Scanning electron microscope and electron microprobe study of reactions of stannous fluoride and stannous chloride with dental enamel

Abstract — Stannous fluoride but not stannous chloride has shown a caries inhibiting effect in animal studies. The effect of aqueous solutions of stannous fluoride and stannous chloride on dental enamel surfaces was investigated by scanning electron microscope and analytical electron microprobe. Some large globules and a continuous layer of small globules were observed after stannous fluoride treatment. The large globules were soluble in both water and alkali, whereas the small ones were only soluble in alkali. Both fluoride and tin were found to be present on the enamel surfaces by the electron microprobe after stannous fluoride treatment. The fluoride could not be detected after immersion in distilled water whereas alkali treatment removed the tin. The large fluoride-containing globules may consist of calcium fluoride as this substance is known to be slightly soluble in water and soluble in alkali. Stannous chloride treatment gave a layer of small tin-containing globules with properties similar to the layer formed on enamel treated with stannous fluoride. It is therefore suggested that the tin-containing layer is not associated with caries protection whereas calcium fluoride-like deposition on the enamel probably is a factor in the caries inhibition caused by stannous fluoride.     

Treatment of dentin with stannous fluoride--SEM and electron microprobe study

The effect of SnF2-treatment of dentin surfaces was investigated by means of scanning electron microscopy (SEM) and electron microprobe analysis. Human dentin was treated with aqueous SnF2 solutions of concentrations varying from 1 to 10%. The treatment periods lasted for 1, 5, 10, or 60 min. Both tin and fluoride were identified on the surfaces. The concentration varied depending on the extensiveness of the treatment. Immersion in 1 M KOH for 15 h removed both tin and fluoride from the surfaces. This reaction was not observed after immersion in H2O for the same time period. Examination of the SnF2-treated dentin surfaces showed a dense layer of globular particles and in addition some larger particles. The dentinal tubules were totally covered even after the treatment with the lowest concentration of SnF2. Deposition of tin- and fluoride-containing globules on dentin surfaces may be of clinical interest. This layer may have importance both for the caries resistance of dentin and for hypersensitivity reactions.     

Effect of fluoride on the rate of dentin apposition and caries progression in young and old Wistar rats

The effect of fluoride in drinking water on the progression of dentinal caries and dentin apposition was studied separately in young and old Wistar rats. The animals were inoculated with Streptococcus sobrinus and fed ad libitum on a 43% sucrose diet and distilled water supplemented with 0, 1, or 19 ppm fluoride. After a 7-wk (young) or 13-wk (adult) cariogenic challenge, the areas of dentinal caries and dentin apposition were quantified after tetracycline staining. Fluoride in the drinking water reduced the progression of dentinal caries and the speed of dentin formation in the young animals but only the progression of dental caries in the adult ones. Both the progression of carious lesions in the dentin and the rate of dentin apposition were 10 times faster during primary dentinogenesis.     

Effect of gels containing stannous fluoride on oral bacteria — an in vitro study

The purposes of this investigation were to evaluate and compare the antimicrobial effect of (1) twelve 0.4 per cent stannous fluoride (SnF2) commercial products and (2) different concentrations of SnF2 (range = 0.02 to 3.28 per cent). The antibacterial inhibitory effect of various SnF2 gels was evaluated as to their effectiveness against oral plaque bacteria including strains of S. mutans, S. sanguis, S. sobrinus, A. viscosus, A. actinomycetemcomitans, and B. intermedius. When twelve different commercial preparations of 0.4 per cent SnF2 were compared for inhibitory effect on plaque bacteria, several of the SnF2 preparations were significantly more effective in inhibiting oral bacteria (p < 0.05). With increasing concentration of SnF2, there was a comparable increase in the inhibitory effect on the oral bacteria tested (r2 ranged from 0.867 to 0.996). SnF2 at a concentration of 0.4 per cent had a similar antibacterial effect to 0.12 per cent chlorhexidine. This in vitro study demonstrated that certain SnF2 products are highly effective in inhibiting the growth of bacteria often found in plaque, and this inhibitory effect is directly related to the concentration of the SnF2.     

Effect of fluoride on caries progression and dentin apposition in rats fed on a cariogenic or non-cariogenic diet

The effect of fluoride in drinking water on the progression of dentinal caries and dentin apposition was studied in Wistar rats. The initiation of enamel caries lesions was first induced for 2 wk with S. sobrinus and a 43% sucrose diet after weaning. Thereafter the animals were fed on either a cariogenic or a non-cariogenic diet and distilled water supplemented with 0, 1, 7 or 19 ppm fluoride. The areas of dentinal caries and dentin apposition were quantified after tetracycline staining. Fluoride reduced dentinal caries progression after the initiation of lesions in the presence of a cariogenic diet at a concentration of 19 ppm F, and without sucrose at 1 ppm F. The effect of fluoride in reducing dentin apposition with a cariogenic diet was dose-dependent, whereas fluoride in non-cariogenic groups had practically no effect on dentin formation. These results suggest that fluoride together with a high concentration of sucrose in the diet might have an odontoblast-mediated effect on the regulation of the progression of dentinal caries.     

Effect of amine fluoride/stannous fluoride toothpaste and mouthrinse on dental plaque accumulation and gingival health

Objective: The aim was to investigate the influence of amine fluoride (AmF)/stannous fluoride (SnF₂) containing toothpaste and mouthrinse on plaque accumulation and gingival health of young adults after 4 weeks use. Subject and methods: Forty‐two young adults (mean age: 28.33 ± 7.19 years) were examined for the Plaque Index (PI; Silness and Löe, 1964 ) and Gingival Index (GI; Löe and Silness, 1963 ) scores, and divided randomly into two groups. Both groups used AmF/SnF₂ containing toothpaste twice a day for 3 min toothbrushing, and one group after toothbrushing rinsed with AmF/SnF₂ containing mouthrinse for 30 s. After 4 weeks the probands were re‐examined. Results: Statistically significant decrease in dental plaque (PI) and gingival (GI) index values were found at the end of the study. The reduction of PI and GI values was significant in all groups but it was higher in the combined (toothpaste + mouthrinsing) group, than using toothpaste only. Conclusion: The regular combined use of AmF/SnF₂ toothpaste and mouthrinse was more effective in the reduction of plaque accumulation and maintenance of gingival health than the toothpaste alone.     

氟对牙本质作用的研究进展

牙齿硬组织主要由釉质和牙本质组成，牙胚发育阶段摄入过量氟对二者均有损害。关于氟对釉质的损伤研究已有较多报道，而有关氢对牙本质损伤的报道则很少。本文就过量氟对牙本质形态结构的影响、对牙本质基质的影响、氟中毒牙本质对黏结治疗的影响和小剂量氟对牙本质的防龋机制作一综述。     

Chemical analysis and scanning electron microscopy of acquired pellicle formed in vivo on stannous fluoride treated enamel

Abstract – Stannous fluoride (SnF₂) has been shown to be an effective caries preventive agent. After topical treatment of enamel surfaces, two reaction products have been demonstrated to precipitate on the surfaces, a larger type of globules, probably a calcium fluoride like product, and a smaller type of globules, probably a tin phosphate. The aim of the present study was to examine the amino acid composition and the formation of the acquired pellicle on SnF₂-treated enamel in vivo. The chemical composition was examined by amino acid analysis of pellicle material collected in vivo from SnF₂-treated enamel surfaces. Pellicle formation was examined by scanning electron microscopy on SnF₂-treated enamel fragments carried in the mouth for 2 h. The results showed that pellicle material was formed in abundant amounts and covered the globular surfaces following the SnF₂ treatment. The chemical analyses showed amino acid profiles with high content of acidic and neutral amino acids. The profiles were different from known amino acid profiles obtained from analyses of pellicle material collected from untreated enamel surfaces.     

������������������ʴ�о���չ

牙齿酸蚀症是一种常见的口腔疾病,随着人们生活水平的提高,其发病率在逐年增长.牙釉质在酸性环境下会发生羟基磷灰石溶解反应,磷酸钙盐被溶出,并扩散至牙齿表面,这个过程称之为脱矿.釉质脱矿一旦发生,大部分不可逆转,常会影响到牙齿的健康和美观.防治牙齿酸蚀成为近几年国内外学者研究的热点,而氟化亚锡对牙齿的保护作用也受到学者们的重视.本文对氟化亚锡防治牙齿酸蚀的机制,应用的局限性和安全性,以及验证其防酸蚀效应的实验影响因素进行综述.     

Effect of stannous fluoride toothpaste on erosion-like lesions: an in vivo study

It has recently been shown that stannous fluoride (SnF(2)), in the form of aqueous solutions and as toothpaste, can reduce the dissolution of enamel in erosive acids in vitro and in situ. The aim of this study was to compare the effect of toothpastes containing SnF(2) or NaF on enamel dissolution using an in vivo model. Four healthy anterior teeth in each subject (n = 20) were exposed to diluted citric acid (100 mmol l(-1) or 10 mmol l(-1)) applied using a peristaltic pump (5 ml @7 ml min(-1)) and the acid was collected in a test tube before and after application of the respective toothpastes (etch I and etch II). Toothpaste was applied to the labial surfaces with a soft brush (four applications, each of 1-min duration), with gentle water rinsing between applications. Each subject had one pair of teeth treated with each of the test toothpastes. Enamel dissolution was examined by assessment of calcium content in the citric acid applied before and after the treatment with toothpaste. The results indicate that the SnF(2) toothpaste markedly reduced the dissolution of teeth in vivo (etch II < etch I), whereas the NaF toothpaste provided no protection (etch II > etch I). Toothpaste appears to be an acceptable vehicle for SnF(2) and maintains the dissolution-reducing effect exhibited by aqueous solutions of this fluoride salt.     

A review of the effects of stannous fluoride on gingivitis

AIM: To review the literature on the effects of stannous fluoride on gingivitis. MATERIAL AND METHODS: The Medline and cochrane central register of controlled trials were searched up to August 2005 to identify appropriate studies. The primary outcome measure was gingivitis. RESULTS: Independent screening of titles and abstracts of 542 papers resulted in 36 publications (inter-reviewer ê score of 0.76), out of which 15 papers finally fulfilled the criteria of eligibility. For SnF(2)dentifrices, a statistically significant reduction in gingivitis was noted in comparison with control (weighted mean difference (WMD) of 0.15 (gingival index) and 0.21 (gingivitis severity index) (test for heterogeneity p<0.00001, I(2)=91.1% and p=0.03, I(2)=80.1%, respectively)). With regard to plaque reduction inconsistent results existed. On using the plaque index no differences were found, whereas meta-analysis of the Turesky index provided a WMD of 0.31 (p=0.01, test for heterogeneity p<0.0001, I(2)=91.7%). Because of insufficient data, a meta-analysis for SnF(2)mouth rinse and dentifrice/mouthrinse formulations was not performed. CONCLUSIONS: The use of SnF(2) dentifrices results in gingivitis and plaque reduction when compared with a conventional dentifrice. The precise magnitude of this effect was difficult to assess because of a high level of heterogeneity in study outcomes.     

Scanning electron microscope and electron microprobe study of reactions of stannous fluoride and stannous chloride with dental enamel

Stannous fluoride but not stannous chloride has shown a caries inhibiting effect in animal studies. The effect of aqueous solutions of stannous fluoride and stannous chloride on dental enamel surfaces was investigated by scanning electron microscope and analytical electron microprobe. Some large globules and a continuous layer of small globules were observed after stannous fluoride treatment. The large globules were soluble in both water and alkali, whereas the small ones were only soluble in alkali. Both fluoride and tin were found to be present on the enamel surfaces by the electron microprobe after stannous fluoride treatment. The fluoride could not be detected after immersion in distilled water whereas alkali treatment removed the tin. The large fluoride-containing globules may consist of calcium fluoride as this substance is known to be slightly soluble in water and soluble in alkali. Stannous chloride treatment gave a layer of small tin-containing globules with properties similar to the layer formed on enamel treated with stannous fluoride. It is therefore suggested that the tin-containing layer is not associated with caries protection whereas calcium fluoride-like deposition on the enamel probably is a factor in the caries inhibition caused by stannous fluoride.     

An alternate technique of care using silver fluoride followed by stannous fluoride in the management of root caries in aged care

An alternate technique of care to prevent, arrest and manage root caries using aqueous silver fluoride followed by stannous fluoride (AgF+SnF₂) in aged care is demonstrated by three case studies. With increasing age, the inability to maintain ones own oral care from dementia, illness or frailty and polypharmacy induced salivary gland hypofunction will result in dental caries becoming a progessively greater burden for the elderly. Future generations of elders will live longer and need to maintain many more teeth longer than earlier generations. Both silver diamine fluoride (SDF)and AgF+SnF₂ arrest and prevent caries and are easy to use in residential aged care facilities. Clinical differences between SDF and AgF+SnF₂ are discussed. However, in aged care, AgF+SnF₂ may offer advantages over SDF. AgF+SnF₂ used to arrest and prevent caries in children can be modified to provide effective but minimally invasive care for an ageing and frail population. These techniques are rapid, inexpensive and nonthreatening suited to treat frail elders, dementia patients exhibiting challenging behaviours and patients with multiple rapidly progressing decay. Silver fluoride, applied before placing glass‐ionomer cement (GIC) restorations is an important adjunct to the atraumatic restorative technique and may retard caries reactivation more than GIC used alone.     

Comparative antiplaque effectiveness of an essential oil and an amine fluoride/stannous fluoride mouthrinse

The adjunctive use of antimicrobial mouthrinses to help control supragingival plaque and gingivitis has been shown to contribute significantly to patients' daily oral hygiene regimens. This controlled clinical study used an observer-blind, randomized, cross-over design in a 4-day plaque regrowth model to determine the relative efficacies of an essential oil-containing mouthrinse (Listerine Antiseptic) and an amine fluoride/stannous fluoride-containing mouthrinse (Meridol) in inhibiting the development of supragingival plaque. A 0.1% chlorhexidine mouthrinse (Chlorhexamed-Fluid) was used as a positive control, and a 5% hydroalcohol solution was used as a negative control. Dosing for each of the test mouthrinses was based on the manufacturers' label directions. Because the volume and rinse time for each of the test mouthrinses were different, each test mouthrinse had its own negative control group. On day 1 of each test period, subjects received an oral soft and hard tissue examination and a dental prophylaxis to remove all plaque, calculus, and extrinsic stain. Starting the same day, subjects refrained from all mechanical oral hygiene procedures for the next 4 days and rinsed 2x daily under supervision with their randomly-assigned mouthrinse. On day 5, each subject received a plaque assessment as well as an oral examination to assess side effects. Each test period was separated by a 2-week washout period. 23 volunteers with a median age of 26 years completed the study. Compared to the respective placebos, the median percent plaque reductions at 5 days were 23.0%, 12.2%, and 38.2% for the essential oil, amine/stannous fluoride, and chlorhexidine rinses, respectively. The plaque reductions seen in the essential oil and chlorhexidine rinse groups were statistically significant (p < 0.001), while the plaque reduction in the amine/stannous fluoride rinse group was not statistically significant (p > 0.05). Additionally, the essential oil rinse was significantly more effective (p < 0.001) than the amine/stannous fluoride rinse in inhibiting plaque accumulation in this clinical model.     

Inhibition of dentin matrix‐bound cysteine cathepsins by potassium fluoride

Matrix metalloproteinases (MMPs) and cysteine cathepsins (CCs) can break down unprotected type I collagen fibrils in dentin matrix. This study investigated the use of potassium fluoride (KF) as a potential inhibitor of MMPs and CCs in dentin. Demineralized dentin beams were divided into groups (n = 10 in each group) and incubated in artificial saliva (AS, control), either alone or with one of seven concentrations of KF (6–238 mM fluoride) for 1, 7, and 21 d. After 21 d, all groups were further aged in AS for 6 months. Total MMP activity was screened using the colorimetric MMP assay. The activities of MMP‐2 and MMP‐9 were investigated using gelatin zymography. At the end of each incubation, changes in loss of dry mass and CC‐mediated or total dissolution of collagen peptides were measured via precision weighing, C‐terminal crosslinked telopeptide of type I collagen (CTX), and hydroxyproline (HYP) assays. The beams were examined using scanning electron microscopy. After 21 d, total MMP activities, dry mass loss, and CTX release for the groups exposed to 179 and 238 mM fluoride were significantly lower compared with the control group. After 6 months, all groups showed similar total MMP activity, dry mass loss, and HYP release, and CTX levels were significantly lower when the fluoride concentration was ≥24 mM. Calcium fluoride (CaF₂)‐like precipitates were observed over the beams. In summary, KF significantly inhibited the catalytic activity of dentin matrix‐bound CCs but did not seem to be effective for MMP‐mediated activity.     

Short-term bactericidal activity of chlorhexidine gel, stannous fluoride gel and amine fluoride gel tested in periodontal pockets

The short-term bactericidal effect of 2% chlorhexidine gel, 4% stannous fluoride gel or amine fluoride gel containing 1.25% fluoride on the subgingival microflora was determined in 40 periodontal pockets of 10 patients. The antimicrobial gels or placebo gel were applied in 5-9 mm deep periodontal pockets 3 times within 10 min. Before and 30 min after the applications, samples were taken of the subgingival microflora for determination of the total number of bacteria as well as the number of black pigmented Bacteroides. Reductions of the total number of bacteria were found in all test groups. The reductions found in the pockets treated with chlorhexidine gel or stannous fluoride gel were significantly greater than the reduction found in the pockets treated with a placebo gel. A significant reduction of black-pigmented Bacteroides was found after treatment with chlorhexidine gel or amine fluoride gel. It is concluded that 2% chlorhexidine gel or 4% stannous fluoride gel has a more than 99% reduction effect on the microflora of periodontal pockets within 30 min after application.     

Indirect caries‐preventive effect of silver diamine fluoride on adjacent dental substrate: A single‐section demineralization study

This study assessed the indirect effect of 38% silver diamine fluoride (SDF) on demineralization of adjacent untreated sound and pre‐demineralized enamel and dentine using a single‐section model for digital transverse microradiography (TMR‐D). Forty‐eight bovine dentine single sections were demineralized, stratified (n = 12) according to integrated mineral loss (ΔZ), and treated with SDF or deionized water (DIW). Each “treated dentine” section was attached between untreated sound and pre‐demineralized enamel or dentine and then subjected to demineralization. ΔZ and lesion depths (LD) of all specimens at baseline, 24 and 48 h demineralization, and after treatment of “treated dentine” were quantified using TMR‐D. Fluoride in the demineralization solution of SDF clusters was determined using an ion‐selective electrode. ΔZ and LD of sound and ΔZ of pre‐demineralized enamel adjacent to SDF‐treated dentine did not increase over time. All untreated dentine demineralized significantly; however, ΔZ of sound dentine adjacent to SDF‐treated specimen was still significantly lower than control. SDF‐treated dentine remineralized and released fluoride even after 48 h. Consistent with clinical findings, when applied only to demineralized teeth in this chemical model, 38% SDF completely inhibited demineralization in adjacent untreated sound enamel. Demineralization prevention was observed to a lesser extent in adjacent pre‐demineralized enamel but not in dentine.     

The effect of a dentifrice and mouth rinse combination containing amine fluoride/stannous fluoride on plaque and gingivitis: a 6-month field study

AIM: To examine the effect of amine fluoride/stannous fluoride (AmF/SnF(2))-containing dentifrice and mouth rinse on plaque formation and gingivitis as compared with habitual oral hygiene procedures with a regular sodium fluoride (NaF) dentifrice. MATERIAL AND METHODS: In total, 22 general practices participated in this research project. The participants (N=281) were randomly assigned into two groups: the test group received an AmF/SnF(2) dentifrice-mouth rinse combination and the control group received a NaF-containing dentifrice. The patients were requested to brush twice daily for approximately 2 min. The subjects of the test group had to rinse additionally in the evening for 30 s with 10 ml of the mouth rinse. RESULTS: Both groups started with comparable scores of plaque, bleeding and staining. At 6 months, the plaque scores were 0.95 for the AmF/SnF(2) group and 0.99 for the NaF group (decrease of 16% and 10%, respectively). Bleeding scores, although significantly different from baseline, did not show differences between the two regimes. At the end of the experimental period, the overall staining was more pronounced in the AmF/SnF(2) group (41%) than the NaF group (26%). Both plaque reduction and increase in staining seemed to be correlated to the amount of mouth rinse used in the test group. CONCLUSION: In instruction-resistant patients recruited from dental practices, the combined use of AmF/SnF(2) did not decrease gingivitis at a significant level in comparison with the regular regime of two times daily brushing with an NaF-containing dentifrice. However, the above-mentioned combination resulted in greater plaque reduction than that observed with the use of the conventional dentifrice. When used according to the manufacturer's instructions, this effect on plaque scores was more pronounced.     

Evaluation of stannous fluoride and chlorhexidine sprays on plaque and gingivitis in handicapped children

The objective of this study was to evaluate the effect of twice-daily oral sprays of 2 ml chlorhexidine (0.2%) and 2 ml stannous fluoride (0.2%) as the sole oral hygiene measure on plaque and gingivitis in handicapped children. 52 institutionalized mentally handicapped individuals (aged 10-26 years) were divided into 4 groups to participate in a 9-week, double-blind, randomized clinically controlled trial, which included a cross-over. For the first 3 weeks, groups 3 and 2 had their mouths sprayed with chlorhexidine and stannous fluoride, respectively. Following a 3-week wash-out interval, groups 1 and 4 were sprayed with chlorhexidine and stannous fluoride, respectively. The alternate groups received a placebo, water. Plaque (PI) and gingival indices (GI) were recorded. Subgingival plaque samples were collected and counts of spirochaetes, motile rods and cocci were taken using darkfield microscopy. By the 9th week of trial, the PI and GI were reduced by 48% and 52% for the stannous fluoride group. In the chlorhexidine group, reductions of 75% (PI) and 78% (GI) were achieved. Pair-wise comparisons of placebo, stannous fluoride and chlorhexidine using the U-test of Mann-Whitney revealed significant (p less than 0.05) differences for both PI and GI scores in the placebo/stannous fluoride and placebo/chlorhexidine pair by the 9th week of the trial. In the stannous fluoride/chlorhexidine pair, only the PI was significantly reduced for those on chlorhexidine. Coccoid cells were more dominant at sites with low PI and GI scores (stannous fluoride and chlorhexidine groups), while spirochaetes and motile rods were more frequent at sites with high PI and GI scores (placebo group).