Recent Development of Active Ingredients in Mouthwashes and Toothpastes for Periodontal Diseases

Periodontal diseases like gingivitis and periodontitis are primarily caused by dental plaque. Several antiplaque and anti-microbial agents have been successfully incorporated into toothpastes and mouthwashes to control plaque biofilms and to prevent and treat gingivitis and periodontitis. The aim of this article was to review recent developments in the antiplaque, anti-gingivitis, and anti-periodontitis properties of some common compounds in toothpastes and mouthwashes by evaluating basic and clinical studies, especially the ones published in the past five years. The common active ingredients in toothpastes and mouthwashes included in this review are chlorhexidine, cetylpyridinium chloride, sodium fluoride, stannous fluoride, stannous chloride, zinc oxide, zinc chloride, and two herbs—licorice and curcumin. We believe this comprehensive review will provide useful up-to-date information for dental care professionals and the general public regarding the major oral care products on the market that are in daily use.

Physical and chemical characterization of the surface layers formed on dentin following treatment with an experimental anhydrous stannous fluoride dentifrice

PURPOSE

To characterize, in vitro, the mode of action of stannous fluoride containing formulations in occluding dentin tubules, by means of high resolution microscopy techniques.

METHODS

Focused ion beam scanning electron microscopy (FIB SEM) was used to site-specifically prepare cross sections for SEM and TEM imaging and analysis of dentin samples treated with either a stannous fluoride dispersion in glycerol or an experimental stannous fluoride dentifrice.

RESULTS

An experimental stannous fluoride dentifrice formed a protective layer over the dentin surface and occluded dentin tubules. Additional supporting data derived from a stannous fluoride dispersion in glycerol suggest that stannous fluoride is a key component of this occluding system. Multiple SEM images obtained from sequential FIB cross-sections were reconstructed into 3-dimensional tomograms that showed a formed layer and tubule occlusion. Sections thinned by FIB techniques were observed by transmission electron microscopy (TEM) and related methods and showed that the coating, which was up to 3 microm-thick, consisted of a tin containing precipitate. Chemical analysis by energy dispersive x-ray spectroscopy (EDS) mapping that used scanning TEM (STEM) methods showed interdiffusion of tin up to 200 nm into the dentin structure.

Stannous fluoride dentifrices

Stannous fluoride has a long history of use in the improvement of oral health, and was the fluoride source first proven to provide anti-caries benefits when delivered from a dentrifrice formulation. This paper provides an account of the early use of stannous fluoride, primarily for an anti-caries benefit, and the subsequent attempts to formulate stannous fluoride into stable formulations where additional benefits of the stannous cation can be realized.

A randomized clinical study to assess the extrinsic staining profiles of stannous- and triclosan-containing dentifrices

PURPOSE

To evaluate the extrinsic stain profiles of two experimental stannous-containing dentifrice prototypes compared to two marketed control dentifrices.

METHODS

This was a 5-week, randomized, four-treatment, parallel group, double-blind clinical trial of healthy adults. Following a baseline Lobene Stain Index evaluation, subjects received a prophylaxis limited to the 12 anterior teeth to remove surface stain and calculus. They were randomly assigned based on stain scores to one of the four treatment groups: one of two experimental stannous-containing sodium fluoride dentifrices; a non-staining marketed triclosan dentifrice (Colgate Total); or a 0.454% stannous fluoride dentifrice (Crest Gum Care). Subjects brushed for 1 minute twice daily at home with their assigned dentifrice. Stain examinations were repeated at Week 3 and Week 5 to assess treatment differences.

RESULTS

For the 96 subjects completing the study, Lobene stain composite mean scores--as well as extent (area) and intensity average scores--were significantly lower in the two experimental stannous-containing dentifrice groups and the Colgate Total group when compared to Crest Gum Care (P < 0.0001) at both Weeks 3 and 5. There were no statistically significant differences (P > 0.145) in stain accumulation at either time point between the experimental stannous groups and the Colgate Total group by any Lobene stain measure (composite, extent, intensity). All dentifrices were well-tolerated.

The anti-plaque efficacy of a novel stannous-containing sodium fluoride dentifrice: a randomized and controlled clinical trial

PURPOSE

To evaluate the anti-plaque efficacy of a novel stannous-containing sodium fluoride dentifrice compared to a negative control regular anti-caries dentifrice and a positive control marketed triclosan-containing dentifrice.

METHODS

This was a randomized and controlled, single-center, double-blind, three-treatment, three-period, crossover clinical trial in generally healthy adults. A prophylaxis was followed by three 4-day treatment periods of limited brushing, each separated by an approximate 7-day washout phase. Subjects used the test dentifrice on Days 0-3 of each period according to their randomly assigned sequence; either Crest Cavity Protection (negative control); an experimental stannous-containing sodium fluoride dentifrice; or a marketed triclosan positive control (Colgate Total). A dental polishing was given at Day 0 of each treatment period, and subjects brushed the lingual surfaces only and then swished the entire dentition with a dentifrice slurry twice daily under supervision through Day 3. At baseline and Day 4 of each treatment period, plaque levels were assessed via the Turesky Modification of the Quigley-Hein Plaque Index (TMQHPI).

RESULTS

Twenty-eight fully evaluable subjects completed the trial. Both the experimental and positive control dentifrices provided significantly lower mean whole mouth TMQHPI plaque scores after treatment compared to the negative control: 11.4% lower for the experimental stannous-containing dentifrice and 8.4% for Colgate Total (P< 0.0001). The experimental stannous-containing dentifrice group resulted in directionally lower whole mouth plaque scores when compared to Colgate Total (P= 0.07). The experimental stannous-containing dentifrice had significantly lower mean plaque scores post-treatment at lingual sites compared with Total (P= 0.0355). All dentifrices were well-tolerated.

Innovations in global dentifrice technology: an advanced stannous-containing sodium fluoride dentifrice

PURPOSE

Despite oral health improvements in many geographies, the prevalence of oral concerns, including caries, gingivitis, dentin hypersensitivity, breath malodor, calculus, and extrinsic staining remains unacceptably high across the globe. Dentifrice offers a convenient and accessible vehicle to deliver ingredients--such as antimicrobials, fluoride, and esthetic-enhancing agents--to treat a broad range of common oral conditions. Recently, a novel stannous-containing sodium fluoride (1450 ppm F-) dentifrice was introduced that has been tested in the lab and/or clinically in diverse geographic regions for its impact on major oral conditions.

METHODS

This next-generation dentifrice, marketed as Crest Pro-Health in China and blend-a-med Pro-Expert in parts of Europe, has been extensively clinically tested in the lab and/or clinically on multiple continents in a broad range of subject populations with varying levels of disease and/or cosmetic concerns. This special issue features a few of the many laboratory and clinical investigations conducted on this formulation.

RESULTS

The findings reported here demonstrate the product's anticaries potential as well as its ability to reduce plaque, improve dentin hypersensitivity, inhibit extrinsic stain, and improve breath malodor.

Breath malodor reduction with use of a stannous-containing sodium fluoride dentifrice: a meta-analysis of four randomized and controlled clinical trials

PURPOSE

To determine the effectiveness of a novel stannous-containing sodium fluoride dentifrice in reducing malodor-causing volatile sulfur compound (VSC) levels versus a standard marketed fluoride (negative control) anti-caries dentifrice using pooled data from independent clinical trials.

METHODS

Four randomized and controlled, evaluator-blinded, 3- or 4-period, 2-treatment crossover clinical studies were conducted at four separate centers in Asia and the United States in subjects with a baseline VSC score of > 100 ppb. Following a week-long acclimation period, subjects were randomly assigned to a treatment sequence specifying the order of use of a stannous-containing sodium fluoride dentifrice and a negative control dentifrice (Crest Cavity Protection). VSC levels were assessed at four time points using a Halimeter during each treatment period: (1) baseline prior to treatment; (2) 3-4 hours after baseline and a single brushing; (3) 24 hours post-baseline and after two total brushings ("overnight"/"morning breath"); and (4) 27-28 hours post-baseline following three total product uses. Brushing instructions were standardized and required two minutes of timed toothbrushing with the assigned dentifrice. Washout periods of at least 2 days separated the treatment periods.

RESULTS

A total of 100 subjects were included in the meta-analysis. The stannous-containing dentifrice showed statistically significantly greater breath benefits via VSC reduction compared to the negative control dentifrice (P < 0.047) at all three time points. The stannous-containing dentifrice provided increasingly greater superior relative breath protection benefits of 7.7% at Hour 3-4 post-baseline, 10.6% after 24 hours ("overnight"/"morning breath"), and 24.5% at Hour 27-28. Similar malodor reduction benefits in favor of the stannous-containing dentifrice relative to the negative control were observed for each individual study.

The desensitizing efficacy of a novel stannous-containing sodium fluoride dentifrice: an 8-week randomized and controlled clinical trial

PURPOSE

To assess the efficacy of a novel stannous-containing dentifrice in the reduction of dentin hypersensitivity when compared to a marketed positive control dentifrice.

METHODS

An 8-week, single-center, randomized, parallel group, two-treatment, double-blind clinical study was conducted in a generally healthy adult population with moderate thermal and tactile dentin hypersensitivity. A total of 60 adults were enrolled into the study. Participants were stratified at baseline by age, gender, and cold air sensitivity scores, and randomly assigned to either an experimental stannous-containing sodium fluoride dentifrice or a marketed potassium nitrate positive control. Brushing was supervised on site after baseline and Week 4 examinations. All other product usage was unsupervised. Subjects brushed 2 minutes twice daily. At baseline, Week 4 and Week 8, efficacy outcomes were assessed for tactile sensitivity via the Yeaple Probe, and for thermal sensitivity with air-blast/SchiffAir Index.

RESULTS

Fifty-eight subjects completed all evaluations. Both the experimental stannous-containing and positive control dentifrices provided significant (P< 0.05) reductions in both tactile and thermal dentin hypersensitivity compared to baseline at both Weeks 4 and 8. There were no significant differences in Yeaple Probe or Schiff Air Index results between the dentifrices with either efficacy measurement at Week 4 and Week 8 (P > or = 0.5375).

Anticaries potential of a stabilized stannous-containing sodium fluoride dentifrice

PURPOSE

To evaluate the anticaries potential of a stabilized stannous-containing sodium fluoride dentifrice relative to appropriate control products.

METHODS

A series of in vitro studies was conducted using the following standard anticaries efficacy measures: (1) fluoride uptake; (2) pH cycling remineralization/inhibition of demineralization; and (3) surface microhardness. In each study, the stannous-containing sodium fluoride test dentifrice (1450 ppm F) was compared to a negative control dentifrice (0 ppm F) and a positive control fluoride dentifrice (either 1100 ppm F or 1450 ppm F).

RESULTS

Fluoride uptake: The mean fluoride uptake from both the test dentifrice and the positive control dentifrice was significantly greater than the negative control. There was no statistically significant difference between the two fluoride dentifrices, although the test dentifrice was directionally higher. pH cycling: The remineralization measured with the test dentifrice was directionally higher though not significantly different from the positive control dentifrice. Remineralization by both fluoride-containing dentifrices was significantly greater versus the negative control. Surface microhardness: The percent increase in surface microhardness measured on enamel surfaces after treatments with the test dentifrice was found to be significantly higher than that measured for the positive control and the negative control.

Evaluation of the antimicrobial activity of dentifrices on human oral bacteria

OBJECTIVE

In vitro testing of antimicrobial agents is an important tool in the testing hierarchy, and may provide interesting insights into their potential clinical efficacy. Agents with demonstrable in vitro antimicrobial activity may be effective against the same microorganisms in vivo, whereas agents without demonstrable in vitro antimicrobial activity are unlikely to exhibit in vivo antimicrobial activity. In addition, these methods may also be useful in screening antimicrobial agents in product formulations because such agents with both in vitro and in vivo activity may have reduced antimicrobial effects when formulated into a dentifrice. Accordingly, this study examined the in vitro and ex vivo antimicrobial activity of three commercial dentifrices: one formulated with 0.243% sodium fluoride (Crest Cavity Protection Toothpaste-Regular); one with 0.454% stannous fluoride, sodium hexametaphosphate, and zinc lactate (Crest Pro-Health), and one with 0.3% triclosan, 2.0% PVM/MA copolymer, and 0.243% sodium fluoride (Colgate Total).

METHODS

The minimum inhibitory concentration (MIC) of each dentifrice was determined for resident oral bacterial species, including bacteria that are associated with dental caries; periodontitis, and oral halitosis. Evaluations were performed on individual laboratory strains, and on oral bacteria from supragingival plaque samples obtained from 10 adults and from oral rinse samples obtained from 18 adults.

RESULTS

The lowest MICs against the oral strains and human samples, i.e., greatest antimicrobial activity, were seen for the triclosan/ copolymer dentifrice. There was, in general, a four-fold difference in MICs between the triclosan/copolymer dentifrice and the stannous fluoride/sodium hexametaphosphate/zinc lactate dentifrice. The triclosan/copolymer dentifrice significantly inhibited periodontal pathogens, such as Aggregatibacter actinomycetemcomitans, Eikenella corrodens, and Fusobacterium nucleatum. In ex vivo tests measuring antimicrobial effects, the triclosan/copolymer dentifrice substantially inhibited bacterial growth after 30-, 60-, and 120-second exposures compared to the sodium fluoride or stannous fluoride/sodium hexametaphosphate/zinc lactate dentifrices. Similarly, in ex vivo tests measuring antimicrobial effects on supragingival plaque biofilms, the triclosan/copolymer dentifrice substantially inhibited bacterial growth compared to the other test dentifrices.

CONCLUSION

Different in vitro and ex vivo analyses show that the triclosan/copolymer dentifrice has significant antimicrobial activity on oral bacteria, including species causing dental caries, periodontitis, and oral halitosis, and it provides superior efficacy compared to the stannous fluoride/sodium hexametaphosphate/zinc lactate dentifrice.

Effect of fluoride solutions on the structure and hardness of plastic brackets

AIM

To investigate the surface morphology, structure, molecular and elemental composition, and hardness of plastic brackets exposed to fluoride solutions.

METHODS

Two types of plastic brackets (Silkon Plus and SpiritMB) were exposed to three fluoride solutions 10 times for 1 minute each and then subjected to attenuated total relectance-Fournier transform infrared (ATR-FTIR) spectroscopy, scanning electron microscopy (SEM), x-ray energy dispersive microanalysis (EDS), and Vickers hardness (HV) testing. Hardness data were analyzed via two-way ANOVA and Tukey tests at the .05 level of significance with brackets and fluoride solution as predictors.

RESULTS

ATR-FTIR spectroscopy showed that both bracket types consisted of polycarbonate. After treatment with acidulated phosphate fluoride, an increased contribution of -OH peaks at 3,200 cm-1(stretching [str]) and 1,640 cm-1 (a type of vibration [b]) was observed in both brackets. SEM revealed that the acidulated phosphate fluoride solution had a strong effect on the morphology and surface structure of the two brackets; a general deterioration with projections of the reinforcing fibers was observed. EDS showed evidence of aluminum, calcium, silicon, magnesium, and titanium, which could be attributed to the reinforcing glass fiber constituents. Hardness ranged in the order of 20 HV with no difference among the two bracket types and the three fluoride exposures.

CONCLUSION

Repeated exposure of plastic brackets to fluoride solutions has a pronounced effect on their structure and morphology, but not their hardness.

A clinical investigation of the efficacy of three commercially available dentifrices for controlling established gingivitis and supragingival plaque

OBJECTIVE

To assess the efficacy ofa dentifrice containing 0.3% triclosan/2.0% PVM/MA copolymer/0.243% sodium fluoride for controlling established gingivitis and supragingival plaque relative to that of a dentifrice containing 0.454% stannous fluoride, sodium hexametaphosphate, and zinc lactate, and a dentifrice containing 0.243% sodium fluoride as a negative control.

METHODS

Following a baseline examination for gingivitis and supragingival plaque, qualifying adult male and female subjects from the Piscataway, NJ, USA area were randomized into three dentifrice groups. Subjects were instructed to brush their teeth twice daily (morning and evening) for one minute with their assigned dentifrice and a soft-bristled toothbrush. Examinations for gingivitis and supragingival plaque were repeated after six weeks of product use.

RESULTS

One-hundred and seventy-one (171) subjects complied with the protocol and completed the study. Relative to the group using the dentifrice with 0.243% sodium fluoride alone, the 0.3% triclosan/2.0% PVM/MA copolymer/0.243% sodium fluoride group exhibited statistically significant reductions in gingival index and supragingival plaque index scores of 25.3% and 33.0%, respectively, after six weeks of product use. Similarly, relative to the group using the 0.243% sodium fluoride dentifrice, the 0.454% stannous fluoride, sodium hexametaphosphate, and zinc lactate dentifrice group exhibited statistically significant reductions in gingival index and plaque index scores of 8.1% and 14.1% after six weeks of product use. Further, relative to the 0.454% stannous fluoride, sodium hexametaphosphate, and zinc lactate dentifrice group, the 0.3% triclosan/2.0% PVM/MA copolymer/0.243% sodium fluoride dentifrice group exhibited statistically significant reductions in gingival index and plaque index scores of 18.7% and 22%, respectively.

CONCLUSION

The overall results of this double-blind clinical study support the conclusion that a dentifrice containing 0.3% triclosan/2.0% PVM/MA copolymer/0.243% sodium fluoride is efficacious for the control of established gingivitis and supragingival plaque as compared to a regular fluoride dentifrice, and that it provides a greater level of efficacy for the control of gingivitis and supragingival plaque than does a dentifrice containing 0.454% stannous fluoride, sodium hexametaphosphate, and zinc lactate.

Comparative investigation of the efficacy of triclosan/copolymer/sodium fluoride and stannous fluoride/sodium hexametaphosphate/zinc lactate dentifrices for the control of established supragingival plaque and gingivitis in a six-month clinical study

OBJECTIVE

This double-blind clinical study, conducted at the University of Puerto Rico, San Juan, Puerto Rico, was designed to compare the efficacy of two commercially available dentifrices for the control of supragingival plaque and gingivitis.

METHODS

Qualifying adult male and female subjects from the San Juan, Puerto Rico area were randomly assigned to one of two treatment groups: 1) a commercially available dentifrice containing 0.3% triclosan, 2.0% PVM/MA copolymer, and 0.243% sodium fluoride (Colgate Total); and 2) a commercially available dentifrice containing 0.454% stannous fluoride, sodium hexametaphosphate, and zinc lactate (Crest Pro-Health). All subjects received an oral soft and hard tissue examination, and were dispensed their assigned dentifrice product, along with a soft-bristled adult toothbrush for home use. Subjects were instructed to brush their teeth for one minute, twice daily (morning and evening), using only the dentifrice provided. Examinations for supragingival plaque and gingivitis, and oral soft and hard tissue assessments were repeated after six weeks, three months, and six months of product use.

RESULTS

One-hundred and nine (109) subjects complied with the protocol and completed the six-month examinations. At the six-month examination, both treatment groups exhibited statistically significant reductions from baseline with respect to supragingival plaque and gingivitis scores. Relative to the Crest Pro-Health Toothpaste group, the Colgate Total Toothpaste group exhibited statistically significant reductions in supragingival plaque index scores of 18.5%, 20.7%, and 25.8% after six weeks, three months, and six months of product use, respectively. For gingival index scores, statistically significant reductions of 20.5%, 18.9%, and 17.1% were exhibited after six weeks, three months, and six months of product use, respectively.

CONCLUSION

The results of this double-blind clinical study support the conclusion that a dentifrice containing 0.3% triclosan, 2.0% PVM/MA copolymer, and 0.243% sodium fluoride provides a significant reduction in established supragingival plaque and gingivitis, as compared to a dentifrice containing 0.454% stannous fluoride, sodium hexametaphosphate, and zinc lactate when used over a period of six months.

A comparison of the efficacy of a triclosan/copolymer/sodium fluoride dentifrice, a stannous fluoride/sodium hexametaphosphate/zinc lactate dentifrice, and a sodium fluoride dentifrice for the control of established supragingival plaque and gingivitis: a six-week clinical study

OBJECTIVE

To compare the efficacy ofa dentifrice containing 0.3% triclosan, 2.0% PVM/MA copolymer, and 0.243% sodium fluoride in controlling established gingivitis and supragingival plaque to that of a commercially available dentifrice containing 0.454% stannous fluoride, sodium hexametaphosphate, and zinc lactate, and a commercially available dentifrice containing 0.243% sodium fluoride.

METHODS

Following a baseline examination for gingivitis and supragingival plaque, qualifying adult male and female subjects from the Mississauga, Ontario, Canada area were randomized into three dentifrice groups. Subjects were instructed to brush their teeth twice daily (morning and evening) for one minute with their assigned dentifrice and a soft-bristled toothbrush. Examinations for gingivitis and supragingival plaque were repeated after six weeks of product use.

RESULTS

One-hundred eighty-two (182) subjects complied with the protocol and completed the study. Relative to the 0.243% sodium fluoride dentifrice group, the 0.3% triclosan/2.0% PVM/MA copolymer/0.243% sodium fluoride dentifrice group exhibited statistically significant reductions in gingival index and supragingival plaque index scores of 26.5% and 29.4%, respectively, after six weeks of product use. Similarly, relative to the 0.243% sodium fluoride dentifrice group, the 0.454% stannous fluoride/sodium hexametaphosphate/zinc lactate dentifrice group exhibited statistically significant reductions in gingival index and plaque index scores of 12.7% and 12.6%, respectively, after six weeks of product use. Further, relative to the 0.454% stannous fluoride/sodium hexametaphosphate/zinc lactate dentifrice group, the 0.3% triclosan/2.0% PVM/MA copolymer/0.243% sodium fluoride dentifrice group exhibited statistically significant reductions in gingival index and plaque index scores of 15.8% and 19.2%, respectively.

CONCLUSION

The overall results of this double-blind clinical study support the conclusion that a dentifrice containing 0.3% triclosan, 2.0% PVM/MA copolymer, and 0.243% sodium fluoride is efficacious for the control of established gingivitis and supragingival plaque, and that it provides a greater level of efficacy for the control of gingivitis and supragingival plaque than does a dentifrice containing 0.454% stannous fluoride, sodium hexametaphosphate, and zinc lactate.

Increased Salivary Fluoride Concentrations after Post-Brush Fluoride Rinsing Not Reflected in Dental Plaque

The aim of the present study was to assess fluoride concentrations in unstimulated saliva and buccal dental plaque 6 h after an oral hygiene procedure that consisted of brushing with an AmF/SnF2 dentifrice and different post-brush rinsing protocols: expectorating the excess of dentifrice foam and rinsing with tap water, expectorating only, or rinsing with 10 ml AmF/SnF2 mouthwash. The fluoride concentrations in plaque and saliva were increased after all three experimental protocols compared to F-free periods. The increase of the fluoride concentration in saliva was more pronounced after AmF/SnF2 mouthrinse as compared to rinsing with water and expectorating the excess of dentifrice foam. Such an effect was not seen in dental plaque. It is concluded that the potentially beneficial effect of not rinsing or fluoride rinsing after tooth brushing is not reflected in an increased fluoride concentration in newly formed dental plaque 6 h after brushing.

The radiopharmaceutical chemistry of 99mTc-tin fluoride colloid-labeled-leukocytes

Tc-99m-tin fluoride colloid is a radiotracer used to label patient white cells, for the diagnosis of infection and inflammation. The scintigraphic technique has been employed in routine clinical practice for approximately 20 years in Australia, yet the chemistry of the radiolabeling agent, and the physiological distribution of (99m)Tc-leukocytes, are not entirely understood. In this review, the physico-chemical characteristics of (99m)Tc-tin fluoride colloid are discussed, as well as the in vitro and in vivo distribution of (99m)Tc-tin fluoride-labeled-leukocytes. Furthermore, important animal and human studies are summarized, that emphasize the clinical usefulness of this radiopharmaceutical tracer in nuclear medicine today.

A novel dentifrice technology for advanced oral health protection: A review of technical and clinical data

Throughout the world, dentifrices have played a key role in the practice of good oral hygiene and promotion of better oral health. In addition to providing general dental cleaning, toothpastes also have served as an excellent vehicle for the introduction of new agents that deliver therapeutic and cosmetic benefits. Key examples of using dentifrices to provide added benefits include the introduction in 1955 of the first fluoridated toothpaste clinically proven to fight caries (Crest Cavity Protection) and the launch of the first tartar-control dentifrice (Crest Tartar Control) in the mid-1980s. To continue expanding the health and esthetic benefits offered by a single dentifrice, a multitude of agents have been investigated over the past 3 decades. The focus of these investigations has been in the multibenefit segment, the most widely used among US consumers.

Corrosion resistance of three orthodontic brackets: a comparative study of three fluoride mouthwashes

In the present study, three types of orthodontic brackets were investigated: cobalt-chromium (CoCr), iron-chromium-nickel (FeCrNi) and titanium (Ti) based. Their corrosion resistance was compared with that of platinum (Pt), which was chosen as the reference material because of its excellent electrochemical properties. The test solutions were Elmex, Meridol and Acorea fluoride mouthwashes. Fusayama Meyer artificial saliva was used as the reference solution. The corrosion resistance of the different brackets in the three mouthwashes was assessed electrochemically to determine the corrosion potential and corrosion current density, and polarization resistance values were then calculated. A scanning electron microscopic (SEM) study and an analysis of released metal ions confirmed the electrochemical studies. The results showed that the bracket materials could be divided into two groups: Ti and FeCrNi in one, and CoCr, which has properties close to those of Pt, in the other. Similarly, two groups of electrolytes were identified: Elmex and Acorea mouthwashes in one group, and Meridol mouthwash in the second group. The results indicate that because of the risk of corrosion Meridol mouthwash should not be prescribed for patients wearing Ti or FeCrNi-based orthodontic brackets.

Effect of fluoride and 10% carbamide peroxide on the surface roughness of low-fusing and ultra low–fusing porcelain

STATEMENT OF PROBLEM

The effect of repeated applications of fluoride solutions and 10% carbamide peroxide on the surface roughness of newer dental porcelains is not completely known.

PURPOSE

The purpose of this study was to compare the surface roughness of 3 different porcelains when exposed to 2 fluoride solutions, a 10% solution of carbamide peroxide, and distilled water.

MATERIAL AND METHODS

Forty discs (10-mm diameter, 2 mm thick) were made of each of the following porcelains: feldspathic porcelain (Ceramco II), low-fusing porcelain (Finesse), and an aluminous porcelain (All-Ceram). Each disc was abraded with a medium-grit diamond bur and auto-glazed. One side of each disc was abraded with a diamond bur and polished using a porcelain polishing kit to simulate a chairside adjustment and polishing. The discs (10 specimens/group) were immersed in 1.23% APF, 0.4% stannous fluoride, 10% carbamide peroxide, and distilled water for 50 seconds (control). The discs in the 10% carbamide peroxide solution were immersed for 48 hours. The surface of each disc was evaluated with surface profilometry (0.1 mm/s speed, 600-microm range). The data were analyzed by factorial analysis of variance and a Tukey multiple comparison test, (alpha=.05).

RESULTS

The data showed that the acidulated phosphate fluoride etched the auto-glazed surface of all 3 porcelains. For Finesse specimens, the mean Ra values for the auto-glazed surface were significantly higher than that of the control after immersion in 1.23% APF (mean Ra 0.3 +/- 0.06 microm, P<.031). All-Ceram auto-glazed surface specimens had a significantly higher mean Ra value when immersed in the 3 solutions than the control (1.23% APF, 0.4% stannous fluoride, and 10% carbamide peroxide, 0.245 +/- 0.115 microm, 0.22 +/- 0.104 microm, 0.22 +/- 0.04 microm, respectively; P<.002). Ceramco II specimens were affected by all 3 solutions, with the auto-glazed surface having higher Ra values (1.23% APF, 0.4% stannous fluoride, and 10% carbamide peroxide, with mean Ra values of 0.35 +/- 0.1 microm, 0.26 +/- 0.08 microm, and 0.24 +/-.0.05 microm, respectively, P=.001). Immersion in the 3 solutions had no effect on the polished surfaces of all-ceramic specimens tested.

CONCLUSION

Prior to the use of fluoride and 10% carbamide peroxide, dentists should ascertain the type of porcelain restoration present to prevent a roughened surface from occurring.

[Amine fluoride does not cause disintegration of glass ceramics]

Topical application of fluoride has been proven to be an effective method for the prevention of dental caries. Some authors have, however, pointed at the etching potential of topically applied fluoride and argued that some products might etch and roughen the surface of ceramic restorations. The aim of the present study was to assess whether the topical application of an acidulated fluoride gelée in vivo leads to a damage of glass ceramic. It was shown that individual brushing with an acidulated fluoride gelée according to the manufacturers prescription is not harmful to ceramic restoration material.

Comparison of the effect of topical fluorides on the commercially available conventional glass ionomers, resin modified glass ionomers and polyacid modified composite resins--an in vitro study

This study was undertaken to assess the effect of a single application of three professionally applied topical fluoride agents (Sodium fluoride 2%, Stannous fluoride 8% and APF 1.23%) on the surfaces of six modern esthetic restorative materials used in pediatric dentistry viz., two conventional glass ionomers (Fuji II and Shofu-restorative), two resin modified glass ionomers (Vitremer, with and without glaze, and Photac-fil Quick) and two Polyacid modified composite resins (Luxat and Hytac Aplitip). Mean surface roughness and surface micro hardness (SMH) measurements were the parameters employed for comparison. Results showed that APF gel applications significantly increased the surface roughness measurements and decreased SMH of all tested materials, which was pronounced in conventional glass ionomers when compared with resin modified glass ionomers and polyacid modified composite resins. NaF and SnF2 produced a statistically significant increase in the surface roughness of conventional glass ionomers without any significant change in surface roughness and SMH on rest of the materials tested, except for NaF on SMH values of Fuji II, which was statistically significant.

Surface changes induced by fluoride prophylactic agents on titanium-based orthodontic wires

This study investigated the effect of fluoride prophylactic agents on the surfaces of titanium-based orthodontic wires. Four types of titanium-based orthodontic wires (2 nickel-titanium alloy wires [nickel-titanium and copper-nickel-titanium] and 2 beta-titanium alloy wires [titanium-molybdenum and titanium-niobium], all from Ormco, Glendora, Calif) with similar sizes were prepared and immersed in 5 fluoride prophylactic agents (2 acidulated phosphate fluoride agents [Nupro APF (Dentsply International, York, Pa) and Florentine III (Confi-Dental, Louisville, Colo)], 1 neutral agent [Neupro Neutral (Dentsply International)] and 2 stannous fluoride agents [Florentine II (Confi-Dental) and Perio-Med (Omni International, Warrenton, Va)]) for 5 minutes, 1 hour, and 24 hours. After immersion, average surface roughness and color changes were evaluated. The surface changes were observed with a scanning electron microscope. The average surface roughness data were statistically analyzed by analysis of variance and Tukey post hoc test at a significance level of alpha = 0.05. There were no significant differences in average surface roughness value among fluoride solutions or orthodontic wires, except for the titanium-molybdenum wire, which showed significantly (P <.05) higher average surface roughness values after immersion in Nupro APF for 24 hours. The results suggested that a few applications of acidulated phosphate fluoride agents might change the surface color of the beta-titanium alloy wires, particularly the titanium-molybdenum wire, which contains a large amount (about 80%) of titanium.

Retention, marginal leakage, and cement solubility of provisional crowns cemented with temporary cement containing stannous fluoride

PURPOSE

This in vitro study investigated the (1) retention and microleakage of provisional crowns cemented with temporary cements to which stannous fluoride (SnF2) was added, and (2) solubility of these cements.

MATERIALS AND METHODS

Provisional crowns were constructed of acrylic resin with shoulder preparations for 12 molars. The crowns were luted with Tempbond, Tempbond NE, and Freegenol temporary cements, and also with SnF2 added to these cements. Specimens were thermocycled 100 times, stored for 6 days, and immersed in 0.5% basic fuschin. Seven days after cementation, crown removal (retention) tests were conducted. Marginal leakage was assessed using a five-level scale to score dye penetration. Solubility in water of the cements with and without SnF2 was assessed using cement disks.

RESULTS

Freegenol was more retentive than the other cements. The incorporation of SnF2 significantly increased the retention capacity of Freegenol and Tempbond NE but had no effect on Tempbond. Tempbond showed significantly higher dye penetration than Freegenol. The addition of SnF2 did not alter the dye penetration of the cements. There were no significant differences in the solubility of the cements. However, the incorporation of SnF2 increased the solubility of Freegenol and Tempbond NE (P < .001) and Tempbond (P < .01).

CONCLUSION

The addition of SnF2 increased the retention of temporary crowns cemented with Tempbond NE and Freegenol but did not affect the retention of those cemented with Tempbond. The marginal leakage of crowns cemented with the tested temporary cements with and without the incorporation of SnF2 was similar. However, the addition of SnF2 increased the solubility of the cements.

99mTc-SnF2 colloid "LLK": particle size, morphology and leucocyte labelling behaviour

99mTc-SnF2 colloid (Radpharm LLK) leucocyte labelling agent is used in whole blood, exploiting phagocytosis. The objectives of this work were to optimize leucocyte labelling in leucocyte-enriched plasma, and to investigate: (i) the effect of temperature and other factors on labelling efficiency; (ii) the selectivity for different leucocyte types; (iii) the viability of the labelled cells and efflux of the radiolabel; and (iv) the physical characteristics of the colloid. Density gradient centrifugation was used to investigate the labelling efficiency, cell selectivity and efflux, Trypan blue to study the viability, and laser scattering, electron microscopy and membrane filtration to investigate particle size and morphology. Particles appeared as loose, coiled, chain-like aggregates of much smaller particles (<0.05 microm). The aggregate diameter ranged from <0.1 to >5 microm and increased with time. The distribution of radioactivity amongst the particle sizes varied widely. The labelling efficiency in leucocyte-rich plasma was enhanced at 37 degrees C compared to room temperature, and by centrifuging during labelling. The selectivity for different leucocyte types varied markedly between batches and blood samples, in some cases showing preference for mononuclear cells and in others for granulocytes. Viability was excellent and comparable with 99mTc-hexamethylpropyleneamine oxime (99mTc-HMPAO)-labelled cells. A significant fraction of radiolabel, comparable to that observed with 99mTc-HMPAO, was lost from leucocytes during incubation in vitro over 4 h. Thus, 99mTc-SnF2 is a convenient, efficient labelling agent for leucocytes, but shows variable cell selectivity which may be linked to particle size variability, and there is significant efflux of radioactivity from labelled cells.

[Influence of the buffer capacity of amine fluoride-containing toothpastes and gels in enamel erosion]

The aim of the study was to evaluate the abrasion resistance of eroded enamel brushed with experimental toothpastes and fluoride gels of varying buffering capacities. 50 Specimens were prepared from extracted human molars and cycled through three alternating de- and remineralizations including brushing abrasion in a brushing machine. Demineralization was accomplished by immersing the samples in 1% citric acid (5 min), remineralization occurred during immersing the samples in artificial saliva (1 min). Groups of ten samples were brushed with either one of the toothpaste (A-C) or one of the fluoridated gels (D-E). Toothpastes and gels were produced on the basis of elmex toothpaste or elmex-gelée (GABA International AG, Switzerland). Amount of titrable acid was defined as amount (mg) of 1 N KOH needed for neutralization of 1 g toothpaste or gel (A: 6 mg, B: 12 mg, C: 24 mg, D: 3.1 mg, E: 10 mg KOH). The following abrasion values (mean + S.D. [micron]) were obtained profilometrically: A: 6.76 +/- 2.05, B: 6.84 +/- 1.19, C: 8.28 +/- 2.89, D: 4.19 +/- 1.09 and E: 0.83 +/- 0.61. No significant difference in abrasion between the toothpastes was found. The fluoride gel with the higher buffering capacity (E) exhibited significantly less abrasion than the gel with the lower buffering capacity (D). It is concluded that in eroded enamel buffering capacity of the tested fluoridated toothpastes has no effect on abrasion, whereas use of fluoride gel with a higher buffering capacity leads to reduced abrasion values.

Effects of professionally applied topical fluorides on surface hardness of composite-based restoratives

This study investigated the effects of professionally applied topical fluorides on the surface hardness of a composite (Spectrum TPH), a compomer (DyractAP) and a giomer (Reactmer). Thirty specimens of each material were fabricated and stored in distilled water at 37 degrees C for one week. These specimens were then randomly divided into five groups of six and treated for 36 hours at 37 degrees C with one of the following: distilled water (control), 1.23% acidulated phosphate fluoride (APF) foam, 0.9% neutral foam, 1.23% APF gel and 0.4% stannous fluoride gel. The treated specimens were subsequently subjected to microhardness testing (load = 500 gf; dwell time = 15 seconds). Results were analyzed using ANOVA/Scheffe's test (p<0.05). The effects of topical fluoride application on surface hardness was material dependent. For all materials, treatment with APF gel and foam significantly reduced surface hardness when compared to the control. KHN values after exposure to APF gel were consistently the lowest and ranged from 4.53 to 15.97. Control KHN values were higher, ranging from 32.88 to 47.47. The surface hardness of the compomer was also significantly reduced after exposure to neutral foam. Therefore, the use of professionally applied topical fluorides, especially APF gel and foam, may be detrimental to the long-term durability of composite-based restoratives.

Clinical efficacy of an optimized stannous fluoride dentifrice, Part 2: A 6-month plaque/gingivitis clinical study, northeast USA

The objective of this 6-month, double-blind clinical study, conducted following the American Dental Association guidelines, was to investigate the efficacy of Colgate Optimized Stannous Fluoride (COSF) dentifrice for the control of supragingival dental plaque and gingivitis. This dentifrice contains 0.454% stannous fluoride, stannous chloride, polyphosphate, and citrate in a silica base. At the 3- and 6-month study examinations, the COSF dentifrice group exhibited statistically significant reductions in both plaque and gingivitis compared to the control dentifrice group. At the 6-month examination, the magnitude of these percent reductions exceeded 20% for all 4 parameters measured. Thus, the results of this study support the conclusion that the COSF dentifrice is efficacious for the control of supragingival plaque and gingivitis.

Clinical efficacy of an optimized stannous fluoride dentifrice, Part 3: A 6-month plaque/gingivitis clinical study, southeast USA

This 6-month, double-blind clinical study, also following the American Dental Association guidelines, investigated the efficacy of Colgate Optimized Stannous Fluoride (COSF) dentifrice in controlling supragingival dental plaque and gingivitis. The same dentifrice, containing 0.454% stannous fluoride, stannous chloride, polyphosphate, and citrate in a silica base was used. Adult men and women from the Atlanta, Georgia, area received an oral prophylaxis and were instructed to brush their teeth twice daily (morning and evening) for 1 minute with their assigned dentifrice, using a soft-bristled toothbrush. As in the first study, plaque and gingivitis examinations were conducted after 3 months and again after 6 months of using the dentifrices. At both the 3- and 6-month study examinations, the COSF dentifrice group exhibited statistically significant reductions in both plaque and gingivitis compared to the control dentifrice group. At the 6-month examination, the magnitude of these percent reductions exceeded 20% for all 4 parameters measured. Thus, the results of this study reflect those found in the New Jersey study, i.e., supporting the conclusion that the COSF dentifrice is efficacious for the control of supragingival plaque and gingivitis.

Clinical efficacy of an optimized stannous fluoride dentifrice, Part 4: A 3-month calculus clinical study, northwest USA

The objective of this 3-month, double-blind study was to investigate the efficacy of Colgate Optimized Stannous Fluoride (COSF) dentifrice for the control of supragingival dental calculus accumulation. After 3 months' use, the COSF dentifrice group exhibited a statistically significant 56.6% reduction in supragingival calculus formation, as compared to the control dentifrice group. The results of this study support the conclusion that the COSF dentifrice is efficacious for controlling the accumulation of supragingival calculus.

The scientific rationale and development of an optimized stannous fluoride dentifrice, Part 1

Stannous fluoride has been recognized as an effective anticavity therapeutic agent since the early 1950s. There has recently been a resurgence in activity to discover ways to fully exploit its documented antimicrobial activity. Through the use of targeted in vitro methodology to predict in vivo efficacy, a highly optimized stannous fluoride dentifrice has been developed. Careful selection of stabilizing agents formulated into a unique system has resulted in a Colgate Optimized Stannous Fluoride (COSF) dentifrice that has been proven to simultaneously help control supragingival plaque, gingivitis, supragingival calculus, and caries. Furthermore, the COSF dentifrice has been clinically shown not to cause the traditional stannous fluoride staining of dentition.

Clinical efficacy of an optimized stannous fluoride dentifrice, Part 5: A 3-month study of extrinsic tooth staining, northeast USA

The objective of this 3-month, double-blind clinical study was to investigate the level of tooth staining associated with the use of Colgate Optimized Stannous Fluoride (COSF) dentifrice compared to the tooth staining associated with two commercially available dentifrices. The results of this clinical study support the conclusion that the intensity and extent of extrinsic tooth stain associated with the use of the COSF dentifrice are significantly lower than that associated with Crest Gum Care Toothpaste. Further, this study provided no indication that the use of the COSF dentifrice is associated with a greater level of stain than that associated with the use of Crest Regular Toothpaste, a standard 0.243% sodium fluoride/silica dentifrice.

Stille couplings catalytic in tin: a "Sn-F" approach

A new tin recycling method for Stille couplings catalytic in tin is reported. PMHS made hypercoordinate by KF((aq)) allows Me(3)SnH to be efficiently recycled during a Pd(0)-catalyzed hydrostannation/Stille cascade. Relative to previously disclosed protocols, reaction times are shorter and because this process is believed to proceed through a Me(3)SnF intermediate the hazards and problems associated with trimethyltins are also diminished.[reaction: see text]

Effect of experimental fluoride-releasing tooth separator on acid resistance of human enamel in vitro

This study aimed to investigate the fluoride-releasing ability of an experimental tooth separator consisting of polyurethane elastomer with tin fluoride and its effect on the acid resistance of human enamel. The tooth separator was set around an enamel slab and stored in de-ionized water for 10 days. The daily concentration of fluoride in the de-ionized water was measured. Then the enamel surface was artificially decalcified by a lactic acid buffer solution (pH 4.5) for 96 hours. The mineral density at the surface layer of the enamel was measured to evaluate the acid resistance. The fluoride release increased with the amount of fluoride in the separator, but decreased with the immersion time. Both the enamel area contacting with the separator and its surrounding area showed lower mineral loss and lesion depth compared with the controls (P < 0.05). It is suggested that the experimental tooth separator would release enough fluoride and improve the acid resistance of the enamel surface layer.

Sensitivity of titanium brackets to the corrosive influence of fluoride-containing toothpaste and tea

Titanium brackets are used in orthodontic patients with an allergy to nickel and other specific substances. In recent studies, the corrosive properties of fluoride-containing toothpastes with different pH values were investigated. The present in vivo study tested how the surfaces of titanium brackets react to the corrosive influence of acidic fluoride-containing toothpaste during orthodontic treatment. Molar bands were placed on 18 orthodontic patients. In these same patients, titanium brackets were bonded on the left quadrants and stainless steel brackets on the right quadrants of the upper and lower arches. Fifteen patients used Gel Kam containing soluble tin fluoride (pH 3.2), whereas 3 used fluoride-free toothpaste. The brackets were removed for evaluation by light microscopy and scanning microscopy 5.5 to 7.0 months and 7.5 to 17 months after bonding. The quality and quantity of elements present were measured by scanning microscopy. Macroscopic evaluation showed the matte gray color of titanium brackets dominating over the silver gleam of the steel brackets. The plaque accumulation on titanium brackets is high because of the very rough surface. Pitting and crevices were observed in only 3 of the 165 brackets tested. The present in vivo investigation confirms the results of in vitro studies, but the changes are so minor that titanium brackets can safely be used for up to 18 months. Wing surfaces should be improved by modifying the manufacturing process.

A comparative study of 2 fluoride-based mouthrinses

OBJECTIVE

The purpose of this study was to compare the effectiveness of 2 mouthrinses (conventional Meridol and alcohol-free Meridol).

METHOD AND MATERIALS

A controlled, single-blind clinical study of 3 weeks' duration was conducted on 80 adult subjects in good general health and without severe periodontitis (probing depths no deeper than 4 mm). The mouthrinses supplemented regular measures of oral hygiene for the reduction of plaque and gingivitis. In preliminary examinations to determine general conditions of oral health, especially the level of plaque, gingivitis, and periodontal findings, the approximal plaque index, sulcular bleeding index, and gingival index were established for each subject. Afterward the subjects were provided with a professional toothcleaning, as required. Each subject was randomly provided with 1 of the 2 mouthrinses, to be used 3 times daily in addition to routine oral health measures. The 3 indexes were reevaluated after 3 weeks; in addition, an optional stain index was employed.

RESULTS

In both subject groups, a statistically significant reduction in plaque accumulation, as well as a reduction in inflammation and the tendency to bleeding, was observed. Reversible staining of the teeth and tongue was observed in fewer than one third of the subjects in both groups.

CONCLUSION

Comparison of the 2 Meridol mouthrinses revealed no difference in effectiveness related to the alcohol content.

Fluoride release and uptake by aged resin-modified glass ionomers and a polyacid-modified resin composite

Little has been reported of the relationship of fluoride release and weight loss, and the effects of use of different fluoride agents on restorations, for the new generation of glass ionomer cements. The objectives of this study were to compare fluoride release of fresh and aged specimens of a polyacid-modified resin composite (Dyract), and of three resin-modified glass ionomer cements (Fuji II LC, Photac-Fil, Vitremer); and to correlate fluoride release and weight loss of aged specimens after recharging with three different fluoride agents. All materials showed high initial fluoride release immediately after uptake when using the agents. However, the levels of fluoride release dropped rapidly soon afterwards. Although initial fluoride release was significantly different between Dyract and the three resin-modified glass ionomers, when different fluoride agents were used on aged specimens after recharging, no significant differences were found after the first few hours. Linear regression analyses also showed no correlation between cumulative fluoride release and weight loss. Possible beneficial oral health effects may only be expected by frequent exposure of these materials to fluoride agents.

Studies on fluoridated toothpicks

The aim of this thesis was to evaluate the wooden toothpick as a vehicle for the delivery of fluoride to the approximal area. After two minutes use in vivo, the release of fluoride from the pointed section of a toothpick impregnated in 4% NaF was estimated to 0.15 mg. Toothpicks produced similar or somewhat higher fluoride concentrations in the approximal area compared with other fluoride-containing products, like dentifrice, mouthrinse solution and tablet. The mean fluoride concentration in an approximal area treated for two minutes with a toothpick impregnated in 4% NaF was around 11 mM/l. Toothpicks impregnated in 4% NaF, 8% SnF2 or 2% chlorhexidine had an effect on the proportion of mutans streptococci and on the decline of pH in dental plaque, but it was small and only of short duration. The recolonization of mutans streptococci was, however, slower after using the SnF2- and chlorhexidine-impregnated toothpicks than after using the NaF- and non-impregnated toothpicks. The effect of fluoridated toothpicks on the degree of de- and remineralization of enamel and dentine was measured using transversal microradiography in an in situ study. Four weeks' use of toothpicks, especially of NaF-impregnated toothpicks, reduced the degree of demineralization of enamel and dentine at approximal sites. Secondary ion mass spectrometry was also used to determine the fluoride content in the outer surface of dentine, which increased more than 10 times after using fluoride toothpicks compared with non-impregnated toothpicks. In a second in situ study, 4% NaF-, 2% chlorhexidine- and non-impregnated toothpicks had a similar effect on sound and demineralized enamel and on demineralized dentine. However, the NaF toothpicks were superior in terms of their effect on sound dentine. The effect on mutans streptococci and plaque-pH, on the other hand, was the same for all three types of toothpicks. The main conclusion from this thesis is that the wooden toothpick is a suitable vehicle for the delivery of fluoride to the approximal area.

Effects of topical fluoride treatment on tensile bond strength of pit and fissure sealants

Clinicians often do not place pit and fissure sealants immediately after topical fluoride treatment because fluoride treatment might reduce bonding to enamel. The effect of NaF, SnF2, and APF on the in-vitro bond strength of two sealants to enamel was determined. The fluoride treatments and control (artificial saliva) were applied to enamel surfaces for four minutes and rinsed. A filled sealant (FluoroShield) and an unfilled sealant (Concise) were bonded to the etched enamel and debonded in tension using a universal testing machine. NaF increased the bond strength of the unfilled sealant; SnF2 and APF had no significant effect. NaF and APF decreased the bond strength of filled sealant while SnF2 had no significant effect. The bond strength of the filled sealant was higher than or equal to that of the unfilled sealant. Exposure of enamel to NaF, SnF2, or APF prior to placement of unfilled or filled sealants has no effect on in vitro bond strength between the enamel and the sealants.

Effects of daily topical fluoride gels on resin composite degradation and wear

OBJECTIVES

This in vitro study compares the effects of professional and consumer-applied topical fluorides on the weight, wear resistance and surface appearance of a resin composite containing barium boroaluminosilicate glass filler particles.

METHODS

Prior to wear studies with a pin and disc apparatus, specimens were immersed for 6 min 10 times in water, three consumer-applied topical fluorides (1.1% NaF, 0.4% SnF2, or 0.5% APF gel) or a professionally applied topical fluoride (1.23% APF gel). Specimens were weighed before and after each immersion. Following wear studies, the specimen surfaces were visually evaluated using scanning electron microscopy. Weight changes were analyzed for significant differences using one-way ANOVA and Duncan's multiple range test (p = 0.01). Values of wear parameters were ranked and tested for significance using one-way ANOVA with least squares mean contrast (p = 0.05).

RESULTS

Significant differences were found in the weight loss of specimens treated with different fluoride agents: 1.23% APF = 0.5% APF > 0.4% SnF2 > 1.1% NaF = water (p < or = 0.0001). Significant differences in initial wear depth (S(i)) occurred in the following samples: 1.23% APF > 1.1% NaF = 0.5% APF (p = 0.04). Scanning electron micrographs showed variable wear tracks on the specimen surfaces. The specimen surfaces outside the wear track were smooth for those treated with water or with NaF; the surfaces outside the wear track of specimens treated with APF showed extensive loss of filler particles.

SIGNIFICANCE

Topical APF agents caused extensive loss of filler from the resin composite specimens whereas 1.1% NaF caused the least damage. Although significant differences in surface wear resistance were detected, clinical studies are needed to determine the effect of topical fluorides on the properties of this resin composite.

Studies on stannous fluoride toothpaste and gel (1). Antimicrobial properties and staining potential in vitro

Stannous fluoride (SF) in a toothpaste vehicle has the potential to provide anticaries and plaque inhibitory benefits through the fluoride and antimicrobial stannous moieties respectively. Dental staining, however, can occur by precipitation of dietary chromogens onto the tooth surface by stannous ions. These studies in vitro compare the antimicrobial profile and propensity to cause tea staining of a number of stannous fluoride formulations. The formulations used were 2 SF toothpaste products (SF1, SF2), 2 experimental SF plus stannous pyrophosphate toothpastes (SFSP1, SFSP2), a SF gel (G) and a NaF toothpaste (C). Maximum inhibitory dilution values against a range of oral bacteria were determined by agar dilution. Tea staining was measured spectrophotometrically on saliva coated clear acrylic blocks exposed to slurries of the paste or gel. All formulations showed antimicrobial activity with the order of greatest activity downwards being C, SF2, SF1, SFSP1, SFSP2 and G. Tea staining at 10 exposures was in the following descending order of optical density SFSP1, SFSP2, G. C, SF1, SF2, water control. The antimicrobial profile of G was similar to that of SF, whereas that of the other formulations were varied but similar to a detergent profile. The difference in staining suggested considerable variation in availability of stannous ions in the formulations. However, the propensity for stannous ions to stain must be balanced against the stain removal propensity of the contained detergents in the toothpaste formulations. In conclusion, the variation in antimicrobial activity and more particularly staining activity of the formulations suggest the products will vary in activity in vivo.

Topical fluoride and glass ionomer microhardness

PURPOSE

To evaluate the effect of topical fluoride gels on the microhardness of three glass ionomer cements.

MATERIALS AND METHODS

Cylinders of Ketac-Silver, Photac-Fil, and Fuji II LC were fabricated, stored in distilled water at 37 degrees C for 48 hours, and exposed to a neutral sodium fluoride gel (Karigel-N), and acidulated orthophosphoric acid gel (Karigel), and a stannous fluoride gel (Omni) at 37 degrees C for 36 hours. Knoop hardness was then recorded.

RESULTS

Statistical analysis showed significant differences (P<0.01) between groups related to material and treatment Ketac-Silver did not demonstrate significant differences in hardness, whereas exposure to APF decreased the Knoop hardness of Fuji II LC and Photac-Fil.

Influence of fluoride applications on some physicochemical surface properties of synthetic hydroxyapatite and human dental enamel and its consequences for protein adsorption

Synthetic hydroxyapatite and human dental enamel (polished and non-polished) were subjected to various fluoride applications, i.e., using solutions of sodium fluoride (NaF), acidulated phosphate fluoride (APF), and stannous fluoride (SnF2). Treatment with APF has a strong influence on the morphology of the apatite. All fluorides, in particular SnF2, make the enamel surfaces more hydrophobic. NaF and APF applications slightly alter the electrokinetic potentials of the surfaces, but SnF2 renders them much more negatively charged. The adsorption of the proteins lysozyme and alpha-lactalbumin on these surfaces can be explained in terms of electrostatic and hydrophobic interactions between the proteins and the sorbent surfaces.

The effect of topical fluorides on ceramic brackets

Topical fluorides are frequently prescribed to orthodontic patients to minimize development of initial carious lesions around brackets and bands. However, various topical fluorides are reported to cause surface changes and weight loss of dental materials composed of ceramic elements. Little is known of the effects of these fluorides on ceramic brackets. The purpose of this study was to determine the effects of topical fluorides (0.4% stannous fluoride, 0.5% acidulated phosphate fluoride, and 1.1% sodium fluoride) as compared with water, on the weight and on the surface of the wings and slots of aluminum oxide ceramic brackets. The brackets (n = 10 each treatment agent) were weighed before 6-minute immersions in the treatment agent, rinsed, dried, and reweighed for a total of 10 immersions. The surface appearance of the wings and the slots of the brackets (n = 5 each treatment group) were evaluated with scanning electron microscopy. No statistically significant changes in weight were found among the groups. Surface changes were not observed in either the slots nor the wings of ceramic brackets. Therefore it was concluded that the commercially available topical fluorides when applied as per the regimen in this study to the aluminum oxide ceramic brackets did not cause surface damage or significant weight loss as compared with controls (water).

Recent advances in stannous fluoride technology: antibacterial efficacy and mechanism of action towards hypersensitivity

Stannous fluoride (SnF2) is highly susceptible to oxidation and hydrolysis but both anhydrous and aqueous preparations can be well established by proper formulation. When stability in aqueous preparations is achieved by the use of certain strong complexing agents, reduced antibacterial activity is observed which may be attributed to reduced bioavailability of the stannous ion. In contrast, an anhydrous SnF2 preparation maintains stannous ion in a stable but, uncomplexed form. This preparation displays antibacterial activity in saliva and delivers stannous ion which is absorbed onto surfaces making them less susceptible to plaque formation for an extended period of time (hours). When this anhydrous preparation is brushed onto dentine in vitro or in situ, one observes a nearly complete coverage of the dentine surface and occlusion of tubules by a tin-rich surface deposit. This finding indicates that the observed clinical efficacy of this preparation at relieving hypersensitivity is due to occlusion of tubules by a mixture of low solubility complexes of tin. A water-based SnF2 preparation containing strongly complexed stannous ions does not form a surface coating on dentine in vitro suggesting that this preparation may not be optimal for treating hypersensitivity. Overall, the findings indicate that the stannous ions in a SnF2 preparation must be maintained in a stable, bioavailable form for optimal efficacy against plaque and hypersensitivity to be obtained. The results suggest that these properties are provided by stable anhydrous preparations but are difficult to achieve simultaneously in aqueous preparations. When properly formulated, stannous fluoride preparations can provide multiple oral therapeutic benefits.

Clinical effects and possible mechanisms of action of stannous fluoride

Stannous fluoride was frequently used as a vehicle for fluoride in preparations used in caries prophylaxis in the 1960s and 1970s. At present it is not much used, although extensive research during the last two decades has established that stannous fluoride possesses several interesting properties which demonstrate that it deserves to be used in the prophylaxis against both gingivitis and caries. In the following, a review of the clinical properties of stannous fluoride is presented, together with a discussion of its merits compared with other fluoride vehicles in current use.

Effect of home-use fluoride gels on glass ionomer and composite restorations

The effect of home-use topical fluorides on the surface integrity of two glass ionomers and a composite was studied using SEM. Class V cavities prepared in extracted teeth were restored with two commercial glass ionomers and a composite. Teeth were randomly divided into groups and each group treated for 24 h with one of the following fluoride gels: acidulated phosphate fluoride (pH5), stannous fluoride (pH4.5), sodium fluoride (pH7), and a non-proprietary sodium fluoride (pH5.8). Surface degradation of the restorations was studied using SEM, rated according to specific criteria, and statistically analyzed by the Wilcoxon test (Rank Sums). It was found that the APF and the non-proprietary gel had a significant effect on both Gl matrix and particles and on the composite particles (p < 0.01). The neutral sodium fluoride had no significant effect on the materials (p > 0.01).