliva. Erosion effects were investigated by surface profilometry (n = 10), scanning electron microscopy (n = 4), and energy-dispersive X-ray spectroscopy (n = 6) after fluoride pretreatment and after erosion. To test the effects of pH only, additional experiments were carried out with fluoride-free solutions at similar pH to that of fluoride solutions. In general, AmF solution was more effective in protecting enamel erosion compared to all other fluoride agents. However, the application of native TiF(4), native and buffered SnF(2), and native and buffered AmF solutions also resulted in significantly less enamel loss compared to the control group. A Ti-rich coating was formed after application of native TiF(4), but partially dissolved due to erosive attack. Samples pretreated with SnF(2) showed a significant increase in surface tin content. Surface fluoride concentration was significantly increased by native TiF(4), native and buffered AmF, buffered ZnF(2), and buffered NaF application. Under the current experimental setting, the fluoride agents at lower pH had better protective potential. Highly concentrated TiF(4), AmF, and SnF(2) solution was effective in inhibiting erosion of enamel

Deposition of fluoride on enamel surfaces released from varnishes is limited to vicinity of fluoridation site

The aim of the in-situ study was to determine fluoride uptake in non-fluoridated, demineralized enamel after application of fluoride varnishes on enamel samples located at various distances from the non-fluoridated samples. All enamel samples used were demineralized with acidic hydroxyethylcellulose before the experiment. Intra-oral appliances were worn by ten volunteers in three series: (1, Mirafluorid, 0.15% F; 2, Duraphat, 2.3% F and 3, unfluoridated controls) of 6days each. Each two enamel samples were prepared from 30 bovine incisors. One sample was used for the determination of baseline fluoride content (BFC); the other was treated according to the respective series and fixed in the intra-oral appliance for 6days. Additionally, from 120 incisors, each four enamel samples were prepared (one for BFC). Three samples (a-c) were placed into each appliance at different sites: (a) directly neighboured to the fluoridated specimen (=next), (b) at 1-cm distance (=1cm) and (c) in the opposite buccal aspect of the appliance (=opposite). At these sites, new unfluoridated samples were placed at days 1, 3 and 5, which were left in place for 1day. The volunteers brushed their teeth and the samples with fluoridated toothpaste twice per day. Both the KOH-soluble and structurally bound fluoride were determined in all samples to determine fluoride uptake and were statistically analyzed. One day, after fluoridation with Duraphat, KOH-soluble fluoride uptake in specimen a (=next) was significantly higher compared to the corresponding samples of both the control and Mirafluorid series, which in turn were not significantly different from each other. At all other sites and time points, fluoride uptake in the enamel samples were not different from controls for both fluoride varnishes. Within the first day after application, intra-oral-fluoride release from the tested fluoride varnish Duraphat leads to KOH-soluble fluoride uptake only in enamel samples located in close vicinity to the fluoridation sit

Deposition of fluoride on enamel surfaces released from varnishes is limited to vicinity of fluoridation site

The aim of the in-situ study was to determine fluoride uptake in non-fluoridated, demineralized enamel after application of fluoride varnishes on enamel samples located at various distances from the non-fluoridated samples. All enamel samples used were demineralized with acidic hydroxyethylcellulose before the experiment. Intra-oral appliances were worn by ten volunteers in three series: (1, Mirafluorid, 0.15% F; 2, Duraphat, 2.3% F and 3, unfluoridated controls) of 6 days each. Each two enamel samples were prepared from 30 bovine incisors. One sample was used for the determination of baseline fluoride content (BFC); the other was treated according to the respective series and fixed in the intra-oral appliance for 6 days. Additionally, from 120 incisors, each four enamel samples were prepared (one for BFC). Three samples (a–c) were placed into each appliance at different sites: (a) directly neighboured to the fluoridated specimen (=next), (b) at 1-cm distance (=1 cm) and (c) in the opposite buccal aspect of the appliance (=opposite). At these sites, new unfluoridated samples were placed at days 1, 3 and 5, which were left in place for 1 day. The volunteers brushed their teeth and the samples with fluoridated toothpaste twice per day. Both the KOH-soluble and structurally bound fluoride were determined in all samples to determine fluoride uptake and were statistically analyzed. One day, after fluoridation with Duraphat, KOH-soluble fluoride uptake in specimen a (=next) was significantly higher compared to the corresponding samples of both the control and Mirafluorid series, which in turn were not significantly different from each other. At all other sites and time points, fluoride uptake in the enamel samples were not different from controls for both fluoride varnishes. Within the first day after application, intra-oral-fluoride release from the tested fluoride varnish Duraphat leads to KOH-soluble fluoride uptake only in enamel samples located in close vicinity to the fluoridation site

Fluorescence-aided caries excavation (FACE), caries detector, and conventional caries excavation in primary teeth

PURPOSE: The purpose of this paper was to compare the ability of fluorescence-aided caries excavation (FACE) to remove infected dentin in primary teeth with that of conventional methods. METHODS: Sixty-six extracted carious primary teeth were divided according to lesion size into 3 groups of 22 teeth. Caries excavation was carried out with a slow-speed handpiece and round burs for all groups. In the first group, caries was excavated conventionally using visual tactile criteria. In the second group, a caries detector dye was used to detect carious dentin. In the FACE group, cavities were excited with violet light (370-420 nm) and observed through a 530 nm highpass filter. Orange-red fluorescing areas were removed. Undecalcified thin slices were prepared, stained with Giemsa, and examined for presence of infected dentin using light microscopy. Four samples were lost during processing. RESULTS: Histology showed infected dentin in significantly less FACE samples (3 of 22) compared to conventional excavation (9 of 20; P=.03), but not significantly less compared to caries detector (5 of 20; P=.35). CONCLUSIONS: Within the limitations of this in vitro study, it can be concluded that fluorescence-aided caries excavation is more effective than conventional excavation in removal of infected primary dentin

Repair of silorane composite - using the same substrate or a methacrylate-based composite?

OBJECTIVE: The study aimed to analyze the shear bond strength of aged silorane composite repaired with the same substrate or a conventional methacrylate-based composite after different mechanical and adhesive surface treatments. METHODS: Silorane composite specimens were aged by thermal cycling (5000 cycles, 5-55°C) and randomly assigned to different surface treatments (each group n=16): diamond bur abrasion, aluminum oxide sandblasting, silica coating, or hydrofluoric acid etching. Then, an adhesive system corresponding to the repair composite or a combination of silane agent and the respective adhesive was applied. Silorane composite or a nanofiller composite were adhered onto the conditioned surfaces. In the control group (n=16), silorane composite was adhered to fresh substrate (incremental build up). After further thermal cycling, shear bond strength was tested and failure modes were assessed. Data were analyzed by ANOVA/post hoc tests, Weibull statistics and Chi(2)-test (p≤0.05). RESULTS: Incremental shear bond strength (control group: 21.0±10.5MPa) was achieved by all groups except those etched with hydrofluoric acid or samples abraded with diamond bur and repaired with the nanofiller composite without silane application. Generally, the application of the silane agent improved repair bond strength of the nanofiller but not of the silorane composite. Cohesive failure was observed more frequently than adhesive failure when the silane agent was applied or when silorane composite was used for repair. SIGNIFICANCE: Silorane composite can be repaired with either the same substrate or a methacrylate-based nanofiller composite but requires mechanical surface treatment and - in case of the methacrylate-based composite - silanization prior to adhesive application

Schmelz-Fluoridaufnahme nach Fluoridierung und Fluoridfällung

This study is on fluoride uptake into enamel following fluoride precipitation with calcium hydroxide. Five specimens each from 12 bovine incisors were polished, covered with a salivary pellicle, and distributed into five groups (n=12). A fluoride solution (43,500 ppm F from magnesiumfluorosilicate, copper-(II)-fluorosilicate and sodium-fluoride, pH 2; Tiefenfluorid Touchierlösung, Humanchemie) and Ca(OH)2-solution (Tiefenfluorid Nachtouchierlösung) were applied subsequently in group TN. "Touchierlosung" only was used in group T, sodium-fluoride (43,500 ppm F, pH 2) in group NaF, and aminefluoride (Elmex fluid, 10,000 ppm F, pH 4) in group EF. No fluoride was used in group NK (negative control). Following rinsing and 24 h storage in artificial saliva surface KOH-soluble fluoride content (KOHF), and structurally bound fluoride content (SBF) from three layers (0-33, 33-66 and 66-99 pm) was determined by fluoride electrode procedures. KOHF (median in microg/cm2) of NK was below the lower limit of quantification of the fluoride electrode. The other group values were significantly higher (Mann-Whitney test, p < or = 0.05). TN (1.6), T (1.4) and NaF (1.1) did not differ significantly. EF (0.6) was significantly smaller than TN and T but not smaller than NaF. SBF (0-33, 33-66, 66-99 pm; median in microg/cm3) of TN (445, 341, 275), T (644, 481, 360), NaF (804, 480, 307) and EF (449, 346, 280) did not differ significantly but, with the exception of TN, were significantly higher as compared to NK. A precipitation reaction with Ca(OH)2 following fluoridation did not increase enamel fluoride uptake

Prevention of erosion and abrasion by a high fluoride concentration gel applied at high frequencies

The aim of this study was to determine maximum attainable protection of enamel from erosion and erosion abrasion using a highly fluoridated gel with and without additional fluoride from toothpaste. Thirty-six bovine enamel specimens were subjected to six erosive attacks per day (1% citric acid with pH 2.3 for 30 s), while the rest of the day the specimens were in artificial saliva. There were four treatment groups (9 specimens in each group): fluoride-free toothpaste/saliva slurry twice daily (group T0), fluoride-containing toothpaste/saliva slurry twice daily using 1,250 ppm F toothpaste (group TF), fluoride-containing toothpaste/saliva slurry twice per day plus application of a highly fluoridated gel (12,500 ppm F) twice a day for 120 s (group 2F) and a group with gel application 8 times a day (group 8F). Additionally, half of each specimen in all groups was subjected to brushing abrasion during application of the toothpaste/saliva slurry. Brushing abrasion alone led to no observable enamel loss measured with profilometry. After 14 days of cycling of erosion without toothbrushing abrasion, high-fluoride gel application 2 or 8 times daily showed significantly less enamel loss (median 24/19 μm) than with toothpaste with or without fluoride (41/45 μm). After 14 days of cycling of erosion and toothbrushing abrasion, gel application 2 or 8 times daily (33/29 μm) showed significantly less enamel loss than toothpaste with or without fluoride (57/62 μm). We conclude that a highly fluoridated acidic gel is able to protect enamel from erosion and toothbrushing abrasion while fluoridated tooth paste provides little protection

Subjectivity and examiner experience in diagnosis of residual caries--an in vitro study

The aim was to evaluate subjectivity (using inter- and intraexaminer repeatability), the effect of examiner experience, and residual caries diagnostic accuracy with visual tactile (VT) criteria and using a caries disclosing agent (CD). Thirty teeth with occlusal caries were excavated by a single operator not involved in the diagnostic part of the study. A test area was marked in each cavity. Four dentists with more than five and five dentists with less than five years' experience rated the marked area twice (a week apart) using VT criteria. A week later, the samples were stained using Caries Detector. The same examiners rated the presence or absence of stain in the marked area twice (a week apart). Undecalcified thin slices were examined for bacteria using light microscopy. Overall kappa for inter-examiner repeatability was higher for CD (0.45) than VT (0.31). In the less experienced group the kappa value was higher for CD (0.41) than for VT (0.23). In the experienced group kappa was lower for CD (0.43) than for VT (0.46). Median kappa for intra-examiner repeatability was higher for caries detector (0.77, 0.53) compared to visual tactile (0.52, 0.34) for the more and less experienced examiners respectively. There was no significant difference between the experienced and the inexperienced group in combined sensitivity and specificity (mean) for VT (0.52, 0.53) or CD (0.60, 0.58). In conclusion: VT was more subjective than CD, except for experienced examiners who had a higher inter-examiner repeatability for VT than CD. Diagnostic accuracy for residual caries does not increase with experience